Normothermia is protective during infrarenal aortic surgery.

PURPOSE: Mild hypothermia has been suggested to be protective against tissue ischemia during aortic operations. However, recent studies have documented detrimental cardiac effects of hypothermia during a variety of operative procedures. The influence of different warming methods and the impact of hypothermia during standard aortic procedures was assessed. METHODS: One hundred patients who underwent repair of infrarenal aortic aneurysms or aortoiliac occlusive disease were prospectively randomized into 2 groups, receiving either a circulating water mattress or a forced air warming blanket. Adjuvant warming methods were standardized. The day before surgery, 48-hour Holter monitors were applied and interpreted by a cardiologist blinded to the treatment. Randomization resulted in equivalent groups with regard to patient history, indications for surgery, body mass index, length of surgery, and fluid requirements. RESULTS: Core temperatures were significantly warmer during surgery (36.3 degrees C +/- 0.7 degrees C vs 35.4 +/- 0.8 degrees C) and after surgery (36.4 degrees C +/- 0.7 degrees C vs 35.6 degrees C +/- 0.9 degrees C) in patients with forced air warming (P <.001). The circulating water mattress group had significantly more metabolic acidosis perioperatively (P =.03). Postoperative length of stay, cardiac complications, and death rates were not significantly different. Subgroup analysis of 83 aneurysm patients comparing normothermia with hypothermia (temperature less than 36 degrees C) on arrival to the recovery room identified decreased cardiac output (P =.02), thrombocytopenia (P =.02), elevated prothrombin time (P =.04), and inferior Acute Physiology and Chronic Health Evaluation (APACHE) II scores (P <.001) in the hypothermic group. Holter analysis revealed more sinus tachycardia (ST) segment changes and ventricular tachycardia in hypothermic aneurysm patients (P =.05). CONCLUSION: Patients treated with forced air blankets had significantly less metabolic acidosis and were kept significantly warmer than those treated with circulating water mattresses. Patients with aneurysms that were kept normothermic had a significantly improved clinical profile, with fewer cardiac events on the Holter recordings. We therefore conclude that (1) normothermia is protective for infrarenal aortic surgical patients; and (2) forced air warming blankets provide improved temperature maintenance compared with circulating water mattresses.

A functional approach to the preexcitation syndromes.

Electrophysiologic studies have been used to elicit the mechanisms of the preexcitation syndromes and have become a therapeutic tool over the past decade. A thorough understanding of the physiology and anatomy of accessory pathways that are responsible for preexcitation and the associated arrhythmias is necessary before considering the various forms of intervention. The approach to patients with preexcitation syndromes is discussed, with an emphasis on the functional properties of accessory pathways and the associated arrhythmias.

Myosin light chain phosphorylation in 32P-labeled rabbit aorta stimulated by phorbol 12,13-dibutyrate and phenylephrine.

The mechanism(s) of force development in vascular smooth muscle following pharmacological activation of protein kinase C by phorbol esters are not known. In this study, we examined the myosin light chain phosphorylation response following stimulation by phorbol 12,13-dibutyrate (PDB) or phenylephrine in rabbit aorta which had been incubated with 32PO4 in order to label ATP pools. Through tryptic phosphopeptide mapping of myosin light chain from intact tissue and comparison to controls using purified components, we inferred that Ca2+-dependent force stimulated by PDB was associated with small increases in serine-19 phosphorylation, consistent with a contractile mechanism involving indirect activation of myosin light chain kinase. Additional residues, consistent with the in vitro substrate specificity of protein kinase C, were also observed to be phosphorylated in response to PDB and represented proportionately a larger fraction of the total phosphorylated myosin light chain in Ca2+-depleted tissues. Stimulation by an alpha 1-adrenergic agonist (phenylephrine) resulted in phosphorylation of residues which were consistent with an activation mechanism involving myosin light chain kinase only. These results indicate that in rabbit aorta the contractile effects of PDB may be partially mediated by Ca2+-dependent activation of myosin light chain kinase. However, the data do not rule out a component of the PDB-stimulated contractile response which is independent of myosin light chain phosphorylation on the serine-19 residue. In addition, activation by a more physiological stimulus, phenylephrine, does not result in protein kinase C-mediated myosin light chain phosphorylation.

Chylous ascites after abdominal aortic aneurysmectomy: successful management with a peritoneovenous shunt.

Postoperative chylous ascites is a rare complication of aortic aneurysmectomy. Although increasing numbers of abdominal aortic aneurysms are being resected annually, there have been only eight previously reported cases of chylous ascites after this operation. This article describes the ninth case of postoperative chylous ascites after abdominal aortic aneurysm resection and emphasizes the value of management with peritoneovenous shunting.

The preoperative liver scan and surgical decision-making in patients with colorectal cancer.

The influence of preoperative liver scans and liver function tests on surgical decision-making was analyzed in 196 patients who underwent surgical therapy for colorectal cancer. One hundred and thirteen patients who had preoperative liver scans were compared with 83 patients who did not. No statistically significant difference existed between the liver scan group and the nonscan group in terms of when surgical decision-making occurred. Likewise, the results of the liver scan did not influence when operative decisions were made. The majority of decision-making occurred intraoperatively when ultimate confirmation of the presence or absence of hepatic metastases was made. Presumptive surgical decisions were made preoperatively, but final decisions occurred intraoperatively when all relevant patient data could be correlated. Liver scanning has limited usefulness in the preoperative evaluation of patients with colon cancer as it does not affect decision-making and is much more costly than liver function testing.