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Biomedical subjects

D S Macpherson

Publications and source records attributed to D S Macpherson.

At least 19 recordsLinked to original sources
PubMed1998

Hyperkalemia in outpatients using angiotensin-converting enzyme inhibitors. How much should we worry?

BACKGROUND: Hyperkalemia is a potentially life-threatening complication resulting from the use of angiotensin-converting enzyme (ACE) inhibitors; data to guide the intensity of monitoring for or responding to hyperkalemia in outpatients are limited. METHODS: Case-control methodological procedures were used to identify risk factors for hyperkalemia. Outpatients prescribed ACE inhibitors during 1992 and 1993 at a Veterans Affairs medical center general medicine clinic were identified. Case patients had a potassium level higher than 5.1 mmol/L on the day of clinic visit while using an ACE inhibitor; controls had a potassium level lower than 5.0 mmol/L on the day of clinic visit while using an ACE inhibitor and had no elevated potassium level during the study period. Predictor variables measured included type and dosage of ACE inhibitor; serum chemistries; comorbidities; concurrent drug use; and age. Case patients were followed up for 1 year after the index episode of hyperkalemia. Follow-up variables included changes in therapy with ACE inhibitor, maximum potassium for each change, and mortality. RESULTS: Of 1818 patients using ACE inhibitors, 194 (11%) developed hyperkalemia. Results of laboratory studies indicating a serum urea nitrogen level higher than 6.4 mmol/L (18 mg/dL), creatinine level higher than 136 mumol/L (1.5 mg/dL), congestive heart failure, and long-acting ACE inhibitors were independently associated with hyperkalemia; concurrent use of loop or thiazide diuretic agent was associated with reduced risk. After 1 year of follow-up, 15 (10%) of 146 case patients remaining on a regimen of an ACE inhibitor developed severe hyperkalemia (potassium level > 6.0 mmol/L). A serum urea nitrogen level higher than 8.9 mmol/L (25 mg/dL) and age more than 70 years were independently associated with subsequent severe hyperkalemia. CONCLUSIONS: Mild hyperkalemia is common in medical outpatients using ACE inhibitors, especially in those with renal insufficiency or congestive heart failure. However, once hyperkalemia is identified during the use of ACE inhibitors, subsequent severe hyperkalemia is uncommon in patients younger than 70 years with normal renal function.

Ambulatory Care↗
PubMed1998

Digital ischaemia: an unusual presentation of dysbarism.

Dysbaric symptoms following ascent from a scuba dive are due to symptomatic nitrogen or air emboli with clear patterns of associated injury. This case report highlights an unusual presentation of dysbaric injury treated successfully with a prostacyclin analogue.

Adolescent↗
PubMed1995

Management of lower limb ischaemia associated with the use of intra-aortic balloon pumps during cardiac surgery.

OBJECTIVE: To audit the lower limb vascular complications associated with the use of an intraaortic balloon pump (IABP) on a cardiothoracic unit over a 12 month period. DESIGN: Retrospective analysis. SETTING: Regional university cardiothoracic unit. PATIENTS: Fifty four IABPs inserted into 51 patients. RESULTS: Seventeen patients (33%) died from cardiogenic shock in the immediate postoperative period. Of the remaining 34 patients (37 IABPs), lower limb vascular complications occurred in nine patients (26%) who underwent 11 IABP insertions (30%). Vascular complications included groin haematomas (n = 2 insertions), compartment syndrome (n = 2 insertions), femoral artery trauma (n = 7 insertions). CONCLUSIONS: Prompt management by peripheral vascular surgeons resulted in limb salvage in 10 legs and only one death from a pulmonary embolus.

Acute Disease↗
PubMed1995

The additional value of intraoperative angiography in infragenicular reconstruction.

