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Biomedical subjects

R B Smith

Publications and source records attributed to R B Smith.

At least 127 records · Page 7Linked to original sources
PubMed1992

Pulmonary effects of body position, PEEP, and surfactant depletion in dogs.

The influence of position (sphinx, lateral, supine), surfactant depletion, and different positive end-expiratory pressure (PEEP) on functional residual capacity (FRC), series dead space (VdS) and compliance of the respiratory system (Crs) were evaluated in five dogs. Ventilation homogeneity as measured by an index (multiple breath alveolar mixing efficiency), oxygenation, and cardiovascular hemodynamics were additionally examined. The dogs were anesthetized with halothane, paralyzed, and mechanically ventilated. FRC and VdS were found to be notably large in dogs, 45 +/- 8 ml/kg and 6 +/- 1 ml/kg, respectively. FRC and ventilation homogeneity were improved in the sphinx position (prone position with upright head). Surfactant depletion by lung lavage with 37 degrees C saline caused an immediate and stable decrease in FRC, Crs, and oxygenation (P less than 0.05, respectively) for about 5 h without marked effects on the circulatory system. FRC and VdS increased with increasing PEEP. At the highest PEEP, 10 cmH2O (1 kPa), Crs decreased (P less than 0.05) and ventilation became more uneven, indicating alveolar overdistension.

Animals↗
PubMed1992

The Leeds-Keio prosthesis in chronic anterior cruciate deficiency.

A woven polyester graft is used in chronic anterior cruciate instability. Twenty-five patients were reviewed with an average follow-up period of almost five years. The patients were assessed in terms of function, clinical examination, and residual laxity. The results showed that four could be classified as excellent, 16 good, and four poor. Fifty-two percent of patients returned to their preaccident level of activity, and there did not appear to be any evidence of increasing laxity with time. All patients had a good range of flexion with no extension loss. This prosthesis, along with its unique method of fixation, offers a simple alternative to patellar tendon or soft tissue reconstructions in the chronic anterior cruciate-deficient knee.

Adolescent↗
PubMed1992

OSHA reform.

Explore the source record for details and available documents.

Humans↗
PubMed1992

Acute arterial thrombosis in the very young.

The case records of all infants under the age of 6 months who underwent surgery for acute arterial thrombosis between January 1980 and September 1991 were reviewed. Seven infants (nine ischemic limbs) were identified and ranged in age from 5 days to 5 1/2 months (mean 2.4 months); all weighed less than 5 kg (mean 3.9 kg). The cause in each case was iatrogenic. Diagnosis was based on the presence of a cool, mottled extremity associated with the absence of insonated peripheral arterial Doppler signals. Treatment included aortoiliac thrombectomy (n = 2), femoral artery thrombectomy with primary closure (n = 4), femoral artery thrombectomy with autogenous saphenous vein patch (n = 1), and axillary artery thrombectomy with end-to-end anastomosis (n = 1). Palpable pulses were restored in five (56%) of nine limbs and Doppler signals in the remaining limbs. There were no instances of limb loss. Excluding aortoiliac thrombectomy, palpable peripheral pulses were reestablished in only 40% of extremities. Thrombectomy is a safe and simple procedure in even the very youngest of patients with arterial insufficiency, but surgical optimism should be tempered by frequent inability to achieve full and durable success.

Acute Disease↗
PubMed1992

Vena caval interruption.

While anticoagulation remains the treatment of choice for acute pulmonary thromboembolism, vena caval interruption represents an alternative for persons with either a contraindication to or a complication of anticoagulation. The authors retrospectively reviewed their experience with vena caval interruption over a recent 5-year period. One hundred seven Greenfield filters (Medi-Tech; Watertown, MA) and 13 external vena caval clips were used in 120 patients. Indications for caval interruption were: 1) contraindication to anticoagulation (38%), 2) recurrent pulmonary embolism despite adequate anticoagulation (23%), 3) prophylaxis (22%), and 4) complications associated with anticoagulation (17%). Vena caval interruption was successfully accomplished in 98 per cent of attempts. The overall complication rate was 7 per cent, with no procedure-related major morbidity or mortality. Sixty-five patients were followed for a mean of 36 months. In that interval, there were the following: 1) one instance of venous stasis ulceration, 2) two cases of late caval thrombosis, and 3) one person with documented recurrent pulmonary emboli. Significant edema requiring support stockings was reported in 16 per cent of persons with Greenfield filters and 37 per cent of those with caval clips. Vena caval interruption by use of the Greenfield filter is a safe and effective means of protecting against pulmonary embolism with few immediate or long-term complications.

Adolescent↗
PubMed1992

Vascular complications following intra-aortic balloon pump insertion.

