Biomedical subjects

V L Baughman

Publications and source records attributed to V L Baughman.

41 records · Page 3Linked to original sources

PubMed1986

Effects of phenobarbital on cerebral blood flow and metabolism in young and aged rats.

The cerebrovascular and cerebral metabolic changes produced by intraperitoneal injection of phenobarbital (50, 150, and 250 mg/kg) were studied in young adult (6-month) and senescent (28-month) Wistar rats. Cerebral blood flow (CBF) was measured using radioactive microspheres and cerebral oxygen consumption (CMRO2) was obtained by multiplying cortex CBF by the arterial-sagittal sinus oxygen content difference. Control values for blood pressure, blood gas tensions, CBF, and CMRO2 were similar in the young and aged animals during 70% N2O/30% O2. Intraperitoneal phenobarbital produced dose-dependent decreases in CBF with no significant difference between young and aged rats at each phenobarbital dose. At the highest phenobarbital dose (250 mg/kg) CBF was reduced by 49% in the young rats and 52% in the aged rats (P greater than 0.10). CMRO2 was also depressed in a dose-dependent fashion in both young and aged animals with each phenobarbital dose. However, the decrease produced by the highest phenobarbital dose was significantly greater in the aged rats (55%) than the young rats (43%, P less than 0.05), even though the EEG was isoelectric in both groups. The difference in CMRO2 between young versus aged rats at a time when the EEG is isoelectric suggests that high-dose phenobarbital may depress nonelectrical cerebral metabolic processes more in aged rats.

Aging↗

PubMedDate not supplied

The effectiveness of oral clonidine as a sedative/anxiolytic and as a drug to blunt the hemodynamic responses to laryngoscopy.

STUDY OBJECTIVE: To determine the effects of oral clonidine premedication on sedative, anxiolytic, and hemodynamic responses during the immediate preoperative period, laryngoscopy/intubation, and postanesthetic recovery. DESIGN: Randomized double-blind assignment to one of four treatment groups (clonidine 0.1 mg, clonidine 0.2 mg, triazolam 0.25 mg, or placebo); n = 10 per group. SETTING: Inpatient surgery in a university-staffed tertiary center. PATIENTS: Forty ASA physical status I and II adults of both sexes scheduled for a variety of procedures requiring general anesthesia. INTERVENTIONS: Anxiety and sedation scored on ordinal scale at time of treatment and 90 minutes later, just prior to anesthetic induction. Standardized induction protocol with automated hemodynamic monitoring at 1-minute intervals and a 45-second laryngoscopy to ensure a vigorous stress response. MEASUREMENTS AND MAIN RESULTS: Triazolam and both doses of clonidine increased sedation at 90 minutes both absolutely and compared with a placebo. Clonidine 0.2 mg decreased anxiety absolutely at 90 minutes but no more than a placebo. Clonidine 0.2 mg decreased systolic, mean, and diastolic blood pressures (BPs) but not heart rate (HR) at 90 minutes. Clonidine 0.2 mg also blunted the increase in systolic blood pressure (SP) [but not in diastolic blood pressure (DP) or HR] that accompanied laryngoscopy. There were no treatment differences in postanesthetic hemodynamics or duration of recovery. CONCLUSIONS: Oral clonidine 0.2 mg was effective in reducing the level of behavioral and hemodynamic responses preoperatively and in blunting systolic hypertension produced by prolonged laryngoscopy.

Adult↗

PubMedDate not supplied

Lidocaine blood levels following aerosolization and intravenous administration.

STUDY OBJECTIVE: To determine whether, following aerosolization of lidocaine for topical airway anesthesia, intravenous (IV) lidocaine produces toxic lidocaine blood concentrations. DESIGN: Randomized, double-blind study. SETTING: University-affiliated hospital. PATIENTS: Forty healthy patients scheduled for outpatient surgery. INTERVENTIONS: The patients received in a randomized, double-blind manner aerosolized lidocaine or placebo followed 10 minutes later by IV lidocaine or placebo. MEASUREMENTS AND MAIN RESULTS: After completion of lidocaine or placebo aerosolization and 2 minutes following IV administration of either lidocaine or the placebo, venous blood samples were obtained. Lidocaine concentration was measured using a homogenous enzyme assay. The group receiving both aerosolized and IV placebo and the group receiving aerosolized lidocaine and an IV placebo had undetectable (less than 0.05 micrograms/ml) serum lidocaine levels. The groups that received either an aerosolized placebo or aerosolized lidocaine and IV lidocaine had similar serum lidocaine concentrations [3.34 +/- 0.46 vs. 3.24 +/- 0.55 micrograms/ml (mean +/- SEM); p greater than 0.05 by Mann-Whitney U test]. CONCLUSION: IV lidocaine can be safely administered following aerosolization of lidocaine in spontaneously breathing patients without producing toxic blood lidocaine concentrations.

