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Biomedical subjects

R A Browne

Publications and source records attributed to R A Browne.

At least 19 recordsLinked to original sources

Infectious diseases and the anaesthetist.

The methods of dealing with various items of anaesthetic equipment in order to assure a fresh supply for each patient have been discussed. These consist of using disposable items, steam sterilization, disinfection by both chemical methods and pasteurization and the use of ethylene oxide sterilization. The use of disposable bacterial and viral filtres to protect ventilators and soda lime cannisters is discussed. These can then be sterilized by ethylene oxide at less frequent intervals, i.e., weekly. Protection of the anaesthetists' skin from contact with body fluids by the use of barrier methods are stressed. Methods to avoid penetration of the skin by needlestick and sharp objects are discussed. The increasing number of persons being treated for opportunistic infections makes it likely that anaesthetists will encounter increasing numbers of patients infected with HIV. The more common infections encountered in the operating room in North America have been included, with methods of avoiding possible infection from them. Constant vigilance and the use of universal precautions when caring for all patients is therefore required by the anaesthetist in the operating room in order to avoid contacting infection from patients.

Acquired Immunodeficiency Syndrome

Hepatitis B virus antibody prevalence in anaesthetists.

The prevalence of antibodies to hepatitis B virus (anti HBs or anti HBc) was 16.9 per cent in a group of anaesthetists, compared to 3.7 per cent in volunteer blood donors and 5.6 per cent of patients without hepatic infections. Professional risk factors such as treating a hepatitis B patient or working in a hospital laboratory, haemodialysis, an intensive care unit, or in oncology, did not correlate with antibody prevalence. Personal risk factors such as a history of a family member with hepatitis, or of receiving blood transfusion in the past were also not associated. A greater number of anaesthetists with a history of hepatitis in the past had antibodies, than those with no history (p less than 0.05). The country of origin may have been a contributing factor to antibody prevalence as highest positivity rates were found in subjects from Asia, Africa and Eastern Europe. One of 31 (3.2 per cent) seronegative subjects seroconverted over a four-year period. Results of testing in 1978 and 1982 revealed that 37 per cent of immune subjects possessed only anti HBc and at least one person positive for both markers on the first occasion was only anti HBc positive later. Laboratory testing, risk factors, and immunization for HBV should be examined in greater detail in larger populations of health care workers.

Adult

Viral hepatitis and the anaesthetist.

Viral hepatitis is a constant hazard to all operating room personnel. The anaesthetist should avoid contact with patients' blood and saliva as much as is possible. Hepatitis A (HAV) is spread mainly by faecal/oral contact. Carriers are almost non-existent in this disease and the main importance to the anaesthetist is that he may contact a patient who is acutely infected or one who is incubating HAV. Diagnosis of postoperative hepatic dysfunction may then be a problem. Prophylaxis with Gamma globulin is also stressed. Hepatitis B (HBV) and Non-A Non-B hepatitis (NANB) have a high incidence of carriage, and are spread mainly by blood contact. The groups of patients whom the anaesthetist should especially be aware of are reviewed, as is prophylaxis using Hepatitis B Immune Globulin and the recently introduced Hepatitis B vaccine. NANB continues to be a diagnostic problem, its diagnosis being mainly by exclusion of other causes of viral hepatitis. It appears to be responsible for more than 90 per cent of cases of posttransfusion hepatitis and more than one virus may be involved.

Anesthesiology

Right to left shunt measurement in patients suspect for pulmonary embolism.

31 patients suspect for acute pulmonary emboli were studied by measuring arterial PO2 (room air) and right to left shunt (100% oxygen breathing) to determine if measurement of the right to left shunt aided in the diagnosis of pulmonary embolism. Ventilation/perfusion or serial perfusion lung scans were performed on each patient. All patients exhibited arterial hypoxemia (PaO2 less than or equal to 80) and 27 had a shunt greater than 7%. The shunt was 15.1 +/- 3.6% in 9 patients with lung scans highly suggestive of emboli. 20 patients with lung scans of low probability for emboli had significantly less shunting averaging 10.9 +/- 3.7%. 5 patients of the latter group had shunts averaging 15.2 +/- 3.8% attributable to occult pneumonia not initially apparent. An increased right to left shunt fraction is not diagnostic of pulmonary emboli, but a normal one makes the diagnosis unlikely.

Adult

Studies on the epidemiology of antibiotic-associated Clostridium difficile colitis.

Vancomycin protects hamsters from the development of Clostridium difficile colitis after treatment with clindamycin, and vancomycin is useful in treatment of humans with the disease. Relapses have occurred in both hamsters and humans when vancomycin is discontinued. Vancomycin appears to enhance susceptibility to colonization with C. difficile by eliminating competing intestinal organisms. The nature of these organisms is not known, but various tools are now available to aid in identifying them. Cancer chemotherapeutic agents should be added to the list of factors such as surgery and antibiotics that may predispose to emergence of C. difficile. The number of organisms required for colonization of antibiotic-treated hamsters is low and cross-infection seems to play a role in the disease in hamster colonies. The organism can be detected on surfaces in rooms of patients with the disease, and on the hands of personnel caring for them. Outbreaks of the disease have been recognized. Our results suggest isolation precautions should be used to prevent spread of the organism from patients with the disease to others being treated with antibiotics.

