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Biomedical subjects

D G Silverman

Publications and source records attributed to D G Silverman.

At least 109 records · Page 6Linked to original sources
PubMed1983

Quantification of fluorescein distribution to strangulated rat ileum.

Following various periods of strangulation, the fates of intestinal segments were predicted by standard clinical criteria and visual (Wood's lamp) and fluorometric (perfusion fluorometer) assessment of fluorescein distribution. With fluorometry, a means of quantifying fluorescence transmitted via a fiberoptic light guide, the delivery and removal of fluorescein were monitored and analyzed. If either was restricted significantly, tissue death was predicted. Analysis of computerized graphic patterns or simple interpretation of fluorometric readings at two time points predicted tissue fate with 98% accuracy and a 93% negative predictive value. Wood's lamp evaluation had only a 53% accuracy and a 33% negative predictive value, while standard clinical criteria had an 81% accuracy and a 53% negative predictive value. Fluorescein leakage in segments which suffered significant endothelial damage provided staining patterns that incorrectly suggested viability. By monitoring elimination as well as uptake of dye, fluorometry provided much greater discrimination than did Wood's lamp inspection in this setting. In addition, fluorometry was readily repeatable within minutes, as fluorescence remaining from a previous injection could be subtracted from new, postinjection values.

Animals↗
PubMed1983

Evaluation of the burn wound with perfusion fluorometry.

Determination of depth of burn injury using vital dyes has been unsatisfactory. The present study evaluated the ability of the fiberoptic perfusion fluorometer to assess the depth of burn in the early postburn period. Sixty-three burns were examined with the fluorometer after intravenous administration of sodium fluorescein. The fluorescein kinetics were monitored for 1 hour within the first 48 hours and again between the third and sixth days postburn. The rate of fluorescein uptake and burn wound fluorescence was determined and compared to that of normal unburned skin. Depth of burn was confirmed by biopsy and healing characteristics. Fluorometric analysis during both study periods consistently distinguished between partial-thickness and full-thickness burns. Partial-thickness burns uniformly exhibited fluorescence within 10 minutes; full-thickness burns showed nil fluorescence. None of the patients experienced a change in skin color or complications from the small dose of fluorescein given.

Burns↗
PubMed1983

Fluorometric assessment of skin flap viability in the rat: effect of radiation therapy.

The fluorescein test is widely used to assess perfusion in skin flaps but tends to underestimate skin viability when visual inspection under ultraviolet light is employed. Fiberoptic dermofluorometry, which has recently been introduced, more accurately assesses fluorescein distribution in skin flaps than does visual inspection. Viability of the back flap in rats receiving ionizing radiation was evaluated by dermofluorometry. This technique was highly accurate in predicting viability and has great applicability for studying blood flow in irradiated tissues.

Animals↗
PubMed1983

Monitoring free flap perfusion by serial fluorometry.

An efficient method to evaluate the patency of microvascular anastomoses and to predict flap viability is crucial when free flaps are used in reconstructive surgery. We report a study of 60 neurovascular island flaps in rats where the nutrient artery and/or vein were transected and anastomosed. Fluorescein dye was injected immediately after anastomosis, and the uptake and elimination of dye were quantified at 5-minute intervals with the fiberoptic perfusion fluorometer. Analysis of dye delivery clearly identified six hypofluorescent flaps presumed to be ischemic. In five of these flaps, revision was attempted. Three evidenced improved fluorescein uptake and elimination on reinjection of dye. These flaps survived, whereas the other two necrosed. Of the 54 flaps deemed patent after the first injection, two evidenced poor fluorescence on reinjection 3 hours later. These flaps necrosed and evidenced venous thrombosis (which probably occurred during the 3 hours between the first and second injections). Fiberoptic fluorometry can be employed to assess a free flap immediately after vascular anastomosis and throughout the critical hours postoperatively. Assessment of uptake and elimination after single or serial injections reflects flap perfusion and predicts viability with a high degree of accuracy.

Animals↗
PubMed1983

Fiberoptic fluorometer for skin flap assessment.

The fiberoptic fluorometer permits quantitative measurement of fluorescence after intravenous administration of fluorescein. Accurate assessment of tissue fluorescence can be made at any time after the injection, and both uptake and elimination of fluorescein can be followed. The instrument provides instantaneous digital readout of the fluorescence measured in dye fluorescence (DF) units and an index predictive of viability called the dye fluorescence index (DFI). The unit is portable, can be sterilized for operating room use, and can be operated by paramedical personnel with ease. We have used the instrument extensively in clinical and laboratory investigations, where it has been highly reliable in predicting survival and necrosis of a wide variety of flaps. Little or no operating time is added, and serial, low-dose fluorescein injections may be used to monitor a flap in the recovery room or at the bedside in the early postoperative period.

