International guidelines for cardiopulmonary resuscitation (CPR) in adults advocate that cardiac arrest be recognized, within 5-10 s, by the absence of a pulse in the carotid arteries. However, validation of first responders' assessment of the carotid pulse has begun only recently. We aimed (1) to develop a methodology to Study diagnostic accuracy in detecting the presence or absence of the carotid pulse in unresponsive patients, and (2) to evaluate diagnostic accuracy and time required by first responders; to assess the carotid pulse. In 16 patients undergoing coronary artery bypass grafting, four groups of first responders (EMT-1: 107 laypersons with basic life support (BLS) training; EMT-2: 16 emergency medical technicians (EMTs) in training; PM-1: 74 paramedics in training; PM-2: 9 certified paramedics) performed, single-blinded and randomly allocated, carotid pulse assessment either during spontaneous circulation, or during non-pulsatile cardiopulmonary bypass. Time to diagnosis of carotid pulse status, concurrent haemodynamics and diagnostic accuracy were recorded. In 10% (6/59), an absent carotid pulse was not recognized as pulselessness. In 45% (66/147), a pulse was not identified despite a carotid pulse with a systolic pressure ≤ 80 mmHg. Thus, although sensitivity of all participants for central pulselessness approached 90%, specificity was only 55%. Both sensitivity and, to a lesser degree, specificity improved with increasing training; blood pressure or heart rate had no significant effect. The median diagnostic delay was 24 s (minimum 3 s). When no carotid pulse was found, delays were significantly longer (30 s; minimum 13 s), than when a carotid pulse was identified (15 s; minimum 3 s) (P < 0.0001). Of all participants, only 15% (31/206) produced correct diagnoses within 10 s. Only 1/59 (2%) identified pulselessness correctly within 10 s. Our cardiopulmonary bypass model of carotid pulse assessment proved to be feasible and realistic. We conclude that recognition of pulselessness by rescuers with basic CPR training is time-consuming and inaccurate. Both intensive retraining of professional rescuers and reconsideration of guidelines about carotid pulse assessment are warranted.
On the average, 10-15% of patients who undergo cardiopulmonary resuscitation (CPR) following a cardiopulmonary arrest in the hospital environment will survive to be discharged. The purpose of this study was to determine objective factors influencing patient outcome after CPR to determine who should be resuscitated and when to end CPR efforts. The records of 266 patients who underwent in-hospital CPR over a 3-year period were retrospectively analyzed with regard to age, gender, co-morbid conditions, setting of arrest, duration of resuscitation, initial pH and P(O ) during resuscitation, and outcome of resuscitative efforts. Twenty-four (9%) patients survived to be discharged from hospital. Eighty-seven (33%) patients arrested in the intensive care unit, 77 (29%) on the ward, 91 (34%) in the emergency room, six (2%) in the cardiac catheterization laboratory and five (2%) in the operating room. There was no significant difference in survival based on location of arrest. Factors associated with a poor prognosis included age greater than 60, co-morbid disease (i.e. pneumonia, sepsis, renal failure, heart disease, etc.), an initial P(O ) < 50 mmHg and CPR efforts extending beyond 10 min. Based on this data, guidelines regarding initiation and termination of CPR should be instituted in light of poor outcome in patients over 60 years of age with co-morbid conditions, specifically after 10 min of CPR.
Observers trained in basic life support assessed chest rise in 34 patients who were anaesthetised and paralysed and whose lungs were being mechanically ventilated prior to routine surgery. Making 67 independent assessments, the observers indicated the tidal volume that they considered produced adequate chest rise for resuscitation. The mean tidal volume perceived to be adequate was 384 ml with 95% confidence limits of 362-406 ml. The perceived volumes correlated with the Body Mass Index. Guidelines by various authorities recommend that tidal volumes sufficient to make the chest rise normally should be used during resuscitation. The volumes perceived as adequate by the observers are much lower than the numerical values recommended by the American Heart Association (800-1200 ml). High tidal volumes are associated with an increased risk of gastric regurgitation in patients with an unprotected airway, CO delivery to the lungs is likely to be low during cardiac arrest obviating the need for high tidal volumes. In the light of present knowledge and the findings in this study, we would recommend that resuscitation training manikins are recalibrated to indicate satisfactory ventilation at tidal volumes of 400-600 ml. These volumes should reduce the risk of gastric inflation and permit more chest compressions to be carried out in a minute because the ventilation fraction of the CPR sequence is shorter. Adequate CO elimination should still be assured.
