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Biomedical subjects

A J Cunningham

Publications and source records attributed to A J Cunningham.

At least 55 records · Page 3Linked to original sources
PubMed1993

Liquid crystal skin thermometry: an accurate reflection of core temperature?

Oesophageal, rectal, bladder, tympanic and pulmonary artery sites are used intraoperatively to measure body temperature. However, the temperatures measured at each site have different physiological and practical importance. The present two-part study sought to compare liquid crystal (CR) skin temperature with other temperature monitors which are used routinely during surgery. The first part compared CR with oesophageal (OS) temperature during general inhalational anaesthesia. The second part compared CR with OS, pulmonary artery (PA), and bladder (BL) temperatures during the periods of rapid temperature change associated with cardiopulmonary bypass (CPB). During the first part, the mean difference between OS and CR was -0.14 +/- 0.85 degrees C; this difference remained consistent over time (P < 0.05 by repeated measures analysis of variance). During the second part, the difference in temperature readings between CR and each of the other monitors remained consistent except for CR vs PA and CR vs OS during the cooling period of CPB, when the iced cardioplegia slush directly affected the PA and OS temperatures. This study suggests that CR, an inexpensive and noninvasive means of temperature monitoring, reflects trends in temperature changes in the clinical setting.

Anesthesia, Endotracheal↗
PubMed1993

Neuroendocrine and haemodynamic responses to abdominal aortic cross clamp and release during high-dose opiate-oxygen-isoflurane anaesthesia.

The haemodynamic and neuroendocrine responses and beta adrenoceptor distribution associated with aortic cross clamping and release were quantified in 14 patients undergoing elective abdominal aortic aneurysm surgery using a high-dose opiate-oxygen-isoflurane anaesthetic technique. These changes were correlated with neutrophil beta adrenoceptor distribution. Aortic cross clamp application was associated with increased systemic vascular resistance (SVR), and decreased cardiac index (CI). Left ventricular stroke work index remained constant during the period of cross clamp application and following release. Cross clamp release was associated with increased CI and decreased SVR. Plasma cortisol concentrations did not change during the study period. Plasma catecholamine concentrations, although elevated prior to surgery, remained unchanged during aortic cross clamping and following release. The percentage of internalised beta adrenoceptors was elevated before surgery and was unaffected by surgical intervention. This study suggests that a high-dose fentanyl-oxygen-isoflurane anaesthetic technique in a patient population with high circulating catecholamine levels and downregulation of beta adrenoceptors is associated with cardiovascular stability and attenuated neuroendocrine responses.

Aged↗
PubMed1993

Transoesophageal echocardiographic assessment of haemodynamic function during laparoscopic cholecystectomy.

We have measured cardiovascular changes associated with insufflation of carbon dioxide and the reverse Trendelenburg position during laparoscopic cholecystectomy, using transoesophageal echocardiography in 13 healthy patients. End-tidal carbon dioxide values increased after insufflation of carbon dioxide, with values significantly (P < 0.05) increased after lateral tilt positioning. Creation of a pneumoperitoneum was associated with increases (P < 0.05) in left ventricular end-systolic wall stress, concomitant with increases (P < 0.01) in peak airway pressure and systemic arterial pressure. In addition, left ventricular end-diastolic area decreased (P < 0.05) after reverse Trendelenburg positioning. Left ventricular ejection fraction was maintained throughout the study.

Adult↗
PubMed1993

Spinal cord perfusion pressure in dogs after control of proximal aortic hypertension during thoracic aortic cross-clamping with esmolol or sodium nitroprusside.

