Compression techniques and blood flow during cardiopulmonary resuscitation. A statement for the Advanced Life Support Working Party of the European Resuscitation Council

The impact of manual defibrillation technique on no-flow time during simulated cardiopulmonary resuscitation

INTRODUCTION

Rapid defibrillation is the most effective strategy for establishing return of spontaneous circulation following cardiac arrest due to ventricular fibrillation. The aim of this study is to measure the delay due to of charging the defibrillator during chest compression in an attempt to reduce the duration of the pre-shock pause in between cessation of chest compressions and shock delivery as advocated by the American Heart Association (AHA) guidelines compared to charging the defibrillator immediately following rhythm analysis without resuming chest compressions as recommended by the European Resuscitation Council (ERC).

METHODS

This was a randomised controlled cross over trial comparing pre-shock pause times when defibrillation was performed on a manikin according to the AHA and ERC guidelines using paddles and hands free defibrillation systems.

RESULTS

The pre-shock pause between cessation of chest compression and shock delivery was significantly different between techniques (Friedman test, P<0.0001). ERC paddles technique had the greatest pre-shock pause (7.4 s [6.7-11.2]) followed by ERC hands free (7.0 s [6.5-8.5]) and AHA paddles (1.6 s [1.1-2.3]). AHA hands free took the least amount of time (1.5 s [0.8-1.5]). Extrapolating these data to older defibrillators with longer charge times saw pre-shock pause intervals of 9 s (Codemaster XL) and 12 s (Lifepak 20) with the ERC approach.

CONCLUSION

This study demonstrated clinically significant delays to defibrillation by analysing and charging the defibrillator without performing concurrent chest compressions. In a simulated scenario, charging the defibrillator whilst performing chest compressions was perceived as safe and significantly reduced the pre-shock pause between cessation of chest compression and shock delivery.

Clinical investigation: thyroid function test abnormalities in cardiac arrest associated with acute coronary syndrome

INTRODUCTION

It is known that thyroid homeostasis is altered during the acute phase of cardiac arrest. However, it is not clear under what conditions, how and for how long these alterations occur. In the present study we examined thyroid function tests (TFTs) in the acute phase of cardiac arrest caused by acute coronary syndrome (ACS) and at the end of the first 2 months after the event.

METHOD

Fifty patients with cardiac arrest induced by ACS and 31 patients with acute myocardial infarction (AMI) who did not require cardioversion or cardiopulmonary resuscitation were enrolled in the study, as were 40 healthy volunteers. The patients were divided into three groups based on duration of cardiac arrest (<5 min, 5-10 min and >10 min). Blood samples were collected for thyroid-stimulating hormone (TSH), tri-iodothyronine (T3), free T3, thyroxine (T4), free T4, troponin-I and creatine kinase-MB measurements. The blood samples for TFTs were taken at 72 hours and at 2 months after the acute event in the cardiac arrest and AMI groups, but only once in the control group.

RESULTS

The T3 and free T3 levels at 72 hours in the cardiac arrest group were significantly lower than in both the AMI and control groups (P < 0.0001). On the other hand, there were no significant differences between T4, free T4 and TSH levels between the three groups (P > 0.05). At the 2-month evaluation, a dramatic improvement was observed in T3 and free T3 levels in the cardiac arrest group (P < 0.0001). In those patients whose cardiac arrest duration was in excess of 10 min, levels of T3, free T3, T4 and TSH were significantly lower than those in patients whose cardiac arrest duration was under 5 min (P < 0.001, P < 0.001, P < 0.005 and P < 0.05, respectively).

CONCLUSION

TFTs are significantly altered in cardiac arrest induced by ACS. Changes in TFTs are even more pronounced in patients with longer periods of resuscitation. The changes in the surviving patients were characterized by euthyroid sick syndrome, and this improved by 2 months in those patients who did not progress into a vegetative state.

CPREzy™: an evaluation during simulated cardiac arrest on a hospital bed

CPREzy is a new adjunct designed to improve the application of manual external chest compressions (ECC) during cardiopulmonary resuscitation (CPR). The aim of this study was to determine the effect of using the CPREzy device compared to standard CPR during the simulated resuscitation of a patient on a hospital bed. Twenty medical student volunteers were randomised using a cross over trial design to perform 3 min of continuous ECC using CPREzy and standard CPR. There was a significant improvement in ECC depth with CPREzy compared to standard CPR 42.9 (4.4) mm versus 34.2 (7.6): mm, P = 0.001; 95% CI d.f. 4.4-12.9 mm. This translated to a reduction in the percentage of shallow compressions (<38 mm) with CPREzy 16 (23)% compared to standard CPR 59 (44)%, P = 0.003. There was a small increase in the percentage of compression regarded excessive (>51 mm): CPREzy 6.5 (19)% versus standard CPR 0 (0.1)%. P = 0.012). There was no difference in compression rate or duty cycle between techniques. Equal numbers of participants (40% in each group) performed one of more incorrectly placed chest compression. However the total number of incorrect compressions was higher for the CPREzy group (26% versus 3.9% standard CPR, P < 0.001). This was due to a higher number of low compressions (26% of total compressions for CPREzy versus 1% for standard CPR, P < 0.001). In conclusion, CPREzy was associated with significant improvements in ECC performance. Further animal and clinical studies are required to validate this finding in vivo and to see if it translates to an improvement in outcome in human victims of cardiac arrest.

