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Biomedical subjects

B M Parker

Publications and source records attributed to B M Parker.

At least 19 recordsLinked to original sources
PubMed2000

Redefining the preoperative evaluation process and the role of the anesthesiologist.

STUDY OBJECTIVE: To assess the effects of implementing an ambulatory and same-day surgery preoperative evaluation patient triage system over a 3-year period. DESIGN: Retrospective analysis of 63,941 ambulatory surgical patients presenting for elective surgery. SETTING: Tertiary care, academic medical institution. INTERVENTIONS: The following preoperative evaluation model components were implemented over a 3-year period: HealthQuest, which is an outpatient preoperative assessment computer program developed by the Department of General Anesthesiology; a general internal medicine clinic designated specifically for preoperative evaluation and medical optimization; disease specific algorithms for both preoperative patient assessment and management; and a preoperative anesthesia clinic that no longer performs preoperative medical optimization. MEASUREMENTS AND MAIN RESULTS: During the 3-year study period ambulatory and same-day surgical case volume increased 34.7%. A total of 50,967 patients used HealthQuest as part of their preoperative evaluation. Of these patients 22,744 (35.6%) did not need to see an anesthesiologist until the day of surgery as guided by both a computer-assigned HealthQuest score and surgical classification scheme. Also, 41,197 patients were evaluated in our anesthesia preoperative clinic with a cost per evaluation of $24.86, which increased only 0.9% per year. In addition, both patient interview time and patient dissatisfaction with the preoperative process decreased over the 3-year period. There were 20, 088 patient encounters in the general internal medicine clinic for patient medical evaluation and optimization. The average monthly preoperative surgical delay rate decreased 49% during the study period. Finally, significant monetary saving resulted due to decreased unnecessary laboratory testing. CONCLUSIONS: Efficient, cost-effective patient care can be provided by using this preoperative evaluation model. Some institutions may find portions of this preoperative model applicable to their current situation.

Algorithms↗
PubMed2000

Density and distribution of Dirofilaria immitis (Nematoda: Filarioidea) third-stage larvae in Aedes sollicitans and Aedes taeniorhynchus (Diptera: Culicidae).

Numbers and the distribution of third-stage larvae (L3) were investigated in Aedes sollicitans (Walker) and Aedes taeniorhynchus (Wiedemann) female mosquitoes fed Dirofilaria immitis (Leidy) infectious-blood with densities of microfilariae (mf) ranging from approximately 7,100-43,400 mf/ml. At each microfilarial density, a maximum of 63-66 infective larvae were recovered from an Ae. sollicitans alive on day 15 after infection. In comparison with Ae. taeniorhynchus, Ae. sollicitans averaged greater numbers of L3 and from 1.4 to 2.4 times more L3 in the head and labium per infected female. The trend was for greater numbers of L3 to be found in the labium than in the head of Ae. sollicitans, but there were no significant differences between numbers of L3 recovered from these sites in differentially infected females. However, numbers of L3 recovered from the head versus the labium of differentially infected Ae. taeniorhynchus varied significantly with the infectious blood microfilarial density. At the two lowest and highest microfilarial densities, greater numbers of L3 were recovered from the head and labium, respectively. Variations among species in the female body size, blood meal size, and retention of L3 may be factors responsible for differences observed between the total numbers and percentage distribution of D. immitis L3 recovered from the simultaneous blood-fed Ae. sollicitans and Ae. taeniorhynchus.

Aedes↗
PubMed1999

Is there occult tissue ischemia in chronic end-stage liver disease?

Whether pathological oxygen supply dependency exists in patients with chronic end-stage liver disease (CESLD) is unknown, although the frequently occurring multiorgan dysfunction seen in these patients may be the result of occult tissue ischemia. In this study, 15 adult patients with CESLD were evaluated for the presence of pathological oxygen supply dependency and, thus, occult tissue ischemia before undergoing orthotopic liver transplantation. Whole-body oxygen consumption (VO2) was measured using indirect calorimetry at baseline, at reduced oxygen delivery (DO2) using positive end-expiratory pressure, and at increased DO2 using volume infusion. As a group, no significant increase or decrease in VO2 was observed with changes in DO2. However, 4 patients showed increases in VO2 of 14%, 10.8%, 9.6%, and 8.2% when DO2 was increased. The study results suggest that pathological oxygen supply dependency is present in a subset of patients with CESLD, and the existence of occult tissue ischemia is speculated.

