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Stepwise Ventilator Waveform Assessment to Diagnose Pulmonary Pathophysiology. Anesthesiology 2022; 137:85-92. [PMID: 35511174 DOI: 10.1097/aln.0000000000004220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Clinicians can use mechanical waveform analysis as a diagnostic tool to identify pulmonary pathophysiology. This review offers an approach to develop a hypothesis of a patient’s lung pathophysiology.
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Pearson SD, Koyner JL, Patel BK. Management of Respiratory Failure: Ventilator Management 101 and Noninvasive Ventilation. Clin J Am Soc Nephrol 2022; 17:572-580. [PMID: 35273008 PMCID: PMC8993478 DOI: 10.2215/cjn.13091021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mechanical ventilation is a lifesaving therapy for critically ill patients with respiratory failure, but like all treatments, it has the potential to cause harm if not administered appropriately. This review aims to give an overview of the basic principles of invasive and noninvasive mechanical ventilation. Topics covered include modes of mechanical ventilation, respiratory mechanics and ventilator waveform interpretation, strategies for initial ventilator settings, indications and contraindications for noninvasive ventilation, and the effect of the ventilator on kidney function.
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Affiliation(s)
- Steven D Pearson
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, Illinois
| | - Jay L Koyner
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, Illinois
| | - Bhakti K Patel
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, Illinois
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3
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Vitacca M, Ceriana P, Prediletto I, Carlucci A, Paneroni M, Ambrosino N, Nava S. Intrinsic Dynamic Positive End-Expiratory Pressure in Stable Patients with Chronic Obstructive Pulmonary Disease. Respiration 2020; 99:1129-1135. [PMID: 33271563 DOI: 10.1159/000511266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/31/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Assessment of intrinsic dynamic positive end-expiratory pressure (PEEPi,dyn) may be clinically important in stable patients with chronic obstructive pulmonary disease (COPD), but epidemiological data are scant. OBJECTIVES The aim of our study was (i) to assess the PEEPi,dyn in a large population of stable patients with COPD and (ii) to evaluate the correlations with some noninvasive measurements routinely assessed. METHOD Retrospective analysis of lung mechanics, dynamic volumes, arterial blood gases, dyspnoea by means of the Medical Research Council (MRC) scale, the COPD Assessment Test score, and maximal inspiratory/expiratory pressures in 87 hypercapnic and 62 normocapnic patients. RESULTS The mean PEEPi,dyn was significantly higher in hypercapnic than normocapnic patients (2.8 ± 2.2 vs. 1.9 ± 1.6 cm H2O, respectively, p = 0.0094). PEEPi,dyn did not differ according to Global Initiative for Chronic Obstructive Lung Disease stage, MRC score, or use or not of long-term oxygen therapy. There were significant although weak correlations between PEEPi,dyn and airway obstruction, hyperinflation, respiratory muscle function, arterial CO2 tension, and number of exacerbations/year. The transdiaphragmatic pressure was the strongest variable associated to PEEPi,dyn (R = 0.5713, p = 0.001). CONCLUSION In stable patients with COPD, PEEPi,dyn is higher in hypercapnic patients and weakly correlated to noninvasive measures of lung and respiratory muscle function.
