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Biomedical subjects

R C Nair

Publications and source records attributed to R C Nair.

At least 19 recordsLinked to original sources
PubMed2004

Post pressure hyperemia in the rat.

In prior studies in man, we have demonstrated that pressure-induced hyperemia lasts for prolonged periods as compared to the short-term hyperemia created by proximal arterial occlusion. We have analyzed this phenomenon in our well-studied rat model of skin blood flow. Skin blood flow was measured using laser Doppler techniques in Wistar Kyoto rats at the back, a nutritively perfused site, and at the plantar surface of the paw, where arteriovenous anastomotic perfusion dominates. A customized pressure feedback control device was used to vary applied pressures. At the back, pressures in excess of 80 mmHg resulted in occlusion, whereas at the paw 150 mmHg was required. The peak hyperemic flow after release of pressure was comparable to that elicited by proximal arterial occlusion with a blood pressure cuff. However, the post pressure hyperemia peak descended to a plateau value, which was 50-100% greater than baseline and continued for up to 20 min while the peak following proximal arterial occlusion returned to baseline within 4 min. At the back, post pressure hyperemia reached a maximum after application of 100 mmHg pressure. The application of higher pressures than required for occlusion produced no greater hyperemic response. At the paw, maximum post pressure hyperemia occurred at 100 mmHg, although this pressure level was not totally occlusive. Higher pressures resulted in no greater hyperemia. At the back, 10 min of occlusion produced a maximal peak value whereas 1 min was sufficient at the paw. The application of pressure to a heated probe with subsequent release, produced a hyperemic response. Normalized to baseline blood flow, there was no difference between the hyperemic responses at basal skin temperature and at 44 degrees C. There is a prolonged hyperemic response following local pressure occlusion compared to a much shorter period following proximal ischemic occlusion. One can presume two different mechanisms, one related to ischemia and the other a separate pressure related phenomenon. The thermal vasodilatory response is additive, not synergistic with the post pressure hyperemia we have demonstrated. This finding suggests that different mechanisms are involved in thermal vasodilation and post pressure hyperemia.

Animals↗
PubMed2001

Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model.

AIMS: To develop and apply a quantitative protocol for assessing the transfer of bacteria from bleached and undyed fabrics of 100% cotton and 50% cotton + 50% polyester (poly cotton) to fingerpads or other pieces of fabric. METHODS AND RESULTS: Test pieces of the fabrics were mounted on custom-made stainless steel carriers to give a surface area of 1 cm in diameter, and each piece seeded with about 10(5) cfu of Staphylococcus aureus from an overnight broth culture; the inoculum contained 5% fetal bovine serum as the soil load. Transfer from fabric to fabric was performed by direct contact using moist and dry fabrics. Transfers from fabrics to fingerpads of adult volunteers were tested using moist, dry and re-moistened pieces of the fabrics, with or without friction during the contact. Bacterial transfer from fabrics to moistened fingerpads was also studied. All the transfers were conducted under ambient conditions at an applied pressure of 0.2 kg cm(-2). After the transfer, the recipient fingerpads or fabric pieces were eluted, the eluates spread-plated, along with appropriate controls, on tryptic soy agar and the percentage transfer calculated after the incubation of the plates for 24 h at 37 degrees C. CONCLUSION: Bacterial transfer from moist donor fabrics using recipients with moisture was always higher than that to and from dry ones. Friction increased the level of transfer from fabrics to fingerpads by as much as fivefold. Bacterial transfer from poly cotton was consistently higher when compared with that from all-cotton material. SIGNIFICANCE AND IMPACT OF THE STUDY: The data generated should help in the development of better models to assess the role fabrics may play as vehicles for infectious agents. Also, the basic design of the reported methodology lends itself to work with other types of human pathogens.

Adult↗
PubMed1997

Pentastarch instead of albumin as replacement fluid for therapeutic plasma exchange. The Canadian Apheresis Group.

