Cardiopulmonary and anesthetic effects of propofol in wild turkeys

OBJECTIVE: To determine safety, anesthetic variables, and cardiopulmonary effects of i.v. infusion of propofol for induction and maintenance of anesthesia in wild turkeys. ANIMALS: 10 healthy, adult wild turkeys. PROCEDURE: Anesthesia was induced by i.v. administration of propofol (5 mg/kg of body weight) over 20 seconds and was maintained for 30 minutes by constant i.v. infusion of propofol at a rate of 0.5 mg/kg/min. Heart and respiratory rates, arterial blood pressures, and arterial blood gas tensions were obtained prior to propofol administration (baseline values) and again at 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 minutes after induction of anesthesia. All birds were intubated immediately after induction of anesthesia, and end-tidal CO2 concentration was determined at the same time intervals. Supplemental oxygen was not provided. RESULTS: Apnea was observed for 10 to 30 seconds after propofol administration, which induced a decrease in heart rate; however, the changes were not significant. Compared with baseline values, respiratory rate was significantly decreased at 4 minutes after administration of propofol and thereafter. Systolic, mean, and diastolic pressures decreased over the infusion period, but the changes were not significant. Mean arterial blood pressure decreased by 30% after 15 minutes of anesthesia; end-tidal CO2 concentration increased from baseline values after 30 minutes; PO2 was significantly decreased at 5 minutes after induction and thereafter; PCO2 was significantly (P < 0.05) increased after 15 minutes of anesthesia; and arterial oxygen saturation was significantly (P < 0.05) decreased at the end of anesthesia. Two male turkeys developed severe transient hypoxemia, 1 at 5 and the other at 15 minutes after induction. Time to standing after discontinuation of propofol infusion was 11 +/- 6 minutes. Recovery was smooth and unremarkable. CONCLUSION: Propofol is an effective agent for i.v. induction and maintenance of anesthesia in wild turkeys, and is useful for short procedures or where the use of inhalational agents is contraindicated.     

Anesthesia induction for laryngeal mask insertion--comparison of propofol with midazolam and propofol with thiopental

STUDY DESIGN: Radiographs and charts of 61 patients sustaining cervical spine trauma were studied prospectively to determine the incidence of vertebral artery injuries and possible correlative factors. Statistical analysis was conducted using chi-square testing of a two-way classification system. OBJECTIVES: To elucidate the incidence of vertebral artery injuries associated with cervical spine trauma, and to determine the value of various factors in predicting the existence of a vertebral artery injury. SUMMARY OF BACKGROUND DATA: During a 7-month period, 61 patients (41 male patients, 20 female; average age, 40.3 years) with cervical spine trauma were studied. METHODS: All patients admitted to the authors' hospital with cervical spine injuries underwent magnetic resonance imaging and magnetic resonance angiography of their cervical spine. All magnetic resonance angiographies were examined for vertebral artery injury. Data on demographics and the injury were recorded. RESULTS: Complete disruption of blood flow through the vertebral artery was demonstrated by magnetic resonance angiography in 12 of the 61 patients (19.7%). Ten of the 12 patients (83%) had either flexion distraction or flexion compression injuries. Age, sex, mechanism of injury, neurologic impairment, and associated injuries were not statistically significant in predicting the presence of a vertebral vessel occlusion. CONCLUSION: The findings in this study may support the need for vertebral vessel evaluation in selective patients, particularly those with flexion injuries and with neurologic symptoms consistent with vertebral artery insufficiency syndrome that do not correlate with the presenting bone and soft-tissue injuries.     

Effect of subarachnoid bupivacaine block on anesthetic requirements for thiopental in rats

BACKGROUND: Subarachnoid bupivacaine blockade has been reported to reduce thiopental and midazolam hypnotic requirements in patients. The purpose of this study was to examine if local anesthetically induced lumbar intrathecal blockade would reduce thiopental requirements for blockade of motor responses to noxious and nonnoxious stimuli in rats. METHODS: After intrathecal and external jugular catheter placement, rats were assigned randomly to two groups in a crossover design study, with each rat to receive either 10 microl of 0.75% bupivacaine or 10 microl of normal saline intrathecally. The doses of intravenously administered thiopental required to ablate the eyelid reflex, to block the withdrawal reflex of a front limb digit, and to block the corneal reflex were compared. In two separate groups of animals, hemodynamic parameters and concentrations of thiopental in the brain were compared between intrathecally administered bupivacaine and saline. RESULTS: The thiopental dose required to block the described responses was decreased with intrathecally administered bupivacaine versus intrathecally administered saline from (mean +/- SD) 40 +/- 5 to 24 +/- 4 mg/kg (P < 0.001) for the eyelid reflex, from 51 +/- 6 to 29 +/- 6 mg/kg (P < 0.005) for front limb withdrawal, and from 67 +/- 8 to 46 +/- 8 mg/kg (P < 0.01) for the corneal reflex. The concentration of thiopental in the brain at the time of corneal reflex blockade for the group given bupivacaine was significantly lower than in the group given saline (24.1 vs. 35.8 microg/g, P = 0.02). CONCLUSION: This study demonstrates that lumbar intrathecally administered local anesthetic blockade decreases anesthetic requirements for thiopental for a spectrum of end points tested. This effect is due neither to altered pharmacokinetics nor to a direct action of the local anesthetic on the brain; rather, it is most likely due to decreased afferent input.     

