Edward A. Stemmer

Complications of indwelling venous catheters: With particular reference to catheter embolus

Abstract The complications with the use of polyethylene catheters are discussed and the world literature is reviewed. The twenty-six previously reported cases of polyethylene catheter embolus are analyzed. Ten cases of embolus from our teaching hospitals are reviewed and an additional thirteen cases from the Los Angeles area are added. The mortality from catheter embolus is high unless vigorous surgical measures are instituted for removal. The factors leading to catheter breakage and the measures to be taken for prevention are discussed. Treatment for catheter embolus is outlined.

Noninvasive Cardiac Output: Simultaneous Comparison of Two Different Methods with Thermodilution

The authors attempted to simultaneously measure cardiac output by thermodilution (COtd), thoracic bioimpedance (CObi), and suprasternal Doppler ultrasound (COdopp) in 68 patients. Subgroups separately compared included patients whose lungs were mechanically ventilated, patients undergoing cardiac surgery, aortic surgery, patients with dysrhythmias, and patients with sepsis. The authors also studied the value of the ventricular ejection time (VET) in evaluating the agreement of CObi and COdopp with COtd. Simultaneous CObi and COtd were available in a total of 56 patients (416 data sets) with an overall correlation coefficient r = 0.61, regression slope (m) of 0.52, intercept (y) of 2.46, and mean (CObi-COtd) difference (bias) of -0.67 +/- 1.72 (SD) l/min. Simultaneous COdopp and COtd were available in 59 patients (446 data sets) with an overall r = 0.51, m of 0.53, y of 2.05, and bias of -0.79 +/- 1.95 l/min. CObi agreed most closely with COtd in patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and with VET difference less than 40 ms (16 patients, 99 data sets; r = 0.74; m = 0.97; y = 0.15; bias = -0.02 +/- 1.53 l/min). COdopp agreed most closely with COtd in patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and in sinus rhythm with VET difference less than 40 ms (10 patients, 45 data sets; r = 0.82; m = 0.98; y = -0.07; bias = -0.82 +/-1.03 l/min). VET by radial artery can help evaluate the reliability of CObi and COdopp.

Improved results with carotid endarterectomy.

Two hundred ninety patients undergoing carotid endarterectomy were reviewed. From 1968 to 1972, 188 patients had carotid endarterectomy under general anesthesia with use of a shunt and hypercarbia. Stump pressures were not recorded in this group. There were three deaths, three postoperative hemiplegias and two complications of transient limb weakness. From 1973 to 1975, 102 patients were operated on under local anesthesia with systemic Innovar and Sublimaze, normocarbia and intra-operative assessment of stump pressure. In this group there was one death, no hemiplegia, and no complications of transient limb weakness. Twenty of the 102 were shunted either on the basis of stump pressure or the loss of motor ability or consciousness on carotid clamping. Those shunted had stump pressures ranging from 10 to 70 mm Hg with a mean of 20 while those not shunted had stump pressures ranging from 20 to 85 mm Hg with a mean of 53 mm Hg. Five patients lapsed into unconsciousness despite internal carotid stump pressures of 30, 30, 34, 36 and 70 mm Hg respectively, thus requiring intraoperativc shunting. This experience seriously questions the reliability of carotid stump pressure as the sole determinant to identify those patients who require intraoperative shunting. We have come full circle, back to operation under local anesthesia, since intraoperative assessment of the patients motor ability and consciousness alone provide the only absolute criteria for assessing the need for intraoperative shunting. Since the operation can be performed with greater technical efficiency without a shunt and without the potential complications of shunting itself, it behooves the surgeon to have a reliable method of knowing when it is not required.

Effect of Carbon Monoxide Exposure on Intermittent Claudication

The effect of breathing 50 ppm of carbon monoxide for two hours versus compressed, purified air for two hours on intermittent claudication was evaluated in ten men in a double-blind study. The mean venous carboxyhemoglobin level insignificantly decreased from 1.12% to 0.90% after breathing compressed, purified air but significantly increased from 1.08% to 2.77% after breathing carbon monoxide (P < 0.001). The mean exercise time until the onset of intermittent claudication insignificantly increased from 169 sec to 173 sec after breathing compressed, purified air but significantly decreased from 174 sec to 144 sec after breathing carbon monoxide (P < 0.001). Breathing 50 ppm of carbon monoxide for 2 hr significantly aggravated intermittent claudication of the calf or thigh due to angiographically documented occlusive arterial disease.

Carbon monoxide and ventricular fibrillation threshold in dogs with acute myocardial injury

In a blind, randomized study, the effect of breathing 100 p.p.m. of CO versus compressed, purified air for 2 hours on ventricular fibrillation threshold (VFT) was investigated in 21 dogs with acute myocardial injury. The mean arterial carboxyhemoglobin was 1.16 per cent in the air control period, 1.07 per cent after air, 1.08 per cent in the CO control period, and 6.34 per cent after CO. In comparison to air, CO increased the mean arterial carboxyhemoglobin (P less than 0.001). One dog developed spontaneous ventricular fibrillation 100 minutes after CO. Mean VFTs in the other 20 dogs were 12.8 +/- 6.8 milliamperes after CO, 11.2 +/- 6.0 milliamperes in the air control period, and 15.0 +/- 5.1 milliamperes after air. In comparison to air, CO decreased the VFT (P less than 0.001). These data show that breathing 100 p.p.m. of CO for 2 hours reduces the VFT in dogs with acute myocardial injury.

