Patrick Braun

LUCAS compared to manual cardiopulmonary resuscitation is more effective during helicopter rescue-a prospective, randomized, cross-over manikin study.

OBJECTIVE High-quality chest-compressions are of paramount importance for survival and good neurological outcome after cardiac arrest. However, even healthcare professionals have difficulty performing effective chest-compressions, and quality may be further reduced during transport. We compared a mechanical chest-compression device (Lund University Cardiac Assist System [LUCAS]; Jolife, Lund, Sweden) and manual chest-compressions in a simulated cardiopulmonary resuscitation scenario during helicopter rescue. METHODS Twenty-five advanced life support-certified paramedics were enrolled for this prospective, randomized, crossover study. A modified Resusci Anne manikin was employed. Thirty minutes of training was allotted to both LUCAS and manual cardiopulmonary resuscitation (CPR). Thereafter, every candidate performed the same scenario twice, once with LUCAS and once with manual CPR. The primary outcome measure was the percentage of correct chest-compressions relative to total chest-compressions. RESULTS LUCAS compared to manual chest-compressions were more frequently correct (99% vs 59%, P < .001) and were more often performed correctly regarding depth (99% vs 79%, P < .001), pressure point (100% vs 79%, P < .001) and pressure release (100% vs 97%, P = .001). Hands-off time was shorter in the LUCAS than in the manual group (46 vs 130 seconds, P < .001). Time until first defibrillation was longer in the LUCAS group (112 vs 49 seconds, P < .001). CONCLUSIONS During this simulated cardiac arrest scenario in helicopter rescue LUCAS compared to manual chest-compressions increased CPR quality and reduced hands-off time, but prolonged the time interval to the first defibrillation. Further clinical trials are warranted to confirm potential benefits of LUCAS CPR in helicopter rescue.

Factors affecting survival from avalanche burial—A randomised prospective porcine pilot study

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.

Anesthesia in prehospital emergencies and in the emergency department

Purpose of review Recently, notable progress has been made in the field of anesthesia drugs and airway management. Recent findings Anesthesia in prehospital emergencies and in the emergency department is reviewed and guidelines are discussed. Summary Preoxygenation should be performed with high-flow oxygen delivered through a tight-fitting face mask with a reservoir. Ketamine may be the induction agent of choice in hemodynamically unstable patients. The rocuronium antagonist sugammadex may have the potential to make rocuronium a first-line neuromuscular blocking agent in emergency induction. Experienced healthcare providers may consider prehospital anesthesia induction. Moderately experienced healthcare providers should optimize oxygenation, hasten hospital transfer and only try to intubate a patient whose life is threatened. When intubation fails twice, ventilation should be performed with an alternative supraglottic airway or a bag–valve–mask device. Lesser experienced healthcare providers should completely refrain from intubation, optimize oxygenation, hasten hospital transfer and ventilate patients only in life-threatening circumstances with a supraglottic airway or a bag–valve–mask device. Senior help should be sought early. In a ‘cannot ventilate-cannot intubate’ situation, a supraglottic airway should be employed and, if ventilation is still unsuccessful, a surgical airway should be performed. Capnography should be used in every ventilated patient. Clinical practice is essential to retain anesthesia and airway management skills.

How the media and animal rights activists put avalanche burial study on ice.

Why did a research study into the effects of hypothermia on avalanche survival hit central European headlines earlier this year and spark 35 000 protest emails? Peter Paal and colleagues report

Monitoring of brain oxygenation during hypothermic CPR – A prospective porcine study

BACKGROUND AND AIM Limited data are available concerning the impact of CPR interventions on cerebral oxygenation during hypothermic cardiac arrest. We therefore studied cerebral perfusion pressure (CPP), brain tissue oxygen tension (PbtO2), cerebral venous oxygen saturation (ScvO2) and regional cerebral oxygen saturation (rSO2) in an animal model of hypothermic CPR. We also assessed the correlation between rSO2 and CPP, PbtO2 and ScvO2 to clarify whether near-infrared spectroscopy (NIRS) may be used to non-invasively monitor changes in cerebral oxygenation during hypothermic CPR. METHODS Nine pigs were surface-cooled to a core temperature of 28°C and underwent a period of asphyxia before cardiac arrest was induced. After 2min of untreated cardiac arrest they were resuscitated for 45min. CPP, PbtO2, ScvO2 and rSO2 were monitored after periods of stable external chest compression, a short interruption of CPR and after epinephrine administration. RESULTS During external chest-compressions before adrenalin administration CPP, PbtO2, ScvO2 and rSO2 increased in parallel and changes in rSO2 closely correlated with changes in CPP (r=.844; p<.001) and ScvO2 (r=.868; p<.001). After adrenaline administration CPP and PbtO2 increased, ScvO2 decreased and rSO2 values did not change and there was no significant correlation between rSO2 and CPP, PbtO2, or ScvO2. CONCLUSION In this animal model of hypothermic cardiac arrest adrenaline was associated with an increase in global cerebral oxygen extraction despite an increase in CPP. Discrepancies in the time course of PbtO2 and ScvO2 suggest differences in regional oxygen metabolism after adrenalin. rSO2 values correlated closely with CPP and ScvO2 only during periods of external chest compression without adrenaline administration.

