Hyoung Youn Lee

Association between mean arterial blood gas tension and outcome in cardiac arrest patients treated with therapeutic hypothermia

BACKGROUND Studies investigating the relationship between blood gas tension and outcome in cardiac arrest survivors have reported conflicting results. This might have resulted from the use of a blood gas value at a single time point and the difference in the proportion of patients treated with therapeutic hypothermia (TH). We investigated the association of the mean blood gas tensions calculated from blood gas values obtained between restoration of spontaneous circulation and end of TH with the outcome in cardiac arrest patients treated with TH. METHODS This was a retrospective observational study including 213 adult cardiac arrest patients. The cohort was divided into four categories based on the distribution of the mean Pao2 data using quartiles as cut-off values between categories. According to the mean Paco2, the cohort was divided into hypocarbia, normocarbia, and hypercarbia. The primary outcome was in-hospital mortality. RESULTS In multivariate analysis, the mean Pao2 quartile was not associated with in-hospital mortality, but hypocarbia was significantly associated with increased risk of in-hospital mortality (odds ratio 2.522; 95% confidence interval 1.184-5.372; P = .016). We found a V-shaped independent association between the mean Pao2 and poor neurologic outcome at hospital discharge, with the risk of poor neurologic outcome increasing with a descending and ascending Pao2 ranges. CONCLUSION Mean Pao2 had no independent association with in-hospital mortality whereas hypocarbia was independently associated with in-hospital mortality. We also found a V-shaped independent association between the mean Pao2 and poor neurologic outcome at hospital discharge.

Combining brain computed tomography and serum neuron specific enolase improves the prognostic performance compared to either alone in comatose cardiac arrest survivors treated with therapeutic hypothermia.

AIM OF THE STUDY We determined whether combining the grey-to-white matter ratio (GWR) on brain computed tomography (CT) and serum neuron specific enolase (NSE) improves the prognostic performance when compared to either alone in cardiac arrest patients treated with therapeutic hypothermia (TH). METHODS We performed a retrospective study of a cohort of cardiac arrest patients treated with TH. The Hounsfield unit was measured in the caudate nucleus (CN), putamen (P), posterior limb of internal capsule (PIC) and corpus callosum (CC); GWR was calculated as CN/PIC and P/CC. The NSE value was obtained at 0, 24, and 48h after restoration of spontaneous circulation (ROSC). We analysed the prognostic performance of GWR and NSE, singly and in combination, in predicting poor neurologic outcome (cerebral performance category 3-5). RESULTS Of the 224 included patients, 82 showed good neurologic outcome at hospital discharge, while 142 showed poor neurologic outcome. The P/CC (area under receiver operating characteristics (AUROC) 0.864, sensitivity/specificity 52.9%/100%) showed better prognostic performance than did the CN/PIC (AUROC 0.721, sensitivity/specificity 19.8%/100%). The NSE value at 48h after ROSC (AUROC 0.895, sensitivity/specificity 60.2%/100%) showed the highest prognostic value among the three NSE time points. Analysis of 119 patients undergoing both brain CT and NSE at 48h indicated that combining P/CC and NSE improved the sensitivity (78.6%) compared to either alone (48.6%, 62.9%). CONCLUSION Combining brain CT and serum NSE improves the prognostic performance when compared to either alone in predicting poor neurologic outcome in cardiac arrest patients treated with TH.

Outcomes of therapeutic hypothermia in unconscious patients after near-hanging

Background Hanging has been increasingly used to commit suicide. There is no specific treatment besides general intensive care after near-hanging. Therapeutic hypothermia (TH) has been used in unconscious patients after near-hanging. Objective To describe the outcomes in unconscious patients after near-hanging in order to determine whether TH improves the outcome of near-hanging injury. Methods Medical charts were reviewed of unconscious patients after near-hanging who presented to Chonnam National University Hospital between January 2006 and December 2010 and who were considered to be eligible for TH. According to local policy, unconscious survivors after near-hanging, whether or not they experienced cardiac arrest at the scene, were treated with TH if this was agreed by next-of-kin. Results There were 16 survivors of asphyxial cardiac arrest after near-hanging, of whom 13 received TH. Among them, only one (7.7%, 95% CI 1.4% to 33.3%) attained Cerebral Performance Category (CPC) 1; the other 15 patients had poor neurological outcomes (CPC 5 in seven patients and CPC 4 in eight patients). Nine of the patients did not experience cardiac arrest at the scene and of these, four received TH and five received normothermic treatment. All patients who did not have cardiac arrest recovered and were discharged with CPC 1. Conclusion In this study, outcomes in unconscious near-hanging patients with cardiac arrest were poor despite treatment with TH. Before recommending TH in near-hanging patients, a prospective, randomised controlled study is required.