OBJECTIVE: To evaluate the ability of preoperative intraarterial digital subtraction angiography (IADSA) to predict the feasibility of infragenicular reconstruction and site of the distal anastomosis. DESIGN: Prospective study. SETTING: University Hospital MATERIALS: 45 patients with 50 ischaemic limbs, considered potential candidates for infragenicular reconstruction. CHIEF OUTCOME MEASURES: Pre-reconstruction intraoperative angiography (IOA) was used as the gold standard. Analysis of angiograms was performed blindly and independently by a single observer. In patients who ultimately underwent primary amputation, exploration and attempted angiography of the crural and ankle vessels was performed to verify the IADSA findings. MAIN RESULTS: There was 87% accuracy (kappa = 0.66) between IADSA and IOA in differentiating between a normal, stenosed and occluded tibial artery and there was 86% accuracy (kappa = 0.67) in determining the adequacy of run-off into the pedal arch. IADSA had a positive predictive value of 100% to determine the feasibility of reconstruction but a negative predictive value of only 73%. After excluding those patients tha IADSA deemed non-reconstructable, IADSA had a positive predictive value of 97% to determine the correct artery and 92% to determine the correct segment of artery for distal anastomosis. CONCLUSIONS: IADSA could not determine when reconstruction was not possible, but in those deemed reconstructable by IADSA, the surgeon can confidently expose the appropriate artery at the appropriate level knowing the pedal run-off status in 86% of patients. IADSA should not be used to exclude reconstruction (i.e. pre-reconstruction IOA is still required in these patients) but for the remainder, IADSA can be used to plan surgical strategy without recourse to IOA.

Amputation, Surgical↗
PubMed1994

An internist joins the surgery service: does comanagement make a difference?

OBJECTIVE: To determine the effect of internist comanagement of cardiothoracic surgical patients on patient outcome and resource utilization. DESIGN: Before/after comparison. SETTING: Tertiary care university-affiliated Veterans Affairs hospital. PATIENTS: 165 patients (86 before the intervention and 79 after the intervention) undergoing cardiothoracic surgery. INTERVENTIONS: All patients were seen preoperatively and at least daily through discharge by a comanaging staff internist who was a full-time member of the surgical team. MAIN OUTCOME MEASURES: Length of stay, in-hospital mortality, and laboratory and radiology utilization. RESULTS: Significant shortening of postoperative length of stay (18.1 days before and 12.1 days after, p = 0.05) and total length of stay (27.2 days before and 19.7 days after, p = 0.03) was noted. The in-hospital mortality rate for the patients undergoing surgery was 8.1% before the intervention versus 2.5% afterward (p = 0.17). There were significant reductions in the total number of x-rays (p = 0.02) and nearly significant reductions in total laboratory test utilization (p = 0.06). Referring physicians and surgeons both believed that the contribution of the internist was important. CONCLUSIONS: The addition of an internist to the cardiothoracic surgery service at a tertiary care teaching center was associated with decreased resource utilization and possible improved outcomes. Before becoming more widely adopted, this intervention deserves further exploration at other sites using stronger study designs.

Hospital Mortality↗
PubMed1994

Outpatient internal medicine preoperative evaluation: a randomized clinical trial.

The purpose of this study was to evaluate the effect on resource use of a program outpatient internal medicine preoperative evaluation in a two arm parallel design randomized clinical trial. In a tertiary care teaching Veterans Affairs hospital, 355 patients (179 inpatient arm, 176 outpatient arm)(mean age 65.5 years) were referred for internal medicine preoperative evaluation before elective surgery. Outpatient internist preoperative evaluation was performed 2 to 3 weeks before admission for surgery in the experimental arm with preoperative laboratory and radiology testing performed during the visit. The control arm was admitted for surgery without outpatient evaluation. The main outcome measure was the length of stay. Preoperative length of stay was significantly reduced from 2.9 days in the inpatient arm to 1.6 days in the outpatient arm (P < 0.001, 95% confidence interval of the difference, -0.8 to -1.8 days). Postoperative length of stay in the outpatient arm (3.6 days) was slightly but not significantly longer than the inpatient arm (3.0 days) (95% confidence interval of the increase, -0.6 to 1.8 days). Total length of stay showed no significant difference between the outpatient (5.5 days) and inpatient (6.0 days) arms (95% confidence interval of the difference, -2.0 to 1.1 days). Unnecessary admissions, defined as patients admitted who were admitted but did not undergo surgery, were decreased significantly comparing the inpatient arm (12.3%) to the outpatient arm (5.7%) (95% confidence interval of the difference, 0.5% to 12.7%). Measures of resource use showed no difference between arms including laboratory tests (95% C.I. of the difference, -3.0 to 6.8 tests), imaging tests (95% C.I. of the difference, -0.5 to 0.8 tests) were administered. A significant increase in the use of consultants between the outpatient arm (1.3 consultations) and inpatient arm (0.9 consultations) was discovered (95% C.I. of the difference, 0.2 to 0.6). Patients health status after discharge and satisfaction with care were not different between the two arms of the investigation. A program of outpatient internal medicine preoperative evaluation significantly reduced preoperative length of stay with a lesser effect on total length of stay. Unnecessary admission of patients for elective surgery were reduced by this program.