A comparison between over-the-head and standard cardiopulmonary resuscitation

BACKGROUND

Standard cardiopulmonary resuscitation (CPR) is performed by kneeling adjacent to the side of the casualty. In certain circumstances it may be difficult or impossible to perform CPR in this position, for example in confined spaces such as a narrow corridor, aircraft or train gangway. The aim of this study was to investigate the technique of over-the-head CPR (OTH CPR), where the CPR provider kneels above the casualty and performs chest compressions OTH of the casualty.

METHODS

Twenty volunteers were randomised to a cross over trial where they performed standard and OTH CPR at a 7-day interval. Compression and ventilation variables were recorded on the Laerdal Resusci Annie VAM system.

RESULTS

Chest compression depth and ventilation volume declined over time (0-3 min P < 0.001). There was no difference in compression rate, depth, duty cycle or ventilation rate, inflation rate and ventilation volume between techniques. Hand position was incorrect more frequently in the standard compared to the OTH group (incorrect compressions 300 versus 76, respectively, P < 0.001) due principally to a greater proportion of low positioned compressions in the standard CPR group.

CONCLUSION

OTH CPR appears equally effective as standard CPR with some marginal advantages in correct hand placement. We suggest that in situations where it is not possible to perform standard CPR, OTH CPR may be considered as a suitable alternative.

Do different mattresses affect the quality of cardiopulmonary resuscitation?

OBJECTIVE

To determine the effect of different mattresses on cardiopulmonary resuscitation performance and establish whether emergency deflation of an inflatable mattress improves the quality of resuscitation.

DESIGN AND SETTING

Randomised controlled cross-over trial performed in a general ICU PARTICIPANTS: Critical care staff from a general ICU.

INTERVENTIONS

Cardiopulmonary resuscitation on a manikin on the floor or on a bed with a standard foam mattress and inflated and deflated pressure redistributing mattresses. Maximal compression force was measured at different bed heights.

MEASUREMENTS AND RESULTS

Compression depth, duty cycle and rate and percentage correct expired air ventilation were recorded on a manikin. Compression depth was significantly lower on the foam (35.2 mm), inflated (37.2 mm) and deflated mattress (39.1 mm) than the floor (44.2 mm). There were no clinically important differences in duty cycle or compression rate. The quality of ventilation was poor on all surfaces. Maximal compression force declined as bed height increased.

CONCLUSIONS

Resuscitation performance is adversely affected when performed on a bed (irrespective of mattress type) compared to the floor. There were no differences between the inflated and deflated mattresses, although the deflation process did not adversely affect performance. This study does not support the routine deflation of an inflated mattress during resuscitation and questions the potential benefits from using a backboard. The finding that bed height affects maximal compression forces, challenges the recommendation that cardiopulmonary resuscitation be performed with the bed at middle-thigh level and requires further investigation.

Common faults in resuscitation equipment--guidelines for checking equipment and drugs used in adult cardiopulmonary resuscitation

Successful advanced life support relies, in part, upon the availability and correct functioning of resuscitation equipment. However, numerous publications report deficiencies and defects in key items of resuscitation equipment, particularly those relating to airway management and defibrillation. Some of these are generic and relate to basic device failure (e.g. intrinsic design faults, manufacturing errors, random component failure), external factors (e.g. power failure, gas supply failure, electromagnetic interference) and human error (notably, inadequate knowledge, lack of experience and training, inadequate checking, insufficient maintenance). However, others are device specific. This paper identifies the common, generic faults that lead to equipment malfunction and recommends the resuscitation equipment essential for successful cardiopulmonary resuscitation. It also describes examples of specific equipment malfunction and makes suggestions for the nature and frequency of resuscitation equipment and drug checks, using a structured, and easy-to-recall list.

Mechanism of closed chest cardiopulmonary resuscitation investigated by transoesophageal echocardiography

Transoesophageal echocardiography (TOE) was performed during closed chest cardiopulmonary resuscitation (CPR) in 18 subjects in cardiac arrest. Compression of all four cardiac chambers resulted in forward flow in the pulmonary and systemic circulations, retrograde pulmonary vein flow and incomplete mitral valve closure. Antegrade pulmonary vein flow and left ventricular filling occurred exclusively during the relaxation phase. These findings support the cardiac pump theory of CPR and are incompatible with the thoracic pump mechanism. TOE merits further investigation as a device to monitor and guide resuscitation efforts during CPR.

Adult advanced cardiac life support: the European Resuscitation Council guidelines 1992 (abridged). European Resuscitation Council Working Party

The European Resuscitation Council, established in 1990, is committed to saving lives by improving standards of cardiopulmonary resuscitation across Europe and coordinating the activities of interested organisations and individuals. In this regard the council has successfully brought together physicians and surgeons from eastern and western Europe and, in addition, has established relations with the American Heart Association and equivalent organisations in Canada, Australia, and South Africa. A main objective of the European Resuscitation Council is to produce guidelines for cardiopulmonary and cerebral resuscitation, and in this paper members of a working party of 14 experts from 11 countries set out an abridged version of the council's guidelines for adult advanced cardiac life support. The council hopes that the guidelines and accompanying algorithms will serve as a ready use "how to do it" for ordinary practitioners and paramedics inside and outside hospital.