Effects of thiopental and sevoflurane on hemodynamics during anesthetic management of electroconvulsive therapy

The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.     

Stability of thiopental sodium and propofol in polypropylene syringes at 23 and 4 degrees C

The stability of thiopental sodium and propofol in an admixture stored in polypropylene syringes at room temperature and under refrigeration was studied. Propofol injection 10 mg/ mL and thiopental sodium 25 mg/mL were mixed to final concentrations of 5 and 12.5 mg/mL, respectively. The admixture was put into 60-mL polypropylene syringes, and two syringes were stored at 23 degrees C and two at 4 degrees C. For solutions stored at 23 degrees C, samples were taken at 0, 4, 8, 24, 48, 72, 120, 168, 216, 240, and 264 hours, and for samples stored at 4 degrees C, samples were taken at 0, 4, 8, 24, 48, 72, 120, 168, 216, and 312 hours. Drug concentrations were determined by high-performance liquid chromatography. Thiopental sodium and propofol retained > 90% of their initial concentrations for up to 312 hours at 4 degrees C. At 23 degrees C, > 90% of the initial concentration was retained by propofol for up to 120 hours and by thiopental sodium for up to 240 hours. No visual changes or significant change in pH occurred in any sample. When mixed and stored in polypropylene syringes, propofol 5 mg/mL and thiopental sodium 12.5 mg/mL were stable for up to 312 hours at 4 degrees C and for up to 120 hours at 23 degrees C.     

Effects of etomidate, propofol and thiopental anaesthesia on arteriolar tone in the rat diaphragm

We have assessed, by intravital microscopy in rats, the effects of different anaesthetics on diaphragmatic arteriolar diameter. Rats were anaesthetized with etomidate, propofol or thiopental (groups E, P and T, respectively) and the diameters of the arterioles were measured sequentially at baseline and after topical application of either mefenamic acid (MA, 20 mumol litre-1) or N omega-nitro-L-arginine (NNA, 300 mumol litre-1), inhibitors of prostaglandins and nitric oxide, respectively. In group E, baseline arteriolar diameters were significantly higher than those in the two other groups (P < 0.01). MA and NNA induced significant constriction in the three groups (P < 0.001). However, whereas constriction induced by NNA was similar in the three groups, constriction induced by MA was significantly higher in group E compared with groups P and T (P < 0.05). We conclude that diaphragmatic arteriolar diameters in rats were greater during etomidate than during thiopental or propofol anaesthesia. This phenomenon may be mediated by prostaglandins.     

Reinduction of the hypnotic effects of thiopental with NSAIDs by decreasing thiopental plasma protein binding in humans

The angioscopic evaluation of the carotid bifurcation has proved valuable for intraoperative quality control after carotid endarterectomy (CEA). From January 1989 to July 1990, intraoperative angioscopy was performed in 196 patients undergoing CEA. We used a 2.2, 2.8 or 3.6 mm angioscope inserted at the end of the CEA through the remaining opening in the suture line. The angioscopic findings were classified as follows: I--no pathology (68%), II--thrombi, smaller debris, suture irregularities (29%), III--intima flap, endoscopic removal (3%), IV--intima flap, surgical redo (3%). Our results support the practicability and importance of intraoperative angioscopy for surgical decision making. It is possible to rinse out thrombi or remove remaining debris using flexible forcepy, under direct visual control. There were no significant complications related to the angioscopic procedure.     

Cardiorespiratory effects of combined midazolam and butorphanol in isoflurane-anesthetized cats

A case is reported of a child born with a developmental field defect of the first branchial arch in whom there was partial obstruction of the oropharynx by a horseshoe-shaped mass of what was thought to be tonsillar tissue. 'Tonsillectomy' was performed but histopathological examination of the excised specimens showed them to be almost entirely made up of salivary gland tissue.     