BACKGROUND: Human albumin is commonly used as a replacement fluid in therapeutic plasma exchange (PE). In order to determine whether Pentaspan (PES), a synthetic low molecular weight starch solution, might be an effective substitute, we compared albumin with PES in 12 patients with myasthenia gravis or Guillain-Barré syndrome. STUDY DESIGN AND METHODS: Six patients were randomly assigned to receive PES and six to receive albumin as replacement fluid during their course of PE, which consisted of two to five treatments delivered over a maximum of 10 days. All patients were hospitalized and observed closely. Blood pressures were recorded every 4 hours and daily measurements were made of hematologic, coagulation, and immunoglobulin parameters. RESULTS: Individual exchange volumes were similar in each group (37 ml/kg--range 6-62--in patients receiving albumin vs. 41 ml/kg--range 6-41--in those receiving PES). Changes in immunoglobulin levels and coagulation parameters were similar but mild, transient thrombocytopenia was observed in three subjects given PES. Total serum protein and albumin levels decreased significantly in patients replaced with PES. Clinically, PES was well tolerated. Hypotension occurred in one patient who developed septic shock due to an infected femoral catheter; in another patient, a pre-existing pleural effusion was thought to increase slightly. CONCLUSIONS: PES appears to be a safe replacement fluid for PE, but larger clinical studies are required to confirm these findings.

Adult↗
PubMed1997

Definition of life quality from a patient versus health care professional perspective.

Quality of life assessment is increasingly acknowledged as an important component in selecting optimal health interventions for persons with cardiovascular disease. We hypothesized that cardiac out-patients have the same perception of what comprises quality of life as do their health care providers. A list of items was compiled from all quality of life measures and quality of life research. Staff members, cardiac out-patients and family members were asked what they considered important to the patients' quality of life by rating the relative importance of each item on the list. The three groups differed in their ratings. Of the top ten items ranked by patients, only three items appeared on the staff top ten list, and five on the family member's list. The patients, in contrast with staff and family, chose aspects of QL that reflected the positive aspects of life. These differences were more marked in the physical, psychological, and activity domains than in the social domain. The study suggests that QL measures developed from the perspective of primary caregivers are probably invalid and therefore QL measures should be developed from a patients perspective.

Adult↗
PubMed1996

Cryosupernatant as replacement fluid for plasma exchange in thrombotic thrombocytopenic purpura. Members of the Canadian Apheresis Group.

The current established treatment of thrombotic thrombocytopenic purpura (TTP) is plasma exchange with fresh frozen plasma (FEP). With this treatment, there is a 49% response after seven exchanges and a 78% survival at 1 month. Although the exact cause of TTP is unknown, the presence of von Willebrand factor (VWF) multimers has been implicated in the disease. Accordingly, it has been suggested that cryosupernatant (plasma from which cryoprecipitate has been removed), which is relatively deficient in VWF multimers, might be an effective replacement fluid during plasma exchange. Patients from six centers were treated by plasma exchange with cryosupernatant. 18 patients who had failed a first course (average 7.7 exchanges) of plasma exchange with FFP. received a further seven exchanges with cryosupernatant. Subsequently, 40 previously untreated patients were exchanged with cryosupernatant. Of the 18 previously treated patients, 11 responded (defined as an increase in platelet count to > 150 x 10(9) /1 and no neurological events) after seven exchanges and 15 (83%) of the patients were alive at 1 month. The response rate in the 40 previously untreated patients was 75% at the end of seven exchanges and 95% of the patients were alive at 1 month. These values are significantly different (P < 0.05) from those reported in our earlier study and in other patients concurrently treated at the same centres with FFP when cryosupernatant was not available. Some patients who have failed to respond to plasma exchange with FFP replacement will respond to further exchange with cryosupernatant. Cryosupernatant replacement may be more effective as first-line treatment of TTP than FFP.

Adult↗
PubMed1996

Acute respiratory tract infection: a community-based intervention study in Malaysia.

