Biomedical subjects

K Evans

Publications and source records attributed to K Evans.

At least 19 recordsLinked to original sources

PubMed1992

Factors affecting cervical anastomotic leak and stricture formation following esophagogastrectomy and gastric tube interposition.

Following esophagectomy, restoration of swallowing by gastric tube interposition with cervical esophagogastric anastomosis reduces morbidity and mortality associated with intrathoracic anastomoses at the expense of an increased incidence of both anastomotic leak and stricture formation. A retrospective study of 165 patients with either squamous cell carcinoma or adenocarcinoma of the distal esophagus or gastric cardia undergoing esophagogastrectomy with gastric tube interposition and cervical anastomosis at Vancouver, British Columbia, or London, Ontario, was undertaken. Forced-entry multiple logistic regression analysis of factors believed to influence anastomotic outcome was performed. Anastomotic leak occurred in 17% of patients; statistically significant correlation with low preoperative serum albumin (p = 0.005), running suture technique (p = 0.029), high intraoperative blood loss (p = 0.038), and the occurrence of postoperative delayed gastric emptying (p = 0.045) was found. Anastomotic strictures occurred in 31% of patients; a statistically significant correlation was found with preceding anastomotic leak (p = 0.001) and intraoperative blood loss (p = 0.042). Factors including preoperative radiotherapy and diabetes mellitus were not found to be significant.

Anastomosis, Surgical↗

PubMed1992

Manipulation of the fractured nose under local anaesthesia.

Simple fractures of the nasal pyramid without significant septal deformity may be reduced as effectively under local as under general anaesthesia. Currently, the former may involve regional nerve blockade by intranasal infiltration and is often unpleasant. We have attempted to find a more acceptable method. Fifty consecutive, adult patients with clinically displaced nasal fractures were randomized to receive either blocks of the infraorbital, infratrochlear and external nasal nerves by intranasal infiltration or generalized infiltration of the nasal dorsum by an external route. All patients received intranasal cocaine. Following manipulation, each patient recorded their overall discomfort level and subjective nasal airway patency. The surgeon recorded the cosmetic result. Analysis revealed the internal route to be significantly more painful (P less than 0.001) and with no advantage to the patient with respect to post-operative airway patency or cosmesis. We recommend the technically easier external method for this procedure.

Adult↗

PubMed1992

Effect of synchronous and asynchronous pulsatile flow during left, right, and biventricular bypass.

Ventricular assist devices augment flow from the left atrium to the aorta and/or from the right atrium to the pulmonary artery. Most devices are used in the asynchronous full-to-empty mode (asynchronous) but may also be used in a synchronous counterpulsation mode (synchronous). This study determines the optimal assist modes to reduce myocardial oxygen consumption (MVO2) and metabolism. Twelve pigs were instrumented with carotid artery and Baim coronary sinus catheters for determination of MVO2 and myocardial lactate production (LACT). Six were implanted with a Pierce-Donachy left ventricular assist device (LVAD) and 6 with both right and left ventricular assist devices (BIVAD). Two periods each of control, synchronous, and asynchronous bypass were instituted, the midanterior descending coronary artery (LAD) was ligated, and the sequence was repeated. After each period, MVO2 and LACT were determined and myocardial biopsy specimens were obtained for tissue, lactate, and ATP assay. Following LAD ligation, biopsy specimens were obtained from both the infarct and noninfarct zones of the heart. MVO2 decreased (p < 0.05) in the asynchronous BIVAD mode compared with control. MVO2 was unchanged in synchronous BIVAD or either LVAD mode. Tissue ATP and tissue lactate were unaffected by any mode of bypass. Only BIVAD in the asynchronous mode reduced MVO2. When ventricular assist devices are utilized to aid recovery of the natural heart, two devices should always be inserted to allow biventricular assist. Synchronous counterpulsation offers no advantage.

Adenosine Triphosphate↗

PubMed1992

Intraocular pressure measurement in children using the Keeler Pulsair tonometer.

A study to determine whether Keeler Pulsair tonometry is a feasible alternative to tonometry under general anaesthesia in children was undertaken. We recruited 53 children aged from 6 months to 9 years old. Readings were obtainable from 78% and a complete set of four readings from each eye was obtained from 45% of the group in an out-patient setting. Averaged Pulsair measurements agreed well with Perkins applanation tonometry values under general anaesthesia. Techniques to improve compliance are discussed. In conclusion, the Pulsair tonometer is a viable method for obtaining estimates of intraocular pressure in children in this age-group.