Cardiorespiratory effects of breathing and relaxation instruction in myocardial infarction patients

The effect of individual instruction in relaxation and breathing, additional to an exercise training program, was investigated in 76 post-myocardial infarction patients after rehabilitation and at 3 months follow-up. Respiration rate (RR), heart rate (HR) and respiratory sinus arrhythmia (RSA) were the outcome variables used to compare experimental (exercise plus relaxation) and control (exercise without relaxation) groups. HR and RR decreased slightly during 20-min sessions of supine measurement. This response did not vary between sessions (pre-rehabilitation, post-rehabilitation and after 3-month follow-up). RSA tended to decrease during the sessions. The within-session reduction in RSA became more apparent in the control group after treatment and less so in the experimental group. RR decreased in the experimental group after rehabilitation, but not in the control group. HR decreased for all patients, but the decrease was larger in the experimental group. This effect was associated with the lower RR. RSA did not change in the control group but increased in the experimental group, during both normal and deep breathing. This effect was also associated with a slower RR and became marginally significant when RR was statistically controlled for. We conclude that the relaxation intervention induced a slower breathing pattern which was associated with beneficial effects on resting HR and RSA. Further study is warranted to clarify the degree to which reduced respiration rate is an indicator of lower sympathetic arousal or merely a concomitant of the learned breathing technique.     

Selective toxicity of the general anesthetic propofol for GABAergic neurons in rat brain cell cultures

The intravenous, short-acting general anesthetic propofol was applied to three-dimensional (aggregating) cell cultures of fetal rat telencephalon. Both the clinically used formulation (Disoprivan, ICI Pharmaceuticals, Cheshire, England) and the pure form (2,6-diisopropylphenol) were tested at two different periods of brain development: immature brain cell cultures prior to synaptogenesis and at the time of intense synapses and myelin formation. At both time periods and for clinically relevant concentrations and time of exposure (i.e., concentrations > or = 2.0 micrograms/ml for 8 hr), propofol caused a significant decrease of glutamic acid decarboxylase activity. This effect persisted after removal of the drug, suggesting irreversible structural changes in GABAergic neurons. The gamma-aminobutyric acid type A (GABAA) blocking agents bicuculline and picrotoxin partially attenuated the neurotoxic effect of propofol in cultures treated at the more mature phase of development. This protective effect was not observed in the immature brain cells. The present data suggest that propofol may cause irreversible lesions to GABAergic neurons when given at a critical phase of brain development. In contrast, glial cells and myelin appeared resistant even to high doses of propofol.     

Clinical efficacy and safety of propofol or ketamine anaesthesia in dogs premedicated with medetomidine

Combinations of medetomidine with either propofol or ketamine were compared for the sedation and induction of anaesthesia in dogs undergoing a variety of surgical (60 per cent) and non-surgical (40 per cent) procedures. Eighty-four dogs were used at four sites. Medetomidine was administered intramuscularly at a dose of 1000 micrograms/m2 body surface area 10 to 15 minutes before the induction of anaesthesia by the administration of propofol (n = 44) or ketamine (n = 40) dosed to effect. The dogs became sedated by medetomidine after a mean (sd) time of 6.7 (5.4) minutes, and their heart rates and respiration rates decreased. Sixteen of the dogs suffered an adverse effect, 13 of them vomited. Anaesthesia was induced by the intravenous administration of propofol (2.1 [0.7] mg/kg) or ketamine (3.7 [1.9] mg/kg), and further doses of the anaesthetic were given, depending on the length of the operation, once in 17 per cent, twice in 11 per cent and three or more times in 24 per cent of the cases. The heart rate of the dogs anaesthetised with ketamine was significantly higher than that of the dogs anaesthetised with propofol, but there were no other significant physiological differences. There were 11 adverse side-effects in the ketamine group compared with five in the propofol group and they were generally more severe. The quality of the recovery from anaesthesia was considered to be smooth in 89 per cent of the propofol group but in only 63 per cent of the ketamine group.     

Placental transfer and neonatal effects of propofol in caesarean section

Rheumatoid arthritis (RA) patients are at higher risks of bacterial infection than healthy subjects. Polymorphonuclear leukocytes (PMN) are the first line of nonspecific cellular defence against these infections. We tested the hypothesis that abnormal directed migration of PMN may be one reason for the increased infection rate of RA patients. PMN migration was investigated in 68 peripheral blood samples of 15 RA patients compared with 64 samples of healthy controls in a novel whole blood in vitro membrane filter assay. The migration of PMNs from RA patients and controls was stimulated using the bacterial chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP). Unstimulated PMN migration of RA patients was increased compared with healthy controls as measured by the following parameters: (a) absolute number of migrant PMNs (1954+/-87 vs. 1238 +/-58 PMN/mm2), (b) percentage of PMNs migrated into the filter (total migration index, TMI) (28.6+/-0.9 vs. 24.0+/-0.8%), (c) the distance half the migrating PMNs had covered (distribution characteristic, DC) (22.6+/-1.1 vs. 16.1+/-0.6 mm) and (d) the product of TMI and DC (neutrophil migratory activity, NMA) (669.0+/-45.0 vs. 389.0+/-18.9). fMLP stimulated PMNs of RA patients showed defective migration compared to unstimulated samples as shown by (a) a reduced number of migrant PMNs (1799+/-93 PMN/mm2), (b) lower TMI (26.1+/-0.9%), (c) unremarkable altered distribution characteristic (22.9+/-0.8 mm) and (d) significant reduced migratory activity (600.0+/-30.0). Our data suggest that the high incidence of infections in RA patients may partly be caused by defective migratory activity of PMNs to bacterial chemoattractants as demonstrated by fMLP.     

