Fiberoptic light source-induced surgical fires -- the contribution of forced-air warming blankets.

BACKGROUND: Fiberoptic light sources have been identified as a fire ignition mechanism in the operating room. This study attempted to determine whether a forced-air warming blanket (FAWB) could affect the ignition or spread of fire caused by a fiberoptic light source. METHODS: We exposed surgical drapes to a fiberoptic light source at close range. The results were categorized according to time to first smoke and damage resulting at 1 min. Data were analyzed using the Mann-Whitney rank-sum test. RESULTS: The sums of the rank values for the components of the drape indicated that there was a greater than 96.8-99.2% chance that the FAWB accelerated the time to first smoke. The FAWB appeared to protect the patient gown from damage during all trials. The presence of an FAWB under a surgical drape accelerated the time to first smoke when exposed to unprotected fiberoptic light sources, yet prevented damage to the underlying patient gown. In an actual surgical setting, it is likely that the FAWB would offer some protection to the patient's skin directly below the surgical drape. CONCLUSION: It is likely that the FAWB can offer some protection to the patient should an unprotected fiberoptic light source cause a fire.

Effect of nitric oxide synthase inhibition on cardiorespiratory responses in the conscious rat.

Nitric oxide synthase (NOS) blockade was used to test the cardioventilatory responses to hypercapnia and hypoxia in freely behaving animals. Chronically instrumented adult Sprague-Dawley rats were studied before and after intravenous administration of either 100 mg/kg of NG-nitro-L-arginine methyl ester (L-NAME), a nonspecific NOS blocker, or 10 mg/kg of S-methyl-L-thiocitrulline (SMTC), a selective neural NOS inhibitor. L-NAME injection induced sustained blood pressure (BP) elevation with transient tachycardia and increased minute ventilation (VE), which returned to baseline within minutes. SMTC elicited similar, although transient, BP increases; however, heart rate and VE decreased. L-NAME and SMTC did not modify overall steady-state hypercapnic responses. In control conditions, hypoxia induced early VE increases with further VE enhancements at 30 min. L-NAME increased the early VE response to 10% O2 but induced late VE reductions in hypoxia. SMTC did not change early VE responses but induced marked reductions in the later VE hypoxic responses. In control animals, hypoxia induced a significant heart rate increase. This increase was absent during the early response after SMTC and was followed in both L-NAME- and SMTC-treated animals by significant heart rate reductions to values below room air. Similarly, the sustained BP response to hypoxia in control animals was absent after administration of NOS inhibitors. These findings suggest that NOS activity exerts excitatory influences on respiration and cardiac chronotropy and sustained vasomotor tone during hypoxia. We speculate that NOS-mediated mechanisms may play an important role in hypoxia-induced ventilatory roll-off during wakefulness.

Spontaneous regression of a choroidal hemangioma following pregnancy.

A 30-year old white woman was seen with a 2 month history of decreased vision in the right eye. She was 5 months pregnant at this time. Examination showed a large, slightly elevated choroidal hemangioma along the superior temporal arcade. Overlying subretinal fluid involved the superior part of the macula. After the delivery of the child, the tumor regressed. This exacerbation and regression of a choroidal hemangioma during pregnancy and delivery were documented with fundus photography and fluorescein angiography.