Aerosols↗

PubMedDate not supplied

Oral clonidine blunts the hemodynamic responses to brief but not prolonged laryngoscopy.

STUDY OBJECTIVE: To determine whether a 300 micrograms dose of oral clonidine given 90 minutes prior to laryngoscopy and intubation provides hemodynamic protection from the stress of a brief (15-second) and/or a prolonged (45-second) laryngoscopy. DESIGN: Randomized, double-blind, placebo-controlled study. SETTING: Inpatients and outpatients scheduled for general anesthesia with intubation at a university-affiliated medical center. PATIENTS: Forty patients who gave informed, written consent to receive either an oral placebo or clonidine 5 micrograms/kg (up to a maximum dose of 300 micrograms) 90 minutes prior to induction of anesthesia and to undergo either brief or prolonged laryngoscopy prior to intubation. INTERVENTIONS: The patients underwent a standardized induction sequence that included d-tubocurarine 3 mg, thiopental sodium 5 mg/kg, and succinylcholine 1.5 mg/kg. The four treatment groups (each n = 10) included (1) placebo with 15-second laryngoscopy, (2) placebo with 45-second laryngoscopy, (3) clonidine with 15-second laryngoscopy, and (4) clonidine with 45-second laryngoscopy. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were mechanically obtained and recorded at 1-minute intervals for 12 minutes. MEASUREMENTS AND MAIN RESULTS: There were no differences between groups in the premedication hemodynamic measurements. Within each group, maximal hemodynamic variables increased significantly over the corresponding baseline values for that group. In the 15-second, but not the 45-second, laryngoscopy, clonidine successfully blunted the maximum SBP and DBP obtained when compared with the corresponding control group. In both the 15- and 45-second clonidine groups, maximum HR was significantly lower than in the corresponding placebo groups. CONCLUSIONS: Oral clonidine, when used as a preoperative medication, affords hemodynamic protection to patients undergoing a 15-second laryngoscopy. However, the stress of a 45-second laryngoscopy may be too great or the 300 micrograms dose of clonidine too low to provide hemodynamic protection for patients in this group.

Administration, Oral↗

PubMedDate not supplied

Comparative pharmacokinetics of oral versus sublingual clonidine.

STUDY OBJECTIVE: To compare the pharmacokinetic and pharmacodynamic profile of orally versus sublingually administered clonidine. DESIGN: Randomized, crossover, nonblinded, open-label study. SETTING: University tertiary-care center. PATIENTS: 10 healthy male and female volunteers aged 20 to 42 years. INTERVENTIONS: A heparinized catheter was placed intravenously for blood-sampling purposes. An automatic sphygmomanometer was placed on the volunteers' left upper arm to obtain systolic and diastolic blood pressure, and a pulse oximeter was placed on the right index finger to measure heart rate (HR). MEASUREMENTS AND MAIN RESULTS: Serial blood samples were collected throughout the 24-hour study period to determine clonidine concentrations. The effect of clonidine on blood pressure (BP) and HR also was measured. The half-life, area under the curve, maximum concentration, and time to reach maximum concentration were similar for both the sublingual and oral routes. BP and HR changes were similar for both sublingual and oral clonidine. CONCLUSION: Both routes of administration resulted in similar pharmacokinetic and pharmacodynamic profiles. Attempts to shorten clonidine's latency with sublingual administration were unsuccessful. Our study shows that a single dose of clonidine 0.3 mg has the same pharmacokinetic and dynamic profile when administered orally or sublingually. Therefore, the sublingual route can be predictably used in fasting patients, those having difficulty swallowing, or those who are unable to absorb drugs through the gastrointestinal tract; the sublingual dose is the same as the oral dose.

Administration, Oral↗