Evaluation of LUCAS, a new device for automatic mechanical compression and active decompression resuscitation

Abstract

LUCAS is a new gas-driven CPR device providing automatic chest compression and active decompression. In an artificial thorax model, superior pressure and flow were obtained with LUCAS compared with manual CPR. In a randomized study on pigs with induced ventricular fibrillation significantly higher cardiac output, carotid artery blood flow, end-tidal CO₂, intrathoracic decompression-phase aortic- and coronary perfusion pressures were obtained with LUCAS-CPR (83% ROSC) compared to manual CPR (0% ROSC). In normothermic fibrillating pigs, the ROSC rate was 100% after 15 min and 38% after 60 min of LUCAS-CPR (no drug treatment). The ROSC rate increased to 75% if surface cooling to 34 °C was applied during the first 30 min of the 1-h resuscitation period. Experience with the first 20 patients has shown that LUCAS is light (6.5 kg), easy to handle, quick to apply (10–20 s), maintains a correct position, and works optimally during transport both on stretchers and in ambulances. In one hospital patient with a witnessed asystole where manual CPR failed, LUCAS-CPR achieved ROSC within 3 min. One year later the patient's mental capacity was fully intact. To conclude, LUCAS-CPR gives significantly better circulation during ventricular fibrillation than manual CPR.

Sumàrio

LUCAS é um novo aparelho de RCP que funciona com gás e que faz compressão torácica automática e descompressão activa. Num estudo randomizado em porcos com fibrilhação ventricular induzida foram estudados o débito cardı́aco, fluxo sanguı́neo da artéria carótida, CO₂ no final da expiração e pressões de perfusão coronária e aórtica na fase de descompressão intratorácica , que se verificou serem significativamente mais elevadas com a RCP com LUCAS (83% ROSC) quando comparado com RCP Manual (0% ROSC). Em porcos normotérmicos em fibrilação a taxa de ROSC foi 100% ao fim de 15 min e 38% ao fim de 60 min de RCP-LUCAS (sem tratamento farmacológico). A taxa de ROSC aumentou para 75% se fosse aplicado arrefecimento superficial até aos 34 °C nos primeiros 30 min da primeira hora do perı́odo de reanimação. A experiência com os primeiros 20 doentes mostrou que o LUCAS é leve (6.5Kg), fácil de manejar, rápido de aplicar (10–20 s), mantém uma posição correcta e trabalha de forma óptima durante o transporte em macas ou em ambulâncias. Num doente hospitalar com uma assistolia testemunhada em que a RCP manual falhou a RCP-LUCAS conseguiu ROSC em 3 min. Um ano mais tarde a capacidade intelectual do doente estava intacta. Para concluir, a RCP-LUCAS dá uma circulação significativamente melhor que a RCP manual durante a fibrilação ventricular.

Resumen

LUCAS es un nuevo aparato para reanimación cardiopulmonar impulsado por gas que proporciona compresiones torácicas y descompresiones activas automáticas. En un modelo de tórax artificial, se obtuvo presión y flujo superiores con LUCAS comparado con reanimación cardiopulmonar manual. En un estudio randomizado en cerdos con fibrilación ventricular inducida se alcanzaron valores significativamente mayores de gasto cardı́aco, flujo de arteria coronaria, CO₂ espiratorio, presiones de perfusión coronaria y aórtica en fase de descompresión con reanimación con LUCAS (83% ROSC) comparado con reanimación manual (0% ROSC). En cerdos normotérmicos en fibrilación ventricular, la tasa de retorno a circulación espontánea (ROSC) fue de 100% después de 15 minutos y de 38% después de 60 minutos de LUCAS-RCP (sin tratamiento con drogas).La tasa de ROSC a 75% si se aplicaba enfriamiento superficial a 34 °C en los primeros 30 minutos de el perı́odo de una hora de resucitación. La experiencia con los primeros 20 pacientes ha mostrado que LUCAS es liviano (6.5 kg), fácil de usar, rápido para aplicar (10–20s), mantiene la posición correcta, y trabaja óptimamente durante el transporte, tanto en camillas como en ambulancias. En un paciente de hospital con un paro presenciado en asistolı́a, sonde la RCP manual falló, RCP-LUCAS consiguió ROSC en tres minutos. Un año más tarde la capacidad mental del paciente estaba intacta. Para concluir, durante la fibrilación ventricular la RCP-LUCAS proporciona una circulación significativamente mejor que la RCP manual.

Introduction

Cardiac arrest, either as asystole or as ventricular fibrillation (VF), is the most dramatic situation in medicine. Since Kouwenhoven and coworkers published their landmark article in 1960 [1], manual closed-chest compressions (combined with mouth-to-mouth ventilation) has been established as the initial treatment of choice for circulatory arrest, followed by defibrillation as soon as the equipment is available, if VF is the cause of the collapse. With proper training, anyone, anywhere can initiate cardio-pulmonary resuscitation (CPR). However, due to fatigue, manual CPR cannot be given for more than a few minutes before it becomes ineffective [2], and it cannot be given effectively at all during transport [3]. Most cardiac arrests occur out-of-hospital and the survival rates are very poor; in most published reports the 1-year survival rate is less than 5%. In a randomized study, Plaisance and coworkers [4] compared standard manual CPR (n=377 patients) with active compression/decompression CPR performed manually with the CardioPump (AMBU, Copenhagen, Denmark) (n=373 patients). The 1-year survival rate was very poor in both groups, 2 versus 5% (P=0.03); all resuscitation efforts with either method were performed only at the scene of the cardiac arrest, and only if they were successfully resuscitated at the scene were the patients transported to hospital. To prevent fatigue, the rescuers were instructed to alternate after each 3 min of CPR. The study of Plaisance et al. demonstrates the need for a mechanical device giving adequate compressions/decompressions continuously until the patient can be delivered to a hospital with all facilities for the treatment of heart disease, including direct PTCA and heart surgery.

Most devices for mechanical chest compression in use today have operational limitations because they take too long to apply, they are cumbersome to install and operate, they are unstable on the chest, heavy, and expensive to purchase [5]. Therefore, no mechanical device for chest compression/decompression currently is used routinely in clinical practice, in spite of the obvious limitations of manual CPR. Recently, a new device named LUCAS, has been made commercially available (Fig. 1, Fig. 2). It is designed to give automatic mechanical chest compression and active decompression. It is portable and works during transport both on stretchers and in ambulances.

The aim of the present investigation was to compare the efficacy of LUCAS with that of manual compressions on an artificial thorax model allowing exact analysis of pressure- and flow-curves, and on a pig model in which relevant physiological variables could be registered. In an earlier study using the same pig model we studied the effects of adrenaline (epinephrine) and noradrenaline (norepinephrine) on end-tidal CO₂, coronary perfusion pressure and cardiac output during cardiopulmonary resuscitation [6]. In the present study we decided to eliminate all drug therapy in order to elucidate the effects of chest compressions per se. Data from the first clinical pilot study with LUCAS are also presented.