Complex Heart-Lung Ventilator Emergencies in the CICU

This review aims to enhance the comprehension and management of cardiopulmonary interactions in critically ill patients with cardiovascular disease undergoing mechanical ventilation. Highlighting the significance of maintaining a delicate balance, this article emphasizes the crucial role of adjusting ventilation parameters based on both invasive and noninvasive monitoring. It provides recommendations for the induction and liberation from mechanical ventilation. Special attention is given to the identification of auto-PEEP (positive end-expiratory pressure) and other situations that may impact hemodynamics and patients' outcomes.

EMS Treatment Guidelines in Major Traumatic Brain Injury With Positive Pressure Ventilation

Importance

The Excellence in Prehospital Injury Care (EPIC) study demonstrated improved survival in patients with severe traumatic brain injury (TBI) following implementation of the prehospital treatment guidelines. The impact of implementing these guidelines in the subgroup of patients who received positive pressure ventilation (PPV) is unknown.

Objective

To evaluate the association of implementation of prehospital TBI evidence-based guidelines with survival among patients with prehospital PPV.

Design, Setting, and Participants

The EPIC study was a multisystem, intention-to-treat study using a before/after controlled design. Evidence-based guidelines were implemented by emergency medical service agencies across Arizona. This subanalysis was planned a priori and included participants who received prehospital PPV. Outcomes were compared between the preimplementation and postimplementation cohorts using logistic regression, stratified by predetermined TBI severity categories (moderate, severe, or critical). Data were collected from January 2007 to June 2017, and data were analyzed from January to February 2023.

Exposure

Implementation of the evidence-based guidelines for the prehospital care of patient with TBI.

Main Outcomes and Measures

The primary outcome was survival to hospital discharge, and the secondary outcome was survival to admission.

Results

Among the 21 852 participants in the main study, 5022 received prehospital PPV (preimplementation, 3531 participants; postimplementation, 1491 participants). Of 5022 included participants, 3720 (74.1%) were male, and the median (IQR) age was 36 (22-54) years. Across all severities combined, survival to admission improved (adjusted odds ratio [aOR], 1.59; 95% CI, 1.28-1.97), while survival to discharge did not (aOR, 0.94; 95% CI, 0.78-1.13). Within the cohort with severe TBI but not in the moderate or critical subgroups, survival to hospital admission increased (aOR, 6.44; 95% CI, 2.39-22.00), as did survival to discharge (aOR, 3.52; 95% CI, 1.96-6.34).

Conclusions and Relevance

Among patients with severe TBI who received active airway interventions in the field, guideline implementation was independently associated with improved survival to hospital admission and discharge. This was true whether they received basic airway interventions or advanced airways. These findings support the current guideline recommendations for aggressive prevention/correction of hypoxia and hyperventilation in patients with severe TBI, regardless of which airway type is used.

The depth of neuromuscular blockade is not related to chest wall elastance and respiratory mechanics in moderate to severe acute respiratory distress syndrome patients. A prospective cohort study

BACKGROUND

Data concerning the depth of neuromuscular blockade (NMB) required for effective relaxation of the respiratory muscles in ARDS are scarce. We hypothesised that complete versus partial NMB can modify respiratory mechanics.

METHOD

Prospective study to compare the respiratory mechanics of ARDS patients according to the NMB depth. Each patient was analysed at two times: deep NMB (facial train of four count (TOFC) = 0) and intermediate NMB (TOFC >0). The primary endpoint was the comparison of chest wall elastance (ELCW) according to the NMB level.

RESULTS

33 ARDS patients were analysed. There was no statistical difference between the ELCW at TOFC = 0 compared to TOFC >0: 7 cmH2O/l [5.7-9.5] versus 7 cmH2O/l [5.3-10.8] (p = 0.36). The depth of NMB did not modify the expiratory nor inspiratory oesophageal pressure (Pesexp = 8 cmH2O [5-9.5] at TOFC = 0 versus 7 cmH2O [5-10] at TOFC >0; (p = 0.16) and Pesinsp = 10 cmH2O [8.2-13] at TOFC = 0 versus 10 cmH2O [8-13] at TOFC >0; (p = 0.12)).

CONCLUSION

In ARDS, the relaxation of the respiratory muscles seems to be independent of the NMB level.

Newborn resuscitation timelines: Accurately capturing treatment in the delivery room

OBJECTIVES

To evaluate the use of newborn resuscitation timelines to assess the incidence, sequence, timing, duration of and response to resuscitative interventions.

METHODS

A population-based observational study conducted June 2019-November 2021 at Stavanger University Hospital, Norway. Parents consented to participation antenatally. Newborns ≥28 weeks' gestation receiving positive pressure ventilation (PPV) at birth were enrolled. Time of birth was registered. Dry-electrode electrocardiogram was applied as soon as possible after birth and used to measure heart rate continuously during resuscitation. Newborn resuscitation timelines were generated from analysis of video recordings.

RESULTS

Of 7466 newborns ≥28 weeks' gestation, 289 (3.9%) received PPV. Of these, 182 had the resuscitation captured on video, and were included. Two-thirds were apnoeic, and one-third were breathing ineffectively at the commencement of PPV. PPV was started at median (quartiles) 72 (44, 141) seconds after birth and continued for 135 (68, 236) seconds. The ventilation fraction, defined as the proportion of time from first to last inflation during which PPV was provided, was 85%. Interruption in ventilation was most frequently caused by mask repositioning and auscultation. Suctioning was performed in 35% of newborns, in 95% of cases after the initiation of PPV. PPV was commenced within 60 s of birth in 49% of apnoeic and 12% of ineffectively breathing newborns, respectively.

CONCLUSIONS

Newborn resuscitation timelines can graphically present accurate, time-sensitive and complex data from resuscitations synchronised in time. Timelines can be used to enhance understanding of resuscitation events in data-guided quality improvement initiatives.

Providing Positive End-Expiratory Pressure during Neonatal Resuscitation: A Meta-analysis

Our objective was to conduct a systematic review and meta-analysis evaluating the effects of administering positive end-expiratory pressure (PEEP) during neonatal resuscitation at birth. Medline, Web of Science, Scopus, Cochrane Central Register of Controlled Trials, and Clinicaltrials.gov databases were systematically searched from inception to 15 December 2020. Randomized controlled trials and cohort studies were held eligible. Studies were included if they compared the administration of PEEP using either a T-piece resuscitator or a self-inflating bag with a PEEP valve versus resuscitation via a self-inflating bag without a PEEP valve. Data were extracted by two reviewers independently. The credibility of evidence was appraised with the Grading of Recommendations, Assessment, Development, and Evaluations approach. Random-effects models were fitted to provide pooled estimates of risk ratio (RR) and 95% confidence intervals (CIs). Overall, 10 studies were included, comprising 4,268 neonates. This included five randomized controlled trials, one quasi-randomized trial, and four cohort studies. The administration of PEEP was associated with significantly lower rates of mortality till discharge (odds ratio [OR]: 0.60, 95% CI: 0.49-0.74, moderate quality of evidence). The association was significant in preterm (OR: 0.57, 95% CI: 0.46-0.69) but not in term (OR: 1.03, 95% CI: 0.52-2.02) neonates. Low-to-moderate quality evidence suggests that providing PEEP during neonatal resuscitation is associated with lower rates of mortality in preterm neonates. Evidence regarding term neonates is limited and inconclusive. Future research is needed to determine the optimal device and shed more light on the long-term effects of PEEP administration during neonatal resuscitation. This study is registered with PROSPERO with registration number: CRD42020219956. KEY POINTS: · PEEP administration during neonatal resuscitation in the delivery room reduces mortality in preterm.. · Evidence regarding term neonates is limited and inconclusive.. · Future research is needed to determine the optimal device..