Anesthesia, General↗

PubMed1992

Changes in total body bone mineral content and regional bone mineral density in renal patients following renal transplantation.

We performed serial measurements of total body bone mineral content (BMC) and bone mineral density (BMD), and of regional BMD at the lumbar spine and femoral neck using dual energy X-ray absorptiometry. Twenty-six patients (15 females and 11 males) were studied at the time of transplantation, and 3 and 6 months post-transplant. At baseline, the total body BMC and regional BMD values of the patients did not differ significantly from age- and sex-matched controls. Total body BMC had fallen progressively at 3 months, followed by partial recovery at 6 months. Significant decreases of BMD were seen in the lumbar spine and femoral neck at 3 months with no evidence of recovery at 6 months. The changes in these indices correlated well with the duration of hospital stay in the first 3 post-transplant months. This preliminary study demonstrated rapid deterioration of skeletal integrity following renal transplantation and that this might be progressive. Preventative strategies to avoid this early bone loss may need to be investigated.

Absorptiometry, Photon↗

PubMed1991

Hemoperitoneum secondary to traumatic rupture of an adrenal tumor in a dog.

Hemoperitoneum secondary to traumatic rupture of an adrenocortical adenocarcinoma was diagnosed in a 10-year-old male dog. Immediate surgical attention was required to remove the tumor and to control hemorrhage. The dog appeared to develop transient hypoadrenocorticism after surgery, but recovered with short-term exogenous corticosteroid administration. At 6 months after surgery, the dog was clinically normal.

Adenocarcinoma↗

PubMed1991

Cleft anterior segment with maternal hypervitaminosis A.

We report a case of an 'hourglass' cornea and iris with reduplicated lens in the left eye of an infant girl. An excess of vitamin A products had been taken by the mother during pregnancy. Mechanisms by which vitamin A excess could have caused this are discussed.

Abnormalities, Drug-Induced↗

PubMed1991

Achievement of objectives: internal medicine fourth year clinical clerkship.

The clinical clerkship in Canadian Medical Schools is intended to provide senior medical students with opportunities to gain practical knowledge of clinical medicine, develop technical skills, learn to use judgement and experience first-hand clinical decision making. Assessment of rotations in internal medicine were undertaken in order to understand more fully the nature of medical clerkship experiences. We found that medical clerks in our programme were exposed to a high proportion of undifferentiated problems and an adequate case mix. They performed a wide range of technical procedures. There were, however, certain gaps in the clerks' experiences both in the specialty areas, and in therapeutic and technical procedures. Recognition of these gaps in the clerkship experiences suggest that further deliberation of goals and objectives is required and issues of achievement of competencies need to be addressed.

Adult↗

PubMed1991

Standard setting: an introduction to differing approaches.

In recent years there have been widespread developments in the National Health Service concerning quality assurance programmes. Differing approaches have been established throughout the United Kingdom and to individuals new to the field it is easy to become confused with the wide range of approaches described in many nursing and health service journals. A common theme in all such programmes involves defining the standard of service to be provided, then attempting to measure that service. This article will examine four different approaches to standard setting based on a multidisciplinary discharge standard. The process of setting the standards will be described and critiqued in each case, and this will be followed in the final section by a discussion of the different approaches.

Humans↗

PubMed1991

Estimation of technetium-99m-MAG3 renal clearance in children: two gamma camera techniques compared with multiple plasma samples.

Dynamic renal scintigraphy using technetium-99m mercaptoacetylglycylglycylglycine (MAG3) has been described in adults, and clearance values have been established using multiple plasma samples. This study of renal clearance has compared two fundamentally different gamma camera techniques (both of which require a single blood sample) with the multiple blood sampling technique in children (n = 30). Results show that a 40-min dynamic 99mTc-MAG3 renal scintigram coupled with a single plasma sample will allow analysis of the data so that clearance values, which are similar to those from multiple plasma samples, may be calculated. The curve generated from the cardiac region of interest (ROI) provided clearances values that had a high correlation coefficient (0.939-0.951) compared to the multiple-plasma sample technique immaterial of the timing of the blood sample. The renal uptake method of clearance had a lower correlation coefficient (0.89-0.92), which varied with the timing of the blood sample compared to the multiple-plasma sampling technique. This study has demonstrated that an extended gamma camera acquisition coupled with a single-plasma sample may be used for quantitative renal function studies using 99mTc-MAG3.

