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Biomedical subjects

P R Fletcher

Publications and source records attributed to P R Fletcher.

At least 19 recordsLinked to original sources

Chemical burns as assault injuries in Jamaica.

A three-fold greater incidence of chemical burn injuries in Jamaican hospitals, compared to burn centres in other industrial countries, underscores the problem of the use of common chemicals for assault weapons in this country. With the increased availability of guns for personal use, many Jamaicans learned the value of carrying household chemicals such as sulphuric acid from batteries or sodium hydroxide obtained from cleaning supplies. Chemicals carried in a container, such as one might carry mace, afforded a means of defence among the lower socioeconomic groups who could not afford handguns. This use of dangerous chemicals for defensive weapons has extended to the use of chemicals for assault. The pattern of chemical injury differs significantly from most reports in the literature in both prevalence and aetiology. This review was prepared to examine these injuries with a view to planning strategies for prevention.

Adult

Primary aortoenteric fistula.

One hundred and thirty-eight patients with abdominal aortic aneurysms were treated by aneurysmorrhaphy over an eleven-year period. Six patients, all male and aged 60-74 years, were found to have developed primary aortoenteric fistulae. Four patients presented with bleeding into the gastrointestinal tract in association with a tender abdominal swelling. In the other two cases, the aneurysm was discovered at emergency laparotomy for gastrointestinal haemorrhage. The presence of the fistula was confirmed at operation in five patients and at autopsy in one. Two patients died, one from a massive gastrointestinal haemorrhage prior to surgery, the other from sepsis complicated by Adult Respiratory Distress Syndrome and renal failure following operation.

Aged

Benign colovesical fistulae.

Two successfully treated cases of benign colovesical fistula are presented. The condition should be suspected whenever patients with colorectal disease develop urinary symptoms. Flexible colonoscopy and a lateral abdominal X-ray should be the initial investigations; but barium enema, cystoscopy and, rarely, CT scan may be necessary to confirm the presence of a colovesical fistula. Patients should be managed conservatively during the acute phase, and then be treated definitively by a single-stage bowel resection. Simple closure or resection and closure is used for the bladder-defect.

Aged

Colo-mucosal proctectomy with ileo-anal anastomosis. The Jamaican experience.

A total colectomy and a mucosal proctectomy with ileo-anal anastomosis (c-mp-iaa) effectively removes all debilitating, potentially malignant colonic mucosa. Preservation of the anorectal sphincter predictably results in good to excellent anal continence with a low mortality and acceptable morbidity. Since 1983 at the University Hospital of the West Indies (U.H.W.I.), Jamaica, five (5) patients have undergone c-mp-iaa for colonic mucosal disease. All have good to excellent anal continence with an average of 2-6 continent, formed stools per day. There were no operative deaths. The five (5) cases are described and a plea is made for the earlier use of this definitive surgical procedure where indicated.

Adolescent

Appendicectomy at the University Hospital of the West Indies (1984-1988). A retrospective review.

The pathological records of appendicectomy specimens from patients with suspected acute appendicitis at the University Hospital of the West Indies during the 5-year period 1984-1988 were studied. The numbers of cases, their ages, sex and seasonal incidence were similar to those of other studies. The overall false positive diagnosis rate was 25% (16% in males, 38% in females). The main diagnostic difficulty was in young females in whom surgery for suspected appendicitis often proved unnecessary.

Acute Disease

Spontaneous rupture of the normal colon.

A case of spontaneous rupture of the colon in a previously asymptomatic patient is herein reported. At laparotomy, apart from the tear in the sigmoid colon, no other pathological problem was present. An awareness of the existence of this condition will lead to early diagnosis and management with improved morbidity and mortality.

Colon

Fine needle aspiration biopsy in the diagnosis of breast cancer.

