Mechanical Ventilation Management During Mechanical Chest Compressions

A retrospective comparison of mechanical cardio-pulmonary ventilation and manual bag valve ventilation in non-traumatic out-of-hospital cardiac arrests: A study from the Belgian cardiac arrest registry

BACKGROUND

The optimal ventilation modalities to manage out-of-hospital cardiac arrest (OHCA) remain debated. A specific pressure mode called cardio-pulmonary ventilation (CPV) may be used instead of manual bag ventilation (MBV). We sought to analyse the association between mechanical CPV and return of spontaneous circulation (ROSC) in non-traumatic OHCA.

METHODS

MBV and CPV were retrospectively identified in patients with non-traumatic OHCA from the Belgian Cardiac Arrest Registry. We used a two-level mixed-effects multivariable logistic regression analysis to determine the association between the ventilation modalities and outcomes. The primary and secondary study criteria were ROSC and survival with a Cerebral Performance Category (CPC) score of 1 or 2 at 30 days. Age, sex, initial rhythm, no-flow duration, low-flow duration, OHCA location, use of a mechanical chest compression device and Rankin status before arrest were used as covariables.

RESULTS

Between January 2017 and December 2021, 2566 patients with OHCA who fulfilled the inclusion criteria were included. 298 (11.6%) patients were mechanically ventilated with CPV whereas 2268 were manually ventilated. The use of CPV was associated with greater probability of ROSC both in the unadjusted (odds ratio: 1.28, 95% confidence interval [CI]: 1.01-1.63; p = 0.043) and adjusted analyses (adjusted odds ratio [aOR]: 2.16, 95%CI 1.37-3.41; p = 0.001) but not with a lower CPC score (aOR: 1.44, 95%CI 0.72-2.89; p = 0.31).

CONCLUSIONS

Compared with MBV, CPV was associated with an increased risk of ROSC but not with improved an CPC score in patients with OHCA. Prospective randomised trials are needed to challenge these results.

Acute Lung Injury after Cardiopulmonary Resuscitation: A Narrative Review

Although cardiopulmonary resuscitation (CPR) includes lifesaving maneuvers, it might be associated with a wide spectrum of iatrogenic injuries. Among these, acute lung injury (ALI) is frequent and yields significant challenges to post-cardiac arrest recovery. Understanding the relationship between CPR and ALI is determinant for refining resuscitation techniques and improving patient outcomes. This review aims to analyze the existing literature on ALI following CPR, emphasizing prevalence, clinical implications, and contributing factors. The review seeks to elucidate the pathogenesis of ALI in the context of CPR, assess the efficacy of CPR techniques and ventilation strategies, and explore their impact on post-cardiac arrest outcomes. CPR-related injuries, ranging from skeletal fractures to severe internal organ damage, underscore the complexity of managing post-cardiac arrest patients. Chest compression, particularly when prolonged and vigorous, i.e., mechanical compression, appears to be a crucial factor contributing to ALI, with the concept of cardiopulmonary resuscitation-associated lung edema (CRALE) gaining prominence. Ventilation strategies during CPR and post-cardiac arrest syndrome also play pivotal roles in ALI development. The recognition of CPR-related lung injuries, especially CRALE and ALI, highlights the need for research on optimizing CPR techniques and tailoring ventilation strategies during and after resuscitation.

Automatic Mechanical Ventilation vs Manual Bag Ventilation During CPR: A Pilot Randomized Controlled Trial

BACKGROUND

There is insufficient evidence supporting the theory that mechanical ventilation can replace the manual ventilation method during CPR.

RESEARCH QUESTION

Is using automatic mechanical ventilation (MV) feasible and comparable to the manual ventilation method during CPR?

STUDY DESIGN AND METHODS

This pilot randomized controlled trial compared MV and manual bag ventilation (BV) during CPR after out-of-hospital cardiac arrest (OHCA). Patients with medical OHCA arriving at the ED were randomly assigned to two groups: an MV group using a mechanical ventilator and a BV group using a bag valve mask. Primary outcome was any return of spontaneous circulation (ROSC). Secondary outcomes were changes of arterial blood gas analysis results during CPR. Tidal volume, minute volume, and peak airway pressure were also analyzed.

