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Biomedical subjects

R I Hall

Publications and source records attributed to R I Hall.

At least 73 records · Page 4Linked to original sources
PubMed1989

Comparison of the effects of enteral feeding with continuous and intermittent parenteral nutrition on hepatic triglyceride secretion in human beings.

Plasma triglyceride turnover was measured during steady-state conditions in 22 postoperative patients. Nine had received nutritional support with an enteral regimen, seven had received an equivalent regimen as continuous parenteral nutrition, and six received the same parenteral regimen as a cyclical infusion. After 5 days of nutritional support, each patient received an intravenous bolus of tritiated glycerol. Plasma radiolabeled triglyceride content was measured during the subsequent 24 hours. The data were analyzed by means of a simple deterministic model of plasma triglyceride kinetics and compared with the results obtained by stochastic analysis. The rates of hepatic triglyceride secretion obtained by deterministic analysis were higher than those obtained by the stochastic approach. However, the mode of delivery of the nutritional regimen did not affect the rate of hepatic triglyceride secretion regardless of the method of analysis. The results suggest that neither complete nutritional bypass of the gastrointestinal tract nor interruption of parenteral nutrition in an attempt to mimic normal eating has any effect on hepatic triglyceride secretion. Any beneficial effect that enteral feeding or cyclical parenteral nutrition may have on liver dysfunction associated with standard parenteral nutrition appears to be unrelated to changes in hepatic triglyceride secretion.

Aged↗
PubMed1988

Pharmacokinetics and pharmacodynamics of midazolam in the enflurane-anesthetized dog.

Midazolam (Mid) is widely used as an anesthetic adjunct. To test its anesthetic effect vs. concentration relationships, it is desirable to establish stable and predictable Mid concentrations in plasma (and brain). Therefore, the pharmacokinetics of Mid in the enflurane-anesthetized dog were determined, and the ability of Mid to reduce the enflurane concentration required for anesthesia was measured and correlated with the Mid concentration in plasma [MID]. Mongrel dogs (n = 9) were anesthetized with enflurane and the enflurane EC50 (MAC--the end-tidal concentration at which one-half of the dogs respond to the noxious stimulation of clamping of the tail, and one-half do not) was determined. Group 1 (n = 5) received Mid 2.5 mg/kg iv over 60 sec. Plasma for determination of [MID] was collected and the enflurane EC50 was determined repeatedly over the 7-8-hr period following injection. Based on the pharmacokinetic parameters determined for Group 1, dogs in Group 2 (n = 4) received Mid as a continuous infusion of 21 micrograms kg-1 min-1 for 5 hr accompanied by an initial loading dose (3 mg/kg infused over 20 min) designed to produce a stable [MID] of 1000 ng/ml in plasma. Enflurane MAC and [MID] were determined regularly during the infusion and for 6 hr after discontinuation of the infusion. There were no important differences in the pharmacokinetic parameters determined for Group 1 vs. Group 2: t1/2,z = 98 +/- 5 vs. 95 +/- 10 min (mean +/- SEM); V = 3.94 +/- 0.27 vs. 2.98 +/- 25 L/kg; Cl = 28.5 +/- 3.1 vs. 22.3 +/- 1.1 ml kg-1 min-1, respectively. When administered as a continuous intravenous infusion (Group 2), [MID] remained stable at 949 +/- 53 ng/ml for more than 5 hr. The enflurane EC50 was reduced by 55% and the reduction remained stable during the 5 hours of Mid infusion. After a single iv bolus dose or after discontinuation of the continuous infusion, the degree of enflurane EC50 reduction diminished toward the control (i.e., enflurane alone) value as [MID] declined. Mid-azolam's pharmacokinetics and plasma concentration vs. effect relationships have been determined to be consistent under two different experimental conditions.

Anesthesia, General↗
PubMed1988

The value of a barium enema in the investigation of patients with rectal carcinoma.

A review of 545 patients with clinically diagnosed rectal carcinoma was conducted to determine the diagnostic usefulness of pre-operative barium enema and the frequency with which it was employed. Only 118 patients underwent pre-operative barium enema (21.7%). This successfully outlined the whole colon in 107 (90%). Synchronous carcinomas were detected in 9.3% of patients who underwent complete barium enema, compared to 4.3% of those who underwent laparotomy alone (P less than 0.05). Polyps were found in 23.4% of patients who had a barium enema but in only 14.7% of those who did not (P less than 0.05). Twenty-nine per cent of synchronous carcinomas and 11% of polyps were proximal to the descending colon and would have been beyond the reach of a flexible sigmoidoscope. Barium enema remains a useful investigation in patients with rectal carcinoma. It will outline the whole colon in most cases and will result in the detection of more synchronous carcinomas and polyps than if the surgeon relies on operative palpation alone.

