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Baedorf-Kassis E, Murn M, Dzierba AL, Serra AL, Garcia I, Minus E, Padilla C, Sarge T, Goodspeed VM, Matthay MA, Gong MN, Cook D, Loring SH, Talmor D, Beitler JR. Respiratory drive heterogeneity associated with systemic inflammation and vascular permeability in acute respiratory distress syndrome. Crit Care 2024; 28:136. [PMID: 38654391 PMCID: PMC11036740 DOI: 10.1186/s13054-024-04920-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 04/17/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND In acute respiratory distress syndrome (ARDS), respiratory drive often differs among patients with similar clinical characteristics. Readily observable factors like acid-base state, oxygenation, mechanics, and sedation depth do not fully explain drive heterogeneity. This study evaluated the relationship of systemic inflammation and vascular permeability markers with respiratory drive and clinical outcomes in ARDS. METHODS ARDS patients enrolled in the multicenter EPVent-2 trial with requisite data and plasma biomarkers were included. Neuromuscular blockade recipients were excluded. Respiratory drive was measured as PES0.1, the change in esophageal pressure during the first 0.1 s of inspiratory effort. Plasma angiopoietin-2, interleukin-6, and interleukin-8 were measured concomitantly, and 60-day clinical outcomes evaluated. RESULTS 54.8% of 124 included patients had detectable respiratory drive (PES0.1 range of 0-5.1 cm H2O). Angiopoietin-2 and interleukin-8, but not interleukin-6, were associated with respiratory drive independently of acid-base, oxygenation, respiratory mechanics, and sedation depth. Sedation depth was not significantly associated with PES0.1 in an unadjusted model, or after adjusting for mechanics and chemoreceptor input. However, upon adding angiopoietin-2, interleukin-6, or interleukin-8 to models, lighter sedation was significantly associated with higher PES0.1. Risk of death was less with moderate drive (PES0.1 of 0.5-2.9 cm H2O) compared to either lower drive (hazard ratio 1.58, 95% CI 0.82-3.05) or higher drive (2.63, 95% CI 1.21-5.70) (p = 0.049). CONCLUSIONS Among patients with ARDS, systemic inflammatory and vascular permeability markers were independently associated with higher respiratory drive. The heterogeneous response of respiratory drive to varying sedation depth may be explained in part by differences in inflammation and vascular permeability.
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Affiliation(s)
- Elias Baedorf-Kassis
- Division of Pulmonary and Critical Care Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael Murn
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Amy L Dzierba
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
- Department of Pharmacy, New York-Presbyterian Hospital, New York, NY, USA
| | - Alexis L Serra
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Ivan Garcia
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Emily Minus
- Departments of Medicine and Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Clarissa Padilla
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Todd Sarge
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Valerie M Goodspeed
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael A Matthay
- Departments of Medicine and Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Michelle N Gong
- Department of Critical Care Medicine, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, USA
| | - Deborah Cook
- St. Joseph's Hospital and McMaster University, Hamilton, ON, Canada
| | - Stephen H Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Daniel Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jeremy R Beitler
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA.
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA.
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Butler JP, Banzett RB, Loring SH. Julius Comroe Is Right: Positive and Negative Pressure Ventilation Are The Same. Am J Respir Crit Care Med 2023. [PMID: 37311258 PMCID: PMC10395495 DOI: 10.1164/rccm.202303-0617le] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 05/31/2023] [Indexed: 06/15/2023] Open
Affiliation(s)
- James P Butler
- Harvard School of Public Health, Environmental Health, Boston, Massachusetts, United States;
| | - Robert B Banzett
- Harvard Med Sch/Beth Israel Deaconess MC, Div Pulmonary, Critical Care & Sleep, Boston, Massachusetts, United States
| | - Stephen H Loring
- Beth Israel Deaconess Medical Center, Anesthesia, Boston, Massachusetts, United States
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3
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Sarge T, Baedorf-Kassis E, Banner-Goodspeed V, Novack V, Loring SH, Gong MN, Cook D, Talmor D, Beitler JR. Effect of Esophageal Pressure-Guided Positive End-Expiratory Pressure on Survival from Acute Respiratory Distress Syndrome: A Risk-Based and Mechanistic Reanalysis of the EPVent-2 Trial. Am J Respir Crit Care Med 2021; 204:1153-1163. [PMID: 34464237 DOI: 10.1164/rccm.202009-3539oc] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE In acute respiratory distress syndrome (ARDS), the effect of positive end-expiratory pressure (PEEP) may depend on the extent to which multiorgan dysfunction contributes to risk of death, and the precision with which PEEP is titrated to attenuate atelectrauma without exacerbating overdistension. OBJECTIVE To evaluate whether multiorgan dysfunction and lung mechanics modified treatment effect in EPVent-2, a multicenter trial of esophageal pressure (PES)-guided PEEP versus empirical high PEEP in moderate-to-severe ARDS. METHODS This post-hoc reanalysis of EPVent-2 evaluated for heterogeneity of treatment effect on mortality by baseline multiorgan dysfunction, determined via Acute Physiology and Chronic Health Evaluation-II (APACHE-II). It also evaluated whether PEEP titrated to end-expiratory transpulmonary pressure near 0 cmH2O was associated with survival. MEASUREMENTS AND MAIN RESULTS All 200 trial participants were included. Treatment effect on 60-day mortality differed by multiorgan dysfunction severity (p=0.03 for interaction). PES-guided PEEP was associated with lower mortality among patients with lower APACHE-II (HR 0.43, 95% CI 0.20-0.92 for APACHE-II less than median) and may have had the opposite effect in patients with higher APACHE-II (HR 1.69; 95% CI 0.93-3.05). Independent of treatment group or multiorgan dysfunction severity, mortality was lowest when PEEP titration achieved end-expiratory transpulmonary pressure near 0 cmH2O. CONCLUSIONS The effect on survival of PES-guided PEEP, compared to empirical high PEEP, differed by multiorgan dysfunction severity. Independent of multiorgan dysfunction, PEEP titrated to end-expiratory transpulmonary pressure closer to 0 cmH2O was associated with greater survival than more positive or negative values. These findings warrant prospective testing in a future trial.
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Affiliation(s)
- Todd Sarge
- Beth Israel Deaconess Medical Center, 1859, Anesthesia, Critical Care, and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Elias Baedorf-Kassis
- Beth Israel Deaconess Medical Center, 1859, Pulmonary and Critical Care Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Valerie Banner-Goodspeed
- Beth Israel Deaconess Medical Center, 1859, Anesthesia, Critical Care, and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Victor Novack
- Soroka Medical Center, 26746, Clinical Research Center, Beer-Sheva, Israel
| | - Stephen H Loring
- Beth Israel Deaconess Medical Center, 1859, Anesthesia, Critical Care, and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Michelle N Gong
- Montefiore Medical Center, 2013, Division of Critical Care Medicine, Bronx, New York, United States.,Albert Einstein College of Medicine, 2006, Bronx, New York, United States
| | - Deborah Cook
- McMaster University, 3710, Department of Medicine, Pathology & Molecular Medicine, Hamilton, Ontario, Canada
| | - Daniel Talmor
- Beth Israel Deaconess Medical Center, 1859, Anesthesia, Critical Care, and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Jeremy R Beitler
- Columbia University College of Physicians and Surgeons, 12294, Center for Acute Respiratory Failure and Division of Pulmonary, Allergy, and Critical Care Medicine, New York, New York, United States.,NewYork-Presbyterian Hospital, 25065, New York, New York, United States;
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4
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Baedorf Kassis E, Su HK, Graham AR, Novack V, Loring SH, Talmor DS. Reverse Trigger Phenotypes in Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2021; 203:67-77. [PMID: 32809842 DOI: 10.1164/rccm.201907-1427oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Rationale: Reverse triggering is an underexplored form of dyssynchrony with important clinical implications in patients with acute respiratory distress syndrome.Objectives: This retrospective study identified reverse trigger phenotypes and characterized their impacts on Vt and transpulmonary pressure.Methods: Fifty-five patients with acute respiratory distress syndrome on pressure-regulated ventilator modes were included. Four phenotypes of reverse triggering with and without breath stacking and their impact on lung inflation and deflation were investigated.Measurements and Main Results: Inflation volumes, respiratory muscle pressure generation, and transpulmonary pressures were determined and phenotypes differentiated using Campbell diagrams of respiratory activity. Reverse triggering was detected in 25 patients, 15 with associated breath stacking, and 13 with stable reverse triggering consistent with respiratory entrainment. Phenotypes were associated with variable levels of inspiratory effort (mean 4-10 cm H2O per phenotype). Early reverse triggering with early expiratory relaxation increased Vts (88 [64-113] ml) and inspiratory transpulmonary pressures (3 [2-3] cm H2O) compared with passive breaths. Early reverse triggering with delayed expiratory relaxation increased Vts (128 [86-170] ml) and increased inspiratory and mean-expiratory transpulmonary pressure (7 [5-9] cm H2O and 5 [4-6] cm H2O). Mid-cycle reverse triggering (initiation during inflation and maximal effort during deflation) increased Vt (51 [38-64] ml), increased inspiratory and mean-expiratory transpulmonary pressure (3 [2-4] cm H2O and 3 [2-3] cm H2O), and caused incomplete exhalation. Late reverse triggering (occurring exclusively during exhalation) increased mean expiratory transpulmonary pressure (2 [1-2] cm H2O) and caused incomplete exhalation. Breath stacking resulted in large delivered volumes (176 [155-197] ml).Conclusions: Reverse triggering causes variable physiological effects, depending on the phenotype. Differentiation of phenotype effects may be important to understand the clinical impacts of these events.
