Echocardiography in patients with suspected endocarditis: a cost-effectiveness analysis.

PURPOSE: We sought to determine the appropriate use of echocardiography for patients with suspected endocarditis. PATIENTS AND METHODS: We constructed a decision tree and Markov model using published data to simulate the outcomes and costs of care for patients with suspected endocarditis. RESULTS: Transesophageal imaging was optimal for patients who had a prior probability of endocarditis that is observed commonly in clinical practice (4% to 60%). In our base-case analysis (a 45-year-old man with a prior probability of endocarditis of 20%), use of transesophageal imaging improved quality-adjusted life expectancy (QALYs) by 9 days and reduced costs by $18 per person compared with the use of transthoracic echocardiography. Sequential test strategies that reserved the use of transesophageal echocardiography for patients who had an inadequate transthoracic study provided similar QALYs compared with the use of transesophageal echocardiography alone, but cost $230 to $250 more. For patients with prior probabilities of endocarditis greater than 60%, the optimal strategy is to treat for endocarditis without reliance on echocardiography for diagnosis. Patients with a prior probability of less than 2% should receive treatment for bacteremia without imaging. Transthoracic imaging was optimal for only a narrow range of prior probabilities (2% or 3%) of endocarditis. CONCLUSION: The appropriate use of echocardiography depends on the prior probability of endocarditis. For patients whose prior probability of endocarditis is 4% to 60%, initial use of transesophageal echocardiography provides the greatest quality-adjusted survival at a cost that is within the range for commonly accepted health interventions.

Gastric intramucosal pH changes after volume replacement with hydroxyethyl starch or crystalloid in patients undergoing elective abdominal aortic aneurysm repair.

PURPOSE: Gastric intramucosal pH (pHi), a surrogate marker of tissue oxygenation, falls following abdominal aorta aneurysm (AAA) repair. We tested the hypothesis that volume replacement with a hydroxyethyl starch solution would result in better preserved splanchnic oxygenation than would volume replacement with crystalloid solutions. MATERIALS AND METHODS: This was a prospective, randomized, nonblinded study set in a university-affiliated community hospital. Thirty patients undergoing elective AAA repair were studied. Patients were randomly selected to receive intraoperative and postoperative fluid replacement with either hetastarch or crystalloid. According to the study protocol, patients could not receive in excess of 3,000 mL of hetastarch. Tissue oxygenation was assessed indirectly by measuring pHi using a nasogastric tonometer. Hemodynamic, oxygenation, and pHi data were collected preoperatively, preclamp, before unclamping, at the end of the procedure and postoperatively for 24 hours. Coagulation parameters were determined preoperatively and postoperatively for 24 hours. RESULTS: Fifteen patients were randomized to each group. There were 18 male and 12 female patients, whose mean age was 66 +/- 9 years. The intraoperative fluid balance was significantly greater in the crystalloid compared with the hetastarch group (4,194 +/- 1,500 mL v 2,949 +/- 1,123 mL; P = .05, 95% confidence interval [C] 23 to 2,519 mL). There were no significant differences in the amount of intraoperative blood loss or postoperative transfusion requirements between the two groups. The difference between the preoperative pHi and nadir was 0.07 +/- 0.03 in the hetastarch group compared with 0.13 +/- 0.04 in the crystalloid group (P = .001, Cl 0.03 to 0.09). By multivariate analysis the only variable that influenced the fall in pHi was the type of resuscitation fluid (F ratio of 7.63; P = .01). There were no significant differences in hemodynamic- and oxygenation-derived variables or coagulation parameters between the two groups of patients. The length of mechanical ventilation, intensive care unit, and hospital stay was comparable between the two groups of patients. CONCLUSION: In patients undergoing major surgery, volume resuscitation with hydroxyethyl starch solutions may improve microvascular blood flow and tissue oxygenation.

Gastrointestinal complications following cardiac surgery. An analysis of 1477 cardiac surgery patients.