Improved cardiopulmonary circulation with active compression-decompression cardiopulmonary resuscitation (ACD-CPR) has been demonstrated in studies using different animal models and a small number of humans in cardiac arrest (CA). However, prehospital studies have shown both positive and no extra benefit of ACD-CPR on return of spontaneous circulation (ROSC), hospital admission and discharge rates. The aim of our prospective study was to compare standard manual CPR (S-CPR) with ACD-CPR as the initial technique of resuscitating patients with out-of-hospital CA, with respect to survival rates and neurological outcome. Patients with out-of-hospital CA treated by emergency medical services (EMS) personnel were randomly assigned to one of two groups (ACD-CPR versus S-CPR). Time intervals to key measures were documented by means of on-line tape-recording. Neurological outcome was assessed using standard scoring systems (cerebral and overall performance categories (CPC and OPC)). A total of 220 patients (S-CPR, n = 114; ACD-CPR, n = 106) were included in the study in a random order. The treatment groups were similar with respect to age, sex, time interval from collapse to CPR, defibrillation and first adrenaline medication. There was no difference between the ACD group and the standard CPR group in terms of ROSC (50.9% vs. 59.6%), hospital admission (33% vs. 33.3%), hospital discharge (16% vs. 14%), or CPC and OPC (1.82 vs. 2.13 and 2.06 vs. 2.25, respectively). Concerning complications of CPR, there was no difference between the groups. In our two-tiered EMS system with physician-staffed ambulances, ACD-CPR neither improved nor impaired survival rates and neurological prognosis in patients with out-of-hospital cardiac arrest. The new CPR technique did not increase the complications associated with the resuscitation effort.
This study was designed to assess the interference by closed-chest cardiopulmonary resuscitation (CPR) on the ventricular fibrillation (VF) ECG signal in a porcine model of cardiac arrest and to elucidate which variable of VF spectral analysis reflects best myocardial blood flow and resuscitation success during CPR. Fourteen domestic pigs were allocated to receive either 0.4 U/kg vasopressin (n = 7) or 10 ml saline (n = 7) after 4 min of VF and 3 min of. CPR. Using radiolabeled microspheres, myocardial blood flow was determined during CPR before, and 90 s and 5 min after, drug administration. Using spectral analysis of VF, the median frequency, dominant frequency, edge frequency and amplitude of VF were determined simultaneously and before the first defibrillation attempt. Using filters in order to specify frequency ranges, stepwise elimination of mechanical artifacts resulting from CPR revealed that at a frequency bandpass of 4.3-35 Hz, median fibrillation frequency has a sensitivity, specificity, positive and negative predictive value of 100% to differentiate between resuscitated and non-resuscitated animals. The best correlation between myocardial blood Bow and fibrillation frequency was found at a median frequency range of 4.3-35 Hz. We conclude that spectral analysis of VF can provide reliable information relating to successful resuscitation. In this model after elimination of oscillations due to mechanical CPR, median fibrillation frequency best reflects the probability of resuscitation success.
In order to compare the quality of CPR performance after various training methods, training outcome assessment must provide meaningful data and do it in a way that is reliable. Few studies have provided details of their assessment procedures, and even fewer report on whether the measures to evaluate performance are reliable (yielding information consistently over multiple trials), or valid (measuring the outcome intended). Few studies have attempted to replicate assessment methods used by other authors. Conventional skill sheets have not been shown to assess compressions and ventilations reliably and validly. When using an instrumented manikin, skill checklists can be simplified by eliminating qualitative assessment of compressions and ventilations. Using a sample of 171 CPR trainees rated by trained evaluators, we provide details of agreement between two evaluators and use an established statistic (Cronbach's α) to assess the reliability of a 14-item simplified CPR checklist. The level of agreement between two raters was high (Pearson product-moment correlation = 0.87) as was the reliability estimate obtained by Cronbach's α (0.89). As criterion-related evidence of the validity of the CPR checklist to assess CPR performance, a correlation with a five-point subjective overall rating of CPR was estimated (Spearman correlation = 0.92). We urge standardized reporting of CPR training outcomes in order to achieve comparability across studies.