RESULTS

A total of 60 patients were enrolled, and 30 patients were randomly assigned to each group. There were no statistically significant differences in basic characteristics of OHCA patients between the two groups. The rate of any return of spontaneous circulation was 56.7% in the MV group and 43.3% in the BV group, indicating no significant (P = .439) difference between the two groups. There were also no statistically significant differences in changes of PH, Pco2, Po2, bicarbonate, or lactate levels during CPR between the two groups (P values = .798, 0.249, .515, .876, and .878, respectively). Significantly lower tidal volume (P < .001) and minute volume (P = .009) were observed in the MV group.

INTERPRETATION

In this pilot trial, the use of MV instead of BV during CPR was feasible and could serve as a viable alternative. A multicenter randomized controlled trial is needed to create sufficient evidence for ventilation guidelines during CPR.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT05550454; URL: www.

CLINICALTRIALS

gov.

Effective ventilation and chest compressions during neonatal resuscitation - the role of the respiratory device

BACKGROUND

The success of cardiopulmonary resuscitation (CPR) in newborns largely depends on effective lung ventilation; however, a direct randomized comparison using different available devices has not yet been performed.

METHODS

Thirty-six professionals were exposed to a realistic newborn CPR scenario. Ventilation with either a bag-valve mask (BVM), T-piece, or ventilator was applied in a randomized manner during CPR using a Laerdal manikin. The primary outcome was the number of unimpaired inflations, defined as the peak of the inflation occurring after chest compression and lasting at least 0.35 s before the following chest compression takes place. The secondary outcomes were tidal volume delivered and heart compression rate. To simulate potential distractions, the entire scenario was performed with or without a quiz. Statistically, a mixed model assessing fixed effects for experience, profession, device, and distraction was used to analyze the data. For direct comparison, one-way ANOVA with Bonferroni's correction was applied.

RESULTS

The number of unimpaired inflations was highest in health care professionals using the BVM with a mean ± standard deviation of 12.8 ± 2.8 (target: 15 within 30 s). However, the tidal volumes were too large in this group with a tidal volume of 42.5 ± 10.9 ml (target: 25-30 ml). The number of unimpaired breaths with the mechanical ventilator and the T-piece system were 11.6 (±3.6) and 10.1 (±3.7), respectively. Distraction did not change these outcomes, except for the significantly lower tidal volumes with the T-piece during the quiz.

CONCLUSIONS

In summary, for our health care professionals, ventilation using the mechanical ventilator seemed to provide the best approach during CPR, especially in a population of preterm infants prone to volutrauma.

The effects of mechanical versus bag-valve ventilation on gas exchange during cardiopulmonary resuscitation in emergency department patients: A randomized controlled trial (CPR-VENT)

INTRODUCTION

Effective ventilation is crucial for successful cardiopulmonary resuscitation (CPR). Previous studies indicate that higher arterial oxygen levels (PaO2) during CPR increase the chances of successful resuscitation. However, the advantages of mechanical ventilators over bag-valve ventilation for achieving optimal PaO2 during CPR remain uncertain.

METHOD

We conducted a randomized trial involving non-traumatic adult cardiac arrest patients who received CPR in the ED. After intubation, patients were randomly assigned to ventilate with a mechanical ventilator (MV) or bag valve ventilation (BV). In MV group, ventilation settings were: breath rate 10/minute, tidal volume 6-7 ml/kg, inspiratory time 1 second, positive end-expiratory pressure 0 cm water, inspiratory oxygen fraction (FiO2) 100%. The primary outcome was to compare the difference in PaO2 from arterial blood gases (ABG) obtained 4-10 minutes later during CPR between both groups.

RESULTS

Sixty patients were randomized (30 in each group). The study population consisted of: 57% male, median age 62 years, 37% received bystander CPR, and 20% had an initial shockable rhythm. Median time from arrest to intubation was 24 minutes. The median PaO2 was not significantly different in the BV compared to MV [36.5 mmHg (14.0-70.0) vs. 29.0 mmHg (15.0-70.0), P = 0.879]. Other ABG parameters and rates of return of spontaneous circulation and survival were not different.