A community-based intervention trial was conducted in Kelantan, Malaysia with the aim of reducing severe acute respiratory tract (ARI) infection in children. Interventions included health education of mothers on childhood pneumonia and training of health staff on case management. In a house-to-house survey 1382 and 1107 children less than 5 years of age in the intervention and control areas, respectively, were followed up every 2 weeks over a 62-week period. The reduction in the incidence of severe ARI cases in the intervention area was significantly greater than in the control area (P < 0.05). The ARI mortality rates were low in both the intervention and control areas ( < 0.1%). Our results indicate that with relatively inexpensive methods and simple interventions, reduction of severe ARI may be effectively achieved. This has important implications for an ARI control programme in Malaysia and other developing countries.

Acute Disease↗
PubMed1995

Late relapses in patients successfully treated for thrombotic thrombocytopenic purpura. Canadian Apheresis Group.

OBJECTIVE: To determine the incidence and timing of relapses in patients who have recovered from an acute episode of thrombotic thrombocytopenic purpura. DESIGN: Clinical follow-up for 3 to 10 years. SETTING: General community outpatient study; patients who had relapse were hospitalized. PARTICIPANTS: 63 of 72 surviving patients who had participated in a randomized study that compared plasma exchange and plasma infusion as treatments for thrombotic thrombocytopenic purpura and for whom continued clinical follow-up was obtained. OUTCOME MEASURES: Recurrence of thrombotic thrombocytopenic purpura as defined by a decrease in platelet count to less than 100 x 10(9)/L and by the onset of microangiopathic hemolytic anemia as identified by erythrocyte fragmentation in a peripheral blood film. RESULTS: 37 of the 63 patients have not had recurrence of thrombotic thrombocytopenic purpura and have remained completely well; 6 patients have not had recurrence but have developed other medical problems; 3 patients have not had recurrence but have residual neurologic defects from the original episode; and 17 patients have had one or more recurrences, occurring 7 months to 8 years after the original episode. As determined by Kaplan-Meier analysis, the projected recurrence rate after 10 years in all surviving patients is 36% (95% CI, 23% to 59%). CONCLUSIONS: More than one third of patients who survive an acute episode of thrombotic thrombocytopenic purpura will have at least one relapse during the following 10 years.

Adult↗
PubMed1995

An outbreak of acute hepatic encephalopathy due to severe aflatoxicosis in Malaysia.

In October 1988, 13 Chinese children died of acute hepatic encephalopathy in the northwestern state of Perak in peninsular Malaysia. The acuteness of the illness differed from previously reported outbreaks described in Kenya, India, and Thailand. Epidemiologic investigations determined that the children had eaten a Chinese noodle, loh see fun, hours before they died. The attack rates among those who had eaten the noodles were significantly higher than those who had not (P < 0.0001). The cases were geographically scattered in six towns in two districts along the route of distribution of the noodle supplied by one factory in Kampar town. Aflatoxins were confirmed in postmortem samples from patients. This outbreak has important public health implications for many developing countries.

Acute Disease↗
PubMed1994

Implementation of the Ottawa ankle rules.

OBJECTIVE: To assess the impact on clinical practice of implementing the Ottawa ankle rules. DESIGN: Nonrandomized, controlled trial with before-after and concurrent controls. SETTING: Emergency departments of a university (intervention) hospital and a community (control) hospital. PATIENTS: All 2342 adults seen with acute ankle injuries during 5-month periods before and after the intervention. INTERVENTION: The implementation of the Ottawa ankle rules by emergency department physicians. MAIN OUTCOME MEASURE: Proportions of patients referred for standard ankle and foot radiographic series. RESULTS: There was a relative reduction in ankle radiography by 28% at the intervention hospital but an increase by 2% at the control hospital (P < .001). Foot radiography was reduced by 14% at the intervention hospital but increased by 13% at the control hospital (P < .05). Compared with nonfracture patients who had radiography during the after period at the intervention hospital, those discharged without radiography spent less time in the emergency department (80 minutes vs 116 minutes; P < .0001), had lower estimated total medical costs for physician visits and radiography ($62 vs $173; P < .001), but did not differ in the proportion satisfied with emergency physician care (95% vs 96%) or undergoing subsequent radiography (5% vs 5%). The rules were found to have sensitivities of 1.0 (95% confidence interval [CI], 0.95 to 1.0) for detecting 74 malleolar fractures and 1.0 (95% CI, 0.82 to 1.0) for detecting 19 midfoot fractures. In the following 12 months at the intervention hospital, use of radiography did not increase. CONCLUSIONS: Implementation of the Ottawa ankle rules led to a decrease in use of ankle radiography, waiting times, and costs without patient dissatisfaction or missed fractures. Future studies should address the generalizability of these decision rules in a variety of hospital settings.

