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Biomedical subjects

R I Hall

Publications and source records attributed to R I Hall.

At least 55 records · Page 3Linked to original sources
PubMed1991

Less than additive antinociceptive interaction between midazolam and fentanyl in enflurane-anesthetized dogs.

The anesthetic interactions of midazolam and fentanyl were determined in terms of enflurane MAC reduction in dogs. In part 1, 8 animals received an intravenous (iv) loading dose of fentanyl followed by a constant infusion at 0.05 micrograms.kg-1.min-1 to produce a stable enflurane MAC reduction of approximately 20%. Midazolam was then administered in a series of three incremental loading doses and infusions (2.4, 9.6, and 28.8 micrograms.kg-1.min-1 previously determined to produce enflurane MAC reductions of approximately 30, 45, and 60%, respectively. Enflurane MAC was determined for each infusion. Then fentanyl was discontinued; naloxone 1 mg/kg was administered; and enflurane MAC was determined. In part 2, six dogs received a loading dose and a continuous infusion of fentanyl (0.2 micrograms.kg-1.min-1) designed to produce a stable enflurane MAC reduction of approximately 40%. A series of two incremental loading doses and infusions of midazolam (2.4 and 28.8 micrograms.kg-1.min-1) were added, and MAC determinations were repeated at each infusion rate. Then midazolam was discontinued; flumazenil (RO 15-1788) 1.5 mg/kg was administered; and enflurane MAC was determined. The fentanyl concentrations in plasma remained stable at 1.0 +/- 0.3 ng/ml (mean +/- standard deviation [SD], part 1) and 3.1 +/- 0.5 ng/ml (part 2) throughout the study and, in the absence of midazolam, reduced enflurane MAC by 28 +/- 11 and 44 +/- 5%, respectively. The addition of midazolam produced significant further reductions in enflurane MAC, but the reductions were less than those predicted on the basis of an additive interaction. Naloxone returned enflurane MAC reduction to that expected for midazolam alone (part 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1991

Assessing the adequacy of fentanyl anesthesia: plasma concentrations and lower esophageal contractility.

Assessing the adequacy of anesthesia in the paralyzed patient is usually based on sympathetic and hemodynamic responses to noxious stimulation. Absence of such responses does not guarantee adequate anesthesia. A device monitoring the amplitude of provoked lower esophageal, contractility (PLEC) and the rate of spontaneous lower esophageal contractility (SLEC) has been developed as a potential monitor of the adequacy of anesthesia. This study determined the reliability of this device for monitoring anesthetic depth in 20 patients receiving fentanyl infusions who were undergoing coronary artery surgery and who were hemodynamically stable in the preoperative period. Premedication included midazolam 0.05 mg/kg i.m. and ranitidine 2 mg/kg p.o. Anesthesia was induced with fentanyl 50 micrograms/kg administered over 10 min and maintained by a fentanyl infusion 0.2 micrograms.kg-1.min-1. Following endotracheal intubation, a disposable esophageal monitoring probe, equipped with provoking and measuring balloons, was inserted and both the amplitude of provoked (PLEC) and the rate of spontaneous lower esophageal contractions (SLEC) were displayed and recorded. Precisely defined clinical signs of inadequate anesthesia included both somatic and hemodynamic responses to noxious stimulations. The presence of these responses was correlated with PLEC and SLEC and with fentanyl concentrations in plasma at specific times of noxious stimulation during the period preceding initiation of cardiopulmonary bypass. A total of 208 episodes of noxious stimulation were recorded at insertion of the nasal temperature probe (n = 8), at penetration of the skin by towel clips (n = 25), at skin incision (n = 20), at sternotomy (n = 20) and during multiple episodes of electrocauterization (n = 135). These provoked 52 clinical responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1990

Pancreatic exocrine function after a sutureless pancreatico-jejunostomy following pancreaticoduodenectomy.

Exocrine pancreatic function was measured in 14 patients after pancreaticoduodenectomy for periampullary neoplasms in order to assess the patency of a sutureless pancreatico-enteric anastomosis. Pancreatic function was examined by the p-aminobenzoic acid/p-aminosalicylic acid (PABA/PAS) test 3-160 months after operation and compared with age- and sex-matched controls. There were no significant differences between mean (s.e.m.) serum PABA concentrations 3 h after ingestion of N-benzoyl-L-tyrosyl-PABA (25.5 (3.6)) mumol/l for patients, 26.1 (2.0) mumol/l for controls). However, the mean (s.e.m.) PABA excretion index was significantly lower in the patients (0.58 (0.08)) than in the controls (0.76 (0.04)). Four patients required pancreatic enzyme supplements for control of diarrhoea. Self-limiting pancreatic leaks occurred in two patients. The results suggests that the sutureless pancreatico-enteric anastomosis has an acceptably low leakage rate but that pancreatic exocrine function is diminished following pancreaticoduodenectomy with this technique. However, the majority of patients require no enzyme supplements and no significant tendency to late stenosis of the anastomosis was demonstrated.

