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Background: Isolated lung transplantation is a viable therapeutic option for many patients with end-stage pulmonary disease. Other intrathoracic surgical procedures have a well documented incidence of phrenic nerve dysfunction, although the incidence after lung transplantation has not been studied., Methods: Thirty-one patients who underwent lung transplantation were evaluated for evidence of phrenic nerve dysfunction and subsequent recovery. Risk factors contributing to the incidence of injury were examined. Phrenic nerve injury was defined by two separate diagnostic tests (Transcutaneous Phrenic Nerve Conduction Studies and Fluoroscopic evaluation of diaphragmatic movement) used in combination., Results: Of the 27 patients who were completely evaluated after the operation, eight had defining criteria for nerve injury--an incidence of 29.6%. Of those affected, the majority of injuries (89%) resulted in complete paralysis of the affected hemidiaphragm. The highest incidence of injury occurred in patients who underwent bilateral single lung transplantation (41%), with the right phrenic nerve being injured most often (78%). Fortunately, no significant postoperative morbidity was attributable to the occurrence of phrenic nerve injury when compared with those patients who did not sustain injury., Conclusions: The analysis of possible risk factors resulted in the hypothesis that the likely mechanism of injury in these patients was due to stretching or direct instrumentation of the nerve, and thus measures should be instituted to minimize the possibility of injury.

beta-Adrenergic agonists are useful for the emergency treatment of asthma. Recently, magnesium sulfate (MgSO4) has also been shown to be efficacious in this situation. beta-Agonists have unwanted cardiovascular and metabolic actions: increased systolic blood pressure, corrected QT interval (QTc), serum glucose and insulin, and decreased RR interval, diastolic blood pressure, serum potassium, phosphate, and calcium. As beta-agonists and MgSO4 quite possibly will be used in combination, we sought to determine how MgSO4 would affect these actions. Healthy young male adults were administered two doses of terbutaline sulfate, 0.25 mg subcutaneously, 30 min apart on two separate occasions, in a randomized, double-blind fashion. On one occasion, 4 g of MgSO4 was administered intravenously over the same 30-min period. On the other, normal saline solution was given as a placebo. Cardiovascular and metabolic variables were measured sequentially for 2 h. Data at 60 min with p values given for a summation of all time points are as follows: MgSO4 increased terbutaline's effects on the RR interval by 0.09 s, p < 0.0001; QTc interval by 0.01 s, p < 0.0007; diastolic blood pressure by 8 mm Hg, p = 0.0001; serum calcium by 0.13 mg/dl, p = 0.01; and glucose by 9 mg/dl, p < 0.0001. MgSO4 also mitigated the systolic blood pressure elevating the effect of terbutaline by 5 mm Hg (p = 0.007). The magnitude of the response potentiations was modest. We conclude that combining terbutaline and MgSO4 is unlikely to result in serious short-term adverse events, if used acutely in patients with relatively normal cardiac and metabolic function. MgSO4 may act by potentiating the effect of beta-agonists on magnesium requiring enzymes such as adenyl cyclase.

Delta9-tetrahydrocannabinol in doses of 0.5, 1.0, 2.0 and 4.0 mg/kg was administered to rats under normal (1 ATA) and increased (3, 5 and 7 times normal) atmospheric pressure. Behavior was maintained by a food-reinforced differential-reinforcemnet-of-low-rate (DRL) schedule. Dose-dependent decrements in performance was observed at the 1 ATA conditions, in which response rates increased and the well-established temporal discrimination disintegrated. Under the elevated pressure conditions, however, a reversal of behavioral toxicity occurred during which performance improved as a function of pressure. The behavioral disruptions occurring at the 5- and 7-ATA pressures were minimal compared with those occurring at 1 ATA under equivalent doses of the drug. The present experiment has demonstrated that delta9-tetrahydrocannabinol produces significant behavioral changes at 1 ATA pressure, but when atmospheric pressure is increased the drug effects are reduced.

Endotracheal suctioning of intubated patients is associated with hemodynamic complications including arterial hypoxemia, cardiac arrhythmias, hypotension and even death. Prior investigations of this subject focus primarily on arterial hypoxemia. Our observations of ETS revealed significant falls in the mixed SvO2 and we postulated that alterations in VO2 or CO must be occurring. This study was then designed to determine the alterations in CO, VO2, SaO2 and the resulting effect on SvO2 during ETS. Ten critically ill intubated patients with pulmonary artery catheters in place, were studied during routine ETS by the nursing staff. We found that ETS produced a significant decrease in SvO2 which was predominantly due to an increased VO2 accompanied by an inadequate rise or even fall in CO. Alterations in SaO2 appeared to be modest and were insensitive indicators of alterations in SvO2.

Morphine sulfate was tested under hyperbaric pressure to assess its effects on behavior. Four male hooded rats were trained to avoid brief electric shocks under a free-operant unsignalled avoidance procedure. Using an individual organism design, we injected each rat subcutaneously with morphine sulfate (2.0, 4.0, 6.0, 8.0 mg/kg body wt.) or saline (0.1 ml/100 g body wt.). Rats were tested at 1.0 and 7.1 atmospheres absolute (ATA) in a dry hyperbaric chamber while breathing a mixture of helium and oxygen. Each session lasted 60 min. Overall, the analgesic effects of morphine at 1.0 and 7.1 ATA were found to be similar. Shock avoidance by a rat was found to be a monotonic function of the drug dose; the fewest shocks were associated with the 2.0 mg/kg dose. Increased pressure did not significantly affect the number of shocks received by a rat across doses. Total responding remained stable throughout the study, but the temporal pattern of responding was differentially influenced by drug dose.