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Biomedical subjects

D G Silverman

Publications and source records attributed to D G Silverman.

At least 19 recordsLinked to original sources
PubMed1992

A comparison of fentanyl, esmolol, and their combination for blunting the haemodynamic responses during rapid-sequence induction.

The purpose of this randomized, double-blind study was to compare the ability of a combination of fentanyl and esmolol to blunt the haemodynamic effects of intubation with that of either agent alone. Patients received fentanyl or saline four minutes before, and esmolol or saline two minutes before rapid-sequence induction of anaesthesia. The F2 group (n = 24) received fentanyl 2 micrograms.kg-1, the E2 group (n = 24) received esmolol 2 mg.kg-1, the F2/E2 group (n = 25) received a combination of fentanyl 2 micrograms.kg-1 and esmolol 2 mg.kg-1, and the F5 group (n = 26) received fentanyl 5 micrograms.kg-1. Following tracheal intubation, the maximum percent change from baseline heart rate was less in the F2/E2 and F5 groups (12% and 16% respectively) than in the E2 group (34%)(P < 0.05). The maximum percent changes from baseline systolic blood pressure in the F2/E2 and F5 groups (15% and 6% respectively) were less than in the F2 and E2 groups (24% and 33% respectively) (P < 0.05). The combination of a low dose of fentanyl and esmolol provides an alternative to a higher dose of fentanyl for blunting the haemodynamic responses to laryngoscopy and tracheal intubation during rapid-sequence induction in healthy patients.

Adrenergic beta-Antagonists↗
PubMed1992

Topographic mapping of the cutaneous microcirculation using two outputs of laser-Doppler flowmetry: flux and the concentration of moving blood cells.

Using a "needle" probe in a template probe holder, we measured the flux and the concentration of moving red blood cell (CMBC) outputs from a Perimed (PF2B) laser-Doppler instrument at 1-mm2 contiguous sites in a 8 x 8-mm area on the flexor forearm of three subjects. Using the means of the flux and CMBC recorded at each spot, a topographic contour map was constructed for each of these parameters. Viewing the two maps together, sites with four different combinations of flux and CMBC could be identified. Trephine biopsies (2 mm) of three representative sites in each subject were performed and the upper plexus was reconstructed in 3 dimensions from serial sections. High flux/high-to-medium CMBC sites were found over the spot where the ascending arterioles entered the upper plexus. Medium flux/medium-to-low CMBC sites and low flux/medium CMBC sites were found in the peripheral part of the vascular unit that was fed by the ascending arteriole. The low flux/low CMBC sites were relatively avascular zones. Video imaging of the upper plexus in the forearm showed the same overall vascular pattern as the contour maps. The highest flux and CMBC signals were recorded when horizontally oriented vessels were present in the upper third of the plexus (400-650 microns below the stratum corneum). Topographic mapping will allow one to selectively identify different microvascular areas in the skin for physiological studies.

Adult↗
PubMed1992

Accelographic train-of-four at near-threshold currents.

The authors evaluated train-of-four (TOF) fade, as quantified by accelography, in response to neurostimulation at currents ranging from 10 to 60 mA. This was done to determine the range of currents over which measurements of fade remain consistent. In 31 patients (ASA Physical Status 1,2, and 3), anesthesia was induced with fentanyl, midazolam, and thiopental and was maintained with isoflurane and 66% nitrous oxide in oxygen. Surface stimulating electrodes were placed over the ulnar nerve, and an acceleration transducer was placed on the thumb. Succinylcholine was administered to facilitate tracheal intubation; after neuromuscular recovery, a bolus of vecuronium (0.01-0.05 mg.kg-1) and an infusion (0.25-1.5 micrograms.kg-1.min-1) were administered. After documentation of a stable TOF ratio, accelographic TOF responses were quantified in response to 200-microseconds stimulation at 10, 15, 20, 30, 40, 50, and 60 mA, in random order. A total of 95 data sets were collected at different depths of blockade. The TOF ratios maintained intercurrent consistency (P = not significant by nonparametric repeated measures analysis of variance), except at currents near the fourth-twitch (T4) threshold current. This inconsistency was eliminated by testing at greater than or equal to 10 mA above threshold. TOF ratios obtained at 10 mA above T4 threshold correlated highly with those at 60 mA (Spearman r value = 0.94). The authors conclude that the TOF ratio is consistent over a wide range of stimulating currents and that testing with submaximal currents can be performed reliably at greater than or equal to 10 mA above the T4 threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Transdermal fentanyl for postoperative pain management in patients recovering from abdominal gynecologic surgery.