Adult↗
PubMed1999

Autonomic dysfunction in end-stage liver disease manifested as defecation syncope: impact of orthotopic liver transplantation.

Patients with end-stage liver disease (ESLD) may be at increased risk for syncopal episodes based on their circulatory physiological state. Although a definitive cause for this is not known, several mechanisms have been proposed. In patients with ESLD, defecation syncope may result from a failure of short-term neurocirculatory adaptation to the Valsalva maneuver in the face of a hyperdynamic circulatory state and a decreased effective intravascular volume. We describe 2 patients with ESLD who had repeated episodes of defecation syncope before orthotopic liver transplantation (OLT). The most effective treatment of these syncopal episodes appears to be fluid administration and the use of a pressor agent, such as dopamine, to help maintain both an effective heart rate and intravascular volume. Correction of this altered circulatory physiological state through OLT prevented further syncopal episodes in both patients. A search of the literature failed to show previous reports associating ESLD and defecation syncope. Possible mechanisms favoring this association are reviewed.

Adult↗
PubMed1998

Incidence and predictors of supraventricular dysrhythmias after pulmonary resection.

BACKGROUND: Patients undergoing pulmonary resection were evaluated prospectively in an effort to determine the incidence of and predictors for the development of postoperative supraventricular dysrhythmias. Specifically, we wished to test the hypothesis that the incidence of postoperative supraventricular dysrhythmias is dependent on the magnitude of pulmonary resection. METHODS: One hundred sixteen patients undergoing pulmonary resection had continuous Holter monitoring preoperatively, the day of operation, and the second postoperative day, as well as continuous cardiac monitoring throughout hospitalization. Holter interpretation was blinded to extent of resection. RESULTS: Twenty-six patients underwent pneumonectomy, 7 bilobectomy, 47 lobectomy, and 36 wedge resection. Twenty-six patients (22.4%) had supraventricular dysrhythmias, all atrial fibrillation +/- flutter. The incidence of atrial fibrillation with pneumonectomy, bilobectomy, single lobectomy, and wedge resection was 46.1%, 14.3%, 17.0%, and 13.8%, respectively (p < 0.005 pneumonectomy versus others). Overall, 31% of patients having pneumonectomy required pharmacologic therapy for dysrhythmia compared with 16% of patients having lesser resections, (p = 0.03). The peak incidence of onset of atrial fibrillation occurred on postoperative days 2 and 3 and lasted for less than 1 to 7 days, average 2.5 days. The average age of patients with dysrhythmias (64 years) was greater than those without (58 years) (p = 0.039). Thirty pre- and postoperative variables tested were not found to be significant predictors for development of postoperative atrial fibrillation. CONCLUSIONS: Atrial fibrillation occurs commonly after pulmonary resections but is not predictable. Development of atrial fibrillation is not dependent on the magnitude of pulmonary resection but is associated with the procedure pneumonectomy for reasons not elucidated.

Adult↗
PubMed1998

Sharps disposal in the operating room: current clinical practices and costs.

UNLABELLED: In the evolving medical environment, fiscal constraints on medical practice are becoming the norm. The new days of austerity have revived interest in the economics of medical practice. Economic measures, however, should not impinge on the quality of patient care. Waste disposal, in particular, is an area without any direct patient benefit but which carries both short- and long-term ecological costs. Much of how we dispose of waste is dictated in the United States by the Joint Commission for the Accreditation of Hospital Organization, Occupational Safety and Health Administration, state regulations, and individual hospital protocols. In an attempt to elucidate the waste in waste management, we examined the use of standard operating room sharp boxes. Full sharp boxes from three different operating sites were randomly saved. Boxes were weighed and opened, and contents were separated into appropriate sharps: loose needles, scalpels, syringes with uncapped needles, and other. Weight and volume assessments were performed on the nonsharps. True sharp values were derived from nonsharps data. Less than 50% of the contents were appropriate for sharps disposal, with empty glass vials constituting the greatest percentage by weight of nonsharps material. We believe that encouraging the appropriate use of sharps boxes is a potential source for savings. IMPLICATIONS: Sharp boxes were randomly saved from university operating rooms and analyzed for content. The full boxes contained 14% appropriate sharps by weight and <50% appropriate sharps by volume. The largest fraction of nonsharps weight was found to be glass.

Medical Waste Disposal↗
PubMed1997

Aging and drug interactions. III. Individual and combined effects of cimetidine and cimetidine and ciprofloxacin on theophylline metabolism in healthy male and female nonsmokers.

