Search

Aim: To determine the epidemiological characteristics, temporal trends and survival outcomes of OHCAs precipitated by chemical asphyxiation.Methods: We conducted a retrospective cohort analysis of OHCAs attended by paramedics in Queensland, Australia between 2011 and 2020. Patients were classified into two groups depending on the asphyxiating agent involved; simple (argon, carbon dioxide, helium, liquified petroleum gas, nitrogen) and systemic (carbon monoxide, cyanides, hydrogen sulfide, methemoglobin-inducing substances, smoke inhalation). Incidence rates, characteristics and outcomes were described for the entire cohort and independently for each group, with the groups then compared. Temporal trends of asphyxiant utilisation were also described.Results: During the study period, 50,669 OHCAs were attended, with 551 (1.1%) attributable to chemical asphyxiation. The incidence rate was 1.1 per 100,000 population with no significant temporal changes. Suspected suicide was the primary cause of exposure (-95.8%), with systemic asphyixants the dominant agent reported in comparison to simple agents (66.4% vs 33.6%). Over the 10-year period, events precipitated by carbon monoxide decreased by 26.2% (p for trend < 0.001), helium remained unchanged (p for trend = 0.302) and incidents involving nitrogen increased by 28.7% (p for trend < 0.001). Overall, 14.2% (78/551) of the study cohort received a resuscitation attempt by paramedics with 6.4% of these incidents witnessed and 2.6% involving patients presenting in a shockable rhythm. Survival rates were low, with 6.4% surviving the index event, and 1.3% surviving to hospital discharge with a normal neurocognitive function.Conclusion: OHCA precipitated by chemical asphyxiation is relatively infrequent and associated with poor survival outcomes. [ABSTRACT FROM AUTHOR]

Background: Survival from avalanche burial is dependent on time to extraction, breathing ability, air pocket oxygen content, and avoiding rebreathing of carbon dioxide (CO2). Mortality from asphyxia increases rapidly after burial. Rescue services often arrive too late. Our objective was to evaluate the physiological effects of providing personal air supply in a simulated avalanche scenario as a possible concept to delay asphyxia. We hypothesize that supplemental air toward victim's face into the air pocket will prolong the window of potential survival.Methods: A prospective randomized crossover experimental field study enrolled 20 healthy subjects in Hemsedal, Norway in March 2019. Subjects underwent in randomized order two sessions (receiving 2 litres per minute of air in front of mouth/nose into the air pocket or no air) in a simulated avalanche scenario with extensive monitoring serving as their own control.Results: A significant increase comparing Control vs Intervention were documented for minimum and maximum end-tidal CO2 (EtCO2), respiration rate, tidal volume, minute ventilation, heart rate, invasive arterial blood pressures, but lower peripheral and cerebral oximetry. Controls compared to Intervention group subjects had a lower study completion rate (26% vs 74%), and minutes in the air pocket before interruption (13.1 ± 8.1 vs 22.4 ± 5.6 vs), respectively.Conclusions: Participants subject to simulated avalanche burial can maintain physiologic parameters within normal levels for a significantly longer period if they receive supplemental air in front of their mouth/nose into the air pocket. This may extend the time for potential rescue and lead to increased survival. [ABSTRACT FROM AUTHOR]

Background: Current neonatal resuscitation guidelines recommend using 100% oxygen during chest compressions (CC), however the most effective oxygen concentration during cardiopulmonary resuscitation remains controversial.Aim: In term newborn piglets with asphyxia-induced cardiac arrest does 21% oxygen compared to 100% oxygen during resuscitation using CC during sustained inflation (SI; CC + SI) will have a reduced time to return of spontaneous circulation (ROSC).Intervention and Measurements: Twenty-two mixed breed piglets (1-3 days old, 1.7-2.4 kg), were obtained on the day of the experiment and anesthetized, intubated, instrumented, and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were resuscitated using CC + SI and randomized to 21% oxygen (n = 8) or 100% oxygen (n = 8). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.Main Results: Baseline parameters were similar between 21% and 100% oxygen groups. There was no difference in asphyxiation (duration and degree) between groups. Time to ROSC was similar between 21% and 100% oxygen groups: median (interquartile range - IQR) 80 (70-190)sec vs. 90 (70-324)sec, (p = 0.56). There was no significant difference in the rate of ROSC between 21% and 100% oxygen groups: 7/8 (88%) vs. 5/8 (63%), (p = 0.569). All piglets that achieved ROSC survived to four hours post-resuscitation. Hemodynamics and regional perfusion were not significantly different between groups.Conclusions: In term newborn piglets resuscitated by CC + SI, the use of 21% oxygen resulted in a similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen. [ABSTRACT FROM AUTHOR]

Aim: The primary purpose of an avalanche airbag is to prevent burial during an avalanche. Approximately twenty percent of avalanche victims deploying airbags become critically buried, however. One avalanche airbag actively deflates three minutes after deployment, potentially creating an air pocket. Our objective was to evaluate this air pocket and its potential to prevent asphyxiation.Methods: Twelve participants were fitted with an airbag and placed prone on the snow. Participants deployed the airbag and were buried in 1.5 m of snow for 60 min with vital signs including oxygen saturation (SpO2) and end-tidal CO2 (ETCO2) measured every minute. Participants completed a post-burial survey to determine head movement within the air pocket.Results: Eleven of the 12 participants (92%) completed 60 min of burial. Preburial baseline SpO2 measurements did not change significantly over burial time (P > 0.05). Preburial baseline ETCO2 measurements increased over the burial time (P < 0.02); only one ETCO2 value was outside of the normal ETCO2 range (35-45 mmHg). Participants reported they could move their head forward 11.2 cm (SD 4.8 cm) and backward 6.6 cm (SD 5.1 cm) with the majority of participants stated that they had enough head movement to separate the oral cavity from opposing snow if necessary. Visual examination during extrication revealed a well-defined air pocket in all burials.Conclusion: The avalanche airbag under study creates an air pocket that appears to delay asphyxia, which could allow extra time for rescue and improve overall survival of avalanche victims. [ABSTRACT FROM AUTHOR]

Objective: We previously demonstrated that sustained inflation (SI) during chest compression (CC) significantly reduces time to return of spontaneous circulation (ROSC) when compared to 3:1 compression:ventilation (C:V) ratio during neonatal resuscitation. However, the optimal length of SI during CC to improve ROSC and hemodynamic recovery in severely asphyxiated piglets is unknown.Aim: To examine if different lengths of SI will improve ROSC and hemodynamic recovery in severely asphyxiated piglets.Intervention and Measurements: Thirty newborn piglets (1-3 days) were anesthetized, intubated, instrumented and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were randomized into four groups: 3:1 C:V (n = 8), CC with an SI duration of either 20 s (CC+SI 20) (n = 8) or 60 s (CC+SI 60) (n = 8), and a sham group (n = 6). Cardiac function, carotid blood flow, cerebral and renal oxygenation as well as respiratory parameters were continuously recorded throughout the experiment.Main Results: When compared with 3:1 group, both CC+SI 20 and CC+SI 60 groups had significantly shorter ROSC time (p = 0.002). All three intervention groups had similar hemodynamic recovery by the end of 4 h observation period. There was no difference in lung injury markers among all experimental groups. However, when compared to the sham group, the concentrations of IL-6 (thalamus) and IL-6 + IL-8 (frontoparietal cortex) of the 3:1 C:V group were significantly higher, respectively.Conclusions: Even though relatively less animals achieved ROSC, CC during SI significantly improved ROSC time compared to 3:1 C:V in asphyxiated newborn piglets. However, there was no difference in ROSC characteristics and hemodynamic recovery between two CC+SI groups. [ABSTRACT FROM AUTHOR]