CONCLUSIONS

In ED patients with refractory cardiac arrest, arterial oxygen levels during CPR were comparable between patients ventilated with MV and BV. Mechanical ventilation is at least feasible and safe during CPR in intubated cardiac arrest patients.

Effect of automated head-thorax elevation during chest compressions on lung ventilation: a model study

Our goal was to investigate the effects of head-thorax elevation (HUP) during chest compressions (CC) on lung ventilation. A prospective study was performed on seven human cadavers. Chest was automatically compressed-decompressed in flat position and during progressive HUP from 18 to 35°. Lung ventilation was measured with electrical impedance tomography. In each cadaver, 5 sequences were randomly performed: one without CC at positive end-expiratory pressure (PEEP) 0cmH2O, 3 s with CC at PEEP0, 5 or 10cmH2O and 1 with CC and an impedance threshold device at PEEP0cmH2O. The minimal-to-maximal change in impedance (VTEIT in arbitrary unit a.u.) and the minimal impedance in every breathing cycle (EELI) the) were compared between flat, 18°, and 35° in each sequence by a mixed-effects model. Values are expressed as median (1st-3rd quartiles). With CC, between flat, 18° and 35° VTEIT decreased at each level of PEEP. It was 12416a.u. (10,689; 14,442), 11,239 (7667; 13,292), and 6457 (4631; 9516), respectively, at PEEP0. The same was true with the impedance threshold device. EELI/VTEIT significantly decreased from - 0.30 (- 0.40; - 0.15) before to - 1.13 (- 1.70; - 0.61) after the CC (P = 0.009). With HUP lung ventilation decreased with CC as compared to flat position. CC are associated with decreased in EELI.

Ventilatory improvement with mechanical ventilator versus bag in non-traumatic out-of-hospital cardiac arrest: SYMEVECA study, phase 1

AIM

To analyze differences in ventilatory parameters and outcome with different ventilatory methods during CPR.

METHODS

Pragmatic prospective quasi-experimental study in out-of-hospital urban environment. Patients over 18 years of age in non-traumatic cardiac arrest, attended by an emergency medical service between April 2021 and September 2022, were included. Two groups were compared according to the ventilatory method: mechanical ventilator (IPPV, tidal volume 7 ml/kg, frequency 10-12 bpm) or manual resuscitator bag. The main variables of interest are those of gasometry performed 15 minutes after intubation or when spontaneous circulation is recovered and final outcome. Patients were followed up to hospital discharge.

RESULTS

Of the 359 patients attended, 150 were included (71 in IPPV and 79 with a bag). In patients with arterial blood gases, pCO2 was 67.8 ± 21.1 in the IPPV group vs 95.9 ± 39.0 mmHg in the bag group (p = 0.006) and pH was 7.00 ± 0.18 vs 6.92 ± 0.18 (p = 0.18). With a venous sample, the pCO2 was 68.1 ± 18.9 vs 89.5 ± 26.5 mmHg (p < 0.001) and the pH was 7.03 ± 0.15 vs 6.94 ± 0.17 (p = 0.005), respectively. Survival with CPC 1-2 to hospital discharge was 15.6% with IPPV and 11.3% with bag (p = 0.44).

CONCLUSION

The use of a mechanical ventilator in IPPV was associated with a better ventilatory status during CPR compared to the use of the bag, without conclusive data regarding its clinical repercussion with the sample collected.

Comparison of clinical outcomes in critical patients undergoing different mechanical ventilation modes: a systematic review and network meta-analysis

Purpose

To evaluate the effects of different mechanical ventilation modes on critical patients.

Methods

PubMed, Embase, Web of science, and Cochrane Library databases were searched from their inception to November 15, 2022 for randomized controlled trials on the application of different mechanical ventilation modes in critical patients. Two researchers independently screened the literature, extracted data, and assessed the risk of bias in the included studies. R4.2.1 was used for this network meta-analysis.