4-Aminobenzoic Acid↗
PubMed1990

The benefit of the Hemonetics cell saver apparatus during cardiac surgery.

This retrospective chart review of 155 patients having coronary artery bypass graft surgery (CABG) over a two-month period determined whether the use of a cell saver apparatus (CSA) (1) reduced or increased the requirements for homologous blood; (2) increased the incidence of post-surgical bleeding; (3) was cost-effective. Two groups of patients were identified. Group 1 (n = 99) received both CSA processed red blood cells and homologous blood components. Requirement for homologous blood products was reduced in the first 24 hr after surgery (0.5 +/- 1.0 vs 1.3 +/- 1.8 units; P less than 0.05) when compared with Group 2 (n = 56) in whom only homologous blood products were utilized. More patients in Group 1 had no transfusion requirements (45 vs 8; P less than 0.05) and there was no increased risk of major haemorrhage. When the capital costs are included, utilization of the CSA was not cost-effective. We conclude that utilisation of a CSA was safe, with no increased risk of bleeding, reduced requirements for homologous blood transfusions, but added to the cost of the procedure.

Blood Transfusion↗
PubMed1990

Cellular and muscle zinc in surgical patients with and without gastrointestinal cancer.

1. The zinc status of surgical patients with and without gastrointestinal cancer was studied. 2. Plasma zinc was lowest in patients with cancer concurrent with depressed plasma albumin concentrations. 3. Polymorphonuclear cell zinc was decreased in both patient groups and correlated strongly with abdominal muscle zinc (r = 0.89, P less than 0.001). 4. Mononuclear cell and total leucocyte zinc were similar to control values in both groups of patients. Total leucocyte, but not mononuclear cell, zinc correlated weakly with muscle zinc (r = 0.48, P less than 0.05). 5. The results suggest that polymorphonuclear cell zinc may be better than leucocyte zinc in assessing zinc status and that some surgical patients may be zinc-depleted. The presence of gastrointestinal cancer did not influence the zinc status.

Adult↗
PubMed1990

Periampullary diverticula predispose to primary rather than secondary stones in the common bile duct.

Periampullary duodenal diverticula are known to be associated with an increased incidence of common bile duct stones. The nature of the association with gallstones remains uncertain. We have examined the incidence of periampullary diverticula and stones after cholecystectomy to determine whether the stones originate primarily in the common duct or migrate from the gallbladder under the influence of abnormal biliary motility. Six hundred and forty-one patients undergoing ERCP were studied. Ninety-five patients had diverticula (14.8%). Diverticula occurred more commonly in jaundiced patients, 47/95, (48.4%) than in patients with normal bilirubin 185/546 (33.8%) (p less than 0.01). Common duct stones were associated with the presence of a diverticulum in 41/95 patients (43%), compared with only 98/546 without a diverticulum (18%) (p less than 0.001). There was no difference in the incidence of common duct stones in association with a diverticulum between those who had had a cholecystectomy 20/41, and those with intact gallbladders, 21/54 (N.S.). Thus the absence of a gallbladder did not alter the high incidence of common duct stones. We conclude that the stones in the common duct are most likely to be primary stones which have formed as a result of periampullary dysfunction.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1990

Does cardiopulmonary bypass alter enflurane requirements for anesthesia?