At present there are about 1 million trained cardiopulmonary resuscitation (CPR) rescuers in Sweden. CPR out-of-hospital is initiated about 2000 times a year in Sweden. However, very little is known about the bystanders' experiences and reactions. The aim of this study was to describe bystander-initiated CPR, the circumstances, the bystander and his experiences. All CPR bystanders in Sweden who reported their resuscitation attempts between 1990 and 1994 were approached with a phone interview and a postal questionnaire, resulting in 742 questionnaires. Bystander-initiated CPR most frequently took place in public places such as the street. The rescuer most frequently had problems with mouth-to-mouth ventilation (20%) and vomiting (18%). More than half (53%) of the rescuers experienced CPR without problems. Ninety-two percent of the bystanders had no hesitation because of fear of contracting the acquired immunodeficiency syndrome (AIDS) virus. Ninety-three percent of the rescuers regarded their intervention as a mainly positive experience. Of 425 interviewed rescuers, 99.5% were prepared to start CPR again.
1 This study investigates the effects of the non-selective ET(A)/ET(B) receptor antagonist, SE 209670, on systemic haemodynamics, renal function, liver function, acid-base balance and survival in a rat model of endotoxic shock. 2 Injection of E. coli lipopolysaccharide (LPS, 10 mg kg(-1), i.v.) resulted in increases in the serum levels of tumour necrosis factor-alpha (TNF-alpha, maximum 60 min after LPS), endothelin-l (ET-I; maximum 120 min after LPS), and interferon-gamma (IFN-gamma, maximum 180 min after LPS). 3 Injection of LPS also resulted in a fall in blood pressure from 113 +/- 3 mmHg (time = 0) to 84 +/- 4 mmHg at 360 min (n = 15) as well as a hyporeactivity to the vasoconstrictor responses elicited by noradrenaline (NA, 1 mu g kg(-1), i.v.). Pretreatment of rats with a continuous infusion of SB 209670 (3 mg kg(-1), i.v. bolus + 100 mu g kg(-1), i.v. infusion commencing 15 min prior to LPS) significantly augmented the hypotension as well as the vascular hyporeactivity to NA caused by endotoxaemia. 4 Pretreatment of LPS-rats with SB 209670 (3 mg kg(-1), i.v. bolus given 15 min prior to LPS) or infusion of SE 209670 (bolus dose and infusion as above) resulted in a reduction in 6 h-survival from 71% (control) to 30% and 13%, respectively. 5 Endotoxaemia for 4 h resulted in rises in the serum levels of urea and creatinine (indicators of renal failure), but not in the serum levels of bilirubin, GPT and GOT (indicators of liver dysfunction and/or hepatocellular injury). Pretreatment of LPS-rats with SE 209670 (3 mg kg(-1), i.v. bolus 15 min prior to LPS) significantly augmented the serum levels of creatinine, bilirubin, GPT and GOT caused by endotoxin. In addition, endotoxaemia caused, within 15 min, an acute metabolic acidosis (falls in pH, HCO3- and base excess) which was compensated by hyperventilation (fall in PaCO2). Pretreatment of LPS-rats with SE 209670 (3 mg kg(-1), i.v. bolus) significantly augmented the metabolic acidosis caused by LPS. 6 Thus, the non-selective ET(A)/ET(B) receptor antagonist, SB 209670, augments the degree of (i) hypotension, (ii) vascular hyporeactivity to noradrenaline, (iii) renal dysfunction and (iv) metabolic acidosis caused by endotoxin in the anaesthetized rat. In contrast to rats treated with LPS alone, LPS-rats treated with SE 209670 exhibited liver dysfunction and hepatocellular injury. We propose that the release of endogenous ET-l serves to maintain blood pressure and subsequently organ perfusion in septic shock.
When a cardiac arrest occurs in a non-intensive area of the hospital, the emergency response is not always adequate from the point of view of timeliness and technical quality. The aims of this study were to evaluate an experimental programme to improve the CPR skills of staff operating in non-intensive areas of our general hospital and to test the usefulness of placing automatic external defibrillators (AEDs) within these areas. In the experimental phase, two AEDs were placed in 2 non-intensive wards of our hospital for 8 months. The staff of these wards received specific training in CPR and early defibrillation (CPR-D). The devices were used in 19 cases: for defibrillation in four cases of ventricular fibrillation (VF) (three patients were discharged alive from hospital), and for monitoring three supraventricular arrhythmias, one bradyarrhythmia and 11 cardiac rhythms during critical clinical situations. In the implementation phase, four AEDs were indefinitely assigned to as many non-intensive wards. Periodical CPR-D courses and refresher exercises were run; the cardiology staff co-operated in the maintenance of the AEDs and in the registration of technical and clinical data, In the first period of this phase (9 months), AEDs were utilized in 24 cases by the ward-staff: in nine cases for VF (three patients were discharged alive from hospital) and in 15 cases for other rhythm detection in critical conditions. The number and the quality of these uses seem to confirm the favourable impact of the adoption of a more user-friendly defibrillator, such as an AED. The active co-operation between intensive and non-intensive staff was important to facilitate a quick activation of the chain of survival outside the intensive care units. We conclude that AEDs, which were developed for out-of-hospital use by non-physician operators, are suitable for use inside the hospital as well.
