Chest compressions versus ventilation plus chest compressions: a randomized trial in a pediatric asphyxial cardiac arrest animal model

Purpose  

To compare survival, oxygenation, ventilation, and hemodynamic variables achieved with chest compressions or ventilation plus chest compressions.     

Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study

Introduction

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions.

Methods

The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling.

Results

There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13–50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device.

Conclusions

The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions.     

Passive continuous positive airway pressure ventilation during cardiopulmonary resuscitation: a randomized cross-over manikin simulation study

While controlled ventilation is most frequently used during cardiopulmonary resuscitation (CPR), the application of continuous positive airway pressure (CPAP) and passive ventilation of the lung synchronously with chest compressions and decompressions might represent a promising alternative approach. One benefit of CPAP during CPR is the reduction of peak airway pressures and therefore a potential enhancement in haemodynamics. We therefore evaluated the tidal volumes and airway pressures achieved during CPAP–CPR. During CPR with the LUCAS? 2 compression device, a manikin model was passively ventilated at CPAP levels of 5, 10, 20 and 30 hPa with the Boussignac tracheal tube and the ventilators Evita^® V500, Medumat^® Transport, Oxylator^® EMX, Oxylog^® 2000, Oxylog^® 3000, Primus^® and Servo^®-i as well as the Wenoll^® diver rescue system. Tidal volumes and airway pressures during CPAP–CPR were recorded and analyzed. Tidal volumes during CPAP–CPR were higher than during compression-only CPR without positive airway pressure. The passively generated tidal volumes increased with increasing CPAP levels and were significantly influenced by the ventilators used. During ventilation at 20 hPa CPAP via a tracheal tube, the mean tidal volumes ranged from 125 ml (Medumat^®) to 309 ml (Wenoll^®) and the peak airway pressures from 23 hPa (Primus^®) to 49 hPa (Oxylog^® 3000). Transport ventilators generated lower tidal volumes than intensive care ventilators or closed-circuit systems. Peak airway pressures during CPAP–CPR were lower than those during controlled ventilation CPR reported in literature. High peak airway pressures are known to limit the applicability of ventilation via facemask or via supraglottic airway devices and may adversely affect haemodynamics. Hence, the application of ventilators generating high tidal volumes with low peak airway pressures appears desirable during CPAP–CPR. The limited CPAP–CPR capabilities of transport ventilators in our study might be prerequisite for future developments of transport ventilators.     

Chest compressions by ambulance personnel on chests with variable stiffness: abilities and attitudes

INTRODUCTION: Quality of cardiopulmonary resuscitation (CPR) performed by professionals is reported to be substandard even with automated corrective feedback. We hypothesised that lack of quality is not due to physical capabilities. MATERIALS AND METHODS: Eighty ambulance personnel from the same services where the quality of clinical CPR was investigated, performed two-rescuer CPR with similar corrective feedback for 5min on each of four manikins with different chest stiffness. The personnel also scored their agreement with statements on clinical CPR performance. RESULTS: All study subjects performed CPR well within Guidelines recommendations on all four manikins with mean compression depth 44+/-3mm, compression rate 101+/-3min(-1), and 7+/-2 ventilations per minute. Three quarters stated that during CPR on patients their personal sense of correct depth and force determined their performance. Fifty-five percent believed that too deep chest compressions could cause serious injury to the patient, and 39% that compressing to Guidelines recommended depth may often result in severe patient injury. A quarter felt that the potential benefits of compressing to the Guidelines depth could not justify the injuries it would cause. Breaking ribs made 54% feel very uncomfortable. CONCLUSIONS: Ambulance personnel were physically capable of consistently compressing to the Guidelines depth even on the stiffest chest. These laboratory results cannot be directly compared to the clinical out-of-hospital ALS situation, but strongly indicate that the inadequate chest compressions found in our clinical study were not due to lack of physical capability. We speculate that this may at least partly be explained by their fear of causing patient injury and trust in their own opinion of what is the correct compression depth and force in preference to the feedback.     

Ultrasound-assisted paracentesis performed by emergency physicians vs the traditional technique: a prospective, randomized study