Heparinless left heart bypass for resection of thoracic aortic aneurysms

Our clinical experience employing heparinless left heart bypass for the resection of twenty-three thoracic aneurysms is presented. In our current technic of heparinless left heart bypass, plastic tubing coated with nonthrombogenic polyurethane-polyvinyl-graphite material and a conventional roller pump are employed. The reduced size of the aneurysm below the aortic clamp during bypass facilitates careful dissection of the aneurysm and the aorta. Twenty-two of twenty-three patients underwent successful thoracic aneurysmectomy with this technic. None had subsequent paraplegia and the postoperative blood loss was minimal. Heparinless left heart bypass is a simple and safe procedure to facilitate thoracic aneurysm resection.

Intestinal gangrene as the result of mesenteric arterial steal

Five cases of aortoiliac steal with gangrene of the bowel and death after aortoiliac reconstructive surgery are reported. In all five patients there was unrecognized preoperative evidence of severe impairment of the mesenteric circulation which should have led to mesenteric revascularization concomitant with aortoiliac reconstruction.

Redistribution of blood flow after carotid endarterectomy

PURPOSE We wanted to characterize the immediate effect of endarterectomy on flow of the arteries composing the extracranial carotid artery system. METHODS Transit time ultrasound probes were used to measure flow through the carotid bifurcation in 48 patients undergoing endarterectomy. Maximum single-diameter stenosis affecting the internal carotid artery (ICA) was determined by angiography. The significance of differences between means were determined by t tests and analysis of variance; linear and nonparametric correlation analyses were also applied to analyze the relation between stenosis and several flow-derived parameters. RESULTS Common carotid artery flow significantly increased (p = 0.0043) from a mean value of 264 +/- 99 ml/min to 314 +/- 98 ml/min, corresponding to an average percent increase of 34.3% +/- 71.3%. ICA flow increased from 128 +/- 69 ml/min to 173 +/- 66 ml/min (p < 0.0001), with an average percent increase of 74.9% +/- 114.9%. External carotid artery (ECA) flow decreased from 129 +/- 61 ml/min to 106 +/- 49 ml/min (p = 0.0098), representing an average percent decrease of -5.2% +/- 48.2%. The difference between ECA and ICA mean flow changes is highly significant (p < 0.001). The percent change in ECA flow did not correlate with preoperative stenosis. We noted, however, a positive correlation between stenosis and the ECA/ICA flow ratio before endarterectomy (Spearman r = 0.31, p = 0.032), indicating that more severe stenosis led to a greater distribution of blood into the ECA. The ECA/ICA flow ratio fell from an initial value (ECFbef/ICFbef) of 1.52 +/- 1.74 before endarterectomy to 0.69 +/- 0.37 (ECFaft/ICFaft) after endarterectomy (p = 0.0006). CONCLUSIONS The data are consistent, with the ECA being an important collateral path for cerebral perfusion when ICA stenosis exists. When endarterectomy relieves bifurcation stenosis, common carotid artery blood flow is redistributed preferentially to the ICA at the expense of ECA flow, consistent with a change in the relative resistances of the two vessels resulting from operative reconstruction.

Surgical management of coronary arterial disease in the elderly

Coronary artery angioplasty or bypass is being performed for increasing numbers of patients in their seventh, eighth, ninth and even tenth decades of life. Because of the costs involved, justification for performing these procedures in the elderly has become a topic for daily discussion among those responsible for funding healthcare. Both silent and overt coronary artery disease (CAD) are more common in the population over 65 years of age. Because CAD in the elderly often presents in an atypical manner, diagnosis of the disease is frequently delayed. Partly because of the delayed diagnosis and partly because of cost considerations, coronary arterial bypass (CABG) is more often performed as an emergency procedure in the elderly with the result that both operative mortality and costs are increased over those observed in a younger population. Nevertheless, it is clear that performance of coronary revascularization procedures in the elderly can both prolong life and improve the quality of life beyond what can be achieved using alternative methods of treatment. Greater efforts directed toward detection of ischemic heart disease in the these patients and earlier, elective surgery could significantly reduce both the mortality and disability associated with CAD in the elderly. Coronary Artery Dis 9:279–290

Reducing the noneducational and nonclinical workload of the surgical resident; defining the role of the health technician.

PURPOSE Recent controversy over excessive resident work hours has prompted surgical educators and program directors to search for more efficient methods to limit the nonclinical and noneducational workload of surgical residents. Health technicians were employed at a large Veterans Administration Medical Center to allow residents more time for direct patient care in the clinics and wards and in educational activities. METHODS In a two-week period, daily data cards were collected from each intern and health technician identifying total hours spent in work, operations, clinics, and conferences. Each intern recorded the number and type of tasks performed and those tasks assigned to the health technician. The number and type of task performed were tabulated and averaged for each health technician and physician. RESULTS Each intern (n = 3) and health technician (n = 8) completed 100% of the required data forms. In a control survey, each intern worked a mean of 16.9 hours per weekday and 5.0 hours per weekend day. With the addition of the health technicians, interns worked 12.9 hours per weekday and 6.8 hours per weekend day (when the health technicians were not present). Following the addition of the health technicians, resident time in the operating room increased from 3.3 hours per week to 9.8 hours per week. Each health technician aided the intern by performing an average of 20.25 tasks per day. CONCLUSIONS This study shows that health technicians can be effective in reducing the overall hours and workload of surgical residents and increasing time spent in the operating room. Consideration should be given to including the health technician as integral members of the health care team in the teaching hospital.