An impedance threshold device did not improve carotid blood flow in a porcine model of prolonged cardiac arrest.

BACKGROUND: An impedance threshold device (ITD) was developed to increase venous return to the heart and therefore increase cardiac output and organ blood flow during cardiopulmonary rescue (CPR). Basic CPR aims to maintain coronary and cerebral blood flow at the minimum level necessary for survival. The present study compared the effects of an ITD on cerebral blood flow assessed as blood flow in both carotid arteries to the blood flow of a control group during prolonged CPR. METHODS: Fourteen anaesthetized pigs were monitored during 60 min of CPR after induced ventricular fibrillation. The primary outcome was blood flow in both carotid arteries, and the secondary outcomes were blood pressure, acid-base parameters, plasma potassium, and plasma lactate. The pigs were randomized to mechanical compressions and ventilation with an ITD added to the ventilation or to a control group treated only with mechanical compressions and ventilation. The time course for the parameters was tested using analysis of variance. RESULTS: The cumulative carotid blood flow in the ITD group decreased from 64 to 42 ml/min, and it decreased from 69 to 51 ml/min in the control group during 60 min of CPR. The difference was not significant. The secondary outcome measures were also not significantly different. CONCLUSIONS: This study did not show any beneficial effect of an ITD on carotid blood flow.

Long-Distance Transportation of Carbon Monoxide-Poisoned Patients on Extracorporeal Membrane Oxygenation Seems Possible: A Porcine Feasibility Study.

OBJECTIVE: Extracorporeal membrane oxygenation (ECMO) has been widely used to stabilize patients with impairment of cardiac/respiratory function, and ECMO has been used to stabilize cardiopulmonary insufficiency caused by carbon monoxide (CO) poisoning in a porcine model. Airborne transportation in fixed wing aircraft of patients suffering from CO poisoning is challenging because as the air pressure drops, the oxygen content falls correspondingly. The aim of this study was to show the feasibility of cannulating and establishing ECMO therapy during airborne transportation after severe CO poisoning in a porcine model. METHODS: An anesthetized pig was subjected to severe CO poisoning and loaded onto a Hercules aircraft. Cardiac arrest was induced at an altitude of 8,000 feet, after which cannulation and the establishment of venoarterial (VA) ECMO were performed. Vital signs were monitored, and arterial blood samples were analyzed while airborne. RESULTS: CO poisoning was induced with carboxyhemoglobin at 58% before takeoff. We successfully cannulated the animal in-flight during cardiac arrest and initiated VA ECMO. The animal regained spontaneous circulation and was successfully weaned from ECMO. During VA ECMO, PaO2 was maintained at high levels (420-615 mm Hg). CONCLUSION: It is possible to cannulate and initiate VA ECMO treatment as airborne en route therapy for cardiac arrest and severe CO intoxication in a porcine model.

ECMO improves survival following cardiogenic shock due to carbon monoxide poisoning - an experimental porcine model.

BACKGROUND: Severe intoxication with carbon monoxide (CO) is extremely lethal and causes numerous deaths due to cardiac or respiratory failure. Conventional intensive treatment may not be sufficient. The aim of this study was to investigate the treatment effect of extracorporeal veno-arterial extracorporeal membrane oxygenation (ECMO) following severe CO poisoning in an experimental porcine model. METHODS: A total of twelve pigs were anaesthetized, routinely monitored and intoxicated by inhalation of CO until the beginning of cardiac failure and randomized to a treatment (ventilator using an FiO2 of 100% or ECMO). In the case of cardiac arrest, advanced resuscitation using standard guidelines was performed for at least 10 min. ECMO was also initiated in the ventilation group if the return of spontaneous circulation did not occur within 10 min. Lung tissue biopsies were obtained before and after CO intoxication. RESULTS: All animals in the ECMO group survived; however, one had to be resuscitated due to cardiac arrest. A single animal survived in the ventilator group, but five animals suffered from cardiac arrest at an average of 11.8 min after initiation of treatment. Conventional resuscitation failed in these animals, but four animals were successfully resuscitated after the establishment of ECMO. A significant decrease was noticed in PO2 with increasing HbCO, but there was no increase in pulmonary vascular resistance. No differences in H&E-stained lung tissue biopsies were observed. CONCLUSIONS: The use of ECMO following severe CO poisoning greatly improved survival compared with conventional resuscitation in an experimental porcine model. This study forms the basis for further research among patients.