The current placebo-controlled double-blinded study was undertaken to assess the safety and efficacy, as well as the potential clinical role, of the transdermal therapeutic system (TTS) of fentanyl delivery in the postoperative setting. TTS patches releasing 25 micrograms.h-1 or 50 micrograms.h-1 or placebo were applied to 95 women 1 h before abdominal gynecologic surgery during general anesthesia. Postoperatively, patients self-administered intravenous morphine as required using patient-controlled analgesia with a 1-mg incremental dose and a 6-min lockout interval. Each was assessed upon admission to the postanesthesia care unit and at intervals over the following 72 h with respect to vital signs, visual analogue scale pain and satisfaction scores, side effects, and cumulative morphine use. Data were analyzed using analysis of variance, Kruskal-Wallis, and chi-square. P less than 0.05 was considered significant. There were no demographic differences among groups. Beginning 32 h after TTS application, a statistically significant morphine-sparing effect was seen with the 50 micrograms.h-1 patch. There were no significant differences among groups with regard to visual analogue scale pain scores at rest, patient satisfaction, or the incidence of side effects; a significant reduction in pain upon movement was noted at 24 h in patients treated with TTS 50 micrograms.h-1. This finding constituted the only benefit noted with this form of analgesic therapy in the present investigation.

Abdomen↗
PubMed1992

Tetanus-induced changes in apparent recovery after bolus doses of atracurium or vecuronium.

The current study evaluated the duration and magnitude of post-tetanic effects in 56 patients recovering from a bolus dose of nondepolarizing relaxant to assess the impact of tetanus on monitoring in a common clinical setting. After induction of general anesthesia (thiopental, fentanyl, oxygen, nitrous oxide, and isoflurane), a baseline response to train-of-four (TOF) stimulation was recorded using an adductor pollicis force transducer, and the ratio of the fourth response (T4) to the first (T1) was calculated. Patients then received a bolus dose of either atracurium 0.50 mg.kg-1 (n = 28) or vecuronium 0.10 mg.kg-1 (n = 28). TOF was recorded at 12-s intervals between 25% and 75% recovery of T1 (time25-75%, first data set); then, block was reestablished with the same agent (atracurium 0.10 or vecuronium 0.02 mg.kg-1), and monitoring of time25-75% was repeated (second data set). Subjects were randomized such that none, one, or both sets had TOF monitoring interrupted by a 5-s, 50-Hz tetanic stimulus at 50% recovery (TET). For each drug, 7 patients were assigned to each of the four possible sequences: no tetanus (NOTET) set followed by NOTET set; NOTET-TET; TET-NOTET; and TET-TET. After either drug, the TET data sets demonstrated significant acceleration of recovery of T1 from 50% to 75% (time50-75%) of its baseline height (P less than 0.05 by paired t test). After atracurium, time50-75% was shortened by the tetanic stimulation from a control of 6.3 +/- 1.1 to 5.0 +/- 1.3 min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Venous engorged tissue flaps treated with medicinal leeches.

We evaluated the ability of leeches to improve the tolerance of pedicle flaps to periods of venous congestion. Axial pedicle flaps were created on 14 rabbit ears; the venous circulation of each flap was compromised with a suture ligature. Medicinal leeches were applied to seven flaps; the other seven flaps were untreated. Tissue viability was assessed by both clinical examination and fluorometric analysis of fluorescein dye delivery. Leech-treated flaps showed poorer reperfusion than untreated flaps. No statistically significant difference was found in comparing the two groups.

Animals↗
PubMed1992

Metoclopramide-enhanced analgesia for prostaglandin-induced termination of pregnancy.

