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Biomedical subjects

D S Arthur

Publications and source records attributed to D S Arthur.

11 recordsLinked to original sources

Revision rates after knee replacement in the United States.

OBJECTIVES: Each year approximately 100,000 Medicare patients undergo knee replacement surgery. Patients, referring physicians, and surgeons must consider a variety of factors when deciding if knee replacement is indicated. One factor in this decision process is the likelihood of revision knee replacement after the initial surgery. This study determined the chance that a revision knee replacement will occur and which factors were associated with revision. METHODS: Data on all primary and revision knee replacements that were performed on Medicare patients during the years 1985 through 1990 were obtained. The probability that a revision knee replacement occurred was modeled from data for all patients for whom 2 full years of follow-up data were available. Two strategies for linking revisions to a particular primary knee replacement for each patient were developed. Predictive models were developed for each linking strategy. ICD-9-CM codes were used to determine hospitalizations for primary knee replacement and revision knee replacement. RESULTS: More than 200,000 hospitalizations for primary knee replacements were performed, with fewer than 3% of them requiring revision within 2 years. The following factors increase the chance of revision within 2 years of primary knee replacement: (1) male gender, (2) younger age, (3) longer length of hospital stay for the primary knee replacement, (4) more diagnoses at the primary knee replacement hospitalization, (5) unspecified arthritis type, (6) surgical complications during the primary knee replacement hospitalization, and (7) primary knee replacement performed at an urban hospital. CONCLUSIONS: Revision knee replacement is uncommon. Demographic, clinical, and process factors were related to the probability of revision knee replacement.

Aged↗

Outcome implications for the timing of bilateral total knee arthroplasties.

Health Care Financing Administration data from 1985 to 1990 revealed 339,152 total knee arthroplasties of which 62,730 (18.6%) were bilateral procedures (simultaneous 112,922; staged 6 weeks, 4354; staged 3 months, 4524; staged 6 months, 9829; and staged 1 year 31,401). Medicare beneficiaries undergoing bilateral procedures were an average of 73 years of age; demographics revealed that among the various simultaneous and staged groups 57% to 69% were females, 90% were white, 85% to 90% had a diagnosis of osteoarthritis, and 30% to 40% were performed in rural hospitals. Between 1985 and 1990, surgical and vascular complications ranged from 2.4% to 4% and 4.1% to 6.8%, respectively, for all types of bilateral staged and simultaneous total knee arthroplasties. All differences were statistically significant. After controlling statistically for demographic variables and diagnoses, a surrogate for case mix, it was found that individuals electing simultaneous bilateral arthroplasties experienced twice the number of intensive care days than those choosing staged procedures. Days in the intensive care unit were double when done simultaneously instead of staged (0.48 versus 0.21). Nosocomial infections were similar within groups (10% versus 13%); however, wound infections were nearly half when done simultaneously (0.5% versus 1%) versus in a staged fashion. Length of stay and cost were much less for the simultaneous procedure group who were sicker as measured by the number of diagnoses. Mortality at 30 days was highest for the simultaneous procedure group (.99%) versus staged 3 or 6 months (0.30%); however, by 2 years it was close to 4% for all groups. Staging the procedure 3 to 6 months seems to offer the fewest disadvantages, is only slightly more expensive, and has the lowest mortality rate.

Age Factors↗

Comparison of recovery from anaesthesia induced in children with either propofol or thiopentone.

We studied 102 children undergoing day-case surgery, allocated randomly to receive either thiopentone 5 mg kg-1 or propofol 3 mg kg-1 i.v. at induction of anaesthesia. They then inhaled nitrous oxide and halothane in oxygen until a laryngeal mask airway could be inserted. Thereafter, halothane was substituted by isoflurane and analgesia provided by regional nerve block. Recovery from anaesthesia was assessed by the time taken to reach clinically-defined criteria and by calculation of sedation, pain and vomiting scores. In children aged less than 5 yr, only the time to spontaneous eye opening was shorter after propofol induction (P < 0.05). In children aged 5-11 yr, times of spontaneous eye opening, giving name and discharge were shorter after propofol induction (P < 0.05). These results indicate that propofol hastened early recovery in children undergoing day-case surgery, but earlier discharge occurred only in older children.

Ambulatory Surgical Procedures↗

Pierre Robin syndrome and pulmonary hypertension.

Five infants with Pierre Robin syndrome developed evidence of carbon dioxide retention and congestive cardiac failure despite measures to alleviate upper airway obstruction. Investigations included chest radiography, electrocardiography, echocardiography, and cardiac catheterization; pulmonary hypertension was diagnosed. In two cases raised main pulmonary artery pressures of 40 mm Hg and 120 mm Hg were recorded. Relief of upper airway obstruction was achieved by tracheostomy in three cases and nasopharyngeal intubation in two cases, with reversal of signs of cor pulmonale in each. Four patients progressed well with no recurrence of cardiac problems but one died suddenly one month after apparently successful management by tracheostomy.

Female↗

Reports by anaesthetists to procurators-fiscal: analysis of "anaesthetic deaths" over 10 years in four Scottish teaching hospitals.

Review of 489 "anaesthetic deaths" reported to procurators-fiscal over 10 years disclosed only 30 that were thought to justify such reporting. Most of the remainder occurred in patients so desperately ill at the time of operation that death was expected. Postmortem examinations ordered by the Crown authorities in nearly all cases were probably largely unrewarding and mostly unnecessary. The results suggest that the present regulation on reporting should be revised to focus more attention on the few deaths that occur in patients who have no apparent contraindication to anaesthesia or operation.

Adult↗

The effect of artificial ventilation on functional residual capacity and arterial oxygenation. II. Comparison of spontaneous respiration and artificial ventilation at similar arterial carbon dioxide tensions, tidal volumes and inspiratory gas flow rates.

We have compared cardiac output, gas exchange and pulmonary mechanics during spontaneous breathing and artificial ventilaton under conditions which kept PaCO2 within the normal range and maintained constant tidal volume and inspired gas flow rate. In dogs anaesthetized with pentobarbitone and ventilated with air, artificial ventilation increased VD/VT but did not reduce Q angstrom, FRC, or CL. PaO2 increased and A-aDO2 decreased during aritificial ventilation, perhaps because of a small increase in Q angstrom and a small decrease in oxygen consumption. It appears that many of the reported deleterious effects of artificial ventilation may be due to the use of other anaesthetic agents and patterns of ventilation, and to changes in PaCO2.

Anesthesia↗