The critical importance of minimal delay between chest compressions and subsequent defibrillation: a haemodynamic explanation
ABSTRACT Outcome after prehospital defibrillation remains dire. The aim of the present study was to elucidate the pathophysiology of cardiac arrest and to suggest ways to improve outcome. Ventricular fibrillation (VF) was induced in air-ventilated pigs, after which ventilation was withdrawn. After 6.5 min of VF, ventilation with 100% oxygen was initiated. In six pigs (group I), defibrillation was the only treatment carried out. In another six pigs (group II), mechanical chest compression-decompression CPR (mCPR) was carried out for 3.5 min followed by a 40-s hands-off period before defibrillation. If unsuccessful, mCPR was resumed for a further 30 s before a second or a third, 40-s delayed, shock was given. In a final six pigs (group III) mCPR was applied for 3.5 min after which up to three shocks (if needed) were given during on-going mCPR. Return of spontaneous circulation (ROSC) occurred in none of the pigs in group I (0%), in 1 of six pigs in group II (17%) and in five of six pigs in group III (83%). During the first 3 min of VF arterial blood was transported to the venous circulation, with the consequence that the left ventricle emptied and the right ventricle became greatly distended. It took 2 min of mCPR to establish an adequate coronary perfusion pressure, which was lost when the mCPR was interrupted. During 30 s of mCPR coronary perfusion pressure was negative, but a carotid flow of about 25% of basal value was obtained. In this pig model, VF caused venous congestion, an empty left heart, and a greatly distended right heart within 3 min. Adequate heart massage before and during defibrillation greatly improved the likelihood of return of spontaneous circulation (ROSC).
- SourceAvailable from: Trygve Sjöberg
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- "With a 6.5 l gas bottle (300 kPa) LUCAS can be run for about 30 min. A detailed description of the device and how it may be used have been given elsewhere   . "
ABSTRACT: Lund University Cardiopulmonary Assist System (LUCAS) is a new gas-driven CPR device providing automatic chest compression and active decompression. This is a report of the first 100 consecutive cases treated with LUCAS due to out-of-hospital cardiac arrest (58% asystole, 42% ventricular fibrillation (VF)). Safety aspects were also investigated and it was found that LUCAS can be used safely regarding noise levels and oxygen concentrations within the ambulance. A crash test (10G) showed no displacement of the device from the manikin. Of the 71 patients with witnessed cardiac arrest, 39% received bystander CPR. In those 28 patients where LUCAS-CPR was initiated more than 15 min after the ambulance alarm and in the 29 unwitnessed cases, none survived for 30 days. Of the 43 witnessed cases treated with LUCAS within 15 min, 24 had VF and 15 (63%) of these cases achieved a stable return of spontaneous circulation (ROSC) and 6 (25%) of them survived with a good neurological recovery after 30 days; 5 (26%) of the 19 patients with asystole achieved ROSC and 1 (5%) survived for over 30 days. One patient where ROSC could not be achieved was transported with on-going LUCAS-CPR to the catheter laboratory and after PCI for an occluded LAD a stable ROSC occurred, but the patient never regained consciousness and died 15 days later. To conclude, establishment of an adequate cerebral circulation as quickly as possible after cardiac arrest is mandatory for a good outcome. In this report patients with a witnessed cardiac arrest receiving LUCAS-CPR within 15 min from the ambulance call had a 30-day survival of 25% in VF and 5% in asystole, but if the interval was more than 15 min, there were no 30-day survivors.Resuscitation 11/2005; 67(1):25-30. DOI:10.1016/j.resuscitation.2005.05.013 · 3.96 Impact Factor
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- "The efficacy of chest compressions during CPR is of the utmost importance for survival . Even the results of defibrillation attempts will be improved by correct chest compressions prior to DC shock, if the cardiac arrest lasts longer than a few minutes  . Suboptimal performance as well as complications, which might interfere with outcome, should be avoided by appropriate training. "
ABSTRACT: The technique of chest compression recommended in the recent international guidelines is different from that which was traditionally used in Hungary. While compression force, location, frequency and duty cycle are all identical, the position of the hand on the chest is different. The aim of our study was to compare these two methods concerning the area and location of the surface compressed on the chest wall. Thirty-eight doctors were trained in both compression methods. Compressions were carried out on an AMBU Man-C manikin. The compressed surface, marked by using a carbon paper, was projected on to a standardised 10 mm x 10 mm matrix to measure the area and location. The chest surface was marked subsequently as green, yellow and red areas to identify the correct position, incorrect position and dangerous areas. All subjects did chest compressions using both techniques (I, International; H, traditional Hungarian) in a random order each for 30 s. The surface area compressed was significantly larger by the H method than the I method (73.46 (+/-17.11) versus 41.75 (+/-11.08), p<0.005). 8.07 (+/-1.91) cm2 of an area considered dangerous were compressed by the H method compared to 2.93 (+/-0.78) cm2 by the I method (p<0.005). Comparing the two different methods of chest compressions, the hand position recommended by the recent international guidelines seems to be more safe as it compresses a smaller area which might cause injury.Resuscitation 09/2005; 66(3):297-301. DOI:10.1016/j.resuscitation.2005.03.010 · 3.96 Impact Factor