Immediate coronary angiogram in comatose survivors of out-of-hospital cardiac arrest--an Australian study

Introduction

The role of immediate coronary angiography and percutaneous coronary intervention (angio ± PCI), amongst comatose survivors of out-of-hospital cardiac arrest is unclear. This study was undertaken to evaluate if immediate angio ± PCI compared to no initial intervention improves neurological outcome at hospital discharge amongst comatose survivors of out-of-hospital pulseless ventricular tachycardia (pVT) or ventricular fibrillation (VF).

Methods

All patients admitted to Intensive Care Unit (ICU) following an out-of-hospital VF/pVT arrest from 1/1/2003 to 31/12/2008 were included. Outcome of patients who underwent immediate angio ± PCI was compared to those who did not undergo any intervention before admission to ICU. Good outcome was defined as survival to hospital discharge with Cerebral Performance Category (CPC) score of 1 or 2.

Results

Thirty-five patients (30 Males, 5 Females, mean age 60.3 ± 10.1), underwent angio ± PCI prior to ICU admission. A further 35 patients (20 Males, 15 Females, mean age 61.1 ± 17.6 years) were admitted directly to ICU without undergoing any intervention. Forty percent (14/35) of patients who had immediate coronary intervention survived to hospital discharge with a good outcome compared to 31% (11/35) patients who did not undergo any intervention. After adjusting for other covariates, the probability of good outcome at hospital discharge was related to severity of illness (SAPS-II) score at ICU admission (adj OR = 0.87, 95% CI 0.81–0.94, p < 0.01). Immediate angio ± PCI compared to no intervention was associated with an improved outcome but this difference was statistically not significant (adj OR 1.32, 95% CI 0.26–7.87, p = 0.78).

Conclusion

Immediate angio ± PCI in comatose survivors of out-of-hospital VF/pVT arrest did not lead to better neurological outcome at hospital discharge.     

Investigation of the possibility of using ischemia-modified albumin as a novel and early prognostic marker in cardiac arrest patients after cardiopulmonary resuscitation

Background

Early and accurate prediction of survival to hospital discharge following resuscitation after cardiac arrest (CA) is a major challenge. Our aim was to investigate the levels of ischemia-modified albumin (IMA) and malondialdehyde (MDA) in CA patients and whether IMA levels are valuable early marker of post-cardiopulmonary resuscitation prognosis in CA patients.

Methods

We enrolled 52 in- or out-of-hospital CA patients, with 47 healthy volunteers as the control group (CG). Blood samples were taken for IMA and MDA measurement at the beginning or within 5 min of commencement of CPR. The patients were classified according to the Glasgow Outcome Score (GOS) into a poor outcome group (POG) and a good outcome group (GOG).

Results

Mean IMA levels were higher in POG (0.25 ± 0.07 ABSU) than in GOG (0.19 ± 0.07 ABSU, p = 0.002) and also than CG (0.16 ± 0.04 ABSU, p = 0.0001). The IMA levels were not significantly higher in GOG than in CG (p = 0.32). The mean MDA levels in POG (0.77 ± 0.27 nmol/ml) were comparable to the levels in GOG (0.75 ± 0.18 nmol/ml, p > 0.05), but were significantly higher than in CG (0.60 ± 0.15 nmol/ml, p = 0.001). MDA levels were not significantly higher in GOG than in CG (p = 0.06). The optimum cut-off point for IMA maximizing sensitivity and specificity was 0.235 ABSU, with sensitivity of 65.8% and specificity of 78.6%. The corresponding +PV and −PV were 85.3% and 45.8%, respectively.

Conclusion

In conclusion, though the result may not be applied clinically in every patient, the ischemia-modified albumin may be a valuable prognostic marker in cardiac arrest patients following CPR.     

Effects of bone marrow mesenchymal stem cells in a rat model of myocardial infarction

Aim

Infusion of bone marrow mesenchymal stem cells (MSCs) improves myocardial function following myocardial infarction (MI). The mechanisms, however, remain controversial. This study was to investigate changes of MSCs in vivo after administration into myocardial infarcted rats. Our hypothesis was that MSCs might differentiate into contractile myocytes and improve myocardial function in vivo.

