aEEG and NIRS during transition and resuscitation after birth: Promising additional tools; an observational study

Aim of the study

During resuscitation no routine cerebral monitoring is available. We aimed at monitoring cerebral activity and oxygenation continuously during neonatal transition and resuscitation.

Methods

Neonates ≥34 weeks of gestation born via cesarean section were included. Cerebral activity was continuously measured with amplitude-integrated-EEG (aEEG) and cerebral oxygenation (rSO₂) with near-infrared-spectroscopy (NIRS) during the first 10 min after birth. For quantitative analysis of aEEG every minute the mean minimum amplitude (V_min) and maximum amplitude (V_max) was determined. Uncompromised neonates were compared to neonates in need of resuscitation.

Results

Out of 224 eligible neonates 31 uncompromised and 15 in need of respiratory support were included. Uncompromised neonates showed higher values for V_min in the third minute and higher values for V_max in the third and fourth minute compared to the tenth minute post-partum. In uncompromised neonates rSO₂ values during the first 6 min after birth were lower compared to minute ten. Neonates in need of respiratory support had lower rSO₂ values over the first 8 min after birth compared to minute ten.

Conclusions

This is the first study demonstrating that monitoring of aEEG and NIRS to measure cerebral activity and oxygenation during immediate postpartum transition is feasible. During transition compromised neonates requiring resuscitation showed a different cerebral activity pattern compared to uncompromised neonates.     

Cerebral metabolic rate of oxygen (CMRO2) in pig brain determined by PET after resuscitation from cardiac arrest

Aim

To assess the regional vulnerability to ischemic damage and perfusion/metabolism mismatch of reperfused brain following restoration of spontaneous circulation (ROSC) after cardiac arrest.

Method

We used positron emission tomography (PET) to map cerebral metabolic rate of oxygen (CMRO₂), cerebral blood flow (CBF) and oxygen extraction fraction (OEF) in brain of young pigs at intervals after resuscitation from cardiac arrest. After obtaining baseline PET recordings, ventricular fibrillation of 10 min duration was induced, followed by mechanical closed-chest cardiopulmonary resuscitation (CPR) in conjunction with i.v. administration of 0.4 U/kg of vasopressin. After CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). CBF and CMRO₂ were mapped and voxelwise maps of OEF were calculated at times of 60, 180, and 300 min after ROSC.

Results

There was hypoperfusion throughout the telencephalon at 60 min, with a return towards baseline values at 300 min. In contrast, there was progressively increasing CBF in cerebellum throughout the observation period. The magnitude of CMRO₂ decreased globally after ROSC, especially in cerebral cortex. The magnitude of OEF in cerebral cortex was 60% at baseline, tended to increase at 60 min after ROSC, and declined to 50% thereafter, thus suggesting transition to an ischemic state.

Conclusion

The cortical regions tended most vulnerable to the ischemic insult with an oligaemic pattern and a low CMRO₂ whereas the cerebellum instead showed a pattern of luxury perfusion.     

Regional cerebral oxygen saturation after cardiac arrest in 60 patients—A prospective outcome study

Introduction

Non-invasive near-infrared spectroscopy (NIRS) offers the possibility to determine regional cerebral oxygen saturation (rSO₂) in patients with cardiac arrest. Limited data from recent studies indicate a potential for early prediction of neurological outcome.

Methods

Sixty cardiac arrest patients were prospectively enrolled, 22 in-hospital cardiac arrest (IHCA) and 38 out-of-hospital cardiac arrest (OHCA) patients respectively. NIRS of frontal brain was started after return of spontaneous circulation (ROSC) during admission to ICU and was continued until normothermia. Outcome was determined at ICU discharge by the Pittsburgh Cerebral Performance Category (CPC) and 6 months after cardiac arrest.

