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Biomedical subjects

F M Khan

Publications and source records attributed to F M Khan.

At least 19 recordsLinked to original sources
PubMed1992

Beta irradiation of recurrent ptergia: results and complications.

Although postoperative beta irradiation for prevention of pterygium recurrence is widely used, its complication rate has not been widely appreciated. Thirty-six patients underwent pterygium excision followed by irradiation with 90Sr to between 1600 and 5300 cGy (median 2400) in two to four fractions over 7 to 27 days. A median of three fields were used in each treatment course (range two to 10). Most patients had undergone previous treatment for their pterygia, including surgery alone (25 patients), or both surgery and irradiation (5 patients). Overall, recurrences developed in 10 eyes (28%). Recurrence occurred in one eye after re-irradiation (20%), compared to 9 of 31 (29%) previously non-irradiated eyes (p greater than 0.1). There was no association with number of excisions and recurrences, although all but 6 patients had undergone more than one excision. Thirteen patients (36%) developed complications including: epithelial defect or corneal thinning (3), symblepharon (5), cataract (4) and corneal ulceration (1). Complications developed in 4 of the 5 (80%) re-irradiated eyes compared to 9 of 31 (29%) previously non-irradiated eyes (p less than 0.05). The power of the statistical analysis was limited by sample size, but no significant association was observed between the development of complications or recurrences and total dose, number of abutting fields, number of previous surgical excisions or patient age, even when re-irradiated patients were excluded. Recently described calibration uncertainties with the 90Sr applicator may explain in part these complications. Alternatively, technical factors such as the number of fields or volume treated may play a role. Excessive complications and recurrences with the use of postoperative beta irradiation in this series emphasize the danger of re-treatment and the need for alternative safe and effective therapies.

Adolescent↗
PubMed1992

Double-blind comparison of etodolac SR and diclofenac SR in the treatment of patients with degenerative joint disease of the knee.

An on-going multi-centre, double-blind, parallel-group study is being carried out to compare the efficacy and tolerability of sustained-release (SR) formulations of etodolac and diclofenac in patients with degenerative joint disease (osteoarthritis) of the knee. An interim analysis of the findings has been made for 64 patients from two centres which have now completed their part in the study. Thirty-two patients were randomly assigned to receive 600 mg etodolac SR once daily for 4 weeks; the remaining 32 patients received 100 mg diclofenac SR. Primary efficacy assessments rated on a 5-point categorical scale were patient and physician overall assessments of the patient's condition, night pain and pain intensity. Secondary efficacy parameters included weight-bearing pain, stiffness duration, joint tenderness on pressure, degree of swelling and erythema, degree of knee flexion and time to walk 15 metres. The results showed that for both etodolac SR and diclofenac SR treatment groups there was an improvement from baseline in all efficacy parameters at the last visit and no statistically significant difference was observed between treatments. However, although not statistically significant, the improvement rate in the patient's condition at Week 2 was slightly greater in the etodolac SR treatment group, suggesting that improvement may occur more rapidly with etodolac SR than with diclofenac SR. With regard to tolerability, 5 patients in the etodolac SR treatment group and 3 in the diclofenac SR group withdrew from the study because of adverse reactions. Two events (dyspepsia and mouth ulceration) in the etodolac SR group and 4 events (headache, glossitis, depression and insomnia) in the diclofenac SR group were considered to be definitely drug-related. Dyspepsia was reported by 3 patients (1 withdrawal) treated with etodolac SR and by 4 patients (2 withdrawals) treated with diclofenac SR. A statistically significant decrease was observed in haemoglobin and haematocrit values after 4 weeks of treatment in the diclofenac SR group, but this was not considered to be clinically important. In addition, there were no clinically significant changes in blood chemistry and urinalysis for either treatments. In conclusion, the results of the present study indicate that 600 mg etodolac SR once daily for 4 weeks is effective in the treatment of patients with degenerative joint disease of the knee, as is 100 mg diclofenac SR. In addition, both drugs have comparable tolerability profiles.