A prospective study of 176 Fine Needle Aspiration Biopsies (FNAB) in 172 patients was carried out to assess the accuracy of FNAB in diagnosing breast cancer at the University Hospital of the West Indies. The results showed 99 per cent and 97 per cent accuracy and sensitivity rates, respectively. There were no false positives and a one per cent false negative rate. FNAB provides a rapid, safe and cheap method of accurately diagnosing breast cancer.

Biopsy, Needle

Ruptured rectal prolapse.

Rectal prolapse is not a common surgical disorder. The complication reported here, of evisceration of small bowel through a prolapsed rectum, is extremely rare and is the first case reported in the West Indies. Some of the features of rectal prolapse are described, and the surgical management of this particular complication is discussed.

Aged

Frequency dependence of dead space during high-frequency ventilation in rhesus monkeys.

A rotary valve ventilator, designed to allow the direct measurement of expired gas volume and composition, was used to maintain gas exchange in anesthetized, paralyzed, rhesus monkey at ventilatory frequencies up to 20 Hz. A total of five studies were carried out on three animals. Determinations of the minute ventilation required to maintain a normal steady-state PCO2, together with the FECO2 and arterial PO2, PCO2, and pH, were made at a number of frequencies. The results so obtained were used to calculate the Bohr (physiological) dead space. Dead space remained approximately constant at close to the value determined during spontaneous ventilation for each individual animal in the range of ventilatory frequencies from below 1 to around 5 Hz, but decreased somewhat with increasing frequency above 5 Hz. The calculated physiological dead space at 15 Hz was about 70% of the value at normal respiratory frequencies. These findings in primates, obtained using a ventilator system which allows very accurate determinations of expired gas volume and content, when compared with those from our previous studies in rabbits and dogs, provide further evidence that the relationship between efficiency of gas exchange and ventilatory frequency during HFV is highly species-specific.

Animals

Effective dead space of differently shaped airways during high-frequency ventilation of a CO2-producing lung model.

A simple lung model is described which simulates the mechanical properties and CO2 production of the lungs of a small animal, and which can be used with high-frequency ventilators. The model was ventilated by a rotary-valve ventilator and the system was used to determine the increment in 'physiological' (Bohr) dead space produced at various ventilatory frequencies between 0.5 and 15 Hz by the insertion of various additional volumes and configurations of 'anatomical' dead space in its 'upper airway'. It was found that the insertion of a straight tube with an internal diameter similar to that of the ventilator outlet tube produced an increment in 'physiological' dead space that remained commensurate with the volume of the added tube at all combinations of the tube volume and ventilatory frequency. The insertion of similar volumes of dead space in the form of tubes with smoothly expanded central portions produced increments in 'physiological' dead space which were commensurate with the volume of the added tube only at the lowest frequencies, and actually became negative at higher frequencies and volumes. These findings provide further evidence that the volume and configuration of the external portion of a high-frequency ventilator system may be of at least as much importance in determining its efficiency as is the lung structure of the animal or patient being ventilated.

Animals

Frequency dependence of dead space during high-frequency ventilation in dogs.

A rotary valve ventilator, designed to allow the direct measurement of expired gas volume and composition, was used to maintain gas exchange in anesthetized, paralyzed, mongrel dogs at ventilatory frequencies up to 20 Hz. A total of eleven studies were carried out on four animals. Determinations of the minute ventilation required to maintain a normal steady-state PCO2, together with the FECO2 and arterial PO2, PCO2, and pH, were made at a number of frequencies. The results so obtained were used to calculate the Bohr (physiological) dead space. Dead space remained approximately constant at close to the value measured during spontaneous ventilation for each individual dog in the range of ventilatory frequencies from below 1 to around 5 Hz, but decreased with increasing frequency above 5 Hz. The calculated physiological dead space at 15 Hz was about half of the value at normal respiratory frequencies. These findings in dogs, obtained using a ventilator system which allows very accurate determinations of expired gas volume and content, are consistent with published results for this species from other laboratories. They contrast with our earlier findings in rabbits that dead space remains constant with increasing frequency, suggesting that the effects of high-frequency ventilation on CO2 transport are species-dependent.

Animals