Results

A good outcome (CPC 1–2) was achieved in 23 (38%) patients, while 37 (62%) had a poor outcome (CPC 3–5). Patients with good outcome had significantly higher rSO₂ levels (CPC 1–2: rSO₂ 68%; CPC 3–5: rSO₂ 58%; p < 0.01). For good and poor outcome median rSO₂ within the first 24 h period was 66% and 59% respectively and for the following 16 h period 68% and 59% (p < 0.01). Outcome prediction by area of rSO₂ below a critical threshold of rsO₂ = 50% within the first 40 h yielded 70% specificity and 86% sensitivity for poor outcome.

Conclusion

On average, rSO₂ within the first 40 h after ROSC is significantly lower in patients with poor outcome, but rSO₂ ranges largely overlap between outcome groups. Our data indicate limited potential for prediction of poor outcome by frontal brain rSO₂ measurements.     

Intra-arrest selective brain cooling improves success of resuscitation in a porcine model of prolonged cardiac arrest

Aims of study

We have previously demonstrated that early intra-nasal cooling improved post-resuscitation neurological outcomes. The present study utilizing a porcine model of prolonged cardiac arrest investigated the effects of intra-nasal cooling initiated at the start of cardiopulmonary resuscitation (CPR) on resuscitation success. Our hypothesis was that rapid nasal cooling initiated during “low-flow” improves return of spontaneous resuscitation (ROSC).

Methods

In 16 domestic male pigs weighing 40 ± 3 kg, VF was electrically induced and untreated for 15 min. Animals were randomized to either head cooling or control. CPR was initiated and continued for 5 min before defibrillation was attempted. Coincident with starting CPR, the hypothermic group was cooled with a RhinoChill™ device which produces evaporative cooling in the nasal cavity of pigs. No cooling was administrated to control animals. If ROSC was not achieved after defibrillation, CPR was resumed for 1 min prior to the next defibrillation attempt until either successful resuscitation or for a total of 15 min.

Main results

Seven of eight animals in the hypothermic group (87.5%) and two of eight animals in control group (25%) (p = 0.04) were successfully resuscitated. At ROSC, brain temperature was increased from baseline by 0.3 °C in the control group, and decreased by 0.1 °C in the hypothermic animals. Pulmonary artery temperature was above baseline in both groups.

Conclusion

Intra-nasal cooling initiated at the start of CPR significantly improves the success of resuscitation in a porcine model of prolonged cardiac arrest. This may have occurred by preventing brain hyperthermia.     

Correlations between hemodynamic, oxygenation and tissue perfusion parameters during asphyxial cardiac arrest and resuscitation in a pediatric animal model

Aim

To analyze the correlations between hemodynamic, oxygenation and tissue perfusion values in an infant animal model of asphyctic cardiac arrest (ACA).

Methods

A prospective observational animal study was performed in seventy one, two month-old piglets. CA was induced by removal of mechanical ventilation and was followed by advanced life support after at least 10 min. Correlations between hemodynamic [heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke volume index (SVI) and intrathoracic blood index (ITBI) measured by PiCCO method], blood gas values (arterial and central venous saturation), and tissue perfusion values [intramucosal gastric pH (pHi), and tissue oxygenation (cerebral and renal saturation)] were analyzed during asphyxia, resuscitation and after return of spontaneous circulation (ROSC).

Results

Among global hemodynamic parameters, the only moderate significant correlation observed was between CI and ITBI (r = .551). Among tissue oxygenation/perfusion values, a moderate to good significant correlation (r = .460-.763) between arterial oxygen saturation, central venous, renal and cerebral oxygen saturation was observed. Lactic acid, potassium (K) and pHi were correlated (r = .561-.639), but no correlation was found between them and tissue oxygenation parameters. Global hemodynamic parameters (CI, HR, MAP) did not correlate with renal and cerebral saturations and tissue perfusion parameters.

Conclusions

During ACA and after ROSC global hemodynamic parameters do not correlate with oxygenation and tissue perfusion values. Additional studies which assess the potential usefulness of tissue oxygenation/perfusion parameters during cardiac arrest and ROSC are needed.     