STUDY OBJECTIVE: To determine if emergency center ultrasound (ECUS) can be of value to emergency physicians in the evaluation of possible ascites and accompanying decisions to perform emergent paracentesis. METHODS: During a 7-month period, patients suspected of having ascites and potentially requiring paracentesis were prospectively entered into a randomized study in an urban public hospital emergency center (>140 000 annual visits). Patients were randomized to receive paracentesis using the traditional or the bedside ECUS-assisted technique. Indications for paracentesis included known liver disease and obvious ascites as well as suspected ascites or suspected subacute bacterial peritonitis. Participating physicians had received a minimum of 1 hour of formal didactic ultrasound training that included gallbladder, renal, vascular, and bladder studies as well as the focused abdominal sonography for trauma examination for trauma and the detection of ascites. A portable Terason 2000 laptop ultrasound machine with a 5-MHz probe was used to scan the patients. Data collected included the patients' characteristics, estimation of ascitic fluid volume, number of attempts made to obtain fluid, speed of paracentesis, and the operator's overall evaluation of the ECUS-assisted technique, if used. RESULTS: Of 100 enrolled patients, 56 received the ECUS-assisted technique. Of 42 patients with ascites, 40 (95%) were successfully aspirated and 14 (25%) did not receive paracentesis because no ascites or insignificant amount of ascites was visualized. One patient was noted to have a large cystic mass in the left lower quadrant and another patient had a ventral hernia. Of the 44 patients randomized to the traditional technique, 27 (61%) were successfully aspirated. In 17 (39%) of these patients, fluid could not be obtained using traditional methods. Of these 17 failed attempts by traditional methods, 15 patients received ECUS in a "break" from the study protocol. Ascitic fluid was obtained in 13 of these 15 patients; of the 2 remaining patients, 1 did not have enough fluid to be sampled and the other had no fluid visualized. CONCLUSION: Ninety-five percent (P=.0003) of the patients who were randomized in the ECUS group and in whom a needle paracentesis was performed had ascitic fluid successfully obtained, as compared with the traditional method group.     

心肺复苏时佩戴N95口罩对胸外按压质量的影响

目的 评估医务人员佩戴N95 口罩进行心肺复苏(cardiopulmonary resuscitation,CPR)对胸外按压质量及疲劳情况的影响.方法 纳入武汉大学中南医院近两年内获得美国心脏协会基础生命支持认证的医护人员80名,复习按压要点并熟悉模型后,通过随机数字法分为两组:佩戴外科口罩组(SM组),佩戴N95 ...     

A randomized cross-over study comparing surgical cricothyrotomy techniques by combat medics using a synthetic cadaver model

Objective

Cricothyrotomy is a complex procedure with a high rate of complications including failure to cannulate and injury to adjacent anatomy. The Control-Cric? System and QuickTrach II? represent two novel devices designed to optimize success and minimize complications with this procedure. This study compares these two devices against a standard open surgical technique.

Effect of ascorbic acid on microcirculation in patients with Type II diabetes: a randomized placebo-controlled cross-over study

Manifestations of vascular disease, including microvascular changes, constitute the major part of the morbidity and mortality in diabetic patients. Oxidative stress has been suggested to play an important role in the vascular dysfunction of diabetic patients. Furthermore, epidemiological observations indicate a beneficial effect of an increased dietary intake of antioxidants. The present study tested the hypothesis that the antioxidant ascorbic acid influences microcirculatory function in patients with Type II diabetes. Patients with Type II diabetes were treated with 1 g of ascorbic acid three times a day for 2 weeks in a randomized placebo-controlled double-blind cross-over design. Microvascular reactivity was assessed by vital capillaroscopy and PRH (post-occlusive reactive hyperaemia). hs-CRP (high-sensitivity C-reactive protein), IL-6 (interleukin-6), IL-1ra (interleukin-1 receptor antagonist) and ox-LDL (oxidized low-density lipoprotein) were analysed. The results showed no significant change in microvascular reactivity assessed after 2 weeks of ascorbic acid treatment. TtP (time to peak) was 12.0+/-3.3 s before and 11.2+/-3.5 s after ascorbic acid (n=17). In comparison, TtP was 11.5+/-2.9 s before and 10.6+/-2.8 s after placebo (not significant). IL-1ra, IL-6, hs-CRP and ox-LDL did not change significantly after ascorbic acid, neither as absolute or relative values. In conclusion, in contrast with some studies reported previously, we could not demonstrate an effect of continuous oral treatment with ascorbic acid on microvascular reactivity assessed at the level of individual capillaries. Furthermore, we found no indication of an effect on inflammatory cytokines or ox-LDL.     

Comparative evaluation of three interfaces for non-invasive ventilation: a randomized cross-over design physiologic study on healthy volunteers

Introduction

Interface choice is crucial for non-invasive ventilation (NIV) success. We compared a new interface, the helmet next (H_N), with the facial mask (FM) and the standard helmet (H_S) in twelve healthy volunteers.

Methods

In this study, five NIV trials were randomly applied, preceded and followed by a trial of unassisted spontaneous breathing (SB). Baseline settings, for example, 5 cmH₂O of both inspiratory pressure support (PS) and positive end-expiratory pressure (PEEP), were applied through FM, H_S and H_N, while increased settings (PS and PEEP of 8 cmH₂O) were only applied through H_S and H_N. We measured flow, airway, esophageal and gastric pressures, and calculated inspiratory effort indexes and trigger delays. Comfort was assessed with a visual-analog-scale.

