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Biomedical subjects

T Duke

Publications and source records attributed to T Duke.

At least 55 records · Page 3Linked to original sources
PubMed1994

A comparison of systolic blood pressure measurement obtained using a pulse oximeter, and direct systolic pressure measurement in anesthetized sows.

Systolic blood pressure measurement obtained with a pulse oximeter has been compared to values obtained by other indirect methods in man. Direct pressure measurement is subject to less error than indirect techniques. This study was designed to compare systolic pressure values obtained using a pulse oximeter, with values obtained by direct arterial pressure measurement. The pulse oximeter waveform was used as an indication of perfusion. A blood pressure cuff was applied proximal to the pulse oximeter probe. The cuff was inflated until the oximeter waveform disappeared, this value was recorded as the systolic pressure at the disappearance of the waveform (SPD). The cuff was inflated to a pressure > 200 mmHg, then gradually deflated until the waveform reappeared, this value was recorded as the systolic pressure at reappearance of the waveform (SPR). The average of the two values, SPD and SPR, was calculated and recorded as SPA. The study was performed in sows (n = 21) undergoing cesarean section under epidural anesthesia and IV sedation. A total of 280 measurements were made of SPD, SPR and SPA. Regression analysis of SPA and direct measurement revealed a correlation coefficient (r) of 0.81. Calculation of mean difference (bias) and standard deviation of the bias (precision) for direct pressure--SPA revealed a value of 1.3 +/- 12.1. When compared with direct measurement, the correlation of this technique was similar to that recorded for other indirect techniques used in small animals. This indicates that this technique would be useful for following systolic pressure trends.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1993

DNA electrophoresis in polymer solutions: Ogston sieving, reptation and constraint release.

The electrophoresis of long polyelectrolytes is considered theoretically, with special attention to duplex DNA. We first discuss quantitative approaches to determine unambiguously the entanglement properties of polymer solutions. Following an idea proposed by Grossman and Soane, we then assume that the "mesh" size of the solution plays the role of a dynamic "pore size" in order to apply theories for gel electrophoresis. In the framework of the Ogston model, we predict that duplex DNA up to 1 kb or more should be separable in dilute (i.e. nonentangled) solutions of high molecular weight polymers. In an entangled solution, and for DNA larger than the pore size, we use a recently developed fluctuation-reptation model to predict the range of sizes in which separation should be possible as a function of electric field E and pore size zeta b. For zeta b larger than the Kuhn length of DNA, we predict a separation up to a size N*scaling as E-1 zeta b-1. For zeta b smaller than the Kuhn length, two different regimes are expected. For small electric fields (typically of the order of 10 V/cm), N*should be proportional to E-1 zeta b-3/2, whereas for high electric fields such as encountered in capillary electrophoresis, we expect that N*is proportional to E-2/5 zeta b-12/5. These predictions are qualitatively different from earlier ones. Finally, we demonstrate that the finite lifetime of the "pores" in an entangled solution (as opposed to a gel) may lead to a new migration mechanism by constraint release, which is not size-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed1993

Neonatal alloimmune thrombocytopenia. A case report and a review of the literature.

A 32-year-old woman in her third pregnancy underwent fetal blood sampling because of a previous child with neonatal thrombocytopenia. At 33 weeks' gestation, fetal thrombocytopenia was diagnosed. Treatment was instituted antenatally with serial fetal platelet transfusions and corticosteroid therapy. Delivery was by Caesarean section at 37 weeks' gestation. Neonatal treatment included further platelet transfusion and immunoglobulin infusion. Recovery of the neonate was complete on discharge from hospital 10 days after birth. The aetiology, diagnosis, clinical presentations and therapeutic options in cases of alloimmune thrombocytopenia are discussed.

Adult↗
PubMed1991

Asthma in the emergency department: impact of a protocol on optimizing therapy.

The objective of this study was to evaluate the impact of a simple educational intervention on the prescribing habits of internal medicine residents in the treatment of acute asthma in a busy emergency department (ED). Prescribing habits for 16 residents were documented for 4 months. The first 2 months served as a control period during which eight residents managed asthma patients without the benefit of any specific educational intervention beyond standard department protocols. A total of 129 patients treated by the residents during this initial phase were assessed. During the second 2-month period, a 10-minute verbal presentation and explicit written treatment protocol were provided to another eight residents, and their treatment of 83 patients was covertly evaluated. Increased prescribing of desired therapy was significantly improved in every area except that of prescribing an inhaled steroid metered dose inhaler for use as a discharge medication. The 10-minute verbal presentation given in conjunction with a three-page handout was found to be highly effective for eliciting improvement in treatment practices during short clinical rotations. The duration of this effect beyond each rotation is unknown. This educational intervention should be presented by the ED medical director, clinical pharmacist, or other appropriate clinician in virtually any ED as quality of patient care can be dramatically improved.