We previously determined that a single dose of metoclopramide could significantly reduce the patient-controlled analgesia (PCA) morphine requirements of women undergoing prostaglandin-induced termination of pregnancy. In the present study, we evaluated whether repeated doses of metoclopramide would further reduce pain and accelerate expulsion of the fetus. After intraamnionic injection of prostaglandin, patients were randomly allocated to receive either 10 mg of intravenous metoclopramide (n = 17) or saline (n = 15), concurrent with the initiation of PCA. A second, identical dose was administered 4 h later. Data included visual analogue scale scores for pain 45 min after each administration of metoclopramide or saline and visual analogue scale and sedation scores every 2 h for the first 10 h, amount of morphine delivered by PCA pump, time of fetal and placental passage, and hospital discharge. Metoclopramide-treated patients experienced significantly earlier fetal and placental passage (P < 0.05). This was associated with a 66% reduction in PCA morphine received by the time of fetal delivery (P < 0.05). In addition, patients in the metoclopramide group were discharged from the hospital significantly sooner (P < 0.05). This difference included fewer second-day hospital stays (P < 0.05). Visual analogue scale scores measured 45 min after each infusion of the study agent were reduced from baseline in the metoclopramide group only (P < 0.05). No significant intergroup differences were noted with respect to pain or interval morphine usage. We conclude that repeated doses of metoclopramide significantly reduce the duration of induced labor and therefore the total PCA morphine requirements.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Induced↗
PubMed1992

Intravenous cocaine challenges during desipramine maintenance.

Intravenous challenges with placebo and cocaine doses ranging from 0.125 to 0.5 mg/kg were administered to five subjects using a within subjects design during placebo and active desipramine (DMI) maintenance at a fixed dose of 150 mg daily for at least 10 days. The "high" reported after cocaine infusion was not altered by DMI, but "desire for cocaine" after a single dose was attenuated. Together with the results of clinical trials of DMI for cocaine abuse, these laboratory results suggest that DMI may reduce cocaine craving both during and between cocaine binges. Physiologically, baseline heart rate was higher on DMI, but the incremental heart rate response to cocaine was attenuated.

Adult↗
PubMed1992

Influence of promethazine on symptom-therapy scores for nausea during patient-controlled analgesia with morphine.

We assessed whether adding promethazine to the syringe containing morphine for patient-controlled analgesia (PCA) decreases nausea after gynecologic surgery. Patients were assigned randomly to receive PCA (morphine 1.5 mg, 6-min lockout interval) with or without promethazine (0.625 mg/PCA dose, providing an average of 17.6 mg/24 h). Assessments included a visual analogue scale (VAS) for nausea (0 = none, 10 = worst possible) at scheduled times, rescue therapy requirements, and a maximum symptom-therapy score that provided an aggregate assessment of nausea intensity, duration, and response to rescue therapy (0 = no nausea; 1 = mild; 2 = moderate, requiring droperidol; 3 = severe or persistent, requiring droperidol; 4 = requiring droperidol+transdermal scopolamine; 5 = unrelieved). Nausea scores on the visual analogue scale at 2, 6, 8, and 24 h and use of rescue droperidol identified no significant differences between the groups. However, symptom-therapy scores differed significantly, with median values of 0 and 2, respectively, for the promethazine-treated and control groups. We conclude that simultaneous titration of morphine and promethazine decreases nausea associated with PCA therapy; the difference may best be appreciated with use of the combined symptom-therapy score.

Adult↗
PubMed1992

Muscle flap monitoring in a rat model with a variable gain quantitative fluorometer.

A variable gain dermofluorometer with a wide range of sensitivities capable of quantifying fluorescein emission from both skin and muscle was tested in a rat latissimus dorsi island muscle flap model. Quantitative fluorometric readings directly from muscle and skin sites that did not undergo surgery were taken at intervals over 2 hours after intravenous fluorescein injection. Muscle flaps with intact pedicles gave an inflow-outflow pattern. A no-outflow pattern was seen in muscle flaps with ligated pedicle veins and a no-inflow pattern was seen in muscle flaps with ligated pedicle arteries. These patterns were similar to the flow pattern seen with quantitative fluorometric monitoring in flaps with cutaneous components. These results suggest that quantitative fluorometry may be applicable to circulation monitoring in muscle flaps.