Adolescent↗

PubMed1990

Quantitation of vesico-ureteral reflux by radionuclide cystography and urodynamics.

A method is described for the quantitation of vesico-ureteral reflux by synchronous combined direct radionuclide cystography and urodynamics. Intravesical pressures and volumes are co-ordinated with volumes of reflux. Peak reflux volumes in 11 children diagnosed as having severe (grades 3-4) reflux on conventional contrast cystography ranged from 1 to 50 ml/kidney. A number of different patterns of reflux were observed. Reflux may occur progressively throughout low pressure filling or incrementally with unstable bladder contractions. Reflux during voiding may be maximal as detrusor pressure falls. The method requires wider application to explore the potential for a functional classification of the reflux problem.

Child↗

PubMed1990

Physical determinants of the endocardial P wave.

UNLABELLED: Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pacemakers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. RESULTS: the mean supine PWA increased on full inspiration (3.56 +/- 1.3 mV versus 3.25 +/- 1.2 mV during quiet respiration, P less than 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 +/- 1.2 mV increasing to 3.49 +/- 1.3 mV, P less than 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 +/- 1.2 with exercise, and 3.47 +/- 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. CONCLUSIONS: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions.

Adolescent↗

PubMed1990

True incidence of pacemaker syndrome.

Although the purported incidence of pacemaker syndrome according to the literature is only 5%-15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either VVI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (P less than 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough, and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the VVI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical, hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode.

Aged↗

PubMed1989

The accumulation of organotins in adult and seed oysters from selected estuaries prior to the introduction of U.K. regulations governing the use of tributyltin-based antifouling paints.

Between April and November, 1985, a study of the levels of organotins in adult and seed Crassostrea gigas grown in the southwest and southeast of England was carried out. This work corresponds with a similar study of organotin water levels (reported separately). The analytical procedure used was directly coupled high performance liquid chromatography-flame atomic absorption spectrometry. Individual adult oysters and groups of 20-40 seed oysters were taken for analysis on a monthly basis. The profiles of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) are discussed in relation to each other and levels found in the waters. In general, levels of all three organotin species were found to be higher in the seed oysters. Mean levels of TBT reached 3.1 micrograms g-1 in seed oysters from the Exe, Devon, in October, whereas mean levels of DBT and MBT reached 16.1 and 16.7 micrograms g-1 in Teign, Devon, seed oysters in October. Bioconcentration factors of approximately 1000 were found, but seem to be greater when lower levels of TBT were present in the water, perhaps indicating a more 'efficient' removal from the water. The degree of shell thickening was calculated for all oysters submitted for analysis. The highest percentage of adult oysters with severely thickened shells was found at Tollesbury Fleet, where 61% of oysters showed shell thickness index values of six or less. Generally, two peaks in TBT levels in the oysters were observed, in the late spring and early summer: these seem to correlate with peak levels of TBT in the waters immediately preceding these times. A large proportion of the DBT and MBT found in the oysters seems to come from the metabolism of the TBT ingested. It is suggested that high sediment loadings may contribute to the severe deformation of oysters grown at Tollesbury Fleet, but only in the presence of TBT.

Aging↗

PubMed1989

Impact of new radiotherapy modalities on the surgical management of cancer of the esophagus and cardia.

