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Biomedical subjects

B Davidson

Publications and source records attributed to B Davidson.

At least 109 records · Page 6Linked to original sources
PubMed1994

Biliary anastomosis after liver transplantation does not benefit from T tube splintage.

T tubes are commonly used to splint biliary anastomoses after liver transplantation. Although several advantages are claimed for this approach, there is undoubtedly some iatrogenic morbidity associated with the use of T tubes in this situation. We have evaluated 120 consecutive biliary reconstructions after liver transplant, the majority of which were unsplinted end to end bile duct anastomoses. We have shown that biliary leakage and stricture rates are not significantly affected by T tubes. We have also shown that endoscopic retrograde cholangiopancreatography and percutaneous cholangiography are reliable posttransplant methods for cholangiography and stricture dilatation. Routine T tube splintage of post-liver transplant biliary anastomoses is unjustified.

Anastomosis, Surgical↗
PubMed1994

Conjunctival oxygen tension monitoring during liver transplantation.

Conjunctival oxygen tension has been noted in animal studies to correlate with oxygen delivery. In order to assess this relationship in man, we compared the proportional changes in conjunctival oxygen tension with those in oxygen delivery that occur on the placement and release of the inferior vena caval clamps in 10 patients during orthotopic liver transplantation without veno-venous bypass. We also examined the changes in mixed venous oxygen saturation at these times. We found a statistically significant correlation between both parameters and oxygen delivery (p < 0.001). However, analysing the data on a Bland and Altman plot of difference versus mean, it is our conclusion that the variation in the data is such that neither conjunctival oxygen tension nor mixed venous oxygen saturation can be used clinically to predict the changes in oxygen delivery that occur during liver transplantation.

Blood Pressure↗
PubMed1994

A prospective randomized clinical trial of liver preservation using high-sodium versus high-potassium lactobionate/raffinose solution.

High-sodium as opposed to high-potassium lactobionate/raffinose preservation solution offers potential advantages in improving the quality of liver storage by reducing potassium-induced vasoconstriction and preventing hyperkalaemia on reperfusion. In our study we evaluated in a prospective trial (encompassing 40 consecutive cadaver donor hepatic retrievals and subsequent transplants) the efficacy of a high-sodium formulation versus the standard high-potassium solution. Quality of preservation was assessed by clinical indices of liver function in the intraoperative and early postoperative phases, including measurements of requirements for blood and blood products and potassium, circulating liver enzymes and bilirubin. Frequencies of acute rejection episodes and primary non-function were also recorded. No significant differences were evident in any of the measured parameters. Thus a sodium-based solution can be used for hepatic preservation, advancing the possibility that it may be possible to develop a single storage solution for clinical multi-organ donor operations.

Adult↗
PubMed1994

Ethical reasoning concerning the feeding of severely demented patients: an international perspective.

Structured interviews were held with 149 registered nurses in seven countries in America, Asia, Australia and Europe concerning the feeding of severely demented patients who do not accept food. The most common reasons for nurses being willing to change their decision to feed or not to feed were an order from the medical head, a request from the patient's husband and/or the staff meeting. There was a connection between the willingness to feed and the ranking of ethical principles. Nurses who were most prone to feed the patient most often gave a high rank to the ethical principle of sanctity of life, while those who primarily chose not to feed the patient gave a high rank to the ethical principle of autonomy. All nurses stressed the ethical principle of beneficence.

Adult↗
PubMed1994

Electrophysiologic effects of propofol sedation.

The scalp electroencephalogram (EEG), the long latency cognitive P300 auditory evoked response (AER), and reaction times were recorded in 10 volunteers sedated with a computer-controlled infusion of propofol to target plasma concentrations of 0.3, 0.6, 0.9, and 1.2 micrograms/mL. The observed mean +/- SE venous plasma concentrations were 0.152 +/- 0.042, 0.372 +/- 0.078, 0.679 +/- 0.104, and 1.065 +/- 0.112 micrograms/mL, respectively. Scalp EEG topographic mapping revealed that beta 1 activation was primarily frontal and central with relative sparing of the temporal lobes. The P300 response was dramatically reduced by propofol in a concentration-dependent manner, even though the subjects were conscious but clearly sedated. Mean +/- SE reaction times were increased by propofol sedation from 347 +/- 35 ms (control) to 391 +/- 48, 460 +/- 70, 549 +/- 64, and 622 +/- 120 ms at increasing mean venous plasma propofol concentrations. The mean percentage +/- SE of correct responses decreased from 98.1 +/- 2.0 (control) to 99.1 +/- 1.7, 87.4 +/- 9.2, 82.8 +/- 12.9, and 69.8 +/- 20.9 at increasing propofol concentrations. Dramatic alterations in the EEG, P300 response, and reaction times were observed, especially with the higher plasma concentrations which produced conscious sedation.

Adult↗
PubMed1994

Studies on the presence of endotoxin activity and inflammatory products (leukotrienes) in cases of experimentally induced heartwater in sheep.