OBJECTIVE: To determine preoperative and perioperative risk factors for gastrointestinal (GI) complications following cardiac surgery. DESIGN: A database including records of patients who underwent cardiac surgery was reviewed, with univariate analysis of several variables thought to be relevant to GI complications. Using a risk-adjusted model, preoperative stratification was used to fit a logistic regression model including operative features. SETTING AND PATIENTS: All patients undergoing cardiac surgery from January 1, 1991, to December 31, 1994, at a university-affiliated teaching hospital. MAIN OUTCOME MEASURES: Incidence of GI complications, postoperative mortality, length of hospital stay, and relative risk of GI complications based on multivariate analyses. RESULTS: Gastrointestinal complications occurred in 2.1% of patients and had an associated mortality of 19.4%; this was higher than the mortality in patients without GI complications (4.1%; P < .001). Length of hospital stay was significantly longer in patients with GI complications (43 vs 13.4 days; P < .001). In patients who underwent coronary artery bypass grafting only, cardiopulmonary bypass time was significantly longer in patients with GI complications (166 vs 138 minutes; P = .004). In patients who underwent valve replacement, bypass time was not associated with GI complications. Use of a left internal mammary artery graft was associated with a lower incidence of GI complications. CONCLUSIONS: Patients who have GI complications after cardiac surgery have a higher mortality and a longer hospital stay. The use of a left internal mammary artery seems to have a protective effect against GI complications. Based on these observations, patients may be stratified into low-, medium-, and high-risk groups.

The incidence of deep venous thrombosis in ICU patients.

STUDY OBJECTIVE: To determine the incidence, clinical presentation, and risk factors of deep venous thrombosis (DVT) in a high-risk group of ICU patients receiving DVT prophylaxis. DESIGN: A prospective cohort study. SETTING: Two ICUs of a university-affiliated teaching hospital. PATIENTS: Patients admitted to the ICUs within 48 h of hospitalization and who had an ICU stay of > or = 4 days underwent venous duplex scans. INTERVENTIONS: None. RESULTS: One hundred two patients were studied. Ninety-four (92%) patients received DVT prophylaxis. Twelve patients (12%) were documented to have DVT by venous duplex scans. There was proximal clot extension in eight of these patients, four of whom had high-probability ventilation/perfusion scans. Of the 56 patients without signs or symptoms of DVT, only two (3.6%) had abnormal scans. Leg swelling was present in 11 patients, six of whom had DVT (p = 0.004). One of 11 patients with unexplained fever had an abnormal scan. Five of the 26 patients (19%) receiving pneumatic compression developed DVT compared with five of 68 patients (7.4%) receiving subcutaneous heparin (not significant). No specific factor was identified that increased the risk of DVT. CONCLUSION: In this study, the incidence of DVT in a group of high-risk ICU patients receiving DVT prophylaxis was 12%. Since scans in patients without signs or symptoms suggestive of DVT were abnormal in only 3.6% of patients, venous scans should be performed only in patients with features suggestive of DVT or pulmonary embolism.

Outcomes and resource utilization in a managed care setting for lower extremity vein bypass grafts.

BACKGROUND: This 17-year review was undertaken to examine clinical outcomes and the changing trends in resource utilization for lower extremity bypass grafts performed in a managed care setting. PATIENTS AND METHODS: Between 1979 and 1995, 338 bypasses in 276 patients (199 men, 77 women; 62% diabetics) were carried out for limb salvage. Autogenous vein bypasses (AVB) were performed in 324 (96%) of the cases, which included 150 (43%) femoropopliteal (FP) and 174 (57%) femoro-tibial (FT) bypasses. There were 32 secondary AVB reconstructions included in the study group. RESULTS: The 30-day mortality rate was 2.2% and patient survival was 46% and 21% at 5 and 10 years. At 1 and 5 years, primary patency rates for the AVB were 87% and 79% for FP; 80% and 67% for FT AVB, whereas the limb salvage rates at those intervals were 96% and 94% for FP; 87% and 77% for FT, respectively. Despite an average annual inflation rate of 8%, significant reductions in hospital charges were noted during the study period. These were made possible by decreasing lengths of hospital stay, the development and application of guidelines and protocols for the management of leg ischemia, and the implementation of angioscopy for improving the surgical technique for in situ AVB. CONCLUSIONS: High-quality outcomes for lower extremity AVB are possible in a managed care setting with demonstrated improvements in the efficiency of resource utilization.

