ReviewVentilation rate in adults with a tracheal tube during cardiopulmonary resuscitation: A systematic review
Introduction
Current guidelines recommend a ventilation rate of 10 min−1 without pausing chest compressions during cardiopulmonary resuscitation (CPR) with a tracheal tube in place [1], [2]. Numerous observational studies show that ventilation rates greater than 10 min−1 are common during actual CPR [3], [4], [5], [6], [7], [8], [9], [10], [11]. A reduced ventilation rate could be sufficient to maintain a normal ventilation to perfusion ratio during CPR as the cardiac output generated by chest compressions is only 10–15% of normal [12]. An increased ventilation rate during CPR can increase the mean intrathoracic pressure reducing venous return to the heart, increase lung volume and pulmonary vascular resistance, reduce cardiac output, and decrease coronary perfusion pressure and aortic blood pressure [5], [6], [13], [14], [15], [16]. Positive pressure ventilation can also increase intracranial pressure and thus reduce cerebral perfusion [13], [15], [17]. Conversely, the relative negative intrathoracic pressures generated during the decompression phase of chest compression can increase the return of venous blood to the heart and increase blood flow to the myocardium and the brain during chest compressions [15], [17], [18], [19]. Positive pressure ventilation could therefore negate these beneficial effects of chest wall recoil [15], [20].
The optimal ventilation rate to ensure adequate gas exchange without reducing the perfusion of vital organs is uncertain [21]. In a pig study, increasing the compression: ventilation (C:V) ratio from 15:2 to 15:1 improved coronary and cerebral perfusion pressure [17]. In another pig study, there was improved coronary perfusion pressure with a ventilation rate of 10 min−1 compared to 35 min−1 but no difference in 1 h and 24 h survival [22]. Other studies do not report similar improvements in organ perfusion [23], [24]. During the first five minutes of CPR, a ventilation rate of 2 min−1 resulted in lower carotid blood flow and brain oxygen tension than a ventilation rate of 10 min−1 [21]. In another study, a lack of ventilation during CPR was associated with atelectasis, arterial hypoxaemia and compromised haemodynamics [25].
This systematic review was conducted as part of the 2015 International Liaison Committee on Resuscitation (ILCOR) Consensus on Science and Treatment Recommendation (CoSTR) process [26], [27], [28]. We evaluated whether in adults with cardiac arrest and a secure airway (tracheal tube), the current recommended ventilation rate of 10 min−1, compared to any other rate during CPR, improves outcomes.
Section snippets
Methods
This systematic review followed the process described by ILCOR for its 2015 Consensus on Science and Treatment Recommendation (CoSTR) process [26]. Worksheet evaluation experts reviewed the search strategy and its findings. The method was informed and validated against the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist [29].The PRISMA checklist is completed and attached as Supplementary Appendix A. In addition, the Grading of Recommendations, Assessment,
Study selection
The search strategy identified 839 potentially relevant studies off which 680 were excluded after screening the titles and abstracts (Fig. 1). Of the 159 remaining studies, 148 were excluded after reviewing the full text. Eleven studies of ventilation with a tracheal tube during CPR that assessed ventilation rate were included in the systematic review.
Study characteristics
One human observational study with 67 subjects [3] and 10 animal studies including 234 pigs and 30 dogs met the inclusion criteria [5], [6], [16]
Discussion
The current ventilation rate recommendation of 10 min−1 during CPR with a tracheal tube is a weak recommendation based on very low quality evidence. We did not identify any human studies that address the critical PICO outcomes (survival or survival with favourable neurologic/functional outcome at discharge/30 days, 60 days, 180 days, and/or 1 year) [28]. For the important outcome of ROSC, we only identified very low quality evidence (downgraded for very serious risk of bias and indirectness, and
Conclusion
A ventilation rate recommendation of 10 min−1 during adult CPR with a tracheal tube and no pauses for chest compression is a very weak recommendation based on very low quality evidence. Ventilation rate is only one of many airway and breathing interventions. Future studies will need to look at a combination of factors to help us understand the role of ventilation rate during CPR with a tracheal tube.
Disclaimer
This review includes information on resuscitation questions developed through the C2015 Consensus on Science and Treatment Recommendations (CoSTR) process, managed by the International Liaison Committee on Resuscitation (www.ilcor.org/seers). The questions were developed by ILCOR Task Forces, using strict conflict of interest guidelines. In general, each question was assigned to two experts to complete a detailed structured review of the literature, and complete a detailed evidence evaluation.
Author contributions
Study concept and design: Gino Vissers (GV), Koenraad G. Monsieurs (KGM) Jasmeet Soar (JS). Performance of literature searches and selection of articles: GV, KGM, JS. Analysis and interpretation of data: GV, KGM, JS. Creating figures, tables and graphs: GV. Drafting of the manuscript: GV, JS. Critical revision of the manuscript: KGM, JS. Study supervision: KGM, JS. All the authors approved the final manuscript.
Funding and support
No funding was received from any source with regards to the writing of this article.
Conflicts of interest statement
GV has no conflicts of interest. JS is an editor of the journal Resuscitation and Chair of the ILCOR ALS Task Force. KGM is Honorary Secretary of ILCOR.
Acknowledgements
The authors would like to acknowledge the contributions of Dr Eddy Lang, and Dr Peter Morley with regards to data collection, analysis, and methodology.
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