Acute Disease↗
PubMedDate not supplied

One-lung versus two-lung ventilation in the closed-chest anesthetized dog: a comparison of cardiopulmonary parameters.

OBJECTIVE: To evaluate cardiopulmonary effects of one-lung ventilation (OLV) versus two-lung ventilation (TLV) in closed-chest anesthetized dogs. STUDY DESIGN: Controlled, randomized experiment. ANIMALS: Fourteen, 2- to 7-year-old adult dogs, weighing 23 +/- 6 kg. METHODS: The dogs were anesthetized with acepromazine, morphine, thiopental, and halothane in oxygen, ventilated, and paralyzed with vecuronium. Tidal volume was 10 mL/kg. Respiratory rate was set to maintain end-tidal CO2 (ETCO2) at 40 +/- 2 mm Hg before instrumentation then not changed. The left bronchus of 7 dogs was obstructed with a Univent bronchial blocker (Fuji Systems Corp, Tokyo, Japan). Blood gas analysis and hemodynamic measurements were taken at predetermined intervals for 1 hour in the TLV group and at baseline and following bronchial obstruction in the OLV group. RESULTS: Shunt fraction was not significantly different between groups, but in OLV shunt increased from baseline at 5 minutes. Arterial oxygen (PaO2) decreased after baseline in OLV compared with TLV. Arterial carbon dioxide (PaCO2) increased with OLV and decreased with TLV. In OLV, systemic vascular resistance was variable and decreased compared with TLV. Cardiac index increased over time in both groups but was not affected by treatment. Heart rate, mean arterial pressure, and diastolic arterial pressure increased with OLV compared with TLV but did not change over time. CONCLUSION: This study shows that OLV statistically decreases oxygen tension and transiently increases shunt fraction, but with 100% O2 it appears to be a feasible procedure with minimal cardiopulmonary side effects in healthy dogs. CLINICAL RELEVANCE: OLV is a feasible procedure in anesthetized dogs to better facilitate thoracic procedures such as bronchopleural fistula repair and thoracoscopy.

Anesthesia, General↗
PubMedDate not supplied

The analgesic effects of administering fentanyl or medetomidine in the lumbosacral epidural space of cats.

The analgesic effects of fentanyl (4 micrograms/kg) and medetomidine (10 micrograms/kg) in 1 mL saline injected epidurally were measured in 15 cats. The response to an electrical cutaneous stimulus from a constant current generator was used as the index of analgesia. The stimulus was applied to a forelimb before epidural injection, and at 15, 30, 60, 90, 120, 180, 240, and 300 minutes post-injection (PI). The hindlimb was tested 5 minutes later. One mL saline only was used to control for volume of injection and saline. Medetomidine significantly increased the pain threshold for the hindlimb at 20 to 245 minutes PI compared with the preinjection level. Fentanyl significantly increased the pain threshold at 20 minutes PI only compared with preinjection levels. Medetomidine significantly increased the pain threshold of the forelimb at 15 to 120 minutes PI compared with the preinjection levels. Fentanyl did not significantly increase the pain threshold of the forelimb. Administration of medetomidine produced emesis in 12 of 15 cats in an average of 6.4 minutes PI (range, 3 to 11 minutes) and mild sedation in all cats. Injection of fentanyl produced no visible side effects in any of the cats.

Analgesia, Epidural↗
PubMedDate not supplied

The cardiopulmonary effects of placing fentanyl or medetomidine in the lumbosacral epidural space of isoflurane-anesthetized cats.

