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BACKGROUND: Patients in hemorrhagic shock often require emergent airway management. Clinical experience suggests that oxygen desaturation occurs rapidly in these patients; however, data are scant. The hypothesis of this study was that increasing levels of hemorrhagic shock, varying levels of fraction of inspired oxygen (Fio2) for preoxygenation, and fluid resuscitation significantly affect the duration until critical desaturation occurs. METHODS: Fifteen pigs were studied in a hemorrhagic shock model with controlled hemorrhage (15, 30, and 45 ml/kg blood loss) and randomized to standard fluid resuscitation or no fluids. At each shock level, three apnea experiments (in randomized order) were performed after 5 min of preoxygenation at 21, 50, or 100% Fio2. After preoxygenation, ventilation was discontinued and the time to peripheral oxygen saturation of 70% or less was measured. RESULTS: During normovolemia, peripheral oxygen desaturation to less than 70% occurred after 33+/-7 s (Fio2=0.21, mean+/-SD), 89+/-12 s (Fio2=0.5), and 165+/-22 s (Fio2=1.0; P<0.001). During increasing blood loss, peripheral oxygen desaturation to Spo2 less than 70% occurred significantly (P<0.001) faster compared with normovolemia, but no effect of fluid resuscitation was observed. With 45 ml/kg blood loss, peripheral oxygen desaturation to less than 70% occurred after approximately 15 (Fio2=0.21) to 65 (Fio2=0.5) to 140 s (Fio2=1.0). CONCLUSIONS: Findings from this swine hemorrhagic shock model confirm that Fio2 and the level of hemorrhagic shock, but not fluid resuscitation, influence the rate of apneic desaturation. A five-fold increase in time until critical oxygen desaturation occurs can be achieved when preoxygenating with 100% oxygen compared with room air, underscoring the importance of adequate preoxygenation before emergent airway management. [ABSTRACT FROM AUTHOR]

Simulation of cardiac cryoablation by the finite element method can contribute to optimizing ablation results and understanding the effects of modifications prior to time-consuming and expensive experiments. In this work an intervention scenario using a 9 Fr 8 mm tip applicator applied to ventricular tissue was simulated using the effective heat capacity model based on Pennes' bioheat equation. Using experimentally obtained refrigerant flow rates and temperature profiles recorded by a thermocouple located at the tip of the applicator the cooling performance of the refrigerant was estimated and integrated by time and temperature dependent boundary conditions based on distinct phases of a freeze-thaw cycle. Our simulations exhibited a mean difference of approximately 6°C at the applicator tip compared to temperature profiles obtained during in vivo experiments. The presented model is a useful tool for simulation and validation of new developments in clinical cardiac cryoablation., (Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.)

Aim: Stomach inflation during cardiopulmonary resuscitation (CPR) is frequent, but the effect on haemodynamic and pulmonary function is unclear. The purpose of this study was to evaluate the effect of clinically realistic stomach inflation on haemodynamic and pulmonary function during CPR in a porcine model., Methods: After baseline measurements ventricular fibrillation was induced in 21 pigs, and the stomach was inflated with 0L (n=7), 5L (n=7) or 10L air (n=7) before initiating CPR., Results: During CPR, 0, 5, and 10L stomach inflation resulted in higher mean pulmonary artery pressure [median (min-max)] [35 (28-40), 47 (25-50), and 51 (49-75) mmHg; P<0.05], but comparable coronary perfusion pressure [10 (2-20), 8 (4-35) and 5 (2-13) mmHg; P=0.54]. Increasing (0, 5, and 10L) stomach inflation decreased static pulmonary compliance [52 (38-98), 19 (8-32), and 12 (7-15) mL/cmH(2)O; P<0.05], and increased peak airway pressure [33 (27-36), 53 (45-104), and 103 (96-110) cmH(2)O; P<0.05). Arterial oxygen partial pressure was higher with 0L when compared with 5 and 10L stomach inflation [378 (88-440), 58 (47-113), and 54 (43-126) mmHg; P<0.05). Arterial carbon dioxide partial pressure was lower with 0L when compared with 5 and 10L stomach inflation [30 (24-36), 41(34-51), and 56 (45-68) mmHg; P<0.05]. Return of spontaneous circulation was comparable between groups (5/7 in 0L, 4/7 in 5L, and 3/7 in 10L stomach inflation; P=0.56)., Conclusions: Increasing levels of stomach inflation had adverse effects on haemodynamic and pulmonary function, indicating an acute abdominal compartment syndrome in this CPR model.