Results

Twenty-eight RCTs involving 3,189 patients were included. The interventions in these RCTs included NAVA (neurally adjusted ventilatory assist), PAV (proportional assist ventilation), ASV (adaptive support ventilation), Smartcare/PS (Smartcare/pressure support), PSV (pressure support ventilation), PSV_ATC (pressure support ventilation_automatic tube compensation), and SIMV (synchronized intermittent mandatory ventilation). The network meta-analysis showed that, compared with the PSV group, there was no significant difference in duration of mechanical ventilation, duration of ICU stay, and hospital stay between NAVA, SIMV, AVS, PAV, Smartcare/PS, and PSV_ATC groups. Compared with PSV, PAV improved the success rate of withdrawal of ventilator [OR = 3.07, 95%CI (1.21, 8.52)]. Compared with PSV and PAV, NAVA reduced mortality in the ICU [OR = 0.63, 95%CI (0.43, 0.93); OR = 0.45, 95%CI (0.21, 0.97)].

Conclusion

NAVA can reduce mortality in ICU, and PAV may increase the risk of withdrawal of the ventilator. There was no significant difference between PSV and other mechanical ventilation modes (NAVA, SIMV, AVS, PAV, Smartcare/PS, and PSV_ATC) in the duration of mechanical ventilation, duration of ICU stay, or hospital stay. Due to the limitations, more high-quality studies are needed to verify these findings.

The Beginning of an ECLS Center: First Successful ECPR in an Emergency Department in Romania-Case-Based Review

According to the latest international resuscitation guidelines, extracorporeal cardiopulmonary resuscitation (ECPR) involves the utilization of extracorporeal membrane oxygenation (ECMO) in specific patients experiencing cardiac arrest, and it can be considered in situations where standard cardiopulmonary resuscitation efforts fail if they have a potentially reversible underlying cause, among which we can also find hypothermia. In cases of cardiac arrest, both witnessed and unwitnessed, hypothermic patients have higher chances of survival and favorable neurological outcomes compared to normothermic patients. ECPR is a multifaceted procedure that requires a proficient team, specialized equipment, and comprehensive multidisciplinary support within a healthcare system. However, it also carries the risk of severe, life-threatening complications. With the increasing use of ECPR in recent years and the growing number of centers implementing this technique outside the intensive care units, significant uncertainties persist in both prehospital and emergency department (ED) settings. Proper organization is crucial for an ECPR program in emergency settings, especially given the challenges and complexities of these treatments, which were previously not commonly used in ED. Therefore, within a narrative review, we have incorporated the initial case of ECPR in an ED in Romania, featuring a successful resuscitation in the context of severe hypothermia (20 °C) and a favorable neurological outcome (CPC score of 1).

Use of a Portable Mechanical Ventilator during Cardiopulmonary Resuscitation is Feasible, Improves Respiratory Parameters, and Prevents the Decrease of Dynamic Lung Compliance

BACKGROUND

For practical and protective ventilation during cardiopulmonary resuscitation (CPR), a 150-grams mechanical ventilator (VLP2000E) that limits peak inspiratory pressure (PIP) during simultaneous ventilation with chest compressions was developed.

OBJECTIVES

To evaluate the feasibility of VLP2000E ventilation during CPR and to compare monitored parameters versus bag-valve ventilation.

METHODS

A randomized experimental study with 10 intubated pigs per group. After seven minutes of ventricular fibrillation, 2-minute CPR cycles were delivered. All animals were placed on VLP2000E after achieving return of spontaneous circulation (ROSC).

RESULTS

Bag-valve and VLP2000E groups had similar ROSC rate (60% vs. 50%, respectively) and arterial oxygen saturation in most CPR cycles, different baseline tidal volume [0.764 (0.068) vs. 0.591 (0.123) L, p = 0.0309, respectively] and, in 14 cycles, different PIP [52 (9) vs. 39 (5) cm H2O, respectively], tidal volume [0.635 (0.172) vs. 0.306 (0.129) L], ETCO2[14 (8) vs. 27 (9) mm Hg], and peak inspiratory flow [0.878 (0.234) vs. 0.533 (0.105) L/s], all p < 0.0001. Dynamic lung compliance (≥ 0.025 L/cm H2O) decreased after ROSC in bag-valve group but was maintained in VLP2000E group [0.019 (0.006) vs. 0.024 (0.008) L/cm H2O, p = 0.0003].