Effects of positive end-expiratory pressure on regional cerebral oxygen saturation in elderly patients undergoing thoracic surgery during one-lung ventilation: a randomized crossover-controlled trial

BACKGROUND

A significant reduction in regional cerebral oxygen saturation (rSO2) is commonly observed during one-lung ventilation (OLV), while positive end-expiratory pressure (PEEP) can improve oxygenation. We compared the effects of three different PEEP levels on rSO2, pulmonary oxygenation, and hemodynamics during OLV.

METHODS

Forty-three elderly patients who underwent thoracoscopic lobectomy were randomly assigned to one of six PEEP combinations which used a crossover design of 3 levels of PEEP-0 cmH2O, 5 cmH2O, and 10 cmH2O. The primary endpoint was rSO2 in patients receiving OLV 20 min after adjusting the PEEP. The secondary outcomes included hemodynamic and respiratory variables.

RESULTS

After exclusion, thirty-six patients (36.11% female; age range: 60-76 year) were assigned to six groups (n = 6 in each group). The rSO2 was highest at OLV(0) than at OLV(10) (difference, 2.889%; [95% CI, 0.573 to 5.204%]; p = 0.008). Arterial oxygen partial pressure (PaO2) was lowest at OLV(0) compared with OLV(5) (difference, -62.639 mmHg; [95% CI, -106.170 to -19.108 mmHg]; p = 0.005) or OLV(10) (difference, -73.389 mmHg; [95% CI, -117.852 to -28.925 mmHg]; p = 0.001), while peak airway pressure (Ppeak) was lower at OLV(0) (difference, -4.222 mmHg; [95% CI, -5.140 to -3.304 mmHg]; p < 0.001) and OLV(5) (difference, -3.139 mmHg; [95% CI, -4.110 to -2.167 mmHg]; p < 0.001) than at OLV(10).

CONCLUSIONS

PEEP with 10 cmH2O makes rSO2 decrease compared with 0 cmH2O. Applying PEEP with 5 cmH2O during OLV in elderly patients can improve oxygenation and maintain high rSO2 levels, without significantly increasing peak airway pressure compared to not using PEEP.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200060112 on 19 May 2022.

Positive end-expiratory pressure in the pediatric intensive care unit

Application of positive end-expiratory pressure (PEEP) targeted towards improving oxygenation is one of the components of the ventilatory management of pediatric acute respiratory distress syndrome (PARDS). Low end-expiratory airway pressures cause repetitive opening and closure of unstable alveoli, leading to surfactant dysfunction and parenchymal shear injury. Consequently, there is less lung volume available for tidal ventilation when there are atelectatic lung regions. This will increase lung strain in aerated lung areas to which the tidal volume is preferentially distributed. Pediatric critical care practitioners tend to use low levels of PEEP and inherently accept higher FiO2, but these practices may negatively affect patient outcome. The Pediatric Acute Lung Injury Consensus Conference (PALICC) suggests that PEEP should be titrated to oxygenation/oxygen delivery, hemodynamics, and compliance measured under static conditions as compared to other clinical parameters or any of these parameters in isolation in patients with PARDS, while limiting plateau pressure and/or driving pressure limits.

Calculating intrinsic positive end-expiratory pressure from end-expiratory flow in mechanically ventilated children-A study in physical models of the pediatric respiratory system

RATIONALE

The high resistance of pediatric endotracheal tubes (ETTs) exposes mechanically ventilated children to a particular risk of developing intrinsic positive end-expiratory pressure (iPEEP). To date, determining iPEEP at the bedside requires the execution of special maneuvers, interruption of ventilation, or additional invasive measurements. Outside such interventions, iPEEP may be unrecognized.

OBJECTIVE

To develop a new approach for continuous calculation of iPEEP based on routinely measured end-expiratory flow and ETT resistance.

METHODS

First, the resistance of pediatric ETTs with inner diameter from 2.0 to 4.5 mm were empirically determined. Second, during simulated ventilation, iPEEP was either calculated from the measured end-expiratory flow and ETT's resistance (iPEEPcalc ) or determined with a hold-maneuver available at the ventilator (iPEEPhold ). Both estimates were compared with the end-expiratory pressure measured at the ETT's tip (iPEEPdirect ) by means of absolute deviations.

RESULTS

End-expiratory flow and iPEEP increased with decreasing ETT inner diameter and with higher respiratory rates. iPEEPcalc and iPEEPhold were comparable and indicated good correspondence with iPEEPdirect . The largest absolute mean deviation was 1.0 cm H2 O for iPEEPcalc and 1.1 cm H2 O for iPEEPhold .

CONCLUSION

We conclude that iPEEP can be determined from routinely measured variables and predetermined ETT resistance, which has to be confirmed in the clinical settings. As long as this algorithm is not available in pediatric ICU ventilators, nomograms are provided for estimating the prevailing iPEEP from end-expiratory flow.

Noninvasive respiratory support preventing reintubation after pediatric cardiac surgery-A systematic review

OBJECTIVE

To analyze the optimal postextubation respiratory support in pediatric cardiac surgery patients.

DESIGN

Systematic review of randomized controlled trials.

SETTING

Pediatric or neonatal intensive care units.

PARTICIPANTS

All aged children (<16 years) having cardiac surgery and postoperative invasive ventilation.

INTERVENTION

Noninvasive respiratory support, including high flow nasal cannula (HFNC), conventional oxygen therapy (COT), noninvasive positive pressure ventilation (NIPPV), continuous positive pressure (CPAP), and noninvasive high-frequency oscillatory ventilation (NHFOV).

MEASUREMENT AND MAIN RESULTS

Studies were not pooled for statistical synthesis due to the limited number and quality of the included studies. Risk ratios with 95% confidence intervals were calculated for individual studies. A total of 167 studies were screened and six were included. The risk of bias was low in one, high in one, and had some concerns in four of the studies. Extubation failure (defined as reintubation) was the main outcome of interest. Risk ratio for reintubation was 0.10 (CI 0.02-0.40) and 1.07 (CI 0.16-7.26) in HFNC versus COT, 0.49 (CI 0.05-5.28) in HFNC versus NIPPV, 0.40 (CI 0.08-1.94) in HFNOV versus CPAP, 0.75 (CI 0.26-2.18) in HFNOV versus NIPPV, and 1.37 (CI 0.33-5.73) in CPAP versus NIPPV. Treatment durations did not differ between the groups.

CONCLUSION

We did not find clear evidence of a difference in reintubation rates and other clinical outcomes between different noninvasive ventilation strategies. Evidence certainty was assessed to be very low due to the risk of bias, the small number of included studies, and high imprecision. Future quality studies are needed to determine the optimal postextubation support in pediatric cardiac surgery patients.

Capnodynamic end-expiratory lung volume assessment in anesthetized healthy children

BACKGROUND

Capnodynamic lung function monitoring generates variables that may be useful for pediatric perioperative ventilation.

AIMS

Establish normal values for end-expiratory lung volume CO2 in healthy children undergoing anesthesia and to compare these values to previously published values obtained with alternative end-expiratory lung volume methods. The secondary aim was to investigate the ability of end-expiratory lung volume CO2 to react to positive end-expiratory pressure-induced changes in end-expiratory lung volume. In addition, normal values for associated volumetric capnography lung function variables were examined.