Outcome and adverse events with 72-hour cooling at 32°C as compared to 24-hour cooling at 33°C in comatose asphyxial arrest survivors.

PURPOSE Studies suggest that the current therapeutic hypothermia (TH) protocol does not improve outcomes in adult asphyxial arrest survivors. We sought to compare the effect of 24-hour cooling at 33°C vs that of 72-hour cooling at 32°C on outcomes and the incidence of adverse events in unconscious asphyxial arrest survivors. METHODS Retrospectively collected data on 79 consecutive asphyxial arrest patients treated with TH from January 2006 to March 2013 were analyzed. Forty-one patients who presented between January 2006 and January 2011 formed the 33°C-24 h group, whereas 38 patients who presented between February 2011 and March 2013 formed the 32°C-72 h group. The primary outcome was neurologic outcome at 30 days following arrest. The secondary outcomes were all-cause mortality at 30 days following arrest and the incidence of adverse events. RESULTS The Kaplan-Meier curve showed no significant difference in survival over time during the 30 days after arrest between the 2 groups (P = .608). Good neurologic outcome was achieved in only 2 patients (2.5%) of the overall cohort, despite TH. One of the 32°C-72 h group (2.6%; 95% confidence interval, 4.7%-13.5%) had a good neurologic outcome, as did one of the 33°C-24 h group (2.4%; 95% confidence interval, 4.3%-12.6%) (P = 1.000). There were no significant differences in the rates of adverse events between the 2 groups. CONCLUSION The present study did not demonstrate an advantage of 72-hour cooling at 32°C in unconscious asphyxial arrest patients compared with 24-hour cooling at 33°C.

Variable effects of high-dose adrenaline relative to standard-dose adrenaline on resuscitation outcomes according to cardiac arrest duration.

AIM OF THE STUDY Adjustment of adrenaline (epinephrine) dosage according to cardiac arrest (CA) duration, rather than administering the same dose, may theoretically improve resuscitation outcomes. We evaluated variable effects of high-dose adrenaline (HDA) relative to standard-dose adrenaline (SDA) on resuscitation outcomes according to CA duration. METHODS Twenty-eight male domestic pigs were randomised to the following 4 groups according to the dosage of adrenaline (SDA 0.02 mg/kg vs. HDA 0.2mg/kg) and duration of CA before beginning cardiopulmonary resuscitation (CPR): 6 min SDA, 6 min HDA, 13 min SDA, or 13 min HDA. After the predetermined duration of untreated ventricular fibrillation, CPR was provided. RESULTS All animals in the 6 min SDA, 6 min HDA, and 13 min HDA groups were successfully resuscitated, while only 4 of 7 pigs in the 13 min SDA group were successfully resuscitated (p=0.043). HDA groups showed higher right atrial pressure, more frequent ventricular ectopic beats, higher blood glucose, higher troponin-I, and more severe metabolic acidosis than SDA groups. Animals of 13 min groups showed more severe metabolic acidosis and higher troponin-I than animals of 6 min groups. All successfully resuscitated animals, except two animals in the 13 min HDA group, survived for 7 days (p=0.121). Neurologic deficit score was not affected by the dose of adrenaline. CONCLUSION HDA showed benefit in achieving restoration of spontaneous circulation in 13 min CA, when compared with 6 min CA. However, this benefit did not translate into improved long-term survival or neurologic outcome.

Mortality rate and pattern following carbamate methomyl poisoning. Comparison with organophosphate poisoning of comparable toxicity.