CONCLUSIONS

VLP2000E ventilation during CPR is feasible and equivalent to bag-valve ventilation in ROSC rate and arterial oxygen saturation. It produces better respiratory parameters, with lower airway pressure and tidal volume. VLP2000E ventilation also prevents the significant decrease of dynamic lung compliance observed after bag-valve ventilation. Further preclinical studies confirming these findings would be interesting.

Mechanical ventilation with ten versus twenty breaths per minute during cardio-pulmonary resuscitation for out-of-hospital cardiac arrest: A randomised controlled trial

AIM OF THE STUDY

This study sought to assess the effects of increasing the ventilatory rate from 10 min^-1 to 20 min^-1 using a mechanical ventilator during cardio-pulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) on ventilation, acid-base-status, and outcomes.

METHODS

This was a randomised, controlled, single-centre trial in adult patients receiving CPR including advanced airway management and mechanical ventilation offered by staff of a prehospital physician response unit (PRU). Ventilation was conducted using a turbine-driven ventilator (volume-controlled ventilation, tidal volume 6 ml per kg of ideal body weight, positive end-expiratory pressure (PEEP) 0 mmHg, inspiratory oxygen fraction (FiO₂) 100%), frequency was pre-set at either 10 or 20 breaths per minute according to week of randomisation. If possible, an arterial line was placed and blood gas analysis was performed.

RESULTS

The study was terminated early due to slow recruitment. 46 patients (23 per group) were included. Patients in the 20 min^-1 group received higher expiratory minute volumes [8.8 (6.8-9.9) vs. 4.9 (4.2-5.7) litres, p < 0.001] without higher mean airway pressures [11.6 (9.8-13.6) vs. 9.8 (8.5-12.0) mmHg, p = 0.496] or peak airway pressures [42.5 (36.5-45.9) vs. 41.4 (32.2-51.7) mmHg, p = 0.895]. Rates of ROSC [12 of 23 (52%) vs. 11 of 23 (48%), p = 0.768], median pH [6.83 (6.65-7.05) vs. 6.89 (6.80-6.97), p = 0.913], and median pCO₂ [78 (51-105) vs. 86 (73-107) mmHg, p > 0.999] did not differ between groups.

CONCLUSION

20 instead of 10 mechanical ventilations during CPR increase ventilation volumes per minute, but do not improve CO₂ washout, acidaemia, oxygenation, or rate of ROSC.

CLINICALTRIALS

gov Identifier: NCT04657393.

Mechanical ventilation during cardiopulmonary resuscitation: influence of positive end-expiratory pressure and head-torso elevation

BACKGROUND

Efficient ventilation is important during cardiopulmonary resuscitation (CPR). Nevertheless, there is insufficient knowledge on how the patient's position affects ventilatory parameters during mechanically assisted CPR. We studied ventilatory parameters at different positive end-expiratory pressure (PEEP) levels and when using an inspiratory impedance valve (ITD) during horizontal and head-up CPR (HUP-CPR).

METHODS

In this human cadaver experimental study, we measured tidal volume (V_T) and pressure during CPR at different randomized PEEP levels (0, 5 or 10 cmH₂O) or with an ITD. CPR was performed, in the following order: horizontal (FLAT), at 18° and then at 35° head-thorax elevation. During the inspiratory phase we measured the net tidal volume (V_T) adjusted to predicted body weight (V_TPBW), reversed airflow (RAF), and maximum and minimum airway pressure (P_max and P_min).

RESULTS

Using ten thawed fresh-frozen cadavers we analyzed the inspiratory phase of 1843 respiratory cycles, 229 without CPR and 1614 with CPR. In a mixed linear model, thoracic position and PEEP significantly impacted V_TPBW (p < 0.001 for each), and the insufflation time, thoracic position and PEEP significantly affected the RAF (p < 0.001 for each) and P_max (p < 0.001). For P_min, only PEEP was significant (p < 0.001). In subgroup analysis, at 35° V_TPBW and P_max were significantly reduced compared with the flat or 18° position.