This study on dogs determined whether the requirement for enflurane anesthesia was different pre- versus postcardiopulmonary bypass (CPB). Male mongrel dogs (n = 16) were anesthetized with enflurane in oxygen. Tracheal intubation was performed, monitors placed, and end-tidal enflurane concentration measured via a Puritan-Bennett Anesthesia Agent Monitor. MAC was determined by the tail-clamp method. CPB was then initiated using aortoatrial (n = 6, group 1) or femoral artery-vein (n = 4, group 2) cannulation or none (n = 6, group 3, control). CPB was maintained for 1 h using a bubble oxygenator, a crystalloid prime, and flows of approximately 70-80 ml/kg with a mean systemic pressure maintained between 50-70 mmHg. Following separation from CPB, MAC was again determined. The reduction in enflurane MAC following CPB was 30.1 +/- 21.5% (mean +/- SD; P less than 0.05 vs. pre-CPB) in group 1 but there was a wide range of reduction produced (3.8-58.8%). The degree of MAC reduction (19.8 +/- 8.6%; P less than 0.05 vs. pre-CPB) produced by CPB in group 2 was much less variable in degree (range 13.0-32.4%) but did not differ from group 1. Although pre- versus post-CPB mean systemic pressure fell from 83 +/- 13 to 69 +/- 15 mmHg (P less than 0.05), this is above the level likely to produce a reduction in MAC. No other significant hemodynamic changes were observed. Temperature pre- versus post-CPB was not different. The degree of hemodilution and acid-base disturbances are unlikely to be the explanation.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Percutaneous-endoscopic placement of endoprostheses for relief of jaundice caused by inoperable bile duct strictures.

Fifty-three patients with biliary obstruction caused by unresectable malignancy were treated by attempted insertion of an endoprosthesis by the percutaneous-endoscopic route. This was successful in 50 patients. A single endoprosthesis was inserted in each case. Both right and left hepatic duct decompression were obtained in 31 patients, but only unilateral or segmental drainage was achieved in 19 patients. Procedure-related complications occurred in 18 (36%) patients, and 15 (30%) patients died within 30 days of the procedure. Satisfactory resolution of jaundice was obtained in 26 (84%) patients with bilateral decompression and in 12 (63%) of those with unilateral drainage. The 30-day mortality rate was 26% for patients with bilateral and 37% for those with unilateral drainage. The morbidity rate from cholangitis after endoprosthesis insertion was 10% after bilateral and 32% after unilateral drainage. None of these differences was statistically significant. Surviving patients with satisfactory bile drainage were relieved of symptoms such as pruritus. The combined percutaneous-endoscopic technique enables difficult biliary strictures to be intubated. Although bilateral duct drainage is preferable, the palliation is often worthwhile even when segmental ducts alone are drained.

Adenoma, Bile Duct↗
PubMed1989

Is lower esophageal contractility a reliable indicator of the adequacy of opioid anesthesia?

Assessing the adequacy of anesthesia in the patient who is without neuromuscular blockade is usually based on somatic as well as sympathetic and hemodynamic responses to stimulation. Because somatic responses are lost in the patient with neuromuscular blockade, a method is needed to replace these signs as an indicator of inadequate anesthesia. This study attempted to determine the relationship between lower esophageal contractility and somatic signs in detecting inadequate fentanyl anesthesia in 20 patients who were undergoing coronary artery surgery and who were hemodynamically stable in the preoperative period. Premedication included midazolam, 0.05 mg/kg intramuscularly, and ranitidine, 2 mg/kg orally. Anesthesia was induced with fentanyl, 50 micrograms/kg, and maintained by an infusion of fentanyl, 0.2 microgram.kg-1.min-1. After endotracheal intubation, a disposable 24-F esophageal monitoring probe equipped with provoking and measuring balloons was inserted, and both the amplitude of provoked and the rate of spontaneous lower esophageal contractions were displayed and recorded. Inadequate anesthesia was indicated by defined somatic signs in response to noxious stimulation. The presence of these responses was correlated with the amplitude of the provoked and the rate of the spontaneous contractions at five specific times during the period preceding initiation of cardiopulmonary bypass. A total of 208 episodes of stimulation were recorded: at insertion of the nasal temperature probe (n = 8), at skin penetration by towel clips (n = 25), at skin incision (n = 20), at sternotomy (n = 20), and during multiple episodes of electrocauterization (n = 135). These provoked 23 somatic responses. The fentanyl concentration in plasma of the 20 patients during the study period was 30 +/- 10 ng/ml (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1989

Gentamicin solution for mediastinal irrigation: systemic absorption, bactericidal activity, and toxicity.

Local irrigation with gentamicin sulfate represents a possible substitute for neomycin sulfate, used for many years but now no longer available for use as an irrigation fluid. In this investigation, mediastinal irrigation with gentamicin was used in 12 patients who had experienced problems after a heart operation. The regimen employed for mediastinal irrigation with gentamicin was equipotent with that using neomycin. We sought to determine the degree of absorption and risk of either inadequate or toxic blood levels that might follow gentamicin absorption. Irrigation periods were short, ranging from one to four days and determined by measurements of plasma gentamicin concentration using radioimmunoassay evaluation. Systemic gentamicin absorption occurred in all patients. Toxic levels of higher than 8.0 micrograms/mL occurred and were size related, ie, correlated with smaller body weight and surface area, and sex related, ie, female sex. Larger-sized patients often had inadequate levels. Despite the potential risk from toxic blood levels, major increases in serum creatinine levels were not seen. These findings suggest that monitoring of plasma gentamicin levels during mediastinal irrigation with gentamicin is mandatory to avoid both inadequate treatment and toxicity.