Background: Multiple randomized clinical trials have compared specific airway management strategies during ACLS with conflicting results. However, patients with refractory cardiac arrest died in almost all cases without the availability of extracorporeal cardiopulmonary resuscitation (ECPR). Our aim was to determine if endotracheal intubation (ETI) was associated with improved outcomes compared to supraglottic airways (SGA) in patients with refractory cardiac arrest presenting for ECPR., Methods: We retrospectively studied 420 consecutive adult patients with refractory out-of-hospital cardiac arrest due to shockable presenting rhythms presenting to the University of Minnesota ECPR program. We compared outcomes between patients receiving ETI (n = 179) and SGA (n = 204). The primary outcome was the pre-cannulation arterial PaO 2 upon arrival to the ECMO cannulation center. Secondary outcomes included neurologically favorable survival to hospital discharge and eligibility for VA-ECMO based upon resuscitation continuation criteria applied upon arrival to the ECMO cannulation center., Results: Patients receiving ETI had significantly higher median PaO 2 (71 vs. 58 mmHg, p = 0.001), lower median PaCO 2 (55 vs. 75 mmHg, p < 0.001), and higher median pH (7.03 vs. 6.93, p < 0.001) compared to those receiving SGA. Patients receiving ETI were also significantly more likely to meet VA-ECMO eligibility criteria (85% vs. 74%, p = 0.008). Of patients eligible for VA-ECMO, patients receiving ETI had significantly higher neurologically favorable survival compared to SGA (42% vs. 29%, p = 0.02)., Conclusions: ETI was associated with improved oxygenation and ventilation after prolonged CPR. This resulted in increased rate of candidacy for ECPR and increased neurologically favorable survival to discharge with ETI compared to SGA., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Aim: Post-cardiac arrest hypothermic-targeted temperature management (HTTM) improves outcomes in preclinical cardiac arrest studies. However, inadequate understanding of the mechanisms and therapeutic windows remains a barrier to optimization. We tested the hypothesis that combined intra- and post-cardiac arrest HTTM provides a synergistic outcome benefit compared to either strategy alone.Methods: Rats subjected to 8-min asphyxial cardiac arrest were block randomized to 4 treatment groups (n=12/group): NTTM) normothermic-targeted temperature management; 1-24 HTTM) HTTM initiated 1h post-ROSC and maintained for 24h; Intra-1 HTTM) HTTM initiated at CPR onset and maintained for 1h; and Intra-24 HTTM) HTTM initiated at CPR onset and maintained for 24h. HTTM was induced by nasopharyngeal cooling and maintained using an automated temperature regulation system. Target temperature range was 36.5-37.5°C for NTTM and 32.0-34.0°C for HTTM. Post-arrest neurologic function score (NFS) was measured daily, and rats surviving 72h were euthanized for histological analysis of neurodegeneration.Results: Target brain temperature was achieved 7.8±3.3min after initiating intra-arrest cooling. The survival rate was 42%, 50%, 50%, and 92% in the NTTM, 1-24 HTTM, Intra-1 HTTM, and Intra-24 HTTM groups, respectively (p<0.05, Intra-24 group vs. all other groups). The rate of survival with good neurologic function (NFS≥450) was 33% in the Intra-24 HTTM group vs. 0% in all other groups (mid p<0.05). Hippocampal CA1 sector neurodegeneration was significantly reduced in the Intra-24 HTTM group compared to all other groups (p<0.05).Conclusion: Combined intra- and post-cardiac arrest HTTM has greater outcome benefits than either strategy alone. [ABSTRACT FROM AUTHOR]

Aim: Despite the minimal evidence, neonatal resuscitation guidelines recommend using 100% oxygen when chest compressions (CC) are needed. Uninterrupted CC in adult cardiopulmonary resuscitation (CPR) may improve CPR hemodynamics. We aimed to examine 21% oxygen (air) vs. 100% oxygen in 3:1 CC:ventilation (C:V) CPR or continuous CC with asynchronous ventilation (CCaV) in asphyxiated newborn piglets following cardiac arrest.Methods: Piglets (1-3 days old) were progressively asphyxiated until cardiac arrest and randomized to 4 experimental groups (n=8 each): air and 3:1 C:V CPR, 100% oxygen and 3:1 C:V CPR, air and CCaV, or 100% oxygen and CCaV. Time to return of spontaneous circulation (ROSC), mortality, and clinical and biochemical parameters were compared between groups. We used echocardiography to measure left ventricular (LV) stroke volume at baseline, at 30min and 4h after ROSC. Left common carotid artery blood pressure was measured continuously.Results: Time to ROSC (heart rate ≥100min(-1)) ranged from 75 to 592s and mortality 50-75%, with no differences between groups. Resuscitation with air was associated with higher LV stroke volume after ROSC and less myocardial oxidative stress compared to 100% oxygen groups. CCaV was associated with lower mean arterial blood pressure after ROSC and higher myocardial lactate than those of 3:1 C:V CPR.Conclusion: In neonatal asphyxia-induced cardiac arrest, using air during CC may reduce myocardial oxidative stress and improve cardiac function compared to 100% oxygen. Although overall recovery may be similar, CCaV may impair tissue perfusion compared to 3:1 C:V CPR. [ABSTRACT FROM AUTHOR]

Aim: To calculate the first Austrian avalanche survival curve and update a Swiss survival curve to explore survival patterns in the Alps.Methods: Avalanche accidents occurring between 2005/06 and 2012/13 in Austria and Switzerland were collected. Completely buried victims (i.e. burial of the head and chest) in open terrain with known outcome (survived or not survived) were included in the analysis. Extrication and survival curves were calculated using the Turnbull algorithm, as in previous studies.Results: 633 of the 796 completely buried victims were included (Austria n=333, Switzerland n=300). Overall survival was 56% (Austria 59%; Switzerland 52%; p=0.065). Time to extrication was shorter in Austria for victims buried ≤60min (p<0.001). The survival curves were similar and showed a rapid initial drop in survival probability and a second drop to 25-28% survival probability after burial duration of ca. 35min, where an inflection point exists and the curve levels off. In a logistic regression analysis, both duration of burial and burial depth had an independent effect on survival. Victims with an air pocket were more likely to survive, especially if buried >15min.Conclusion: The survival curves resembled those previously published and support the idea that underlying survival patterns are reproducible. The results are in accordance with current recommendations for management of avalanche victims and serve as a reminder that expedient companion rescue within a few minutes is critical for survival. An air pocket was shown to be a positive prognostic factor for survival. [ABSTRACT FROM AUTHOR]