BACKGROUND: Spinal cord perfusion pressure may be reduced when sodium nitroprusside is used to control proximal aortic hypertension during thoracic aortic clamping. The effect of esmolol infusion on spinal cord perfusion pressure during thoracic aortic clamping is unknown. This study compares spinal cord perfusion pressure following control of proximal hypertension with either sodium nitroprusside or esmolol during thoracic aortic clamping. METHODS: The thoracic aorta was cross-clamped for 30 min in 18 dogs anesthetized with halothane. A control group (n = 6) received no treatment of proximal hypertension during cross-clamping. In two other groups, proximal arterial pressure was controlled (100 mmHg) by infusion of either sodium nitroprusside (n = 6) or esmolol (n = 6). Brachial and femoral arterial pressures, spinal cord perfusion pressure, pulmonary artery occlusion, central venous pressures, and cardiac output were monitored. Neurologic assessment was performed 24 h following surgery. RESULTS: Femoral arterial pressure was lower with nitroprusside (14 +/- 3 mmHg) compared to esmolol (24 +/- 4 mmHg) after 15 min of aortic cross-clamping. Cerebrospinal fluid pressure increased during aortic cross-clamping in the sodium nitroprusside group (from 7 +/- 5 to 16 +/- 6 mmHg) but not in esmolol or control groups. Spinal cord perfusion pressure was lower with nitroprusside at 15 min of aortic cross-clamping (2 +/- 4 mmHg) compared to control (15 +/- 7 mmHg) and esmolol groups (17 +/- 11 mmHg). Esmolol infusion reduced cardiac output and increased ventricular filling pressures compared to control and nitroprusside groups. CONCLUSIONS: Esmolol was associated with greater spinal cord perfusion pressure, but adverse hemodynamic effects, when compared with nitroprusside during thoracic aortic cross-clamping. When only surviving dogs (4 control, 5 esmolol, 6 nitroprusside) are considered, the incidence of neurologic deficit was greater in nitroprusside-treated dogs than in either control or esmolol-treated dogs. No difference in outcome was present when all dogs are considered.

Adrenergic beta-Antagonists↗
PubMed1993

Laparoscopic cholecystectomy: anesthetic implications.

Laparoscopic cholecystectomy is a relatively new surgical procedure, enjoying ever-increasing popularity and presenting new anesthetic challenges. The advantages of shorter hospital stay and more rapid return to normal activities are combined with less pain associated with the small limited incisions and less postoperative ileus compared with the traditional open cholecystectomy. Complications are mostly due to traumatic injuries sustained during blind trocar insertion, and physiologic changes associated with patient positioning and pneumoperitoneum creation. The choice of anesthetic technique for laparoscopic cholecystectomy is limited most frequently to general anesthesia. Controlled ventilation avoids hypercarbia, and an anesthetic technique incorporating antiemetics and nonsteroidal antiinflammatory agents has reduced postoperative nausea and vomiting. The use of nitrous oxide and narcotics during laparoscopic cholecystectomy is controversial. Laparoscopic cholecystectomy is a major advance in the management of patients with symptomatic gallbladder disease. However, in the present era of cost containment, older and sicker patients may present for this procedure on the day of surgery without adequate preoperative evaluation. Anesthesiologists thus should be prepared to recommend conversion to an open procedure if hemodynamic, oxygenation, or ventilation difficulties occur during the procedure.

Anesthesia↗
PubMed1993

Which cancer patients benefit most from a brief, group, coping skills program?

OBJECTIVE: The purpose of this study was to explore the influence of a number of variables on the improvements in quality of life of some 400 cancer patients who completed a brief, group program providing psychosocial support and training in coping skills. METHOD: The factors tested were: patient gender, age, marital status, religion, education level, diagnostic site, recurrence status, expectations of the course, previous experience in self-help techniques, and different group leaders. Three assessment instruments were used, the Profile of Mood States (POMS), the Functional Living Index for Cancer (FLIC), and the Stanford Inventory of Cancer Patient Adjustment (SICPA). Assessments were made at three time points. RESULTS: The overall finding was that the program improved mood and enhanced quality of life for most cancer patients: there was no evidence that it was more or less effective for subgroups based on gender, marital status, religious orientation, education level, and previous experience with mental self-help techniques. It was also found that several different group leaders with widely varying experience facilitated similar improvements. However, there was a significant tendency for patients under fifty to improve more by the end of the program, than older patients, although this difference disappeared at the three month follow-up. In addition, patients with recurrent disease showed less improvement in quality of life than those with primary cancer. CONCLUSIONS: The beneficial effects on quality of life of a seven-session group psychoeducational program were seen across a wide range of categories of cancer patients. The generalizability and implications of these findings are briefly discussed.