Laparoscopic adrenal surgery.

Laparoscopic adrenalectomy (LA) was performed in 6 patients (4 right and 2 left). A transperitoneal approach in a lateral position was used. Pheochromocytoma was present in two patients and Conn's syndrome, with a solitary functioning adenoma, was the diagnosis in four. Early vascular control was obtained in the two patients with pheochromocytoma, resulting in very stable intraoperative blood pressure. Operative time for LA was 152 +/- 26 min and was associated with a short length of stay (2.0 +/- 0.6 days) and minimal intraoperative blood loss (82 +/- 30 ml). There were no conversions to laparotomy and one complication was noted. LA is a safe and effective operation for patients requiring adrenalectomy for hormone-secreting tumors.

A comparison of four severity-adjusted models to predict mortality after coronary artery bypass graft surgery.

OBJECTIVE: To assess the validity of four severity-adjusted models to predict mortality following coronary artery bypass graft surgery by using an independent surgical database. DESIGN: A prospective observational study wherein predicted mortality for each patient was obtained by using four different published severity-adjusted models. SETTING: A university-affiliated teaching community hospital. PATIENTS: Eight hundred sixty-eight consecutive patients who underwent coronary artery bypass graft surgery without accompanying valve or aneurysm repair during the period from 1991 to 1993. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Predicted mortality rates for each model were obtained by averaging individual patient predictions and were compared with actual morality rates. We assessed the accuracy of overall prediction for the total series, as well as compared individual patient predictions created by each model. The discrimination of models was assessed with receiver operating characteristic curves and the Hosmer-Lemeshow goodness-of-fit statistic. RESULTS: The observed crude mortality rate was 3.7%. The predicted mortality rate ranged from 2.8% to 9.2%, despite relatively good discrimination by the models (area under the receiver operating characteristic curve, 0.70 to 0.74). The individual patient mortality predicted by different models varied by as much as a ninefold difference. CONCLUSIONS: The currently used coronary artery bypass graft predictive models, although generally accurate, have significant shortcomings and should be used with caution. The predicted mortality rate following coronary artery bypass graft surgery varied by a factor of 3.3 from lowest to highest, making the choice of model a critical factor when assessing outcome. The use of these models for individual patient risk estimations is risky because of the marked discrepancies in individual predictions created by each model.

A modified, angioscopically assisted technique for in situ saphenous vein bypass: impact on patency, complications, and length of stay.

PURPOSE: The impact of preoperative saphenous vein mapping and intraoperative angioscopy on the results of in situ saphenous vein bypass is analyzed in this study. METHODS: A new technique developed for in situ saphenous vein bypass (ISVB) was used in 26 patients (group I) and consisted of (1) preoperative duplex scanning and mapping of the saphenous vein and its tributaries, (2) small incisions for dissecting the proximal and distal arteries and veins, (3) ligation of marked tributaries through small incisions, (4) angioscopically directed incision of venous valves with a flexible-tipped valvulotome, and (5) femoral and distal anastomoses. The results were compared with those of 14 patients (group II) in whom the technique was similar except that venous tributaries were identified angioscopically and then ligated and 24 patients (group III) who underwent standard "open" ISVB through one long incision without angioscopy or vein mapping and in whom valvulotomy was carried out with a rigid valvulotome passed through tributaries. RESULTS: In comparing the results of groups I and III, significant reductions in operative intravenous fluid requirements (1930 ml vs 2675 ml; p = 0.04), postoperative length of stay (4.4 days vs 9.1 days; p < 0.001), and wound complications (1 vs 9; p = 0.01) were observed. Angioscopic irrigation fluid volume in group I was less than that in group II (360 ml vs 1014 ml; p < 0.001). At 12 months, the primary graft patency rate in all 64 patients was 91% for femoropopliteal and 89% for femoral-infrapopliteal ISBV and 84% for the 40 patients in groups I and II. CONCLUSIONS: This report demonstrates the effectiveness of our modified technique for ISVB, which helped reduce wound complications and length of stay while satisfactory early graft patency was also maintained.