Barium Sulfate↗
PubMed1988

Alfentanil plasma concentration v. effect relationships in cardiac surgical patients.

Effects of alfentanil, preceded by lorazepam, on suppression of haemodynamic and somatic responses to noxious stimuli was studied in patients undergoing CABG. Plasma concentration of alfentanil, somatic and haemodynamic responses were measured at loss of consciousness, tracheal intubation, sternotomy and during multiple application of electrocoagulation. Additional alfentanil was administered i.v. to control unwanted responses. Study 1 (six patients): lorazepam 0.08 mg kg-1 by mouth 1-2 h before operation, alfentanil priming infusion (60 micrograms kg-1 min-1 for 10 min) followed by maintenance infusion (4.5 micrograms kg-1 min-1). With mean plasma alfentanil 1178 (SEM 54) ng ml-1, two patients required supplementary alfentanil to suppress somatic motor responses; one patients required nitroglycerin to control an increase in arterial pressure which was unresponsive to additional alfentanil following sternotomy. Study 2 (13 patients): lorazepam 0.04 mg kg-1 by mouth as premedication; one of three maintenance infusion rates of alfentanil: 5.4 (n = 4), 6.6 (n = 5), or 7.8 (n = 4) micrograms kg-1 min-1, each preceded by a proportional priming infusion. With plasma alfentanil 2181 (62) ng ml-1, somatic motor responses requiring additional alfentanil occurred in nine patients; haemodynamic responses in four of seven patients tested could not be controlled by alfentanil. The highest plasma concentration of alfentanil to prevent response to a stimulus other than tracheal intubation was different between the two studies (P less than 0.05). We conclude that alfentanil alone is insufficient to suppress haemodynamic and somatic motor responses to noxious stimulation during CABG and that the role of premedication is significant.

Alfentanil↗
PubMed1988

The anesthetic efficacy of midazolam in the enflurane-anesthetized dog.

This study determined the anesthetic efficacy of midazolam (MID) in terms of its ability to reduce enflurane MAC (EMAC). Control EMAC was determined by the tail-clamp method in 15 mongrel dogs. Each animal then received at least three incremental infusion rates of MID from among the following: 0.48, 2.4, 9.6, 19.2, 28.8, 48, or 151.2 micrograms.kg-1.min-1. MAC was determined during each infusion rate following a 1-h observation period, during which time MID concentration in plasma [( MID]) stabilized. [MID] was measured every 15 min beginning 45 min from the start of each new infusion rate. There was a linear relationship between MID infusion rates and the resulting [MID] (r = 0.995). In the range of [MID] from 14 to 14,118 ng/ml, there was a linear relationship between the log [MID] and the percent EMAC reduction. The slope of the line was very shallow, and the [MID] required to reduce EMAC by more than 50% exceeded the [MID] likely to be employed clinically in humans (750 ng/ml). Also, the 73 +/- 4% (mean +/- SEM) EMAC reduction produced by [MID] = 9,763 +/- 1213 ng/ml was not significantly greater than the 60 +/- 3% EMAC reduction achieved by [MID] = 1,464 +/- 293 ng/ml, a finding which suggests a ceiling effect to the anesthetic efficacy of midazolam. The authors conclude that, within the dose range of MID likely to be employed in humans, MID produced a concentration-dependent reduction of enflurane MAC in the dog. In doses above those likely to be employed clinically, a ceiling effect to the anesthetic efficacy of MID may become evident.

Adjuvants, Anesthesia↗
PubMed1987

The enflurane sparing effect of sufentanil in dogs.

There is a ceiling to the reduction of enflurane MAC by fentanyl in the dog. Sufentanil (SUF), a more potent narcotic, may be more efficacious in reducing enflurane MAC. To test this hypothesis, 25 mongrel dogs were studied in three groups. Group 1 (n = 8) received SUF in progressively increasing infusion rates from 0.005 micrograms . kg-1 . min-1 to a maximum of 1.215 micrograms . kg-1 . min-1. MAC was determined at stable SUF concentrations in plasma [SUF] during each infusion rate. Group 2 (n = 10) received SUF at a dose rate (0.007 micrograms . kg-1 . min-1) designed to produce approximately 35% MAC reduction, and MAC determinations were made at regular intervals over a mean infusion time of 7.6 +/- 0.43 h (mean +/- SEM). Group 3 (n = 7) received 1.215 micrograms . kg-1 . min-1 and were studied as in group 2 over an infusion time of 6.7 +/- 0.42 h. In group 1, the highest infusion rate (1.215 micrograms . kg-1 . min-1) produced [SUF] = 48 ng/ml and reduced MAC by 71 +/- 6%. This was not statistically different from the reduction which occurred at [SUF] = 0.92 ng/ml (57 +/- 7%; infusion rate 0.015 micrograms . kg-1 . min-1; P = 0.21). In group 2, the degree of MAC reduction achieved by stable [SUF] (0.54 +/- 0.08 ng/ml) declined over time (MAC reduction at start = 34 +/- 2% versus 18 +/- 4.0% at the end of the infusion; P = 0.001), suggesting the development of tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Endoscopic needle aspiration cytology: a new method for the diagnosis of upper gastrointestinal cancer.