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Affiliation(s)
- Michele Vitacca
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Brescia, Italy,
| | - Piero Ceriana
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Pavia, Pavia, Italy
| | - Irene Prediletto
- Università Alma Mater, Cattedra di Malattie dell'Apparato Respiratorio, Bologna, Italy
| | - Annalisa Carlucci
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Pavia, Pavia, Italy.,Università dell'Insubria, Dipartimento di Medicina e Chirurgia, Varese-Como, Italy
| | - Mara Paneroni
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Brescia, Italy
| | - Nicolino Ambrosino
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Montescano, Pavia, Italy
| | - Stefano Nava
- Università Alma Mater, Cattedra di Malattie dell'Apparato Respiratorio, Bologna, Italy
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Xavier G, Melo-Silva CA, Santos CEVGD, Amado VM. Accuracy of chest auscultation in detecting abnormal respiratory mechanics in the immediate postoperative period after cardiac surgery. ACTA ACUST UNITED AC 2019; 45:e20180032. [PMID: 31365614 PMCID: PMC6715162 DOI: 10.1590/1806-3713/e20180032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 12/07/2018] [Indexed: 11/23/2022]
Abstract
Objective: To investigate the accuracy of chest auscultation in detecting abnormal respiratory mechanics. Methods: We evaluated 200 mechanically ventilated patients in the immediate postoperative period after cardiac surgery. We assessed respiratory system mechanics - static compliance of the respiratory system (Cst,rs) and respiratory system resistance (R,rs) - after which two independent examiners, blinded to the respiratory system mechanics data, performed chest auscultation. Results: Neither decreased/abolished breath sounds nor crackles were associated with decreased Cst,rs (≤ 60 mL/cmH2O), regardless of the examiner. The overall accuracy of chest auscultation was 34.0% and 42.0% for examiners A and B, respectively. The sensitivity and specificity of chest auscultation for detecting decreased/abolished breath sounds or crackles were 25.1% and 68.3%, respectively, for examiner A, versus 36.4% and 63.4%, respectively, for examiner B. Based on the judgments made by examiner A, there was a weak association between increased R,rs (≥ 15 cmH2O/L/s) and rhonchi or wheezing (ϕ = 0.31, p < 0.01). The overall accuracy for detecting rhonchi or wheezing was 89.5% and 85.0% for examiners A and B, respectively. The sensitivity and specificity for detecting rhonchi or wheezing were 30.0% and 96.1%, respectively, for examiner A, versus 10.0% and 93.3%, respectively, for examiner B. Conclusions: Chest auscultation does not appear to be an accurate diagnostic method for detecting abnormal respiratory mechanics in mechanically ventilated patients in the immediate postoperative period after cardiac surgery.
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Affiliation(s)
- Glaciele Xavier
- . Laboratório de Fisiologia Respiratória, Universidade de Brasília, Brasília (DF) Brasil.,. Instituto de Cardiologia do Distrito Federal, Brasília (DF) Brasil
| | - César Augusto Melo-Silva
- . Laboratório de Fisiologia Respiratória, Universidade de Brasília, Brasília (DF) Brasil.,. Divisão de Fisioterapia, Hospital Universitário de Brasília, Brasília (DF) Brasil
| | - Carlos Eduardo Ventura Gaio Dos Santos
- . Laboratório de Fisiologia Respiratória, Universidade de Brasília, Brasília (DF) Brasil.,. Divisão de Pneumologia, Hospital Universitário de Brasília, Brasília (DF) Brasil
| | - Veronica Moreira Amado
- . Laboratório de Fisiologia Respiratória, Universidade de Brasília, Brasília (DF) Brasil.,. Divisão de Pneumologia, Hospital Universitário de Brasília, Brasília (DF) Brasil
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5
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Davidson AC, Banham S, Elliott M, Kennedy D, Gelder C, Glossop A, Church AC, Creagh-Brown B, Dodd JW, Felton T, Foëx B, Mansfield L, McDonnell L, Parker R, Patterson CM, Sovani M, Thomas L. BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults. Thorax 2016; 71 Suppl 2:ii1-35. [DOI: 10.1136/thoraxjnl-2015-208209] [Citation(s) in RCA: 195] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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6
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Hodder R. Critical care in the ED: potentially fatal asthma and acute lung injury syndrome. Open Access Emerg Med 2012; 4:53-68. [PMID: 27147862 PMCID: PMC4753975 DOI: 10.2147/oaem.s30998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Emergency department clinicians are frequently called upon to assess, diagnose, and stabilize patients who present with acute respiratory failure. This review describes a rapid initial approach to acute respiratory failure in adults, illustrated by two common examples: (1) an airway disease - acute potentially fatal asthma, and (2) a pulmonary parenchymal disease - acute lung injury/acute respiratory distress syndrome. As such patients are usually admitted to hospital, discussion will be focused on those initial management aspects most relevant to the emergency department clinician.