Methods

MI was induced in 21 Sprague–Dawley rats by ligation of the left anterior descending artery. One week after ligation, 18 rats were randomized to receive MSCs labeled with PKH26 in a phosphate buffer solution (PBS) by direct injection into the infarcted myocardium. The remaining 3 rats received PBS alone as placebo. An additional 3 non-ligated rats served as a normal group to obtain normal myocytes.

Results

Every week for 6 weeks, hearts from 3 rats injected with MSCs were harvested to observe single cardiomyocytes. Although each week numerous round MSCs were found in the hearts of animals treated with MSCs, beating cardiomyocyte-like cells labeled with PKH26 were observed at the sixth week. The contractility of cardiomyocyte-like cells was the same to that of the unlabeled contractile native cardiomyocytes at the sixth week and that of the normal group (10.71 ± 1.59 vs. 11.09 ± 3.42 vs. 11.21 ± 2.16, p > 0.05). The contractility of cardiomyocyte-like cells was greater than cells both from the first week (10.71 ± 1.59 vs. 7.37 ± 3.47, p < 0.01) and the second week (10.71 ± 1.59 vs. 8.08 ± 3.11, p < 0.05) which was associated with significantly increased ejection fraction.

Conclusions

MSCs can differentiate into beating cardiomyocytes in a rat model of MI and improve myocardial function.     

Out-of-hospital cardiac arrest in patients treated with primary PCI for STEMI. Long-term follow up data from EUROTRANSFER registry

Objectives

Our aim was to describe long-term outcome of OHCA patients in a cohort of STEMI patients treated by primary PCI based on the EUROTRANSFER Registry data.

Background

The occurrence of cardiac arrest is associated with impaired survival. There are limited number of studies reporting outcome of STEMI patients with out-of-hospital cardiac arrest (OHCA) treated by primary percutaneous coronary intervention (PCI). The recently published resuscitation guidelines of the European Resuscitation Council (ERC) support immediate angiography/PCI or fibrinolysis in these patients in order to improve survival.

Methods

Consecutive data on 1650 STEMI patients, transferred for primary PCI in hospital STEMI networks between November 2005 and January 2007 from 7 countries in Europe were gathered. Patients were divided into two groups: OHCA group – 42 patients and no OHCA group – 1608 patients.

Results

Baseline demographics, clinical characteristic on admission to cathlab and past medical history were similar in both groups. Cardiogenic shock on admission or acute heart failure defined as Killip 3 + 4 was more frequently observed in OHCA group. The in-hospital mortality was similar, however, 1-year mortality was 19.1% in the OHCA group vs 8.1% in no OHCA group (p = 0.011) and remained significant after exclusion of patients in cardiogenic shock on admission.

Conclusions

STEMI patients treated with primary PCI with out-of-hospital cardiac arrest have higher long-term mortality than no OHCA patients. However, resuscitation prior to cathlab admission is not an independent predictor of long-term adverse outcome. No differences in in-hospital mortality were noticed.     

Novel adhesive glove device (AGD) for active compression-decompression (ACD) CPR results in improved carotid blood flow and coronary perfusion pressure in piglet model of cardiac arrest

Objective

ACD-CPR improves coronary and cerebral perfusion. We developed an adhesive glove device (AGD) and hypothesized that ACD-CPR using an AGD provides better chest decompression resulting in improved carotid blood flow as compared to standard (S)-CPR.

Design

Prospective, randomized and controlled animal study.

Methods

Sixteen anesthetized and ventilated piglets were randomized after 3 min of untreated VF to receive either S-CPR or AGD-ACD-CPR by a PALS certified single rescuer with compressions of 100 min⁻¹ and C:V ratio of 30:2. AGD consisted of a modified leather glove exposing the fingers and thumb. A wide Velcro patch was sewn to the palmer aspect of the glove and the counter Velcro patch was adhered to the pig's chest wall. Carotid blood flow was measured using ultrasound. Data (mean ± SD) was analyzed using one way ANOVA and unpaired t-test; p-value ≤ 0.05 was considered statistically significant.