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Affiliation(s)
- Elias Baedorf Kassis
- Division of Pulmonary and Critical Care.,Harvard Medical School, Boston, Massachusetts; and
| | - Henry K Su
- Department of Anesthesia, Critical Care and Pain Medicine, and.,Harvard Medical School, Boston, Massachusetts; and
| | - Alexander R Graham
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts; and
| | - Victor Novack
- Clinical Research Center, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, and.,Harvard Medical School, Boston, Massachusetts; and
| | - Daniel S Talmor
- Department of Anesthesia, Critical Care and Pain Medicine, and.,Harvard Medical School, Boston, Massachusetts; and
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5
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Schaefer MS, Loring SH, Talmor D, Baedorf-Kassis EN. Comparison of mechanical power estimations in mechanically ventilated patients with ARDS: a secondary data analysis from the EPVent study. Intensive Care Med 2020; 47:130-132. [PMID: 33078240 DOI: 10.1007/s00134-020-06282-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2020] [Indexed: 12/16/2022]
Affiliation(s)
- Maximilian S Schaefer
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA. .,Department of Anaesthesiology, Duesseldorf University Hospital, Duesseldorf, Germany.
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA
| | - Daniel Talmor
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA
| | - Elias N Baedorf-Kassis
- Department of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA
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6
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Sands SA, Terrill PI, Edwards BA, Taranto Montemurro L, Azarbarzin A, Marques M, de Melo CM, Loring SH, Butler JP, White DP, Wellman A. Quantifying the Arousal Threshold Using Polysomnography in Obstructive Sleep Apnea. Sleep 2019; 41:4608578. [PMID: 29228393 DOI: 10.1093/sleep/zsx183] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 11/07/2017] [Indexed: 11/14/2022] Open
Abstract
Study Objectives Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Methods Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al.) to the pattern of ventilation during spontaneous respiratory events. Conceptually, the magnitude of the airflow signal immediately after arousal onset reveals information on the underlying ventilatory drive that triggered the arousal. Polysomnographic arousal threshold measures were compared with gold standard values taken from esophageal pressure and intraoesophageal diaphragm electromyography recorded simultaneously (N = 29). Comparisons were also made to arousal threshold measures using continuous positive airway pressure (CPAP) dial-downs (N = 28). The validity of using (linearized) nasal pressure rather than pneumotachograph ventilation was also assessed (N = 11). Results Polysomnographic arousal threshold values were correlated with those measured using esophageal pressure and diaphragm EMG (R = 0.79, p < .0001; R = 0.73, p = .0001), as well as CPAP manipulation (R = 0.73, p < .0001). Arousal threshold estimates were similar using nasal pressure and pneumotachograph ventilation (R = 0.96, p < .0001). Conclusions The arousal threshold in patients with OSA can be estimated using polysomnographic signals and may enable more personalized therapeutic interventions for patients with a low arousal threshold.
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Affiliation(s)
- Scott A Sands
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.,Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Victoria, Australia
| | - Philip I Terrill
- School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland, Australia
| | - Bradley A Edwards
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.,Department of Physiology, Sleep and Circadian Medicine Laboratory, Monash University, Melbourne, Victoria, Australia.,School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia
| | - Luigi Taranto Montemurro
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Ali Azarbarzin
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Melania Marques
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.,Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil
| | - Camila M de Melo
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - James P Butler
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - David P White
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
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7
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Beitler JR, Sarge T, Banner-Goodspeed VM, Gong MN, Cook D, Novack V, Loring SH, Talmor D. Effect of Titrating Positive End-Expiratory Pressure (PEEP) With an Esophageal Pressure-Guided Strategy vs an Empirical High PEEP-Fio2 Strategy on Death and Days Free From Mechanical Ventilation Among Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial. JAMA 2019; 321:846-857. [PMID: 30776290 PMCID: PMC6439595 DOI: 10.1001/jama.2019.0555] [Citation(s) in RCA: 222] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
IMPORTANCE Adjusting positive end-expiratory pressure (PEEP) to offset pleural pressure might attenuate lung injury and improve patient outcomes in acute respiratory distress syndrome (ARDS). OBJECTIVE To determine whether PEEP titration guided by esophageal pressure (PES), an estimate of pleural pressure, was more effective than empirical high PEEP-fraction of inspired oxygen (Fio2) in moderate to severe ARDS. DESIGN, SETTING, AND PARTICIPANTS Phase 2 randomized clinical trial conducted at 14 hospitals in North America. Two hundred mechanically ventilated patients aged 16 years and older with moderate to severe ARDS (Pao2:Fio2 ≤200 mm Hg) were enrolled between October 31, 2012, and September 14, 2017; long-term follow-up was completed July 30, 2018. INTERVENTIONS Participants were randomized to PES-guided PEEP (n = 102) or empirical high PEEP-Fio2 (n = 98). All participants received low tidal volumes. MAIN OUTCOMES AND MEASURES The primary outcome was a ranked composite score incorporating death and days free from mechanical ventilation among survivors through day 28. Prespecified secondary outcomes included 28-day mortality, days free from mechanical ventilation among survivors, and need for rescue therapy. RESULTS Two hundred patients were enrolled (mean [SD] age, 56 [16] years; 46% female) and completed 28-day follow-up. The primary composite end point was not significantly different between treatment groups (probability of more favorable outcome with PES-guided PEEP: 49.6% [95% CI, 41.7% to 57.5%]; P = .92). At 28 days, 33 of 102 patients (32.4%) assigned to PES-guided PEEP and 30 of 98 patients (30.6%) assigned to empirical PEEP-Fio2 died (risk difference, 1.7% [95% CI, -11.1% to 14.6%]; P = .88). Days free from mechanical ventilation among survivors was not significantly different (median [interquartile range]: 22 [15-24] vs 21 [16.5-24] days; median difference, 0 [95% CI, -1 to 2] days; P = .85). Patients assigned to PES-guided PEEP were significantly less likely to receive rescue therapy (4/102 [3.9%] vs 12/98 [12.2%]; risk difference, -8.3% [95% CI, -15.8% to -0.8%]; P = .04). None of the 7 other prespecified secondary clinical end points were significantly different. Adverse events included gross barotrauma, which occurred in 6 patients with PES-guided PEEP and 5 patients with empirical PEEP-Fio2. CONCLUSIONS AND RELEVANCE Among patients with moderate to severe ARDS, PES-guided PEEP, compared with empirical high PEEP-Fio2, resulted in no significant difference in death and days free from mechanical ventilation. These findings do not support PES-guided PEEP titration in ARDS. TRIAL REGISTRATION ClinicalTrials.gov Identifier NCT01681225.
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Affiliation(s)
- Jeremy R. Beitler
- Center for Acute Respiratory Failure and Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians & Surgeons, New York, New York
| | - Todd Sarge
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Valerie M. Banner-Goodspeed
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Michelle N. Gong
- Division of Critical Care Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York
| | - Deborah Cook
- Department of Medicine, St Joseph’s Hospital and McMaster University, Hamilton, Ontario, Canada
| | - Victor Novack
- Soroka Clinical Research Center, Soroka University Medical Center, Beer-Sheva, Israel
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Daniel Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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8
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Abstract
Patients on high inspired O2 concentrations are at risk of atelectasis, a problem that has been quantitatively assessed using analysis of ratio of ventilation to perfusion (V̇a/Q̇) equations. This approach ignores the potential of the elastic properties of the lung to support gas exchange through "apneic" oxygenation in units with no tidal ventilation, and is based on an error in the conservation of mass equations. To fill this gap, we correct the error and compare the pressure drops associated with apneic gas exchange with the pressure differences that can be supported by lung recoil. We analyze a worst case scenario: a small test unit in the Weibel model A tree structure with zero tidal ventilation, 100% inspired O2, the rest of the lung being normally ventilated tidally. We first computed the gas flux to the (unventilated) test unit and estimated the associated pressure drops. We then computed the difference in local gas pressure relative to the surrounding lung that would cause the unit to collapse. We compared these two, and finally computed the degree of airway narrowing that would effect change from the stable (apneic gas exchange) regime to the unstable regime leading to collapse. We find that except under extreme conditions of loss of airway caliber exceeding roughly 90%, lung recoil is sufficient to maintain oxygenation through convective transport alone. We further argue that the fundamental V̇a/Q̇ equations are invalid in these circumstances, and that the issue of atelectasis in low V̇a/Q̇ will require modifications to account for this additional mode of gas exchange. NEW & NOTEWORTHY Breathing high concentrations of oxygen increases the likelihood of atelectasis because of oxygen absorption, which is thought to be inevitable in regions with relatively low ventilation/perfusion ratios. However, airspaces of the lung resist collapse because of the forces of interdependence, and can, with low or even zero active tidal ventilation, draw in an inspiratory flow of oxygen sufficient to replace the oxygen consumed, thus preventing collapse of airspaces served by all but the most narrowed airways.