Aim: The American Heart Association (AHA) recommends monitoring invasive arterial diastolic blood pressure (DBP) and end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR) when available. In intensive care unit patients, both may be available to the rescuer. The objective of this study was to compare DBP vs. ETCO2 during CPR as predictors of cardiac arrest survival.Methods: In two models of cardiac arrest (primary ventricular fibrillation [VF] and asphyxia-associated VF), 3-month old swine received either standard AHA guideline-based CPR or patient-centric, BP-guided CPR. Mean values of DBP and ETCO2 in the final 2min before the first defibrillation attempt were compared using receiver operating characteristic curves (area under curve [AUC] analysis). The optimal DBP cut point to predict survival was derived and subsequently validated in two independent, randomly generated cohorts.Results: Of 60 animals, 37 (61.7%) survived to 45min. DBP was higher in survivors than in non-survivors (40.6±1.8mmHg vs. 25.9±2.4mmHg; p<0.001), while ETCO2 was not different (30.0±1.5mmHg vs. 32.5±1.8mmHg; p=0.30). By AUC analysis, DBP was superior to ETCO2 (0.82 vs. 0.60; p=0.025) in discriminating survivors from non-survivors. The optimal DBP cut point in the derivation cohort was 34.1mmHg. In the validation cohort, this cut point demonstrated a sensitivity of 0.78, specificity of 0.81, positive predictive value of 0.64, and negative predictive value of 0.89 for survival.Conclusions: In both primary and asphyxia-associated VF porcine models of cardiac arrest, DBP discriminates survivors from non-survivors better than ETCO2. Failure to attain a DBP >34mmHg during CPR is highly predictive of non-survival. [ABSTRACT FROM AUTHOR]

Aim: Infants with birth asphyxia frequently require resuscitation. Current guidance is to start newborn resuscitation in 21% oxygen. However, infants with severe hypoxia-ischaemia may require prolonged resuscitation with oxygen. To date, no study has looked at the effect of resuscitation in 100% oxygen following a severe hypoxic-ischaemic insult.Methods: Postnatal day 7 Wistar rats underwent a severe hypoxic-ischaemic insult (modified Vannucci unilateral brain injury model) followed by immediate resuscitation in either 21% or 100% oxygen for 30 min. Seven days following the insult, negative geotaxis testing was performed in survivors, and the brains were harvested. Relative ipsilateral cortical and hippocampal area loss was assessed histologically.Results: Total area loss in the affected hemisphere and area loss within the hippocampus did not significantly differ between the two groups. The same results were seen for short-term neurological assessment. No difference was seen in weight gain between pups resuscitated in 21% and 100% oxygen.Conclusion: Resuscitation in 100% oxygen does not cause a deleterious effect on brain injury following a severe hypoxic-ischaemic insult in a rat model of hypoxia-ischaemia. Further work investigating the effects of resuscitation in 100% oxygen is warranted, especially for newborn infants with severe hypoxic-ischaemic encephalopathy. [ABSTRACT FROM AUTHOR]

Introduction While therapeutic hypothermia (TH) is in clinical use, its efficacy in certain patient groups is unclear. This study was designed to describe the characteristics and outcomes of patients with out-of-hospital cardiac-arrest (OHCA) caused by asphyxia, who were treated with TH. Patients and methods A multicentre, retrospective, registry-based study was performed using data from the period 2007–2012. Comatose patients who were treated with TH after asphyxial cardiac arrest were included, while those who with cardiac arrest attributed to hanging, drowning or gas intoxication were excluded. Results Of a total of 932 OHCA patients in the registry, 111 were enrolled in this study. The mean age was 65.8 ± 16.3 years with individuals who were ≥65 years of age accounted for 61.3% of the cohort. Foreign-body airway obstruction was the most common cause (70.3%) of the cardiac arrest. Eighty patients (72.1%) presented with an initial non-shockable rhythm. In all institutions target TH temperatures were 32–34 °C, but TH maintenance times varied. A total of 52 patients (46.8%) survived, of whom six patients (5.4%) showed a good neurologic outcome (cerebral performance category scale 1–2). The pupil light reflex, corneal reflex and time to return of spontaneous circulation ( p = 0.012, 0.015 and 0.032, respectively) were associated with survival. Witnessed arrest, age, previous lung disease, bystander basic life support and time factors were not associated with survival. Conclusion About half of patients who underwent TH after asphyxial cardiac arrest survived, but a very small number showed a good neurologic outcome. The TH maintenance times were not uniform in these patients. Additional research regarding both the appropriate TH guidelines for patients with asphyxial cardiac arrest and improvement of their neurologic outcome is needed. [ABSTRACT FROM AUTHOR]

Study background Previous studies focused on the outcome of avalanche victims with out-of-hospital cardiac arrest (OHCA) after long duration of burial (>35 min); the outcome of victims with short duration (≤35 min) remains obscure. Aim of the study To investigate outcome of avalanche victims with OHCA. Methods Retrospective analysis of avalanche victims with OHCA between 2008 and 2013 in the Tyrolean Alps. Results 55 avalanche victims were identified, 32 of whom were declared dead after extrication without cardiopulmonary resuscitation (CPR), all with long duration of burial. In the remaining 23 CPR was initiated at scene; three were partially and 20 completely buried, nine of whom suffered short and 11 long duration of burial. All nine victims with short duration of burial underwent restoration of spontaneous circulation (ROSC) at scene, four of them after bystander CPR, five after advanced life support by the emergency physician. Two patients with ROSC after short duration of burial and bystander CPR survived to hospital discharge with cerebral performance category 1. None of the 11 victims with long duration of burial survived to hospital discharge, although six were transported to hospital with ongoing CPR and three were supported with extracorporeal circulation. Conclusions In this case series survival with favourable neurological outcome was observed in avalanche victims with short duration of burial only if bystander CPR was immediately performed and ROSC achieved. Strategies for reducing avalanche mortality should focus on prompt extrication from the snow and immediate bystander CPR by uninjured companions. [ABSTRACT FROM AUTHOR]

Objective The purpose of this study is to determine the outcome of foreign body airway obstruction according to the initial actions taken for choking victims during meals. Methods Our subjects were patients who became unresponsive or unconscious because of foreign body airway obstruction (FBAO) during meals in the presence of bystander witnesses. We investigated the associations between outcome and the following factors: age, gender, type of foreign body, chest compressions after the patient became unresponsive or unconscious, episode of cardiac arrest, efforts by a bystander to remove the foreign body, eating-related activities of daily living, time elapsed from the 119 call to arrival of emergency medical technicians (EMTs), and time elapsed from the 119 call to hospital arrival (primary endpoint). Results Of the 138 patients enrolled during the study period, 35 (25.4%) received chest compressions by bystanders after becoming unresponsive or unconscious and 69 (50.0%) suffered cardiac pulmonary arrest. Chest compressions by a bystander after the victim became unresponsive or unconscious ( p < 0.0001) and no CPA ( p < 0.0001) were significantly related to good outcome. Chest compressions by a bystander were both associated with good neurological outcome (odds ratio, 10.57; 95% CI, 2.472–65.059, p < 0.0001). No CPA after FBAO was another independent predictor (odds ratio, 50.512; 95% CI, 13.45–284.41; p < 0.0001), but efforts to remove the foreign body before the arrival of EMTs did not affect outcome. Conclusion Chest compressions by a bystander, a support received by only 25% of the patients, proved to be essential for improved outcome for choking victims who became unresponsive or unconscious. Education for lay-rescuer response to choking might further improve overall outcome. [ABSTRACT FROM AUTHOR]