CONCLUSION

When using mechanical ventilation during CPR, it seems that the PEEP level and patient position are important determinants of respiratory parameters. Moreover, tidal volume seems to be lower when the thorax is positioned at 35°.

Cardiac arrest: An interdisciplinary scoping review of clinical literature from 2020

Objectives

The Interdisciplinary Cardiac Arrest Research Review (ICARE) group was formed in 2018 to conduct an annual search of peer-reviewed literature relevant to cardiac arrest. Now in its third year, the goals of the review are to highlight annual updates in the interdisciplinary world of clinical cardiac arrest research with a focus on clinically relevant and impactful clinical and population-level studies from 2020.

Methods

A search of PubMed using keywords related to clinical research in cardiac arrest was conducted. Titles and abstracts were screened for relevance and sorted into 7 categories: Epidemiology & Public Health Initiatives; Prehospital Resuscitation, Technology & Care; In-Hospital Resuscitation & Post-Arrest Care; Prognostication & Outcomes; Pediatrics; Interdisciplinary Guidelines & Reviews; and a new section dedicated to the coronavirus disease 2019 (COVID-19) pandemic. Screened manuscripts underwent standardized scoring of methodological quality and impact on the respective fields by reviewer teams lead by a subject matter expert editor. Articles scoring higher than 99 percentiles by category were selected for full critique. Systematic differences between editors' and reviewers' scores were assessed using Wilcoxon signed-rank test.

Results

A total of 3594 articles were identified on initial search; of these, 1026 were scored after screening for relevance and deduplication, and 51 underwent full critique. The leading category was Prehospital Resuscitation, Technology & Care representing 35% (18/51) of fully reviewed articles. Four COVID-19 related articles were included for formal review that was attributed to a relative lack of high-quality data concerning cardiac arrest and COVID-19 specifically by the end of the 2020 calendar year. No significant differences between editor and reviewer scoring were found among review articles (P = 0.697). Among original research articles, section editors scored a median 1 point (interquartile range, 0-3; P < 0.01) less than reviewers.

Conclusions

Several clinically relevant studies have added to the evidence base for the management of cardiac arrest patients including methods for prognostication of neurologic outcome following arrest, airway management strategy, timing of coronary intervention, and methods to improve expeditious performance of key components of resuscitation such as chest compressions in adults and children.

Prehospital Cardiac Arrest Airway Management: An NAEMSP Position Statement and Resource Document

Airway management is a critical component of out-of-hospital cardiac arrest (OHCA) resuscitation. Multiple cardiac arrest airway management techniques are available to EMS clinicians including bag-valve-mask (BVM) ventilation, supraglottic airways (SGAs), and endotracheal intubation (ETI). Important goals include achieving optimal oxygenation and ventilation while minimizing negative effects on physiology and interference with other resuscitation interventions. NAEMSP recommends:Based on the skill of the clinician and available resources, BVM, SGA, or ETI may be considered as airway management strategies in OHCA.Airway management should not interfere with other key resuscitation interventions such as high-quality chest compressions, rapid defibrillation, and treatment of reversible causes of the cardiac arrest.EMS clinicians should take measures to avoid hyperventilation during cardiac arrest resuscitation.Where available for clinician use, capnography should be used to guide ventilation and chest compressions, confirm and monitor advanced airway placement, identify return of spontaneous circulation (ROSC), and assist in the decision to terminate resuscitation.

Point-of-care ultrasound in cardiorespiratory arrest (POCUS-CA): narrative review article

The POCUS-CA (Point-of-care ultrasound in cardiac arrest) is a diagnostic tool in the Intensive Care Unit and Emergency Department setting. The literature indicates that in the patient in a cardiorespiratory arrest it can provide information of the etiology of the arrest in patients with non-defibrillable rhythms, assess the quality of compressions during cardiopulmonary resuscitation (CPR), and define prognosis of survival according to specific findings and, thus, assist the clinician in decision-making during resuscitation. This narrative review of the literature aims to expose the usefulness of ultrasound in the setting of cardiorespiratory arrest as a tool that allows making a rapid diagnosis and making decisions about reversible causes of this entity. More studies are needed to support the evidence to make ultrasound part of the resuscitation algorithms. Teamwork during cardiopulmonary resuscitation and the inclusion of ultrasound in a multidisciplinary approach is important to achieve a favorable clinical outcome.