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Affiliation(s)
- James P Butler
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts.,Department of Medicine, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts.,Department of Environmental Health, Harvard TH Chan School of Public Health , Boston, Massachusetts
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California San Diego , La Jolla, California
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School , Boston, Massachusetts
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9
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Abstract
Ventilator management of patients with acute respiratory distress syndrome (ARDS) has been characterized by implementation of basic physiology principles by minimizing harmful distending pressures and preventing lung derecruitment. Such strategies have led to significant improvements in outcomes. Positive end expiratory pressure (PEEP) is an important part of a lung protective strategy but there is no standardized method to set PEEP level. With widely varying types of lung injury, body habitus and pulmonary mechanics, the use of esophageal manometry has become important for personalization and optimization of mechanical ventilation in patients with ARDS. Esophageal manometry estimates pleural pressures, and can be used to differentiate the chest wall and lung (transpulmonary) contributions to the total respiratory system mechanics. Elevated pleural pressures may result in negative transpulmonary pressures at end expiration, leading to lung collapse. Measuring the esophageal pressures and adjusting PEEP to make transpulmonary pressures positive can decrease atelectasis, derecruitment of lung, and cyclical opening and closing of airways and alveoli, thus optimizing lung mechanics and oxygenation. Although there is some spatial and positional artifact, esophageal pressures in numerous animal and human studies in healthy, obese and critically ill patients appear to be a good estimate for the "effective" pleural pressure. Multiple studies have illustrated the benefit of using esophageal pressures to titrate PEEP in patients with obesity and with ARDS. Esophageal pressure monitoring provides a window into the unique physiology of a patient and helps improve clinical decision making at the bedside.
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Affiliation(s)
- Elias Baedorf Kassis
- Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Daniel Talmor
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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10
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Servais AB, Valenzuela CD, Ysasi AB, Wagner WL, Kienzle A, Loring SH, Tsuda A, Ackermann M, Mentzer SJ. Pressure-decay testing of pleural air leaks in intact murine lungs: evidence for peripheral airway regulation. Physiol Rep 2018; 6:e13712. [PMID: 29845759 PMCID: PMC5974726 DOI: 10.14814/phy2.13712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/23/2018] [Accepted: 04/25/2018] [Indexed: 11/24/2022] Open
Abstract
The critical care management of pleural air leaks can be challenging in all patients, but particularly in patients on mechanical ventilation. To investigate the effect of central airway pressure and pleural pressure on pulmonary air leaks, we studied orotracheally intubated mice with pleural injuries. We used clinically relevant variables - namely, airway pressure and pleural pressure - to investigate flow through peripheral air leaks. The model studied the pleural injuries using a pressure-decay maneuver. The pressure-decay maneuver involved a 3 sec ramp to 30 cmH2 0 followed by a 3 sec breath hold. After pleural injury, the pressure-decay maneuver demonstrated a distinctive airway pressure time history. Peak inflation was followed by a rapid decrease to a lower plateau phase. The decay phase of the inflation maneuver was influenced by the injury area. The rate of pressure decline with multiple injuries (28 ± 8 cmH2 0/sec) was significantly greater than a single injury (12 ± 3 cmH2 O/sec) (P < 0.05). In contrast, the plateau phase pressure was independent of injury surface area, but dependent upon transpulmonary pressure. The mean plateau transpulmonary pressure was 18 ± 0.7 cm H2 O. Finally, analysis of the inflation ramp demonstrated that nearly all volume loss occurred at the end of inflation (P < 0.001). We conclude that the air flow through peripheral lung injuries was greatest at increased lung volumes and limited by peripheral airway closure. In addition to suggesting an intrinsic mechanism for limiting flow through peripheral air leaks, these findings suggest the utility of positive end-expiratory pressure and negative pleural pressure to maintain lung volumes in patients with pleural injuries.
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Affiliation(s)
- Andrew B. Servais
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
| | - Cristian D. Valenzuela
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
| | - Alexandra B. Ysasi
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
| | - Willi L. Wagner
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
- Institute of Functional and Clinical AnatomyUniversity Medical Center of the Johannes Gutenberg‐UniversityMainzGermany
| | - Arne Kienzle
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care, and Pain MedicineBeth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMassachusetts
| | - Akira Tsuda
- Molecular and Integrative Physiological SciencesHarvard School of Public HealthBostonMassachusetts
| | - Maximilian Ackermann
- Institute of Functional and Clinical AnatomyUniversity Medical Center of the Johannes Gutenberg‐UniversityMainzGermany
| | - Steven J. Mentzer
- Laboratory of Adaptive and Regenerative BiologyBrigham & Women's HospitalHarvard Medical SchoolBostonMassachusetts
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Baedorf Kassis E, Loring SH, Talmor D. Lung volumes and transpulmonary pressure are decreased with expiratory effort and restored with passive breathing in ARDS: a reapplication of the traditional Campbell diagram. Intensive Care Med 2018. [PMID: 29516120 DOI: 10.1007/s00134-018-5105-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Elias Baedorf Kassis
- Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Bulfinch 108, Boston, MA, 02114, USA.
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA
| | - Daniel Talmor
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA
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Mentzer SJ, Tsuda A, Loring SH. Pleural mechanics and the pathophysiology of air leaks. J Thorac Cardiovasc Surg 2017; 155:2182-2189. [PMID: 29397977 DOI: 10.1016/j.jtcvs.2017.12.062] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 12/10/2017] [Accepted: 12/15/2017] [Indexed: 11/16/2022]
Affiliation(s)
- Steven J Mentzer
- Division of Thoracic Surgery, Brigham & Women's Hospital, Harvard Medical School, Boston, Mass.
| | - Akira Tsuda
- Molecular and Integrative Physiological Sciences, Harvard School of Public Health, Boston, Mass
| | - Stephen H Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass
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Affiliation(s)
- Stephen H Loring
- 1 Department of Anesthesia, Critical Care, and Pain Medicine Beth Israel Deaconess Medical Center and Harvard Medical School Boston, Massachusetts
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de Melo CM, Taranto-Montemurro L, Butler JP, White DP, Loring SH, Azarbarzin A, Marques M, Berger PJ, Wellman A, Sands SA. Stable Breathing in Patients With Obstructive Sleep Apnea Is Associated With Increased Effort but Not Lowered Metabolic Rate. Sleep 2017; 40:4004820. [PMID: 28977669 PMCID: PMC5805127 DOI: 10.1093/sleep/zsx128] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Study objectives In principle, if metabolic rate were to fall during sleep in a patient with obstructive sleep apnea (OSA), ventilatory requirements could be met without increased respiratory effort thereby favoring stable breathing. Indeed, most patients achieve periods of stable flow-limited breathing without respiratory events for periods during the night for reasons that are unclear. Thus, we tested the hypothesis that in patients with OSA, periods of stable breathing occur when metabolic rate (VO2) declines. Methods Twelve OSA patients (apnea-hypopnea index >15 events/h) completed overnight polysomnography including measurements of VO2 (using ventilation and intranasal PO2) and respiratory effort (esophageal pressure). Results Contrary to our hypothesis, VO2 did not differ between stable and unstable breathing periods in non-REM stage 2 (208 ± 20 vs. 213 ± 18 mL/min), despite elevated respiratory effort during stable breathing (26 ± 2 versus 23 ± 2 cmH2O, p = .03). However, VO2 was lowered during deeper sleep (244 to 179 mL/min from non-REM stages 1 to 3, p = .04) in conjunction with more stable breathing. Further analysis revealed that airflow obstruction curtailed metabolism in both stable and unstable periods, since CPAP increased VO2 by 14% in both cases (p = .02, .03, respectively). Patients whose VO2 fell most during sleep avoided an increase in PCO2 and respiratory effort. Conclusions OSA patients typically convert from unstable to stable breathing without lowering metabolic rate. During sleep, OSA patients labor with increased respiratory effort but fail to satisfy metabolic demand even in the absence of overt respiratory events.
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Affiliation(s)
- Camila M de Melo
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
- Department of Psychobiology, Universidade Federal de Sao Paulo UNIFESP, Sao Paulo, SP, Brazil
| | - Luigi Taranto-Montemurro
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - James P Butler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - David P White
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Ali Azarbarzin
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Melania Marques
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
- Sleep Laboratory, Pulmonary Division, Heart Institute (Incor), Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Philip J Berger
- The Ritchie Centre, Hudson Institute of Medical Research, Monash University, Melbourne, VIC, Australia
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
- Department of Allergy Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, VIC, Australia
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Loring SH, Topulos GP, Hubmayr RD. Transpulmonary Pressure: The Importance of Precise Definitions and Limiting Assumptions. Am J Respir Crit Care Med 2017; 194:1452-1457. [PMID: 27606837 DOI: 10.1164/rccm.201512-2448cp] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Recent studies applying the principles of respiratory mechanics to respiratory disease have used inconsistent and mutually exclusive definitions of the term "transpulmonary pressure." By the traditional definition, transpulmonary pressure is the pressure across the whole lung, including the intrapulmonary airways, (i.e., the pressure difference between the opening to the pulmonary airway and the pleural surface). However, more recently transpulmonary pressure has also been defined as the pressure across only the lung tissue (i.e., the pressure difference between the alveolar space and the pleural surface), traditionally known as the "elastic recoil pressure of the lung." Multiple definitions of the same term, and failure to recognize their underlying assumptions, have led to different interpretations of lung physiology and conclusions about appropriate therapy for patients. It is our view that many current controversies in the physiological interpretation of disease are caused by the lack of consistency in the definitions of these common physiological terms. In this article, we discuss the historical uses of these terms and recent misconceptions that may have resulted when these terms were confused. These misconceptions include assertions that normal pleural pressure must be negative (subatmospheric) and that a pressure in the pleural space may not be substantially positive when a subject is relaxed with an open airway. We urge specificity and uniformity when using physiological terms to define the physical state of the lungs, the chest wall, and the integrated respiratory system.