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Affiliation(s)
- Rick Hodder
- Divisions of Pulmonary and Critical Care, University of Ottawa and The Ottawa Hospital, Ottawa, Canada
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7
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Abstract
Auto-positive end-expiratory pressure (PEEP) is a common but frequently unrecognized problem in critically ill patients. It has important physiologic consequences and can cause shock and cardiac arrest. Treatment consists of relieving expiratory airflow obstruction and reducing minute ventilation delivered by positive pressure ventilation. Sedation and fluid management are important adjunctive therapies. This analytic review discusses the prevalence, pathophysiology, and hemodynamic consequences of auto-PEEP and an approach to its treatment.
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Affiliation(s)
- David Berlin
- Division of Pulmonary and Critical Care Medicine, Weill Cornell Medical College, New York, NY, USA
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Nassar BS, Collett ND, Schmidt GA. The flow-time waveform predicts respiratory system resistance and compliance. J Crit Care 2012; 27:418.e7-14. [PMID: 22226421 DOI: 10.1016/j.jcrc.2011.10.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 09/28/2011] [Accepted: 10/31/2011] [Indexed: 02/09/2023]
Abstract
PURPOSE Knowledge of patients' lung compliance and resistance aids clinical management. We investigated whether these values, readily measured during volume assist-control ventilation (VACV), could also be estimated during pressure assist-control ventilation (PACV). METHODS Data were collected in 12 mechanically ventilated human subjects. During VACV, peak pressure, plateau pressure, end-expiratory pressure, tidal volume, and inspiratory flow rate were measured. During PACV, inspiratory pressure, end-expiratory pressure, and tidal volume were recorded. The linear component of the pressure-time waveform was extrapolated to time and flow axes. Using the equation of motion for the respiratory system, assuming a nonlinear resistance, we calculated inspiratory resistance and compliance. During VACV, compliance and inspiratory resistance were calculated in the conventional manner. RESULTS In ventilated subjects, mean compliance during PACV was 37.06 ± 15.65 mL/cm H(2)O, and during VACV, 36.93 ± 12.18 mL/cm H(2)O. Mean inspiratory resistance during PACV was 15.17 ± 5.14 cm H(2)O/L per second, whereas during VACV, it was 12.50 ± 2.99 cm H(2)O/L per second. A strong correlation is evident between compliance and inspiratory resistance calculated during PACV vs VACV (r(2) of 0.73 and 0.51, respectively). CONCLUSIONS During PACV, the inspiratory flow waveform is linear, and its slope contains information regarding inspiratory resistance and compliance. Calculated values correlate with those during VACV.
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Affiliation(s)
- Boulos S Nassar
- Division of Pulmonary, Critical Care, and Occupational Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
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Hodder R, Lougheed MD, FitzGerald JM, Rowe BH, Kaplan AG, McIvor RA. Management of acute asthma in adults in the emergency department: assisted ventilation. CMAJ 2010; 182:265-72. [PMID: 19901044 PMCID: PMC2826468 DOI: 10.1503/cmaj.080073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Rick Hodder
- The Ottawa Hospital, University of Ottawa, Ottawa, Ontario.
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10
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Manthous CA. Avoiding circulatory complications during endotracheal intubation and initiation of positive pressure ventilation. J Emerg Med 2009; 38:622-31. [PMID: 19464138 DOI: 10.1016/j.jemermed.2009.01.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 12/23/2008] [Accepted: 01/13/2009] [Indexed: 12/20/2022]
Abstract
BACKGROUND In many hospitals, emergency physicians commonly initiate invasive positive-pressure ventilation. OBJECTIVES To review common patient- and ventilator-related factors that can promote hemodynamic instability during and after endotracheal intubation. DISCUSSION Venous return is proportional to mean systemic pressure (Pms) minus right atrial pressure (Pra). Endotracheal intubation with positive-pressure ventilation often reduces Pms while always increasing Pra, so venous return inevitably decreases, resulting in hypotension in almost one-third of patients. This article reviews the pathophysiology of respiratory failure, the basic circulatory physiology associated with endotracheal intubation, and methods that may be helpful to reduce the frequency of intubation-related hypotension. CONCLUSION Although unproven, preventive measures taken before, during, and after endotracheal intubation are likely to minimize the frequency, magnitude, and duration of intubation-related hypotension.