Context. Methomyl is a widely used carbamate insecticide. It is known that mortality rate is generally low in carbamate poisoning, but fatalities from methomyl poisoning have been reported. Nevertheless, there is no reported comparative outcome of methomyl and organophosphate poisoning of comparable toxicity concerning mortality rate and mortality pattern. Objective. This study aims to compare the mortality rate and pattern following methomyl poisoning with those after organophosphate poisoning of comparable toxicity. Material and methods. A retrospective study was conducted on patients with cholinesterase inhibitor poisoning admitted to our institution. Among a diverse group of cholinesterase inhibitors, we included patients who presented after ingesting methomyl or World Health Organisation hazard Class I organophosphate compounds. Patients were divided into two groups; the methomyl group and the Class I organophosphate group. Results. The methomyl group consisted of 17 patients, and the Class I organophosphate group consisted of 42 patients. Seven patients (41.2%) in the methomyl group presented with cardiac arrest, while none presented with cardiac arrest in the Class I organophosphate group (p < 0.001). In the methomyl group, patients who had not experienced cardiac arrest at presentation survived to discharge from hospital. Among the seven patients who presented with cardiac arrest, three died from multiple organ dysfunction syndrome after resuscitation from cardiac arrest. In the Class I organophosphate group, four patients died from pneumonia and complicating acute respiratory distress syndrome. Therefore, the mortality rate was 17.6% in the methomyl group and 9.5% in the Class I organophosphate group (p = 0.399). Conclusion. The mortality rate of methomyl poisoning was comparable to that of World Health Organisation Class I organophosphate poisoning. All died patients in the methomyl group experienced cardiac arrest, and died from multiple organ dysfunction syndrome after resuscitation from cardiac arrest.

The Performances of Standard and ResMed Masks During Bag–Valve–Mask Ventilation

Abstract Background. A tight mask seal is frequently difficult to obtain and maintain during single-rescuer bag–valve–mask (BVM) ventilation. The ResMed mask (Bella Vista, NSW, Australia) is a continuous-positive-airway-pressure mask (CM) designed for noninvasive ventilation. Objective. In this study, we compared the ventilation performances of a standard mask (SM) and a ResMed CM using a simulation manikin in an out-of-hospital single-rescuer BVM ventilation scenario. Methods. Thirty emergency medical technicians (EMTs) performed two 2-minute attempts to ventilate a simulation manikin using BVM ventilation, alternatively, with the SM or the ResMed CM in a randomized order. Ventilation parameters including tidal volume and peak airway pressure were measured using computer analysis software connected to the simulation manikin. Successful volume delivery was defined as delivery of 440–540 mL of tidal volume in accord with present cardiopulmonary resuscitation guidelines. Results. BVM ventilation using the ResMed CM produced higher mean (± standard deviation) tidal volumes (452 ± 50 mL vs. 394 ± 113 mL, p = 0.014) and had a higher proportion of successful volume deliveries (65.3% vs. 26.7%, p < 0.001) than that using the SM. Peak airway pressure was higher in BVM ventilation using the ResMed CM (p = 0.035). Stomach insufflation did not occur during either method. Twenty-nine of the participants (96.7%) preferred BVM ventilation using the ResMed CM. Conclusions. BVM ventilations using ResMed CM resulted in a significantly higher proportion of successful volume deliveries meeting the currently recommended range of tidal volume. Clinical studies are needed to determine the value of the ResMed CM for BVM ventilation.

Association of blood glucose variability with outcomes in comatose cardiac arrest survivors treated with therapeutic hypothermia.

PURPOSE A recent study showed that increased blood glucose variability was an independent predictor of mortality in cardiac arrest survivors treated with therapeutic hypothermia (TH). We hypothesized that the association of blood glucose variability with outcomes would differ depending on the TH phase, as body temperature affects glucose homeostasis. METHODS A retrospective cohort of 147 consecutive cardiac arrest patients treated with TH was analyzed. Mean absolute glucose change (MAGC) was calculated using blood glucose values during the entire TH period and during each TH phase (induction, from the TH initiation to the achievement of the target temperature; maintenance, 24 hours from the end of induction; and rewarming, from the end of the maintenance to the achievement of 36.5°C). The primary and secondary outcomes were mortality and neurological outcome at 30 days. Multivariate regression analyses were performed with variables with a significance level <0.1 on univariate analyses. RESULTS The hypoglycemia rate increased significantly during the rewarming phase compared with the maintenance phase (P = .003). The MAGC during the TH maintenance phase was an independent predictor of mortality (OR = 1.056, 95% CI 1.008-1.107, P = .023) and unfavorable neurologic outcome (OR = 1.202, 95% CI 1.043-1.384, P = .038), while the MAGC during the rewarming phase and the entire TH period were not. CONCLUSION The increased MAGC during the TH maintenance phase was associated with mortality and unfavorable neurologic outcome. However, this study cannot prove a causal association due to the retrospective design. In addition, we showed that the hypoglycemia rate increased significantly during the rewarming phase.