A Dual-Use Laryngoscope to Facilitate Apneic Oxygenation

BACKGROUND In preoxygenated patients, time until oxygen saturation drops can be extended by insufflating oxygen into their airways, thus oxygenating them apneically. OBJECTIVES To compare different methods of apneic oxygenation. METHODS A noncommercial dual-use laryngoscope with an internal lumen in its blade was used to provide oxygen insufflation into a simulated laryngeal space during intubation. In this experimental study, oxygen insufflation via the dual-use laryngoscope was compared with no oxygen insufflation, with nasal oxygen insufflation, and with direct intratracheal oxygen insufflation. In a preoxygenated test lung of a manikin, oxygen percentage decrease was measured over a 20-min observation period for each method of oxygen application. RESULTS Oxygen percentage in the test lung dropped from 97% to 37 ± 1% in the control group (p < 0.001 compared to all other groups) and to 68 ± 1% in the nasal insufflation group (p < 0.001 compared to all other groups). Oxygen percentage remained over 90% in both the direct intratracheal insufflation group (96 ± 0%) and the laryngoscope blade insufflation group (94 ± 1%) (p < 0.01 between the latter two groups). CONCLUSIONS Simulating apneic oxygenation in a preoxygenated manikin, deep laryngeal oxygen insufflation via the dual-use laryngoscope kept oxygen percentage in the test lung above 90%, and was more effective than oxygen insufflation via nasal prongs.

Manual versus Mechanical Chest Compressions on Surfaces of Varying Softness with or without Backboards: A Randomized, Crossover Manikin Study

BACKGROUND Chest compression quality is decisive for overall outcome after cardiac arrest. Chest compression depth may decrease when cardiopulmonary resuscitation (CPR) is performed on a mattress, and the use of a backboard does not necessarily improve compression depth. Mechanical chest compression devices may overcome this problem. OBJECTIVES We sought to investigate the effectiveness of manual chest compressions both with and without a backboard compared to mechanical CPR performed on surfaces of different softness. METHODS Twenty-four advanced life support (ALS)-certified rescuers were enrolled. LUCAS2 (Physio-Control, Redmond, WA) delivers 52 ± 2 mm deep chest compressions and active decompressions back to the neutral position (frequency 102 min(-1); duty cycle, 50%). This simulated CPR scenario was performed on a Resusci-Anne manikin (Laerdal, Stavanger, Norway) that was lying on 3 different surfaces: 1) a concrete floor, 2) a firm standard mattress, and 3) a pressure-relieving mattress. Data were recorded by the Laerdal Skill Reporting System. RESULTS Manual chest compression with or without a backboard were performed correctly less often than mechanical chest compressions (floor: 33% [interquartile range {IQR}, 27-48%] vs. 90% [IQR, 86-94%], p < 0.001; standard mattress: 32% [IQR, 20-45%] vs. 27% [IQR, 14-46%] vs. 91% [IQR, 51-94%], p < 0.001; and pressure-relieving mattress 29% [IQR, 17-49%] vs. 30% [IQR, 17-52%] vs. 91% [IQR, 87-95%], p < 0.001). The mean compression depth on both mattresses was deeper with mechanical chest compressions (floor: 53 mm [range, 47-57 mm] vs. 56 mm [range, 54-57 mm], p = 0.003; standard mattress: 50 mm [range, 44-55 mm] vs. 51 mm [range, 47-55 mm] vs. 55 mm [range, 54-58 mm], p < 0.001; and pressure-relieving mattress: 49 mm [range, 44-55 mm] vs. 50 mm [range, 44-53 mm] vs. 55 mm [range, 55-56 mm], p < 0.001). In this ∼6-min scenario, the mean hands-off time was ∼15 to 20 s shorter in the manual CPR scenarios. CONCLUSIONS In this experimental study, only ∼30% of manual chest compressions were performed correctly compared to ∼90% of mechanical chest compressions, regardless of the underlying surface. Backboard use did not influence the mean compression depth during manual CPR. Chest compressions were deeper with mechanical CPR. The mean hands-off time was shorter with manual CPR.

Effects of Stomach Inflation on Cardiopulmonary Function and Survival During Hemorrhagic Shock: A Randomized, Controlled, Porcine Study

