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Biomedical subjects

P Calhoun

Publications and source records attributed to P Calhoun.

12 recordsLinked to original sources
PubMed1999

Tracheal extubation of deeply anesthetized pediatric patients: a comparison of isoflurane and sevoflurane.

UNLABELLED: We studied the emergence characteristics of unpremedicated children tracheally extubated while deeply anesthetized ("deep extubation") with isoflurane or sevoflurane. Forty children were assigned to one of two groups, Group I or Group S. At the end of the operation, Group I patients were extubated while breathing 1.5 times the minimum alveolar anesthetic concentration (MAC) of isoflurane. Group S patients were tracheally extubated while breathing 1.5 times the MAC of sevoflurane. Recovery characteristics and complications were noted. Group S patients were arousable sooner than Group I patients (10.1 + 6.5 vs 16.3 + 9.9 min). Later arousal scores and times to discharge were the same. There were no serious complications in either group. Breath-holding was more common in Group I. We conclude that the overall incidence of airway problems and desaturation episodes was similar between groups. Emergency delirium was common in both groups (32% overall: 40% for Group I, 25% for Group S). IMPLICATIONS: Deep extubation of children can be safely performed with either isoflurane or sevoflurane. After deep tracheal extubation, airway problems occur but are easily managed. Return to an arousable state occurred more quickly with sevoflurane, although time to meeting discharge criteria was not different between the two groups. Emergence delirium occurs frequently with either technique.

Adolescent↗
PubMed1994

Epidural morphine combined with epidural or intravenous butorphanol for postoperative analgesia in pediatric patients.

We performed a prospective, randomized, double-blinded study in 60 postoperative pediatric patients aged 6 wk to 7 yr to compare the efficacy of butorphanol given epidurally or intravenously in preventing the side effects of epidural morphine. Three groups of patients received 60 micrograms/kg epidural morphine; 20 patients also received epidural butorphanol 30 micrograms/kg, and 20 patients also received 30 micrograms/kg intravenous butorphanol. All patients were evaluated for analgesia, sedation, vomiting, urinary retention, pruritus, and respiratory depression for 24 h postoperatively. Although the overall incidence of side effects was not different in the three groups, the epidural butorphanol group had a significant decrease in severity of pruritus. Sedation was seen more frequently in the groups receiving butorphanol, but was most pronounced in the epidural butorphanol group. We conclude that butorphanol has little or no effect on the side effects of epidural morphine.

Butorphanol↗
PubMed1987

Experimental studies of biliary excretion of piperacillin.

The nonrecirculating isolated perfused rat liver was used to study biliary antibiotic excretion by the liver in a steady-state, controlled environment in which bile flow, bile salt output, and antibiotic delivery were maintained under constant conditions. The effects of piperacillin, ampicillin, and gentamicin on bile flow and bile salt output were analyzed; none altered bile salt output, and only high concentrations of piperacillin (100 micrograms/mL) increased bile flow. The ratio of antibiotic concentration in bile and perfusate depended on the type of antibiotic and perfusate concentration. Piperacillin infusions at perfusate concentrations of 50 or 100 micrograms/mL (in the presence of 60 microM taurocholate) yielded bile to perfusate ratios of 112 +/- 10 versus 49 +/- 3, respectively. Using similar perfusate, the concentration ratios for ampicillin (20 micrograms/mL) and gentamicin (10 micrograms/mL) were only 3.4 +/- 0.5 and 0.5 +/- 0.1, respectively. By altering the perfusate to contain either 60 microM or 240 microM taurocholate, we found variance in bile salt output from 27 +/- 1 to 115 +/- 2 mumol/h, yet this alteration had little effect on the output of ampicillin (perfusate concentration of 20 micrograms/mL), 73 +/- 7 versus 74 +/- 12 micrograms/h, or piperacillin (perfusate concentration 100 micrograms/mL), 10 +/- 1 versus 11 +/- 2 mg/h. Thus, it appears ampicillin and piperacillin are excreted into bile at high concentrations by bile salt-independent pathways. Partial biliary obstruction (6 cm H2O) results in significant decreases in bile volume. Infusion of 50 micrograms/mL of piperacillin resulted in increased biliary flow that approached nonobstructed values. Obstruction resulted in significant decreases in bile piperacillin concentration. Whether the choleretic effect of high concentrations of piperacillin has any clinical significance in nonobstructed or obstructed conditions remains to be established.

Ampicillin↗
PubMed1986

The clinical outcome of needle aspirations of the lung when cancer is not diagnosed.

