Inhibition of inducible nitric oxide synthase after myocardial ischemia increases coronary flow.

BACKGROUND: The role of nitric oxide synthase in myocardial ischemia-reperfusion injury is complex. Our hypothesis was that inducible nitric oxide synthase has a role in the regulation of coronary flow after ischemia. METHODS: Four groups of isolated blood-perfused rabbit hearts underwent sequential periods of perfusion, ischemia, and reperfusion (20, 30, and 20 minutes). Two groups underwent 40 minutes of perfusion. Ischemic groups received saline vehicle, N omega-nitro-L-arginine methyl ester (L-NAME) or the highly specific inducible nitric oxide synthase inhibitor 1400W in low or high doses during reperfusion. Two nonischemic groups were treated with saline vehicle or 1400W during the last 20 minutes of perfusion. Left ventricular developed pressure and coronary flow were measured after each perfusion period. Ventricular levels of myeloperoxidase and cyclic guanosine monophosphate were measured at the end of the second perfusion period. RESULTS: Coronary flow was significantly increased in both 1400W groups versus L-NAME (p < 0.001) and in high-dose 1400W versus control (p < 0.001). Coronary flow was not significantly different between the nonischemic groups. Left ventricular developed pressure was not significantly different among the ischemic groups or between the two nonischemic groups. There were no differences in cyclic guanosine monophosphate levels in any of the ischemic hearts. Myeloperoxidase levels were significantly elevated in L-NAME versus high-dose 1400W, nonischemic 1400W, and nonischemic saline groups (p < 0.02). CONCLUSIONS: Highly selective inhibition of inducible nitric oxide synthase results in increased coronary flow after ischemia but not after continuous perfusion. This occurs with decreased neutrophil accumulation and a trend toward increased contractility without elevation of cyclic guanosine monophosphate levels.

The utility of preoperative laboratory testing in general surgery patients for outpatient procedures.

The utility of obtaining routine preoperative laboratory (lab) screening tests was evaluated for a 1-year period in general surgery clinic patients undergoing ambulatory surgical procedures at a teaching hospital. This study sought to determine whether those lab tests not indicated by patient history or physical examination would identify abnormalities that might influence perioperative care of the ambulatory surgical patient or predict perioperative complications. The charts of 142 patients undergoing 155 procedures were reviewed. A total of 300 tests were ordered, with 92 (30.6%) being abnormal. Of the 125 tests indicated, 54 (43.2%) were abnormal, whereas in those lab tests not indicated, 38 (21.7%) were found to be abnormal. In four instances, an abnormal lab test (4 out of 300) result was clinically significant (1.3%), causing cancellation of the surgical procedure in two cases (both indicated lab tests) and diagnosis of urinary tract infection in two patients (both routine urinalyses). Forty-eight of the 142 patients had no preoperative lab tests ordered (34%), with no perioperative complications resulting. Patient charges totaled $15,725 for all lab tests ordered, with $8,573 in charges attributed to those tests not indicated. If lab tests for all general and subspecialty surgical outpatients had been ordered as dictated by patient medical history and physical examination rather than by either routine or by arbitrary criteria, our medical facility could have potentially reduced patient charges by more than $400,000 in the year reviewed, assuming a 52.4 per cent savings as noted above, with no expected adverse outcomes.