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Affiliation(s)
- Stephen H Loring
- 1 Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - George P Topulos
- 2 Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; and
| | - Rolf D Hubmayr
- 3 Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota
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Genta PR, Sands SA, Butler JP, Loring SH, Katz ES, Demko BG, Kezirian EJ, White DP, Wellman A. Airflow Shape Is Associated With the Pharyngeal Structure Causing OSA. Chest 2017; 152:537-546. [PMID: 28651794 DOI: 10.1016/j.chest.2017.06.017] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/03/2017] [Accepted: 06/01/2017] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND OSA results from the collapse of different pharyngeal structures (soft palate, tongue, lateral walls, and epiglottis). The structure involved in collapse has been shown to impact non-CPAP OSA treatment. Different inspiratory airflow shapes are also observed among patients with OSA. We hypothesized that inspiratory flow shape reflects the underlying pharyngeal structure involved in airway collapse. METHODS Subjects with OSA were studied with a pediatric endoscope and simultaneous nasal flow and pharyngeal pressure recordings during natural sleep. The mechanism causing collapse was classified as tongue-related, isolated palatal, lateral walls, or epiglottis. Flow shape was classified according to the degree of negative effort dependence (NED), defined as the percent reduction in inspiratory flow from peak to plateau. RESULTS Thirty-one subjects with OSA (mean apnea-hypopnea index score ± SD, 54 ± 27 events/h) who were 50 ± 9 years of age were studied. NED was associated with the structure causing collapse (P < .001). Tongue-related obstruction (n = 13) was associated with a small amount of NED (median, 19; interquartile range [IQR], 14%-25%). Moderate NED was found among subjects with isolated palatal collapse (median, 45; IQR, 39%-52%; n = 8) and lateral wall collapse (median, 50; IQR, 44%-64%; n = 8). The epiglottis was associated with severe NED (median, 89; IQR, 78%-91%) and abrupt discontinuities in inspiratory flow (n = 9). CONCLUSIONS Inspiratory flow shape is influenced by the pharyngeal structure causing collapse. Flow shape analysis may be used as a noninvasive tool to help determine the pharyngeal structure causing collapse.
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Affiliation(s)
- Pedro R Genta
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil.
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, VIC, Australia
| | - James P Butler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Eliot S Katz
- Division of Respiratory Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | | | - Eric J Kezirian
- USC Caruso Department of Otolaryngology - Head & Neck Surgery, Keck School of Medicine of USC, Los Angeles, CA
| | - David P White
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
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Affiliation(s)
- Stephen H. Loring
- Beth Israel Deaconess Medical CenterBoston, Massachusetts
- Harvard Medical SchoolBoston, Massachusetts
| | - George P. Topulos
- Brigham and Women’s HospitalBoston, Massachusetts
- Harvard Medical SchoolBoston, Massachusetts
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18
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Baedorf Kassis E, Loring SH, Talmor D. Recruitment maneuvers: using transpulmonary pressure to help Goldilocks. Intensive Care Med 2017; 43:1162-1163. [PMID: 28386726 DOI: 10.1007/s00134-017-4784-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2017] [Indexed: 11/29/2022]
Affiliation(s)
- E Baedorf Kassis
- Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Bulfinch 108, Boston, MA, 02114, USA.
| | - S H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA
| | - D Talmor
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA
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19
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Genta PR, Edwards BA, Sands SA, Owens RL, Butler JP, Loring SH, White DP, Wellman A. Tube Law of the Pharyngeal Airway in Sleeping Patients with Obstructive Sleep Apnea. Sleep 2016; 39:337-43. [PMID: 26446124 DOI: 10.5665/sleep.5440] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 09/05/2015] [Indexed: 12/22/2022] Open
Abstract
STUDY OBJECTIVES Obstructive sleep apnea (OSA) is characterized by repetitive pharyngeal collapse during sleep. However, the dynamics of pharyngeal narrowing and re-expansion during flow-limited breathing are not well described. The static pharyngeal tube law (end-expiratory area versus luminal pressure) has demonstrated increasing pharyngeal compliance as luminal pressure decreases, indicating that the airway would be sucked closed with sufficient inspiratory effort. On the contrary, the airway is rarely sucked closed during inspiratory flow limitation, suggesting that the airway is getting stiffer. Therefore, we hypothesized that during inspiratory flow limitation, as opposed to static conditions, the pharynx becomes stiffer as luminal pressure decreases. METHODS Upper airway endoscopy and simultaneous measurements of airflow and epiglottic pressure were performed during natural nonrapid eye movement sleep. Continuous positive (or negative) airway pressure was used to induce flow limitation. Flow-limited breaths were selected for airway cross-sectional area measurements. Relative airway area was quantified as a percentage of end-expiratory area. Inspiratory airway radial compliance was calculated at each quintile of epiglottic pressure versus airway area plot (tube law). RESULTS Eighteen subjects (14 males) with OSA (apnea-hypopnea index = 57 ± 27 events/h), aged 49 ± 8 y, with a body mass index of 35 ± 6 kg/m(2) were studied. A total of 163 flow limited breaths were analyzed (9 ± 3 breaths per subject). Compliances at the fourth (2.0 ± 4.7 % area/cmH2O) and fifth (0.0 ± 1.7 % area/cmH2O) quintiles were significantly lower than the first (12.2 ± 5.5 % area/cmH2O) pressure quintile (P < 0.05). CONCLUSIONS The pharyngeal tube law is concave (airway gets stiffer as luminal pressure decreases) during respiratory cycles under inspiratory flow limitation.
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Affiliation(s)
- Pedro R Genta
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA.,Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas, University of São Paulo School of Medicine, São Paulo, Brazil
| | - Bradley A Edwards
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA.,Department of Allergy Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Australia
| | - Robert L Owens
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | - James P Butler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - David P White
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
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Abstract
ABSTRACT
We measured esophageal pressures, respiratory flow rates, and expired O2 and CO2 in six adult bottlenose dolphins (Tursiops truncatus) during voluntary breaths and maximal (chuff) respiratory efforts. The data were used to estimate the dynamic specific lung compliance (sCL), the O2 consumption rate (V̇O2) and CO2 production rates (V̇CO2) during rest. Our results indicate that bottlenose dolphins have the capacity to generate respiratory flow rates that exceed 130 l s−1 and 30 l s−1 during expiration and inspiration, respectively. The esophageal pressures indicated that expiration is passive during voluntary breaths, but active during maximal efforts, whereas inspiration is active for all breaths. The average sCL of dolphins was 0.31±0.04 cmH2O−1, which is considerably higher than that of humans (0.08 cmH2O−1) and that previously measured in a pilot whale (0.13 cmH2O−1). The average estimated V̇O2 and V̇CO2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O2 min−1 and 0.589 to 0.851 l CO2 min−1, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. In addition, our custom-made system allows us to approximate end tidal gas composition. Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.
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Affiliation(s)
- Andreas Fahlman
- Department of Life Science, Texas A&M University-Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Gregg Levine
- Dolphin Quest, Oahu, 5000 Kahala Ave, Honolulu, HI 96816, USA
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Owens RL, Edwards BA, Eckert DJ, Jordan AS, Sands SA, Malhotra A, White DP, Loring SH, Butler JP, Wellman A. An Integrative Model of Physiological Traits Can be Used to Predict Obstructive Sleep Apnea and Response to Non Positive Airway Pressure Therapy. Sleep 2015; 38:961-70. [PMID: 25515107 DOI: 10.5665/sleep.4750] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/07/2014] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Both anatomical and nonanatomical traits are important in obstructive sleep apnea (OSA) pathogenesis. We have previously described a model combining these traits, but have not determined its diagnostic accuracy to predict OSA. A valid model, and knowledge of the published effect sizes of trait manipulation, would also allow us to predict the number of patients with OSA who might be effectively treated without using positive airway pressure (PAP). DESIGN, PARTICIPANTS AND INTERVENTION Fifty-seven subjects with and without OSA underwent standard clinical and research sleep studies to measure OSA severity and the physiological traits important for OSA pathogenesis, respectively. The traits were incorporated into a physiological model to predict OSA. The model validity was determined by comparing the model prediction of OSA to the clinical diagnosis of OSA. The effect of various trait manipulations was then simulated to predict the proportion of patients treated by each intervention. MEASUREMENTS AND RESULTS The model had good sensitivity (80%) and specificity (100%) for predicting OSA. A single intervention on one trait would be predicted to treat OSA in approximately one quarter of all patients. Combination therapy with two interventions was predicted to treat OSA in ∼50% of patients. CONCLUSIONS An integrative model of physiological traits can be used to predict population-wide and individual responses to non-PAP therapy. Many patients with OSA would be expected to be treated based on known trait manipulations, making a strong case for the importance of non-anatomical traits in OSA pathogenesis and the effectiveness of non-PAP therapies.
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Affiliation(s)
- Robert L Owens
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
| | - Bradley A Edwards
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
| | - Danny J Eckert
- Neuroscience Research Australia (NeuRA) and the School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Amy S Jordan
- Melbourne School of Physiological Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Scott A Sands
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
| | - Atul Malhotra
- Pulmonary and Critical Care Division, University of California - San Diego, La Jolla, CA
| | - David P White
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - James P Butler
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
| | - Andrew Wellman
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's and Harvard Medical School, Boston, MA
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Affiliation(s)
- Stephen H Loring
- From the Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, and Harvard Medical School - both in Boston (S.H.L.); and the Division of Pulmonary Critical Care and Sleep Medicine, University of California, San Diego, La Jolla (A.M.)