Animals↗
PubMed1991

Assessment of residual curarization using low-current stimulation.

The present study employed train-of-four (TOF) stimulation at a current of 20 mA to assess the incidence and degree of residual neuromuscular blockade in 64 randomly selected Post Anesthesia Care Unit (PACU) patients. Group C (Control, n = 10) had received anaesthesia without nondepolarizing muscle relaxant; Group V (n = 25) had received vecuronium; and Group P (n = 29) had received pancuronium. At the end of surgery, each patient had been considered by his anaesthetist to have adequate neuromuscular function on the basis of clinical signs and tactile or visual evaluation of responses to TOF stimulation. However, upon testing in the PACU 15 min later, 45% (13 of 29) of Group P patients and 8% (2 of 25) of Group V patients had a TOF ration less than 0.70. This study indicates that residual curarization may be commonly encountered following long-acting relaxants despite qualitative intraoperative TOF monitoring. The present incidence, detected at a current of 20 mA, is consistent with previous reports which employed supramaximal TOF stimulation. We conclude that despite intraoperative monitoring, residual curarization following long-acting nondepolarizing agents is common and that it may be detected with TOF at a low stimulating current (20 mA).

Adult↗
PubMed1991

Elevated intravesical pressure causes arterial hypoperfusion in canine colocystoplasty: a fluorometric assessment.

Since 1988 there have been 15 reported cases of late, spontaneously ruptured intestinal cystoplasties at bowel sites remote from the anastomosis. Ischemic necrosis has been suggested as a possible etiology. We examined this hypothesis by quantifying the uptake of intravascular fluorescein in the augmented bowel of adult mongrel canines. There was a statistically significant decrease in fluorescein uptake at high intravesical pressures, which appeared to be most pronounced at the antimesenteric border. This laboratory study supports a recent clinical report of histological changes pathognomonic for chronic ischemia in the augmented bowel of patients with spontaneous rupture.

Anastomosis, Surgical↗
PubMed1991

Effect of tetanus on subsequent neuromuscular monitoring in patients receiving vecuronium.

The current study evaluated the effects of tetanic stimulation on neuromuscular responses to serial train-of-four (TOF) and double-burst stimulation (DBS). For TOF monitoring (n = 13), a degree of neuromuscular blockade was achieved with an intravenous vecuronium infusion such that the ratio of fourth twitch (T4) to first twitch (T1), T4/T1, was stable at a value between 0.1 and 0.7. Four seconds after a 5-s, 50-Hz tetanic stimulus was delivered, TOF monitoring was resumed at 10-s intervals. Significant changes were noted for T1, T4, and T4/T1, with median increases of 38, 250, and 93%, respectively. The median times for T1, T4, and T4/T1 to return to within 10% of their pretetanic (baseline) values were 34, 43, and 34 s, respectively (P = nonsignificant [NS] among times to recovery). A 100-Hz tetanic stimulus induced 50, 300, and 178% median increases of T1, T4, and T4/T1, while corresponding values for recovery times were 53, 73, and 54 s. For DBS monitoring (n = 14), tetanic stimulation (50-Hz, 5-s) induced 38, 300, and 153% median increases of the DBS3,3 parameters (first response [D1], second response [D2], and their ratio [D2 not equal to D1], respectively). The posttetanic effects on D1, D2, and D2/D1 persisted for 43, 66, and 46 s, respectively. For DBS3,2, median posttetanic (50-Hz, 5-s) increases were 41, 275, and 176%, while corresponding times to recovery were 43, 43, and 43 s. Although the data indicate that the posttetanic percent increase was at least 10 times larger at greater degrees of blockade (T4/T1 = 0.1) than at lesser degrees (T4/T1 = 0.7), all T4/T1 and D2/D1 ratios returned to within 10% of baseline in 125 s or less after 5-s tetanic stimulation.

Adult↗