Results

Right atrial pressure (mm Hg) during the decompression phase was lower during AGD-ACD-CPR (−3.32 ± 2.0) when compared to S-CPR (0.86 ± 1.8, p = 0.0007). Mean carotid blood flow was 53.2 ± 27.1 (% of baseline blood flow in ml/min) in AGD vs. 19.1 ± 12.5% in S-CPR, p = 0.006. Coronary perfusion pressure (CPP, mm Hg) was 29.9 ± 5.8 in AGD vs. 22.7 ± 6.9 in S-CPR, p = 0.04. There was no significant difference in time to ROSC and number of epinephrine doses.

Conclusion

Active chest decompression during CPR using this simple and inexpensive adhesive glove device resulted in significantly better carotid blood flow during the first 2 min of CPR.     

Comparison of different video laryngoscopes for emergency intubation in a standardized airway manikin with immobilized cervical spine by experienced anaesthetists. A randomized, controlled crossover trial

Background

The aim of the present study was to evaluate whether different video laryngoscopes (VLs) facilitate endotracheal intubation (ETI) faster or more secure than conventional laryngoscopy in a manikin with immobilized cervical spine.

Methods

After local ethics board approval, a standard airway manikin with cervical spine immobilization by means of a standard stiff collar was placed on a trauma stretcher. We compared times until glottic view, ETI, cuff block and first ventilation were achieved, and verified the endotracheal tube position, when using Macintosh laryngoscope, Glidescope Ranger, Storz C-MAC, Ambu Pentax AWS, Airtraq, and McGrath Series5 VLs in randomized order. Wilcoxon signed-rank test and McNemar's test were used for statistical analysis; p < 0.05 was considered as significant.

Results

Twenty-three anaesthetists (mean age 32.1 ± 4.9 years, mean experience in anaesthesia of 6.9 ± 4.8 years) routinely involved in the management of multitrauma patients participated. The primary study end point, time to first effective ventilation, was achieved fastest when using Macintosh laryngoscope (21.0 ± 7.6 s) and was significantly slower with all other devices (Airtraq 33.2 ± 23.9 s, p = 0.002; Pentax AirwayScope 32.4 ± 14.9 s, p = 0.001; Storz C-MAC 34.1 ± 23.9 s, p < 0.001; McGrath Series5 101.7 ± 108.3 s, p < 0.001; Glidescope Ranger 46.3 ± 59.1 s, p = 0.001). Overall success rates were highest when using Macintosh, Airtraq and Storz C-MAC devices (100%), and were lower in Ambu Pentax AWS and Glidescope Ranger (87%, p = 0.5) and in McGrath Series5 device (72.2%, p = 0.063).

Conclusion

When used by experienced anaesthesiologists, video laryngoscopes did not facilitate endotracheal intubation in this model with an immobilized cervical spine in a faster or more secure way than conventional laryngoscopy. However, data was gathered in a standardized model and further studies in real trauma patients are desirable to verify our findings.     

Eleven years of experience with extracorporeal cardiopulmonary resuscitation for paediatric patients with in-hospital cardiac arrest

Purpose

The study aims to describe 11 years of experience with extracorporeal cardiopulmonary resuscitation (ECPR) for in-hospital paediatric cardiac arrest in a university affiliated tertiary care hospital.

Methods

Paediatric patients who received extracorporeal membrane oxygenation (ECMO) during active extracorporeal cardiopulmonary resuscitation (ECPR) at our centre from 1999 to 2009 were included in this retrospective study. The results from three different cohorts (1999–2001, 2002–2005 and 2006–2009) were compared. Survival rates and neurological outcomes were analysed. Favourable neurological outcome was defined as paediatric cerebral performance categories (PCPC) 1, 2 and 3.

