Monitoring equipment induced tachycardia in patients with minute ventilation rate-responsive pacemakers.

Minute ventilation-sensing pacemakers enable the paced heart to respond to an increased workload. Two patients with such a pacemaker developed pacemaker-driven tachycardia when connected to an electrocardiogram (ECG) monitor also capable of documenting ventilatory frequency and ECG lead disconnection. This tachycardia stopped when the ECG leads were removed. These pacemakers and monitors emit a low-amplitude electrical current and measure the resultant impedence signal across the chest. When patients are connected to the monitor the pacemaker sensor summates both impedence signals and the paced heart rate is increased as a result.

History of the development of antiemetic guidelines at Mayo Clinic Rochester.

This article describes the historic experience of the development of antiemetic guidelines for patients taking chemotherapy drugs at Mayo Clinic Rochester. The initial guidelines for the use of serotonin (5-hydroxytryptamine3) receptor antagonists for the prevention of chemotherapy-induced nausea and vomiting were developed in early 1995 and implemented in September 1995. In February 1997, the guidelines were reviewed and modified. In the spring of 1998, major changes were made based on new data from the literature and discussions with antiemetic authorities in the United States. These guidelines were implemented in July 1998. The guidelines were again reviewed and modified in December 1998. In addition, we compared costs associated with the 1997 guidelines and the December 1998 guidelines. The developed guidelines, utilizing clinically available agents, seem to provide high-quality patient care at a reasonable cost.

Assessment of prediction of mortality by using the APACHE II scoring system in intensive-care units;.

Some investigators have suggested that information on quality of care in intensive-care units (ICUs) may be inferred from mortality rates. Specifically, the ratio of actual to predicted hospital mortality (A/P) has been proposed as a valid measure for comparing ICU outcomes when predicted mortality has been derived from data collected during the first 24 hours of ICU therapy with use of a severity scoring tool, APACHE II (acute physiology and chronic health evaluation). We present a comparison of mortality ratios (A/P) in four ICUs under common management, in two hospitals within a single institution. Significant differences in A/P were detected for nonoperative patients (0.99 versus 0.67;P = 0.014) between the two hospitals. This variation was traced to uneven representation of a subset of patients who had chronic health problems related to diseases that necessitated admission to the hematology-oncology or hepatology service. No differences in A/P were seen between the two hospitals for operative patients or for nonoperative patients on services other than hematology-oncology or hepatology. Thus, differences in A/P detected by using the APACHE II system not only may reside in operational factors within the ICU organization but also may be related to weaknesses in the APACHE II model to measure factors intrinsic to the disease process in some patients. We suggest that case-mix must be examined in detail before concluding that differences in A/P are caused by differences in quality of care.

Pancreas transplantation at Mayo: II. Operative and perioperative management.

Better perioperative and operative management techniques have contributed to an improvement in the success rate of pancreas transplantation. Because of a shortage of donor organs, the criteria for acceptability of the allograft have been liberalized, and the development of techniques such as combined liver and pancreas procurement has increased allograft availability. Major advances have been made in organ preservation. Currently, pancreas allografts can routinely be stored for 18 to 24 hours. The technique of pancreaticoduodenal transplantation with a duodenocystostomy for the exocrine drainage is widely used. Experience with anesthetic and intensive-care unit management of these patients is accumulating. With the evolution of pancreas transplantation and with the help of the excellent transplant centers in our area, we developed a pancreas transplantation protocol and performed transplantation based on this protocol in 16 recipients at the Mayo Clinic from October 1987 through December 1988.

Intensive-care unit experience in the Mayo liver transplantation program: the first 100 cases.

The first 100 liver transplantations at the Mayo Clinic were performed in 83 patients, who required a total of 917 patient days in the intensive-care unit (ICU). The mean duration of stay in the ICU was 5.91 days after liver transplantation and 6.15 days for patients who subsequently required readmission to the ICU. During the immediate postoperative period, hypothermia and hyperglycemia invariably occurred. Later during the initial admission or on readmission to the ICU, there arose the possibility of infections and renal insufficiency. Prompt diagnosis and treatment are necessary for hypertension, hypokalemia, severe metabolic alkalosis, fever, altered mental status, oliguria, and signs of graft failure in liver transplant patients. In our patient series, selective bowel decontamination minimized the occurrence of gram-negative and fungal sepsis, and use of antihypertensive agents and correction of coagulopathies may have decreased the risk of intracranial bleeding in patients with hypertension and clotting defects. Anticipation of potential conditions postoperatively and early implementation of treatment are key factors in the successful ICU management of patients who have undergone liver transplantation.