A feasibility study of cerebral oximetry monitoring during the post-resuscitation period in comatose patients following cardiac arrest

Background

One of the major causes of death and neurological injury after cardiac arrest is delayed ischemia combined with oxygen free radical mediated reperfusion injury. Consequently determining the optimal balance between oxygen delivery and uptake in the brain using a reliable non-invasive monitoring system during the post-resuscitation period is of importance. In this observational study, we evaluated the feasibility of using cerebral oximetry during the post-resuscitation period in order to identify changes in regional cerebral oxygen saturation (rSO₂) and its association with survival to discharge.

Methods

21 consecutive patients admitted to the intensive care units following cardiac arrest had cerebral oximetry monitoring carried out for 48 h. Mean rSO₂ values were collected during the first 24 h and then again during the subsequent 24–48 h of the post-resuscitation period.

Results

43% (n = 9) patients survived to hospital discharge and 57% (n = 12) died. Amongst all patients the median (IQR) rSO₂% was 65.5% (62.6–68.2) in the first 24-h following ROSC and increased to 72.1% (64.6–73.7) (p = 0.11) in the subsequent 24–48 h. The median (IQR) rSO₂% during the first 24 h in patients who survived to discharge compared to those who did not survive were significantly higher 68.2% (66.0–71.0) vs. 62.9% (56.5–66.0), p = 0.01). During the subsequent 24–48 h period, while a difference in the rSO₂ between survivors and non-survivors was noted, this did not achieve statistical significance (median (IQR): 73.7 (70.2–74.0) vs. 66.5 (58.2–72.1), p = 0.11).

Conclusions

Our study indicates that the use of cerebral oximetry is feasible during the post resuscitation period after cardiac arrest. Further studies are needed to determine whether cerebral oximetry may be used as a novel non-invasive monitoring system to evaluate changes in the balance between cerebral oxygen delivery and uptake during the post-resuscitation period.     

Passive leg raising during cardiopulmonary resuscitation in out-of-hospital cardiac arrest—Does it improve circulation and outcome?

Background

Passive leg raising (PLR), to augment the artificial circulation, was deleted from cardiopulmonary resuscitation (CPR) guidelines in 1992. Increases in end-tidal carbon dioxide (P_ETCO₂) during CPR have been associated with increased pulmonary blood flow reflecting cardiac output. Measurements of P_ETCO₂ after PLR might therefore increase our understanding of its potential value in CPR. We also observed the alteration in P_ETCO₂ in relation to the return of spontaneous circulation (ROSC) and no ROSC.

Methods and results

The P_ETCO₂ was measured, subsequent to intubation, in 126 patients suffering an out-of-hospital cardiac arrest (OHCA), during 15 min or until ROSC. Forty-four patients were selected by the study protocol to PLR 35 cm; 21 patients received manual chest compressions and 23 mechanical compressions. The PLR was initiated during uninterrupted CPR, 5 min from the start of P_ETCO₂ measurements. During PLR, an increase in P_ETCO₂ was found in all 44 patients within 15 s (p = 0.003), 45 s (p = 0.002) and 75 s (p = 0.0001). Survival to hospital discharge was 7% among patients with PLR and 1% among those without PLR (p = 0.12). Among patients experiencing ROSC (60 of 126), we found a marked increase in P_ETCO₂ 1 min before the detection of a palpable pulse.

Conclusion

Since PLR during CPR appears to increase P_ETCO₂ after OHCA, larger studies are needed to evaluate its potential effects on survival. Further, the measurement of P_ETCO₂ could help to minimise the hands-off periods and pulse checks.     

S-100B is superior to NSE, BDNF and GFAP in predicting outcome of resuscitation from cardiac arrest with hypothermia treatment

Objective

To conduct a pilot study to evaluate the blood levels of brain derived neurotrophic factor (BDNF), glial fibrillary acidic protein (GFAP), neuron specific enolase (NSE) and S-100B as prognostic markers for neurological outcome 6 months after hypothermia treatment following resuscitation from cardiac arrest.