Fiber Optic Technology↗
PubMed1982

Altered skin flap survival and fluorescein kinetics with hemodilution.

Isovolemic hemodilution is known to reduce blood viscosity. Reduction of either the blood cell concentration or the serum total protein has been found to improve blood flow and ultimate survival of skin flaps. Nutritive blood flow and tissue survival were examined in dorsal pedicle skin flaps in three groups of rats at three hematocrit levels--44% (controls), 31%, and 19%. After hemodilution by phlebotomy and crystalloid replacement, the dye kinetics of intravenously administered fluorescein were measured with the fiberoptic perfusion fluorometer. Skin flap survival at the different hematocrits were also examined. Hematocrits and serum total protein were measured before and after hemodilution and the elevation of the flap. The rate of fluorescein elimination and ultimate flap survival were significantly augmented in the two hemodiluted groups. The maximum benefit was seen in the group of animals hemodiluted to 19%. However, significant improvement in blood flow and skin flap survival was noted in the group of animals that were hemodiluted to a more clinically acceptable level (31%). The decreases in serum total protein following flap elevation did differ among the groups. This study supports the hypothesis that isovolemic hemodilution may be a valuable technique for salvaging marginally ischemic tissues.

Animals↗
PubMed1981

Monitoring tissue elimination of fluorescein with the perfusion fluorometer: a new method to assess capillary blood flow.

Visual assessment of tissue staining after intravenous fluorescein is a common technique for predicting viability of questionably perfused tissue. The development of the perfusion fluorometer has permitted quantification of tissue fluorescein, providing increased precision. This study employed this instrument to calculate fluorescein elimination from rats with and without raised dorsal pedicle flaps. Control animals exhibited homogeneous patterns of fluorescein elimination consistent with first-order kinetics. Elimination in experimental animals was assessed after the animals received full back skin flaps with the cephalad pedicle remaining intact. Three distinct patterns of elimination were noted in each flap. In the cephalad portion, elimination was similar to control. At the caudad end, no elimination was noted. Midflap, fluorescein was eliminated slowly. These elimination patterns predicted ultimate viability 14 days postoperatively, as they correspond to viable, dystrophic, and transitional sections, respectively (P less than 0.001). We conclude that perfusion fluorometry can assess capillary flow in healthy and ischemic tissue by documenting elimination as well as delivery of fluorescein.

Animals↗
PubMed1980

Quantification of tissue fluorescein delivery and prediction of flap viability with the fiberoptic dermofluorometer.

Quantitative fluorescence assessment with the fiberoptic dermofluorometer has been introduced to overcome the inadequacies of ultraviolet inspection following intravenous administration of fluorescein. Initial applications in the pedicle flap of the rat have indicated that this method can predict flap viability with reproducible precision and accuracy. This minimally invasive technique should be of considerable assistance to the evaluation of hypoperfused states in laboratory and clinical situations.

Animals↗
PubMed1975

Brief hypoxia-ischemia initially damages cerebral neurons.

Rats were studied during cerebral hypoxic ischemia to determine whether neurons or blood vessels suffered the first damage. Ten or more minutes of unilateral carotid artery occlusion combined with systemic hypoxemia (PaO-2, 21 mm Hg) produced neuronal but not vascular damage in the ipsilateral cerebral hemispheres of 18 of 29 rats (62%); two and five minute stresses caused no visible neuronal abnormalities. The longer exposures produced more widespread damage, and neuronal loss and gliomesodermal reaction were evident after prolonged survival. Early neuronal changes correlated with abnormalities of motor behavior (P less than .005). Despite neuronal damage that was sometimes extensive, vascular no-reflow developed in only one of 24 animals after 20 and 30 minutes of hypoxia-ischemia. Production of neuronal and neurological abnormalities in the absence of hypotension or vascular no-reflow indicates that hypoxia-ischemia initially damaged cerebral neurons.

Anesthesia, Inhalation↗
PubMedDate not supplied

Temporal correlation of succinylcholine-induced fasciculations to loss of twitch response at different stimulating frequencies.

