Do we hyperventilate cardiac arrest patients?

INTRODUCTION: Hyperventilation during cardiopulmonary resuscitation is detrimental to survival. Several clinical studies of ventilation during hospital and out-of-hospital cardiac arrest have demonstrated respiratory rates far in excess of the 10 min(-1) recommended by the ERC. We observed detailed ventilation variables prospectively during manual ventilation of 12 cardiac arrest patients treated in the emergency department of a UK Hospital. METHODS: Adult cardiac arrest patients were treated according to ERC guidelines. Ventilation was provided using a self-inflating bag. A COSMOplus monitor (Respironics Inc.) was inserted into the ventilation circuit at the beginning of the resuscitation from which ventilation data were downloaded to a laptop. RESULTS: Data were collected from 12 patients (7 male; age 47-82 years). The maximum respiratory rate was 9-41 breaths per minute (median 26). The median tidal volume was 619 ml (374-923 ml) and the median respiratory rate was 21 min(-1) (7-37 min(-1)). The corresponding median minute volume was 13.0 l/min (4.6-21.3 min(-1)). Median peak inspiratory pressures were 60.6 cmH(2)O (range 46-106). Airway pressure was positive for 95.3% of the respiratory cycle (range 87.9-100%). CONCLUSIONS: Hyperventilation was common, mostly through high respiratory rates rather than excessive tidal volumes. This is the first study to document tidal volumes and airway pressures during resuscitation. The persistently high airway pressures are likely to have a detrimental effect on blood flow during CPR. Guidelines on respiratory rates are well known, but it would appear that in practice they are not being observed.     

Out-of-hospital cardiac arrest: always coronary angiography?

Introduction: Out-of-hospital cardiac arrest (OHCA) remains one of the principle challenges in the setting of critical care medicine and emergency cardiology.

Areas covered: Long-term survival rates even after successful resuscitation are variable but increasing in the recent years; due to the improvement of base and advanced cardiac life support techniques an increasing number of resuscitated patients are admitted to the hospital. Recent data suggested that patients surviving to hospital discharge after OHCA presented long-term outcome similar to patients with ST-elevation myocardial infarction. However, limited and incompletely clear data are available in the literature about the selection and risk stratification of patients to be subjected to coronary angiography, particularly in patients who have unfavorable clinical features in whom procedures may be futile and may affect public reporting of morality. Recently the ESC and AHA addressed appropriate treatments for ST-elevation myocardial infarction (STEMI) patients with out-of-hospital cardiac arrest.

Expert commentary: Immediate coronary intervention in the setting of OHCA appears to be associated with better survival to discharge; the documentation of an occluded coronary artery in medium 25% of patients without signs of STEMI at ECG helps to explain why early angiography can improve outcomes. In the treatment of OHCA we can find some ethical issues; for example a combination of comorbidities with advanced age and prolonged ischemia indicated by severe lactic acidosis may signify a high enough chance of multiorgan failure or anoxic brain injury and where the benefit of coronary reperfusion therapy appears minimal.     

Comparison of myocardial metabolism by using PET after resuscitation between ventricular fibrillation cardiac arrest and asphyxia cardiac arrest北大核心CSCD