Design

Prospective observational study.

Setting

One intensive care unit at Uppsala University Hospital.

Patients

Thirty-one unconscious patients resuscitated after cardiac arrest.

Interventions

None.

Measurements and main results

Unconscious patients after cardiac arrest with restoration of spontaneous circulation (ROSC) were treated with mild hypothermia to 32-34 °C for 26 h. Time from cardiac arrest to target temperature was measured. Blood samples were collected at intervals of 1-108 h after ROSC. Neurological outcome was assessed with Glasgow-Pittsburgh cerebral performance category (CPC) scale at discharge from intensive care and again 6 months later, when 15/31 patients were alive, of whom 14 had a good outcome (CPC 1-2). Among the predictive biomarkers, S-100B at 24 h after ROSC was the best, predicting poor outcome (CPC 3-5) with a sensitivity of 87% and a specificity of 100%. NSE at 96 h after ROSC predicted poor outcome, with sensitivity of 57% and specificity of 93%. BDNF and GFAP levels did not predict outcome. The time from cardiac arrest to target temperature was shorter for those with poor outcome.

Conclusions

The blood concentration of S-100B at 24 h after ROSC is highly predictive of outcome in patients treated with mild hypothermia after cardiac arrest.     

The state of systemic circulation, collapsed or preserved defines the need for hyperoxic or normoxic resuscitation in neonatal mice with hypoxia-ischemia

Background

The return of spontaneous circulation (ROSC) is a primary goal of resuscitation. For neonatal resuscitation the International Liaison Committee on Resuscitation (ILCOR) recommends oxygen concentrations ranging from 21% to 100%.

Aims and methods

This study (a) compared the efficacy of resuscitation with room air (RA) or 100% O₂ in achieving ROSC in 46 neonatal mice with circulatory collapse induced by lethal hypoxia-ischemia (HI) and (b) determined whether re-oxygenation with RA or 100% O₂ alters the extent of HI cerebral injury in mice with preserved systemic circulation (n = 31). We also compared changes in generation of reactive oxygen species (ROS) in cerebral mitochondria in response to re-oxygenation with RA or 100% O₂.

Result

In HI-mice with collapsed circulation re-oxygenation with 100% O₂ versus RA resulted in significantly greater rate of ROSC. In HI-mice with preserved systemic circulation and regional (unilateral) cerebral ischemia the restoration of cerebral blood flow was significantly faster upon re-oxygenation with 100% O₂, than RA. However, no difference in the extent of brain injury was detected. Regardless of the mode of re-oxygenation, reperfusion in these mice was associated with markedly accelerated ROS production in brain mitochondria.

Conclusion

In murine HI associated with circulatory collapse the resuscitation limited to re-oxygenation with 100% O₂ is superior to the use of RA in achievement of the ROSC. However, in HI-mice with preserved systemic circulation hyperoxic re-oxygenation has no benefit over the normoxic brain recovery.     

Continuous chest compression resuscitation in arrested swine with upper airway inspiratory obstruction

Background

This study was designed to compare 24-h survival rates and neurological function of swine in cardiac arrest treated with one of three forms of simulated basic life support CPR.

Methods

Thirty swine were randomized equally among three experimental groups to receive either 30:2 CPR with an unobstructed endotracheal tube (ET) or continuous chest compression (CCC) CPR with an unobstructed ET or CCC CPR with a collapsable rubber sleeve on the ET allowing air outflow but completely restricting air inflow. The swine were anesthetized but not paralyzed. Two min of untreated VF was followed by 9 min of simulated single rescuer bystander CPR. In the 30:2 CPR group, each set of 30 chest compressions was followed by a 15-s pause to simulate the realistic duration of interrupted chest compressions required for a single rescuer to deliver 2 mouth-to-mouth ventilations. The other two groups were provided continuous chest compressions (CCC) without assisted ventilations. At 11 min post-arrest a biphasic defibrillation shock (150 J) was administered followed by a period of advanced cardiac life support.