Aim: We decided to evaluate the life situation of the survivors after out-of-hospital cardiopulmonary resuscitation (CPR). Method: CPR survivors who were 75 years or younger at the time and who were discharged alive from the hospital were identified consecutively. Average follow-up time was 25.5 months, and at follow-up 24% were deceased and 9% were lost. A questionnaire was completed by 93% and 71% were positive to an interview. Results: Cognitive functions were reduced as well as capacity to perform activities in daily living. This resulted in dependence on other persons for living (nursing homes) and a low return to work. Social isolation was a common complaint. The survivors also reported lower pain awareness than the reference population. As far as other aspects of health-related quality of life, this small group show many similarities with previously evaluated post-infarction patients. Conclusion: Lower pain awareness should be taken into consideration when the CPR patients have ischemic heart disease. If possible, try to prevent social isolation.
Background: diagnosis of precipitating myocardial infarction is essential for management of victims of out-of-hospital cardiac arrest, since investigations and treatment are determined by the underlying cause. Skeletal muscle and myocardial damage from external cardiac massage and defibrillation may complicate biochemical diagnosis of myocardial infarction. Objectives: (a) to examine the relationship between cumulative defibrillation energy and serum levels of cardiac troponin T and MB creatine kinase (MB-CK) mass in out-of-hospital cardiac arrest survivors without electrocardiographic evidence of myocardial infarction; (b) to reassess diagnostic thresholds for myocardial infarction using MB-CK mass and troponin T in this setting. Methods: 77 victims of out-of-hospital cardiac arrest were studied. Serum was obtained for MB-CK mass, CK and troponin T estimation on the first 4 days of admission. Patients were divided into three groups using electrocardiographic criteria: group 1, myocardial infarction; group 2, no evidence of infarction; and group 3, equivocal electrocardiograms. Correlation coefficients were calculated for highest recorded levels of the biochemical markers versus defibrillation energy. Receiver-operating characteristic plots were used to determine optimum biochemical diagnostic thresholds for subjects in groups 1 and 2. Results: using predefined criteria, 27 patients had myocardial infarction, 34 did not have myocardial infarction and 16 had equivocal electrocardiograms. Significant correlations were found for defibrillation energy versus log troponin T (r = 0.42, P < 0.05), log MB-CK mass (r = 0.51, P < 0.01) and total CK (r = 0.68, P < 0.001) in group 2. Within groups 1 and 2, MB-CK mass and troponin T provided additional diagnostic value over MB-CK fraction (P < 0.001). Diagnostic accuracy was not improved by adjusting for shock energy. The optimum threshold value was 4 ng/ml for troponin T (sensitivity 88%, specificity 95%), 60 ng/ml for MB-CK mass (sensitivity 88%, specificity 88%) and 8% of total CK for MB-CK fraction (sensitivity 74%, specificity 82%). These values should be interpreted with caution, since this study is limited by the exclusion of patients with uncertain electrocardiographic diagnoses into group 3. Conclusions: Skeletal muscle and myocardial damage occurs in survivors of out-of-hospital cardiac arrest and is related to the duration of resuscitation. This complicates biochemical diagnosis of underlying myocardial infarction. Specific high diagnostic threshold values for MB-CK and troponin T are needed to optimise diagnostic accuracy. The use of MB-CK fraction leads to greater diagnostic error because of the variability of muscle CK release after resuscitation.
The objective of this study was the assessment of out-of-hospital cardiac arrest and the definition of possible predictive factors for final hospital discharge. Out of a database of 89,557 consecutive missions of the Vienna emergency medical system (EMS) during 1990, there were 623 missions due to a collapse of non-traumatic origin: in 374 cases (60.0%) the patients were declared dead without further attempts at resuscitation. The remaining 249 patients were analysed for predictive factors at site. Survival to hospital admission: 109 patients survived to hospital admission (43.7%); by-stander support had a small impact (P < 0.05) on survival to hospital arrival whereas age and gender had no predictive power. Most patients with ventricular tachycardia/fibrillation (VT/VF) survived primarily (69 of 117, i.e. 59.0%). Survival to hospital discharge: 27 patients were discharged from hospital care (10.8%). ECG findings on arrival of the EMS physician at the site proved to be the only powerful predictor for survival: 24 of 117 patients with VT/VF survived compared with only one of 81 with primary asystole, two of 39 with severe bradycardia, and no patient with electromechanical dissociation.
