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Biomedical subjects

A J Cunningham

Publications and source records attributed to A J Cunningham.

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

The influence of collateral vascularisation on haemodynamic performance during abdominal aortic surgery.

The extent of periaortic collateral vascularisation has been proposed as a possible mechanism of an altered haemodynamic response to infra-renal aortic cross-clamp in patients undergoing by-pass grafting for aorto-iliac occlusive disease (AOD) compared with patients undergoing abdominal aortic aneurysm (AAA) resection. The haemodynamic responses following clamping, during the clamp time and following clamp release were studied in 18 patients undergoing AAA resection and 12 patients undergoing bypass grafting for AOD. The role of preoperative aortography in predicting cardiovascular performance during aortic vascular surgery was assessed. During the cross-clamp period LVSWI and CI decreased while SVR increased in the AAA group while the AOD group showed an improved CI, stable LVSWI and reduced SVR, which correlated with the extent of periaortic vascularisation on preoperative aortography. Chronic collateral circulation associated with AOD may permit continuous lower extremity perfusion during aortic cross-clamp. The extent of periaortic collateralisation may influence the choice of monitoring techniques and anaesthetic management.

Aged↗
PubMed1989

Interscalene brachial plexus blockade with lidocaine in chronic renal failure--a pharmacokinetic study.

Plasma lidocaine concentrations, latency of onset, and duration of anaesthesia, were determined after interscalene brachial plexus block in 16 patients presenting for elective upper limb surgery. Eight patients had normal renal function and eight had chronic renal failure, as determined by creatinine clearance. Significantly higher plasma lidocaine levels were recorded ten minutes after infiltration in patients with chronic renal failure (p less than 0.05). Cmax plasma levels for normal patients (5.6 +/- 1.1 micrograms.ml-1) and for patients with chronic renal failure (6.6 +/- 1.6 micrograms.ml-1) were not significantly different. The latency of onset and duration of anaesthesia were similar in both groups. One per cent lidocaine solution may be administered to patients with normal and impaired renal function to provide effective brachial plexus blockade for short surgical procedures.

Adult↗
PubMed1989

Intraoperative cerebral ischaemia.

The brain is highly vulnerable to damage from even a brief imbalance of oxygen delivery and demand. Most cerebral hypoxic damage is reversible, but infarction and permanent brain damage may result.

Brain Ischemia↗
PubMed1988

Radionuclide ventriculography and two dimensional echocardiography as predictors of left ventricular performance during aortic vascular surgery.

Sixteen consecutive patients scheduled for elective aortic vascular surgery underwent preoperative LVEF determination employing two dimensional echocardiography (2DE) and radionuclide ventriculography (RNV). Measured and derived indices of cardiac function were recorded before and after induction of anaesthesia, aortic cross-clamping and aortic unclamping. Induction of anaesthesia was associated with significant decreases in mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and with a highly significant decrease in left ventricular stroke work index (LVSWI). Aortic cross-clamping was associated with significant increases in MAP and systemic vascular resistance (SVR) whereas aortic unclamping was associated with a significant decrease in SVR. Preoperative LVEF, as measured by RNV and 2DE, were similar. Resting ejection fractions correlated poorly with both preoperative cardiac indices and with changes in indices of left ventricular performance seen intraoperatively. Preoperative ejection fraction determination did not predict intraoperative left ventricular performance. Preoperative exercise scanning may prove more informative.

Aged↗
PubMed1988

Phaeochromocytoma--a presentation mimicking malignant hyperthermia.

A 52-year-old apparently healthy, normotensive woman who presented for elective cholecystectomy experienced intra-operative hypertension and tachycardia, which were controlled by propranolol. Oesophageal temperature increased, there was a metabolic and respiratory acidosis with hypoxaemia, and malignant hyperthermia was diagnosed. Severe cardiogenic pulmonary oedema ensued, and was treated with intravenous glyceryl trinitrate. Ventricular fibrillation caused cardiac arrest, and this was treated successfully. Postoperatively a phaeochromocytoma was discovered, and removed at a subsequent operation. The case illustrates the similarities in presentation of malignant hyperthermia and phaeochromocytoma, and the possibility that misdiagnosis may exacerbate the crisis.

Adrenal Gland Neoplasms↗
PubMed1986

Intraocular pressure--physiology and implications for anaesthetic management.

