Effect of continuous compression and 30:2 cardiopulmonary resuscitation on cerebral microcirculation in a porcine model of cardiac arrest

Continuous compression with asynchronous ventilation improves CPR prognosis? A meta-analysis from human and animal studies

BACKGROUND

The cardiopulmonary resuscitation (CPR) compression to ventilation strategy remains controversial. We conducted a meta-analysis to compare the outcomes between continuous chest compressions CPR with asynchronous ventilation (CCC-CPR) and interrupted chest compressions CPR with synchronous ventilation (ICC-CPR) in cardiac arrest.

METHODS

PubMed, Web of Science, Embase, MEDLINE (Ovid/LWW) and the Cochrane Libraries were searched up from inception to July 31, 2022. Human and animal studies comparing CCC-CPR versus ICC-CPR were included. Outcome variables were return of spontaneous circulation (ROSC), time to ROSC, survival to discharge, 1-month survival, survival at 4 h, good neurological function, mean arterial pressure (MAP) and other clinical parameters. Jadad Scale and Newcastle-Ottawa Scale were used to assess the study quality and risk of bias.

RESULTS

The systematic search identified eight studies on humans and twelve studies on animal trials. There were no significant differences in ROSC (odd ratios [OR] 1.07; 95% confidence interval [CI]: 0.86-1.32; P = 0.55), survival to hospital discharge (OR 1.04; 95%CI 0.77-1.42; P = 0.79), 1-month survival (OR 1.07; 95%CI 0.84-1.36; P = 0.57), and good neurological outcome (OR 0.92; 95%CI 0.84-1.01, P = 0.09) between CCC-CPR and ICC-CPR in human studies. In animal trials, CCC-CPR had significantly higher rate of ROSC (OR = 1.81; 95% CI: 0.94-3.49; P = 0.07), survival at 4 h (OR 2.57; 95% CI: 1.16-5.72; P = 0.02) and MAP (mean difference [MD] 0.79, 95% CI: 0.04-1.53; P = 0.04), even though no significant differences in ROSC time, arterial potential of hydrogen (pH) and partial tension of carbon dioxide (PaCO2).

CONCLUSION

CCC-CPR did not show superiority in human outcomes compared with ICC-CPR, but its effect value was significantly increased in animal experiments. We should take the positive outcomes from animals and apply them to human models, and more physiological mechanisms need to be confirmed in CPR patients with different compression-ventilation strategies to improve the prognosis of cardiac arrest.

Pralidoxime-Induced Potentiation of the Pressor Effect of Adrenaline and Hastened Successful Resuscitation by Pralidoxime in a Porcine Cardiac Arrest Model

PURPOSE

Pralidoxime potentiated the pressor effect of adrenaline and facilitated restoration of spontaneous circulation (ROSC) after prolonged cardiac arrest. In this study, we hypothesised that pralidoxime would hasten ROSC in a model with a short duration of untreated ventricular fibrillation (VF). We also hypothesised that potentiation of the pressor effect of adrenaline by pralidoxime would not be accompanied by worsening of the adverse effects of adrenaline.

METHODS

After 5 min of VF, 20 pigs randomly received either pralidoxime (40 mg/kg) or saline, in combination with adrenaline, during cardiopulmonary resuscitation (CPR). Coronary perfusion pressure (CPP) during CPR, and ease of resuscitation were compared between the groups. Additionally, haemodynamic data, severity of ventricular arrhythmias, and cerebral microcirculation were measured during the 1-h post-resuscitation period. Cerebral microcirculatory blood flow and brain tissue oxygen tension (PbtO₂) were measured on parietal cortices exposed through burr holes.

RESULTS

All animals achieved ROSC. The pralidoxime group had higher CPP during CPR (P = 0.014) and required a shorter duration of CPR (P = 0.024) and smaller number of adrenaline doses (P = 0.024). During the post-resuscitation period, heart rate increased over time in the control group, and decreased steadily in the pralidoxime group. No inter-group differences were observed in the incidences of ventricular arrhythmias, cerebral microcirculatory blood flow, and PbtO₂.

CONCLUSION

Pralidoxime improved CPP and hastened ROSC in a model with a short duration of untreated VF. The potentiation of the pressor effect of adrenaline was not accompanied by the worsening of the adverse effects of adrenaline.

Microcirculatory blood flow during cardiac arrest and cardiopulmonary resuscitation does not correlate with global hemodynamics: an experimental study

Background

Current research highlights the role of microcirculatory disorders in post-cardiac arrest patients. Affected microcirculation shows not only dissociation from systemic hemodynamics but also strong connection to outcome of these patients. However, only few studies evaluated microcirculation directly during cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). The aim of our experimental study in a porcine model was to describe sublingual microcirculatory changes during CA and CPR using recent videomicroscopic technology and provide a comparison to parameters of global hemodynamics.

Methods

Cardiac arrest was induced in 18 female pigs (50 ± 3 kg). After 3 min without treatment, 5 min of mechanical CPR followed. Continuous hemodynamic monitoring including systemic blood pressure and carotid blood flow was performed and blood lactate was measured at the end of baseline and CPR. Sublingual microcirculation was assessed by the Sidestream Dark Field (SDF) technology during baseline, CA and CPR. Following microcirculatory parameters were assessed off-line separately for capillaries (≤20 µm) and other vessels: total and perfused vessel density (TVD, PVD), proportion of perfused vessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI).

Results

In comparison to baseline the CA small vessel microcirculation was only partially preserved: TVD 15.64 (13.59–18.48) significantly decreased to 12.51 (10.57–13.98) mm/mm², PVD 15.57 (13.56–17.80) to 5.53 (4.17–6.60) mm/mm², PPV 99.64 (98.05–100.00) to 38.97 (27.60–46.29) %, MFI 3.00 (3.00–3.08) to 1.29 (1.08–1.58) and HI increased from 0.08 (0.00–0.23) to 1.5 (0.71–2.00), p = 0.0003 for TVD and <0.0001 for others, respectively. Microcirculation during ongoing CPR in small vessels reached 59–85 % of the baseline values: TVD 13.33 (12.11–15.11) mm/mm², PVD 9.34 (7.34–11.52) mm/mm², PPV 72.34 (54.31–87.87) %, MFI 2.04 (1.58–2.42), HI 0.65 (0.41–1.07). The correlation between microcirculation and global hemodynamic parameters as well as to lactate was only weak to moderate (i.e. Spearman’s ρ 0.02–0.51) and after adjustment for multiple correlations it was non-significant.

Conclusions

Sublingual microcirculatory parameters did not correlate with global hemodynamic parameters during simulated porcine model of CA and CPR. SDF imaging provides additional information about tissue perfusion in the course of CPR.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0934-5) contains supplementary material, which is available to authorized users.