In this retrospective study we report our initial experience with percutaneous venoarterial extracorporeal membrane oxygenation in the emergency treatment of intractable cardiogenic shock or pulseless electrical activity. Between January 1994 and July 1995, percutaneous venoarterial extracorporeal membrane oxygenation was attempted in seven patients (pulseless electrical activity, five patients; cardiogenic shock, two patients). In two of the seven patients, efforts at arterial cannulation resulted in cannula perforation at the level of the iliac artery. In the remaining five patients, percutaneous venoarterial extracorporeal membrane oxygenation could be established and was maintained for 3-84 h. Major bleeding remained a common complication during extracorporeal membrane oxygenation despite the use of heparin-coated bypass circuits and was responsible for death during extracorporeal membrane oxygenation in one patient. The remaining four patients could be weaned from mechanical circulatory support within 24 h, two after surgical interventions (resection of right atrial tumor: heart transplantation), one after thrombolytic therapy. In one patient, cardiac function recovered spontaneously after 6 h on venoarterial extracorporeal membrane oxygenation. Three patients were discharged from hospital, two of them made a full recovery, one sustained severe hypoxic brain injury. A few patients with intractable cardiogenic shock or pulseless electrical activity can be resuscitated with the help of emergency percutaneous venoarterial extracorporeal membrane oxygenation. Emergency venoarterial extracorporeal membrane oxygenation is associated with a high rate of complications and its use should therefore be limited to selected patients with a rapidly correctable underlying cardiopulmonary pathology (anatomic, metabolic or hypothermic) who do not respond to conventional advanced cardiac life support.
Firm myocardium in cardiopulmonary resuscitation (CPR) is a rarely described yet potentially important condition. To investigate the clinical nature and implications of firm myocardium in CPR, we retrospectively analyzed 59 adult patients with nontraumatic out-of-hospital cardiac arrest who underwent open-chest CPR in the emergency department and had heart consistency recorded. Consistency of the myocardium varied considerably between patients. Firm myocardium was noticed in 36 cases, mainly in the left ventricle (firm myocardium group). The remaining 23 hearts were not firm (soft myocardium group). Some hearts had an increase in their consistency during CPR. Patient characteristics were similar in the two groups. The firm myocardium group showed greater base deficit on arterial blood gas analysis, suggesting more severe ischemic injury. Very firm heart had a close association with an extremely low end-tidal CO tension. Histopathological examination revealed hypertrophy and fibrosis common to the two groups. Both groups received similar treatment except for a shorter duration of direct cardiac massage in the firm myocardium group, although a reasonably prolonged effort was made in most cases. The firm myocardium group responded poorly to treatment. Very firm myocardium never contracted, whereas less firm myocardium usually showed some, albeit insufficient, activity. Most cases in the soft myocardium group regained a pulse: Our results suggest that firm myocardium: (1) is common in patients who receive CPR in the emergency department, (2) indicates ischemic contracture, (3) is not uniform in firmness, reflecting the degree of ischemia and (4) is a grave prognostic factor in cardiac resuscitation.
Asystole in avalanche victims is generally due to asphyxia and not primarily to hypothermia. Hence, on-site establishment of death by asphyxiation would avoid evacuation risks to the rescue party, as well as high costs of transport to, and treatment at, frequently distant specialist centres in cases with a hopeless prognosis. This paper presents a novel differential diagnostic scheme based on burial duration (critical time 45 min) and core temperature (critical level 32°C) of the person on extrication, as well as the presence or absence of an air pocket, facilitating on-site identification of asphyxiated victims. When information regarding an air pocket is uncertain in victims buried longer than 45 min, determination of serum potassium (critical level 10 mmol/l) at the nearest hospital becomes an alternative criterion for triage. The proposed guidelines aim to clarify field decision-making for the emergency doctor with respect to discontinuation of resuscitation and limitation of transferral for cardiopulmonary bypass core rewarming to those patients with presumptive reversible hypothermia.