The cardiopulmonary effects of fentanyl (4 micrograms/kg) or medetomidine (10 micrograms/kg) in saline injected epidurally were measured for 2 hours in 15 isoflurane (2.4%)-anesthetized cats. One milliliter of saline without drug was used to control for saline and volume of injection. Baseline was taken as preinjection time 0. Medetomidine significantly increased (P < .05) mean arterial blood pressure (MAP) 5 to 20 minutes postinjection (PI) compared with baseline. MAP significantly decreased 30 to 120 minutes PI compared with baseline. Fentanyl significantly decreased MAP 5 to 120 minutes PI compared with baseline. Heart rate and respiratory rates significantly decreased in the medetomidine and fentanyl groups 5 to 120 minutes PI compared with baseline. Arterial pCO2 significantly increased while arterial pH significantly decreased 15 to 120 minutes PI in the fentanyl and medetomidine groups compared with baseline. Blood bicarbonate concentration significantly increased 90 to 120 minutes PI in the medetomidine group compared with baseline.

Analgesia, Epidural↗
PubMedDate not supplied

Cardiopulmonary effects of using carbon dioxide for laparoscopic surgery in dogs.

Cardiopulmonary effects of laparoscopic surgery were investigated in five crossbred dogs (21 +/- 1.9 kg). Premedicated dogs were anesthetized with thiopental and maintained with halothane at 1.5 times minimum alveolar concentration in oxygen. Controlled ventilation maintained partial pressure of end-tidal CO2 at 40 +/- 2 mm Hg. Vecuronium was used for skeletal muscle relaxation. After instrumentation and stabilization, baseline measurements were made of cardiac output (thermodilution technique), mean systemic, mean pulmonary arterial and pulmonary wedge pressures, heart rate, saphenous vein and central venous pressures, and minute ventilation. Baseline arterial and mixed venous blood samples were drawn for analysis of pH, PaO2, PaCO2, PvO2, PvCO2, and bicarbonate concentrations. Systemic and pulmonary vascular resistances, oxygen delivery and consumption, shunt fraction, and dead space ventilation were calculated using standard formulas. Abdominal insufflation using CO2 to a pressure of 15 mm Hg for 180 minutes resulted in significant (P < .05) increases in heart rate (15 to 180 minutes), minute ventilation (75 to 135 minutes), and saphenous vein pressure (15 to 180 minutes), and decreases in pH (60 to 180 minutes) and PaO2 (60 to 180 minutes). For 30 minutes after desufflation, there was a significant decrease in PaO2, and increases in cardiac output, O2 delivery, and heart rate, compared with baseline. There was a significant increase in shunt fraction and decrease in pH at 15 minutes after desufflation only. The changes were within physiologically acceptable limits in these healthy, ventilated dogs.

Abdomen↗
PubMedDate not supplied

Comparison of plasma fentanyl concentrations by using three transdermal fentanyl patch sizes in dogs.

OBJECTIVE: To compare plasma fentanyl concentrations attained after the application of three transdermal fentanyl patch sizes (50, 75, and 100 micrograms/hour) in dogs. DESIGN: Repeated Latin square controlled study. ANIMALS: Six intact, mixed-breed adult dogs (2 males, 4 females) weighing 19.9 +/- 3.4 kg. METHODS: Each dog was randomly assigned to receive each of three treatments: 50 (P50), 75 (P75), or 100 (P100) micrograms/hour transdermal patches. Patches were left in place for 72 hours. Jugular venous blood was collected at 1, 2, 4, 8, 12, 24, 36, 48, 60, and 72 hours after patch application and for 1, 2, 4, 8, and 12 hours after patch removal. Plasma fentanyl concentrations were measured using a radioimmunoassay technique. After a 96-hour washout period, each dog was moved to another treatment group and received a different patch size. RESULTS: The following results were obtained (mean +/- SD): average plasma fentanyl concentration from 24 to 72 hours, 0.7 +/- 0.2 ng/mL (P50), 1.4 +/- 0.5 ng/mL (P75), 1.2 +/- 0.5 ng/mL (P100); the total area under the concentration versus time curve (0 hours to infinity), 46 +/- 12.2 ng/h/mL (P50), 101.2 +/- 41.4 ng/h/mL (P75), 80.4 +/- 38.3 ng/h/mL (P100); and the apparent elimination half-life, 3.6 +/- 1.2 hours (P50), 3.4 +/- 2.7 hours (P75), and 2.5 +/- 2.0 hours (P100). There was a high degree of variability in plasma fentanyl concentrations achieved. Plasma fentanyl concentrations declined rapidly after patch removal. CONCLUSIONS: The attainment of steady-state plasma concentrations takes up to 24 hours, and there is a great deal of variability in the final concentrations reached in different individuals. In this study, the 100 micrograms/hour patches did not provide statistically increased plasma concentrations when compared with the 50 micrograms/hour patches. CLINICAL RELEVANCE: Because of the interindividual and intraindividual variation in plasma fentanyl concentrations, patches should be applied 24 hours before the anticipated time that analgesia will be required. Adequacy of analgesia and potentially deleterious side effects, such as sedation and respiratory depression, should be monitored while the patches are in place. Skin reactions may occur, and the patches should be removed if such skin irritation is seen. After the patch is removed, it is expected that analgesia will wane rapidly because of the brief elimination half-life.