Aged↗
PubMed1994

Successful resection of a massive hepatic artery aneurysm.

Hepatic artery (HA) aneurysms are seen infrequently, but many eventually rupture, often with a fatal outcome. With modern diagnostic technology, aneurysms can be identified at an earlier stage, providing the opportunity for intervention. This review outlines the case of a patient with a massive, leaking hepatic artery aneurysm and discusses the aetiology and management of these lesions.

Aged↗
PubMed1993

Preoperative laboratory testing: should any tests be "routine" before surgery?

Routine preoperative testing of all patients before elective surgery is unjustified. The frequency of unanticipated abnormalities or abnormalities shown to change patient management is too low to justify a practice pattern of testing all patients. Furthermore, little evidence exists that test result abnormalities are associated with perioperative morbidity. Table 12 lists a compilation of the findings from this article and recommendations regarding routine testing.

Blood Cell Count↗
PubMed1990

Preoperative screening: value of previous tests.

OBJECTIVE: To determine the frequency of tests done in the year before elective surgery that might substitute for preoperative screening tests and to determine the frequency of test results that change from a normal value to a value likely to alter perioperative management. DESIGN: Retrospective cohort analysis of computerized laboratory data (complete blood count, sodium, potassium, and creatinine levels, prothrombin time, and partial thromboplastin time). SETTING: Urban tertiary care Veterans Affairs Hospital. PATIENTS: Consecutive sample of 1109 patients who had elective surgery in 1988. MEASUREMENTS AND MAIN RESULTS: At admission, 7549 preoperative tests were done, 47% of which duplicated tests performed in the previous year. Of 3096 previous results that were normal as defined by hospital reference range and done closest to the time of but before admission (median interval, 2 months), 13 (0.4%; 95% CI, 0.2% to 0.7%), repeat values were outside a range considered acceptable for surgery. Most of the abnormalities were predictable from the patient's history, and most were not noted in the medical record. Of 461 previous tests that were abnormal, 78 (17%; CI, 13% to 20%) repeat values at admission were outside a range considered acceptable for surgery (P less than 0.001, frequency of clinically important abnormalities of patients with normal previous results with those with abnormal previous results). CONCLUSIONS: Physicians evaluating patients preoperatively could safely substitute the previous test results analyzed in this study for preoperative screening tests if the previous tests are normal and no obvious indication for retesting is present.

Aged↗
PubMed1990

Deciding to restrain medical patients.

To determine when and why patients are placed in mechanical restraints, we surveyed the nurse and physician caring for each of 102 restrained patients from the general medical floors of an acute-care hospital. Ninety-three percent of the questionnaires were completed. Nursing questionnaires indicated that over half of patients were restrained during the evening shift. Nurses initiated the use of restraints in 75% of cases. Fifteen percent of the patients' physicians were unaware that the patient had been restrained. In the majority of cases, the nurse and physician believed that restraint was the best alternative for managing the patient although more physicians (11%) than nurses (2%) thought an alternative intervention would be better (P less than .02). As a group, physicians and nurses restrained patients for similar reasons, most often to prevent falls from bed (69%) or to protect medical devices (36%). However, there was poor agreement between the nurse and physician as to the reason for restraint in an individual patient (kappa statistic range from .02 to .43). These findings suggest that nurse and physician communication regarding restraint is poor. We recommend that acute-care hospitals adopt policies to promote communication between nurses and physicians concerning restraints to ensure that use of this potentially hazardous intervention is used only when necessary.

Accidental Falls↗
PubMed1990

Testicular teratoma and peripheral neurofibromatosis.

Peripheral neurofibromatosis (Von Recklinghausen's disease) has been previously reported in association with a number of tumours and recently with aqueductal stenosis. We report a case which had both aqueductal stenosis and a testicular teratoma, which has not previously been reported in this condition.

Adult↗