Background: Ventilation of an unprotected airway may result in stomach inflation. The purpose of this study was to evaluate the effect of clinically realistic stomach inflation on cardiopulmonary function during hemorrhagic shock in a porcine model. Methods: Pigs were randomized to a sham control group (n = 9), hemorrhagic shock (35 mL kg−1 over 15 min [n = 9]), and hemorrhagic shock combined with stomach inflation (35 mL kg−1 over 15 min and 5 L stomach inflation [n = 10]). Results: When compared with the control group, hemorrhagic shock (n = 9) increased heart rate (103 ± 11 vs. 146 ± 37 beats min−1; P = 0.002) and lactate (1.4 ± 0.5 vs. 4.0 ± 1.9 mmol L−1; P < 0.001), and decreased mean arterial blood pressure (81.3 ± 12.8 vs. 35.4 ± 8.1 mmHg; P < 0.001) and stroke-volume index (38.1 ± 6.4 vs. 13.6 ± 4.8 mL min−1 m−2; P < 0.001). Hemorrhagic shock combined with stomach inflation (n = 10) versus hemorrhagic shock only (n = 9) increased intra-abdominal pressure (27.0 ± 9.3 vs. 1.1 ± 1.0 mmHg; P < 0.001), and decreased stroke-volume index (9.9 ± 6.0 vs. 20.8 ± 8.5 mL min−1 m−2; P = 0.007), and dynamic respiratory system compliance (10.8 ± 4.5 vs. 38.1 ± 6.1 mL cmH2O−1; P < 0.001). Before versus after stomach evacuation during hemorrhagic shock, intra-abdominal pressure decreased (27.0 ± 9.3 vs. 9.8 ± 5.4 mmHg; P = 0.042). Survival in the sham control and hemorrhagic shock group was 9 of 9, respectively, and 3 of 10 after hemorrhagic shock and stomach inflation (P < 0.001). Conclusions: During hemorrhagic shock stomach inflation caused an abdominal compartment syndrome and thereby impaired cardiopulmonary function and aerobic metabolism, and increased mortality. Subsequent stomach evacuation partly reversed adverse stomach-inflation triggered effects.

Effects of head-up vs. supine CPR on cerebral oxygenation and cerebral metabolism – a prospective, randomized porcine study

BACKGROUND Recent studies have shown that during cardiopulmonary resuscitation (CPR) head-up position (HUP) as compared to standard supine position (SUP) decreases intracranial pressure (ICP) and increases cerebral perfusion pressure (CPP). The impact of this manoeuvre on brain oxygenation and metabolism is not clear. We therefore investigated HUP as compared to SUP during basic life support (BLS) CPR for their effect on brain oxygenation and metabolism. METHODS Twenty pigs were anaesthetized and instrumented. After 8 min of cardiac arrest (CA) pigs were randomized to either HUP or SUP and resuscitated mechanically for 20 min. Mean arterial pressure (MAP), ICP, CPP, cerebral regional oxygen saturation (rSO2) and brain tissue oxygen tension (PbtO2) were measured at baseline, after CA and every 5 min during CPR. Cerebral venous oxygen saturation (ScvO2) was measured at baseline, after CA and after 20 min of CPR. Cerebral microdialysis parameters, e.g. lactate/pyruvate ratio (L/P ratio) were taken at baseline and the end of the experiment. RESULTS ICP was significantly lower in HUP compared to SUP animals after 5 min (18.0 ± 4.5 vs. 24.1 ± 5.2 mmHg; p = 0.033) and 20 min (12.0 ± 3.4 vs. 17.8 ± 4.3 mmHg; p = 0.023) of CPR. Accordingly, CPP was significantly higher in the HUP group after 5 min (11.2 ± 9.5 vs. 1.0 ± 9.2 mmHg; p = 0.045) and 20 min (3.4 ± 6.4 vs. -3.8 ± 2.8 mmHg; p = 0.023) of CPR. However, no difference was found in rSO2, PbtO2, ScvO2 and L/P ratio between groups after 20 min of CPR. CONCLUSION In this animal model of BLS CPR, HUP as compared to SUP did not improve cerebral oxygenation or metabolism.

Beware of etomidate and cricoid pressure during rapid sequence induction

Dear Editor, We read with interest the article of Jaber et al. [1] describing the intensive care unit implementation of a ten-point care bundle for endotracheal intubation in critically ill patients. This care bundle decreased the rate of life-threatening events, including severe hypoxaemia and haemodynamic collapse, from 34 to 21%. Also, minor complications decreased from 21 to 9%. While this care bundle for the high-risk procedure of endotracheal intubation is to be applauded, two points should be critically evaluated. First, the care bundle comprises the administration of etomidate as a firstline hypnotic in haemodynamically unstable patients. However, recent studies suggest that etomidate may increase mortality in critically ill paediatric and adult patients, because it inhibits vital steroid genesis even after a single administration [2, 3]. Thus, another anaesthesia induction with less cardiocirculatory depression may be more suitable in haemodynamically unstable patients. For example, propofol co-induction with 0.1 mg/kg midazolam [4] or 0.5 mg/ kg ketamine [5] is propofol sparing and results in less cardiocirculatory depression than propofol given as a single hypnotic. Second, during anaesthesia rapid sequence induction cricoid pressure has been a standard procedure in airway management to prevent reflux of gastric content. Recently, several studies have showed that it does not compress the oesophagus [6], does not prevent aspiration and may even increase gastric reflux [7]. In addition, bag-valve-mask ventilation, laryngoscopy and tracheal intubation may be hindered [8]. Thus, applying cricoid pressure in emergencies cannot be generally recommended. In conclusion, in the intensive care unit, a care bundle for endotracheal intubation should be applied; however, administration of etomidate and employing cricoid pressure should be critically evaluated.