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Biomedical subjects

L C Jenkins

Publications and source records attributed to L C Jenkins.

At least 19 recordsLinked to original sources
PubMed1992

Continuous lumbosacral block using a Tuohy needle and catheter technique.

Three cases are reported where continuous lumbosacral block was performed using a catheter through an epidural needle technique. Good unilateral lower limb surgical anaesthesia was achieved in all three cases with successful blockade of the lumbar and sacral plexuses. A 17-gauge Tuohy needle was positioned between the transverse processes of L4 and L5 and an epidural catheter inserted into the space between the quadratus lumborum and psoas muscles. Forty to seventy millilitres of local anaesthetic were injected and resulted in good surgical anaesthesia within 12-20 min. Radiographic studies in these patients confirmed placement of the catheter in close proximity to the lumbosacral plexus. Experience in a further 12 cases is also reported. There were no side-effects. The technique is successful and is recommended when unilateral lower limb anaesthetic is required and when spinal and epidural anaesthesia are contraindicated.

Aged↗
PubMed1991

Technique for preparing cross-section transmission electron microscope specimens from ion-irradiated ceramics.

The general techniques necessary to produce a high-quality cross-sectioned ceramic specimen for transmission electron microscope observation are outlined. A particularly important point is that the width of the glued region between faces of the ceramic specimen must be less than 0.2 micron to prevent loss of the near-surface region during ion milling. A recently developed vise for gluing ceramic cross-section specimens is described, and some examples of the effect of glue thickness on specimen quality are shown.

Calibration↗
PubMed1990

Dipyridamole-thallium myocardial scanning in the preoperative assessment of patients undergoing abdominal aortic aneurysmectomy.

Dipyridamole thallium scanning (DTS) is an imaging technique with good sensitivity for coronary artery disease (CAD). The purpose of this study was to compare the haemodynamic courses and the correlation between pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) in patients with normal DTS (Group 1: n = 12) with those whose scans demonstrated CAD (Group 2: n = 11). Haemodynamic profiles were obtained prior to anaesthesia and at several times during surgery. The haemodynamic courses in both groups were similar with significant decreases in cardiac index, stroke index, and left ventricular stroke work index during aortic cross-clamping compared with values prior to anaesthesia. There were no significant changes in PCWP and CVP throughout the study. The correlations between PCWP and CVP were significant in both groups as were the correlations between the changes in PCWP and the changes in CVP observed at the time of cross-clamping. These correlations all had large standard errors of the estimate, however, making it impossible to predict the PCWP from the CVP with precision. It is concluded that, in a limited study population, an abnormal DTS did not identify patients in whom the PCWP and CVP correlated poorly during abdominal aortic aneurysmectomy.

Aged↗
PubMed1990

Hospital admissions from the Surgical Day Care Centre of Vancouver General Hospital 1977-1987.

The admissions to Vancouver General Hospital from its Surgical Day Care Centre were reviewed for the period 1977 to 1987. The overall mean rate of admission for the period was 0.28 per cent, for surgically-related admissions 0.22 per cent and for anaesthesia-related admissions 0.07 per cent. The principal reasons for surgery-related admissions were postoperative bleeding, complications, the need for further surgery, the requirement for prolonged postoperative care, and pain. Urology had a particularly high percentage of admissions compared with its workload, because of the diagnostic nature of much of the work. Anaesthesia-related admissions included "syncope," lack of an accompanying adult, aspiration pneumonitis and coincident acute disease. Twelve of the 14 patients admitted with syncope had surgery in the afternoon and had received less than ideal amounts of intravenous fluid. Seven of the 12 ASA physical status II patients admitted had an admission diagnosis related to the coincident disease.

Ambulatory Surgical Procedures↗
PubMed1989

Comparison of end-tidal carbon dioxide, oxygen saturation and clinical signs for the detection of oesophageal intubation.