Aim Asphyxia is the primary cause of death among avalanche victims. Avalanche airbags can lower mortality by directly reducing grade of burial, the single most important factor for survival. This study aims to provide an updated perspective on the effectiveness of this safety device. Methods A retrospective analysis of avalanche accidents involving at least one airbag user between 1994 and 2012 in Austria, Canada, France, Norway, Slovakia, Switzerland and the United States. A multivariate analysis was used to calculate adjusted absolute risk reduction and estimate the effectiveness of airbags on grade of burial and mortality. A univariate analysis was used to examine causes of non-deployment. Results Binomial linear regression models showed main effects for airbag use, avalanche size and injuries on critical burial, and for grade of burial, injuries and avalanche size on mortality. The adjusted risk of critical burial is 47% with non-inflated airbags and 20% with inflated airbags. The adjusted mortality is 44% for critically buried victims and 3% for non-critically buried victims. The adjusted absolute mortality reduction for inflated airbags is -11 percentage points (22% to 11%; 95% confidence interval: -4 to -18 percentage points) and adjusted risk ratio is 0.51 (95% confidence interval: 0.29 to 0.72). Overall non-inflation rate is 20%, 60% of which is attributed to deployment failure by the user. Conclusion Although the impact on survival is smaller than previously reported, these results confirm the effectiveness of airbags. Non-deployment remains the most considerable limitation to effectiveness. Development of standardized data collection protocols is encouraged to facilitate further research. [ABSTRACT FROM AUTHOR]

Abstract: Objective: In contrast to the resuscitation guidelines of children and adults, guidelines on neonatal resuscitation recommend synchronized 90 chest compressions with 30 manual inflations (3:1) per minute in newborn infants. The study aimed to determine if chest compression with asynchronous ventilation improves the recovery of bradycardic asphyxiated newborn piglets compared to 3:1 Compression:Ventilation cardiopulmonary resuscitation (CPR). Intervention and measurements: Term newborn piglets (n =8/group) were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Protocolized resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized to receive resuscitation with either 3:1 compressions to ventilations (3:1C:V CPR group) or chest compressions with asynchronous ventilations (CCaV) or sham. Continuous respiratory parameters (Respironics NM3®), cardiac output, mean systemic and pulmonary artery pressures, and regional blood flows were measured. Main results: Piglets in 3:1C:V CPR and CCaV CPR groups had similar time to return of spontaneous circulation, survival rates, hemodynamic and respiratory parameters during CPR. The systemic and regional hemodynamic recovery in the subsequent 4h was similar in both groups and significantly lower compared to sham-operated piglets. Conclusion: Newborn piglets resuscitated by CCaV had similar return of spontaneous circulation, survival, and hemodynamic recovery compared to those piglets resuscitated by 3:1 Compression:Ventilation ratio. [Copyright &y& Elsevier]

Abstract: Aim: Adequate coronary perfusion pressure (CPP) during cardiopulmonary resuscitation (CPR) is essential for establishing return of spontaneous circulation. The objective of this study was to compare short-term survival using a hemodynamic directed resuscitation strategy versus an absolute depth-guided approach in a porcine model of asphyxia-associated cardiac arrest. We hypothesized that a hemodynamic directed approach would improve short-term survival compared to depth-guided care. Methods: After 7min of asphyxia, followed by induction of ventricular fibrillation, 19 female 3-month old swine (31±0.4kg) were randomized to receive one of three resuscitation strategies: (1) hemodynamic directed care (CPP-20): chest compressions (CCs) with depth titrated to a target systolic blood pressure of 100mmHg and titration of vasopressors to maintain CPP>20mmHg; (2) depth 33mm (D33): target CC depth of 33mm with standard American Heart Association (AHA) epinephrine dosing; or (3) depth 51mm (D51): target CC depth of 51mm with standard AHA epinephrine dosing. All animals received manual CPR guided by audiovisual feedback for 10min before first shock. Results: 45-Min survival was higher in the CPP-20 group (6/6) compared to D33 (1/7) or D51 (1/6) groups; p =0.002. Coronary perfusion pressures were higher in the CPP-20 group compared to D33 (p =0.011) and D51 (p =0.04), and in survivors compared to non-survivors (p <0.01). Total number of vasopressor doses administered and defibrillation attempts were not different. Conclusions: Hemodynamic directed care targeting CPPs>20mmHg improves short-term survival in an intensive care unit porcine model of asphyxia-associated cardiac arrest. [Copyright &y& Elsevier]

Abstract: The present study investigated the protective effects of a novel NHE1 selective inhibitor, sabiporide, in a porcine model of asphyxia-induced cardiac arrest. Asphyxial cardiac arrest was induced by endotracheal tube clamping (ETC). The animals remained untreated for 3min after loss of aortic pulsations (LOAP), and followed by chest compression and defibrillation. Sixteen of eighteen pigs had return of spontaneous circulation (ROSC), and were randomly assigned to two study groups. Group 1: vehicle control. Group 2: 3mg/kg sabiporide was given at 15min after ROSC. Post-arrest myocardial dysfunction was present in both groups, and progressed over hours. Animals treated with sabiporide had less wall motion abnormality and higher left ventricular ejection fraction than control animals (33% in control group vs. 47% in sabiporide group). Sabopiride treatment also significantly improved post-arrest arterial blood pressure by 25% and cardiac stroke volume by 44%, and improved mixed-venous blood oxygen saturation by 38% and oxygen delivery by 118%. Furthermore, compared to the control group, the sabiporide group also had higher blood flows in the brain, heart, kidney, liver and spleen at 30min after ROSC. There was no significant blood flow difference in distal ileum mucosa between control and sabiporide groups. In addition, sabiporide treatment significantly reduced cardiac myeloperoxidase (MPO) activity by 53% and cardiac troponin I by 51%, and reduced the plasma level of TNF-α by 52% and IL-6 by 41%. This study shows that post-arrest pharmacological conditioning with sabiporide affords protection from whole body ischemia–reperfusion injury in this model of asphyxia-induced cardiac arrest and resuscitation. [Copyright &y& Elsevier]

Abstract: Background and aim: The majority of avalanche victims who sustain complete burial die within 35min due to asphyxia and injuries. After 35min, survival is possible only in the presence of a patent airway, and an accompanying air pocket around the face may improve survival. At this stage hypothermia is assumed to be an important factor for survival because rapid cooling decreases oxygen consumption; if deep hypothermia develops before cardiac arrest, hypothermia may be protective and prolong the time that cardiac arrest can be survived. The aim of the study was to investigate the combined effects of hypoxia, hypercapnia and hypothermia in a porcine model of avalanche burial. Methods: Eight piglets were anaesthetised, intubated and buried under snow, randomly assigned to an air pocket (n =5) or ambient air (n =3) group. Results: Mean cooling rates in the first 10min of burial were −19.7±4.7°Ch−1 in the air pocket group and −13.0±4.4°Ch−1 in the ambient air group (P =0.095); overall cooling rates between baseline and asystole were −4.7±1.4°Ch−1 and −4.6±0.2°Ch−1 (P =0.855), respectively. In the air pocket group cardiac output (P =0.002), arterial oxygen partial pressure (P =0.001), arterial pH (P =0.002) and time to asystole (P =0.025) were lower, while arterial carbon dioxide partial pressure (P =0.007) and serum potassium (P =0.042) were higher compared to the ambient air group. Conclusion: Our results demonstrate that hypothermia may develop in the early phase of avalanche burial and severe asphyxia may occur even in the presence of an air pocket. [Copyright &y& Elsevier]