At the Cancer Control Agency of British Columbia, 483 patients with cancer of the esophagus and cardia were seen from 1970-1980. Four hundred and one out of 483 (83%) had tumors larger than 5 cm (T2) and in 288/483 (60%) the disease had extended beyond the esophageal wall (T3). The overall 5-year survival rate was only 9% for all patients treated by external irradiation. The 5-year survival for a selected group having esophagectomy was 20%. Most patients died of persistent cancer at the primary site (83%); the cause of death was aspiration pneumonia (82%) due to obstruction caused by the persistent cancer. Our most recent experience using intracavitary irradiation either prior to or after external irradiation in 211 patients has been safe and simple and preliminary analysis of treatment results suggests that it has improved the therapeutic ratio. The analysis of quality of life at 6 months following therapy as it relates to performance status, swallowing ability, weight, and pain indicated significant improvement in all of these parameters. Of 171 patients, 33% were still alive at 1 year, 26% at 2 years, and 19% at 3 years following treatment. Of 43 patients suitable for preoperative irradiation, only 26 patients were actually resected and 19 of them are still alive with no evidence of disease, 8 to 30 months. The rationale and technical aspects of the combined treatment are described in detail. Treatment results, complications and an outline for future programs based on this experience are also described.

Body Weight↗

PubMed1988

Two routes for 99mTc-DMSA uptake into the renal cortical tubular cell.

Critical factors determining the renal handling of 99mTc-dimercaptosuccinic acid (DMSA) are protein binding in plasma and the renal 99mTc-DMSA extraction efficiency. Comparison of the count rate over soft tissue with that over the cardiac blood pool about 1 h after injection demonstrated that 99mTc-DMSA is not exclusively an intravascular label. 99mTc-DMSA was 76% protein bound in plasma as demonstrated by HPLC and gel filtration. Assuming that the 24% that is not protein bound is filtered at the glomerulus, the renal extraction efficiency of 99mTc-DMSA by glomerular filtration is about 5%. Since the total renal extraction efficiency was also found to be about 5%, the majority of the activity that becomes fixed in the renal cortex arrives there as a result of filtration followed by tubular reabsorption rather than by direct extraction from peritubular blood. However, discordant changes in DMSA and DTPA uptake induced by captopril in renovascular hypertension (RVH) suggested that a minority of uptake was by direct peritubular extraction. This kinetic model was supported by indirect measurement of protein binding and extraction efficiency based on the kinetics of 99mTc-DMSA disappearance from plasma and kinetics of uptake in the kidneys. Furthermore, differential functional studies based on 99mTc-DMSA and 99mTc-DTPA before and after captopril in patients with RVH due to unilateral renal artery stenosis confirmed filtration followed by tubular reabsorption as the predominant route for DMSA uptake by the kidney.

Adult↗

PubMed1988

The biodistribution and pharmacokinetics of meta-iodobenzylguanidine in childhood neuroblastoma.

MIBG is generating considerable interest for the treatment of neuroblastoma. This study has investigated the biological variation in handling of the compound in children with neuroblastoma. The biodistribution of the compound has been characterised in children undergoing tracer administrations of 123I and 131I-mIBG. Estimates of hepatic and whole body radiation dose delivery have been made. The results indicate substantial interpatient variation in hepatic dose delivery. This organ may be critical in some patients undergoing targeted radiotherapy with mIBG.

3-Iodobenzylguanidine↗

PubMed1988

Background in 99Tcm DTPA renography evaluated by the impact of its components on individual kidney glomerular filtration rate.

Following injection for renography, 99Tcm-labelled diethylenetriamine-pentacetic acid (DTPA) rapidly enters the extravascular space. Background therefore comprises two components, a falling intravascular signal and an extravascular signal which initially rises. We estimated the relative magnitudes of these two components in terms of their impact on the calculation of differential renal function and individual kidney glomerular filtration rate (IKGFR) from the second phase of the 99Tcm-labelled DTPA renogram in 56 paediatric kidneys. We expressed each of the two background signals as a GFR equivalent. The GFR equivalent of the intravascular signal recorded from a peri-renal background region of interest (ROI), scaled by a factor equal to the ratio of the pixel numbers in the renal and background ROIs, was -39 (S.D. 14) ml min-1. The GFR equivalent of the extravascular signal was smaller than this and opposite to it at 23 (S.D. 10) ml min-1, giving a median ratio for the two equivalents of -1.68. Because of the opposing effects of the two background components on the second phase of the renogram, techniques recently described for the quantification of IKGFR from the renogram, and which eliminate the intravascular component, offer no theoretical advantage over a method of analysis which uses 'direct' subtraction of the total background signal. In practice, however, these new techniques are superior in their handling of 'noisy' data, consistently giving a lower coefficient of variation in their estimation of IKGFR.

Child↗