Adult↗
PubMed1994

Acute respiratory infection in Malaysian children.

A cross-sectional community-based survey was conducted to determine the prevalence of acute respiratory infection (ARI) in children below 7 years of age and to obtain baseline information for an intervention programme. A total of 6190 households comprising 38,632 persons with 12,273 children (32 per cent) below 7 years of age were surveyed. Information on socio-demographic variables, environmental sanitation, occurrence of ARI and diarrhoea, treatment seeking behaviour during episodes of those illnesses and immunizations among children were obtained. Thirty per cent of children had experienced ARI in the 2-week period prior to the interview, and 94 per cent had mild ARI, 1 per cent had moderate and 5 per cent had severe ARI. There was lack of concurrence between mother's perception of severity and that of the investigators' (Kappa coefficient = 0.083 (95 per cent CI = 0.017-0.149). Twenty-four and 39 per cent of severe and moderate ARI, respectively, were reported by mothers to be mild. There is cause for concern as these children may not receive timely and appropriate treatment. The findings from this study contribute to identification of target populations and priority areas for health education of the population. The survey has provided useful baseline data for the implementation of an intervention programme for the control of ARI in children.

Acute Disease↗
PubMed1993

Anthropometric craniofacial pattern profiles in Down syndrome.

A series of 21 anthropometric craniofacial measurements was performed on 199 individuals with Down syndrome (DS), age 6 months to 61 years. These were compared to age and sex-matched normal standards, and Z score pattern profiles were constructed. These profiles confirmed brachycephaly and reduced ear length. With increasing age, maxillary growth was reduced in comparison to mandibular growth. Clinically, this was manifested by a change in facial shape from the characteristic round face of infancy to an oval shape in later life. Stepwise forward discriminant function analysis identified a subset of three variables (ear length, maxillary arc, and upper facial depth) which could accurately classify greater than 99% of the individuals in the combined sample of affected and unaffected individuals. Of the subjects with DS, 96.8% were classified correctly. These findings demonstrate the usefulness of anthropometric craniofacial pattern profiles in defining abnormal facial dimensions in particular syndromes and documenting the changes that occur with age. The technique should facilitate syndrome recognition, identification of carriers, and comparisons between syndromes.

Adolescent↗
PubMed1993

Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation.

