Marc Freysz

Could heart rate variability predict outcome in patients with severe head injury? A pilot study.

Despite major improvements in the resuscitation of patients with head injury, the outcome of patients with head trauma often remains poor and difficult to establish. Heart rate variability (HRV) analysis is a noninvasive tool used to measure autonomic nervous system (ANS) activity. The aim of this prospective study was to investigate whether HRV analysis might be a useful adjunct for predicting outcome in patients with severe head injury. Twenty patients with severe head trauma (Glasgow Coma Scale [GCS] ≤ 8) underwent 24-hour electrocardiogram recording 1 day after trauma and again 48 hours after withdrawal of sedative drugs. Heart rate variability was assessed, in both time domain and spectral domain. The authors initially compared (on Day 1) HRV in patients who progressed to brain death to HRV in survivors; then during the awakening period compared HRV in surviving patients with good recovery (GCS ≥ 10) to HRV in patients characterized by a worsened neurologic state (GCS < 10). Statistical analysis used the Kruskal-Wallis test, P < .05. To assess whether HRV could predict evolution to brain death, receiver operating characteristic (ROC) curves were generated the day after trauma for Total Power, natural logarithm of high-frequency component of spectral analysis (LnHF), natural logarithm of low-frequency component of spectral analysis (LnLF), and root mean square for successive interval differences (rMSSD). Seven patients died between Day 1 and Day 5 after trauma. Six of those had progressed to brain death. In these six patients, at Day 1, Global HRV and parasympathetic tone were significantly higher. Referring to the area under the rMSSD ROC curve, HRV might provide useful information in predicting early evolution of patients with severe head trauma. During the awakening period, global HRV and the parasympathetic tone were significantly lower in the worsened neurologic state group. In conclusion, HRV could be helpful as a predictor of imminent brain death and a useful adjunct for predicting the outcome of patients with severe head injury.

Decrease in the Stroke Case Fatality Rates in a French Population-Based Twenty-Year Study

Background: The aim of the study was to estimate trends in stroke case fatality in a French population-based study over the last 20 years, and to compare trends in men and women. Methods: We prospectively ascertained first-ever strokes in a well-defined population-based study, from 1985 to 2004, in Dijon (France) (150,000 inhabitants). The study was both specific and exhaustive. The follow-up made it possible to analyze case fatality, according to stroke subtypes and sex. Results: From the ascertainment of 3,691 strokes divided in 1,920 cerebral infarcts from large artery atheroma, 725 cerebral infarcts from small perforating artery atheroma, 497 cardioembolic infarcts, 134 cerebral infarcts from undetermined mechanism, 341 primary cerebral hemorrhages and 74 subarachnoïd hemorrhages, we observed a significant decrease in 28-day case fatality rates of almost 25% (p = 0.03). Case fatality rates decreased in men aged >75 years (p = 0.01) and in women aged >75 years (p = 0.02) and >65 years (p = 0.03). The magnitude of the decrease was smaller in women but not significantly so. According to stroke subtypes, case fatality rates significantly decreased for small perforating artery infarct (p = 0.04) and for primary cerebral hemorrhage (p = 0.03). In multivariate regression analyses, hemorrhagic stroke, the first period of the study (1985–1989), blood hypertension, previous myocardial infarction and age <85 years had a negative effect. Conclusion: This is the first population-based study using continuous ascertainment over a period of 20 years that has demonstrated a significant reduction in case fatality rates. We did not observe any significant differences between men and women.

Could heart rate variability analysis become an early predictor of imminent brain death? A pilot study

UNLABELLED Physiology of brain death is characterized by major disturbances of autonomic nervous system (ANS) activity which can lead to graft dysfunction. These findings exhibit the importance of early diagnosis of brain death to improve transplantation outcome. The aim of this prospective study was to assess whether heart rate variability (HRV) analysis, a noninvasive method to investigate ANS activity in comatose patients, could achieve this goal. A total of 14 brain-injured patients were included in the study as soon as they exhibited the clinical signs of imminent brain death. The electrocardiogram was then recorded from two leads with a Holter digital monitor. The clinical diagnosis of brain death was considered after an autonomic storm had occurred. HRV was assessed from 6 h before to 6 h after brain death in both time domain and spectral analysis, estimating either global ANS activity (index of variability, total power), parasympathetic activity (percentage of delta of R-R interval >50 ms, root mean square for successive interval differences, LnHF) or sympathetic activity (LnLF). Hourly averages of these variables were compared by using one-way analysis of variance. To assess whether HRV could per se diagnose brain death, receiver operating characteristic curves were generated for total power, root mean square for successive interval differences, and LnHF. We observed, for 6 h before brain death, a progressive extinction of the influence of the ANS on cardiovascular regulation. There was no activity in the two components of the ANS as soon as brain death occurred. HRV analysis appeared to be a very sensitive but a less specific method of diagnosing brain death. IMPLICATIONS A total of 14 brain-injured patients with the clinical criteria of imminent brain death were enrolled for electrocardiogram recording and heart rate variability analysis (a noninvasive method to investigate autonomic nervous system activity). For 6 h before brain death, we observed a progressive extinction of autonomic nervous system activity which was not present as soon as brain death was clinically evoked.