Aged↗
PubMed1991

Are heat stroke patients fluid depleted? Importance of monitoring central venous pressure as a simple guideline for fluid therapy.

During pilgrimage season (Hajj) in Saudi Arabia 34 patients with heat stroke (HS) were centrally cannulated to assess their state of hydration and fluid requirement during cooling period. Central venous pressure (C.V.P.) measurements indicated that most victims of heat stroke had normal C.V.P. on arrival at heat stroke centres and may not be fluid depleted. Twenty-two patients (64.7%) had normal or above normal C.V.P. Twelve patients (35.3%) had zero or below zero C.V.P. Six patients (17.6%) had above 10 cmH2O (range 10-26 cmH2O) and could have developed acute congestive heat failure and pulmonary edema if they had been transfused at the standard recommended rate of 3-4 litres of fluid during an average cooling time of 1 h as has been practiced in the heat stroke centres to date. This study also showed that heat stroke patients should not be briskly transfused because the heart may be affected by heat stroke per se and an unmonitored challenge by brisk i.v. therapy during cooling (which on its own increases preload on the heart due to peripheral vasoconstriction) can lead to acute overload problems. An average of 1 litre of normal saline or Ringer's lactate (crystalloids) was sufficient to normalize C.V.P. during the cooling period and to restore an optimal state of hydration without predisposing to congestive cardiac failure and pulmonary edema--the potential to develop disastrous adult respiratory distress syndrome and disseminated intravascular coagulopathy.

Central Venous Pressure↗
PubMed1991

Border separation for adjacent orthogonal fields.

Field border separations for adjacent orthogonal fields can be calculated geometrically, given the validity of some important assumptions such as beam alignment and field uniformity. Thermoluminescent dosimetry (TLD) measurements were used to investigate dose uniformity across field junctions as a function of field separation and, in particular, to review the CCSG recommendation for the treatment of medulloblastoma with separate head and spine fields.

Cerebellar Neoplasms↗
PubMed1991

Tracheal soiling with blood during intranasal surgery--comparison of two endotracheal tubes.

Sixty adult patients, ASA Classes I & II, were involved in a study to compare the effectiveness of Mallinckrodt Hi-Lo-Evac tube and Portex blue line tube in preventing soiling of the lower airways during intranasal surgery. The Hi-Lo-Evac tube with and without pack was significantly more effective than the Portex tube with pharyngeal pack (P less than 0.002) and (P less than 0.01 respectively). There was no significant difference when the Hi-Lo-Evac tube was used with or without a pack (P greater than 0.2). The more effective protection of the lower airways by the Hi-Lo-Evac tube is attributed to the facility of subglottic aspiration during surgery. It is suggested that the Hi-Lo-Evac tube could be used with safety during intranasal surgery in order to reduce postoperative morbidity associated with the use of pharyngeal pack.

Adolescent↗
PubMed1989

An afterloading brachytherapy device utilizing thermoplastic material.

An afterloading brachytherapy device for treatment of residual cancer in an enucleated orbit with two cesium-137 sources was designed using a thermoplastic material, Aquaplast. The device consists of a face-mask support held in place with elastic bands around the head and an acrylic afterloading applicator. The device is very easy to make, holds the sources firmly in place, allows full mobility of the patient, and gives excellent dose distribution to the target area. It was easily tolerated by a 7-year-old child during the 50 h of treatment.

Brachytherapy↗
PubMed1989

Total skin electron arc irradiation using a reclined patient position.

Several techniques for the treatment of the total skin of the patient using electron beams have been described in the literature. However, most techniques presuppose that the patient is capable of maintaining a standing position for the duration of the treatment. For patients either weakened by disease or those suffering from a loss of limbs, this is often an unrealistic expectation. We will describe a total skin electron irradiation technique that allows the patient to remain in a reclined position without sacrificing dose uniformity. This technique uses two symmetric +/- 48 degrees arc electron beams to provide a field uniformity of +/- 5% over a range of approximately 250 cm X 45 cm. Six patient positions are used to provide a uniform dose around the periphery of the patient. A description of the treatment technique along with details of the dosimetry are given.