Reliability of mechanical ventilation during continuous chest compressions: a crossover study of transport ventilators in a human cadaver model of CPR

Background

Previous studies have stated that hyperventilation often occurs in cardiopulmonary resuscitation (CPR) mainly due to excessive ventilation frequencies, especially when a manual valve bag is used. Transport ventilators may provide mandatory ventilation with predetermined tidal volumes and without the risk of hyperventilation. Nonetheless, interactions between chest compressions and ventilations are likely to occur. We investigated whether transport ventilators can provide adequate alveolar ventilation during continuous chest compression in adult CPR.

Methods

A three-period crossover study with three common transport ventilators in a cadaver model of CPR was carried out. The three ventilators ‘MEDUMAT Standard²’, ‘Oxylog 3000 plus’, and ‘Monnal T60’ represent three different interventions, providing volume-controlled continuous mandatory ventilation (VC-CMV) via an endotracheal tube with a tidal volume of 6 mL/kg predicted body weight. Proximal airflow was measured, and the net tidal volume was derived for each respiratory cycle. The deviation from the predetermined tidal volume was calculated and analysed. Several mixed linear models were calculated with the cadaver as a random factor and ventilator, height, sex, crossover period and incremental number of each ventilation within the period as covariates to evaluate differences between ventilators.

Results

Overall median deviation of net tidal volume from predetermined tidal volume was − 21.2 % (IQR: 19.6, range: [− 87.9 %; 25.8 %]) corresponding to a tidal volume of 4.75 mL/kg predicted body weight (IQR: 1.2, range: [0.7; 7.6]). In a mixed linear model, the ventilator model, the crossover period, and the cadaver’s height were significant factors for decreased tidal volume. The estimated effects of tidal volume deviation for each ventilator were − 14.5 % [95 %-CI: −22.5; −6.5] (p = 0.0004) for ‘Monnal T60’, − 30.6 % [95 %-CI: −38.6; −22.6] (p < 0.0001) for ‘Oxylog 3000 plus’ and − 31.0 % [95 %-CI: −38.9; −23.0] (p < 0.0001) for ‘MEDUMAT Standard²’.

Conclusions

All investigated transport ventilators were able to provide alveolar ventilation even though chest compressions considerably decreased tidal volumes. Our results support the concept of using ventilators to avoid excessive ventilatory rates in CPR. This experimental study suggests that healthcare professionals should carefully monitor actual tidal volumes to recognise the occurrence of hypoventilation during continuous chest compressions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13049-021-00921-2.

ECMO in Cardiac Arrest: A Narrative Review of the Literature

Cardiac arrest (CA) is a frequent cause of death and a major public health issue. To date, conventional cardiopulmonary resuscitation (CPR) is the only efficient method of resuscitation available that positively impacts prognosis. Extracorporeal membrane oxygenation (ECMO) is a complex and costly technique that requires technical expertise. It is not considered standard of care in all hospitals and should be applied only in high-volume facilities. ECMO combined with CPR is known as ECPR (extracorporeal cardiopulmonary resuscitation) and permits hemodynamic and respiratory stabilization of patients with CA refractory to conventional CPR. This technique allows the parallel treatment of the underlying etiology of CA while maintaining organ perfusion. However, current evidence does not support the routine use of ECPR in all patients with refractory CA. Therefore, an appropriate selection of patients who may benefit from this procedure is key. Reducing the duration of low blood flow by means of performing high-quality CPR and promoting access to ECPR, may improve the survival rate of the patients presenting with refractory CA. Indeed, patients who benefit from ECPR seem to carry better neurological outcomes. The aim of this present narrative review is to present the most recent literature available on ECPR and to clarify its potential therapeutic role, as well as to provide an in-depth explanation of equipment and its set up, the patient selection process, and the patient management post-ECPR.