Benefits of computer screen-based simulation in learning cardiac arrest procedures

Medical Education 2010: 44: 716–722

Does the prognosis of cardiac arrest differ in trauma patients

Objective:It is proposed to not resuscitate trauma patients who have a cardiac arrest outside the hospital because they are assumed to have a dismal prognosis. Our aim was to compare the outcome of patients with traumatic or nontraumatic (“medical”) out-of-hospital cardiac arrest. Design:Cohort analysis of patients with out-of-hospital cardiac arrest included in the European Epinephrine Study Group’s trial comparing high vs. standard doses of epinephrine. Setting:Nine French university hospitals. Patients:A total of 2,910 patients. Interventions:Patients were successively and randomly assigned to receive repeated high doses (5 mg each) or standard doses (1 mg each) of epinephrine at 3-min intervals. Measurements and Main Results:Return of spontaneous circulation, survival to hospital admission and discharge, and secondary outcome measures of 1-yr survival and neurologic outcome were recorded. In the trauma group, patients were younger (42 ± 17 vs. 62 ± 17 yrs, p < .001), presented with fewer witnessed out-of-hospital cardiac arrests (62.3% vs. 79.7%), and had fewer instances of ventricular fibrillation as the first documented pulseless rhythm (3.4% [95% confidence interval, 1.2–5.5%] vs. 17.3% [15.8–18.7%]). A return of spontaneous circulation was observed in 91 of 268 trauma patients (34.0% [28.3–39.6%]) compared with 797 of 2,642 medical patients (30.2% [28.4–31.9%]), and more trauma patients survived to be admitted to the hospital (29.9% [24.4–35.3%] vs. 23.5% [22.0–25.2%]). However, there was no significant difference between trauma and medical groups at hospital discharge (2.2% [0.5–4.0%] vs. 2.8% [2.1–3.4%]) and 1-yr survival (1.9% [0.3–3.5%] vs. 2.5% [1.9–3.1%]). Among patients who were discharged, a good neurologic status was observed in two trauma patients (33.3% [4.3–77.7%]) and 37 medical patients (50% [38.1–61.9%]). Conclusions:The survival and neurologic outcome of out-of-hospital cardiac arrest were not different between trauma and medical patients. This result suggests that, under the supervision of senior physicians, active resuscitation after out-of-hospital cardiac arrest is as important in trauma as in medical patients.

Impact of emergency medical helicopter transport directly to a university hospital trauma center on mortality of severe blunt trauma patients until discharge

IntroductionThe benefits of transporting severely injured patients by helicopter remain controversial. This study aimed to analyze the impact on mortality of helicopter compared to ground transport directly from the scene to a University hospital trauma center.MethodsThe French Intensive Care Research for Severe Trauma cohort study enrolled 2,703 patients with severe blunt trauma requiring admission to University hospital intensive care units within 72 hours. Pre-hospital and hospital clinical data, including the mode of transport, (helicopter (HMICU) versus ground (GMICU), both with medical teams), were recorded. The analysis was restricted to patients admitted directly from the scene to a University hospital trauma center. The main endpoint was mortality until ICU discharge.ResultsOf the 1,958 patients analyzed, 74% were transported by GMICU, 26% by HMICU. Median injury severity score (ISS) was 26 (interquartile range (IQR) 19 to 34) for HMICU patients and 25 (IQR 18 to 34) for GMICU patients. Compared to GMICU, HMICU patients had a higher median time frame before hospital admission and were more intensively treated in the pre-hospital phase. Crude mortality until hospital discharge was the same regardless of pre-hospital mode of transport. After adjustment for initial status, the risk of death was significantly lower (odds ratio (OR): 0.68, 95% confidence interval (CI) 0.47 to 0.98, P = 0.035) for HMICU compared with GMICU. This result did not change after further adjustment for ISS and overall surgical procedures.ConclusionsThis study suggests a beneficial impact of helicopter transport on mortality in severe blunt trauma. Whether this association could be due to better management in the pre-hospital phase needs to be more thoroughly assessed.

Beneficial effects of direct call to emergency medical services in acute myocardial infarction.

Objectives: We investigated the impact of an emergency medical services call on the management of acute myocardial infarction, considering time intervals for intervention and revascularization procedures. Methods: Data were prospectively collected from January 2001 to October 2002 from 531 patients hospitalized for myocardial infarction with ST segment elevation and a pre-hospital delay of less than 24 h. Results: Only 26% of patients called the emergency medical services at the onset of symptoms (n=140). Other patients (n=391, 74%) called another medical contact. Baseline characteristics and cardiovascular history were similar in the two groups, except for the percutaneous coronary intervention history (10% in the emergency medical services group versus 4% in the other medical contact group, P<0.05). Time intervals from the onset of symptoms of myocardial infarction to call or to medical intervention, as well as the time interval from medical intervention to hospital admission were significantly shorter in the emergency medical services group. The early reperfusion rate was also significantly greater in the emergency medical services group (77%) compared with the other medical contact group (64%), mainly because of a greater incidence of primary percutaneous coronary intervention (36 versus 26%, P<0.03, respectively). Multivariate analysis adjusted for sex and age showed that less than three medical care providers [odds ratio (OR) 5.042, P<0.001], percutaneous coronary intervention history (OR 2.462, P<0.05), as well as rhythmic disorders (OR 2.105, P<0.05) and complete atrioventricular block (OR 2.757, P<0.05) were independent predictors of emergency medical services care. Conclusion: This study demonstrated that a call to the emergency medical services is underutilized by patients with symptoms of myocardial infarction, and documented the beneficial effects of an emergency medical services call by reducing pre-hospital delays and increasing early revascularization therapies.

