Pulse oximetry in a cohort study of sickle cell disease.

Oxygen saturation was determined by pulse oximetry in a representative sample of Jamaican patients with steady-state sickle cell disease in a cohort study from birth. There were 220 with homozygous sickle cell (SS) disease and 142 with sickle cell-haemoglobin C (SC) disease aged 9-18 years, and 122 with a normal haemoglobin (AA) genotype aged 15-18 years. Pulse oximetry (SpO2) values were lower in SS disease (mean [95% confidence interval], 92.5 [92.0-93.0]) than in SC disease (96.7[96.5-96.9]) or AA controls (97.1 [96.8-97.3]). Inhalation of 100% oxygen in SS patients with O2 saturations below 90% consistently increased saturation to 99-100%. In SS disease, SpO2 correlated positively with haemoglobin and fetal haemoglobin and negatively with reticulocyte counts but not with MCHC, MCV or bilirubin level. Mean SpO2 in SS subjects with a normal alpha globin gene complement (mean [SD], 91.7 [3.9]%) was lower than in heterozygotes (93.4 [4.0]%) or homozygotes (96.1 [3.0]%) for alpha+ thalassaemia, the effects of alpha-thalassaemia not being explained by differences in haemoglobin or MCHC. In SS disease, SpO2 levels were not associated with age (within this age range), sex, number of sick clinic visits or number of hospital admissions. Higher SpO2 levels were associated with greater height and weight, more frequent painful crises and less frequent acute chest syndrome, but these associations were not significant after adjustment for haemoglobin level. Desaturation is common in steady-state SS disease and knowledge of the individual's steady-state value may be important in the interpreting low values during acute complications.

Adolescent blood pressure in a cohort study of sickle cell disease.

BACKGROUND: Previous studies on low blood pressure in patients with homozygous sickle cell (SS) disease have sought new hypotheses on the mechanism of low blood pressure but have not analyzed the role of known determinants such as weight. METHODS: Blood pressure has been measured by an automated oscillometric method in 220 patients with SS disease, 144 with sickle cell-hemoglobin C disease (both groups aged, 9.5 to 18.5 years) and 122 control subjects with a normal hemoglobin genotype (aged 16.0 to 18.5 years) participating in a cohort study from birth. RESULTS: Significant age-related increases in systolic and mean arterial pressure occurred in sickle cell-hemoglobin C disease but not in SS disease. Further analyses were confined to a subgroup of 51 patients with SS, 41 patients with sickle cell-hemoglobin C, and 97 subjects with normal hemoglobin, aged 16.0 to 18.5 years in whom simultaneous measurements of height, weight, arm circumference, and hematologic test results were also available. Crude analyses showed significantly lower systolic, diastolic, and mean arterial pressure in SS disease compared with control subjects with normal hemoglobin, but further analysis showed the systolic difference to be confined to males and all differences disappeared after adjustment for weight. No differences occurred in sickle cell-hemoglobin C disease. CONCLUSIONS: These results suggest that the lower blood pressure in SS disease is attributable to low weight and that no further mechanisms need be postulated.

A proposed protocol and case report of the anaesthetic management of an HIV-positive patient.

This report describes the anaesthetic management of an HIV-positive patient and proposes a protocol for the management that is suitable for the present working conditions in Jamaica.

A proposed protocol and case report of the anaesthetic management of an HIV-positive patient

This report describes the anaesthetic management of an HIV-positive patient and proposes a protocol for the management that is suitable for the present working conditions in Jamaica

Should air-oxygen replace nitrous oxide-oxygen in general anaesthesia?

The use of compressed air-oxygen mixtures to replace nitrous oxide-oxygen in general anaesthesia was investigated in 378 patients. There were neither prolongations of recovery time nor instances of awareness under anaesthesia. The cost of general anaesthesia using compressed air-oxygen was about half that for nitrous oxide-oxygen mixtures.

A comparison of atracurium and alcuronium during halothane anaesthesia by measurement of the train-of-four response of the adductor pollicis muscle and clinical observation.

Atracurium and alcuronium have been compared during halothane anaesthesia, by measurement of the mechanical response of the adductor pollicis muscles to train-of-four stimulation and by clinical observation. Atracurium appeared significantly shorter-acting than alcuronium. However, results suggested that the action of alcuronium may not be of "medium duration". A comparison of three indices of muscle twitch response to the train-of-four nerve stimulation, seemed to indicate that the D'/D ratio gave the best overall index of neuromuscular blockade in this study.