Adaptation, Psychological↗
PubMed1992

Transoesophageal pulsed wave Doppler measurement of cardiac output during major vascular surgery: comparison with the thermodilution technique.

We measured cardiac output in 12 patients undergoing elective abdominal vascular surgery at specific times during the procedure with simultaneous thermodilution and transoesophageal pulsed Doppler echocardiographic techniques. No patient had clinical evidence of valvular heart disease before surgery. Five patients had echocardiographic evidence of mitral regurgitation on colour-coded Doppler. Using Bland and Altman analysis to compare the cardiac output measurement by the two techniques, the Doppler method overestimated the cardiac output (bias = 0.86 litre min-1) compared with the thermodilution technique and there were wide limits of agreement between the two techniques (+2.4 to -4.1 litre min-1). However, in the seven patients with no evidence of mitral regurgitation, closer agreement (bias 0.14 litre min-1) and narrower limits (+1.6 to -1.3 litre min-1) were observed. We conclude that, in patients with competent mitral valves, transoesophageal echocardiograph may provide accurate determination of cardiac output.

Aorta↗
PubMed1991

Myocardial contractility and ischaemia in the isolated perfused rat heart with propofol and thiopentone.

The effects of propofol and thiopentone on myocardial contractility and global ischaemia were evaluated using an isolated non-working perfused rat heart preparation. Contractility was assessed using a tension transducer linked to the cardiac apex, and the contractility was expressed as a ratio of the deflection size before and after infusion of the drug. Ischaemia-induced leakage of myocardial proteins and ions (potassium and magnesium) was assessed by comparing the concentrations in the effluent perfusate immediately before and after 60 min of isothermic ischaemia, in the presence of propofol, thiopentone or plain Krebs' buffer solution (control). Mean contractility ratios of 1.15 and 1.3 were obtained with control and propofol groups respectively (NS), but were reduced to 0.5 in the thiopentone group (P less than 0.001). The magnitude of the post-ischaemic leakage of proteins and potassium was similar in each group; however, the post-ischaemic leakage of magnesium was greater in the thiopentone group than in the propofol or control groups. These data suggest that, compared with thiopentone, propofol is not a potent negative inotrope, and that it may cause less disturbance of myocardial magnesium homeostasis during myocardial ischaemia.

Animals↗
PubMed1991

A relationship between perceived self-efficacy and quality of life in cancer patients.

The quality of life of cancer patients may be influenced by the degree of control they feel able to exert over stressful situations arising from having the disease. We were able to test this association using a newly developed instrument, the Stanford Inventory of Cancer Patient Adjustment which assesses perceived self-efficacy, that is, perceived ability to enact coping strategies. In a heterogeneous sample of 273 cancer patients a strong positive correlation was found between self-efficacy and quality of life and between self-efficacy and mood. Improvements in all three measures brought about by a brief, group program teaching coping skills were also highly correlated. By contrast, no significant association was seen between improvement in mood or quality of life and amount of home practice of coping skills.

Adaptation, Psychological↗
PubMed1991

Propofol sedation for outpatient upper gastrointestinal endoscopy: comparison with midazolam.

The objectives of this study were to assess midazolam and propofol as sedative agents for outpatient gastrointestinal endoscopy, with particular reference to recovery profile, amnesic effects, and haemodynamic state and oxygenation during the procedure. Forty consecutive patients were allocated randomly to two groups. Patients in group I (n = 19) received midazolam 81 (SEM 32) micrograms kg-1; those in group II (n = 21) received propofol 950 (400) micrograms kg-1. Both agents were administered as single injections to similar end-points of sedation. Psychomotor function was assessed using the digit symbol substitution test (DSST). Amnesia was measured with a visual memory test and subjective questionnaire. Patients in group I had a lower DSST score than those in group II (P less than 0.01), indicating a hangover effect from midazolam. Amnesia was similar in the two groups up to the time of removal of the endoscope. More patients in group II remembered removal of the endoscope (P less than 0.001). Oxygen desaturation from baseline was similar in both groups (P less than 0.01). An increase in heart rate and decrease in mean arterial pressure were noted in both groups. Propofol provided more rapid recovery compared with midazolam, but was associated with pain on injection, a short amnesia span, and reduced patient acceptance.