Objective To characterize myocardial metabolism using positron emission tomography (PET) in porcine models of ventricular fibrillation cardiac arrest (VFCA) and asphyxiation cardiac arrest (ACA) after resuscitation. Methods Thirty-Two healthy miniature pigs were randomized into two groups. The pigs of VFCA group (a = 16) were subject to programmed electric stimulation to create a ventricular fibrillation cardiac arrest, and the pigs of ACA group (n = 16) were subjected to endotracheal tube clamping to establish a cardiac arrest (CA). Once modeling was established, pigs with CA were left untreated for a period of 8 mm. Two minutes following initiation of cardiopulmonary resuscitation (CPR), defibrillation was attempted until the restoration of spontaneous circulation (ROSC) was achieved or animals died. To assess myocardial metabolism, PET was performed before modeling, 4 hrs and 24hrs after ROSC. To analyze 18F-FDG myocardial uptake in PET, the maximum standardized uptake value (SUV1) was measured. Results ROSC was obtained in 100% of pigs in VFCA group and only 50% in ACA group. The average survival time in VFCA pigs was significantly longer than that in ACA pigs (22. 63 ± 0. 95) hvs. (8. 75 ± 2. 54) h, P <0.01. VFCA pigs had better mean arterial pressure and cardiac output after ROSC than ACA pigs. Myocardial metabolism imaging using PET demonstrated that myocardial metabolism injuries after ACA were more severe and widespread than those after VFCA at 4 hrs and 24hrs after ROSC and SUV> was much higher in VFCA group than that in ACA group [4 h after ROSC: (1.9 ± 0. 3) vs. (1.0 ±0.4), P <0. 01; 24 h after ROSC: (2.4 ±0.6) vs. (1.2±0.5), P <0.01]. Conclusions Compared with VFCA, ACA causes more severe cardiac metabolism dysfunction associated with less successful resuscitation and shorter survival time; therefore they should he treated as different pathological entities.     

Does resuscitation training affect outcome from cardiac arrest?

It is established that basic life support (BLS) is performed inadequately by both nursing and medical staff and that the ability to retain these skills, once trained, is low. In addition, the initial success rate from cardiopulmonary arrest is poor. By implementing the advanced life support (ALS) course and providing frequent updates on resuscitation skills and management, it is expected that cardiac arrest outcome results should improve. This data is from a 4 year audit of in-hospital cardiac arrest within an adult patient group between January 1993 and December 1996. The average return response of all audit forms was 86.5%. The total sample consisted of 367 separate arrests where the initial rhythm was documented as either ventricular fibrillation (VF)/ventricular tachycardia (VT) (58.3%), asystole (21.7%), electromechanical dissociation (EMD) (7.0%) and other (13.0%). Initial success was defined as return of spontaneous circulation (ROSC). This was achieved in 75.0% of all resuscitation attempts. Within the VF/VT group, successful outcome remained consistent over the 4-year period with an ROSC of 85%. Successful outcome remained consistent in the EMD group, however, the number of arrests was small. Within the asystole group, initial survival increased from 47.5% in 1993-1994 to 67.5% in 1995-1996. These results suggest that BLS and ALS training may only have an impact on initial survival from cardiac arrest.     

Improved outcome of extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest – A comparison with that for extracorporeal rescue for in-hospital cardiac arrest

Purpose

The aim was to investigate the effects of extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrest (OHCA) and compare the results with those of in-hospital cardiac arrest (IHCA).

Methods

We analyzed our extracorporeal membrane oxygenation (ECMO) results for patients who received ECPR for OHCA or IHCA in the last 5 years. Pre-arrest, resuscitation, and post-resuscitative data were evaluated.

Results

In the last 5 years, ECPR was used 230 times for OHCA (n = 31) and IHCA (n = 199). The basic demographic data showed significant differences in age, cardiomyopathy, and location of the initial CPR. Duration of ischemia was shorter in the IHCA group (44.4 ± 24.7 min vs. 67.5 ± 30.6 min, p < 0.05). About 50% of each group underwent a further intervention to treat the underlying etiology. ECMO was maintained for a shorter duration in the OHCA patients (61 ± 48 h vs. 94 ± 122 h, p < 0.05). Survival to discharge was similar in the two groups (38.7% for OHCA vs. 31.2% for IHCA, p > 0.05), as was the favorable outcome rate (25.5% for OHCA vs. 25.1% for IHCA, p > 0.05). Survival was acceptable (about 33%) in both groups when the duration of ischemia was no longer than 75 min.