METHODS

Fifteen pediatric patients with healthy lungs (median age 8 months, range 1-36 months) undergoing general anesthesia were examined before start of surgery. Tested variables were recorded at baseline positive end-expiratory pressure 3 cmH2 O, 1 and 3 min after positive end-expiratory pressure 10 cmH2 O and 3 min after returning to baseline positive end-expiratory pressure 3 cmH2 O.

RESULTS

Baseline end-expiratory lung volume CO2 was 32 mL kg-1 (95% CI 29-34 mL kg-1 ) which increased to 39 mL kg-1 (95% CI 35-43 mL kg-1 , p < .0001) and 37 mL kg-1 (95% CI 34-41 mL kg-1 , p = .0003) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively. End-expiratory lung volume CO2 returned to baseline, 33 mL kg-1 (95% CI 29-37 mL kg-1 , p = .72) 3 min after re-establishing positive end-expiratory pressure 3 cmH2 O. Airway dead space increased from 1.1 mL kg-1 (95% CI 0.9-1.4 mL kg-1 ) to 1.4 (95% CI 1.1-1.8 mL kg-1 , p = .003) and 1.5 (95% CI 1.1-1.8 mL kg-1 , p < .0001) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively, and 1.2 mL kg-1 (95% CI 0.9-1.4 mL kg-1 , p = .08) after 3 min of positive end-expiratory pressure 3 cmH2 O. Additional volumetric capnography and lung function variables showed no major changes in response to positive end-expiratory pressure variations.

CONCLUSIONS

Capnodynamic noninvasive and continuous end-expiratory lung volume CO2 values assessed during anesthesia in children were in close agreement with previously reported end-expiratory lung volume values generated by alternative methods. Furthermore, positive end-expiratory pressure changes resulted in physiologically expected end-expiratory lung volume CO2 responses in a timely manner, suggesting that it can be used to trend end-expiratory lung volume changes during anesthesia.

Positive end-expiratory pressure in chronic care of children with obstructive sleep apnoea

Positive end-expiratory pressure (PEEP) consists of the delivery of a constant positive pressure in the airways by means of a noninvasive interface aiming to maintain airway patency throughout the entire respiratory cycle. PEEP is increasingly used in the chronic care of children with anatomical or functional abnormalities of the upper airways to correct severe persistent obstructive sleep apnea despite optimal management which commonly includes adenotonsillectomy in young children. PEEP may be used at any age, due to improvements in equipment and interfaces. Criteria for CPAP/NIV initiation, optimal setting, follow-up and monitoring, as well as weaning criteria have been established by international experts, but validated criteria are lacking. As chronic PEEP is a highly specialised treatment, patients should be managed by an expert pediatric multidisciplinary team.

Predictive performance of the variation rate of the driving pressure on the outcome of invasive mechanical ventilation in patients with acute respiratory distress syndrome

PURPOSE

To assess the value of the driving pressure variation rate (ΔP%) in predicting the outcome of weaning from invasive mechanical ventilation in patients with acute respiratory distress syndrome.

METHODS

In this case-control study, a total of 35 patients with moderate-severe acute respiratory distress syndrome were admitted to the intensive care unit between January 2022 and December 2022 and received invasive mechanical ventilation for at least 48 h were enrolled. Patients were divided into successful weaning group and failed weaning group depending on whether they could be removed from ventilator support within 14 days. Outcome measures including driving pressure, PaO2:FiO2, and positive end-expiratory pressure, etc. were assessed every 24 h from day 0 to day 14 until successful weaning was achieved. The measurement data of non-normal distribution were presented as median (Q1, Q3), and the differences between groups were compared by Wilcoxon rank sum test. And categorical data use the Chi-square test or Fisher's exact test to compare. The predictive value of ΔP% in predicting the outcome of weaning from the ventilator was analyzed using receiver operating characteristic curves.

RESULTS

Of the total 35 patients included in the study, 17 were successful vs. 18 failed in weaning from a ventilator after 14 days of mechanical ventilation. The cut-off values of the median ΔP% measured by Operator 1 vs. Operator 2 in the first 4 days were ≥ 4.17% and 4.55%, respectively (p < 0.001), with the area under curve of 0.804 (sensitivity of 88.2%, specificity of 64.7%) and 0.770 (sensitivity of 88.2%, specificity of 64.7%), respectively. There was a significant difference in mechanical ventilation duration between the successful weaning group and the failure weaning group (8 (6, 13) vs. 12 (7.5, 17.3), p = 0.043). The incidence of ventilator-associated pneumonia in the successful weaning group was significantly lower than in the failed weaning group (0.2‰ vs. 2.3‰, p = 0.001). There was a significant difference noted between these 2 groups in the 28-day mortality (11.8% vs. 66.7%, p = 0.003).

CONCLUSION

The median ΔP% in the first 4 days of mechanical ventilation showed good predictive performance in predicting the outcome of weaning from mechanical ventilation within 14 days. Further study is needed to confirm this finding.

Early Pulmonary Hypertension in Preterm Infants

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Volume-targeted mask ventilation during simulated neonatal resuscitation

OBJECTIVE

Mask positive pressure ventilation (PPV) in the delivery room is routinely delivered with set peak inflation pressures. To aid mask PPV, stand-alone respiratory function monitors (RFMs) have been used in the delivery room, while ventilator-based, volume-targeted ventilation (VTV) is routinely used in the neonatal intensive care unit (NICU).

DESIGN

This is a prospective, randomised, crossover simulation study. Participants were briefly trained to use a neonatal ventilator for volume-targeted mask ventilation (VTV-PPV), then performed mask ventilation on a manikin in a randomised order using VTV-PPV, T-piece PPV or T-piece PPV with RFM visible.

SETTING

In situ in a neonatal resuscitation room within a level 3 NICU.

PARTICIPANTS

Healthcare professionals (HCPs) trained in neonatal resuscitation with experience as team leaders.

INTERVENTIONS

Semiautomated, ventilator-based VTV-PPV using two-hand hold versus manual PPV via a T-piece device (T-piece, RFM masked) versus manual PPV with RFM visible using one-hand hold.

MAIN OUTCOME MEASURES

Respiratory characteristics including % mask leak, tidal volume (VT) and peak inflation pressure (PIP).

RESULTS

Thirty-two HCPs (23 (72%) female and 9 (28%) male) participated. The median mask leak was significantly lower with 'VTV-PPV' (11%, IQR 0%-14%) compared with both 'T-piece, RFM visible' (82%, IQR 30%-91%) and 'T-piece, RFM masked' (81%, IQR 47%-91%) (p<0.0001). The median delivered VT was 4.1 mL/kg (IQR 3.9-4.4) with VTV-PPV compared with 2.1 mL/kg (IQR 1.2-9) with T-piece, RFM visible and 1.8 mL/kg (IQR 1.1-5.8) with T-piece, RFM masked (p=0.0496). PIP was also significantly lower with VTV-PPV.

CONCLUSION

During neonatal simulation, VTV-PPV reduced mask leak and allowed for consistent VT delivery compared with T-piece with and without RFM guidance.