The reliability of various methods for detecting oesophageal intubation was assessed by means of a single blind study in rats. Both oesophagus and trachea were simultaneously intubated. The presence or absence of various clinical signs was noted during tracheal or oesophageal ventilation and arterial blood gases and end-tidal CO2 were measured. Oesophageal ventilation for one minute was associated with significant decreases (P less than 0.001) in pH, PaO2 and SaO2 and a significant (P less than 0.001) increase in PaCO2. Although mean PaO2 decreased by 70 per cent and mean SaO2 decreased by 31 per cent, 43 percent of rats failed to demonstrate a decrease in SaO2 below 85 per cent. Oxygen saturation was the least reliable method for detecting oesophageal intubation (sensitivity = 0.5, specificity = 0.9, positive predictive value (PPV) = 0.8). Chest movement was the most reliable clinical sign for detecting oesophageal intubation (sensitivity = 0.9, specificity = 1.0, PPV = 1.0). Oesophageal rattle was the second most reliable clinical sign (PPV = 0.9). Moisture condensation in the tracheal tube (PPV = 1.0) and abdominal distension (PPV = 0.9) were judged to be the least reliable because each had a high false negative rate of 0.3. The most reliable method for the early detection of oesophageal intubation in rats was end-tidal, CO2 (sensitivity 1.0, specificity = 1.0, PPV = 1.0). In addition, end-tidal CO2 when used in conjunction with the four clinical signs improved the reliability of these signs.

Abdomen↗
PubMed1989

Surgery in Jehovah's Witnesses.

This is a retrospective study of the outcome of surgical procedures in patients who were Jehovah's Witnesses. Over a 75-month period, 58 Jehovah's Witness patients had 78 surgical procedures at the Vancouver General Hospital. Three patients had preexisting anaemia of less than 100 g.L-1 haemoglobin. Postoperative haemoglobin concentration decreased below 50 g.L-1 in three patients. One patient had a postoperative haemoglobin of 34 g.L-1 (haematocrit 10.1 per cent) and survived. One patient died from uncontrollable postoperative haemorrhage. Perioperative morbidity was not uncommon, including significant hypotension (eight cases), cardiac arrhythmias (six), myocardial ischaemia (three), excessive bleeding (four), postoperative nausea or syncope (four), and wound or urinary tract infection (four).

Adolescent↗
PubMed1989

Method for noninvasive determination of arterial PCO2 in anesthetized rats.

A method for the noninvasive determination of arterial PCO2 in mechanically ventilated rats is presented. In normotensive, rats under steady state conditions where a depth of anesthesia adequate to abolish spontaneous ventilatory effort was used, end-tidal CO2 and arterial PCO2 were highly correlated (r = 0.96; p less than 0.001). The regression equation for this relationship was: PaCO2 (mmHg) = 6.757 +/- 8.984 ETCO2(%). This method obviates the need for arterial cannulation and may be useful in neuropharmacological research in rats when knowledge of arterial CO2 alone is required.

Anesthesia↗
PubMed1988

Use of a Doppler ultrasound stethoscope for intercostal nerve block.

Two cases with rib injuries are reported where intercostal nerve block without rib palpation was safely and successfully performed on six separate occasions using a Doppler blood-flow detector ultrasound stethoscope. A third case studied by a radiologist using a pulsed Doppler flowmeter, determined the source of the Doppler signals as originating from the intercostal artery. The significance of these findings is discussed.

Adult↗
PubMed1988

Detection of interruptions in the breathing gas of ventilated anaesthetized patients.

Interruption of the breathing gas to a ventilated anaesthetized patient due to accidental disconnection or anaesthesia system malfunction may have serious consequences if not detected quickly. A series of tests which covers the range of foreseeable mechanical problems was developed and used to test the performance of three breathing gas interruption monitors, two commercially available and one developed at Vancouver General Hospital. The tests were designed to evaluate the performance of monitors as installed on anaesthesia systems under a variety of failure conditions, including endotracheal tube disconnection with and without occlusion of the opening, kinks in the inspiratory and fresh gas hoses, disconnection of the fresh gas hose, leaks in the breathing circuit, excessive high or low pressure in the scavenging circuit, continuing high breathing circuit pressure, and kinks in the circuit pressure sensing hose. Ability to detect both significant changes in ventilation variables and faults existing at initiation of ventilation were also tested over a representative range of ventilator and patient variables using circle, coaxial and paediatric circuits. Only complete endotracheal tube disconnections with no obstruction of the opening were reliably detected by all three monitors. A commercial monitor with a single fixed-threshold alarm level also detected fresh gas interruptions in circle and adult coaxial circuits, but failed to alarm in response to any other fault condition. A monitor with selectable pressure thresholds and high, low, and continuing pressure limits detected just under half of the fault conditions. A microprocessor-based monitor developed at Vancouver General Hospital detected and correctly identified roughly 80 per cent of the faults. The series of tests forms the basis for a Canadian Standards Association Preliminary Standard (Z168.10) and will allow hospitals to test the performance of breathing gas interruption monitors in use in their institutions. Comments on the test series are solicited.

Anesthesia↗
PubMed1988

Evaluation of a postocclusive reactive circulatory hyperaemia (PORCH) test for the assessment of ulnar collateral circulation.