Results

We identified 54 ECPR events. The survival rate to hospital discharge was 46% (25/54), and 21 (84%) of the survivors had favourable neurological outcomes.The duration of CPR was 39 ± 17 min in the survivors and 52 ± 45 min in the non-survivors (p = NS). The patients with pure cardiac causes of cardiac arrest had a survival rate similar to patients with non-cardiac causes (47% (18/38) vs. 44% (7/16), p = NS).The non-survivors had higher serum lactate levels prior to ECPR (13.4 ± 6.4 vs. 8.8 ± 5.1 mmol/L, p < 0.01) and more renal failure after ECPR (66% (19/29) vs. 20% (5/25), p < 0.01).The patients resuscitated between 2006 and 2009 had shorter durations of CPR (34 ± 13 vs. 78 ± 76 min, p = 0.032) and higher rates of survival (55% (16/29) vs. 0% (0/8), p = 0.017) than those resuscitated between 1999 and 2002.

Conclusions

In our single-centre experience with ECPR for paediatric in-hospital cardiac arrest, the duration of CPR has become shorter and outcomes have improved in recent years. Higher pre-ECPR lactate levels and the presence of post-ECPR renal failure were associated with increased mortality. The presence of non-cardiac causes of cardiac arrest did not preclude successful ECPR outcomes. The duration of CPR was not significantly associated with poor outcomes in this study.     

Rescuer fatigue during actual in-hospital cardiopulmonary resuscitation with audiovisual feedback: A prospective multicenter study

Background

Rescuer fatigue during cardiopulmonary resuscitation (CPR) is a likely contributor to variable CPR quality during clinical resuscitation efforts, yet investigations into fatigue and CPR quality degradation have only been performed in simulated environments, with widely conflicting results.

Objective

We sought to characterize CPR quality decay during actual in-hospital cardiac arrest, with regard to both chest compression (CC) rate and depth during the delivery of CCs by individual rescuers over time.

Methods

Using CPR recording technology to objectively quantify CCs and provide audiovisual feedback, we prospectively collected CPR performance data from arrest events in two hospitals. We identified continuous CPR “blocks” from individual rescuers, assessing CC rate and depth over time.

Results

135 blocks of continuous CPR were identified from 42 cardiac arrests at the two institutions. Median duration of continuous CPR blocks was 112 s (IQR 101–122). CC rate did not change significantly over single rescuer performance, with an initial mean rate of 105 ± 11/min, and a mean rate after 3 min of 106 ± 9/min (p = NS). However, CC depth decayed significantly between 90 s and 2 min, falling from a mean of 48.3 ± 9.6 mm to 46.0 ± 9.0 mm (p = 0.0006) and to 43.7 ± 7.4 mm by 3 min (p = 0.002).

Conclusions

During actual in-hospital CPR with audiovisual feedback, CC depth decay became evident after 90 s of CPR, but CC rate did not change. These data provide clinical evidence for rescuer fatigue during actual resuscitations and support current guideline recommendations to rotate rescuers during CC delivery.     

Comparison of manually triggered ventilation and bag-valve-mask ventilation during cardiopulmonary resuscitation in a manikin model

Background

To compare a novel, pressure-limited, flow adaptive ventilator that enables manual triggering of ventilations (MEDUMAT Easy CPR, Weinmann, Germany) with a bag-valve-mask (BVM) device during simulated cardiac arrest.

Methods

Overall 74 third-year medical students received brief video instructions (BVM: 57 s, ventilator: 126 s), standardised theoretical instructions and practical training for both devices. Four days later, the students were randomised into 37 two-rescuer teams and were asked to perform 8 min of cardiopulmonary resuscitation (CPR) on a manikin using either the ventilator or the BVM (randomisation list). Applied tidal volumes (V_T), inspiratory times and hands-off times were recorded. Maximum airway pressures (P_max) were measured with a sensor connected to the artificial lung. Questionnaires concerning levels of fatigue, stress and handling were evaluated. V_T, pressures and hands-off times were compared using t-tests, questionnaire data were analysed using the Wilcoxon test.