Absorption↗
PubMed1989

Palliation of obstructive jaundice with a biliary endoprosthesis. Comparison of insertion by the percutaneous-transhepatic and the combined percutaneous-endoscopic routes.

Thirty-eight patients with obstructive jaundice due to inoperable malignancy were referred for insertion of an endoprosthesis. In 19 this was performed by the percutaneous-transhepatic route, and in 19 by a combined percutaneous-endoscopic approach. Satisfactory bile drainage was achieved in 15 patients after combined percutaneous-endoscopic insertion and in 11 after percutaneous-transhepatic prosthesis insertion. Cholangitis occurred after the combined approach in five patients and after percutaneous-transhepatic insertion in nine. None of these differences were significant. Thirty-day mortality rates and mean survival times were similar for each approach (26% and 10 weeks after combined insertion, 21% and 9 weeks after percutaneous-transhepatic). Prostheses inserted by the combined route were easily replaced when they occluded. This was not possible after percutaneous insertion. The combined percutaneous-endoscopic approach appeared to be better tolerated by the patients and is suggested as the method of choice in strictures which can not be intubated by the endoscopic route alone.

Adult↗
PubMed1989

Anesthetic interactions of midazolam and fentanyl: is there acute tolerance to the opioid?

The anesthetic effects and interactions of midazolam and fentanyl were determined in terms of their reduction of enflurane MAC in dogs, and the effects of their specific antagonists were also investigated. Control enflurane MAC was determined by the tail clamp method in 18 mongrel dogs. Each animal then received an iv loading dose of midazolam followed by a constant infusion at 9.6 micrograms.kg-1.min-1 designed to produce a stable enflurane MAC reduction of approximately 40%, and enflurane MAC was determined following a 60-min observation period during which time the midazolam concentration in plasma stabilized. Fentanyl was then administered in a series of three incremental loading doses (15, 30, and 225 micrograms/kg) and infusions (0.05, 0.2, and 3.2 micrograms.kg-1.min-1) designed to produce enflurane MAC reductions of 30%, 50%, and 65%, respectively. Enflurane MAC was again determined following a 60-min observation period for each new infusion. In nine dogs after the fourth determination of enflurane MAC, fentanyl was discontinued and 1 mg/kg naloxone was administered iv every 10 min until enflurane MAC was determined for the last time. In the other nine dogs, midazolam was discontinued and 1.5 mg/kg flumazenil (RO 15-1788) was administered and enflurane MAC determined for the last time. The midazolam concentration in plasma remained stable at 414 +/- 134 ng/ml throughout the study, and in the absence of fentanyl reduced enflurane MAC by 40 +/- 10% (mean +/- SD). The addition of fentanyl produced significant further reductions in enflurane MAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1989

Late results of endoscopic sphincterotomy for bile duct stones in elderly patients with gall bladders in situ.

Endoscopic sphincterotomy was undertaken in 186 patients with common bile duct stones and an intact gall bladder who were considered unfit for surgery. One hundred and seventy one patients had jaundice of whom 18 also had clinical cholangitis. The mean age of treated patients was 79.7 years (range 27-92) and only 13 were aged less than 60. Sphincterotomy was successful in 185 (99%) and complete clearance achieved in 172 (92.5%). Early complications occurred in nine patients (4.8%) of whom three died (1.6%). The patients have been followed on average for 32 months (range six to 72 months). Eighteen patients have subsequently required cholecystectomy (9.6%), with six major complications, but no deaths. There have been 27 natural deaths and 156 patients remain alive and symptom free. Endoscopic treatment alone is safe and effective in the majority of frail and elderly patients and can reduce the need for surgery in this high risk group.

Aged↗
PubMed1989

Epithelial dysplasia in Caroli's disease.

We report a young patient with a solitary intrahepatic cyst without demonstrable connection with the biliary tree. The operative appearances suggested hydatid disease but histological examination of the resected cyst showed that it was the result of Caroli's disease already complicated by severe dysplasia. This case provides further evidence for the premalignant nature of Caroli's disease.

Adult↗