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11
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Owens RL, Stigler WS, Hess DR. Do newer monitors of exhaled gases, mechanics, and esophageal pressure add value? Clin Chest Med 2008; 29:297-312, vi-vii. [PMID: 18440438 DOI: 10.1016/j.ccm.2008.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The current understanding of lung mechanics and ventilator-induced lung injury suggests that patients who have acute respiratory distress syndrome should be ventilated in such a way as to minimize alveolar over-distension and repeated alveolar collapse. Clinical trials have used such lung protective strategies and shown a reduction in mortality; however, there is data that these "one-size fits all" strategies do not work equally well in all patients. This article reviews other methods that may prove useful in monitoring for potential lung injury: exhaled breath condensate, pressure-volume curves, and esophageal manometry. The authors explore the concepts, benefits, difficulties, and relevant clinical trials of each.
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Affiliation(s)
- Robert L Owens
- Department of Medicine, Pulmonary and Critical Care Unit, Cox 2, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
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12
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Abstract
Over the past 2 decades, the art of "weaning" from mechanical ventilation has been informed by increasing published basic science and outcomes studies. Although monitoring technologies can provide vast amounts of information before, during, and after liberation from mechanical ventilation, little data exists on how to maximally harness even routinely monitored, basic physiologic parameters. Overdependence on technology and derived variables, without data to demonstrate benefit, may even inhibit the patient's progress if it is used inappropriately. We review the scientific evidence for best using routinely available physiologic data and a few more sophisticated and invasive monitoring technologies during weaning. We also suggest future study designs that would better inform the process of liberation from the ventilator and endotracheal extubation.
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Affiliation(s)
- Jonathan M Siner
- Section of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yale University School of Medicine, P.O. Box 208057, New Haven, CT 06520-8057, USA.
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Abstract
Acute respiratory failure is manifested clinically as a patient with variable degrees of respiratory distress, but characteristically an abnormal arterial blood partial pressure of oxygen or carbon dioxide. The application of mechanical ventilation in this setting can be life-saving. An emerging body of clinical and basic research, however, has highlighted the potential adverse effects of positive pressure ventilation. Clinicians involved with the care of critically ill patients must recognize and seek to prevent these complications using lung-protective ventilation strategies. This article discusses the basic concepts of mechanical ventilation, reviews the categories of ventilator-associated lung injury, and discusses current strategies for the recognition and prevention of these adverse effects in the application of mechanical ventilation.
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Affiliation(s)
- Michael Donahoe
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, 3459 Fifth Avenue, 628 NW, Pittsburgh, PA 15213, USA.
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Meyer NJ, Davis SQ, Kress JP. Acute tachypnea during mechanical ventilation in a 62-year-old man with multiple myeloma involving the spinal cord. Chest 2006; 130:616-9. [PMID: 16899869 DOI: 10.1378/chest.130.2.616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Nuala J Meyer
- Section of Pulmonary and Critical Care Medicine, University of Chicago, IL 60637, USA
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Abstract
Multiple perspectives must be considered when assessing the mechanically ventilated patient. Assessment begins before the advance practice nurse (APN) encounters the patient. Important information about the patient can be gleaned from the history, medications, and social history. The APN then observes the patient to determine if patient-ventilator synchrony has been achieved. Physical findings are gathered and correlated with the chest radiogram. Data from the ventilator are evaluated to assess compliance, minute ventilation, tidal volume, and other parameters that will assist in the evaluation of the patient's needs. Electrolytes, acid-base state, and nutrition must all be considered to obtain a complete assessment of these patients. From all these data points, the APN can develop a detailed plan of care that will enhance positive patient outcomes.
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Affiliation(s)
- Adam C Winters
- Asheville Pulmonary & Critical Care Associates, PA, Asheville, NC 28801, USA.