Results

BVM vs. ventilator (mean ± SD): the mean V_T (408 ± 164 ml vs. 315 ± 165 ml, p = 0.10) and the maximum V_T did not differ, but the number of recorded V_T < 200 ml differed (8.1 ± 11.3 vs. 17.0 ± 14.4 ventilations, p = 0.04). P_max did not differ, but inspiratory times (0.80 ± 0.23 s vs. 1.39 ± 0.31 s, p < 0.001) and total hands-off times (133.5 ± 17.8 s vs. 162.0 ± 11.1 s, p < 0.001) did. The estimated levels of fatigue and stress were comparable; however, the BVM was rated to be easier to use (p = 0.03).

Conclusion

For the user group investigated here, this ventilator exhibits no advantages in the setting of simulated CPR and carries a risk of prolonged no-flow time.     

Comparison of relative and actual chest compression depths during cardiac arrest in children, adolescents, and young adults

Aim

Cardiopulmonary resuscitation (CPR) guidelines recommend specific chest compression (CC) target depths for children. We quantitatively describe relative anterior–posterior diameter (APD) depth, actual depth, and force of CCs during real CPR events in children.

Methods

CC depth and force were recorded during real CPR events in children ≥8 years using FDA-approved CC sensor. Patient chest APD was measured at conclusion of each CPR event. CC data was stratified and analyzed according to age (pre-puberty, 8–14 years; post-puberty, 15+ years). Relative (% APD) and actual CC depth, corrected for mattress deflection, were assessed and compared with American Heart Association (AHA) 2005 and 2010 pediatric CPR guidelines.

Results

35 events in 32 subjects included 16,158 CCs for data analysis: 16 pre-puberty (CCs = 7484, age 11.9 ± 2 years, APD 164.6 ± 25.1 mm); 19 post-puberty (CCs = 8674, age 18.0 ± 2.7 years, APD 196.5 ± 30.4 mm). After correction for mattress deflection, 92% of CC delivered to pre-puberty were <1/3 relative APD and 60% of CC were <38 mm actual depth. Mean actual CC depth (36.2 ± 9.6 mm vs. 36.8 ± 9.9 mm, p = 0.64), mean relative APD (22.5% ± 7.0% vs. 19.5 ± 6.7%, p = 0.13), and mean CC force (30.7 ± 7.6 kg vs. 33.6 ± 9.4 kg, p = 0.07) were not significantly less in pre-puberty vs. post-puberty.

Conclusions

During in-hospital cardiac arrest of children ≥8 years, CCs delivered by resuscitation teams were frequently <1/3 relative APD and <38 mm actual depth after mattress deflection correction, below pediatric and adult target guidelines. Mean CC actual depth and force were not significantly different in pre-puberty and post-puberty. Additional investigation to determine depth of CCs to optimize hemodynamics and outcomes is needed to inform future CPR guidelines.     

Randomised study of hypertonic saline infusion during resuscitation from out-of-hospital cardiac arrest

Aim of the study

Animal models of hypertonic saline infusion during cardiopulmonary resuscitation (CPR) improve survival, as well as myocardial and cerebral perfusion during CPR. We studied the effect of hypertonic saline infusion during CPR (Guidelines 2000) on survival to hospital admission and hospital discharge, and neurological outcome on hospital discharge.

Methods

The study was performed by the EMS of Bonn, Germany, with ethical committee approval. Study inclusion criteria were non-traumatic out-of-hospital cardiac arrest, aged 18–80 years, and given of adrenaline (epinephrine) during CPR. Patients were randomly infused 2 ml kg⁻¹ HHS (7.2% NaCl with 6% hydroxyethyl starch 200,000/0.5 [HES]) or HES over 10 min.

Results

203 patients were randomised between May 2001 and June 2004. After HHS infusion, plasma sodium concentration increased significantly to 162 ± 36 mmol l⁻¹ at 10 min after infusion and decreased to near normal (144 ± 6 mmol l⁻¹) at hospital admission. Survival to hospital admission and hospital discharge was similar in both groups (50/100 HHS vs. 49/103 HES for hospital admission, 23/100 HHS vs. 22/103 HES for hospital discharge). There was a small improvement in neurological outcome in survivors on discharge (cerebral performance category 1 or 2) in the HHS group compared to the HES group (13/100 HHS vs. 5/100 HES, p < 0.05, odds-ratio 2.9, 95% confidence interval 1.004–8.5).