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Sands SA, Eckert DJ, Jordan AS, Edwards BA, Owens RL, Butler JP, Schwab RJ, Loring SH, Malhotra A, White DP, Wellman A. Enhanced upper-airway muscle responsiveness is a distinct feature of overweight/obese individuals without sleep apnea. Am J Respir Crit Care Med 2014; 190:930-7. [PMID: 25191791 DOI: 10.1164/rccm.201404-0783oc] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Body habitus is a major determinant of obstructive sleep apnea (OSA). However, many individuals do not have OSA despite being overweight/obese (body mass index > 25 kg/m(2)) for reasons that are not fully elucidated. OBJECTIVES To determine the key physiologic traits (upper-airway anatomy/collapsibility, upper-airway muscle responsiveness, chemoreflex control of ventilation, arousability from sleep) responsible for the absence of OSA in overweight/obese individuals. METHODS We compared key physiologic traits in 18 overweight/obese subjects without apnea (apnea-hypopnea index < 15 events per hour) with 25 overweight/obese matched patients with OSA (apnea-hypopnea index ≥ 15 events per hour) and 11 normal-weight nonapneic control subjects. Traits were measured by repeatedly lowering continuous positive airway pressure to subtherapeutic levels for 3 minutes during non-REM sleep. MEASUREMENTS AND MAIN RESULTS Overweight/obese subjects without apnea exhibited a less collapsible airway than overweight/obese patients with apnea (critical closing pressure: -3.7 ± 1.9 vs. 0.6 ± 1.2 cm H2O; P = 0.003; mean ± 95% confidence interval), but a more collapsible airway relative to normal-weight control subjects (-8.8 ± 3.1 cm H2O; P < 0.001). Notably, overweight/obese subjects without apnea exhibited a threefold greater upper-airway muscle responsiveness than both overweight/obese patients with apnea (Δgenioglossus EMG/Δepiglottic pressure: -0.49 [-0.22 to -0.79] vs. -0.15 [-0.09 to -0.22] %max/cm H2O; P = 0.008; mean [95% confidence interval]) and normal-weight control subjects (-0.16 [-0.04 to -0.30] %max/cm H2O; P = 0.02). Loop gain was elevated (more negative) in both overweight/obese groups and normal-weight control subjects (P = 0.02). Model-based analysis demonstrated that overweight/obese individuals without apnea rely on both more favorable anatomy and collapsibility and enhanced upper-airway dilator muscle responses to avoid OSA. CONCLUSIONS Overweight/obese individuals without apnea have a moderately compromised upper-airway structure that is mitigated by highly responsive upper-airway dilator muscles to avoid OSA. Elucidating the mechanisms underlying enhanced muscle responses in this population may provide clues for novel OSA interventions.
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Affiliation(s)
- Scott A Sands
- 1 Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
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Fahlman A, Loring SH, Johnson SP, Haulena M, Trites AW, Fravel VA, Van Bonn WG. Inflation and deflation pressure-volume loops in anesthetized pinnipeds confirms compliant chest and lungs. Front Physiol 2014; 5:433. [PMID: 25426080 PMCID: PMC4226140 DOI: 10.3389/fphys.2014.00433] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 10/22/2014] [Indexed: 11/13/2022] Open
Abstract
We examined structural properties of the marine mammal respiratory system, and tested Scholander's hypothesis that the chest is highly compliant by measuring the mechanical properties of the respiratory system in five species of pinniped under anesthesia (Pacific harbor seal, Phoca vitulina; northern elephant seal, Mirounga angustirostris; northern fur seal Callorhinus ursinus; California sea lion, Zalophus californianus; and Steller sea lion, Eumetopias jubatus). We found that the chest wall compliance (CCW) of all five species was greater than lung compliance (airways and alveoli, CL) as predicted by Scholander, which suggests that the chest provides little protection against alveolar collapse or lung squeeze. We also found that specific respiratory compliance was significantly greater in wild animals than in animals raised in an aquatic facility. While differences in ages between the two groups may affect this incidental finding, it is also possible that lung conditioning in free-living animals may increase pulmonary compliance and reduce the risk of lung squeeze during diving. Overall, our data indicate that compliance of excised pinniped lungs provide a good estimate of total respiratory compliance.
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Affiliation(s)
- Andreas Fahlman
- Life Sciences, Texas A&M University-Corpus Christi Corpus Christi, TX, USA
| | - Stephen H Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center Boston, MA, USA
| | | | | | - Andrew W Trites
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia Vancouver, BC, Canada
| | | | - William G Van Bonn
- The Marine Mammal Center Sausalito, CA, USA ; A. Watson Armour III Center for Animal Health and Welfare, Shedd Aquarium Chicago, IL, USA
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Wellman A, Genta PR, Owens RL, Edwards BA, Sands SA, Loring SH, White DP, Jackson AC, Pedersen OF, Butler JP. Test of the Starling resistor model in the human upper airway during sleep. J Appl Physiol (1985) 2014; 117:1478-85. [PMID: 25324514 DOI: 10.1152/japplphysiol.00259.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The human pharyngeal airway during sleep is conventionally modeled as a Starling resistor. However, inspiratory flow often decreases with increasing effort (negative effort dependence, NED) rather than remaining fixed as predicted by the Starling resistor model. In this study, we tested a major prediction of the Starling resistor model--that the resistance of the airway upstream from the site of collapse remains fixed during flow limitation. During flow limitation in 24 patients with sleep apnea, resistance at several points along the pharyngeal airway was measured using a pressure catheter with multiple sensors. Resistance between the nose and the site of collapse (the upstream segment) was measured before and after the onset of flow limitation to determine whether the upstream dimensions remained fixed (as predicted by the Starling resistor model) or narrowed (a violation of the Starling resistor model). The upstream resistance from early to mid inspiration increased considerably during flow limitation (by 35 ± 41 cmH2O · liter(-1) · s(-1), P < 0.001). However, there was a wide range of variability between patients, and the increase in upstream resistance was strongly correlated with the amount of NED (r = 0.75, P < 0.001). Therefore, patients with little NED exhibited little upstream narrowing (consistent with the Starling model), and patients with large NED exhibited large upstream narrowing (inconsistent with the Starling model). These findings support the idea that there is not a single model of pharyngeal collapse, but rather that different mechanisms may dominate in different patients. These differences could potentially be exploited for treatment selection.
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Affiliation(s)
- Andrew Wellman
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Pedro R Genta
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Robert L Owens
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Bradley A Edwards
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Scott A Sands
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Stephen H Loring
- Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - David P White
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Andrew C Jackson
- Department of Engineering, Boston University, Boston, Massachusetts; and
| | - Ole F Pedersen
- Institute of Public Health, University of Aarhus, Aarhus, Denmark
| | - James P Butler
- Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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Loring SH, Behazin N, Novero A, Novack V, Jones SB, O'Donnell CR, Talmor DS. Respiratory mechanical effects of surgical pneumoperitoneum in humans. J Appl Physiol (1985) 2014; 117:1074-9. [PMID: 25213641 DOI: 10.1152/japplphysiol.00552.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pneumoperitoneum for laparoscopic surgery is known to stiffen the chest wall and respiratory system, but its effects on resting pleural pressure in humans are unknown. We hypothesized that pneumoperitoneum would raise abdominal pressure, push the diaphragm into the thorax, raise pleural pressure, and squeeze the lung, which would become stiffer at low volumes as in severe obesity. Nineteen predominantly obese laparoscopic patients without pulmonary disease were studied supine (level), under neuromuscular blockade, before and after insufflation of CO2 to a gas pressure of 20 cmH2O. Esophageal pressure (Pes) and airway pressure (Pao) were measured to estimate pleural pressure and transpulmonary pressure (Pl = Pao - Pes). Changes in relaxation volume (Vrel, at Pao = 0) were estimated from changes in expiratory reserve volume, the volume extracted between Vrel, and the volume at Pao = -25 cmH2O. Inflation pressure-volume (Pao-Vl) curves from Vrel were assessed for evidence of lung compression due to high Pl. Respiratory mechanics were measured during ventilation with a positive end-expiratory pressure of 0 and 7 cmH2O. Pneumoperitoneum stiffened the chest wall and the respiratory system (increased elastance), but did not stiffen the lung, and positive end-expiratory pressure reduced Ecw during pneumoperitoneum. Contrary to our expectations, pneumoperitoneum at Vrel did not significantly change Pes [8.7 (3.4) to 7.6 (3.2) cmH2O; means (SD)] or expiratory reserve volume [183 (142) to 155 (114) ml]. The inflation Pao-Vl curve above Vrel did not show evidence of increased lung compression with pneumoperitoneum. These results in predominantly obese subjects can be explained by the inspiratory effects of abdominal pressure on the rib cage.