Results

In the 30:2 group, 8 of 10 animals had good neurological function at 24-h post-resuscitation. In the CCC open airway group, 10 of 10, and in the CCC inspiratory obstructed group, 9 of 10. The number of shocks (P < 0.05) and epinephrine doses (P < 0.05) required for ROSC was greater in the 30:2 CPR group than in the other two groups.

Conclusions

There were no differences in 24-h survival with good neurological function among these three different CPR protocols.     

Comparing the survival between extracorporeal rescue and conventional resuscitation in adult in-hospital cardiac arrests: Propensity analysis of three-year data

Aim

Extracorporeal cardiopulmonary resuscitation (ECPR) has been shown to have survival benefit over conventional CPR (CCPR) in patients with in-hospital cardiac arrest of cardiac origin. We compared the survival of patients who had return of spontaneous beating (ROSB) after ECPR with the survival of those who had return of spontaneous circulation (ROSC) after conventional CPR.

Methods

Propensity score-matched cohort of adults with in-hospital prolonged CPR (>10 min) of cardiac origin in a university-affiliated tertiary extracorporeal resuscitation center were included in this study. Fifty-nine patients with ROSB after ECPR and 63 patients with sustained ROSC by CCPR were analyzed. Main outcome measures were survival at hospital discharge, 30 days, 6 months, and one year, and neurological outcome.

Results

There was no statistical difference in survival to discharge (29.1% of ECPR responders vs. 22.2% of CCPR responders, p = 0.394) and neurological outcome at discharge and one year later. In the propensity score-matched groups, 9 out of 27 ECPR patients survived to one month (33.3%) and 7 out of 27 CCPR patients survived (25.9%). Survival analysis showed no survival difference (HR: 0.856, p = 0.634, 95% CI: 0.453-1.620) between the groups, either at 30 days or at the end of one year (HR: 0.602, p = 0.093, 95% CI: 0.333-1.088).

Conclusions

This study failed to demonstrate a survival difference between patients who had ROSB after institution of ECMO and those who had ROSC after conventional CPR. Further studies evaluating the role of ECMO in conventional CPR rescued patients are warranted.     

Effects of sustained abdominal aorta compression on coronary perfusion pressures and restoration of spontaneous circulation during cardiopulmonary resuscitation in swine

Objectives

The present study was undertaken to explore whether sustained abdominal aorta compression-cardiopulmonary resuscitation (SAAC-CPR), as a means, can raise coronary perfusion pressure (CPP) as well as restoration of spontaneous circulation (ROSC) during CPR. In the present study, we hypothesised that SAAC-CPR elevates CPP during CPR and improves ROSC, without causing liver laceration.

Methods

Animals were randomised into one of two groups (Standard CPR and SAAC-CPR). Ten domestic swine (22-25 kg) were anaesthetised, intubated and mechanically ventilated. Ventricular fibrillation was induced, and after 3 min of untreated ventricular fibrillation, the animals were treated with standard CPR (with simplex chest compression (SCC) and epinephrine) or SAAC-CPR (SCC with sustained abdominal aorta compression, without epinephrine). CPP and ROSC were compared.

Results

SCC with sustained abdominal aorta compression (SCC + SAAC) significantly increased CPP in comparison with SCC during CPR (p < 0.05). The increase in CPP with SCC + SAAC is equivalent to that achieved with epinephrine (p > 0.05). All animals in the standard CPR and SAAC-CPR groups restored spontaneous circulation. No liver damage was found in post-mortem examinations of the swine subjects.

Conclusions

During CPR, non-invasive SAAC can rapidly and reversibly raise the CPP as much as can epinephrine and is especially suitable for out-of-hospital CPR.     

Ethyl pyruvate enhances intra-resuscitation hemodynamics in prolonged ventricular fibrillation arrest

Aims

As the duration of untreated cardiac arrest increases, the effectiveness of standard therapies declines, and may be more harmful than helpful. We investigated the hemodynamic, metabolic and anti-inflammatory effects of Ringer's ethyl pyruvate solution (REPS) versus Ringer's solution (RS) in the acute model of prolonged porcine arrest.