Comparison of analgesic requirements after liver transplantation and cholecystectomy.

In a prospective study of 10 patients who underwent liver transplantation and 10 patients who underwent cholecystectomy, we analyzed the postoperative analgesic requirements and the resultant plasma morphine concentrations. Analgesia was more intense, with less medication, and the plasma morphine concentration was significantly lower in the liver transplant group than in the cholecystectomy group. This finding is most likely attributable to endogenous factors rather than to altered morphine pharmacokinetics.

Assessment of nutritional status of patients with end-stage liver disease undergoing liver transplantation.

Nutritional assessment factors (including dietary history, anthropometric and biochemical measurements, and evaluation of immunocompetence) were retrospectively reviewed in 74 patients undergoing an initial liver transplantation procedure. The patients were subdivided into four categories on the basis of type of liver disease: chronic active hepatitis (N = 24), primary sclerosing cholangitis (N = 22), primary biliary cirrhosis (N = 20), and acute or subacute hepatitis (N = 8). Our nutritional assessment data indicated that malnutrition was present preoperatively in all liver transplantation groups but that each group had distinct characteristics. The group with primary biliary cirrhosis seemed to have the best hepatic synthetic function despite extreme wasting of muscle and fat. On the basis of all criteria, the group with acute hepatitis was the most malnourished of the various disease groups. Aggressive nutritional support, which includes adequate intake of nutrients and supplementation of vitamins and trace minerals, should be encouraged for all potential liver transplant patients.

The first 100 liver transplantations at the Mayo Clinic.

Between March 1985 and June 1987, the first 100 liver transplantations at the Mayo Clinic were performed in 83 patients (primarily adults). The most frequent diagnoses were chronic active hepatitis (in 24 patients), primary sclerosing cholangitis (in 22), and primary biliary cirrhosis (in 20). The median operating time was 406 minutes, and the median usage of erythrocytes was 13.2 units. A venovenous bypass was used in all patients older than 10 years of age. Hepatic artery thrombosis occurred in 10% of the 100 transplants. A choledochocholedochostomy was done in 58 patients and a choledochojejunostomy in 25 patients. Revision of the biliary anastomosis was necessary in 9 of the 83 patients (11%). Rejection, diagnosed by clinical and histologic criteria, occurred in 50 patients (60%) and was treated with a corticosteroid bolus, followed by OKT3 (monoclonal antibody) treatment if necessary. Selective bowel decontamination helped prevent infections; only 16 bacteremias occurred, 1 of which was caused by a gram-negative organism. Fungal infections were rare. Cytomegalovirus infection occurred in 47 patients (57%). Of the 83 patients, 16 required retransplantation, in 11 of whom graft rejection had occurred. One- and 2-year patient survival was 83% and 70%, respectively. Although problems still remain, liver transplantation is a reasonable option for patients with end-stage liver disease.

Free radicals in medicine. II. Involvement in human disease.

This review explores evidence that free radicals might be involved in various human disease processes. Such involvement is difficult to prove because direct evidence is often lacking and is based on animal models of the disease process. Evidence for free radical involvement includes demonstrating abnormal free radical production in the disease, finding that deliberately applying free radical-producing systems into the cellular locus responsible for the disease reproduces its manifestations, and showing that free radical scavengers control facets of the disease process. Confirmation of free radical involvement in a particular disease may have clinical relevance, inasmuch as clinically applicable techniques are currently being developed to remove free radicals from cellular sites where they are injurious and, in other situations such as chemotherapy, techniques or drugs that produce free radicals are available to destroy harmful cells.

Free radicals in medicine. I. Chemical nature and biologic reactions.

Free radicals are reactive chemical species that differ from other compounds in that they have unpaired electrons in their outer orbitals. They are capable of damaging cellular components, and accumulating evidence suggests they may contribute to various disease entities. Biologic systems are exposed to free radicals that have been formed endogenously or that result from external influences such as ionizing radiation. Oxygen free radicals are continuously being produced intracellularly by oxidation-reduction reactions. The sequential univalent reduction of molecular oxygen initially forms the superoxide anion radical, which in turn is converted, in the presence of transition metal ions, into the highly reactive hydroxyl radical. Free radicals are detected by electron spin resonance spectroscopy, but often this procedure is difficult to use for study of free radical involvement in biologic systems, and investigators have resorted to inferring their presence by identifying the products of free radical reactions. All aerobic organisms possess substances that help prevent free radical-mediated injury. These include antioxidants such as vitamin E and the enzymes superoxide dismutase and glutathione peroxidase. A second part of this review will describe the role of free radicals in specific disease entities.