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Affiliation(s)
- Stephen H Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts;
| | - Negin Behazin
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Aileen Novero
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Victor Novack
- Soroka University Medical Center, Beer Sheva, Israel; and
| | - Stephanie B Jones
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Carl R O'Donnell
- Division of Pulmonary and Critical Care Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Daniel S Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
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Genta PR, Owens RL, Edwards BA, Sands SA, Eckert DJ, Butler JP, Loring SH, Malhotra A, Jackson AC, White DP, Wellman A. Influence of pharyngeal muscle activity on inspiratory negative effort dependence in the human upper airway. Respir Physiol Neurobiol 2014; 201:55-9. [PMID: 25020212 DOI: 10.1016/j.resp.2014.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/10/2014] [Accepted: 07/07/2014] [Indexed: 12/19/2022]
Abstract
The upper airway is often modeled as a Starling resistor, which predicts that flow is independent of inspiratory effort during flow limitation. However, while some obstructive sleep apnea (OSA) patients exhibit flat, Starling resistor-like flow limitation, others demonstrate considerable negative effort dependence (NED), defined as the percent reduction in flow from peak to mid-inspiration. We hypothesized that the variability in NED could be due to differences in phasic pharyngeal muscle activation between individuals. Therefore, we induced topical pharyngeal anesthesia to reduce phasic pharyngeal muscle activation to see if it increased NED. Twelve subjects aged 50±10 years with a BMI of 35±6 kg/m(2) and severe OSA (apnea-hypopnea index=52±28 events/h) were studied. NED and phasic genioglossus muscle activity (EMG(GG)) of flow limited breaths were determined before and after pharyngeal anesthesia with lidocaine. Pharyngeal anesthesia led to a 33% reduction in EMG(GG) activity (p<0.001), but NED worsened only by 3.6±5.8% (p=0.056). In conclusion, phasic EMG(GG) had little effect on NED. This finding suggests that individual differences in phasic EMG(GG) activation do not likely explain the variability in NED found among OSA patients.
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Affiliation(s)
- Pedro R Genta
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
| | - Robert L Owens
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Bradley A Edwards
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Danny J Eckert
- Neuroscience Research Australia (NeuRA) and the School of Medical Sciences, University of New South Wales, NSW 2052, Sydney, Australia
| | - James P Butler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Stephen H Loring
- Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Atul Malhotra
- Pulmonary and Critical Care Medicine, University of California San Diego, 9300 Campus Point Drive, La Jolla, CA 92037, USA
| | - Andrew C Jackson
- Department of Engineering, Boston University, 44 Cummington Mall, Boston, MA 02215, USA
| | - David P White
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
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Akoumianaki E, Maggiore SM, Valenza F, Bellani G, Jubran A, Loring SH, Pelosi P, Talmor D, Grasso S, Chiumello D, Guérin C, Patroniti N, Ranieri VM, Gattinoni L, Nava S, Terragni PP, Pesenti A, Tobin M, Mancebo J, Brochard L. The application of esophageal pressure measurement in patients with respiratory failure. Am J Respir Crit Care Med 2014; 189:520-31. [PMID: 24467647 DOI: 10.1164/rccm.201312-2193ci] [Citation(s) in RCA: 322] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
This report summarizes current physiological and technical knowledge on esophageal pressure (Pes) measurements in patients receiving mechanical ventilation. The respiratory changes in Pes are representative of changes in pleural pressure. The difference between airway pressure (Paw) and Pes is a valid estimate of transpulmonary pressure. Pes helps determine what fraction of Paw is applied to overcome lung and chest wall elastance. Pes is usually measured via a catheter with an air-filled thin-walled latex balloon inserted nasally or orally. To validate Pes measurement, a dynamic occlusion test measures the ratio of change in Pes to change in Paw during inspiratory efforts against a closed airway. A ratio close to unity indicates that the system provides a valid measurement. Provided transpulmonary pressure is the lung-distending pressure, and that chest wall elastance may vary among individuals, a physiologically based ventilator strategy should take the transpulmonary pressure into account. For monitoring purposes, clinicians rely mostly on Paw and flow waveforms. However, these measurements may mask profound patient-ventilator asynchrony and do not allow respiratory muscle effort assessment. Pes also permits the measurement of transmural vascular pressures during both passive and active breathing. Pes measurements have enhanced our understanding of the pathophysiology of acute lung injury, patient-ventilator interaction, and weaning failure. The use of Pes for positive end-expiratory pressure titration may help improve oxygenation and compliance. Pes measurements make it feasible to individualize the level of muscle effort during mechanical ventilation and weaning. The time is now right to apply the knowledge obtained with Pes to improve the management of critically ill and ventilator-dependent patients.
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Affiliation(s)
- Evangelia Akoumianaki
- 1 Department of Intensive Care Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece
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Loring SH, Talmor D. Inhomogeneous computed tomographic densities in lungs in acute respiratory distress syndrome: stress multipliers leading to ventilator-induced injury? Am J Respir Crit Care Med 2014; 189:123-4. [PMID: 24428645 DOI: 10.1164/rccm.201312-2189ed] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Stephen H Loring
- 1 Department of Anesthesia, Critical Care and Pain Medicine Beth Israel Deaconess Medical Center and Harvard Medical School Boston, Massachusetts
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Farhat MR, Loring SH, Riskind P, Weinhouse G. Disturbance of respiratory muscle control in a patient with early-stage multiple sclerosis. Eur Respir J 2014; 41:1454-6. [PMID: 23728406 DOI: 10.1183/09031936.00172312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Beitler JR, Shaefi S, Montesi SB, Devlin A, Loring SH, Talmor D, Malhotra A. Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis. Intensive Care Med 2014; 40:332-41. [PMID: 24435203 DOI: 10.1007/s00134-013-3194-3] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 12/09/2013] [Indexed: 02/07/2023]
Abstract
PURPOSE Prone positioning for ARDS has been performed for decades without definitive evidence of clinical benefit. A recent multicenter trial demonstrated for the first time significantly reduced mortality with prone positioning. This meta-analysis was performed to integrate these findings with existing literature and test whether differences in tidal volume explain conflicting results among randomized trials. METHODS Studies were identified using MEDLINE, EMBASE, Cochrane Register of Controlled Trials, LILACS, and citation review. Included were randomized trials evaluating the effect on mortality of prone versus supine positioning during conventional ventilation for ARDS. The primary outcome was risk ratio of death at 60 days meta-analyzed using random effects models. Analysis stratified by high (>8 ml/kg predicted body weight) or low (≤ 8 ml/kg PBW) mean baseline tidal volume was planned a priori. RESULTS Seven trials were identified including 2,119 patients, of whom 1,088 received prone positioning. Overall, prone positioning was not significantly associated with the risk ratio of death (RR 0.83; 95% CI 0.68-1.02; p = 0.073; I (2) = 64%). When stratified by high or low tidal volume, prone positioning was associated with a significant decrease in RR of death only among studies with low baseline tidal volume (RR 0.66; 95% CI 0.50-0.86; p = 0.002; I (2) = 25%). Stratification by tidal volume explained over half the between-study heterogeneity observed in the unstratified analysis. CONCLUSIONS Prone positioning is associated with significantly reduced mortality from ARDS in the low tidal volume era. Substantial heterogeneity across studies can be explained by differences in tidal volume.
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Affiliation(s)
- Jeremy R Beitler
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, 221 Longwood Avenue, BLI 036, Boston, MA, 02115, USA,
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O'Donnell CR, Bankier AA, O'Donnell DH, Loring SH, Boiselle PM. Static end-expiratory and dynamic forced expiratory tracheal collapse in COPD. Clin Radiol 2013; 69:357-62. [PMID: 24361144 DOI: 10.1016/j.crad.2013.11.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/23/2013] [Accepted: 11/05/2013] [Indexed: 11/15/2022]
Abstract
AIM To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT). MATERIALS AND METHODS After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves. RESULTS Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10-50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was <0.3. CONCLUSION COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse.
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Affiliation(s)
- C R O'Donnell
- Department of Pulmonary, Critical Care and Sleep Medicine, Harvard Medical School, Boston, MA, USA.
| | - A A Bankier
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - D H O'Donnell
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - S H Loring
- Department of Anesthesia, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, MA, USA
| | - P M Boiselle
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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Henderson LA, Loring SH, Dellaripa PF, Nigrovic PA. Dr. Henderson, et al reply. J Rheumatol 2013; 40:1926. [PMID: 24344358 DOI: 10.3899/jrheum.130897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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Sarge T, Loring SH, Yitsak-Sade M, Malhotra A, Novack V, Talmor D. Raising positive end-expiratory pressures in ARDS to achieve a positive transpulmonary pressure does not cause hemodynamic compromise. Intensive Care Med 2013; 40:126-8. [PMID: 24126673 DOI: 10.1007/s00134-013-3127-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 09/27/2013] [Indexed: 11/25/2022]
Affiliation(s)
- Todd Sarge
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Dana 717, Boston, MA, 02215, USA
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Boiselle PM, Litmanovich DE, Michaud G, Roberts DH, Loring SH, Womble HM, Millett ME, O'Donnell CR. Dynamic Expiratory Tracheal Collapse in Morbidly Obese COPD Patients. COPD 2013; 10:604-10. [DOI: 10.3109/15412555.2013.781149] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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36
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Boiselle PM, Michaud G, Roberts DH, Loring SH, Womble HM, Millett ME, O'Donnell CR. Dynamic expiratory tracheal collapse in COPD: correlation with clinical and physiologic parameters. Chest 2013; 142:1539-1544. [PMID: 22722230 DOI: 10.1378/chest.12-0299] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND COPD has been described as a risk factor for excessive expiratory tracheal collapse, but its prevalence and clinical correlates have not been fully determined. The purpose of this study is to prospectively determine the prevalence of excessive expiratory tracheal collapse among patients with COPD and to test the hypothesis that clinical and/or physiologic parameters will correlate with the presence of excessive tracheal collapse. METHODS We studied 100 adults meeting GOLD (Global Initiative for Obstructive Lung Disease) criteria for COPD, who underwent full pulmonary function tests (PFTs), 6-min walk test (6MWT), St. George's Respiratory Questionnaire (SGRQ), and low-dose CT scan at total lung capacity and during dynamic exhalation with spirometric monitoring. We examined correlations between percentage dynamic expiratory tracheal collapse and PFTs, 6MWT distance, and SGRQ scores. RESULTS Patients included 48 women and 52 men with mean age 65 ± 7 years, FEV₁ 64% ± 22% predicted, and percentage expiratory collapse 59% ± 19%. Twenty of 100 participants met study criteria for excessive expiratory collapse. There was no significant correlation between percentage expiratory tracheal collapse and any pulmonary function measure, total SGRQ score, or 6MWT distance. The SGRQ symptom subscale was weakly correlated with percentage collapse of the mid trachea (R = 0.215, P = .03). CONCLUSIONS Excessive expiratory tracheal collapse is observed in a subset of patients with COPD, but the magnitude of collapse is independent of disease severity and does not correlate significantly with physiologic parameters. Thus, the incidental identification of excessive expiratory tracheal collapse in a general COPD population may not necessarily be clinically significant.