Conclusions

In addition to having a beneficial effect in IHCA, ECPR can lead to survival and a positive neurological outcome in selected OHCA patients after prolonged resuscitation. Our results suggest that further investigation of the use of ECMO in OHCA is warranted.     

Postresuscitation disease after cardiac arrest: a sepsis-like syndrome?

PURPOSE OF REVIEW: Despite advances in cardiac arrest resuscitation, neurologic impairments and other organ dysfunctions cause considerable mortality and morbidity after restoration of spontaneous cardiac activity. The mechanisms underlying this postresuscitation disease probably involve a whole-body ischemia and reperfusion syndrome that triggers a systemic inflammatory response. RECENT FINDINGS: Postresuscitation disease is characterized by high levels of circulating cytokines and adhesion molecules, the presence of plasma endotoxin, and dysregulated leukocyte production of cytokines: a profile similar to that seen in severe sepsis. Transient myocardial dysfunction can occur after resuscitation, mainly as a result of myocardial stunning. However, early successful angioplasty is independently associated with better outcomes after cardiac arrest associated with myocardial infarction. Coagulation abnormalities occur consistently after successful resuscitation, and their severity is associated with mortality. For example, plasma protein C and S activities after successful resuscitation are lower in nonsurvivors than in survivors. Low baseline cortisol levels may be associated with an increased risk of fatal early refractory shock after cardiac arrest, suggesting adrenal dysfunction in these patients. SUMMARY: Postresuscitation abnormalities after cardiac arrest mimic the immunologic and coagulation disorders observed in severe sepsis. This suggests that therapeutic approaches used recently with success in severe sepsis should be investigated in patients successfully resuscitated after cardiac arrest.     

CPR courses and semi-automatic defibrillators--life saving in cardiac arrest?

OBJECTIVES: The aim was to assess the knowledge of life-supporting first-aid in both cardiac arrest survivors and relatives, and their willingness to have a semi-automatic external defibrillator in their homes and use it in an emergency. MATERIAL AND METHODS: Cardiac arrest survivors, their families, friends, neighbours and co-workers were interviewed by medical students using prepared questionnaires. Their knowledge and self-assessment of life-supporting first-aid, their willingness to have a semi-automatic defibrillator in their homes and their willingness to use it in an emergency before and after a course in cardiopulmonary resuscitation (CPR) with a semi-automatic external defibrillator was evaluated. Courses were taught by medical students who had received special training in basic and advanced life support. RESULTS: Both patients and relatives, after a course of 2-3 h, were no longer afraid of making mistakes by providing life-supporting first-aid. The automated external defibrillator (AED) was generally accepted and considered easy to handle. CONCLUSION: We consider equipping high-risk patients and their families with AEDs as a viable method of increasing their survival in case of a recurring cardiac arrest. This, of course, should be corroborated by further studies.     

Monitoring during cardiac arrest: are we there yet?

Advancements in electronic data acquisition have translated into improved monitoring of victims of cardiac arrest, but initial techniques remain direct observation of pulses and respirations. The most essential monitor continues to be the electrocardiogram. However, monitoring diastolic blood pressure, myocardial perfusion pressure, and end-tidal carbon dioxide are extremely useful. Most of the current research on monitoring during cardiopulmonary resuscitation focuses on methods for analyzing ventricular fibrillation waveforms. By analyzing the waveform, defibrillation shocks may be delivered at the time when the chance of success is optimal. Low-amplitude and low-frequency fibrillation waveforms are associated with increased rates of asystole and pulseless electrical activity after defibrillation. Methods of analyzing the ventricular fibrillation waveform include measuring the amplitude and frequency and combining the contributions of amplitude and frequency by various methods to improve discrimination. Other types of monitoring being studied for their usefulness during cardiac arrests include sonography, Bispectral Index monitoring, tissue carbon dioxide monitors, and pupil observation. The test of these monitoring techniques is ultimately their ability to improve patient survival to hospital discharge, which is a major challenge for resuscitation researchers.