Results

We found that FM, H_S and H_N at baseline settings were not significantly different with respect to inspiratory effort indexes and comfort. Inspiratory trigger delay and time of synchrony (TI,synchrony) were significantly improved by FM compared to both helmets, whereas expiratory trigger delay was shorter with FM, as opposed to H_S only. H_N at increased settings performed better than FM in decreasing inspiratory effort measured by pressure-time product of transdiaphragmatic pressure (PTPdi)/breath (10.7 ± 9.9 versus 17.0 ± 11.0 cmH₂O*s), and PTPdi/min (128 ± 96 versus 204 ± 81 cmH₂O*s/min), and PTPdi/L (12.6 ± 9.9 versus 30.2 ± 16.8 cmH₂O*s/L). TI, synchrony was inferior between H_N and H_S at increased settings and FM.

Conclusions

H_N might hold some advantages with respect to interaction and synchrony between subject and ventilator, but studies on patients are needed to confirm these findings.

Trial registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01610960","term_id":"NCT01610960"}}NCT01610960     

Biological effects of aspirin and clopidogrel in a randomized cross-over study in 96 healthy volunteers

BACKGROUND: Some data suggest that biological 'resistance' to aspirin or clopidogrel may influence clinical outcome. OBJECTIVE: The aim of this study was to evaluate the relationship between aspirin and clopidogrel responsiveness in healthy subjects. METHODS: Ninety-six healthy subjects were randomly assigned to receive a 1-week course of aspirin 100 mg day(-1) followed by a 1-week course of clopidogrel (300 mg on day 1, then 75 mg day(-1)), or the reverse sequence, separated by a 2-week wash-out period. The drug effects were assessed by means of serum TxB2 assay, platelet aggregation tests, and the PFA -100 and Ultegra RPFA -Verify Now methods. RESULTS: Only one subject had true aspirin resistance, defined as a serum TxB2 level > 80 pg microL(-1) at the end of aspirin administration and confirmed by platelet incubation with aspirin. PFA-100 values were normal in 29% of the subjects after aspirin intake, despite a drastic reduction in TxB2 production; these subjects were considered to have aspirin pseudo-resistance. Clopidogrel responsiveness was not related to aspirin pseudo-resistance. Selected polymorphisms of platelet receptor genes were not associated with either aspirin or clopidogrel responsiveness. CONCLUSIONS: In healthy subjects, true aspirin resistance is rare and aspirin pseudo-resistance is not related to clopidogrel responsiveness.     

Advanced life support performance with manual and mechanical chest compressions in a randomized,multicentre manikin study

Aim of the studyClinical mechanical chest compression studies report diverging outcomes. Confounding effects of variability in hands-off fraction (HOF) and timing of necessary tasks during advanced life support (ALS) may contribute to this divergence. Study site variability in these factors coupled to randomization of cardiopulmonary resuscitation (CPR) method was studied during simulated cardiac arrest prior to a multicentre clinical trial.MethodAmbulance personnel from four sites were tested in randomized, simulated cardiac arrest scenarios with manual CPR or load-distributing band CPR (LDB-CPR) on manikins. Primary emphasis was on HOF and time spent before necessary predefined ALS task (ALS milestones). Results are presented as mean differences (confidence interval).ResultsAt the site with lowest HOF during manual CPR, HOF deteriorated with LDB-CPR by 0.06 (0.005, 0.118, p = 0.04), while it improved at the two sites with highest HOF during manual CPR by 0.07 (0.019, 0.112, p = 0.007) and 0.08 (0.004, 0.165, p = 0.042). Initial defibrillation was 29 (3, 55, p = 0.032) s delayed for LDB-CPR vs. manual CPR. Other ALS milestones trended toward earlier completion with LDB-CPR; only significant for intravenous access, mean difference 70 (24, 115, p = 0.003) s.ConclusionIn this manikin study, HOF for manual vs. mechanical chest compressions varied between sites. Study protocol implementation should be simulation tested before launching multicentre trials, to optimize performance and improve reliability and scientific interpretation.     

Antiemetics in the ED: a randomized controlled trial comparing 3 common agents

We sought to compare the efficacy of 3 intravenous antiemetic medications in ED patients complaining of moderate to severe nausea. This randomized, placebo-controlled, double-blind trial compares 1.25 mg droperidol, 10 mg metoclopramide, 10 mg prochlorperazine, and saline placebo. Adult ED patients complaining of nausea were eligible. Nausea was measured on a 100-mm visual analog scale at 0 and 30 minutes after treatment. A convenience sample of 100 patients was enrolled; 97 had complete data available for analysis. Of these, 22 patients received droperidol, 25 received metoclopramide, 24 received prochlorperazine, and 26 received placebo. Droperidol (-54.5 mm) was significantly better than metoclopramide (-40.2 mm) or prochlorperazine (-40.5 mm) at reducing nausea at 30 minutes (P = .04). There were no significant differences in rescue medication or patient satisfaction; however, droperidol had significantly higher akathisia (71.4% vs 23.5%) at 24-hour follow-up. When administered intravenously to adult patients with moderate to severe nausea, droperidol was more effective than metoclopramide or prochlorperazine but caused more extrapyramidal symptoms. Metoclopramide and prochlorperazine were not more effective than saline placebo. All patients improved over time and possibly with intravenous hydration.