STUDY OBJECTIVE: The present study was undertaken to determine the time courses of succinylcholine-induced fasciculations and adductor pollicis single-twitch responses at two stimulating frequencies. DESIGN: A prospective, randomized study. SETTING: The main operating room of a university teaching hospital. PATIENTS: Forty-four patients undergoing general anesthesia and requiring tracheal intubation. INTERVENTIONS: In 22 patients, anesthesia was induced with thiopental sodium, fentanyl, and midazolam and maintained with 70% nitrous oxide in oxygen prior to the administration of succinylcholine 1 mg/kg. In another 22 patients, end-tidal isoflurane 0.75% to 1% was included in the induction regimen. Patients in each group were randomly assigned to receive ulnar nerve stimulation at either 0.1 Hz or 1.0 Hz. MEASUREMENTS AND MAIN RESULTS: The times at which fasciculations were first noticed and no longer visible and the times to 25%, 50%, 75%, 90%, and 100% twitch depression were recorded. These times were compared for the two rates of neurostimulation. With single-twitch nerve stimulation at 1.0 Hz, 100% twitch depression occurred 6 +/- 16 seconds following the end of fasciculations, while at a stimulating frequency of 0.1 Hz, it occurred 52 +/- 32 seconds later (p less than 0.05). At the end of fasciculations, single-twitch depression of 50% or more was noted in only 19% of patients in the 0.1 Hz groups and in all patients in the 1.0 Hz groups (p less than 0.05). In the 0.1 Hz groups, 50% twitch depression occurred 19 +/- 27 seconds after the end of fasciculations, with more than three-quarters of the patients having achieved 50% twitch depression 30 seconds following the disappearance of fasciculations. The addition of isoflurane did not significantly alter any of these times. CONCLUSIONS: The data reveal that cessation of fasciculations may be an inaccurate clinical sign of the readiness for intubation and confirm that standardized methods of neurostimulation are necessary in the pharmacodynamic evaluation of neuromuscular blocking drugs. In settings where profound neuromuscular relaxation is not required, waiting at least 30 seconds beyond the disappearance of fasciculations should provide good intubating conditions.

Adolescent↗
PubMedDate not supplied

Variability of onset times within and among relaxant regimens.

STUDY OBJECTIVE: To evaluate the consistency of times to 95% twitch height depression (T95%) in groups of patients receiving identical induction and relaxant regimens. DESIGN: Prospective, noncontrolled, blinded study. SETTING: Ambulatory surgical unit at a university medical center. PATIENTS: Seventy-five ASA physical status I and II patients undergoing general endotracheal anesthesia. INTERVENTIONS: Patients received succinylcholine 1.5 mg/kg or a nondepolarizing regimen with doses ranging from approximately 1.5 to 6 times the ED95, with or without a priming dose. MEASUREMENTS AND MAIN RESULTS: For each of the eight relaxant regimens used in five or more patients, the intraregimen variability of T95% (at the adductor pollicis muscle upon ulnar stimulation at 0.1 Hz) was expressed as SD and range, and the individual data points were displayed. There was wide intraregimen variability. For each regimen, the slowest T95% was at least 73% longer than the fastest T95%. For the 16 patients receiving a priming dose plus an intubating dose 5 or more times the ED95, the median T95% was 95 seconds; however, T95% was beyond 120 seconds in 5 of the 16 cases. CONCLUSIONS: The wide variability in onset times among subjects receiving the same regimen indicates that monitoring of neuromuscular response, preferably to a relatively slow rate of neurostimulation, is essential if one elects to use moderate to high doses of atracurium and/or vecuronium for rapid-sequence induction in a patient in whom movement or coughing is unacceptable. Since onset times were not symmetrical about the mean, the magnitude and frequency of unacceptable onset times would not be fully appreciated unless the individual data points were displayed. Such information may be critical when reporting the suitability of a neuromuscular blocking drug for rapid intubation.

Adult↗
PubMedDate not supplied

The efficacy of intramuscular ketorolac in combination with intravenous PCA morphine for postoperative pain relief.

STUDY OBJECTIVE: To examine the efficacy of intramuscular (IM) ketorolac used in combination with intravenous (IV) patient-controlled analgesia (PCA) morphine for postoperative pain relief following intra-abdominal gynecologic surgery. DESIGN: Randomized, double-blind, placebo-controlled study. SETTING: Patient care unit at a university medical center. PATIENTS: Thirty-five healthy women undergoing intra-abdominal gynecologic surgery who requested postoperative PCA. INTERVENTIONS: Postoperatively, all patients received IV PCA morphine, with the PCA device programmed to deliver a maximum of 1 mg every 6 minutes (maximum of 30 mg over 4 hours). In addition, patients received one of three regimens: (1) IM saline every 6 hours; (2) IM ketorolac 30 mg while in the postanesthesia care unit (PACU), followed by 15 mg every 6 hours; or (3) IM ketorolac 60 mg while in the PACU, followed by 30 mg every 6 hours. MEASUREMENTS AND MAIN RESULTS: Patients were assessed at regular intervals. Visual analog scale (VAS) scores were used to assess analgesia and patient satisfaction with therapy. Data on morphine usage were obtained from the PCA device, and the frequency and severity of adverse effects were assessed for the presence or absence of side effects. Cumulative morphine dosages were lower (p less than 0.05) in both ketorolac groups at 12, 18, and 24 hours. VAS scores and the frequency of side effects did not differ significantly among groups. CONCLUSIONS: IM ketorolac significantly decreased PCA morphine requirements. The analgesic effects of the two drugs appear to be additive.