This prospective double-blind study compared Doppler assessment of the ulnar collateral circulation with the Allen's test and a postocclusive reactive circulatory hyperaemia (PORCH) test in 144 patients (288 hands). The PORCH test involves inflation of a blood pressure cuff on the upper arm to a supra systolic (+50 mmHg) pressure for two minutes. Prior to cuff deflation, both radial and ulnar arteries are occluded at the wrist; the cuff is then deflated and a 15-second period allowed so as to restore blood flow down to the wrist. Ulnar artery compression is now released and the time to revascularization measured. Fifty-eight per cent of hands with an abnormal Allen's test had a normal ulnar collateral circulation. Results of Allen's test were not significantly affected by patients' sex or smoking status (p greater than 0.1) but there was a significant difference (p = 0.001) in the false positive rates between patients over 40 years of age (0.2) and those under 40 years of age (0.03). Results of the PORCH test were not significantly affected by patients' age, sex or smoking status (p greater than 0.1). With a revascularisation time of 19 sec as a "cut off" for ulnar abnormality the PORCH test, unlike the Allen's test, was perfectly predictive of an abnormal ulnar collateral circulation and had no false positives.

Aged↗
PubMed1988

Magnesium and the anaesthetist.

Magnesium plays an important role as a cofactor in many of the body's critical functions and reactions. A deficiency or excess of extracellular magnesium can produce significant signs and symptoms. Hypomagnesaemia is a common finding in hospitalised patients, especially those in critical care areas. Anaesthetising hypomagnesaemic patients may exacerbate pre-existing cardiovascular disease and increase the risk of perioperative dysrhythmias. A low serum magnesium level usually suggests a total body deficiency of magnesium. Treatment of magnesium deficiency is by parenteral magnesium and should be instituted prior to surgery. Hypermagnesaemia is often iatrogenic and is more likely in patients with renal dysfunction who are receiving oral or parenteral magnesium. The specific antidote is intravenous calcium. Anaesthetised patients with high serum magnesium levels are at risk from hypotension, potentiation of non-depolarising neuromuscular blockers, postoperative respiratory failure and cardiac arrest.

Anesthesia↗
PubMed1986

Prevalence of hepatitis B in anaesthesia personnel.

Hepatitis B virus (HBV) infection, an occupational risk to anaesthetists, varies widely in incidence throughout the world. This study was undertaken to define the prevalence of previous HBV infection in anaesthesia personnel in the teaching hospitals of metropolitan Vancouver. Participants donated a blood sample and completed a questionnaire. Overall participation rate was 90.4 per cent. No participants were HBV carriers. Ten of 83 anaesthetists (12 per cent) had antibodies to HBV while all anaesthesia residents were seronegative. Anaesthetists with HBV antibodies tended to be either older or foreign born. Standard precautions taken by anaesthetists such as use of preoperative questioning of a patient's hepatitis status or the use of gloves when handling body fluids of a suspected or proven HBV carrier could not be shown to affect this seropositivity rate. This study, consistent with others, suggests that anaesthetists are at risk for acquiring HBV infection from occupational exposure. This risk appears to be somewhat less than that for surgeons, dentists, and staff of dialysis and urban emergency units.

Anesthesiology↗
PubMed1986

A survey of obstetric anaesthesia practice in British Columbia.

Hospitals and anaesthetists in British Columbia were surveyed by means of questionnaires to assess patterns of obstetric anaesthesia practice, qualifications and numbers of obstetric anaesthesia personnel, hospital obstetric facilities and facilities and protocols for neonatal resuscitation. It was apparent that a large proportion of the obstetric anaesthesia service in this province was being provided by physicians who were not trained, nor certified, as anaesthesia specialists. Preanaesthetic assessment in the obstetric units differed in attitude and practice from the standards expected in the general operating rooms. There was also in community hospitals a significant incidence of failure to follow certain accepted safe practices (in obstetric patients), such as preinduction hydration and oxygenation, cricoid pressure during intubation and prevention of aortocaval compression. However, administration of general anaesthesia without endotracheal intubation, was rare in this survey. Post-anaesthetic recovery facilities in obstetric units were conspicuously deficient, even in the larger hospitals. The majority of community hospitals lacked written protocols for neonatal resuscitation; and the number of institutions reporting that the neonatal heart rates and temperatures were not routinely monitored is of concern. It is recommended that minimum standards for training in obstetric anaesthesia should be clearly defined; and provision should be made for revision and upgrading of knowledge and skills for physicians practicing anaesthesia in smaller community hospitals.

Anesthesia, Epidural↗