Methods

Seventeen mixed-breed swine were induced into ventricular fibrillation (VF) and left untreated for 8 min. CPR was begun using a mechanical chest compression device at a rate of 100 per minute. At the onset of CPR, animals were randomly assigned to treatment with either 25 mL/kg of RS or 25 mL/kg of REPS containing 40 mg/kg of ethyl pyruvate, infused over 5 min in blinded fashion. CPR continued with administration of a drug cocktail at 2 min and the first rescue shock was delivered at minute 13 of VF. Animals having ROSC were supported with standardized care for 2 h.

Results

Both groups had 100% ROSC and 100% 2-h survival. The REPS group exhibited higher median CPP (27.3 mmHg) than the control group (16.5 mmHg) by 3 min of CPR, which continued throughout the duration of CPR (p = 0.02). The median time to hypotension following ROSC was 9.64 min in the REPS group and 7.25 min in controls (p = 0.04) and there was a non-significant trend of decreased use of vasopressors for the duration of resuscitation. There was no difference in systemic or cerebral metabolism between groups. There were non-significant trends of decreased IL-6, increased Il-10 and decreased mesenteric bacterial colony growth in those treated with REPS when compared to RS.

Conclusions

The administration of REPS with CPR significantly improved intra- and post-resuscitation hemodynamics in this swine model of prolonged cardiac arrest, but did not definitely change the metabolic or inflammatory profile during the acute resuscitation period.     

Perfluorocarbon induced intra-arrest hypothermia does not improve survival in a swine model of asphyxial cardiac arrest

Background

Pulseless electrical activity is an important cause of cardiac arrest. Our purpose was to determine if induction of hypothermia with a cold perfluorocarbon-based total liquid ventilation (TLV) system would improve resuscitation success in a swine model of asphyxial cardiac arrest/PEA.

Methods

Twenty swine were randomly assigned to control (C, no ventilation, n = 11) or TLV with pre-cooled PFC (n = 9) groups. Asphyxia was induced by insertion of a stopper into the endotracheal tube, and continued in both groups until loss of aortic pulsations (LOAP) was reached, defined as a pulse pressure less than 2 mmHg. The TLV animals underwent asphyxial arrest for an additional 2 min after LOAP, followed by 3 min of hypothermia, prior to starting CPR. The C animals underwent 5 min of asphyxia beyond LOAP. Both groups then underwent CPR for at least 10 min. The endpoint was the resumption of spontaneous circulation maintained for 10 min.

Results

Seven of 9 animals achieved resumption of spontaneous circulation (ROSC) in the TLV group vs. 5 of 11 in the C group (p = 0.2). The mean pulmonary arterial temperature was lower in total liquid ventilation animals starting 4 min after induction of hypothermia (TLV 36.3 ± 0.2 °C vs. C 38.1 ± 0.2 °C, p < 0.0001). Arterial pO₂ was higher in total liquid ventilation animals at 2.5 min of CPR (TLV 76 ± 12 mmHg vs. C 44 ± 2 mmHg; p = 0.03).

Conclusion

Induction of moderate hypothermia using perfluorocarbon-based total liquid ventilation did not improve ROSC success in this model of asphyxial cardiac arrest.     

Near infrared spectrophotometry (cerebral oximetry) in predicting the return of spontaneous circulation in out-of-hospital cardiac arrest

Aim

We assessed out-of-hospital cardiac arrest patients’ cerebral oxygenation during cardiopulmonary resuscitation (CPR) using near infrared spectrophotometry (NIRS). We evaluated the relation between a rise in patients’ cerebral saturation values between the start and end of CPR and return of spontaneous circulation.