Evaluation of right ventricular function during aortic operations.

The simultaneous measurements of mixed venous oxygen saturation (SvO2) and right ventricular ejection fraction (RVEF) have now made it possible to precisely define and correlate the various hemodynamic changes that occur during abdominal aortic operations. Twenty-five patients undergoing infrarenal abdominal aortic aneurysm repair were examined with a pulmonary artery catheter capable of continuously measuring SvO2 and RVEF. With aortic clamping, significant reductions in cardiac index, stroke volume index, and right ventricular end-diastolic volume index (RVEDVI) were noted, while RVEF remained unchanged. Following unclamping of the aorta, a significant reduction in SvO2 occurred, accompanied by an increase in mean pulmonary artery pressure and in pulmonary vascular resistance. Despite the increase in afterload, RVEDVI and RVEF did not change after unclamping. These preliminary data suggest that right ventricular function is preserved during abdominal aortic aneurysm repair.

Laparoscopic cholecystectomy. A clinical and financial analysis of 280 operations.

Two hundred eighty patients underwent laparoscopic cholecystectomy (LC) and were compared with 304 patients who underwent traditional "open" cholecystectomy (OC). Laparoscopic cholecystectomy was performed electively in 72.5% of cases and urgently in 27.5% of cases. Conversion from LC to OC was required in 14 patients (5%), six of whom required common bile duct exploration. Common bile duct stones were managed with video-laparoscopic techniques in 11 patients, with percutaneous transhepatic laser lithotripsy in three patients, and with laparotomy in six patients. Hospital stay was significantly shorter and complications were significantly fewer for LC compared with OC. Hospital expenses for LC were significantly higher than for OC because of longer duration of operation and higher operating room expenses. Patients who underwent elective LC returned to work an average of 31 days earlier than patients who underwent OC (10 days vs 41 days). These data indicate that LC can be performed safely although at a higher cost than OC, and that patients as well as employers benefit from a short length of hospital stay.

Continuous monitoring of mixed venous oxygen saturation during aortic operations.

OBJECTIVE: To systematically analyze the changes in mixed venous oxygen saturation (delta SvO2) during aortic operations with tube, aortobi-iliac, and aortobifemoral grafts. DESIGN: Survey of consecutive patients. SETTING: Teaching community hospital. PATIENTS: Thirty-one patients (22 male, 9 female, mean age 67 +/- 10 yrs), undergoing elective operations for aortic aneurysms (n = 25) and aortoiliac occlusive disease (n = 6). INTERVENTIONS: SvO2 was recorded throughout the operation. Cardiac output, mean pulmonary arterial pressure, arterial oxygen saturation (SaO2), and arterial pH were measured before and immediately after the unclamping of the aortic graft. RESULTS: In all patients, unclamping the aorta resulted in a marked reduction of mean SvO2, with no change in the cardiac output or SaO2. The unclamping of tube grafts was associated with a significant reduction in arterial pH (p less than .01) and in SvO2 (p less than .001), when compared with unclamping of bifurcation grafts. A significant (p less than .05) increase in mean pulmonary arterial pressure was observed after unclamping the aorta in patients with tube grafts. Despite a longer clamp time, unclamping the second limb of a bifurcation graft resulted in a smaller delta SvO2, when compared with that observed after unclamping the first limb (12% vs. 6%; p less than .01). The delta SvO2 after unclamping limb II was only 2% in aortobifemoral grafts and 9% in aortobi-iliac grafts. CONCLUSIONS: Reperfusion via extensive pelvic and lumbar collaterals in patients with aortoiliac occlusive disease reduces the delta SvO2 after aortic unclamping. Monitoring the changes in SvO2 during different types of aortic reconstruction helps to define precisely the physiologic alterations that occur in the course of these operations.