A technique for obtaining needle aspiration cytology specimens from upper gastrointestinal lesions at endoscopy is described. The validity of the technique was initially confirmed by applying it to resected gastric carcinomas. Thirty seven endoscopically visualised lesions were then sampled by forceps biopsy, brush and needle cytology. Ten lesions were subsequently found to be carcinomas. Needle aspiration produced identifiable malignant cells from seven of these lesions. In two it was the only sampling method which provided the correct diagnosis. This technique may be a useful addition to conventional endoscopic sampling methods, particularly where tumours lie deep to normal mucosa, or necrotic slough.

Biopsy, Needle↗
PubMed1987

The enflurane-sparing effect of alfentanil in dogs.

Some investigators believe that the dog is less sensitive than are humans to the anesthetic/analgesic actions of opioids. The alfentanil plasma concentration [ALF] vs anesthetic effect relationship has been determined for humans undergoing surgery. This study was designed to determine the [ALF] vs anesthetic relationship for alfentanil in the enflurane-anesthetized dog and thereby to provide data by which the [ALF] vs anesthetic effect relationships in the dog and in humans could be compared. Mongrel dogs (n = 10) were anesthetized with enflurane, and enflurane MAC (EMAC) was determined in each dog. After this, each dog received at least three incremental infusions of alfentanil using infusion rates of 0.625, 1.6, 8, 32, or 80 micrograms.kg-1.min-1. EMAC and [ALF] were determined during each infusion rate. There was a linear increase in [ALF] produced by incremental infusions of alfentanil (r = 0.999). Administration of alfentanil produced a dose-dependent reduction of EMAC up to a maximum of 72.5 +/- 3.7% (mean +/- SEM) at 32 micrograms.kg-1.min-1 ([ALF] = 960 +/- 86 ng/ml); a ceiling effect was evident. The degree of EMAC reduction (69%) produced by an infusion rate of 8 micrograms.kg-1.min-1 ([ALF] = 223 +/- 13 ng/ml) was not statistically different from the EMAC reductions produced by infusion rates of 32 (73% reduction at [ALF] = 960 +/- 86 ng/ml) or 80 micrograms.kg-1.min-1 (70% reduction at [ALF] = 2613 +/- 247 ng/ml) (P greater than 0.05). The relative potency of alfentanil was one-seventh to one-tenth that of fentanyl studied under identical conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Anesthesia↗
PubMed1987

Dezocine-MAC reduction and evidence for myocardial depression in the presence of enflurane.

The effect of dezocine, an agonist-antagonist opioid analgesic, on enflurane MAC (EMAC) was measured in dogs and, in a separate study, the hemodynamic effects of IV bolus doses of dezocine in the presence of a stable end-tidal enflurane concentration were measured. Study 1 (n = 8)--EMAC Reduction: Dezocine reduced EMAC in a dose-dependent fashion by a maximum of 58 +/- 3% (mean +/- SEM) after injection of 20 mg/kg. Cardiac toxicity prevented administration of higher doses. Study 2--Hemodynamics: Group 1 (n = 7) received dezocine 0.2, 1.5, 5, and 20 mg/kg IV each as a bolus over 30 sec. Group 2 (n = 5) was studied in exactly the same manner except that instead of dezocine, each dog received drug carrier solution alone (carrier). Significant hemodynamic differences between carrier and drug groups were observed only at the 20 mg/kg dose level, which produced death in one dog and a decrease in mean aortic pressure to 39 +/- 5% of baseline, in cardiac output to 60 +/- 9% of baseline, and in stroke volume to 69 +/- 9% of baseline in the remaining dogs. It is concluded that dezocine produces a dose-dependent reduction in EMAC limited by cardiovascular toxicity. This toxicity appears to be related to direct myocardial depression by high doses of dezocine in the presence of enflurane.

Analgesics↗
PubMed1986

Use of ERCP to identify the site of traumatic injuries of the main pancreatic duct in children.