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16
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Abstract
All asthmatics regardless of their perceived severity, are at risk of exacerbation, particularly if they are suboptimally treated in the outpatient arena. Fortunately most patients recover after administration of bronchodilators and anti-inflammatory medications, but preventable deaths continue to occur and refractory cases result in hospitalization and need for mechanical ventilation. We begin this article by reviewing the pathophysiology of acute exacerbations to build a foundation for the assessment of clinical status and to provide the rationale for a carefully contemplated and evidence-based therapeutic approach. We end this article with an in-depth examination of the particular problems that are encountered during mechanical ventilation and offer a strategy that helps minimize complications. In the final analysis, however, the greatest gains in the field of acute asthma will come not from its treatment but from its prevention by enhanced educational and environmental efforts and by the delivery of optimal medications at home.
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Affiliation(s)
- Susan J Corbridge
- College of Nursing, University of Illinois at Chicago and University of Illinois at Chicago Medical Center, Chicago 60612, USA.
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17
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Wang SH, Wei TS. The outcome of early pressure-controlled inverse ratio ventilation on patients with severe acute respiratory distress syndrome in surgical intensive care unit. Am J Surg 2002; 183:151-5. [PMID: 11918879 DOI: 10.1016/s0002-9610(01)00870-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Pressure-controlled inverse ratio ventilation (PC-IRV) was used in patients with acute respiratory distress syndrome (ARDS) after failed volume-cycled conventional ratio ventilation (VC-CRV). The aim of this study was to evaluate the outcome of early PC-IRV in severe ARDS. METHODS Twenty patients with severe ARDS were switched from VC-CRV to PC-IRV if they failed to maintain SaO(2) >90% by the following criteria: peak inspiratory pressure (PIP) >35 cm H(2)O, FIO(2) = 60%, and positive end-expiratory pressure (PEEP) 10 cm H(2)O. RESULTS The values of PIP, mean airway pressure, minute volumes, and lung injury score in VC-CRV were 43.9 +/- 8.0 cm H(2)O, 19.5 +/- 6.4 cm H(2)O, 11.0 +/- 2.1 L/min, and 2.8 +/- 0.2 respectively. In PC-IRV, the corresponding data were 31.8 +/- 5.1 cm H(2)O, 25.4 +/- 4.6 cm H(2)O, 8.3 +/- 0.9 L/min, and 2.5 +/- 0.4. All of these parameters were significantly different. Fifteen patients (75%) survived their intensive care unit stay. CONCLUSIONS Early PC-IRV in severe ARDS improves oxygenation, facilitates tapering of high fraction of inspiratory oxygen, and decreases high PEEP or PIP, and then results in the improvement of the patient's outcome.
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Affiliation(s)
- Shu-Hui Wang
- Critical Care Division, Surgical Department, Changhua Christian Hospital, Taiwan.
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Bremner HR, Freywald T, O'Brodovich HM, Otulakowski G. Promoter analysis of the gene encoding the beta-subunit of the rat amiloride-sensitive epithelial sodium channel. Am J Physiol Lung Cell Mol Physiol 2002; 282:L124-34. [PMID: 11741824 DOI: 10.1152/ajplung.2002.282.1.l124] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The amiloride-sensitive epithelial Na(+) channel (ENaC), found in the apical membrane of Na(+)-absorptive epithelia, is made up of three differentially regulated subunits: alpha, beta, and gamma. We undertook a study of the 5'-end of the gene encoding the beta-ENaC subunit in the rat. 5'-Rapid amplification of cDNA ends and RNase protection assays indicated multiple transcription start sites over a 50-bp region. Sequencing 1.3 kb of the 5'-flanking DNA revealed putative binding sites for PEA3, Sp1, activator protein (AP)-1 and Oct-1 but neither a TATA box nor consensus sites for steroid hormone receptor binding. Transient transfections of reporter constructs driven by beta-ENaC 5'-flanking DNA in the representative epithelial cell lines Madin-Darby canine kidney, MLE-15, and Caco-2 revealed a negative element present between positions -424 and -311 that affected basal transcription rates. Gel shift assays showed protein-DNA binding activity of an AP-1 consensus site in this region; however, mutation of the AP-1 site did not abrogate the repressive activity of the region in transient transfections. Deletion of two clusters of Sp1 consensus binding sites between -1 and -51 bp and between -169 and -211 bp indicated that the proximal cluster was essential to basal promoter activity in transfected cell lines. In a comparison of these data with those in published studies on alpha- and gamma-ENaC promoters, the beta- and gamma-subunit promoters appear to be more similar to each other than to the alpha-promoter.