The major factors controlling intraocular pressure during surgery are the dynamic balance between aqueous humour production in the ciliary body and its elimination via the canal of Schlemm; the auto-regulation and chemical control of choridal blood volume; the extraocular muscle tone and vitreous humour volume. Prior to surgical incision of the anterior chamber in open intraocular procedures, a low-normal intraocular pressure is mandatory to avoid the hazards of iris or lens prolapse and vitreous loss associated with sudden decompression. In general, the central nervous system depressant drugs, hypnotics, narcotics, major tranquillizers, volatile anaesthetic agents are associated with a reduction in intraocular pressure, with the exception of ketamine and possibly trichloroethylene. The mechanism of action of anaesthetic agents in reducing intraocular pressure may involve a direct effect on central diencephalic control centres, reduction of aqueous production, facilitation of aqueous drainage or relaxation of extraocular muscle tone. Succinylcholine administration is associated with a significant rise in intraocular pressure, with a peak increase between two to four minutes following administration and a return to base line values after six minutes. The intraocular hypertensive effect may be due to a tonic contraction of the extraocular muscles, choroidal vascular dilatation or relaxation of orbital smooth muscle. Despite many claims to the contrary, no reported method to date has been shown to consistently prevent the intraocular hypertensive response to intravenous succinylcholine administration. Because the non-depolarizing relaxants are associated with a reduced intraocular pressure, a barbiturate-non-depolarizing relaxant technique utilizing preoxygenation and cricoid pressure has evolved as the most commonly employed induction technique for the emergency repair of a penetrating eye injury. The alternative non-depolarizing relaxant pretreatment-barbiturate-succinylcholine technique may offer the advantages of more rapid onset of relaxation with only minor increases in intraocular pressure and in a carefully controlled rapid sequence induction technique may be the most acceptable method of handling emergency penetrating eye injuries.

Anesthesia↗
PubMed1986

Aspiration pneumonia and coma--an unusual presentation of dystrophic myotonia.

A 30-year-old female patient presented in a comatose state with clinical and radiographic signs of aspiration pneumonia 16 hours following elective surgery. Subsequent clinical assessment and investigations revealed the characteristic facies, proximal muscle weakness, lenticular opacities, pulmonary function defects, arterial desaturation and abnormal breathing during rapid eye movement (REM) sleep often associated with myotonia dystrophica. Although these characteristic features were evident on clinical examination postoperatively they were not noted in the preoperative assessment. The aspiration pneumonia and coma were unusual presenting features of this disease. Unsuspected myotonia dystrophica should be considered in the differential diagnosis of unexplained respiratory depression, aspiration or comatose state following surgery. Recognition of the disorder during the preoperative assessment is the key to avoiding complications during the perioperative management of such patients.

Adult↗
PubMed1985

Cardiovascular and metabolic effects of cervical epinephrine infiltration.

Ventricular arrhythmia may follow the infiltration of dilute, epinephrine-containing solutions to achieve hemostasis during surgery. The objective of this study was to determine the cardiovascular and metabolic changes associated with the infiltration of 1.5 micrograms/kg epinephrine 1:200,000 in 0.5% lidocaine into the cervix of patients having a cervical cone biopsy under epidural anesthesia. These observations were compared with a control group who were infiltrated with 0.5% plain lidocaine under similar epidural anesthesia during cone biopsy. In the epinephrine-treated group, marked heart rate, rhythm, and systolic/diastolic blood pressure changes from baseline values were observed as well as significant glycogenolysis, lactic acidosis, and hypokalemia. Based on these observations, the total dose of injected epinephrine should be less than 1 microgram/kg; the solution should be diluted to 1:400,000 concentration, and the injection, after careful aspiration, should be performed over at least five minutes into the less vascular anterior and posterior cervix sites.

Anesthesia, Epidural↗
PubMed1983

Single injection spinal anaesthesia with amethocaine and morphine for transurethral prostatectomy.

The intrathecal administration of amethocaine plus morphine as an anaesthetic technique for providing surgical anaesthesia and postoperative analgesia was evaluated in 24 patients undergoing transurethral resection of the prostate. The efficacy of the technique was compared with that observed following spinal anaesthesia with amethocaine alone. Twelve patients (group I) received spinal anaesthesia with amethocaine 12-14 mg and a further 12 patients (group II) received spinal anaesthesia with amethocaine 12-14 mg plus morphine 1 mg. In group II the addition of morphine 1 mg to the amethocaine produced excellent surgical anaesthesia and postoperative analgesia and these patients had significantly less postoperative pain than the patients who received amethocaine alone. There was a high frequency of side-effects associated with intrathecal morphine in group II, for example, subtle respiratory depression, nausea, vomiting and pruritus.

Aged↗