OBJECTIVE: To validate and refine previously derived clinical decision rules that aid the efficient use of radiography in acute ankle injuries. DESIGN: Survey prospectively administered in two stages: validation and refinement of the original rules (first stage) and validation of the refined rules (second stage). SETTING: Emergency departments of two university hospitals. PATIENTS: Convenience sample of adults with acute ankle injuries: 1032 of 1130 eligible patients in the first stage and 453 of 530 eligible patients in the second stage. MAIN OUTCOME MEASURES: Attending emergency physicians assessed each patient for standardized clinical variables and classified the need for radiography according to the original (first stage) and the refined (second stage) decision rules. The decision rules were assessed for their ability to correctly identify the criterion standard of fractures on ankle and foot radiographic series. The original decision rules were refined by univariate and recursive partitioning analyses. MAIN RESULTS: In the first stage, the original decision rules were found to have sensitivities of 1.0 (95% confidence interval [CI], 0.97 to 1.0) for detecting 121 maleolar zone fractures, and 0.98 (95% CI, 0.88 to 1.0) for detecting 49 midfoot zone fractures. For interpretation of the rules in 116 patients, kappa values were 0.56 for the ankle series rule and 0.69 for the foot series rule. Recursive partitioning of 20 predictor variables yielded refined decision rules for ankle and foot radiographic series. In the second stage, the refined rules proved to have sensitivities of 1.0 (95% CI, 0.93 to 1.0) for 50 malleolar zone fractures, and 1.0 (95% CI, 0.83 to 1.0) for 19 midfoot zone fractures. The potential reduction in radiography is estimated to be 34% for the ankle series and 30% for the foot series. The probability of fracture, if the corresponding decision rule were "negative," is estimated to be 0% (95% CI, 0% to 0.8%) in the ankle series, and 0% (95% CI, 0% to 0.4%) in the foot series. CONCLUSION: Refinement and validation have shown the Ottawa ankle rules to be 100% sensitive for fractures, to be reliable, and to have the potential to allow physicians to safely reduce the number of radiographs ordered in patients with ankle injuries by one third. Field trials will assess the feasibility of implementing these rules into clinical practice.

Adolescent↗
PubMed1992

Use of radiography in acute ankle injuries: physicians' attitudes and practice.

OBJECTIVES: To examine the efficiency of the current use of radiography in patients with acute ankle injury. To study the judgements and attitudes of experienced clinicians in their use of ankle radiography and to thereby assess the potential for improved efficiency. DESIGN: Two-stage study: retrospective chart review and prospective survey. SETTING: Emergency departments of two adult teaching hospitals and one community hospital. PARTICIPANTS: The records of 1831 adults presenting with acute blunt trauma to the ankle over 5 months were examined; another 732 patients were seen by 21 full-time emergency staff physicians over a subsequent 6-month period. MEASURES AND MAIN RESULTS: Of the 1831 patients with an ankle injury in stage 1, 94.9% had had at least one radiographic series; the yield for clinically important fractures was 12.8%. In stage 2, experienced physicians predicted the probability of fracture to be 0% or 10% in 57.8% of cases. The kappa (kappa) level for interobserver agreement in 98 patients seen independently by two physicians was 0.55 (95% confidence interval [CI] 0.39 to 0.72). The area under the receiver operating characteristic curve for physicians' predicted probability was 0.88 (95% CI 0.84 to 0.92), reflecting good discrimination between fracture and nonfracture cases. Likelihood ratios for predicted probabilities ranged from 0.08 for the 0% level to 151 for the 100% level. The physicians indicated that they would feel comfortable or very comfortable in not ordering radiography in 45.9% of cases (kappa level 0.52; 95% CI 0.34 to 0.70). CONCLUSIONS: Emergency physicians order radiography for most patients with ankle injury even though they can accurately discriminate between fracture and nonfracture cases and clearly expect most of the radiographs to give normal results. These findings suggest great potential for a more efficient use of radiography in patients with ankle injury, possibly through the use of guidelines.

Adult↗
PubMed1992

Interobserver agreement in the examination of acute ankle injury patients.

The authors' objective was to describe a method for measuring interobserver agreement and to determine the reliability of physical findings used by emergency physicians to assess ankle injury patients. A 3-month prospective survey was designed for use in the emergency departments of two university hospitals. Participants were a convenience sample of 100 adult blunt ankle injury patients. Pairs of emergency staff physicians assessed 22 standardized physical findings in each patient without knowledge of the other assessment. Agreement for each variable was measured by the kappa coefficient, the ratio of actual agreement to potential agreement beyond chance. The variables with the highest interobserver agreement and their kappa values were ability to bear weight (.83); bone tenderness at the base of the fifth metatarsal (.78), at the posterior edge of lateral malleolus (.75), and at the tip of the medial malleolus (.66); and combinations of bone tenderness (.76). Less reliable variables included soft tissue tenderness (.41) or degree of swelling (.18) of the anterior talofibular ligament, ecchymosis (.39), range of motion (.33), bone tenderness at the proximal fibula (-.01), and the anterior drawer sign (-.03). High kappa values indicate that several physical findings, including ability to bear weight and selected sites of bone tenderness, may be reliably assessed in ankle injury patients. This knowledge may give physicians more confidence in their physical examination and allow development of reliable clinical guidelines to diminish the reliance on radiography in ankle injuries.