Adult↗
PubMedDate not supplied

Intravenous ketorolac as an adjunct to patient-controlled analgesia (PCA) for management of postgynecologic surgical pain.

STUDY OBJECTIVE: To determine whether intravenous (IV) doses of ketorolac tromethamine provide safe and effective augmentation of postsurgical analgesia for patients using IV patient-controlled analgesia (PCA) with morphine. DESIGN: Randomized, double-blind, placebo-controlled, dose-response evaluation. SETTING: Patient care unit at a university medical center. PATIENTS: 62 ASA physical status I-III females recovering from intra-abdominal gynecologic surgery with general anesthesia who requested postoperative PCA. INTERVENTIONS: Following initial pain assessment in the recovery room, patients were randomized to receive either IV saline (placebo) followed by IV saline every 6 hours (Group 1); IV ketorolac 30 mg loading dose followed by IV ketorolac 15 mg every 6 hours (Group 2); or IV ketorolac 60 mg loading dose followed by IV ketorolac 30 mg every 6 hours (Group 3). All patients were provided IV PCA, which was programmed to provide 1.2 mg of morphine with a 6-minute lockout interval. MEASUREMENTS AND MAIN RESULTS: Visual analog scale (VAS) resting pain and satisfaction scores were measured every 2 to 12 hours. Cumulative PCA with morphine and the frequency and severity of side effects also were assessed. IV ketorolac showed no clinically significant side effects. Group 2 patients experienced significant reductions in VAS resting pain scores (p < 0.05), and a trend toward decreased morphine self-administration in both active groups was noted. Group 2 and Group 3 patients reported greater satisfaction with postsurgical analgesia than Group 1 patients. (p < 0.05). CONCLUSIONS: IV ketorolac used as an analgesic adjunct provided safe and effective augmentation of PCA with morphine in patients recovering from intra-abdominal gynecologic surgery.

Adult↗
PubMedDate not supplied

Cost-effective use of operating room supplies based on the REMEDY database of recovered unused materials.

It is estimated that $200 million worth of prepared materials are discarded unused in operating rooms in the United States each year. Although some of these materials have been successfully recovered for overseas donation, they nevertheless constitute an undesirable burden on health care efficiency. This situation has prompted a reevaluation of the procedures that result in the overpreparation of surgical supplies, in the hope of reducing hospital, patient, and third-party payer expenditures. A database, which was initially developed to track the overseas donation of recovered supplies from Yale-New Haven Hospital, is now being applied to measure approaches to waste reduction. This report summarizes the application of this database to an integrated program designed to modify nursing procedures and physician prespecified supply lists.

Budgets↗
PubMedDate not supplied

The therapeutic intervention scoring system. An application to acutely ill cancer patients.

The Therapeutic Intervention Scoring System (TISS) has been introduced (Cullen DJ, Civetta JM, Briggs BA, et al: Therapeutic intervention scoring system: A method for quantitative comparison of patient care. Crit Care Med 2:57-60, 1974) at the Massachusetts General Hospital as a means of quantifying the medical and nursing care required by critically ill patients. The method has been instituted in the Intensive Care Unit of Memorial Cancer Center to evaluate its applicability to patients who develop life-threatening complications of their disease or its treatment. This is a preliminary report of the system's use in 55 consecutive patients who averaged 33.4 intervention points per day. This average compares closely with that of postcardiac surgery patients (31.8 points), the group that required the most care of all patients in the initial study. The results indicate the usefulness of this sytem in evaluating severity of illness, predicting survival, and assessing cost benefits. It has proven to be a simple and accurate method of assessment when simple and accurate method of assessment when applied to this patient population, but certain modifications seem warranted and have been suggested herein.

Acute Disease↗
PubMedDate not supplied

Clinical assessment of flap perfusion by fiberoptic fluorometry.

Perfusion fluorometry, a method which quantifies tissue fluorescence after intravenous fluorescein injection, has been highly predictive of skin flap survival in animals. It is advantageous because it is objective, simple, noninvasive, repeatable, and can be used to monitor flap perfusion constantly by following both uptake and elimination of dye. We applied this method clinically to a variety of flaps used in head and neck surgery. All flaps with good fluorometric values survived totally. Based on experience with 37 flaps, fluorometric indices have been established that accurately predict necrosis. Serial dye injections have been used to document transient flap ischemia in the early postoperative period. Representative cases illustrating the advantages of fluorometry in flap assessment are presented.

Aged↗