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Affiliation(s)
- Harry Robert Bremner
- Canadian Institutes of Health Research Group in Lung Development, Lung Biology Programme, Research Institute, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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19
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Abstract
Exacerbations of COPD are a leading indication for MV in the intensive care unit. A thorough understanding of the pathophysiology of AVF in COPD is critical for physicians caring for these patients. In particular, physicians should understand DHI and use the ventilator and ancillary techniques to minimize its impact. Noninvasive positive-pressure ventilation should be considered strongly in relatively stable patients with an adequate mental status and manageable secretions. Once AVF resolves, patients should be removed from the ventilator as soon as is safe to do so to minimize the adverse effects of prolonged MV. An organized approach to weaning and identifying patients capable of independent breathing is crucial. Most patients with COPD and AVF benefit from MV and generally return to or approach their premorbid functional status. A significant subset, however, will not benefit from, or choose not to undergo, MV. Deciding upon appropriate therapeutic options for these patients relies heavily on effective communication between physician and patient. Comprehensive discussions before the development of AVF can assist decision-making after respiratory failure develops.
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Affiliation(s)
- J M Sethi
- Department of Medicine, Section of Pulmonary and Critical Care, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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20
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Vitacca M, Nava S, Confalonieri M, Bianchi L, Porta R, Clini E, Ambrosino N. The appropriate setting of noninvasive pressure support ventilation in stable COPD patients. Chest 2000; 118:1286-93. [PMID: 11083676 DOI: 10.1378/chest.118.5.1286] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVE To evaluate the short-term physiologic effects of two settings of nasal pressure-support ventilation (NPSV) in stable COPD patients with chronic hypercapnia. DESIGN Randomized controlled physiologic study. SETTING Lung function units and outpatient clinic of two affiliated pulmonary rehabilitation centers. PATIENTS Twenty-three patients receiving domiciliary nocturnal NPSV for a mean (+/- SD) duration of 31 +/- 20 months. METHODS Evaluation of arterial blood gases, breathing pattern, respiratory muscles, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) during both unassisted and assisted ventilation. Two settings of NPSV were randomly applied for 30 min each: (1) usual setting (U), the setting of NPSV actually used by the individual patient at home; and (2) physiologic setting (PHY), the level of inspiratory pressure support (IPS) and external positive end-expiratory pressure (PEEPe) tailored to patient according to invasive evaluation of respiratory muscular function and mechanics. RESULTS All patients tolerated NPSV well throughout the procedure. Mean U was IPS, 16 +/- 3 cm H(2)O and PEEPe, 3.6 +/- 1.4 cm H(2)O; mean PHY was IPS, 15 +/- 3 cm H(2)O and PEEPe, 3.1 +/- 1.6 cm H(2)O. NPSV was able to significantly (p < 0.01) improve arterial blood gases independent of the setting applied. When compared with spontaneous breathing, both settings induced a significant increase in minute ventilation (p < 0.01). Both settings were able to reduce the diaphragmatic pressure-time product, but the reduction was significantly greater with PHY (by 64%; p < 0.01) than with U (56%; p < 0.05). Eleven of 23 patients (48%) with U and 7 of 23 patients (30%) with PHY showed ineffective efforts (IE); the prevalence of IE (20 +/- 39% vs 6 +/- 11% of their respiratory rate with U and PHY, respectively) was statistically different (p < 0.05). CONCLUSION In COPD patients with chronic hypercapnia, NPSV is effective in improving arterial blood gases and in unloading inspiratory muscles independent of whether it is set on the basis of patient comfort and improvement in arterial blood gases or tailored to a patient's respiratory muscle effort and mechanics. However, setting of inspiratory assistance and PEEPe by the invasive evaluation of lung mechanics and respiratory muscle function may result in reduction in ineffective inspiratory efforts. These short-term results must be confirmed in the long-term clinical setting.