The individual and combined effects of cimetidine and ciprofloxacin on theophylline metabolism were examined in healthy young and elderly male and female nonsmokers. Single-dose studies of theophylline pharmacokinetics were performed at base line and on the fifth day of each of three treatment regimens consisting of 400 mg cimetidine every 12 hr, 500 mg ciprofloxacin every 12 hr and the combination of cimetidine and ciprofloxacin. Base-line theophylline plasma clearance and formation clearance of theophylline metabolites decreased with age in both gender groups to a similar extent (20% less in elderly men than in young men; 24% less in elderly women than in young women). Individually, cimetidine and ciprofloxacin produced proportionate declines in plasma theophylline clearance that were similar among the four groups (range, 23.4-32.7% decrease). The combined regimen yielded further impairment in theophylline elimination compared with each agent alone (range, 35.9-42.6% decrease). Cimetidine was a nonselective inhibitor of theophylline metabolic pathways in young men, but it exerted a greater inhibitory effect on N-demethylation pathways in the other groups. Ciprofloxacin inhibited N-demethylations of theophylline to a greater extent than the hydroxylation pathway. Coadministration of these two inhibitors further reduced the formation of theophylline metabolites. The proportionate reduction in formation clearance of theophylline metabolites was similar among the four groups. Thus, the response to inhibition of theophylline metabolism by cimetidine and ciprofloxacin is not influenced by age or gender.

Adult↗
PubMed1996

Relation between plasma and saliva concentrations of enoxacin, ciprofloxacin, and theophylline.

To assess the reliability of predicting plasma concentrations of enoxacin, ciprofloxacin, and theophylline from drug concentrations in saliva, six healthy volunteers received single oral doses of enoxacin, ciprofloxacin, and theophylline administered in combination on each of four separate study days, with different, doses separated by at least 5 days. Drug concentrations were determined by a newly developed high-performance liquid chromatography (HPLC) assay, which could measure simultaneously all three drugs in plasma or saliva. Saliva data from the postabsorptive phase after drug administration were used to minimize the effects of variation in absorption. There were good correlations between saliva and plasma concentrations of enoxacin, ciprofloxacin, and theophylline (r = 0.91, 0.88, and 0.98, respectively). The mean (+/-SD) saliva-to-plasma (S/P) ratio for theophylline was 0.63 +/- 0.06 with a coefficient of variation (CV) of 7.9 +/- 2.7%. In contrast, the S/P ratios and CV values for enoxacin and ciprofloxacin were 0.72 +/- 0.21 and 28.9 +/- 11.1%, and 0.58 +/- 0.15 and 25.3 +/- 6.7%, respectively. Because of the large inter- and intraindividual variability, saliva concentrations of enoxacin and ciprofloxacin are not reliable for predicting plasma concentrations. However, saliva may be used reliably for predicting plasma concentrations of theophylline.

Adult↗
PubMed1995

Pharmacokinetic optimisation of drug therapy in elderly patients.

With increasing age, there are a number of physiological changes that affect the handling of drugs in the human body. Increases in body fat percentage as well as decreases in lean body mass, hepatic metabolism and renal elimination capacity are of particular clinical significance. It is important to take these changes into account when choosing drug therapy for older patients in order to minimise adverse effects and maximise potential benefits. This is particularly important when prescribing drugs with a narrow therapeutic index such as digoxin, theophylline, phenytoin, lidocaine (lignocaine) or warfarin. When available, monitoring of plasma concentrations can assist in the optimisation of drug dosage.

Absorption↗
PubMed1994

Ileoanal teaching tools: developing a tool to meet a specific need.

As ET nurses working with ileoanal surgery patients for the first time in 1979, we discovered that there were no tools or materials available for teaching our patients how to care for themselves during the various stages of the procedure. Over the years, therefore, we have created a compilation of data based on answers to questionnaires completed by recent patients. This data base contains information on topics such as skin care and diet, and enables us to create teaching tools tailored to our own patient population. Although there are now other materials available for teaching self-care to ileoanal surgery patients, the ongoing collection of data from a particular group of patients can also help to create valuable teaching tools and enhance overall understanding of this complex procedure.

Humans↗
PubMed1993

Variation of mosquito (Diptera: Culicidae) relative abundance and Dirofilaria immitis (Nematoda: Filarioidea) vector potential in coastal North Carolina.

