A model of hemorrhagic shock and acute lung injury in Landrace-Large White Swine.

Traumatic injury is a leading cause of death worldwide for people between 5 and 44 y of age, and it accounts for 10% of all deaths. The incidence of acute lung injury, a life-threatening complication in severely injured trauma patients remains between 30% and 50%. This study describes an experimental protocol of volume-controlled hemorrhage in Landrace-Large White swine. The experimental approach simulated the clinical situation associated with hemorrhagic shock in the trauma patient while providing controlled conditions to maximize reproducibility. The duration of the protocol was 8 h and was divided into 5 distinct phases-stabilization, hemorrhage, maintenance, resuscitation, and observation-after which the swine were euthanized. Lung tissue samples were analyzed histologically. All swine survived the protocol. The hemodynamic responses accurately reflected those seen in humans, and the development of acute lung injury was consistent among all swine. This experimental protocol of hemorrhagic shock and fluid resuscitation in Landrace-Large White swine may be useful for future study of hemorrhagic shock and acute lung injury.

Use of the impedance threshold device in cardiopulmonary resuscitation.

Although approximately one million sudden cardiac deaths occur yearly in the US and Europe, cardiac arrest (CA) remains a clinical condition still characterized by a poor prognosis. In an effort to improve the cardiopulmonary resuscitation (CPR) technique, the 2005 American Heart Association (AHA) Guidelines for CPR gave the impedance threshold device (ITD) a Class IIa recommendation. The AHA recommendation means that there is strong evidence to demonstrate that ITD enhances circulation, improves hemodynamics and increases the likelihood of resuscitation in patients in CA. During standard CPR, venous blood return to the heart relies on the natural elastic recoil of the chest which creates a transient decrease in intrathoracic pressure. The ITD further decreases intrathoracic pressure by preventing respiratory gases from entering the lungs during the decompression phase of CPR. Thus, although ITD is placed into the respiratory circuit it works as a circulatory enhancer device that provides its therapeutic benefit with each chest decompression. The ease of use of this device, its ability to be incorporated into a mask and other airway devices, the absence of device-related adverse effects and few requirements in additional training, suggest that ITD may be a favorable new device for improving CPR efficiency. Since the literature is short of studies with clinically meaningful outcomes such as neurological outcome and long term survival, further evidence is still needed.

Refined induction of anesthesia with remifentanil after bolus propofol administration in Landrace/Large White swine.

The authors report a prospective randomized blind study in which they used a refined anesthetic technique in male Landrace/Large White swine (n = 125 pigs, 19 ± 2 kg, 10-15 weeks old). The animals were first premedicated with ketamine, midazolam and atropine and then given a dose of 1, 2, 3, 4 or 5 µg remifentanil per kg body weight (dose amounts were randomly assigned) after a bolus dose of propofol. The authors assessed the intubation conditions (e.g., jaw relaxation and other parameters) 20 min after premedication and then 5 min after anesthesia induction. All animals that received each of the different remifentanil dose amounts were successfully intubated in less than 30 s. No animal developed apnea during intubation or experienced substantial reductions in heart rate or blood pressure (> 25%) between the two time points (20 min after premedication and 5 min after anesthesia induction). Overall intubation conditions were significantly better in animals that received 5 µg remifentanil per kg body weight than in animals that received other dose amounts (P < 0.001). The average time to intubation was significantly shorter for animals that received 5 µg remifentanil per kg body weight than for animals that received any of the other dose amounts (P < 0.001). The authors concluded that for this study, 5 µg remifentanil per kg body weight resulted in excellent intubating conditions in this swine breed.