Electrons↗
PubMed1988

Quality control of custom-made compensators.

This paper describes a method for routinely checking the accuracy of individual cerrobend compensators made for use with the Varian Clinicomp-100. The Reduction Ratios (for a given beam energy) are provided for select depth of compensation and field size. It is important to check each compensator before commencing treatment to identify possible operation error and ensure proper filling of the styrofoam with cerrobend. This verification process involves: (1) choosing several points at which the tissue deficit is known; (2) exposing a ready-pack film (Kodak XV-2) in a polystyrene phantom at a suitable depth, both with and without the compensator in place (the dose to which the film is exposed is within the initial linear range of the H and D curve); (3) determining the optical density at the above chosen points; and (4) comparing the O.D. ratios corresponding to the compensated and uncompensated conditions to the Tissue Maximum Ratios (TMRs) for the proper depths at these points. The method of this technique is also incorporated into the quality control check of other compensators, for example, acrylic, brass c-wedges, etc.

Humans↗
PubMed1988

Oculocardiac reflex during excision of periorbital tumor--a case report.

The occurrence of oculocardiac reflex causing severe bradycardia and hypotension during the excision of a large, hemorrhagic, periorbital tumor in a 66 year old male is presented. The reflex occurred despite complete destruction of the eye by the tumor. Intravenous atropine, 0.5 mg, restored both the heart rate and blood pressure and prevented further occurrence of the reflex during the rest of the operation.

Aged↗
PubMed1985

Gas exchange during microsurgery of the larynx using Foley catheter insufflation technique--preliminary results.

The technique of insufflating anesthetic gases via oro-tracheal Rusch type Foley catheter with spontaneous ventilation for microsurgery of the larynx is described. Fifteen unselected patients were used to assess the adequacy of gas exchange with this technique. Arterial blood gas analysis was carried out 5 minutes and 25 minutes after induction of anesthesia. The results at 25 minutes indicate adequate gas exchange. There was a significant increase in the PaO2 at 25 minutes but the decrease in PaCO2 at 25 minutes was insignificant. The technique also provided very satisfactory conditions for surgery with only minimal risk of gross tracheal soiling. No dysrhythmias were encountered and there was hemodynamic stability in all cases.

Adolescent↗
PubMed1985

Antacid regimen in reducing gastric fluid acidity--comparison of conventional oral antacids with cimetidine.

281 patients, divided into two groups, were given single 30 ml dose of five different conventional oral antacids (sodium citrate, 0.3 M Maalox, Gelusil, Alludrox and Mucaine), separately and in combination with Cimetidine to study their effect on decreasing the acidity of stomach contents. In 181 patients receiving varying types of conventional oral antacids, 2-10 percent of the patients had pH less than 3, regardless of the antacid received. In 100 patients of Cimetidine plus antacid group, none of the patients had pH less than 4.83, maximum being 8.2. With thick particulate oral antacids, no-mix between gastric juice and antacid was noticed in approximately 5-10 percent of cases. Cimetidine combined with oral antacid was the safest regimen to reduce the gastric fluid acidity.

Adolescent↗
PubMed1983

Monte Carlo evaluation of the Sievert integral for brachytherapy dosimetry.

The Sievert integral, widely used to compute dose distributions about filtered line sources, assumes that the emitted energy fluence is exponentially attenuated by the filter thickness traversed by the primary photons. To evaluate this approximation, a Monte Carlo simulation was performed realistically modelling the diffusion and energy degradation of primary photons due to coherent, incoherent and photoelectric interactions in the source filter. Estimates of the exposure rate at points near the source were obtained using analytical averaging. Comparison of the two models shows that for 226Ra and 192Ir sources, the Sievert algorithm consistently overestimates the exposure rate per unit activity. However, such errors may be significantly reduced if source intensity is expressed in terms of exposure rate. Computed exposure rate distributions based on exposure rate calibrations are also less sensitive to uncertainties in available spectroscopic data.

Brachytherapy↗