Abstract: Aim of the study: To investigate the effects of early intravenous adrenaline administration on circulatory recovery, cerebral reoxygenation, and plasma catecholamine concentrations, after severe asphyxia-induced bradycardia and hypotension. Methods: One-day-old piglets were left in apnoea until heart rate and mean arterial pressure were less than 50min−1 and 25mmHg, respectively. They randomly received adrenaline, 10μgkg−1 (n =16) or placebo (n =15) and were resuscitated with air ventilation and, when needed, closed-chest cardiac massage (CCCM). Eight not asphyxiated animals served as time controls. Results: CCCM was required in 13 piglets given adrenaline and in 13 given placebo. Time to return of spontaneous circulation was: 72 (66–85)s vs. 77 (64–178)s [median (quartile range)] (p =0.35). Time until cerebral regional oxygen saturation (CrSO2) had increased to 30% was 86 (79–152)s vs. 126 (88–309)s (p =0.30). The two groups did not differ significantly in CrSO2, heart rate, arterial pressure, right common carotid artery blood flow, or number of survivors: 13 vs. 11 animals. Plasma concentration of adrenaline, 2.5min after resuming ventilation, was 498 (268–868)nmoll−1 vs. 114 (80–306)nmoll−1 (p =0.01). Corresponding noradrenaline concentrations were 1799 (1058–4182)nmoll−1 vs. 1385 (696–3118)nmoll−1 (ns). In the time controls, the concentrations were 0.4 (0.2–0.6)nmoll−1 of adrenaline and 1.8 (1.3–2.4)nmoll−1 of noradrenaline. Conclusion: The high endogenous catecholamine levels, especially those of noradrenaline, may explain why early administered adrenaline did not significantly improve resuscitation outcome. [Copyright &y& Elsevier]

Abstract: Objective: This study aimed to evaluate whether GlideScope® is an effective and acceptable method for the removal of a hypopharyngeal foreign body. Methods: This was a prospective study conducted in 28 first year emergency residents with little prior airway management experience. Participants extracted hypopharyngeal foreign bodies using a Macintosh laryngoscope and GlideScope® with Magill and Sponge forceps. The primary endpoints were extraction time and success rate with each device. Participant preferences were also assessed. Results: The cumulative success rate in relation to time to extraction was significantly higher with the Macintosh laryngoscope than with the GlideScope® (p <0.001) regardless of the extraction device. Significantly fewer attempts were required for the first successful extraction with the Macintosh laryngoscope versus GlideScope® with Magill forceps (p =<0.001) and Sponge forceps (p =<0.001). The time for successful foreign body extraction using GlideScope® was significantly lower when using Magill (median 46s, IQR 28–75s) forceps than Sponge forceps (median 79s, IQR 41–88s). Conclusions: In this cadaver model, the Macintosh laryngoscope appeared to be more efficient and preferred than GlideScope® for extracting hypopharyngeal airway foreign bodies that are associated with fatal asphyxiation. [Copyright &y& Elsevier]

Abstract: Aim: We aimed to describe characteristics associated with rescue from drowning as reported by the Swedish Fire and Rescue Services (SFARS) and their association with survival from the Out of Hospital Cardiac Arrest (OHCA) registry. Method: This retrospective study is based on the OHCA registry and the Swedish Civil Contingencies Agency (SCCA) registry. All emergency calls (1996–2010) where the SFARS were dispatched were included (n =7175). For analysis of survival, OHCAs that matched events from the SCCA registry were included (n =250). Results: Calls to lakes and ponds were predominant (35% of all calls reported). Rescues were more likely in cold water, <10°C (45%), in open water (80%) and in April–September (68%). Median delay from a call to arrival of rescue services was 8min, while it was 9min for rescue diving units. Of all OHCA cases, the victim was found at the surface in 47% and underwater in 38%. In events where rescue divers were used, victims were significantly younger than in non-diving cardiac arrests and the mean diving depth was 6.3±5.8m. Overall survival to one month was 5.6% (13% in diving and 4.7% in non-diving cases; p =0.07). Conclusion: In half of more than 7000 drowning-related calls to the SFARS during 15 years of practice, water rescue was needed. In all treated OHCA cases, the majority were found at the surface. Only in a small percentage did rescue diving take place. In these cases, survival did not appear to be poorer than in non-diving cases. [Copyright &y& Elsevier]

Abstract: Aim of the study: Early initiation of basic resuscitation interventions within 60s in apneic newborn infants is thought to be essential in preventing progression to circulatory collapse based on experimental cardio-respiratory responses to asphyxia. The objectives were to describe normal transitional respiratory adaption at birth and to assess the importance of initiating basic resuscitation within the first minutes after birth as it relates to neonatal outcome. Methods: This is an observational study of neonatal respiratory adaptation at birth in a rural hospital in Tanzania. Research assistants (n =14) monitored every newborn infant delivery and the response of birth attendants to a depressed baby. Time to initiation of spontaneous respirations or time to onset of breathing following stimulation/suctioning, or face mask ventilation (FMV) in apneic infants, and duration of FMV were recorded. Results: 5845 infants were born; 5689 were liveborn, among these 4769(84%) initiated spontaneous respirations; 93% in ≤30s and 99% in ≤60s. Basic resuscitation (stimulation, suction, and/or FMV) was attempted in 920/5689(16.0%); of these 459(49.9%) received FMV. Outcomes included normal n =5613(96.0%), neonatal deaths n =56(1.0%), admitted neonatal area n =20(0.3%), and stillbirths n =156(2.7%). The risk for death or prolonged admission increases 16% for every 30s delay in initiating FMV up to six minutes (p =0.045) and 6% for every minute of applied FMV (p =0.001). Conclusions: The majority of lifeless babies were in primary apnea and responded to stimulation/suctioning and/or FMV. Infants who required FMV were more likely to die particularly when ventilation was delayed or prolonged. [Copyright &y& Elsevier]

Abstract: Aim: To study the effects of the combination of adrenaline (epinephrine) and vasopressin compared to adrenaline alone on initial resuscitation success, 24h survival, and neurological outcome in a swine model of asphyxial cardiac arrest (CA). Methods: This prospective randomized experimental study was conducted at a laboratory research department. Twenty female Landrace/Large-White pigs, 12–15weeks of age, were investigated. Asphyxial CA was induced by clamping of the endotracheal tube. After 4min of untreated CA, resuscitation was initiated by unclamping the endotracheal tube, mechanical ventilation, chest compressions and adrenaline (Group A) or a combination of adrenaline with vasopressin (Group A+V) administered intravenously. In case of restoration of spontaneous circulation (ROSC), the animals were monitored for 30min and then observed for 24h. Results: Hemodynamic variables were measured at baseline during CPR and in the post-resuscitation period. Statistically significant difference was observed in groups A and A+V regarding coronary perfusion pressure (CPP) during the first minute of CPR. In both groups, ROSC and survival rates were comparable (p =NS). Neurological deficit score (NDS) was significantly higher in the combination group 24h following CA (p <0.001). Brain histological damage score (HDS) was also better in the combination group (p <0.001). Total HDS and NDS showed a statistical significant correlation (p <0.001). Conclusions: In this porcine model of asphyxial CA, adrenaline alone as well as the combined administration of adrenaline and vasopressin resulted in similar ROSC and survival rates, but the combination of adrenaline and vasopressin resulted in improved neurological and cerebral histopathological outcomes. [Copyright &y& Elsevier]