Conclusion

Hypertonic saline infusion during CPR using Guidelines 2000 did not improve survival to hospital admission or hospital discharge. There was a small improvement with hypertonic saline in the secondary endpoint of neurological outcome on discharge in survivors. Further adequately powered studies using current guidelines are needed.     

The prognosis of patients with dissociated virological and immunological responses to HAART

Background

While HAART allows for the reconstitution of immune functions in most treated HIV patients, failure to achieve a significant increase in circulating CD4+ T cells despite undetectable viremia occurs.

Methods

A retrospective study was conducted to evaluate the treatment outcome in a subgroup of 232 patients who after 3.1 years of treatment had not achieved desirable immune reconstitution despite a good virological response to HAART.

Results

After a further 3.6 ± 2.4 years of HAART, 82 (35.3%) patients achieved immune reconstitution (565.2 ± 174.6 CD4 cells/μl), while 149 (64.2%) patients did not (268.8 ± 91.1 cells/μl); the difference in the achieved CD4 counts between these subgroups was significant (P < 0.01). One patient experienced treatment failure. Eleven patients died to the end of follow-up, of which 10 with a continuously dissociated response. Factors associated with immune recovery included clinical AIDS at HAART initiation (OR: 0.4, 95% CI: 0.24–0.81, P < 0.01), usage of PIs and of drugs from all three classes (OR: 1.7, 95% CI: 1.0–3.0, P = 0.046 and OR: 4.5, 95% CI: 1.15–18.19, P = 0.03, respectively), and a rise in CD4 count to over 200 cells/μl after the first 3.1 years of treatment (OR: 5.3 95% CI: 2.6–11.0, P < 0.01). Achievement of a rise in CD4 count to over 200 cells/μl after the first 3.1 years of treatment was an independent predictor of immune reconstitution in the following period.

Conclusion

If patients on HAART reach CD4 cell counts of above 200 cells/μl in the first 3 years, immune recovery is possible after at least 6 years of treatment.     

Cardiovascular and microvascular responses to mild hypothermia in an ovine model

Aims

Hypothermia is used for brain protection after resuscitation from cardiac arrest and other forms of brain injury, but its impact on systemic and tissue perfusion has not been well defined. The aim of this study was to evaluate the cardiovascular and microvascular responses to mild therapeutic hypothermia (MTH) in an ovine model.

Methods

Seven anaesthetised, mechanically ventilated, invasively monitored sheep were cooled from a baseline temperature of 39–40 °C to 34 °C using cold intravenous fluids, ice packs and transnasal cooling. After 6 h of MTH, sheep were progressively re-warmed to baseline temperature. Positive fluid balance was maintained during the entire study period to avoid hypovolemia. In addition to standard haemodynamic assessment, the sublingual microcirculation was evaluated using sidestream dark-field (SDF) videomicroscopy.

Results

MTH was associated with significant decreases in cardiac index and left (LVSWI) and right (RVSWI) ventricular stroke work indexes. There was a downward shift in the relationship between LVSWI and pulmonary artery occlusion pressure during MTH, indicating myocardial depression. During MTH, mixed venous oxygen saturation increased, in association with reduced oxygen consumption, but blood lactate concentrations increased significantly. There was a significant decrease in the proportion and density of small perfused vessels. All variables returned to baseline levels during the re-warming phase.

Conclusion

In this large animal model, MTH was associated with decreased ventricular function, oxygen extraction and microvascular flow compared to normothermia. These changes were associated with increased blood lactate levels. These observations suggest that MTH may impair tissue oxygen delivery through maldistribution of capillary flow.     

The beneficial effect of mild therapeutic hypothermia depends on the time of complete circulatory standstill in patients with cardiac arrest

Aim

Mild therapeutic hypothermia has shown to improve long-time survival as well as favorable functional outcome after cardiac arrest. Animal models suggest that ischemic durations beyond 8 min results in progressively worse neurologic deficits. Based on these considerations, it would be obvious that cardiac arrest survivors would benefit most from mild therapeutic hypothermia if they have reached a complete circulatory standstill of more than 8 min.