Respiratory failure in Lambert-Eaton myasthenic syndrome.

Five patients with the Lambert-Eaton myasthenic syndrome who required more than 48 hours of mechanical ventilation for respiratory failure are described. All five had small cell bronchogenic carcinoma. In one patient with associated chronic bronchitis, one with interstitial pulmonary fibrosis, and one other, respiratory failure requiring mechanical ventilation developed as a result of the Lambert-Eaton myasthenic syndrome. The two other patients had received muscle relaxant drugs, but the acute respiratory failure episode in one of the two was not clearly related to their administration. One patient had an initial response to plasmapheresis, which allowed assisted mechanical ventilation to be discontinued. This improvement was not sustained, and the patient subsequently died in respiratory failure. Three patients survived to be dismissed from the hospital after they were weaned from mechanical ventilation.

Adverse effects of vancomycin administered in the perioperative period.

Indications for the administration of vancomycin in the perioperative period have expanded in recent years. Used in this situation, vancomycin has caused adverse reactions, the most serious of which is hypotension. We describe five patients who had adverse reactions to vancomycin perioperatively. Vancomycin-induced hypotension usually results from a negative inotropic and vasodilator effect produced in part by a histamine-release phenomenon, which occurs most commonly with rapid intravenous infusion of the drug. Such a release of histamine may also produce an acute urticarial flushing of the upper torso (the "red neck syndrome") and symptoms of pain and muscle spasm in the chest or paraspinal muscles, which may mimic myocardial infarction. These effects usually abate promptly when the infusion of vancomycin is discontinued, and their resolution may be expedited by administration of an antihistamine.

Treatment of tetanus-induced autonomic nervous system dysfunction with continuous epidural blockade.

A patient with tetanus had a labile blood pressure caused by marked fluctuations in systemic vascular resistance. During hypotensive episodes, mixed venous oxygen saturation decreased below 60%. Hemodynamic instability was controlled after institution of a continuous lumbar epidural local anesthetic block.

Differential mechanical ventilation in respiratory failure due to severe unilateral lung disease.

Severe unilateral lung disease that produces respiratory failure may necessitate mechanical ventilatory support to sustain gas exchange. This article describes the successful use of differential lung ventilation in the management of one patient with diffuse unilateral pneumonia and another with a postoperative bronchopleural fistula after standard methods of mechanical ventilation failed to provide adequate gas exchange for these patients.

Pleural liquid pressure measured by micropipettes in rabbits.

Pleural liquid pressure (Ppl) was measured by the micropipette servo-nulling method. In anesthetized, paralyzed, and mechanically ventilated rabbits, windows were made by dissecting away the intercostal muscle layers, exposing the parietal pleura over the right caudal lung lobe. Repeated measurements of Ppl were made at the windows by puncturing the parietal pleura with micropipettes during apnea at functional residual capacity. In five supine rabbits, Ppl relative to atmospheric pressure averaged -3.32 +/- 1.22 (SD) cmH2O at a distance of 5.64 +/- 0.34 (SD) cm above the lung base and -1.64 +/- 0.79 cmH2O at a distance of 2.35 +/- 0.64 cm above the lung base; the vertical Ppl gradient was 0.51 cmH2O/cm height. Ppl interpolated to midlung height was equal in absolute magnitude to mean lung static recoil (Pst) of 2.00 cmH2O. In prone rabbits, Ppl measured near the dorsal surface, 3.9 cm above the lung base, averaged -1.32 +/- 0.46 cmH2O on the costal surface, not statistically different in magnitude from mean Pst of 1.59 +/- 0.09. In contrast, Ppl measured at the same vertical height off the edge of the caudal lung in the costo-diaphragmatic recess was -4.64 +/- 0.65 cmH2O. We concluded from these data that Ppl was equal to pleural surface pressure over the costal surface and that the vertical gradient in Ppl was not hydrostatic, except in large fluid spaces off the sharp edges of the lung.