Administration, Cutaneous↗
PubMedDate not supplied

Thoracoscopic versus open partial pericardectomy in dogs: comparison of postoperative pain and morbidity.

OBJECTIVE: To evaluate postoperative pain and morbidity in dogs undergoing open thoracotomy and partial pericardectomy versus thoracoscopic pericardectomy. STUDY DESIGN: Research study in normal dogs. ANIMALS OR SAMPLE POPULATION: Fourteen mixed breed healthy dogs. METHODS: Seven dogs had a partial pericardectomy through a standard left lateral thoracotomy at the fifth intercostal space. The remaining seven dogs underwent selective lung ventilation and thoracoscopic partial pericardectomy. Surgery sites in both groups were bandaged and each dog received a single postoperative dose of morphine (0.2 mg/kg, intramuscularly [i.m.]). Postoperative pain was evaluated using a standard pain score table at 1, 5, 9, 17, 29, and 53 hours after surgery. Dogs receiving a pain score of six or greater received an additional dose of morphine. At each observation point, blood samples were taken to measure blood glucose and plasma cortisol concentrations. Pain scores, blood glucose, and plasma cortisol concentrations were compared between the two groups using two-way ANOVA. RESULTS: Blood glucose concentrations, plasma cortisol concentrations, and pain scores were significantly different between the two groups, with the thoracotomy dogs having higher values at 1, 5, and 9 hours postoperatively. Three of the open thoracotomy dogs required additional analgesia after the initial dose of morphine. In addition, two dogs that underwent open thoracotomy were lame in the left forelimb and two others developed dehiscence of their wounds. CONCLUSIONS AND CLINICAL RELEVANCE: Thoracoscopic partial pericardectomy has several advantages over open partial pericardectomy including decreased postoperative pain, fewer wound complications, and more rapid return to function.

Animals↗
PubMedDate not supplied

Excitatory movements in a dog following propofol anesthesia.

A two-year-old, neutered male Labrador retriever was anesthetized with intravenous propofol for bronchoscopy to remove a bronchial foreign body. The dog previously had been diagnosed with idiopathic epilepsy. During anesthetic recovery, the dog exhibited excitatory movements characterized by forelimb extensor rigidity, opisthotonos, generalized tremors, paddling, horizontal nystagmus, and facial twitching. Intravenous administration of pentobarbital temporarily stopped the motor activity. The excitatory movements persisted for 20 hours. The dog went on to recover completely, although he remained an epileptic, having one brief, generalized grand mal seizure every three-to-four months.

Anesthetics, Intravenous↗
PubMedDate not supplied

Congenital syphilis at Goroka Base Hospital: incidence, clinical features and risk factors for mortality.

A prospective study of all cases of congenitally acquired syphilis diagnosed at Goroka Base Hospital was conducted between January 1998 and December 1999. 67 affected neonates and children were seen, of whom 19 died during the first admission and 3 died during the period of follow-up. Congenital syphilis caused 5.5% of 994 neonatal admissions, but 22% of all neonatal deaths. The major risk factor for death in affected babies was low birthweight. A birthweight of less than 2 kg had an odds ratio for death of 30.0 (95% confidence interval 6.90-131.1). During the time of the study 5385 women attended antenatal care at Goroka Base Hospital, of whom 382 had both positive VDRL and TPHA tests. The incidence of syphilis in women attending antenatal care was 7.1%. Syphilis is a major cause of neonatal mortality and morbidity and a major cause of morbidity among women of childbearing age in the Eastern Highlands Province. Current antenatal screening is inadequate, covering less than 30% of pregnant women. New ways to extend syphilis screening and treatment to all affected pregnant women are urgently required and must be formally assessed.

Birth Weight↗