Ambulatory Care↗
PubMed1989

The effect of local anaesthetics on epinephrine absorption following rectal mucosal infiltration.

This study was undertaken to investigate the effects of lidocaine and bupivacaine on epinephrine absorption following rectal mucosal infiltration, to assess the cardiovascular and metabolic effects of the absorbed epinephrine and to compare the systemic absorption of the local anaesthetics employed. Three groups of five greyhounds received 1.5 micrograms.kg-1 of epinephrine 1:200,000 in lidocaine 0.5 per cent, bupivacaine 0.5 per cent or 0.9 per cent saline. Plasma epinephrine, lidocaine, bupivacaine, lactate, glucose and potassium concentrations were measured at 1, 2, 5, 10, 15 and 30 minutes following infiltration. Plasma epinephrine concentrations were significantly higher in the lidocaine group at one and two minutes following infiltration. Plasma bupivacaine concentrations were significantly higher than plasma lidocaine concentrations throughout the study period. There were no significant differences in metabolic or biochemical indices within or between the three groups. A local vasodilatory action of lidocaine may enhance epinephrine absorption. Differences in hepatic uptake and rate of metabolism may explain the increased plasma bupivacaine measured. Lidocaine may be the local anaesthetic of choice for ano-rectal procedures, especially when large volumes of local anaesthetic are being infiltrated.

Absorption↗
PubMed1989

Anaesthesia for abdominal aortic surgery--a review (Part II).

Patients presenting for abdominal aortic surgery have a high incidence of vascular disease elsewhere, manifested primarily by hypertension, coronary and cerebrovascular disease, as well as co-existing respiratory, renal and metabolic disorders. Routine clinical assessment, electrocardiogram, chest roentgenograms, resting and exercise radionuclide ventriculography and echocardiography, dipyrdiamole-thallium scanning are all designed to assess the functional status of the myocardium and to detect the presence of significant coronary artery disease. Patients with no abnormalities on physical examination, routine evaluation and no redistribution on dipyridamole-thallium scanning should proceed to surgery with the expectation of very low perioperative cardiac risk. Patients with evidence of coronary artery disease and significant redistribution on dipyridamole-thallium scan should undergo coronary angiography and possible myocardial revascularization before definitive aortic vascular surgery. For high cardiac risk patients with no bypassable lesions presenting for abdominal aortic aneurysm resection a conservative policy of serial three monthly ultrasound or CT assessment may be adopted, with selective resection for rapid aneurysm expansion or symptom development. A variety of extra-anatomical and angioplastic techniques is available for similar high cardiac risk patients with aortoiliac occlusive disease. The haemodynamic consequences of aortic cross-clamping, especially in aneurysm patients, include a significant reduction in stroke volume, cardiac index, and myocardial oxygen consumption with an increased systemic vascular resistance. Patients with coronary artery disease may respond to aortic cross-clamping by increasing pulmonary capillary wedge pressure and by demonstrating ECG evidence of myocardial ischaemia. Pulmonary artery catheterization is especially indicated in patients with a history of previous myocardial infarction, angina or signs of cardiac failure and in patients with evidence of diminished ejection fraction, abnormal ventricular wall motion or myocardial redistribution on preoperative scanning. The more widespread application of intraoperative transoesophageal two-dimensional echocardiography and radionuclide cardiography monitoring techniques into anaesthetic practice will enable measurement of left ventricular dimensions, myocardial performance and wall motion. Suggested guidelines for anaesthetic management are presented in Table VI. A combined opiate-oxygen-volatile anaesthetic agent technique will best ensure a hypodynamic circulation with preservation of myocardial oxygenation.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