Effects of cardiopulmonary resuscitation training on mortality rates after out-of-hospital cardiac arrest: protocol for a systematic review and meta-analysis

INTRODUCTION

An out-of-hospital cardiac arrest occurs at a rate of 67-170 cases per 100 000 inhabitants per year in Europe. The early recognition of the occurrence of a cardiac arrest, placing an emergency call, performing cardiopulmonary resuscitation (CPR) and performing defibrillation are the most important response measures. The objective of this systematic review and meta-analysis is to assess the effects of laypersons' CPR training with respect to CPR initiation rates, cardiovascular mortality rates, survival rate and the use of an automated external defibrillator.

METHODS AND ANALYSIS

The literature search will be performed in the following databases: MEDLINE, Web of Science, the Cochrane Central Register of Controlled Studies, CINAHL, HBI, TESEO and NTX. Intervention studies and quasi-experimental studies in which CPR training interventions were performed will be included. We will exclude studies in which the participants do not meet the inclusion criteria, without a control group and in which the methodology of the intervention applied is unclear. There will be no restrictions on publication date or language of publication. The risk of bias will be assessed using the Risk of Bias in Non-randomized Studies of Interventions tool for randomised controlled trials (RCT), non-RCT and quasi-experimental trials. Data analysis and synthesis will be performed using RevMan V.5.4.1 software. The findings will be reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance.

ETHICS AND DISSEMINATION

Ethical approval is not required, as only secondary data will be used. The findings will be published in a journal and presented at conferences.

PROSPERO REGISTRATION NUMBER

CRD42022365288.

Mechanisms of blunted muscle vasodilation during peripheral chemoreceptor stimulation in heart failure patients

We described recently that systemic hypoxia provokes vasoconstriction in heart failure (HF) patients. We hypothesized that either the exaggerated muscle sympathetic nerve activity and/or endothelial dysfunction mediate the blunted vasodilatation during hypoxia in HF patients. Twenty-seven HF patients and 23 age-matched controls were studied. Muscle sympathetic nerve activity was assessed by microneurography and forearm blood flow (FBF) by venous occlusion plethysmography. Peripheral chemoreflex control was evaluated through the inhaling of a hypoxic gas mixture (10% O(2) and 90% N(2)). Basal muscle sympathetic nerve activity was greater and basal FBF was lower in HF patients versus controls. During hypoxia, muscle sympathetic nerve activity responses were greater in HF patients, and forearm vasodilatation in HF was blunted versus controls. Phentolamine increased FBF responses in both groups, but the increase was lower in HF patients. Phentolamine and N(G)-monomethyl-l-arginine infusion did not change FBF responses in HF but markedly blunted the vasodilatation in controls. FBF responses to hypoxia in the presence of vitamin C were unchanged and remained lower in HF patients versus controls. In conclusion, muscle vasoconstriction in response to hypoxia in HF patients is attributed to exaggerated reflex sympathetic nerve activation and blunted endothelial function (NO activity). We were unable to identify a role for oxidative stress in these studies.