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Biomedical subjects

A R Aitkenhead

Publications and source records attributed to A R Aitkenhead.

70 records · Page 4Linked to original sources
PubMed1984

Anaesthesia and bowel surgery.

Many factors influence the outcome after surgery of the bowel. However, care in anaesthetic and postoperative management may help to reduce the frequency of complications. Such care can be directed at maintenance of or improvement in oxygen delivery to the bowel by the avoidance of hypoxia, hypocapnia and hypovolaemia, and by careful selection of drugs and techniques used during anaesthesia. Tension on anastomoses can be reduced by care in the administration of neostigmine, and possibly by the use of pethidine rather than morphine for analgesia during and after operation. Postoperative ileus may be affected by sedative and analgesic therapy.

Analgesics, Opioid↗
PubMed1984

Pharmacokinetics of single-dose i.v. morphine in normal volunteers and patients with end-stage renal failure.

Morphine 0.125 mg kg-1 was administered i.v. to 11 normal subjects and nine patients with chronic renal failure requiring regular haemodialysis. Plasma morphine concentrations were measured using high pressure liquid chromatography (HPLC). Although there was considerable individual variation in both groups, mean plasma concentrations of morphine were significantly higher in the patients with renal failure for 15 min after administration. The decay of plasma concentration fitted a three-compartment mamillary pharmacokinetic model in all subjects. Derived values (mean +/- SEM) of T 1/2 alpha, volume of distribution of the second compartment (V2), total volume of distribution at steady state (Vss) and transfer rate constant from the first to the second compartment (k12), were significantly different between groups. Mean values of terminal elimination half-life (T 1/2 gamma) and total body clearance were similar in the two groups. It was concluded that elimination of unchanged morphine is not impaired significantly in patients with chronic renal failure, although accumulation of morphine-3-glucuronide probably occurs. Although the pharmacological effect of morphine is not related temporally to plasma morphine concentrations, the higher values in patients with renal failure may be implicated in their increased sensitivity to the drug.

Adult↗
PubMed1984

Pharmacokinetics and analgesic effect of slow-release oral morphine sulphate in volunteers.

Sustained-release oral morphine sulphate (MST) 20 mg was administered to 11 healthy volunteers. Mean peak plasma morphine concentration was 14.8 ng ml-1, and occurred at a mean time of 142.5 min after ingestion. Analgesia assessed by an ischaemic forearm pain test increased to a maximum approximately 40 min after the calculated peak plasma concentration of morphine had been achieved, and remained greater than control values as plasma morphine concentration decayed. However, there was not a significant correlation between analgesia and plasma morphine concentration. This may result from delay in brain penetration by morphine. The mean systemic availability of morphine in the first 7 h after administration of MST was 18.3%.

Administration, Oral↗
PubMed1984

Non-parenteral postoperative analgesia. A comparison of sublingual buprenorphine and morphine sulphate (slow release) tablets.

Sixty-nine patients undergoing upper and lower abdominal surgery were studied after operation to compare the analgesic effects of sublingual buprenorphine (0.4 mg) and slow release morphine sulphate tablets (MST, 20 mg) given 6 hourly in a double-blind, double-dummy trial. Both MST and buprenorphine produced satisfactory postoperative analgesia but the linear analogue pain scores were significantly lower on the second post operative day with MST.

Abdomen↗
PubMed1984

Anaesthesia for bowel surgery.

The most important complications following gastrointestinal surgery are related to disruption of anastomoses. The fate of a gastrointestinal anastomosis is influenced by many factors. Among these, care in the anaesthetic management and postoperative treatment may reduce the incidence of complications. There are two major directions in which such care may be aimed. The prevention of high intra-luminal pressures and excessive longitudinal traction across anastomoses may be aided by care in the administration of neostigmine, and possibly by the avoidance of morphine for provision of intra-operative and postoperative analgesia. Maintenance of, or improvements in, oxygen supply to an anastomosis may be achieved by avoiding hypoxia, hypocapnia and hypovolaemia, and by the use of regional anaesthetic techniques during surgery and/or in the post-operative period. In addition, sedative and analgesic therapy may influence the incidence of postoperative ileus, and may thus contribute to morbidity.

Analgesia↗
PubMed1983

Quantitative effects of respired helium and oxygen mixtures on gas flow using conventional oxygen masks.

A model lung system with a variable artificial constriction was used to quantify the changes in flow produced by the addition of helium to the gas mixture in the system. The tracheal concentration of helium obtained when administering 79% helium/21% oxygen to the system via conventional, disposable face masks was determined using a resuscitation dummy. The greatest proportion of the increase in flow through the orifice occurred at concentrations of helium up to 40%. A tracheal concentration of 40% helium could be obtained with all oxygen masks at fresh gas flow rates greater than 8 litres/minute. These findings will help to rationalise the administration of 79% helium/21% oxygen to patients with upper respiratory tract obstruction.