Abstract: Objective: To study the feasibility, efficacy and safety of using the laryngeal mask airway (LMA) in neonatal resuscitation. Methods: In total, 369 neonates (gestational age ≥34 weeks, expected birth weight ≥2.0kg) requiring positive pressure ventilation at birth were quasi-randomised to resuscitation by LMA (205 neonates) or bag-mask ventilation (164 neonates). Results: (1) Successful resuscitation rate was higher with the LMA compared with bag-mask ventilation (P <0.001) and the total ventilation time was shorter with the LMA than with bag-mask ventilation (P <0.001). Seven of nine neonates with an Apgar score of 2 or 3 at 1min after birth were successfully resuscitated in the LMA group, while in the BMV group all six neonates with an Apgar score of 2 or 3 at 1min required tracheal intubation and ventilation. In neonates with an Apgar score of 4 or 5 at 1min after birth, successful resuscitation rate with the LMA was higher than with bag-mask ventilation (P <0.01). (2) Successful insertion rate of the LMA at the first attempt was 98.5% and the insertion time was 7.8s±2.2s. There were few adverse events (vomiting and aspiration) in the LMA group. Conclusion: The LMA is safe, effective and easy to implement for the resuscitation of neonates with a gestational age of 34 or, more weeks. [Copyright &y& Elsevier]

Abstract: 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 10min. 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. [Copyright &y& Elsevier]

Abstract: Objective: The study investigated a possible neuroprotective potency of minocycline in an experimental asphyxial cardiac arrest (ACA) rat model. Clinically important survival times were evaluated thus broadening common experimental approaches. Methods: Adult rats were subjected to 5min of ACA followed by resuscitation. There were two main treatment groups: ACA and sham operated. Relating to minocycline treatment each group consisted of three sub-groups: pre-, post-, and sans-mino, with three different survival times: 4, 7, and 21 days. Neurodegeneration and microgliosis were monitored by immunohistochemistry. Alterations of microglia-associated gene expression were analyzed by quantitative RT-PCR. Results: ACA induced massive nerve cell loss and activation of microglia/macrophages in hippocampal CA1 cell layer intensifying with survival time. After 7 days, minocycline significantly decreased both, neuronal degeneration and microglia response in dependence on the application pattern; application post ACA was most effective. After 21 days, neuroprotective effects of minocycline were lost. ACA significantly induced expression of the microglia-associated factors Ccl2, CD45, Mac-1, F4-80, and Tnfa. Independent on survival time, minocycline affected these parameters not significantly. Expression of iNOS was unaffected by both, ACA and minocycline. Conclusions: In adult rat hippocampus microglia was significantly activated by ACA. Minocycline positive affected neuronal survival and microglial response temporary, even when applied up to 18h after ACA, thus defining a therapeutically-relevant time window. As ACA-induced neuronal cell death involves acute and delayed events, longer minocycline intervention targeting also secondary injury cascades should manifest neuroprotective potency, a question to be answered by further experiments. [Copyright &y& Elsevier]

Abstract: Aim of the study: Improvement in the quality of cardiopulmonary resuscitation (CPR) may improve the survival rate following cardiac arrest. The aims of our study were to describe how recording of CPR maneuvers performed in our emergency department with real-time video and regular feedback learning may improve CPR. Methods: A digital video-recording system enabled us to record and analyze CPR procedures for adult patients from March 2007 to July 2008. Our resuscitation teams received video-recording feedback learning every week. Results and conclusions: We analyzed 45 cases, divided into three groups of 15 consecutive patients. Instantaneous rates of chest compression showed variation with 75% exceeding 110cpm. There was a significant difference in instantaneous rates among groups (135 [112–150] in group 1, 123 [110–136] in group 2 and 124 [111–137]cpm in group 3, P < 0.001). Ratio of hands-off time to total manual compression time (%) significantly decreased over time (Spearman correlation=−0.30, P =0.04). There were significant differences in hands-off time per minute among the groups (11 [3–28], 6 [2–21] and 7 [2–19]smin−1, P < 0.001). There was a significant improvement in time delay to first chest compression (11 [5–50], 20 [8–68] and 0 [0–12]s, P =0.01), but not in time delay to first ventilation (91 [31–190], 65 [17–121] and 24 [9–64]s, P =0.08). Data are median [25–75% interquartile]. Regular feedback learning from real-time video recording may improve the quality of major CPR variables. [ABSTRACT FROM AUTHOR]

Abstract: Background: The rationale for a compression to ventilation ratio of 3:1 in neonates with primary hypoxic, hypercapnic cardiac arrest is to emphasize the importance of ventilation; however, there are no published studies testing this approach against alternative methods. An extended series of cardiac compressions offers the theoretical advantage of improving coronary perfusion pressures and hence, we aimed to explore the impact of compression cycles of two different durations. Materials and methods: Newborn swine (n =32, age 12–36h, weight 2.0–2.7kg) were progressively asphyxiated until asystole occurred. Animals were randomized to receive compressions:ventilations 3:1 (n =16) or 9:3 (n =16). Return of spontaneous circulation (ROSC) was defined as a heart rate ≥100beatsmin−1. Results: All animals except one in the 9:3 group achieved ROSC. One animal in the 3:1 group suffered bradycardia at baseline, and was excluded, leaving us with 15 animals in each group surviving to completion of protocol. Time to ROSC (median and interquartile range) was 150s (115–180) vs. 148s (116–195) for 3:1 and 9:3, respectively (P =0.74). There were no differences in diastolic blood pressure during compression cycles or in markers of hypoxia and inflammation. The temporal changes in mean arterial blood pressure, heart rate, arterial blood gas parameters, and systemic and regional oxygen saturation were comparable between groups. Conclusion: Neonatal pigs with asphyxia-induced cardiac arrest did not respond to a compression:ventilation ratio of 9:3 better than to 3:1. Future research should address if alternative compression:ventilation ratios offer advantages over the current gold standard of 3:1. [Copyright &y& Elsevier]