Methods

In this retrospective cohort study we included cardiac arrest survivors of 18 years of age or older suffering a witnessed out-of-hospital cardiac arrest, which remain comatose after restoration of spontaneous circulation. Data were collected from 1992 to 2010. We investigated the interaction of ‘no-flow’ time on the association between post arrest mild therapeutic hypothermia and good neurological outcome. ‘No-flow’ time was categorized into time quartiles (0, 1–2, 3–8, >8 min).

Results

One thousand-two-hundred patients were analyzed. Hypothermia was induced in 598 patients. In spite of showing a statistically significant improvement in favorable neurologic outcome in all patients treated with mild therapeutic hypothermia (odds ratio [OR]: 1.49; 95% confidence interval [CI]: 1.14–1.93) this effect varies with ‘no-flow’ time. The effect is significant in patients with ‘no-flow’ times of more than 2 min (OR: 2.72; CI: 1.35–5.48) with the maximum benefit in those with ‘no-flow’ times beyond 8 min (OR: 6.15; CI: 2.23–16.99).

Conclusion

The beneficial effect of mild therapeutic hypothermia increases with cumulative time of complete circulatory standstill in patients with witnessed out-of-hospital cardiac arrest.     

Effects of continuous haemofiltration on serum enzyme concentrations, endotoxemia, homeostasis and survival in dogs with severe heat stroke

Aim

To examine the effectiveness of continuous haemofiltration as a treatment for severe heat stroke in dogs.

Methods

Dogs were randomly allocated to a control or continuous haemofiltration group (both n = 8). Heat stroke was induced by placing anaesthetised dogs in a high temperature cabin simulator. Upon confirmation of heat stroke (rectal temperature > 42 °C, mean arterial pressure (MAP) decrease > 25 mmHg), dogs were removed from the chamber and continuous haemofiltration was initiated and continued for 3 h for dogs in the continuous haemofiltration group. Dogs in the control group were observed at room temperature.

Results

Rectal temperature, haemodynamics, pH, blood gases and electrolyte concentrations rapidly returned to baseline in the continuous haemofiltration group, but not the control group. After 3 h, rectal temperature was 36.68 ± 0.51 °C in the continuous haemofiltration group and 39.83 ± 1.10 °C in the control group (P < 0.05). Continuous haemofiltration prevented endotoxin and all serum enzyme concentrations from increasing and caused malondialdehyde concentrations to decrease. After 3 h, endotoxin concentrations were 0.14 ± 0.02 EU ml⁻¹ in the continuous haemofiltration group and 0.23 ± 0.05 EU ml⁻¹ in the control group (P = 0.003), while malondialdehyde concentrations were 4.86 ± 0.61 mmol l⁻¹ in the continuous haemofiltration group and 8.63 ± 0.66 mmol l⁻¹ in the control group (P < 0.001). Five dogs died in the control group within 3 h, whereas no dogs died in the continuous haemofiltration group.

Conclusions

Continuous haemofiltration rapidly reduced body temperature, normalised haemodynamics and electrolytes, improved serum enzyme concentrations and increased survival in dogs with heat stroke. Continuous haemofiltration may be an effective treatment for heat stroke.     

The impact of a step stool on cardiopulmonary resuscitation: a cross-over mannequin study

Objective

Shallow chest compressions and incomplete recoil are common during cardiopulmonary resuscitation (CPR) and negatively affect outcomes. A step stool has the potential to alter these parameters when performing CPR in a bed but the impact has not been quantified.

Methods

We conducted a cross-over design, simulated study of in-hospital cardiac arrest. Rescuers performed a total of four 2-min segments of uninterrupted chest compressions, half of which were on a step stool. Compression characteristics were measured using a CPR-sensing defibrillator and subjective impressions were obtained from rescuer surveys. Paired analyses were performed to measure the impact of the step stool, taking into account rescuer characteristics, including height.