Effects of weights applied to the apex of a bag-valve-mask and pinch strength on tidal volume: a prospective simulation study

A bag-valve-mask (BVM) is a first aid tool that can easily and quickly provide positive-pressure ventilation in patients with breathing difficulties. The most important aspect of BVM bagging is how closely the mask adheres to the patient's face when the E-C technique is used. In particular, the greater the adhesion force at the apex of the mask, the greater the tidal volume. The purpose of this study was to investigate the effect of various weights applied to the mask's apex and the pinch strength needed to perform the E-C technique, on tidal volume. In this prospective simulation study, quasi-experimental and equivalent time-series designs were used. A total of 72 undergraduate paramedic student from three universities were recruited using convenience sampling. The tidal volumes according to the weights (0 g, 100 g, 200 g, 300 g) applied to the apical area of the mask, handgrip strength, and pinch strength (tip pinch strength, key pinch strength, and tripod pinch strength) were measured. A linear mixed model analysis was performed. Linear mixed model analyses showed that tidal volume was significantly higher at 200 g (B = 43.38, p = 0.022) and 300 g (B = 38.74, p = 0.017) than at 0 g. Tripod pinch strength (B = 12.88, p = 0.007) had a significant effect on mask adhesion for effective BVM ventilation. Adding weight to the apical area of the mask can help maintain the E-C technique and enable effective ventilation. Future studies are required to develop specific strategies to improve the ventilation skills, which can be an important first-aid activity.

Comparison of pressure controlled, volume controlled, and volume guaranteed pressure controlled modes in prone position in patients operated for lumbar disc herniation: A randomized trial

BACKGROUND

To compare pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), and pressure-controlled ventilation-volume guaranteed (PCV-VG) modes in patients undergoing spinal surgery in the prone position under general anesthesia.

METHODS

The study included 78 patients aged 20 to 80 years, American Society of Anesthesiologists 1-2, scheduled for lumbar spinal surgery. Patients included in the study were randomly divided into 3 groups Group-VCV; Group-PCV; Group-PCV-VG. Standard anesthesia protocol was applied. In addition to routine monitoring, train of four and BIS monitoring were performed. All ventilation modes were set with a target tidal volume of 6 to 8 mL/kg, FiO2: 0.40-0.45 and a respiratory rate of normocarbia. Positive end-expiratory pressure: 5 cm H2O, inspiration/expiration ratio = 1:2, and the maximum airway pressure:40 cm H2O. Hemodynamic, respiratory variables and arterial blood gases was measured, 15 minutes after induction of anesthesia in the supine position (T1), after prone position 15 minutes (T2), 30 minutes (T3), 45 minutes (T4), 60 minutes (T5), 75 minutes (T6), 90 minutes (T7).

RESULTS

There was no significant difference between the groups in patient characteristics. SAP, DAP, mean arterial pressure, and heart rate decreased after being placed in the prone position in all groups. Hemodynamic variables did not differ significantly between the groups. partial arterial oxygen pressure and arterial oxygen saturation levels in blood gas were found to be significantly higher in Group-PCV-VG compared to Group-PCV and Group-VCV in both the supine and prone positions. Ppeak and plateau airway pressure (Pplato) values increased and dynamic lung compliance (Cdyn) values decreased after placing the patients in the prone position in all groups. Lower Ppeak and Pplato values and higher Cdyn values were observed in both the supine and prone positions in the Group-PCV-VG group compared to the Group-PCV and Group-VCV groups.

CONCLUSION

PCV-VG provides lower Ppeak and Pplato values, as well as better Cdyn, oxygenation values compared to PCV and VCV. So that PCV-VG may be an effective alternative mode of mechanical ventilation for patients in the prone position during lumbar spine surgery.

Setting positive end-expiratory pressure: role in diaphragm-protective ventilation

PURPOSE OF REVIEW

With mechanical ventilation, positive end-expiratory pressure (PEEP) is applied to improve oxygenation and lung homogeneity. However, PEEP setting has been hypothesized to contribute to critical illness associated diaphragm dysfunction via several mechanisms. Here, we discuss the impact of PEEP on diaphragm function, activity and geometry.

RECENT FINDINGS

PEEP affects diaphragm geometry: it induces a caudal movement of the diaphragm dome and shortening of the zone of apposition. This results in reduced diaphragm neuromechanical efficiency. After prolonged PEEP application, the zone of apposition adapts by reducing muscle fiber length, so-called longitudinal muscle atrophy. When PEEP is withdrawn, for instance during a spontaneous breathing trial, the shortened diaphragm muscle fibers may over-stretch which may lead to (additional) diaphragm myotrauma. Furthermore, PEEP may either increase or decrease respiratory drive and resulting respiratory effort, probably depending on lung recruitability. Finally, the level of PEEP can also influence diaphragm activity in the expiratory phase, which may be an additional mechanism for diaphragm myotrauma.

SUMMARY

Setting PEEP could play an important role in both lung and diaphragm protective ventilation. Both high and low PEEP levels could potentially introduce or exacerbate diaphragm myotrauma. Today, the impact of PEEP setting on diaphragm structure and function is in its infancy, and clinical implications are largely unknown.

Ventilation during extracorporeal gas exchange in acute respiratory distress syndrome

PURPOSE OF REVIEW

Accumulating evidence ascribes the benefit of extracorporeal gas exchange, at least in most severe cases, to the provision of a lung healing environment through the mitigation of ventilator-induced lung injury (VILI) risk. In spite of pretty homogeneous criteria for extracorporeal gas exchange application (according to the degree of hypoxemia/hypercapnia), ventilatory management during extracorporeal membrane oxygenation (ECMO)/carbon dioxide removal (ECCO 2 R) varies across centers. Here we summarize the recent evidence regarding the management of mechanical ventilation during extracorporeal gas exchange for respiratory support.

RECENT FINDINGS

At present, the most common approach to protect the native lung against VILI following ECMO initiation involves lowering tidal volume and driving pressure, making modest reductions in respiratory rate, while typically maintaining positive end-expiratory pressure levels unchanged.Regarding ECCO 2 R treatment, higher efficiency devices are required in order to reduce significantly respiratory rate and/or tidal volume.

SUMMARY

The best compromise between reduction of native lung ventilatory load, extracorporeal gas exchange efficiency, and strategies to preserve lung aeration deserves further investigation.

Setting positive end-expiratory pressure: lung and diaphragm ultrasound

PURPOSE OF REVIEW

The purpose of this review is to summarize the role of lung ultrasound and diaphragm ultrasound in guiding ventilator settings with an emphasis on positive end-expiratory pressure (PEEP). Recent advances for using ultrasound to assess the effects of PEEP on the lungs and diaphragm are discussed.

RECENT FINDINGS

Lung ultrasound can accurately diagnose the cause of acute respiratory failure, including acute respiratory distress syndrome and can identify focal and nonfocal lung morphology in these patients. This is essential in determining optimal ventilator strategy and PEEP level. Assessment of the effect of PEEP on lung recruitment using lung ultrasound is promising, especially in the perioperative setting. Diaphragm ultrasound can monitor the effects of PEEP on the diaphragm, but this needs further validation. In patients with an acute exacerbation of chronic obstructive pulmonary disease, diaphragm ultrasound can be used to predict noninvasive ventilation failure. Lung and diaphragm ultrasound can be used to predict weaning outcome and accurately diagnose the cause of weaning failure.

SUMMARY

Lung and diaphragm ultrasound are useful for diagnosing the cause of respiratory failure and subsequently setting the ventilator including PEEP. Effects of PEEP on lung and diaphragm can be monitored using ultrasound.

Respiratory mechanics and mechanical power during low vs. high positive end-expiratory pressure in obese surgical patients - A sub-study of the PROBESE randomized controlled trial

STUDY OBJECTIVE

We aimed to characterize intra-operative mechanical ventilation with low or high positive end-expiratory pressure (PEEP) and recruitment manoeuvres (RM) regarding intra-tidal recruitment/derecruitment and overdistension using non-linear respiratory mechanics, and mechanical power in obese surgical patients enrolled in the PROBESE trial.

DESIGN

Prospective, two-centre substudy of the international, multicentre, two-arm, randomized-controlled PROBESE trial.