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Affiliation(s)
- Phillip M Boiselle
- Center for Airway Imaging and the Departments of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA.
| | - Gaetane Michaud
- Department of Interventional Pulmonology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - David H Roberts
- Department of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Hilary M Womble
- Department of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Mary E Millett
- Center for Airway Imaging and the Departments of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Carl R O'Donnell
- Department of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
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37
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Pecchiari M, Loring SH, D’Angelo E. Esophageal pressure as an estimate of average pleural pressure with lung or chest distortion in rats. Respir Physiol Neurobiol 2013; 186:229-35. [DOI: 10.1016/j.resp.2013.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 01/30/2013] [Accepted: 02/01/2013] [Indexed: 01/18/2023]
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Henderson LA, Loring SH, Gill RR, Liao KP, Ishizawar R, Kim S, Perlmutter-Goldenson R, Rothman D, Son MBF, Stoll ML, Zemel LS, Sandborg C, Dellaripa PF, Nigrovic PA. Shrinking lung syndrome as a manifestation of pleuritis: a new model based on pulmonary physiological studies. J Rheumatol 2013; 40:273-81. [PMID: 23378468 DOI: 10.3899/jrheum.121048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The pathophysiology of shrinking lung syndrome (SLS) is poorly understood. We sought to define the structural basis for this condition through the study of pulmonary mechanics in affected patients. METHODS Since 2007, most patients evaluated for SLS at our institutions have undergone standardized respiratory testing including esophageal manometry. We analyzed these studies to define the physiological abnormalities driving respiratory restriction. Chest computed tomography data were post-processed to quantify lung volume and parenchymal density. RESULTS Six cases met criteria for SLS. All presented with dyspnea as well as pleurisy and/or transient pleural effusions. Chest imaging results were free of parenchymal disease and corrected diffusing capacities were normal. Total lung capacities were 39%-50% of predicted. Maximal inspiratory pressures were impaired at high lung volumes, but not low lung volumes, in 5 patients. Lung compliance was strikingly reduced in all patients, accompanied by increased parenchymal density. CONCLUSION Patients with SLS exhibited symptomatic and/or radiographic pleuritis associated with 2 characteristic physiological abnormalities: (1) impaired respiratory force at high but not low lung volumes; and (2) markedly decreased pulmonary compliance in the absence of identifiable interstitial lung disease. These findings suggest a model in which pleural inflammation chronically impairs deep inspiration, for example through neural reflexes, leading to parenchymal reorganization that impairs lung compliance, a known complication of persistently low lung volumes. Together these processes could account for the association of SLS with pleuritis as well as the gradual symptomatic and functional progression that is a hallmark of this syndrome.
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Affiliation(s)
- Lauren A Henderson
- Division of Immunology, Boston Children's Hospital, Boston, MA 02115, USA
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Abstract
Esophageal pressure (P(Es)) can be used to approximate pleural pressure (P(pl)) and might be clinically useful, particularly in the obese e.g., to guide mechanical ventilator settings in critical illness. However, mediastinal artifact (the difference between true P(pl) and P(Es)) may limit acceptance of the measurement, and reproducibility of P(Es) measurements remains unknown. Therefore, we aimed to assess the effect of body posture on P(Es) in a cohort of obese, but healthy subjects, some of whom had multiple measurements, to address the clinical robustness of esophageal manometry. Twenty-five overweight and obese subjects (BMI > 25 kg/m(2)) and 11 control lean subjects (BMI < 25 kg/m(2)) underwent esophageal manometry with pressures measured seated and supine. Twenty overweight and obese subjects had measurements repeated after ~1 to 2 weeks. Anthropometric data and sitting and supine spirometry were recorded. The average end-expiratory P(Es) sitting and supine were greater in the overweight and obese group than the lean group (sitting -0.1 ± 2.1 vs. -3.3 ± 1.2 cm H(2)O, supine 9.3 ± 3.3 vs. 6.9 ± 2.8 cm H(2)O, respectively). The mean differences between repeated measurements were small (-0.3 ± 1.7 cm H(2)O sitting and -0.1 ± 1.5 cm H(2)O supine). P(Es) correlated with a number of anthropometric and spirometric variables. In conclusion, P(Es) are slightly greater in overweight and obese subjects than lean subjects; but changes with position are similar in both groups. These data indicate that mediastinal weight and postural effects on P(Es) are within a clinically acceptable range, and suggest that esophageal manometry can be used to inform clinical decision making across wide range of body types.
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Affiliation(s)
- Robert L Owens
- Sleep Disorders Research Program, Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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40
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Sun Y, Butler JP, Ferrigno M, Albert MS, Loring SH. "Ventilatory alternans": a left-right alternation of inspiratory airflow in humans. Respir Physiol Neurobiol 2012; 185:468-71. [PMID: 23142365 DOI: 10.1016/j.resp.2012.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 10/17/2012] [Accepted: 10/29/2012] [Indexed: 11/29/2022]
Abstract
In a study visualizing ventilation with hyperpolarized (3)He magnetic resonance imaging (MRI) in elite breath hold divers, the dynamic MRI images in one subject exhibited an apparent alternation of the image intensity between left and right lung. We hypothesized that the alternation resulted from alternating variations in inspiratory flow rate to left and right lungs. Analysis showed that the alternation was not due to random uncorrelated temporal fluctuations of intensity (p<0.001). The frequency of alternation was approximately 56 min(-1), suggesting a cardiac origin. Similar alternation of ventilation was confirmed retrospectively in 4 of 6 additional subjects. These observations are consistent with previous studies showing cardiogenic mixing of gas in the lung. We speculate that cardiogenic pendelluft, possibly from ballistic lateral motion of the beating heart, could cause alternating variations of inspiratory flow to the lungs.
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Affiliation(s)
- Yanping Sun
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, United States
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O'Donnell CR, Litmanovich D, Loring SH, Boiselle PM. Age and sex dependence of forced expiratory central airway collapse in healthy volunteers. Chest 2012; 142:168-174. [PMID: 22194588 DOI: 10.1378/chest.11-2361] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND A recent estimate for the normal range of forced expiratory tracheal collapse differs substantially from that in an earlier study performed with comparable measurement methods. Given differences in subject characteristics between the two samples, we hypothesized that these discrepant findings may reflect a heretofore unrecognized association between forced expiratory tracheal collapse and age or sex. METHODS We enrolled 40 female and 41 male healthy volunteers between 25 and 75 years of age who were without respiratory symptoms or known risk factors for tracheomalacia. Subjects underwent low-dose CT scanning at total lung capacity (TLC) and during forced exhalation (Expdyn) with spirometric monitoring and coaching. Percentage forced expiratory collapse was regressed on age for the total sample and separately within sex. RESULTS Mean tracheal cross-sectional area (CSA) was 2.54 cm(2) ± 0.57 cm(2) at TLC and 1.15 cm(2) ± 0.53 cm(2) at Expdyn. Mean percentage forced expiratory collapse (%collapse) was 54% ± 20%. Men aged 24 to 31 years (n = 12) had mean %collapse of 36% ± 19%, comparable to results previously reported for similarly aged men (35% ± 18%). Men, but not women, showed a significant positive correlation (R(2) = 0.40, P < .001) between %collapse and age. Older men had both greater CSA at TLC (P = .02) and smaller CSA at Expdyn (P = .001) than younger men. CONCLUSIONS Men exhibit positive age dependence of forced expiratory tracheal collapse. The influence of age and sex on forced expiratory tracheal collapse should be considered in the diagnostic evaluation of expiratory dynamic airway collapse and/or tracheomalacia.
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Affiliation(s)
- Carl R O'Donnell
- Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA.
| | - Diana Litmanovich
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Phillip M Boiselle
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
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Abstract
A 33-year-old woman underwent a right-sided pneumonectomy in 1995 for treatment of a lung adenocarcinoma. As expected, there was an abrupt decrease in her vital capacity, but unexpectedly, it increased during the subsequent 15 years. Serial computed tomographic (CT) scans showed progressive enlargement of the remaining left lung and an increase in tissue density. Magnetic resonance imaging (MRI) with the use of hyperpolarized helium-3 gas showed overall acinar-airway dimensions that were consistent with an increase in the alveolar number rather than the enlargement of existing alveoli, but the alveoli in the growing lung were shallower than in normal lungs. This study provides evidence that new lung growth can occur in an adult human.