Results

Fifty subjects, of whom 36% were men, with a median height of 169.8 cm (range 148.6–190.5) volunteered to participate. Use of a step stool resulted in an average increase in compression depth of 4 mm (p < 0.001) and 18% increase in incomplete recoil (p < 0.001). However, unlike with incomplete recoil, the effect was more pronounced in rescuers in the lowest height tertile (9 ± 9 mm vs 2 ± 6 mm for those rescuers taller than 167 cm, p = 0.006).

Conclusions

Using a step stool when performing CPR in a bed results in a trade-off between increased compression depth and increased incomplete recoil. Given the nonlinear relationship between the increase in compression depth and rescuer height, the benefit of a step stool may outweigh the risks of incomplete release for rescuers ≤167 cm in height. The benefit is less clear in taller rescuers.     

Hemostasis in cardiac arrest patients treated with mild hypothermia initiated by cold fluids

Aim of the study

Application of mild hypothermia (32–33 °C) has been shown to improve neurological outcome in patients with cardiac arrest. However, hypothermia affects hemostasis, and even mild hypothermia is associated with bleeding and increased transfusion requirements in surgery patients. On the other hand, crystalloid hemodilution has been shown to induce a hypercoagulable state. The study aim was to elucidate in which way the induction of mild therapeutic hypothermia by a bolus infusion of cold crystalloids affects the coagulation system of patients with cardiac arrest.

Methods

This was a prospective pilot study in 18 patients with cardiac arrest and return of spontaneous circulation (ROSC). Mild hypothermia was initiated by a bolus infusion of cold 0.9% saline fluid (4 °C; 30 ml/kg/30 min) and maintained for 24 h. At 0 h (before hypothermia), 1, 6 and 24 h we assessed coagulation parameters (PT, APPT), platelet count and performed thrombelastography (ROTEM) after in vitro addition of heparinase.

Results

A total amount of 2528 (±528) ml of 0.9% saline fluid was given. Hematocrit (p < 0.01) and platelet count (−27%; p < 0.05) declined, whereas APTT increased (2.7-fold; p < 0.01) during the observation period. All ROTEM parameters besides clotting time (CT) after 1 h (−20%; p < 0.05) did not significantly change.

Conclusion

Mild hypothermia only slightly prolonged clotting time as measured by rotation thrombelastography. Therefore, therapeutic hypothermia initiated by cold crystalloid fluids has only minor overall effects on coagulation in patients with cardiac arrest.     

Comparison of defibrillation efficacy between two pads placements in a pediatric porcine model of cardiac arrest

Objective

The placement of defibrillation pads at ideal anatomical sites is one of the major determinants of transthoracic defibrillation success. However, the optimal pads position for ventricular defibrillation is still undetermined. In the present study, we compared the effects of two different pads positions on defibrillation success rate in a pediatric porcine model of cardiac arrest.

Methods

Eight domestic male pigs weighing 12–15 kg were randomized to receive shocks using either the anterior–posterior (AP) or the anterior–lateral (AL) position with pediatric pads. Ventricular fibrillation (VF) was electrically induced and untreated for 30 s. A sequence of randomized biphasic electrical shocks ranging from 10 to 100 J was attempted. If the defibrillation failed to terminate VF, a 100 J rescuer shock was then delivered. After a recovery interval of 5 min, the sequence was repeated for a total of approximately 30 test shocks were attempted for each animal. The dose response curves were constructed and the defibrillation thresholds were compared between groups.

Results

The aggregated success rate was 65.6% for AP placement and 43.0% for AL one (p = 0.0005) when shock energy was between 10 and 70 J. A significantly lower 50% defibrillation threshold was obtained for AP pads placement compared with traditional AL pads position (2.1 ± 0.4 J/kg vs. 3.6 ± 0.9 J/kg, p = 0.041).

Conclusion

In this pediatric porcine model of cardiac arrest, the anterior–posterior placement of pediatric pads yielded a higher success rate by lowering defibrillation threshold compared to the anterior–lateral position.