SETTING

Operating rooms of two European University Hospitals.

PATIENTS

Forty-eight adult obese patients undergoing abdominal surgery.

INTERVENTIONS

Intra-operative protective ventilation with either PEEP of 12 cmH2O and repeated RM (HighPEEP+RM) or 4 cmH2O without RM (LowPEEP).

MEASUREMENTS

The index of intra-tidal recruitment/de-recruitment and overdistension (%E2) as well as airway pressure, tidal volume (VT), respiratory rate (RR), resistance, elastance, and mechanical power (MP) were calculated from respiratory signals recorded after anesthesia induction, 1 h thereafter, and end of surgery (EOS).

MAIN RESULTS

Twenty-four patients were analyzed in each group. PEEP was higher (mean ± SD, 11.7 ± 0.4 vs. 3.7 ± 0.6 cmH2O, P < 0.001) and driving pressure lower (12.8 ± 3.5 vs. 21.7 ± 6.8 cmH2O, P < 0.001) during HighPEEP+RM than LowPEEP, while VT and RR did not differ significantly (7.3 ± 0.6 vs. 7.4 ± 0.8 ml∙kg-1, P = 0.835; and 14.6 ± 2.5 vs. 15.7 ± 2.0 min-1, P = 0.150, respectively). %E2 was higher in HighPEEP+RM than in LowPEEP following induction (-3.1 ± 7.2 vs. -12.4 ± 10.2%; P < 0.001) and subsequent timepoints. Total resistance and elastance (13.3 ± 3.8 vs. 17.7 ± 6.8 cmH2O∙l∙s-2, P = 0.009; and 15.7 ± 5.5 vs. 28.5 ± 8.4 cmH2O∙l, P < 0.001, respectively) were lower during HighPEEP+RM than LowPEEP. Additionally, MP was lower in HighPEEP+RM than LowPEEP group (5.0 ± 2.2 vs. 10.4 ± 4.7 J∙min-1, P < 0.001).

CONCLUSIONS

In this sub-cohort of PROBESE, intra-operative ventilation with high PEEP and RM reduced intra-tidal recruitment/de-recruitment as well as driving pressure, elastance, resistance, and mechanical power, as compared with low PEEP.

TRIAL REGISTRATION

The PROBESE study was registered at www.

CLINICALTRIALS

gov, identifier: NCT02148692 (submission for registration on May 23, 2014).

[Clinical study of optimal positive end-expiratory pressure titration guided by lung stretch index in patients with acute respiratory distress syndrome]

OBJECTIVE

To investigate the clinical practicability of positive end-expiratory pressure (PEEP) titrated by lung stretch index (SI) in patients with acute respiratory distress syndrome (ARDS).

METHODS

A parallel randomized controlled trial was conducted. Patients with moderate to severe ARDS who required mechanical ventilation admitted to the department of critical care medicine of General Hospital of the Yangtze River Shipping from August 2022 to February 2023 were enrolled. They were randomly divide into SI guided PEEP titration group (SI group) and pressure-volume curve (P-V curve) inspiratory low inflection point (LIP) guided PEEP titration group (LIP group). All patients were ventilated in a supine position after admission, with the head of the bed raised by 30 degree angle. The primary disease was actively treated, prone position ventilation for 12 h/d, and lung protective ventilation strategies such as controlled lung expansion were used for lung recruitment. On this basis, mechanical ventilation parameters were titrated with SI in the SI group; the LIP group titrated mechanical ventilation parameters with P-V curve inspiratory LIP+2 cmH2O (1 cmH2O≈0.098 kPa). The oxygenation index (PaO2/FiO2), and respiratory mechanics indicators such as lung dynamic compliance (Cdyn), peak airway pressure (Pip) were monitored before recruitment maneuver and after 1, 3, and 5 days of treatment. The therapeutic effect of the two groups was compared.

RESULTS

There were 41 patients in the SI group and 40 patients in the LIP group. There was no significant difference in general information such as gender, age, and disease type between the two groups. The mechanical ventilation time and the length of intensive care unit (ICU) stay in the SI group were significantly shorter than those in the LIP group (days: 9.47±3.36 vs. 14.68±5.52, 22.27±4.68 vs. 27.57±9.52, both P < 0.05). Although the 28-day mortality of the SI group was lower than that of the LIP group, the difference was not statistically significant [19.5% (8/41) vs. 35.0% (14/40), P > 0.05]. On the fifth day, the PaO2/FiO2 was higher in SI group [mmHg (1 mmHg≈0.133 kPa): 225.57±47.85 vs. 198.32±31.59, P < 0.05], the Cdyn was higher in SI group (mL/cmH2O: 47.39±6.71 vs. 35.88±5.35, P < 0.01), the Pip was lower in SI group (mmHg: 35.85±5.77 vs. 43.87±6.68, P < 0.05). The Kaplan-Meier survival curve showed no statistically significant difference in the 28 days cumulative survival rate between the two groups (Log-Rank: χ 2 = 2.348, P = 0.125).

CONCLUSIONS

The application of SI titration with PEEP in the treatment of ARDS patients may improve their prognosis.

Increasing Levels of Positive End-expiratory Pressure Cause Stepwise Biventricular Stroke Work Reduction in a Porcine Model

BACKGROUND

Positive end-expiratory pressure (PEEP) is commonly applied to avoid atelectasis and improve oxygenation in patients during general anesthesia but affects cardiac pressures, volumes, and loading conditions through cardiorespiratory interactions. PEEP may therefore alter stroke work, which is the area enclosed by the pressure-volume loop and corresponds to the external work performed by the ventricles to eject blood. The low-pressure right ventricle may be even more susceptible to PEEP than the left ventricle. The authors hypothesized that increasing levels of PEEP would reduce stroke work in both ventricles.

METHODS

This was a prospective, observational, experimental study. Six healthy female pigs of approximately 60 kg were used. PEEP was stepwise increased from 0 to 5, 7, 9, 11, 13, 15, 17, and 20 cm H2O to cover the clinical spectrum of PEEP. Simultaneous, biventricular invasive pressure-volume loops, invasive blood pressures, and ventilator data were recorded.

RESULTS

Increasing PEEP resulted in stepwise reductions in left (5,740 ± 973 vs. 2,303 ± 1,154 mmHg · ml; P < 0.001) and right (2,064 ± 769 vs. 468 ± 133 mmHg · ml; P < 0.001) ventricular stroke work. The relative stroke work reduction was similar between the two ventricles. Left ventricular ejection fraction, afterload, and coupling were preserved. On the contrary, PEEP increased right ventricular afterload and caused right ventriculo-arterial uncoupling (0.74 ± 0.30 vs. 0.19 ± 0.13; P = 0.01) with right ventricular ejection fraction reduction (64 ± 8% vs. 37 ± 7%, P < 0.001).

CONCLUSIONS

A stepwise increase in PEEP caused stepwise reduction in biventricular stroke work. However, there are important interventricular differences in response to increased PEEP levels. PEEP increased right ventricular afterload leading to uncoupling and right ventricular ejection fraction decline. These findings may support clinical decision-making to further optimize PEEP as a means to balance between improving lung ventilation and preserving right ventricular function.

EDITOR’S PERSPECTIVE

Setting positive end-expiratory pressure in the severely obstructive patient

PURPOSE OF REVIEW

The response to positive end-expiratory pressure (PEEP) in patients with chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation depends on the underlying pathophysiology. This review focuses on the pathophysiology of COPD, especially intrinsic PEEP (PEEPi) and its consequences, and the benefits of applying external PEEP during assisted ventilation when PEEPi is present.