Animals

Knotting of an epidural catheter: a case report.

Difficulty with removal of an epidural catheter is described due to formation of a knot near the end of the catheter. It is stressed that in the lumbar area an epidural catheter should never be inserted more than 5 cm into the epidural space, as curling with knot formation may occur. Removal may be attempted by pulling on the catheter if testing of a similar catheter indicates that it will withstand the tension. The patient and the spouse should be kept informed and involved in the decision-making for medico-legal reasons.

Adult

Clindamycin-induced colitis.

The hamster model of enterocolitis after the administration of clindamycin was used to study various drugs used in treatment of the disease in humans. Current evidence strongly suggests toxigenic, clindamycin-resistant Clostridium difficile is a cause of the disease in hamster and man. This organism is susceptible to vancomycin and metronidazole, and the disease could be prevented in the hamster so long as the antibiotics were given orally. A fatal colitis almost invariably ensued once they were discontinued. Administration of cholestyramine significantly prolonged survival of hamsters, but did not pervent death or colitis. Corticosteroids or atropine-diphenoxylate (Lomotil) did not alter the disease. The hamster model may be useful in studying other kinds of treatment of this disease.

Animals

Variation in the disposition of morphine after i.m. administration in surgical patients.

The disposition of morphine when administered by i.m. injection was studied in 36 patients receiving morphine as part of premedication before general anaesthesia, and in five patients who received morphine as a postoperative analgesic after median sternotomy for coronary artery surgery (PCA group). Maximum plasma concentration of morphine (CP max) was 75.3 +/- 6.0 (mean elimination rate constant (k) 4.85 X 10(-3) min-1 and half-life (T1/2) = 143 min for the preanaesthetic group. The corresponding values for PCA group were CPmax = 58.0 +/- 18.0 ng ml-1 (range 30--130 ng ml-1), k = 5.63 X 10(-3) min-1 and T 1/2 = 123 min. Analysis of variance showed no differences between the groups. Within the preanaesthetic group, there was a significant difference in k between males (k = 4.01 X 10(-3) min-1) and females (6.30 X 10(-3) min-1, P less than 0.01). The corresponding T 1/2 for males was 173 min; and 110 min for females. The variation in the disposition of morphine is thought to be the result of variations in resting muscle blood flow and inadvertent injection into adipose tissue. There were no significant differences between males and females in the preanaesthetic group with respect to age, Cpmax or time from injection to Cpmax.

Adult

Clindamycin-induced enterocolitis in hamsters.

A lethal enterocolitis was induced in hamsters by oral or parenteral administration of clindamycin in amounts comparable to those used in treatment of humans. The intestinal lesions were characterized histologically as an acute inflammatory reaction with pseudomembrane formation and resembled the lesions seen in humans with antibiotic-induced colitis. Results of quantitative stool cultures showed the numbers of Peptostreptococcus and Corynebacterium decreased in animals with colitis after challenge with 100 mg of clindamycin/kg, while numbers of Escherichia coli, Streptococcus faecalis, and clindamycin-resistant Clostridium sordellii and Clostridium difficile increased. Bacteria were not seen within the intestinal lesions. Viruses were not isolated from hamsters with colitis. Although the pathogenesis of this syndrome is not completely established, the evidence is consistent with the hypothesis that the disease is caused by clostridial toxins and that the production of these toxins by organisms within the intestines is enhanced by the effects of clindamycin upon the bowel flora.

Administration, Oral

The use of intrathecal phenol for muscle spasms in multiple sclerosis. A description of two cases.

Two cases of multiple sclerosis are described, in both of whom the disease started in yound adult life. This disability gradually progressed to the stage of paraplegia-in-flexion in which the lower limbs were fixed in adduction-and-flexion. Both patients developed painful muscle spasms which made life intolerable. These patients were treated by intrathecal phenol in glycerine in an effort to convert this spastic paralysis into a flaccid paralysis. The three advantages sought were: 1. To relieve the muscle spasms so that the patient could sit in a wheelchair and propel herself. 2. To relieve the pain of the spasms. 3. To allow access to the perineum for proper hygienic care of bladder and bowel function. The first patient obtained an excellent result (Figures 1, 2, 3) but blocks had to be repeated after approximately five months. The second patient after the block developed a good result in the right leg, but still had mild, but painless spasms in the muscles of the left leg (Figures 4 and 5). However, she was able to use a wheelchair and was discharged to a chronic hospital where she died of bulbar paralysis six months later. Intrathecal phenol thus appears to be a useful method for relieving muscle spasms and pain in the lower extremities in advanced cases of multiple sclerosis.

Adult