Major pancreatic injuries in children are uncommon but potentially very serious. They usually occur in active young boys following characteristic accidents. Despite this they frequently go unrecognized for prolonged periods. Four patients with delayed recognition of blunt pancreatic trauma are described. The presence of pancreatic injury was identified by hyperamylasaemia in every case. Ultrasound and CT scanning were helpful in identifying pseudocysts but accurate pre-operative diagnosis of main duct disruption required endoscopic retrograde cholangiopancreatography (ERCP). Surgical treatment involved a full exploration of the lesser sac with drainage of the cyst contents and identification of the site of extravasation. Two patients with proximal duct lacerations were treated by internal drainage into a Roux-en-Y loop with the addition of a distal pancreaticojejunostomy in one case. Two patients with distal lacerations were treated by distal pancreatectomy and oversewing of the remnant. All four patients recovered and were well at follow-up. Early ERCP is the only reliable method of identifying duct injuries which require urgent surgery. It should be considered in all children with blunt pancreatic trauma.

Adolescent↗
PubMed1985

Cystic adventitial disease of the common femoral and popliteal arteries.

Cystic adventitial arterial disease (CAAD) is usually situated in the popliteal artery and is a well recognized cause of intermittent claudication in otherwise healthy, young, non-smokers. Three cases of CAAD have recently been encountered, involving the popliteal artery in two patients and the common femoral in one. Two of these patients were hypertensive smokers in their sixth decades and only one was an otherwise healthy non-smoker, but all three had a characteristically rapid onset of symptoms. All had angiographic appearances suggestive of CAAD, confirmed by ultrasound and CAT scanning in one patient. Two were treated by resection of the affected artery and a replacement graft, both with excellent results. One popliteal lesion was bypassed with a vein graft which occluded after 3 months. CAAD may occur more commonly than generally realized. It can present in patients whose condition suggests an atheromatous cause for their symptoms. Since good results can be expected from appropriate surgical treatment in most cases, CAAD should be considered in the diagnosis of all patients with claudication, particularly when the onset has been rapid.

Arterial Occlusive Diseases↗
PubMed1985

A prospective trial of prophylactic povidone iodine in lacerations of the hand.

A series of 418 patients with lacerations of the hands were allocated randomly to a control group or to a group where the injury was treated with povidone iodine before suture. The incidence of infected and imperfectly healed wounds was determined seven days later. As well as the effect of povidone iodine on infection, thirteen other factors were also analysed. The overall infection rate of 5.0% and the 38.5% imperfect healing rate were not significantly affected by povidone iodine treatment, although both were reduced. The figures of four other trials were combined with this trial and this showed a significant effect of povidone iodine treatment. There were no adverse reactions to povidone iodine. It is therefore recommended that hand lacerations should be treated with povidone iodine prior to suture. Other factors found to be significantly important in wound infection or imperfect healing were the condition of the dressing, the part of the hand injured and pain. Patients should be strongly advised to keep their dressing clean and dry.

Adolescent↗
PubMed1984

Pathogenesis of hepatic steatosis in the parenterally fed rat.

Hepatic steatosis frequently complicates total parenteral nutrition (TPN). Some of the mechanisms responsible were examined in rats receiving calories as dextrose (CHO-TPN) or dextrose plus lipid emulsion (Lipid-TPN). Hepatic triglyceride content increased approximately threefold after CHO-TPN and twofold after Lipid-TPN (P less than 0.02). Hepatic triglyceride fatty acid composition reflected endogenous synthesis. Hepatic acetyl-Coenzyme A carboxylase specific activity increased fourfold after CHO-TPN and twofold after Lipid-TPN, and it correlated positively with hepatic lipid content (r = 0.82). The activities of the microsomal enzymes of complex lipid synthesis were unchanged in the TPN groups. Both TPN regimens suppressed hepatic triglyceride secretion, measured by the rise in plasma triglyceride and the incorporation of [14C]palmitic acid into plasma triglyceride after intravenous Triton. Hepatic triglyceride secretion correlated negatively with total hepatic lipid content (r = -0.89). CHO-TPN increased the uptake of a radiolabeled triglyceride emulsion and increased hepatic lipase activity, whereas Lipid-TPN decreased both. Both adipose and cardiac lipase were higher for Lipid-TPN animals than for CHO-TPN or control animals. Hepatic 14C-triglyceride content was increased in both TPN groups as compared with controls after the injection of 1-[14C]-palmitic acid. This increment was proportional to the decreased hepatic secretion. Triglyceride fatty acid oxidation was significantly suppressed by CHO-TPN, less so by Lipid-TPN. Free fatty acid oxidation was suppressed only by CHO-TPN. The results suggest that the steatosis induced by TPN in rats was due to enhanced hepatic synthesis of fatty acid and reduced triglyceride secretion. Reduced hepatic triglyceride uptake, enhanced fatty acid oxidation, and enhanced peripheral tissue plasma triglyceride lipolysis when CHO-TPN is supplemented with lipid may modulate the accumulation of hepatic triglyceride and, along with reduced synthesis of fatty acid, lead to a lower hepatic triglyceride content.

Animals↗