In vivo and in vitro antioxidant properties of furosemide.

The aim of this study was to investigate in vivo and in vitro antioxidant properties of furosemide. In vitro, human red blood cells were submitted to oxidative stress (AAPH), in absence or in presence of different concentrations of furosemide. Potassium efflux was measured in order to quantify the oxidative stress after the action of AAPH on red blood cells. Allophycocyanin assay was also used to investigate antioxidant capacities of furosemide. For the in vivo experiment, male Wistar rats were used. A control group (n = 5) was treated by a daily intraperitoneal injection of saline solution (0.2 ml); 2 other groups (J0 and J+) were treated for 7 days by one daily intraperitoneal injection of furosemide (0.10 mg/kg/day). In the J+group, the injection of furosemide was done one hour before the experiment, while in the J0 group the last injection of furosemide was done on the 6th day and an injection of saline was performed one hour before the experiment. On the day of experiment, a laparotomy was performed under general anesthesia and blood was collected from abdominal aorta. Oxidative stress and antioxidant capacities were evaluated on Wistar rat red blood cells and plasma. In vitro results (oxidative challenge with AAPH) showed that oxidative stress was decreased in presence of furosemide. This was due to a potent free radical scavenging effect of furosemide. In vivo studies confirmed that furosemide had antioxidant properties. These data may be of great relevance in clinical practice, considering the use of large doses of furosemide in patients presenting pathology involving the production of free radicals.

Comparison of two techniques for retrograde tracheal intubation in human fresh cadavers.

Background:During retrograde tracheal intubation, the short distance existing between the cricothyroid membrane and vocal cords may be responsible for accidental extubation. The insertion of a catheter into the trachea before the removal of the guide wire may help to cope with this problem. This work was conducted to study the impact of such a modification on the success rate and the duration of the procedure. Methods:Procedures of retrograde tracheal intubation following the classic and modified techniques were randomly performed in cadavers (n = 70). The duration of the procedure from the puncture of the cricothyroid membrane to the inflation of the balloon of the endotracheal tube was measured, and, at the end of the procedure, the position of the endotracheal tube was checked under laryngoscopy. The procedure was considered to have failed if it had taken more than 5 min or when the endotracheal tube was not positioned in the trachea. Results:The mean time to achieve tracheal intubation was similar in both groups (123 ± 51 vs. 127 ± 41 s; not significant), but intubation failed significantly more frequently with the classic technique (22 vs. 8 failures; P < 0.05). All failures were related to incorrect positioning of the endotracheal tube. In four cases, both techniques failed. Conclusions:This efficient, simple modification of the technique significantly increases the success rate of the procedure, without prolonging its duration. These data should be confirmed in clinical conditions but may encourage a larger use of the retrograde technique in cases of difficult intubation.

The motor component does not convey all the mortality prediction capacity of the Glasgow Coma Scale in trauma patients

PURPOSE We tested the hypothesis that the motor component of the Glasgow Coma Scale (GCS) conveys most of the predictive information of triage scores (Triage Revised Trauma Score [T-RTS] and the Mechanism, GCS, Age, arterial Pressure score [MGAP]) in trauma patients. METHOD We conducted a multicenter prospective observational study and evaluated 1690 trauma patients in 14 centers. We compared the GCS, T-RTS, MGAP, and Trauma Related Injury Severity Score (reference standard) using the full GCS or its motor component only using logistic regression model, area under the receiver operating characteristic curve, and reclassification technique. RESULTS Although some changes were noted for the GCS itself and the Trauma Related Injury Severity Score, no significant change was observed using the motor component only for T-RTS and MGAP when considering (1) the odds ratio of variables included in the logistic model as well as their discrimination and calibration characteristics, (2) the area under the receiver operating characteristic curve (0.827 ± 0.014 vs 0.831 ± 0.014, P = .31 and 0.863 ± 0.011 vs 0.859 ± 0.012, P = .23, respectively), and (3) the reclassification technique. Although the mortality rate remained less than the predetermined threshold of 5% in the low-risk stratum, it slightly increased for MGAP (from 1.9% to 3.9%, P = .048). CONCLUSION The use of the motor component only of the GCS did not change the global performance of triage scores in trauma patients. However, because a subtle increase in mortality rate was observed in the low-risk stratum for MGAP, replacing the GCS by its motor component may not be recommended in every situation.