The intra-aortic balloon pump (IABP) has been used for 23 years to treat cardiogenic shock from various causes. A retrospective review was conducted to evaluate the morbidity, mortality, and risk factors associated with insertion of this device. Over a recent 3-year period, 415 such pumps were inserted either by percutaneous (323) or cut-down (92) technique in 404 patients. Indications for placement included intraoperative pump failure (46%), cardiac instability before coronary artery bypass grafting (28%), perioperative support (13%), cardiac transplantation (7%), and cardiogenic shock (6%). Noncardiac vascular complications occurred in 67 patients, 55 per cent of whom required surgical correction. Operative procedures included femoral artery thrombectomy, bypass grafting, fasciotomy, and amputation. Major risk factors for vascular complications included diminished or absent femoral pulses on initial examination, being a woman, and obesity. In patients with known peripheral vascular disease, the risk of a vascular complication was 17.9 per cent when a surgical cut-down technique was used to insert the IABP, and 38.9 per cent when a percutaneous insertion was performed. The mortality doubled in those patients who had a vascular complication as compared to those who did not (34% vs 17%). A more liberal use of an open surgical technique in those patients with peripheral vascular disease, obesity, and who are women may help to reduce complications after the insertion of the intra-aortic balloon pump.

Adolescent↗
PubMed1991

Alprazolam in end-stage renal disease: I. Pharmacokinetics.

In a double-blind, randomized, placebo-controlled study, the pharmacokinetics of alprazolam and its active metabolite, alpha-hydroxyalprazolam, were determined in 12 normal subjects and 12 dialysis patients [7 hemodialysis (HD) patients and 5 continuous ambulatory peritoneal dialysis (CAPD) patients]. Blood samples were collected over 48 hours after alprazolam 0.5 mg and alprazolam 2 mg administration. Alprazolam and alpha-hydroxyalprazolam concentrations and alprazolam free fraction were determined. The pharmacokinetics of alprazolam were similar in normal subjects and HD patients with the exception of higher free fraction in HD patients. Differences were detected, however, in the pharmacokinetics of alprazolam in CAPD patients when compared with normal subjects and HD patients. These differences included a higher free fraction and a lower apparent oral clearance and free clearance in CAPD patients than in normal subjects or in HD patients. There was also a tendency for a later Tmax and a longer elimination half-life in CAPD patients than in normal subjects or HD patients. Alpha-hydroxyalprazolam concentrations were less than 15% of corresponding alprazolam concentrations in normal subjects and dialysis patients. Thus, end-stage renal disease is associated with changes in absorption, distribution, and/or elimination of alprazolam.

Adult↗
PubMed1991

Comparison of adinazolam pharmacokinetics and effects in healthy and cirrhotic subjects.

The pharmacokinetics and pharmacodynamics of adinazolam were investigated in six patients with cirrhosis and six sex-matched control subjects. These subjects received a single 30-mg oral dose of adinazolam mesylate. Serial blood samples were collected for 24 hours after drug administration. Plasma was assayed for adinazolam and mono-desmethyl-adinazolam (NDMAD) concentrations by a specific HPLC technique. Pharmacokinetic parameters were estimated by noncompartmental methods. Psychomotor effects of adinazolam were assessed using a digit-symbol substitution test (DSST) and aiming test (AIM). Memory effects were assessed by a modification of the Randt memory test (MEM); sedation was assessed using an observer-rated scale. Differences in pharmacokinetics of the parent drug were noted: adinazolam oral clearance was lower in patients with cirrhosis (35.0 +/- 27.9 L/hr) than in normal subjects (73.7 +/- 22.1 L/hr; P = .024); Kel was significantly lower in patients with cirrhosis (.126 +/- .084 vs. .278 +/- .070; P = .007), whereas the mean t1/2 in patients with cirrhosis was 7.70 hours as compared with 2.67 hours in normal subjects. Cmax was higher in the group with cirrhosis (266 +/- 95.5 vs. 153 +/- 29.3 ng/mL; P = .019). For NDMAD, Kel was lower in cirrhotic subjects and resulted in a prolonged t1/2 in cirrhotic subjects compared with normal subjects (6.70 vs. 3.79 hr; P = .0152). NDMAD AUC tended to be higher in cirrhotic subjects (1515 +/- 254 vs. 1162 +/- 254 ng.hr/mL; P = .064). No significant differences were noted in psychomotor performance, memory, or sedation.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Renal cell carcinoma with inferior vena caval involvement.

Renal cell carcinoma extends into the lumen of the inferior vena cava in approximately 4% of patients at the time of diagnosis. Surgical removal of the intracaval tumor thrombus with radical nephrectomy is the preferred treatment for this malignancy. From January 1977 to June 1990, 31 such patients were examined for combined problems of renal carcinoma and intracaval tumor extension. Twenty-six of these patients underwent radical nephrectomy and vena caval thrombectomy. Ten patients had tumor thrombus confined to the infrahepatic vena cava, 11 had retrohepatic caval involvement, and 5 had extension to the level of the diaphragm or into the right atrium. Surgical approach was dictated by the level of caval involvement. Control of the suprahepatic vena cava plus temporary occlusion of hepatic arterial and portal venous inflow were necessary in some cases; cardiopulmonary bypass was required for transatrial removal of more extensive tumors. Five of the 26 patients had evidence before operation of distant metastatic disease; none of these survived beyond 12 months. The 5-year actuarial survival rate of the 21 patients without known preoperative metastatic disease was 57%. Complete surgical excision of all gross tumor appears to be critical for long-term survival in these patients.

Adolescent↗