RECENT FINDINGS

The presence of expiratory airflow limitation and increased airway resistance promotes the development of dynamic hyperinflation in patients with COPD during acute respiratory failure. Dynamic hyperinflation and the associated development of PEEPi increases work of breathing and contributes to ineffective triggering of the ventilator. In the presence of airflow limitation, application of external PEEP during patient-triggered ventilation has been shown to reduce inspiratory effort, facilitate ventilatory triggering and enhance patient-ventilator interaction. To minimize the risk of hyperinflation, it is advisable to limit the level of external PEEP during assisted ventilation after optimization of ventilator settings to about 70% of the level of PEEPi (measured during passive ventilation).

SUMMARY

In patients with COPD and dynamic hyperinflation receiving assisted mechanical ventilation, the application of low levels of external PEEP can minimize work of breathing, facilitate ventilator triggering and improve patient-ventilator interaction.

Effect of paratracheal pressure on the effectiveness of mask ventilation in obese anesthetized patients: a randomized, cross-over study

Paratracheal pressure has been recently suggested to compress and occlude the upper esophagus at the lower left paratracheal region to prevent gastric regurgitation alternative to cricoid pressure. It also prevents gastric insufflation. The aim of this randomized cross-over study was to investigate the effectiveness of paratracheal pressure on mask ventilation in obese anesthetized paralyzed patients. After the induction of anesthesia, two-handed mask ventilation was initiated in a volume-controlled mode with a tidal volume of 8 mL kg‒1 based on ideal body weight (IBW), a respiratory rate of 12 breaths min- 1, and positive end-expiratory pressure of 10 cmH2O. Expiratory tidal volume and peak inspiratory pressure were recorded alternately with or without the application of 30 Newtons (approximately 3.06 kg) paratracheal pressure during a total of 16 successive breaths over 80 s. Association of patient characteristics with the effectiveness of paratracheal pressure on mask ventilation, defined as the difference in expiratory tidal volume between the presence or absence of paratracheal pressure were evaluated. In 48 obese anesthetized paralyzed patients, expiratory tidal volume was significantly higher with the application of paratracheal pressure than without paratracheal pressure [496.8 (74.1) mL kg- 1 of IBW vs. 403.8 (58.4) mL kg- 1 of IBW, respectively; P < 0.001]. Peak inspiratory pressure was also significantly higher with the application of paratracheal pressure compared to that with no paratracheal pressure [21.4 (1.2) cmH2O vs. 18.9 (1.6) cmH2O, respectively; P < 0.001]. No significant association was observed between patient characteristics and the effectiveness of paratracheal pressure on mask ventilation. Hypoxemia did not occur in any of the patients during mask ventilation with or without paratracheal pressure. The application of paratracheal pressure significantly increased both the expiratory tidal volume and peak inspiratory pressure during face-mask ventilation with a volume-controlled mode in obese anesthetized paralyzed patients. Gastric insufflation was not evaluated in this study during mask ventilation with or without paratracheal pressure.

Effects of different positive end-expiratory pressure titration strategies on mechanical power during ultraprotective ventilation in ARDS patients treated with veno-venous extracorporeal membrane oxygenation: A prospective interventional study

PURPOSE

Ultraprotective ventilation in acute respiratory distress syndrome (ARDS) patients with veno-venous extracorporeal membrane oxygenation (VV ECMO) reduces mechanical power (MP) through changes in positive end-expiratory pressure (PEEP); however, the optimal approach to titrate PEEP is unknown. This study assesses the effects of three PEEP titration strategies on MP, hemodynamic parameters, and oxygen delivery in twenty ARDS patients with VV ECMO.

MATERIAL AND METHODS

PEEP was titrated according to: (A) a PEEP of 10 cmH2O representing the lowest recommendation by the Extracorporeal Life Support Organization (PEEPELSO), (B) the highest static compliance of the respiratory system (PEEPCstat,RS), and (C) a target end-expiratory transpulmonary pressure of 0 cmH2O (PEEPPtpexp).

RESULTS

PEEPELSO was lower compared to PEEPCstat,RS and PEEPPtpexp (10.0 ± 0.0 vs. 16.2 ± 4.7 cmH2O and 17.3 ± 4.0 cmH2O, p < 0.001 each, respectively). PEEPELSO reduced MP compared to PEEPCstat,RS and PEEPPtpexp (5.3 ± 1.3 vs. 6.8 ± 2.0 and 6.9 ± 2.3 J/min, p < 0.001 each, respectively). PEEPELSO resulted in less lung stress compared to PEEPCstat,RS (p = 0.011) and PEEPPtpexp (p < 0.001) and increased cardiac output and oxygen delivery (p < 0.001 each).

CONCLUSIONS

An empirical PEEP of 10 cmH2O minimized MP, provided favorable hemodynamics, and increased oxygen delivery in ARDS patients treated with VV ECMO.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00013967). Registered 02/09/2018https://drks.de/search/en/trial/DRKS00013967.

Mechanical ventilation practices in Asian intensive care units: A multicenter cross-sectional study

PURPOSE

This study investigated current practices of mechanical ventilation in Asian intensive care units, focusing on tidal volume, plateau pressure, and positive end-expiratory pressure (PEEP).

MATERIALS AND METHODS

In this multicenter cross-sectional study, data on mechanical ventilation and clinical outcomes were collected. Predictors of mortality were analyzed by univariate and multivariable logistic regression. A scoring system was generated to predict 28-day mortality.

RESULTS

A total of 1408 patients were enrolled. In 138 patients with acute respiratory distress syndrome (ARDS), 65.9% were on a tidal volume ≤ 8 ml/kg predicted body weight (PBW), and 71.3% were on sufficient PEEP. In 1270 patients without ARDS, 88.8% were on a tidal volume ≤ 10 ml/kg PBW. A plateau pressure < 30 cmH2O was measured in 92.2% of patients. Mortality rates increased from 13% to 74% as the generated predictive score increased from 5 to ≥8.5. Income classification, age, SOFA score, PaO2/FiO2 ratio, plateau pressure, number of vasopressors, and steroid use were associated with mortality.

CONCLUSIONS

In Asia, low tidal volume ventilation and sufficient PEEP were underused in patients with ARDS. The majority of patients without ARDS were on intermediate tidal volumes. Country income, age, and severity of illness were associated with mortality.

Setting positive end-expiratory pressure: the use of esophageal pressure measurements

PURPOSE OF REVIEW

To summarize the key concepts, physiological rationale and clinical evidence for titrating positive end-expiratory pressure (PEEP) using transpulmonary pressure ( PL ) derived from esophageal manometry, and describe considerations to facilitate bedside implementation.

RECENT FINDINGS

The goal of an esophageal pressure-based PEEP setting is to have sufficient PL at end-expiration to keep (part of) the lung open at the end of expiration. Although randomized studies (EPVent-1 and EPVent-2) have not yet proven a clinical benefit of this approach, a recent posthoc analysis of EPVent-2 revealed a potential benefit in patients with lower APACHE II score and when PEEP setting resulted in end-expiratory PL values close to 0 ± 2 cmH 2 O instead of higher or more negative values. Technological advances have made esophageal pressure monitoring easier to implement at the bedside, but challenges regarding obtaining reliable measurements should be acknowledged.

SUMMARY

Esophageal pressure monitoring has the potential to individualize the PEEP settings. Future studies are needed to evaluate the clinical benefit of such approach.