Laparoscopic common bile duct exploration.

Operative common bile duct exploration, performed in conjunction with cholecystectomy, has been considered the treatment of choice for choledocholithiasis in the presence of an intact gallbladder. With the advent of laparoscopic cholecystectomy, the management of common bile duct stones has been affected. More emphasis is being placed on endoscopic sphincterotomy and options other than operative common duct exploration. Because of this increasing demand, we have developed a new technique for laparoscopic common bile duct exploration performed in the same operative setting as laparoscopic cholecystectomy. A series of five patients who successfully underwent common bile duct exploration, flexible choledochoscopy with stone extraction, and T-tube drainage, all using laparoscopic technique, is reported. Mean postoperative length of hospital stay was 4.6 days. Outpatient T-tube cholangiography was performed in all cases and revealed normal ductal anatomy with no retained stones. Follow-up ranged from 6 weeks to 4 months, and all patients were asymptomatic and had normal liver function tests.

Carotid endarterectomy: a ten-year analysis of outcome and cost of treatment.

Between 1978 and 1988, 215 patients with an average age of 67 years, underwent 246 carotid endarterectomies. Two hundred ten (85.4%) patients were symptomatic, and 36 (14.6%) were asymptomatic. Six patients (2.4%) had a postoperative stroke, and all had immediate reoperation. One of these patients died (30 day mortality rate, 0.4% for the series), and two (0.8%) recovered completely, whereas three (1.2%) had a mild permanent neurologic deficit. Two patients (0.8%) had nonfatal myocardial infarction. Mean follow-up of 42.2 months (range, 1 to 126 months) was achieved. At 5 and 8 years actuarial survival rates of 82% and 66% and stroke-free survival rates of 67% and 37% were observed. Actuarial stroke free rates of 90% at 5 and 8 years were noted. By introducing and observing guidelines that required preoperative study of most clearly defined classes of patients before admission for surgical treatment, the average length of stay for carotid endarterectomy was lowered from 9.5 days in the first 5 years of the study to 5.8 days in the second 5 years (p = 0.001). Average hospital charges, expressed in constant dollars, decreased from $3113 in the first 5 years to $2620 in the second 5 years (p = 0.02) despite an 88% inflationary increase in medical consumer price index. This experience shows that the length of hospitalization of patients with carotid endarterectomy can be reduced and the cost of admission lowered without untoward effect on perioperative morbidity and mortality rates.

Comparison of effects of naloxone and catecholamines on acid-base balance in canine hemorrhagic shock.

The present study was conducted to compare the effect of naloxone, an opiate receptor antagonist, with catecholamines on acid-base status and survival in dogs subjected to hemorrhagic shock. Arterial lactic acid concentration which had increased during hemorrhage, decreased significantly (P less than 0.05) in naloxone treated animals but increased further in catecholamine treated dogs. Blood bicarbonate concentration and PCO2 which had markedly decreased 1 hr after hemorrhage recovered significantly (P less than 0.05) in naloxone group of animals. On the other hand bicarbonate and pH declined further in noradrenaline group and remained unchanged in dopamine group. These results as well as better survival rate observed in naloxone treated animals suggest the superiority of naloxone over dopamine and noradrenaline, as an adjunct to blood transfusion in the treatment of hemorrhagic shock.

Long latency cutaneous reflex effect on H-reflex recovery in hemiplegics and paraplegics: a longitudinal study for the assessment of motor function.