At an enzootic focus of Dirofilaria immitis in coastal North Carolina, mosquito populations were sampled June-September 1985 and on several occasions during August-October 1986 and June-August 1987, to identify local vectors and to determine relative abundance and D. immitis infection rates. Predominant species collected were Anopheles bradleyi King (66.6%), Culex salinarius Coquillett (15.9%), Aedes taeniorhynchus (Wiedemann) (8.2%), and Aedes sollicitans (Walker) (4.9%). Population abundance varied within and among seasons. D. immitis infection was found in An. bradleyi (1.2%), Ae. taeniorhynchus (0.9%), and Ae. sollicitans (0.9%). Of infected An. bradleyi, 88% were collected June-2 July, whereas the highest number of infected Ae. taeniorhynchus and Ae. sollicitans were found during mid-July 1985. Ae. sollicitans and Ae. taeniorhynchus were the only infected species found during 1986 and 1987. However, based on overall relative abundance and infective rate, An. bradleyi appeared to be the primary vector of D. immitis in the study area.

Aedes↗
PubMed1993

The effect of tocainide on theophylline metabolism.

The effect of 5 days of oral tocainide (400 mg every 8 h) on the kinetics of theophylline given as a single 5 mg kg-1 i.v. infusion over 30 min was investigated in eight healthy male nonsmokers. Treatment with tocainide decreased the plasma clearance of theophylline from 37.5 +/- 6.9 (mean +/- s.d.) to 33.7 +/- 5.0 ml kg-1 h-1 (difference -3.8, 95% CI, -1.7 to -5.9; P = 0.004) and increased its terminal elimination half-life from 9.7 +/- 2.5 to 10.4 +/- 2.1 h (difference 0.7, 95% CI, 0.2 to 1.2; P = 0.011). Tocainide decreased the formation clearances of 3-methylxanthine and 1-methyluric acid, but the formation clearance of 1,3-dimethyluric acid was unaltered. These data indicate that tocainide exerts a modest inhibitory effect on theophylline metabolism. The magnitude of this change is substantially smaller than that reported to be produced by mexiletine.

Adult↗
PubMed1993

Individual and combined effects of cimetidine and ciprofloxacin on theophylline metabolism in male nonsmokers.

1. The individual and combined effects of cimetidine and ciprofloxacin on theophylline metabolism were examined in six young male nonsmokers. 2. Treatment sequence consisted of 7 days each of cimetidine 400 mg p.o. every 12 h. ciprofloxacin 500 mg p.o. every 12 h, and the combination of cimetidine and ciprofloxacin. 3. Studies of theophylline pharmacokinetics were performed at baseline and on the fifth day of each regimen. 4. Individually, cimetidine and ciprofloxacin decreased the clearance of theophylline by 25% and 32%, respectively. Therapy with the combined regimen resulted in a 41% reduction in theophylline clearance, which was greater than that achieved with each drug alone (P < 0.01). 5. Ciprofloxacin, in contrast to cimetidine, inhibited N-demethylations of theophylline to a significantly greater extent than the hydroxylation pathway. Combined treatment produced a further decline in formation of 1,3-dimethyluric acid than each drug alone. 6. These data suggest that coadministration of cimetidine and ciprofloxacin exerts a greater impairment of theophylline biotransformation than each inhibitor alone. The enhanced inhibitory effect from the two inhibitors will occur only when sub-maximal doses of each individual agent are used.

Adult↗
PubMed1989

Aneurysmectomy prognosticators by equilibrium multi-gated cardiac blood pool scintigraphy.

Non-invasive assessment of left ventricular aneurysm (LVA) resection prognosticators was obtained in 13 multigated cardiac blood pool scintigrams by applying Fourier analysis to identify regions of interest. Results were compared to contrast ventriculograms performed at recent cardiac catheterization. Excellent correlation of the contractile section ejection fraction (CSEF) was found between the two techniques, r = .92 (P less than or equal to .0001). The CSEF correlated inversely with the left ventricular end diastolic pressure (LVEDP), r = .83 (P less than or equal to .0004), implying that LVEDP is not an independent prognosticator. The relative LVA size expressed as a fraction of the left ventricle in end diastole (LVASF) correlated less strongly with LVASF derived from contrast ventriculography, r = .67 (P = .012). This was probably due to additive inherent errors in contrast ventriculography geometric assumptions. Paradoxical stroke steal fraction (PSSF) defined as the reverse stroke lost in the LVA divided by the left ventricular forward stroke, was calculated from subtraction images. We propose a resectability score utilizing the product of the scintigraphically derived CSEF X LVASF X PSSF X 1,000 to obtain non-invasive pre-operative prognostication of LVA resection and post-operative evaluation.

Erythrocytes↗