Potassium induced cardiac standstill during conventional cardiopulmonary resuscitation in a pig model of prolonged ventricular fibrillation cardiac arrest: A feasibility study

AIM OF THE STUDY Potassium-based cardioplegia has been the gold standard for cardioprotection during cardiac surgery. We sought to evaluate the feasibility and the effects of potassium-induced cardiac standstill during conventional cardiopulmonary resuscitation (CPR) in a pig model of prolonged ventricular fibrillation (VF). METHODS VF was induced in 20 pigs, and circulatory arrest was maintained for 14 min. Animals were then resuscitated by standard CPR. Coincident with the start of CPR, 20 ml of saline (control group) or 0.9 mequiv.kg(-1) of potassium chloride diluted to 20 ml (potassium group) was administered into right atrium. RESULTS Administration of potassium resulted in asystole lasting for 1.0 min (0.2) in the potassium group animals. VF reappeared in all but one animal, in which wide QRS complex bradycardia followed. Restoration of spontaneous circulation (ROSC) was attained in two animals (20%) in the control group and in seven animals (70%) in the potassium group (p=0.070). Resuscitated animals in the potassium group required fewer countershocks (3, 4 vs. 2 (1-2)), smaller doses of adrenaline (1.84, 1.84 vs. 0.94 (0.90-1.00)mg), and shorter duration of CPR (8, 10 vs. 4.0 (4.0-4.0)min) than did the control group. Potassium concentrations normalised rapidly after ROSC in both groups, and the potassium concentrations at 5 min (5.5, 6.6 vs. 6.8 (6.5-7.8)mequiv.l(-1)) and 4h (4.9, 5.4 vs. 5.9 (5.1-6.4)mequiv.l(-1)) after ROSC were similar in the both groups. CONCLUSION In a pig model of untreated VF cardiac arrest for 14 min, resuscitation with potassium-induced cardiac standstill during conventional CPR was found to be feasible.

Performance of an automated external defibrillator in a moving ambulance vehicle

AIM OF THE STUDY The available data suggest that automated external defibrillators (AED) can be safely used in vibration-like moving conditions such as rigid inflatable boats and aircraft environments. However, little literature exists examining their performance in a moving ambulance. The present study was undertaken to determine whether an AED is able to analyse the heart rhythm correctly during ambulance transport. METHODS An ambulance was driven on paved (20-100 km/h) and unpaved (10 km/h) roads. The performance of two AED devices (CU ER 2, CU Medical Systems Inc., Korea, and Heartstart MRx, Phillips, USA) was determined in a moving ambulance using manikins. Vibration intensity was measured simultaneously with a digital vibrometer. AED performance was then evaluated again on manikins and on a swine model under simulated vibration intensities (0.5-5m/s(2)) measured by the vibrometer in the previous phase of the investigation. RESULTS The vibration intensity increased with increasing speeds on paved roads (1.98+/-0.44 m/s(2) at 100 km/h). While driving on unpaved roads, it increased to 6.40+/-1.06 m/s(2). Both AED algorithms analysed the heart rhythm correctly under resting state. When tested on pigs, both algorithms showed substantially degraded performances, even at low vibration intensities of 0.5-1m/s(2), which corresponded to vibration intensities while driving on paved roads at 20-60 km/h. This study also showed that electrocardiograms generated on manikins were more resistant to motion artifacts than were the pig electrocardiograms. CONCLUSION Ambulance personnel should consider the possibility of misinterpretation by an AED when this device is used while transporting a patient.