H-reflex recovery by twin pulses was recorded serially in 10 paraplegics for 5 months and in 23 hemiplegics for 2 months after the lesion. Fifty-one normal subjects acted as controls. The effect of cutaneous tactile stimulation was also studied simultaneously by applying electrical stimuli synchronized with twin pulses to the skin over the lateral border of small toe. In paraplegics, the H-reflex recovery curves recorded serially showed a highly depressed pattern during the first two weeks, an almost normal pattern during the second and third months and a significantly elevated pattern during the fourth and fifth months. Whereas cutaneous stimulation in control subjects produced a highly significant late inhibition of H-reflex recovery between 600 ms and 600 ms, in paraplegics it failed to produce any significant effect, except in two, who besides having a normal H-reflex recovery curve even during the first week, showed a substantial amount of cutaneous inhibition of H-reflex recovery, 4 months after the lesion. A highly depressed pattern of H-reflex recovery was observed on the affected side of the majority of hemiplegics during the first week after the lesion, many of them showing similar pattern on the "unaffected side" also. The serial study showed very good improvement in all hemiplegics both in terms of H-reflex recovery pattern and the amount of cutaneous inhibition. The observations in present study suggest preservation and/or restoration of supraspinal influences in many hemiplegics and in at least two paraplegics. The study also shows that a serial recording of H-reflex recovery curve and the amount of cutaneous reflex effect on it, is a very sensitive method of assessing the supraspinal influences on the spinal motoneurones and so can be of immense help in the diagnosis and prognosis in hemiplegics and paraplegics.

Lithium chloride SCN injection alters the circadian rhythm of food intake.

Effect of lithium injections through chronically implanted cannulae into the bilateral suprachiasmatic nuclei (SCN) on the circadian rhythm of food intake was investigated in the rat. It was observed that the circadian rhythm was disrupted by injections of lithium at the beginning of the light as well as the dark phase of the LD cycle. In either case the percentage of the food consumed during the 12-hr light period increased while that during the dark period decreased without any significant change in the total daily intake. Disruptions in the circadian rhythm of food intake failed to show any dose-response relation. Injections of saline into the SCN or lithium into the nearby SCN area did not produce a disruption of the circadian rhythm of food intake.

Long latency inhibition of H-reflex recovery by cutaneous tactile stimulation in man: a cutaneous transcortical reflex.

The effect of cutaneous tactile stimulation on motoneuron excitability was studied in 20 normal subjects and in patients of hemiplegia (n = 14) and paraplegia (n = 15) by plotting H-reflex recovery curves during application of twin pulses alone ("basal" H-reflex recovery curve), and twin pulses synchronized with electrical stimuli evoking tactile sensation in skin over the lateral border of the small toe. The "basal" H-reflex recovery curves from normal subjects showed a significant lateral asymmetry of motoneuron excitability, with an even distribution of subjects showing greater excitability on the left and right sides. However, there was no relation between handedness and the side with greater excitability. The cutaneous stimulation produced a highly significant inhibition of the H-reflex recovery between 600 and 6000 ms, with the maximum inhibition recorded at 1000 and 2000 ms, at which time even a complete inhibition of the test H-reflex was observed in some instances. The effect of cutaneous stimulation before 600 ms was statistically insignificant. The amount of cutaneous inhibition of H-reflex recovery showed a lateral asymmetry. The side with greater motoneuron excitability showed more cutaneous inhibition of the H-reflex recovery. A comparison of the H-reflex recovery at higher frequencies of cutaneous stimulation with that at basal frequency showed a slight but statistically insignificant difference in the amount of cutaneous inhibition of the H-reflex recovery. In hemiplegics, the "basal" H-reflex recovery curves showed greater motoneuron excitability on the affected side as compared to those of the unaffected side or controls, with the late inhibitory phase being completely obliterated. A similar pattern was also observed in paraplegics. Significantly, the lateral asymmetry of motoneuron excitability observed in the control group was absent in paraplegics. The cutaneous stimulation failed to produce any significant effect on the H-reflex recovery curves either in the affected side of hemiplegics or in both sides of paraplegics. The significant long latency inhibition of the H-reflex recovery curve produced by cutaneous tactile stimulation is a new finding.(ABSTRACT TRUNCATED AT 400 WORDS)