Airway Obstruction↗
PubMed1983

Awareness during anaesthesia: a review.

Following the introduction of muscle relaxants into anaesthesia there became recognised a state in which patients may be aware of their surroundings but unable to communicate their plight. This state of awareness is more likely to occur during light inhalational or total intravenous anaesthesia. Detection of awareness is difficult and several methods have been described. Measurement of the depth of anaesthesia is also difficult as clinical signs are unreliable and even sophisticated monitoring equipment is unhelpful. Awareness can occur without patient recall and may be due to equipment failure or anaesthetic failure. The former is avoidable and the latter ought to be. Recommendations have been made regarding the use of premedicant drugs and volatile anaesthetic agents to reduce the incidence of awareness.

Anesthesia, General↗
PubMed1980

An economical mobile intensive care unit.

A mobile intensive care unit is an important extension of a regional intensive treatment service. The treatment and monitoring of critically ill patients can be maintained during transfer for specialist investigation or treatment. Such units can be brought into service with low construction and running costs.

Ambulances↗
PubMed1980

The effect of hypovolaemia on colonic blood flow in the dog.

The effects of a minor degree of hypovolaemia on colonic blood flow and on systemic haemodynamics have been studied in nine greyhound dogs. A loss in blood volume of 10 per cent over 20 min produced no change in blood pressure and only a 7 per cent rise in heart rate. Cardiac output, however, fell by 26 per cent and central venous pressure also fell significantly. Colonic blood flow fell by 28 per cent and oxygen availability by 29 per cent. All these changes were statistically highly significant. Retransfusion of shed blood resulted in a slow and incomplete return to pre-bleed status. Since colonic blood flow and oxygen availability during and after surgery may be important for colonic healing, it is suggested that even the slightest degree of hypovolaemia should be avoided in cases involving colonic anastomosis. Systemic blood pressure may be an inadequate index of the need for transfusion in these cases.

Animals↗
PubMed1980

Colon blood flow in the dog: effects of changes in arterial carbon dioxide tension.

A new method for measuring blood flow in the colon using a 133Xenon clearance technique has been developed in the greyhound. Values for 133Xe tissue blood partition coefficient for colon have been established. The mean basal colon blood flow in 35 animals was 39.8 cm3.min-1.100g-1 with a coefficient of variation for repeat measurements of 8.7%. Hypercapnia produced a significant rise in colon blood flow to a mean maximum level of 62.2 cm3.min-1.100g-1 and hypocapnia a significant fall to a mean level of 27.9 cm3.min-1.100g-1. For arterial carbon dioxide tension (PCO2) values between 2 and 12 kPa (15 and 90 mmHg) there was a straight line relationship between colon blood flow and arterial PCO2. When hypercapnia was prolonged for 75 min, the initial rise in colon blood flow was only partially sustained, while prolonged hypocapnia for a similar period resulted in sustained reduction in flow. Mean resting colon oxygen consumption in 35 animals was 1.17 cm3.min-1.100g-1 and this was not significantly affected by hypocapnia. Hypercapnia to arterial PCO2 levels between 8 and 14 kPa (60 and 105 mmHg), however, produced a significant rise in colon oxygen consumption. Since changes in colon blood flow during and after surgery may affect healing of colonic anastomoses, these results may be relevant when considering anaesthetic techniques for patients undergoing colon resection.

Animals↗
PubMed1979

Dural dimpling in the dog.

Indentation of the dura has been proposed as the cause of subatmospheric pressure in the extradural space, but has never been demonstrated directly in humans. In this study, radiographs have been produced showing dimpling of the dura by a needle tip lying in the extradural space in the dog. Pressure tracings demonstrate that advancement of the needle tip produces a progressive decrease in extradural pressure, and observations made using an image intensifier have confirmed that the pressure changes are proportional to the degree of dural indentation.

Anesthesia, Epidural↗
PubMed1978

Movement of the critically ill within hospital.

Critically ill patients can be safely moved within hospital using a mobile intensive care unit (MICU). The MICU allows the critically ill to benefit from specialised investigation and treatment they might otherwise be denied. The MICU in use at the Western Infirmary, Glasgow is described and its merits outline in the light of clinical experience gained over a twelve month period.

Adult↗
PubMed1978

High spinal nerve block for large bowel anastomosis. A retrospective study.

In a retrospective study, 68 large bowel anastomoses carried out on patients under subarachnoid or extradural spinal nerve block with light general anaesthesia were compared with 26 anastomoses on patients receiving general anaesthesia alone. Dehiscence occurred in 7.4% of anastomoses performed under spinal nerve block compared with 23.1% in the control group. In patients receiving morphine, anastomotic dehiscence occurred after 15.2% of operations, compared with 5.9% in patients receiving pethidine. These differences are not statistically significant. However, the findings indicate the need for larger prospective studies.

Anesthesia, General↗