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Affiliation(s)
- James P Butler
- Division of Sleep Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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Engelberts D, Malhotra A, Butler JP, Topulos GP, Loring SH, Kavanagh BP. Relative effects of negative versus positive pressure ventilation depend on applied conditions. Intensive Care Med 2012; 38:879-85. [PMID: 22349427 DOI: 10.1007/s00134-012-2512-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 01/20/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE Comparisons of negative versus positive pressure ventilation have imperfectly matched the pressure-time profile or the lung volume history, or have incompletely applied in vivo negative pressure to include the complete thoracic wall and abdomen. HYPOTHESIS Negative pressure exerts the same pattern of lung distension as positive pressure when the pressure-time and volume history profiles are identical and the application of negative pressure is over the whole lung. METHODS (1) In isolated (ex vivo) and (2) intact (in vivo) mouse lungs (n = 4/group) (sealed chamber enclosing either the whole lung or whole mouse except for external airway opening), identical and inverse-tidal, square-wave pressure-time profiles were obtained with positive and negative pressure ventilation. (3) Following an identical volume history, surfactant-depleted rabbits (n = 7) were randomly assigned to sustained, static equivalent positive versus negative pressures. (4) Surfactant-depleted anesthetized rabbits (n = 10) with identical volume histories were randomized to positive versus negative ventilation with identical pressure-time characteristics. RESULTS Matched positive and negative pressure time profiles in ex vivo and in vivo mice resulted in identical tidal volumes. Identical (negative vs. positive) sustained static pressures resulted in similar PaO(2) and end expiratory lung volumes. Positive and negative ventilation with identical volume histories and pressure time characteristics showed no difference in oxygenation or lung volumes. Historical comparisons suggested better oxygenation with negative pressure when the volume history was not identical. CONCLUSIONS These data do not support major biological differences between negative and positive pressure ventilation when waveforms and lung volume history are matched.
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Affiliation(s)
- Doreen Engelberts
- Program in Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada
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Fahlman A, Loring SH, Ferrigno M, Moore C, Early G, Niemeyer M, Lentell B, Wenzel F, Joy R, Moore MJ. Static inflation and deflation pressure-volume curves from excised lungs of marine mammals. ACTA ACUST UNITED AC 2012; 214:3822-8. [PMID: 22031747 DOI: 10.1242/jeb.056366] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Excised lungs from eight marine mammal species [harp seal (Pagophilus groenlandicus), harbor seal (Phoca vitulina), gray seal (Halichoerus grypush), Atlantic white-sided dolphin (Lagenorhynchus acutus), common dolphin (Delphinus delphis), Risso's dolphin (Grampus griseus), long-finned pilot whale (Globicephala melas) and harbor porpoise (Phocoena phocoena)] were used to determine the minimum air volume of the relaxed lung (MAV, N=15), the elastic properties (pressure-volume curves, N=24) of the respiratory system and the total lung capacity (TLC). Our data indicate that mass-specific TLC (sTLC, l kg(-1)) does not differ between species or groups (odontocete vs phocid) and agree with that estimated (TLC(est)) from body mass (M(b)) by applying the equation: TLC(est)=0.135 M(b)(0.92). Measured MAV was on average 7% of TLC, with a range from 0 to 16%. The pressure-volume curves were similar among species on inflation but diverged during deflation in phocids in comparison with odontocetes. These differences provide a structural basis for observed species differences in the depth at which lungs collapse and gas exchange ceases.
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Affiliation(s)
- Andreas Fahlman
- Woods Hole Oceanographic Institution, 266 Woods Hole Road, MS 50, Woods Hole, MA 02543, USA.
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Kim JH, Butler JP, Loring SH. Probing softness of the parietal pleural surface at the micron scale. J Biomech 2011; 44:2558-64. [PMID: 21820660 PMCID: PMC3168578 DOI: 10.1016/j.jbiomech.2011.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 06/23/2011] [Accepted: 07/06/2011] [Indexed: 02/03/2023]
Abstract
The pleural surfaces of the chest wall and lung slide against each other, lubricated by pleural fluid. During sliding motion of soft tissues, shear induced hydrodynamic pressure deforms the surfaces, promoting uniformity of the fluid layer thickness, thereby reducing friction. To assess pleural deformability at length scales comparable to pleural fluid thickness, we measured the modulus of the parietal pleura of rat chest wall using atomic force microscopy (AFM) to indent the pleural surface with spheres (radius 2.5 and 5 μm). The pleura exhibited two distinct indentation responses depending on location, reflecting either homogeneous or significantly heterogeneous tissue properties. We found an elastic modulus of 0.38-0.95 kPa, lower than the values measured using flat-ended cylinders >100 μm radii (Gouldstone et al., 2003, Journal of Applied Physiology 95, 2345-2349). Interestingly, the pleura exhibited a three-fold higher modulus when probed using 2.5 vs. 5 μm spherical tips at the same normalized depth, confirming depth dependent inhomogeneous elastic properties. The observed softness of the pleura supports the hypothesis that unevenness of the pleural surface on this scale is smoothed by local hydrodynamic pressure.
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Affiliation(s)
- Jae Hun Kim
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave., Dana 715, Boston, MA 02215, USA.
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Diaz AA, Come CE, Ross JC, San José Estépar R, Han MK, Loring SH, Silverman EK, Washko GR. Association between airway caliber changes with lung inflation and emphysema assessed by volumetric CT scan in subjects with COPD. Chest 2011; 141:736-744. [PMID: 21940776 DOI: 10.1378/chest.11-1026] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND An increase in airway caliber (airway distensibility) with lung inflation is attenuated in COPD. Furthermore, some subjects have a decrease in airway caliber with lung inflation. We aimed to test the hypothesis that airway caliber increases are lower in subjects with emphysema-predominant (EP) compared with airway-predominant (AP) CT scan subtypes. Additionally, we compared clinical and CT scan features of subjects with (airway constrictors) and without a decrease in airway caliber. METHODS Based on GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages and CT scan subtypes, we created a control group (n = 46) and the following matched COPD groups (n = 23 each): GOLD-2-AP, GOLD-2-EP, GOLD-4-AP, and GOLD-4-EP. From the CT scans of all 138 subjects, we measured emphysema, lung volumes, and caliber changes in the third and fourth airway generations of two bronchi. We expressed airway distensibility (ratio of airway lumen diameter change to lung volume change from end tidal breathing to full inspiration) as a global or lobar measure based on normalization by whole-lung or lobar volume changes. RESULTS Global distensibility in the third and fourth airway generations was significantly lower in the GOLD-2-EP and GOLD-4-EP groups than in control subjects. In GOLD-2 subjects, lobar distensibility of the right-upper-lobe fourth airway generation was significantly lower in those with EP than in those with AP. In multivariate analysis, emphysema was an independent determinant of global and lobar airway distensibility. Compared with nonconstrictors, airway constrictors experienced more dyspnea, were more hyperinflated, and had a higher percentage of emphysema. CONCLUSIONS Distensibility of large- to medium-sized airways is reduced in subjects with an EP CT scan subtype. Emphysema seems to alter airway-parenchyma interdependence. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov.
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Affiliation(s)
- Alejandro A Diaz
- Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Department of Pulmonary Diseases, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Carolyn E Come
- Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - James C Ross
- Surgical Planning Laboratory, Laboratory of Mathematics in Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, MA
| | - Raúl San José Estépar
- Surgical Planning Laboratory, Laboratory of Mathematics in Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, MA
| | - MeiLan K Han
- Pulmonary and Critical Care, University of Michigan School of Medicine, Ann Arbor, MI
| | - Stephen H Loring
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Edwin K Silverman
- Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Channing Laboratory, Brigham and Women's Hospital, Boston, MA
| | - George R Washko
- Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
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Kim JH, Butler JP, Loring SH. Influence of the softness of the parietal pleura on respiratory sliding mechanisms. Respir Physiol Neurobiol 2011; 177:114-9. [PMID: 21473935 DOI: 10.1016/j.resp.2011.03.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/25/2011] [Accepted: 03/30/2011] [Indexed: 10/18/2022]
Abstract
The pleural surfaces of the lung and chest wall slide against each other with low friction. Normal load support can be effected either by a combination of quasi-static fluid pressure and solid-solid contacts of relatively stiff asperities, or by shear-induced hydrodynamic pressures in the pleural fluid layer. To distinguish between these mechanisms, we measured surface topography and spatial distribution of stiffness of rat parietal pleura using atomic force microscopy. The topography of the pleural surface has unevenness at length scales smaller than the thickness of pleural fluid, similar to mesothelial cell diameters. The estimated maximum normal contact pressure that could be borne by asperities of the soft pleura is much less than that required to support a substantial difference between pleural fluid pressure and the pleural surface pressure. These results suggest that during sliding motion, unevenness of the pleural surface is smoothed by local hydrodynamic pressure, preventing any significant contribution of solid-solid contacts.
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Affiliation(s)
- Jae Hun Kim
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
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Litmanovich D, O’Donnell CR, Bankier AA, Ernst A, Millett ME, Loring SH, Boiselle PM. Bronchial Collapsibility at Forced Expiration in Healthy Volunteers: Assessment with Multidetector CT. Radiology 2010; 257:560-7. [DOI: 10.1148/radiol.10100219] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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