Impact of mechanical power and positive end expiratory pressure on central vs. mixed oxygen and carbon dioxide related variables in a population of female piglets

INTRODUCTION

The use of the pulmonary artery catheter has decreased overtime; central venous blood gases are generally used in place of mixed venous samples. We want to evaluate the accuracy of oxygen and carbon dioxide related parameters from a central versus a mixed venous sample, and whether this difference is influenced by mechanical ventilation.

MATERIALS AND METHODS

We analyzed 78 healthy female piglets ventilated with different mechanical power.

RESULTS

There was a significant difference in oxygen-derived parameters between samples taken from the central venous and mixed venous blood (Sv ¯ $$ \overline{v} $$ O2 = 74.6%, ScvO2 = 83%, p < 0.0001). Conversely, CO2-related parameters were similar, with strong correlation. Ventilation with higher mechanical power and PEEP increased the difference between oxygen saturations, (Δ[ScvO2-Sv ¯ $$ \overline{v} $$ O2 ] = 7.22% vs. 10.0% respectively in the low and high MP groups, p = 0.020); carbon dioxide-related parameters remained unchanged (p = 0.344).

CONCLUSIONS

The venous oxygen saturation (central or mixed) may be influenced by the effects of mechanical ventilation. Therefore, central venous data should be interpreted with more caution when using higher mechanical power. On the contrary, carbon dioxide-derived parameters are more stable and similar between the two sampling sites, independently of mechanical power or positive end expiratory pressures.

[Evolution, controversies, and exploration of the nature of the definition of acute respiratory distress syndrome]

Acute respiratory distress syndrome (ARDS) is a collection of clinical syndromes characterized by a variety of heterogeneous causes. It includes diffuse lung diseases of various etiologies that ultimately lead to refractory hypoxia and severe acute respiratory failure. Despite advances in research and treatment of ARDS, its incidence and mortality continue to pose significant challenges in clinical practice. Since its inception in 1967, the definition of ARDS has undergone several revisions that have generated controversy and influenced the implementation of diagnostic and treatment strategies. At present, ARDS remains a formidable obstacle to both diagnosis and treatment. This article undertakes a comprehensive review of the evolution of ARDS definitions, examines the current diagnostic paradigm, and explores its far-reaching consequences. Our aim is to identify research directions, both in the realm of basic science and clinical practice, that are consistent with the nature of this complex disorder.

Positive end-expiratory pressure during one-lung ventilation for preventing atelectasis after video-assisted thoracoscopic surgery: a triple-arm, randomized controlled trial

BACKGROUND

There is little evidence regarding the benefits of lung-protective ventilation in patients undergoing one-lung ventilation for thoracic surgery. This study aimed to determine the optimal level of positive end-expiratory pressure (PEEP) during one-lung ventilation for minimizing postoperative atelectasis through lung ultrasonography.

METHODS

A total of 142 adult patients scheduled for video-assisted thoracoscopic surgery at Seoul National University Hospital between May 2019 and February 2020 were enrolled in this study. Patients were randomly assigned to different groups: 1) PEEP 3 cmH2O group; 2) PEEP 6 cmH2O group; and 3) PEEP 9 cmH2O group during one-lung ventilation. The lung ultrasound score was used to evaluate lung aeration using ultrasonography 1 hour after surgery.

RESULTS

The 1-hour post-surgery lung ultrasound scores were 8.1±2.5, 6.8±2.6, and 5.9±2.6 in the PEEP 3, 6, and 9 cmH2O groups, respectively (P<0.001). The PEEP 3 cmH2O group showed significantly higher lung ultrasound scores than the PEEP 6 (adjusted P=0.034) and 9 cmH2O groups (adjusted P<0.001). The PaO2/FiO2 ratio measured at 10 minutes after the end of one-lung ventilation was significantly lower in the PEEP 3 cmH2O group (392 [331 to 469]) than the PEEP 6 cmH2O (458 [384 to 530], adjusted P=0.018) or PEEP 9 cmH2O groups (454 [374 to 522], adjusted P=0.016).

CONCLUSIONS

Although the optimal level of PEEP during one-lung ventilation was not determined, the application of higher PEEP can prevent aeration loss in the ventilated lung after video-assisted thoracoscopic surgery under one-lung ventilation.

Sensory interventions to relieve dyspnoea in critically ill mechanically ventilated patients

BACKGROUND

In critically ill patients receiving mechanical ventilation, dyspnoea is frequent, severe and associated with an increased risk of neuropsychological sequelae. We evaluated the efficacy of sensory interventions targeting the brain rather than the respiratory system to relieve dyspnoea in mechanically ventilated patients.

METHODS

Patients receiving mechanical ventilation for ≥48 h and reporting dyspnoea (unidimensional dyspnoea visual analogue scale (Dyspnoea-VAS)) first underwent increased pressure support and then, in random order, auditory stimulation (relaxing music versus pink noise) and air flux stimulation (facial versus lower limb). Treatment responses were assessed using Dyspnoea-VAS, the Multidimensional Dyspnea Profile and measures of the neural drive to breathe (airway occlusion pressure (P 0.1) and electromyography of inspiratory muscles).

RESULTS

We included 46 patients (tracheotomy or intubation n=37; noninvasive ventilation n=9). Increasing pressure support decreased Dyspnoea-VAS by median 40 mm (p<0.001). Exposure to music decreased Dyspnoea-VAS compared with exposure to pink noise by median 40 mm (p<0.001). Exposure to facial air flux decreased Dyspnoea-VAS compared with limb air flux by median 30 mm (p<0.001). Increasing pressure support, but not music exposure and facial air flux, reduced P 0.1 by median 3.3 cmH2O (p<0.001).

CONCLUSIONS

In mechanically ventilated patients, sensory interventions can modulate the processing of respiratory signals by the brain irrespective of the intensity of the neural drive to breathe. It should therefore be possible to alleviate dyspnoea without resorting to pharmacological interventions or having to infringe the constraints of mechanical ventilation lung protection strategies by increasing ventilatory support.

2023 American Heart Association and American Academy of Pediatrics Focused Update on Neonatal Resuscitation: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

This 2023 focused update to the neonatal resuscitation guidelines is based on 4 systematic reviews recently completed under the direction of the International Liaison Committee on Resuscitation Neonatal Life Support Task Force. Systematic reviewers and content experts from this task force performed comprehensive reviews of the scientific literature on umbilical cord management in preterm, late preterm, and term newborn infants, and the optimal devices and interfaces used for administering positive-pressure ventilation during resuscitation of newborn infants. These recommendations provide new guidance on the use of intact umbilical cord milking, device selection for administering positive-pressure ventilation, and an additional primary interface for administering positive-pressure ventilation.

Comparative evaluation of stroke volume variation measured by pulse wave transit time and arterial pressure wave

BACKGROUND

Several monitors have been developed that measure stroke volume (SV) in a beat-to-beat manner. Accordingly, Stroke volume variation (SVV) induced by positive pressure ventilation is widely used to predict fluid responsiveness.

OBJECTIVE

The purpose of this study was to compare the ability of two different methods to predict fluid responsiveness using SVV, stroke volume variation by esCCO (esSVV) and stroke volume variation by FloTrac/VigileoTM (flSVV).

METHODS

esSVV, flSVV, and stroke volume index (SVI) by both monitoring devices of 37 adult patients who underwent laparotomy surgery, were measured. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

The area under the ROC curve (AUC) of esSVV was significantly higher than that of flSVV (p= 0.030). esSVV and flSVV showed cutoff values of 6.1% and 10% respectively, to predict an increase of more than 10% in SVI after fluid challenge. The Youden index for esSVV was higher than flSVV, even with a cutoff value between 6% and 8%.