Materials and methods

Twenty-three patients with unwitnessed out-of-hospital cardiac arrest and brought to our emergency department by emergency ambulance were evaluated. Cerebral saturations from time of start of CPR were measured using NIRS. CPR was performed for a maximum of 30 min. The relation between cerebral saturations in patients with or without return of spontaneous circulation was then evaluated.

Results

Twenty-three patients, 12 (52.2%) female and 11 (47.8%) male, with a mean age of 64.09 ± 13.66 were included. A correlation was determined between a rise in cerebral saturation measured throughout CPR and the return of spontaneous circulation (P < .001).

Conclusion

Patients whose cerebral saturation values measured with NIRS rise during CPR have a higher post-resuscitation survival rate. Monitoring of patients during CPR with this non-invasive technique may be a good method for predicting return of spontaneous circulation.     

Improving the neurological prognosis following OHCA using real-time evaluation of cerebral tissue oxygenation

Background

The neurological prognosis is poor for patients suffering from out-of-hospital cardiac arrest (OHCA), in the absence of bystander cardio pulmonary resuscitation (CPR), and showing asystole as the initial waveform. However, such patients have the potential of resuming social activity if cerebral tissue oxygen saturation can be preserved.

The prognostic value of end tidal carbon dioxide during cardiac arrest: A systematic review

Introduction

Cardiac arrest is a common presentation to the emergency care system. The decision to terminate CPR is often challenging to heath care providers. An accurate, early predictor of the outcome of resuscitation is needed. The purpose of this systematic review is to evaluate the prognostic value of ETCO₂ during cardiac arrest and to explore whether ETCO₂ values could be utilised as a tool to predict the outcome of resuscitation.

Method

Literature search was performed using Medline and EMBASE databases to identify studies that evaluated the relationship between ETCO₂ during cardiac arrest and outcome. Studies were thoroughly evaluated and appraised. Summary of evidence and conclusions were drawn from this systematic literature review.

Results

23 observational studies were included. The majority of studies showed that ETCO₂ values during CPR were significantly higher in patients who later developed ROSC compared to patients who did not. Several studies suggested that initial ETCO₂ value of more than 1.33 kPa is 100% sensitive for predicting survival making ETCO₂ value below 1.33 kPa a strong predictor of mortality. These studies however had several limitations and the 100% sensitivity for predicting survival was not consistent among all studies.

Conclusion

ETCO₂ values during CPR do correlate with the likelihood of ROSC and survival and therefore have prognostic value. Although certain ETCO₂ cut-off values appears to be a strong predictor of mortality, the utility of ETCO₂ cut-off values during CPR to accurately predict the outcome of resuscitation is not fully established. Therefore, ETCO₂ values cannot be used as a mortality predictor in isolation.     

Sex differences in cardiac injury after severe haemorrhage and ventricular fibrillation in pigs

Aim of the study

Experimental studies have shown sex differences in haemodynamic response and outcome after trauma and haemorrhagic shock. We recently reported that female sex protects against cerebral injury after exsanguination cardiac arrest (CA), independent of sexual effects of hormones. The current study examines if female sex is also cardioprotective.

Methods

In this study 21 sexually immature piglets (12 males and 9 females) were subjected to 5 min of haemorrhagic shock followed by 2 min of ventricular fibrillation and 8 min of cardiopulmonary resuscitation (CPR). Volume resuscitation was started during CPR with intravenous administration of 3 ml kg⁻¹ hypertonic saline-dextran (HSD) solution for 20 min. Sexually immature animals were used to differentiate innate sex differences from the effects of sexual hormones. Sex differences in haemodynamics, myocardial injury (troponin I), and short-term survival (3-h) were evaluated.

Results

After resuscitation female animals had a higher blood pressure, lower heart rate, lower troponin I concentrations, and higher survival rate (100% and 63% in 3 h) despite comparable sex hormone levels.

Conclusions

After resuscitation from haemorrhage and circulatory arrest, haemodynamic parameters are better preserved and myocardial injury is smaller in female piglets. This difference in outcome is independent of sexual hormones.