Adult↗
PubMed1992

A study to develop clinical decision rules for the use of radiography in acute ankle injuries.

STUDY OBJECTIVE: To develop decision rules that will predict fractures in patients with ankle injuries, thereby assisting clinicians in being more selective in their use of radiography. DESIGN: Prospective survey of emergency department patients over a five-month period. SETTING: Two university hospital EDs. PARTICIPANTS: One hundred fifty-five adults in a pilot stage and 750 in the main study; all presented with acute blunt ankle injuries. INTERVENTIONS: Thirty-two standardized clinical variables were assessed and recorded on data sheets by staff emergency physicians before radiography. MEASUREMENTS: Variables were assessed for reliability by the kappa coefficient and for association with significant fracture on both ankle and foot radiographic series by univariate analysis. The data then were analyzed by logistic regression and recursive partitioning techniques to develop decision rules for predicting fractures in each radiographic series. MAIN RESULTS: All 70 significant malleolar fractures found in the 689 ankle radiographic series performed were identified among people who had pain near the malleoli and were age 55 years or more, had localized bone tenderness of the posterior edge or tip of either malleolus, or were unable to bear weight both immediately after the injury and in the ED. This rule was 100% sensitive and 40.1% specific for detecting malleolar fractures and would allow a reduction of 36.0% of ankle radiographic series ordered. Similarly, all 32 significant midfoot fractures on the 230 foot radiographic series performed were found among patients with pain in the midfoot and bone tenderness at the base of the fifth metatarsal, the cuboid, or the navicular. CONCLUSION: Highly sensitive decision rules have been developed and will now be validated; these may permit clinicians to confidently reduce the number of radiographs ordered in patients with ankle injuries.

Adult↗
PubMed1991

Comparison of plasma exchange with plasma infusion in the treatment of thrombotic thrombocytopenic purpura. Canadian Apheresis Study Group.

BACKGROUND: Thrombotic thrombocytopenic purpura is an uncommon disease with a high mortality rate even with current treatment. The cause of the syndrome and its optimal treatment are unknown. Although both plasma exchange and plasma infusion have been useful treatments, it is not clear which is superior. In this report we describe a prospective randomized trial comparing plasma exchange with plasma infusion for the treatment of thrombotic thrombocytopenic purpura. METHODS: One hundred two patients with thrombotic thrombocytopenic purpura were randomly assigned to receive either plasma exchange or plasma infusion with fresh-frozen plasma on seven of the first nine days after entry into the trial. The total volume of plasma received by patients undergoing plasma exchange was three times that received by patients undergoing plasma infusion. All the patients also received aspirin and dipyridamole. The outcomes in the two groups were compared at the end of the first treatment cycle (day 9) and after six months. RESULTS: At the end of the first treatment cycle patients receiving plasma exchange had a higher rate of response as defined by an increase in the platelet count (24 of 51 patients) than those who received plasma infusion (13 of 51, P = 0.025). Of the 51 patients treated with plasma exchange, 2 died, whereas 8 of the 51 patients who received plasma infusion died (P = 0.035). After six months the outcome in the plasma-exchange group was still superior, with a response observed in 40 of 51 patients, whereas 25 of 51 patients in the plasma-infusion group responded (P = 0.002). Eleven patients in the plasma-exchange group died, as did 19 patients in the plasma-infusion group (P = 0.036). The overall mortality was 29 percent. CONCLUSIONS: Plasma exchange is more effective than plasma infusion in the treatment of thrombotic thrombocytopenic purpura.

Adult↗