One hundred thirty-two of 397 consecutive percutaneous fine needle aspirations done at the University of Virginia between January, 1979, and December, 1984, for pulmonary lesions showed no evidence of cancer on cytological examination. We reviewed the presenting symptoms, radiographic findings on the day of needle aspiration, and the descriptive cytological terms to determine if it was possible to distinguish benign from malignant disease in these 132 patients. We found a specific benign diagnosis in only 16 (12%) of the 132 patients, and 1 of them ultimately was found to have cancer. In the remaining 116 patients, analysis of age, sex, smoking history, presenting symptoms, radiographic findings at the time of needle aspiration, and cytological terms other than malignancy did not enable distinction of benign from malignant disease as the cause of the radiographic finding. In the group of 132 patients without suggestion of cancer on initial cytological study, 38 (29%) were subsequently found to have a malignant process.

Adolescent↗
PubMed1986

Evaluation of insulin secretion after pancreas autotransplantation by oral or intravenous glucose challenge.

Segmental pancreatic autotransplantation is accompanied by surgical alterations to the pancreas that may have consequences for carbohydrate metabolism. Four mongrel dogs were evaluated before operation and sequentially until 40 weeks after total pancreatectomy and autotransplantation of the splenic lobe of the pancreas with bolus intravenous and oral administration. Intravenous glucose tolerance test (IVGTT) (0.5 g/kg) revealed maintenance of fasting euglycemia for as long as 40 weeks after operation. Peak glucose and integrated glucose values did not show significant changes as a result of autotransplantation. Following transplantation, a delayed peak insulin response was seen; however, basal, peak, and integrated insulin values were largely unaltered. Only K values, a measure of glucose disposal, showed severe alterations (2.44 +/- 0.21 before operation to 1.24 +/- 0.30 at 40 weeks after operation). Oral glucose tolerance tests (OGTT) (2.0 g/kg) demonstrated an increased peak hyperglycemic response after autotransplantation with increased integrated glucose responses. Insulin levels remained at those levels seen before operation, and glucose-dependent insulinotropic polypeptide (GIP) responses were unchanged during the OGTT as late as 20 weeks after operation. In conclusion, pancreas autotransplantation after total pancreatectomy results in significant metabolic alterations that the IVGTT fails to detect with absolute glucose or insulin levels. However, K values are significantly lowered, which indicates alterations in cellular glucose transport. The OGTT demonstrates hyperglycemia without increased insulin or GIP levels, which suggests an altered beta cell response to the enteric stimulus of insulin release. These changes are nonetheless well tolerated by animals that have remained clinically healthy and euglycemic in the basal state.

Animals↗
PubMed1984

Postoperative recurrence in Crohn's disease. The effect of the initial length of bowel resection and operative procedure.

We reviewed the surgical experience of 61 patients with Crohn's disease who have received surgical treatment over a 32-year period. Sex, age at onset of symptoms, associated systemic abnormalities, presenting symptoms, indication for previous surgery, and site of disease were not significant predictors of postoperative recurrence. Certain extensive resections of the small bowel are associated with a decreased probability of rehospitalization and reoperation. Resection of more than 25 cm of the small bowel and more than 50 cm of the "total" (small plus large) bowel was associated with a decreased likelihood of recurrence. Interestingly, analysis of larger resections (50, 75, 100 cm) failed to document a decreased likelihood of recurrence. The amount of large bowel resected did not predict postoperative recurrence. Bypass and diversion procedures offer a significantly enhanced risk for recurrent disease, whereas procedures employing resection are associated with lower probabilities of recurrent disease. We conclude that technically adequate resections of 25 to 50 cm of the small bowel or the combined small and large bowel are associated with a decreased probability of reoperation or rehospitalization after the initial surgery for Crohn's disease.

Adolescent↗
PubMed1984

Hormonal contributions to biliary secretion.

Gastrointestinal hormones appear to be important modulators of bile flow and composition. Insulin and glucagon induce choleresis at physiologic levels and may alter lipid output and concentration as well. The effects of many hormones such as insulin, glucagon, secretin, and pancreatic polypeptide are at least partially independent of their effects on neurovascular factors. Furthermore, recently studied hormones such as somatostatin, vasoactive intestinal polypeptide, and pancreatic polypeptide have also been shown not only to alter bile flow but to affect bile composition. Understanding the role of gastrointestinal hormones in hepatic physiology may elucidate the causes of gallstone formation, disorders of biliary excretion, and hypercholesteremic states.

Animals↗