Abstract: Background: Video-based self-instruction (VSI) with a 24-min DVD and a personal resuscitation manikin solves some of the barriers associated with traditional basic life support (BLS) courses. No accurate assessment of the actual improvement in skills after attending a VSI course has been determined, and in this study we assess the skill improvement in laypersons undergoing VSI. Methods: The BLS skills of 68 untrained laypersons (high school students, their teachers and persons excluded from mainstream society) were assessed using the Laerdal ResusciAnne and PC Skill Reporting System 2.0 in a 3min test. A total score (12–48 points) was calculated and 12 different variables were recorded. The participants attended a 24-min VSI course (MiniAnne, Laerdal) and took home the DVD and manikin for optional subsequent self-training. We repeated the test 3½–4 months later. Results: There was a significant increase in the total score (p <0.0001) from 26.5 to 34 points. The participants performed significantly better in checking responsiveness, opening the airway, checking for respiration and using the correct compression/ventilation ratio (all p-values<0.001). The compression depth improved from 38mm to 49.5mm and the total number of compressions increased from 67 to 141. The ventilation volume and the total number of ventilations increased, and total “hands-off” time decreased from 120.5s to 85s. Conclusions: Untrained laypersons attending a 24min DVD-based BLS course have a significantly improved BLS performance after 3½–4 months compared to pre-test skill performance. Especially the total number of compressions improved and the hands-off time decreased. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: This study aimed to compare the time-dependent deterioration of chest compressions between chest compression-only cardiopulmonary resuscitation (CPR) and conventional CPR. Methods: This study involved 106 and 107 participants randomly assigned to chest compression-only CPR training and conventional CPR training, respectively. Immediately after training, participants were asked to perform CPR for 2min and the quality of their CPR skills were evaluated. The number of chest compressions in total and those with appropriate depth were counted every 20-s CPR period from the start of CPR. The primary outcome was the CPR quality index calculated as the proportion of chest compressions with appropriate depth among total chest compressions. Results: The total number of chest compressions remained stable over time both in the chest compression-only and the conventional CPR groups. The CPR quality index, however, decreased from 86.6±25.0 to 58.2±36.9 in the chest compression-only CPR group from 0–20s through 61–80s. The reduction was greater than in the conventional CPR group (85.9±25.5 to 74.3±34.0). The difference in the CPR quality index reached statistical significance (p =0.003) at 61–80s period. Conclusions: Chest compressions with appropriate depth decreased more rapidly during chest compression-only CPR than conventional CPR. We recommend that CPR providers change their roles every 1min to maintain the quality of chest compressions during chest compression-only CPR. (UMIN-CTR C0000000321) [ABSTRACT FROM AUTHOR]

Abstract: Aim: To develop a new method to suppress the artefact generated by chest compressions during cardiopulmonary resuscitation (CPR) using only the frequency of the compressions as additional information. Materials and methods: The CPR artefact suppression method was developed and tested using a database of 381 ECG records (89 shockable and 292 non-shockable) from 299 patients. All records were extracted from real out-of-hospital cardiac arrest episodes. The suppression method consists of a Kalman filter that uses the frequency of the measured compressions to estimate the artefact and to remove it from the ECG. The performance of the filter was evaluated by comparing the sensitivity and specificity of an automated external defibrillator before and after the artefact suppression. Results: For the test database, the sensitivity improved from 57.8% (95% confidence interval, 43.3–71.0%) to 93.3% (81.5–98.4%) and the specificity decreased from 92.5% (87.0–95.9%) to 89.1% (83.0–93.3%). Conclusion: For a similar sensitivity, we obtained better specificity than that reported for other methods, although still short of the values recommended by the American Heart Association. The results suggest that the CPR artefact can be accurately modelled using only the frequency of the compressions. This information could be easily acquired through the defibrillator''s CPR help pads, with minimal hardware modifications. [Copyright &y& Elsevier]

Abstract: Aim: Food asphyxiation is uncommon but unignorable cause of sudden death in the elderly. Several autopsy studies, which identified those at particular risk, have been conducted on the subject. Resuscitation profiles and outcomes of food asphyxiation victims presenting with out-of-hospital cardiac arrest (OHCA) to the emergency department, however, have rarely been reported. Methods: Data on adults (≥20 years) presenting with OHCA after witnessed food asphyxiation were retrieved from an institutional database. Clinical variables were evaluated to identify their demographic characteristics. Their outcomes, represented by return of spontaneous circulation (ROSC) and survival rate, were also investigated. Results: Sixty-nine food asphyxiation victims presenting with OHCA were identified during the 4-year period. Food asphyxiation occurred most frequently in the age group of 71–80 years, followed by that of 81–90 years. The majority of victims had medical conditions that adversely affected mastication/swallowing, such as dementia. Bystander cardiopulmonary resuscitation (CPR) was performed only in 26%, although bystanders often attempted to clear the airway without performing CPR. Despite the high ROSC rate of 78%, only 7% survived to discharge. Asphyxiation–ROSC interval might play a crucial role in determining the outcomes: the interval was ≤10min in all survivors, while it was longer than 10min in all non-survivors. Conclusion: Because of their advanced age and debilitating general condition, it may be difficult to substantially improve the outcomes of food asphyxiation victims. Effort should be directed to prevent food asphyxiation, and public education to perform standard CPR for food asphyxiation victims including the Heimlich manoeuvre is warranted. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Avalanche resuscitation will save lives if focussed on victims that have the potential to survive. The purpose of this systematic review was to examine 4 critical prognostic factors for burial victims in cardiac arrest. Methods: Time of burial, airway patency, core temperature and serum potassium level were analyzed as PICO (Patient/population, Intervention, Comparator, Outcome) questions within the 2010 Consensus on Science process of the International Liaison Committee on Resuscitation. The electronic databases of Medline via PubMed, EMBASE via OVID and the Cochrane Database of Systematic Reviews were searched using combinations of the search terms “avalanche”, “air pocket”, “hypothermia” and “serum potassium”. Results: Of 1910 publications that were identified 30 were found relevant. The predictive value for survival of a short time of burial or a patent airway after 35min of burial is supported by 10 retrospective case–control studies, 4 case series and 2 experimental studies, while no studies are neutral or opposed. A core temperature of less than 32°C with a patent airway is supported by 2 retrospective case–control studies and 3 case series, while 10 studies are neutral. Serum potassium level is supported by 6 retrospective case–control studies and 3 case reports, while 3 retrospective case–control studies and 1 animal model are neutral. Conclusion: After 35min of burial, or where the core temperature is less than 32°C, a patent airway is associated with survival to hospital discharge. A serum potassium of less than 7mmol/L may be a valuable indicator for survival when other indicators are unclear. These findings should modify the current avalanche resuscitation scheme. [Copyright &y& Elsevier]

Abstract: 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 2mmHg. The TLV animals underwent asphyxial arrest for an additional 2min after LOAP, followed by 3min of hypothermia, prior to starting CPR. The C animals underwent 5min of asphyxia beyond LOAP. Both groups then underwent CPR for at least 10min. The endpoint was the resumption of spontaneous circulation maintained for 10min. 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 4min after induction of hypothermia (TLV 36.3±0.2°C vs. C 38.1±0.2°C, p <0.0001). Arterial was higher in total liquid ventilation animals at 2.5min of CPR (TLV 76±12mmHg vs. C 44±2mmHg; 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. [Copyright &y& Elsevier]

Abstract: Objective: The present study investigated the impact of the vascular access site for cardiac output (CO) measurement by thermodilution on survival and neurohistopathological injury in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Secondary the influence of the vascular access site on cardiac output measurements was examined. Methods: Rats underwent asphyxial CA and CPR. Thermocouple probes were either placed via the femoral artery into the bifurcation of abdominal aorta/iliac artery (Femoral) or via the carotid artery into the aortic arch (Carotid). CPR was initiated after 9min CA. Local cerebral blood flow (lCBF) and CO were assessed for 120min after restoration of spontaneous circulation. Neurohistopathological injury was determined using Fluoro-Jade B staining. Results: Survival was reduced in the Carotid group compared to the Femoral group (p <0.01). Fluoro-Jade B staining in the hippocampus showed no difference between CA groups. CO measurements were comparable between femoral and carotid artery access sites. lCBF revealed a delayed hyperperfusion in the Carotid group only. Conclusions: The present study demonstrates the influence of the vascular access site for placing thermocouple probes for CO measurement on animal survival after CA/CPR. CO did not differ between the two access sites with consequential different detection sites. Use of the femoral access for CO measurement is recommended for long-term survival after CA/CPR. [Copyright &y& Elsevier]