The presence of endotoxin was examined in seven sheep with experimentally induced heartwater. Elevations in endotoxin levels were recorded in one sampling in three of the seven sheep during the acute stage of the disease. The elevations in endotoxin levels were of short duration and decreased in the 24-h follow-up samples. There was no elevation of leukotrienes (B4, C4 and D4) in the blood, or the thoracic or pericardial fluid of any of the sheep.

Animals↗
PubMed1994

Postural control in pilots and candidates for flight training.

Postural control may reflect the pilot's ability to deal successfully with the stresses of spatial orientation. In this study, we hypothesized that fighter pilots would have better performance on the "tetra-axiametric posture test" than would helicopter pilots (less rigorously selected) and candidates for flight training. We tested 28 fighter pilots, 23 helicopter pilots and 43 candidates by tetra-axiametric posturography. Fighter pilots were found on the level position to have significantly more compensatory anterior-posterior sway (moving anterior-posterior rather than laterally, p = 0.02) and required less movements to maintain balance (p = 0.02) than did candidates. Helicopter pilots had intermediate values. In stressed positions, fighter pilots demonstrated relatively more slow movements (p = 0.018) than did the candidates, which may be related to increased labyrinth control. In the stressed positions, helicopter pilots had postural profiles similar to the candidates. We conclude that there are significant differences in postural control as tested by tetraaxiametric posturography between fighter pilots, helicopter pilots, and candidates for flight training. This could be due to either innate ability, which could be used in the selection process, or to training. A prospective study is planned in order to determine if posturography can predict a candidate's ability to complete flight training.

Adolescent↗
PubMed1994

Low molecular weight heparin: a critical analysis of clinical trials.

LMWHs are an important new class of antithrombotic agents. They differ from UFH in having relatively more anti-Xa activity, greater bioavailability at low doses, longer half-life, and more predictable anticoagulant response when administered in fixed doses. These properties allow LMWHs to be administered QD or at most BID and without laboratory monitoring. The incidence of heparin-induced thrombocytopenia also appears to be lower with an LMWH than with heparin. Given their favorable pharmacological profile, it was of interest to critically appraise clinical trials of thromboprophylaxis and treatment with these new agents. In orthopedic trials, it was noted that LMWH provided safe and effective thromboprophylaxis for patients undergoing major orthopedic surgery of the lower limb. In those having hip arthroplasty, LMWH was as effective as low-intensity warfarin therapy, but its use was associated with more wound hematomas. In those having total knee arthroplasty, LMWH was more effective than warfarin and did not increase bleeding. However, the prevalence of DVTs complicating this procedure as well as acute hip fracture remains unacceptably high, and additional studies of LMWH in combination with other prophylactic methods, such as external pneumatic compression, are needed. Only one adequately designed trial found less bleeding resulted from LMWH prophylaxis administered at an equivalent antithrombotic dose to UFH. In general medical patients, LMWH appeared to be as effective as UFH and had the advantages of less frequent injections and fewer injection site hematomas. In general surgical patients, there was a lower risk of thromboembolism but a trend toward an increase in bleeding events. Subjects with strokes and spinal cord injuries benefited from fewer thrombotic events, and the latter had fewer bleeding complications. Other potential indications for LMWH, such as cardiopulmonary bypass, hemodialysis, and preservation of graft patency, are presently under study. Perhaps the most impressive benefits of LMWH will be realized when it is used for the treatment of venous thromboembolism. The meta-analysis presented in this review showed a trend toward greater efficacy with LMWH and fewer major bleeding events in comparison with adjusted-dose intravenous UFH. Also, during the months following the thrombotic event, there was significantly less mortality in patients receiving LMWH. A further advantage was the subcutaneous route of administration and lack of requirement for laboratory monitoring. Additional treatment trials are presently in progress and may establish LMWH as the treatment of choice for patients with thromboembolic disorders.

Animals↗
PubMed1993

An international perspective of active euthanasia: attitudes of nurses in seven countries.

This exploratory study examines the ethical justification that cancer care and dementia care nurses gave for active voluntary euthanasia. A convenient sample of 319 nurses working in seven countries was interviewed using a structured interview guide. The great majority of the nurses could not ethically justify active voluntary euthanasia. Even if the law changed, only 96 of the total sample viewed active voluntary euthanasia as ethical. For those nurses who could ethically justify active voluntary euthanasia, the majority did so because of the patients' suffering.

Adult↗
PubMed1993

Duplex ultrasonography for the detection of deep vein thrombi after total hip or knee arthroplasty.

The usefulness of real-time duplex ultrasonography (DU) as a screening test for deep vein thrombosis (DVT) in high-risk patients remains uncertain. To determine the sensitivity and specificity of DU for the detection of DVT, the authors prospectively studied 178 consecutive patients after total hip (n = 113) or total knee (n = 66) arthroplasty. The deep veins from the inguinal ligament to the ankle were examined first by continuous wave and then by pulsed Doppler signals as needed with real-time gray-scale ultrasound imaging using the criteria of vein noncompressibility to define DVT. Ascending contrast venography was performed within twelve hours after DU studies. Venograms and DU were interpreted independently. DU was attempted on 177 lower extremities (2 patients refused) but was judged adequate for interpretation for only 145 (82%). Venography could not be performed for 28 lower extremities and was technically inadequate for 8 studies. The primary analysis included 119 examinations for which adequate DU and ascending venograms were interpreted. DU was positive in 17 of 27 lower extremities with DVT (23 calf, 4 proximal) diagnosed by venography (sensitivity = .63; 95% confidence interval [CI] = .42 to .81), and DU was negative in 85 of 92 lower extremities with normal venograms (specificity = .92; 95% CI = .85 to .97). A secondary analysis of 81 prospectively collected anatomically complete DU studies demonstrated a sensitivity of .80 (95% CI = .56 to .94) and a specificity of .90 (95% CI = .80 to .96).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Prognostic significance of anastomotic recurrence from colorectal adenocarcinoma.