CONCLUSION

Since esSVV and flSVV showed significant differences in AUC and cutoff values, the two systems were not comparable in predicting fluid responsiveness. Furthermore, it seems that SVV needs to be personalized to accurately predict fluid responsiveness for each patient.

Volume assured pressure support mode use for non-invasive ventilation in pediatrics

There has been increasing interest in utilizing volume assured pressure support (VAPS) modes of ventilation for children, which historically had only been favored in adult populations. In addition to patients with obesity hypoventilation syndrome, newer pediatric populations for which it has recently been prescribed include congenital central hypoventilation syndrome and children with neuromuscular disease such as Duchenne muscular dystrophy and spinal muscular atrophy. Given its expanding use in pediatrics, greater familiarity with VAPS is essential for pediatric pulmonologists and sleep physicians. This review article will highlight methods of initiation for this mode, specific ventilator settings, discussion of suitable pediatric patient populations, ventilator titrations via formal polysomnograms and detailed ventilator data downloads specific interpretation. Finally, common challenges to be aware of and how to troubleshoot relevant machine alarms will be reviewed.

[A theoretical study on a method for estimating dynamic intrinsic positive end-expiratory pressure in invasive mechanical ventilation]

OBJECTIVE

To explore a simple method for measuring the dynamic intrinsic positive end-expiratory pressure (PEEPi) during invasive mechanical ventilation.

METHODS

A 60-year-old male patient was admitted to the critical care medicine department of Dongying People's Hospital in September 2020. He underwent invasive mechanical ventilation treatment for respiratory failure due to head and chest trauma, and incomplete expiratory flow occurred during the treatment. The expiratory flow-time curve of this patient was served as the research object. The expiratory flow-time curve of the patient was observed, the start time of exhalation was taken as T0, the time before the initiation of inspiratory action (inspiratory force) was taken as T1, and the time when expiratory flow was reduced to zero by inspiratory drive (inspiratory force continued) was taken as T2. Taking T1 as the starting point, the follow-up tracing line was drawn according to the evolution trending of the natural expiratory curve before the T1 point, until the expiratory flow reached to 0, which was called T3 point. According to the time phase, the intrapulmonary pressure at the time just from expiratory to inspiratory (T1 point) was called PEEPi1. When the expiratory flow was reduced to 0 (T2 point), the intrapulmonary pressure with the inhaling power being removed hypothetically was called PEEPi2. And it was equal to positive end-expiratory pressure (PEEP) set in the ventilator at T3 point. The area under the expiratory flow-time curve (expiratory volume) between T0 and T1 was called S1. And it was S2 between T0 and T2, S3 between T0 and T3. After sedation, in the volume controlled ventilation mode, approximately one-third of the tidal volume was selected, and the static compliance of patient's respiratory system called "C" was measured using the inspiratory pause method. PEEPi1 and PEEP2 were calculated according to the formula "C = ΔV/ΔP". Here, ΔV was the change in alveolar volume during a certain period of time, and ΔP represented the change in intrapulmonary pressure during the same time period. This estimation method had obtained a National Invention Patent of China (ZL 2020 1 0391736.1).

RESULTS

(1) PEEPi1: according to the formula "C = ΔV/ΔP", the expiratory volume span from T1 to T3 was "S3-S1", and the intrapulmonary pressure decreased span was "PEEPi1-PEEP". So, C = (S3-S1)/(PEEPi1-PEEP), PEEPi1 = PEEP+(S3-S1)/C. (2)PEEPi2: the expiratory volume span from T2 to T3 was "S3-S2", and the intrapulmonary pressure decreased span was "PEEPi2-PEEP". So, C = (S3-S2)/(PEEPi2-PEEP), PEEPi2 = PEEP+(S3-S2)/C.

CONCLUSIONS

For patients with incomplete expiratory during invasive mechanical ventilation, the expiratory flow-time curve extension method can theoretically be used to estimate the dynamic PEEPi in real time.

Exerted force on the face mask in preterm infants at birth is associated with apnoea and bradycardia

BACKGROUND

During stabilisation of preterm infants at birth, a face mask is used to provide respiratory support. However, application of these masks may activate cutaneous stretch receptors of the trigeminal nerve, causing apnoea and bradycardia. This study investigated the amount of force exerted on the face mask during non-invasive ventilation of preterm infants at birth and whether the amount of exerted force is associated with apnoea and bradycardia.

METHODS

A prospective observational study was performed in preterm infants born <32 weeks of gestation who were stabilised at birth. During the first 10 minutes of respiratory support, we measured breathing and heart rate as well as the amount of force exerted on a face mask using a custom-made pressure sensor placed on top of the face mask.

RESULTS

Thirty infants were included (median (IQR) gestational age(GA) 28+3 (27+0-30+0) weeks, birthweight 1104 (878-1275) grams). The median exerted force measured was 297 (198-377) grams, ranging from 0 to 1455 grams. Significantly more force was exerted on the face mask during positive pressure ventilation when compared to CPAP (410 (256-556) vs 286 (190-373) grams, p = 0.009). In a binary logistic regression model, higher forces were associated with an increased risk of apnoea (OR = 1.607 (1.556-1.661), p < 0.001) and bradycardia (OR = 1.140 (1.102-1.180), p < 0.001) during the first 10 minutes of respiratory support at birth.

CONCLUSION

During mask ventilation, the median exerted force on a face mask was 297 grams with a maximum of 1455 grams. Higher exerted forces were associated apnoea and bradycardia during the first 10 minutes of respiratory support at birth.

PCV-VG combined individualized PEEP determination in one-lung ventilated patients with PEEP step change direction: A randomized controlled trial

INTRODUCTION

The efficacy of pressure-controlled volume-guaranteed ventilation (PCV-VG) combined with a gradient-directional change in positive end-expiratory pressure (PEEP) during one-lung ventilation (OLV) in patients who underwent thoracoscopic surgery was investigated.

METHODS

Ninety patients were randomly divided into the PC (PCV-VG + 5 cm H2 O fixed PEEP), PI (PCV-VG + incremental PEEP titration), and PD (PCV-VG + decremental PEEP titration) groups. Hemodynamic (heart rate [HR] and mean arterial pressure [MAP]), respiratory mechanics (Ppeak , Pmean, and Cdyn), and arterial blood gas (pH, PaCO2 , PaO2 , and PaO2 /FiO2 ) indices were evaluated at T1 (10 min of two-lung ventilation [TLV]), T2 (10 min of OLV), and T3 (10 min of recovery, TLV). Enzyme-linked immunosorbent assay was performed to detect neutrophil elastase (NE), clara cell secretory protein (CC16), and interleukin-8 (IL-8) levels at T1 and T3.

RESULTS

At T2 and T3 , Ppeak was lower in the PI and PD groups than in the PC group, while Pmean and Cdyn were higher than in the PC group. Ppeak in the PD group was lower than that in the PI group; however, Pmean was higher at T2 and T3 (P < 0.05). At T2 , PaO2 and PaO2 /FiO2 were higher, but PaO2 /FiO2 and VD /VT were lower in the PD and PI groups than in the PC group (P < 0.05). NE, CC16, IL-6, and IL-8 levels were elevated in all three groups at T3 , but the PI and PD groups had lower levels than the PC group (P < 0.05). The incidences of postoperative pulmonary complications (PPCs) and surgical intensive care unit hospitalizations in the PD and PI groups were much lower.

CONCLUSION

Gradient-directed altered PEEP titration could improve respiratory mechanics, arterial blood gases, and inflammatory responses and reduce the incidence of PPCs in patients undergoing thoracoscopic surgery.