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R F McLean

Publications and source records attributed to R F McLean.

23 records · Page 2Linked to original sources
PubMed1990

Vasodilator therapy in microembolic porcine pulmonary hypertension.

The hemodynamic effects of prostaglandin E1, sodium nitroprusside (SNP), nitroglycerin, and hydralazine were studied in a porcine model of elevated pulmonary vascular resistance (PVR) due to glass bead microembolization (60-150-microns diameter). Each animal received all four drugs. Each drug was titrated to produce a 30% reduction in mean systemic arterial pressure. Although all four drugs decreased PVR, distinct differences in the hemodynamic profiles of the four drugs were evident. Prostaglandin E1 produced the largest reduction in mean pulmonary artery pressure (from 41 +/- 1 to 32 +/- 9 mm Hg, mean +/- SEM) and PVR (25 +/- 3 to 18 +/- 2 mm Hg.L-1.min-1), and did not affect the ratio of PVR to systemic vascular resistance (PVR/SVR). Sodium nitroprusside and nitroglycerin produced moderate decreases in PVR (nitroglycerin 21 +/- 2 to 18 +/- 2 mm Hg.L-1.min-1, SNP 22 +/- 2 to 19 +/- 2 mm Hg.L-1.min-1) and in mean pulmonary artery pressure (nitroglycerin 39 +/- 1 to 35 +/- 1; SNP 40 +/- 1 to 36 +/- 2 mm Hg). Both drugs significantly increased the PVR/SVR ratio. Hydralazine was the only drug that significantly increased cardiac output (1.6 +/- 0.2 to 1.9 +/- 0.3 L/min). Hydralazine had no significant effect on mean pulmonary artery pressure, reduced PVR to the smallest extent (11%), and resulted in the largest increase in the PVR/SVR ratio (from 0.52 +/- 0.04 to 0.80 +/- 0.08). In this model of increased pulmonary vasculature resistance prostaglandin E1 caused an equivalent amount of pulmonary and systemic vasodilation, as expressed by the PVR/SVR ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1988

Effects of spinal anesthesia on response to main pulmonary arterial distension.

Nonocclusive main pulmonary arterial distension produces peripheral pulmonary hypertension. The mechanism of this response is unknown. The effects of total spinal anesthesia on the response were studied in halothane-anesthetized dogs. Before total spinal anesthesia, main pulmonary arterial balloon inflation increased pulmonary arterial pressure and resistance without affecting systemic hemodynamic variables. Both right and left pulmonary arterial pressures were monitored to exclude unilateral obstruction with main pulmonary arterial balloon inflation. Total spinal anesthesia decreased cardiac output and systemic arterial pressures. After total spinal anesthesia, main pulmonary arterial distension still increased pulmonary arterial pressure and resistance. Right atrial pacing, discontinuation of halothane anesthesia, and norepinephrine infusion during total spinal anesthesia partially reversed the hemodynamic changes caused by total spinal anesthesia. The percent increase in pulmonary vascular resistance due to main pulmonary arterial distension was similar before total spinal anesthesia and during all experimental conditions during total spinal anesthesia. The pulmonary hypertensive response is therefore not dependent on central synaptic connections.

Anesthesia, Spinal↗
PubMed1985

Outcome of respiratory intensive care for the elderly.

We followed 1018 patients admitted consecutively to a multidisciplinary respiratory ICU (RICU), with special attention to patients aged 75 yr and over. The elderly had a higher RICU (11/49) and in-hospital (21/49) mortality than younger patients. The 28 survivors of hospitalization had a lower acute physiology score (APS) than nonsurvivors on admission (16.1 +/- 7.8 vs. 21.8 +/- 8.9, respectively), indicating less severe illness. The quality of long-term survival (12 to 24 months) was assessed using an open-ended questionnaire. Eighteen hospital survivors were alive at the time of follow-up and the quality of life was deemed satisfactory by 10 of 13 patients who were living independently. Only two of 28 survivors had been transferred to nursing home care, and two were in acute care hospitals. We conclude most elderly patients discharged from the RICU consider their lifestyle satisfactory and are not a large drain on community health care resources. Further studies of the screening process which determines RICU admission are necessary, because unimodal criteria such as age and APS after admission were not of prognostic value.

Age Factors↗