A retrospective analysis of the prognostic significance of anastomotic recurrence in 50 patients with colorectal adenocarcinoma was conducted from 1970 to 1987. All primary cancers were located above 10 cm from the anal verge. Forty anastomotic recurrences (80 percent) followed resection of sigmoid or proximal rectal tumors. The overall disease-free interval was 13 months, with 90 percent of recurrences diagnosed within 24 months of the primary resection. Forty-five recurrences (90 percent) were associated with synchronous or metachronous metastases. Overall median survival following the recurrence was 16 months--37 months if the anastomosis was the only recurrence site. Of five patients alive without evidence of disease, all were asymptomatic, and recurrence was confined to the anastomosis. In conclusion, anastomotic recurrence following resection of colorectal adenocarcinoma frequently heralds disseminated disease but can be potentially resected for cure if it is the only site in an otherwise asymptomatic patient.

Adenocarcinoma↗
PubMed1992

Value of exfoliative cytology for investigating bile duct strictures.

The cause of a biliary tract stricture may be difficult to determine radiologically. Exfoliative biliary cytology was evaluated in 62 patients (median age 65 years, range 30-94) with biliary tract strictures presenting to the Hepatobiliary Unit between January 1984 and December 1989. Bile samples were taken during endoscopic retrograde cholangiopancreatography (ERCP) in 42 patients, percutaneous cholangiography in 14, and both in six. The site of stricturing was upper third of the bile duct in 43% (n = 27), middle third in 10% (n = six), and lower third in 47% (n = 29). Of the 47 patients with radiological appearances of a malignant stricture, 22 (47%) had histological confirmation by biopsy either under computed tomography guidance, at endoscopy, at operation, or at necropsy. Fourteen of the 47 patients had positive cytology (30%). In seven patients cytology alone established the presence of malignancy (15%) and in the other seven positive cytology was confirmed by histology. The addition of cytology to tissue biopsy therefore allowed malignancy to be confirmed in 29 of the 47 patients (62%). None of the 15 patients subsequently shown to have benign disease had positive cytology. Sensitivity of the technique was 30% and specificity 100%. Samples for exfoliative cytology are simple to obtain, the results are highly specific and should be a routine part of the investigation of biliary strictures.

Adult↗
PubMed1992

A prospective controlled study comparing brush and bile exfoliative cytology for diagnosing bile duct strictures.

Imaging of biliary strictures may suggest malignancy but cytology can provide a tissue diagnosis. The aim of this study is to compare the diagnostic value of brush cytology and bile cytology. Thirty two patients (20 males, 12 females, median age 66 years, range 31-84) with biliary strictures at endoscopic retrograde cholangio pancreatography (24) or percutaneous transhepatic cholangiography (8) had bile cytology and brush cytology. Brushings were taken using a modified Geenan cytology brush (6 Fr gauge, Wilson Cook) passed alongside a guide wire placed through the stricture. Bile was aspirated after insertion of an internal/external catheter or an endoprosthesis. Bile and brushings were examined by one experienced cytologist (AD) and was reported as positive or negative for malignant cells. Twenty nine patients had malignant strictures. Sixteen were confirmed by histology and 13 had malignancy suggested by clinical follow up. Three patients had resection of histologically benign strictures. The overall sensitivity of brush cytology (17 of 29 positive, 59%) was significantly greater than bile cytology (seven of 29 positive, 24%) (p < 0.01) as was the diagnostic accuracy (63 v 31%, p < 0.01). None of the patients had positive bile cytology with negative brush cytology. There were no procedure related complications and the average sampling time once the guide wire had been inserted was less than five minutes. It is concluded that brush cytology is more sensitive than bile cytology and with the technique described is safe and rapid.

Adult↗
PubMed1992

The effect of the illness episode approach on Medicare beneficiaries' health insurance decisions.

This article reports on a quasi-experimental test of the Illness Episode Approach (IEA), a new approach to providing Medicare beneficiaries with information about the financial consequences of alternative health care coverage decisions. Beneficiaries were randomly assigned to free, three-hour workshops, half using materials developed through application of the IEA, half using traditional comparative information on insurance options. Analysis of data collected before and after the workshops indicates that participants in the Illness Episode sessions were more likely to drop duplicative coverage, to spend less on premiums, and to report that their decisions to change coverage had met their expectations. The entire sample of workshop participants showed significant increases in knowledge of Medicare and their own insurance, as well as improved satisfaction with the cost of their health care coverage.

Aged↗