The response of canine intracranial pressure to systemic hypotension induced with nitroglycerine.

Changes in intracranial pressure were studied in 18 greyhounds in relation to decreases in systemic arterial pressure produced by nitroglycerine. At normal values of i.c.p. (less than 12 mm Hg) GTN produced an increase in i.c.p. of 3.1 (+/- 0.6) mm Hg (mean +/- SEM). Under conditions of increased i.c.p. (12 + mm Hg) small decreases in mean arterial pressure (m.a.p.) (less than 25% control) were associated with an increase of 4.7 (+/- 0.5) mm Hg, whereas larger decreases in m.a.p. (greater than 25% control) were associated with a decrease of 3.2 (+/- 0.9) mm Hg in i.c.p. In 11 of 19 observations in which a decrease in intracranial pressure had occurred in association with systemic hypotension there was a rebound increase in i.c.p. as m.a.p. was restored. It is suggested that i.c.p. be decreased before this drug is used to produce hypotension during neurosurgery.

Insignificance of colonic bacteria in the sputum of patients in a new ICU.

Over a 12-month period, 27% of patients in a new ICU grew bacterial pathogens from sputum or tracheal cultures. The commonest isolates were Pseudomonas aeruginosa and Klebsiella species. Endotracheal intubation, the length of time intubated, and antimicrobial therapy all predisposed to the isolation of organisms from sputum. No patient developed a gram-negative pneumonia, and there was no case of septicemia associated with a positive sputum culture. The presence of epithelial or pus cells in sputum was unrelated to the culture results. It was concluded that the growth of colonic bacteria from sputum or tracheal aspirates was of little prognostic or clinical significance. No significant common environmental site or cross-infection pathway was identified: sinks were contaminated by patients rather than vice versa. Most sputum isolates were probably endogenous in origin.

General anaesthesia in sickle-cell disease.

General anaesthesia was administered on 284 occasions to 200 patients with sickle-cell disease at one hospital during July 1958 to June 1978. No intraoperative but six postoperative deaths occurred. The management of anaesthesia may have contributed to two of the postoperative deaths. Clinically uneventful anaesthesia did not appear to provoke severe sickling crises or to be responsible for mortality, but a contribution to postoperative morbidity could not be excluded. A simple, careful anaesthetic technique and selective but not routine blood transfusion appears to be associated with minimal anaesthetic morbidity and mortality in patients with sickle-cell disease.

A method for comparing endotracheal cuffs. A controlled study of tracheal trauma in dogs.

Damage to the trachea produced in dogs by large and small residual volume cuffs during 6 h of IPPV was compared using a specially designed endotracheal tube. The cuffs under evaluation were adjusted to exert similar average pressures on the tracheal wall, so that many of the variables believed responsible for tracheal injury were controlled. The true compliance of the cuff was measured with the tube inside and outside the trachea of the anaesthetized dogs. The maximum estimated pressure transmitted to the tracheal wall, derived from these compliance curves, was found to equal the peak airway pressure in the presence of a small air leak past each cuff. At various tracheal wall pressures there were only very minor differences in tracheal damage between the large and small residual volume cuffs tested.

Cardiovascular effects of isoflurane and halothane during controlled ventilation in older patients.

Isoflurane or halothane was administered at two different inspired concentrations to 21 surgical patients whose average age was 62 years. Most were in physical status (ASA) II or III. Patients were premedicated with diazepam and atropine, anesthesia was induced with thiopental, and tracheal intubation was facilitated with succinylcholine. Respiration was controlled manually or with a ventilator. Anesthesia was maintained with 60 percent N2O and halothane 1 percent, then 0.5 percent, or with N2O-isoflurane 1.2 percent, then 0.6 percent in O2. Variations in the cardiovascular responses among patients given the same anesthetic were as great as the variation in responses between anesthetics. Both produced similar decreases in arterial pressure, cardiac output, and stroke volume. Changes in pulse rate were minimal, and total peripheral resistance changes quite variable, for both drugs. Both halothane and isoflurane appear satisfactory for inhalation anesthesia in the elderly.