Abstract: Background: The use of emergency cardiopulmonary bypass (ECPB) resuscitation after cardiac arrest may offer hope for survival when standard ACLS therapies fail. However, whether cooling adds benefit to ECPB is unknown and we lack an ECPB rodent model for experimental studies. We sought to (a) develop a 72h survival rodent model using ECPB to treat asphyxial cardiac arrest and (b) use this new model to evaluate early mild and moderate hypothermia versus normothermia during ECPB resuscitation. Methods: After 8min of normothermic asphyxia, three groups of rats were resuscitated with ECPB at 37°C (NORM), 34°C (MILD) and 30°C (MOD) for 1h (n =10 each). During the second resuscitation hour, ECPB was discontinued, ventilatory support was provided and body temperatures were maintained at 37°C for NORM, 34°C for MILD, and from 30°C gradually up to 34°C in 1h for MOD animals. From hours 3 to 8, body temperature was maintained at 37°C for NORM and 34°C for MILD and MOD animals. Results: All rats were initially resuscitated by ECPB. After 72h, neurological outcome and survival in the MILD (60% survival) and MOD (80%) groups were significantly better than in the NORM (0%) group (p <0.05). Overall performance recovery in the MOD group was best (vs. the NORM group), while the MILD group had an intermediate outcome. Conclusions: A rodent model of ECPB is feasible and useful for resuscitation studies. The addition of early mild and moderate hypothermia to ECPB resuscitation significantly improves survival compared with normothermic ECPB in rats. [Copyright &y& Elsevier]

Summary: Background: The incidence of pulseless electrical activity (PEA) as a presenting rhythm during cardiac arrest is increasing. The current animal models of PEA arrest, post-countershock or total asphyxiation, unreliably generate PEA for a specific time period. Neither of these models predictably generate pseudo-PEA. The purpose of this study was to create an animal model of pseudo-PEA that will allow for a prolonged time period in this arrest state for future research. Methods: In a laboratory setting, five ventilated swine on inhaled anesthesia and 100% oxygen with continuous EKG recordings were instrumented with central aortic and venous pressure-transducing catheters. Animals were then switched to intravenous anesthesia while being ventilated with a 16% oxygen/84% nitrogen mix. Continuous EKG, aortic and venous pressures were recorded to a computerized data collection program. Arterial blood gas samples were taken every 10min. Time until onset of pseudo-PEA, duration of pseudo-PEA, and cardiac rhythm during pseudo-PEA were recorded. Results: Mean time to onset of pseudo-PEA was 80.6±47.3min. Mean duration of pseudo-PEA was 18.6±6.2min. Mean arterial pH at pseudo-PEA onset was 7.20±0.05 with a mean associated base excess of −11.4±−5.94. No significant differences were noted in other recorded variables. Conclusions: Partial asphyxiation using a 16% oxygen/84% nitrogen mix is a reliable laboratory method to create a prolonged state of pseudo-PEA in a swine model. The mechanism generating pseudo-PEA is hypoxemia-induced systemic acidosis. This model will allow sufficient time in this low-flow cardiac state for future research to be conducted. [Copyright &y& Elsevier]

Summary: Background: Asphyxia is one of the most common causes of pediatric cardiac arrest, and becoming a more frequently recognized cause in adults. Periodic acceleration (pGz) is a novel method of cardiopulmonary resuscitation (CPR). pGz is achieved by rapid motion of the supine body headward–footward that generates adequate perfusion and ventilation during cardiac arrest. In a swine ventricular fibrillation cardiac arrest model, pGz produced a higher return of spontaneous circulation (ROSC), superior neurological outcome, less echocardiography evidence of post resuscitation myocardial stunning, and decreased indices of tissue injury. In contrast to standard chest compression CPR, pGz does not produce rib fractures. We investigated the feasibility of pGz in severe asphyxia cardiac arrest and assessed whether beneficial effects seen in the VF model of cardiac arrest could be realized. Methods and results: Sixteen swine weight 4±1kg were anesthetized, tracheally intubated, and instrumented to measure, hemodynamics and echocardiography. Asphyxia was induced by occlusion of the tracheal tube. After loss of aortic pulsations (median time 10min) animals were observed for three additional minutes following which all were in cardiac arrest. The animals were then randomized to receive 10min of pGz or standard chest compression ventilation performed with a commercial device (Thumper®). A single dose of epinephrine (adrenaline) and sodium bicarbonate were given and defibrillation attempted if appropriate for a maximum of 10min. Both groups received fractional inspired O2 concentration of 100% during CPR and after resuscitation. Four animals in each group (50%) had an initial ROSC, however only two of the four initial survivors remained alive 3h after ROSC. There were no significant differences in blood pressure, coronary perfusion pressure during CPR and after early ROSC between groups. pGz treated animals had significantly lower pulmonary artery pressure; 20±4mmHg compared to Thumper 46±5mmHg, 30min after ROSC (p <0.01). Surviving animals in both groups had severe myocardial dysfunction at 30min after ROSC. At necropsy, 25% of the Thumper treated animals had rib fractures, while none occurred in the pGz group. Conclusions: In a lethal model of asphyxia cardiac arrest, pGz is equivalent to standard CPR, with respect to acute outcomes and resuscitation survival rates but is associated with significantly lower pulmonary artery pressures and does not produce traumatic rib fractures. [Copyright &y& Elsevier]

Summary: Purpose: To determine the effect of repeated intermittent apnea and resuscitation with 100% vs. 21% oxygen enriched gas on levels of key regulatory proteins contributing to cell death (Bax, Caspase-3) or protecting neurons from hypoxic/ischemic injury (Bcl-2, p-Akt, p-CREB). Methods: The anaesthetized, mechanically ventilated newborn piglets underwent 10 episodes of apnea with resuscitation either with 100% or with 21% oxygen. Following 6h recovery the animals were sacrificed painlessly, the brain dissected out and used to determine levels of Bcl-2, Bax, Caspase-3, p-Akt and p-CREB in the striatum, frontal cortex, midbrain and hippocampus were studied. Results: In hippocampus and striatum, Bcl-2 expression was higher with 100% vs. 21% group (173±29% vs. 121±31%, p <0.05 and 189±10% vs. 117±47%, p <0.01, respectively) whereas the Bax expression was lower (88±3% vs. 100±9%, p <0.05 and 117±5% vs. 133±10%, p <0.05, respectively). Expression of Caspase-3 in the striatum, was lower with 100% vs. 21% group (197±35% vs. 263±33%, p <0.05, respectively) but not different in the hippocampus. p-Akt expression was higher with 100% vs. 21% oxygen in the hippocampus and striatum (225±44% vs. 108±35%, p <0.01 and 215±12% vs. 164±16%, p <0.01, respectively). The p-CREB expression was higher with 100% vs. 21% oxygen resuscitation in the hippocampus (217±41% vs. 132±30%, p <0.01) with no changes in striatum. Much smaller or insignificant differences between 100% vs. 21% oxygen groups were observed in the frontal cortex and midbrain, respectively. Conclusion: In neonatal piglet model of intermittent apnea, selectively vulnerable regions of brain (striatum and hippocampus) are better protected from apoptotic injury when resuscitation was conducted with 100%, rather than 21%, oxygen. [Copyright &y& Elsevier]