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Affiliation(s)
- M Vitacca
- Pulmonary Department, Scientific Institute of Gussago, Fondazione Salvatore Maugeri IRCCS, Gussago, Italy
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21
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Tung A. Perioperative Ventilation of the Vascular Surgery Patient. Semin Cardiothorac Vasc Anesth 2000. [DOI: 10.1177/108925320000400408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although cardiovascular disease represents the most com mon comorbidity in patients undergoing vascular surgery, perioperative ventilatory issues can also play a vital role in achieving good outcomes. Postoperative respiratory failure is uncommon after carotid endarterectomy or peripheral revascularization procedures, the risk of pulmonary compli cations following intra-abdominal or intrathoracic vascular surgery is high. In addition to primary lung diseases such as chronic obstructive pulmonary disease, associated organ dysfunction syndromes such as stroke, renal failure, and congestive heart failure can also contribute to respiratory morbidity. An approach to minimizing respiratory complica tions begins with a careful preoperative search for ways to maximize pulmonary function and establishment of targets for postoperative weaning. Intraoperative attention should be paid to intraoperative management of bronchospasm, auto-positive end-expiratory pressure, and acid-base status. Postoperative management should strive for rapid extuba tion, continuation of pharmacologic conditioning programs begun preoperatively, and consideration of the use of post operative regional analgesia for patients with severe lung disease.
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Affiliation(s)
- Avery Tung
- Department of Anesthesia and Critical Care, The University of Chicago, Chicago, IL
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22
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Nucci G, Mergoni M, Bricchi C, Polese G, Cobelli C, Rossi A. On-line monitoring of intrinsic PEEP in ventilator-dependent patients. J Appl Physiol (1985) 2000; 89:985-95. [PMID: 10956342 DOI: 10.1152/jappl.2000.89.3.985] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Measurement of the intrinsic positive end-expiratory pressure (PEEP(i)) is important in planning the management of ventilated patients. Here, a new recursive least squares method for on-line monitoring of PEEP(i) is proposed for mechanically ventilated patients. The procedure is based on the first-order model of respiratory mechanics applied to experimental measurements obtained from eight ventilator-dependent patients ventilated with four different ventilatory modes. The model PEEP(i) (PEEP(i,mod)) was recursively constructed on an inspiration-by-inspiration basis. The results were compared with two well-established techniques to assess PEEP(i): end-expiratory occlusion to measure static PEEP(i) (PEEP(i, st)) and change in airway pressure preceding the onset of inspiratory airflow to measure dynamic PEEP(i) (PEEP(i,dyn)). PEEP(i, mod) was significantly correlated with both PEEP(i,dyn) (r = 0.77) and PEEP(i,st) (r = 0.90). PEEP(i,mod) (5.6 +/- 3.4 cmH(2)O) was systematically >PEEP(i,dyn) and PEEP(i,st) (2.7 +/- 1.9 and 8.1 +/- 5.5 cmH(2)O, respectively), in all the models without external PEEP. Focusing on the five patients with chronic obstructive pulmonary disease, PEEP(i,mod) was significantly correlated with PEEP(i,st) (r = 0.71), whereas PEEP(i,dyn) (r = 0.22) was not. When PEEP was set 5 cmH(2)O above PEEP(i,st), all the methods correctly estimated total PEEP, i.e., 11.8 +/- 5.3, 12.5 +/- 5.0, and 12.0 +/- 4.7 cmH(2)O for PEEP(i,mod), PEEP(i,st), and PEEP(i,dyn), respectively, and were highly correlated (0.97-0.99). We interpreted PEEP(i,mod) as the lower bound of PEEP(i,st) and concluded that our method is suitable for on-line monitoring of PEEP(i) in mechanically ventilated patients.
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Affiliation(s)
- G Nucci
- Dipartimento di Elettronica ed Informatica, University of Padova, 35131 Padova, Italy.
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Issues in Ventilator Weaning. Chest 1999. [DOI: 10.1016/s0012-3692(16)37774-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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