Effect of propofol as an agent for anesthetic induction on pituitary-adrenocortical function during anesthesia and surgery

Effect of propofol as an agent for anesthetic induction on plasma levels of cortisol, beta-endorphin-like immunoreactivity (beta-ELI), growth hormone (GH) and prolactin were evaluated in 20 non-abdominal surgical patients ranged in ages from 19 to 64 years. Anesthesia was induced with either intravenous propofol 2-2.5 mg in ten patients or intravenous thiopental 4-5 mg in the remaining 10 patients as the control group, and succinylcholine was administered intravenously to facilitate tracheal intubation. Enflurane-nitrous oxide-oxygen was then given to maintain anesthesia in all the patients of both groups. Plasma cortisol levels decreased slightly with anesthesia in the propofol group, but they increased slightly after anesthetic induction in the control group. Therefore they were significantly lower in the propofol group than those in the control group. They tended to increase gradually during surgery and reached the peak value after the emergence from anesthesia in both groups. Plasma beta-ELI levels were unchanged with anesthesia alone in the patients of both groups. They tended to increase gradually during surgery and reached the peak value after the emergence from anesthesia in both groups. Plasma GH levels were not affected with anesthesia, but they increased slightly during surgery in both groups. Plasma prolactin levels increased significantly during anesthesia and surgery in both groups, and they decreased after the emergence from anesthesia but were still significantly higher than the preanesthetic values in both groups. The authors' findings suggest that effects of propofol as an agent for anesthetic induction on pituitary-adrenocortical function during anesthesia and surgery are comparable to those of thiopental, and that propofol does not exert inhibitory effect on pituitary-adrenocortical function during anesthesia and surgery.     

Pharmacodynamics and pharmacokinetics of thiopental

Thiopental is an ultra short-acting barbiturate which remains the standard against which other induction agents are judged; it is also indicated for the therapy of brain hypoxic-ischaemia injuries and status epilepticus. Aspects of drug distribution that govern the onset and end of drug effect have been intensively studied to determine which parameters (in patient characteristics, diseases and administration modalities) influence effective dose and concentrations in individual patients. Thiopental has been used as a reference for pharmacokinetic and/or pharmacodynamic models in the study of rapid and short acting effect drugs. In anaesthesiology the pharmacokinetics of thiopental are described as linear; when doses and duration of treatment increase, nonlinear pharmacokinetics occur because of the saturation and/or the induction of the metabolism.     

Antioxidant effects of propofol in human hepatic microsomes: concentration effects and clinical relevance

Parvoviruses of rodents are endowed with oncosuppressive properties. In particular, parvoviral infections protect host animals from spontaneous and chemical- or virus-induced tumour initiation in laboratory animals. The present study was undertaken to substantiate the capacity of parvovirus H-1 to inhibit therapeutically the growth of established tumours originating from human carcinoma cells implanted in recipient mice. To this end, quickly growing s.c. carcinomas were established by injection of human cervical carcinoma cells (HeLa) into immunodeficient (SCID) mice. Tumour-bearing mice subsequently were inoculated with H-1 at various multiplicities of infection. H-1 virus infection led to regression of tumours, the onset and efficiency of which were dose-dependent.     

Binding of thiopental to plasma proteins: effects on distribution in the brain and heart

Thiopental-14C (30 mg and 10 muCi/kg) was injected intravenously into rats 36-48 hours following bilateral nephrectomy and one minute after pretreatment with sulfadimethoxine (30 mg/kg, iv). Control groups of normal and sham-operated animals were used. The distributions of radioactivity in plasma, brain, and heart 1, 5, and 30 minutes after injection were examined. Uremic and sulfonamide-pretreated rats showed significantly higher levels of 14C in brain and heart and more free thiopental in plasma at each time than did control animals. There was a significant correlation between the free thiopental in plasma and total drug concentrations in the brain and heart. Uremic rats bound less thiopental in plasma compared with controls in spite of normal total plasma protein and albumin concentrations. It is concluded that reduced protein binding of thiopental leads to accelerated distribution and increased drug concentrations in the brain and and heart.     

Sevoflurane (SEVOrane) as an inhalation anesthetic in dogs in comparison with halothane and isoflurane

1969 Sevofluran was synthesized and in December 1995 licensed for clinical use in Germany. The low blood/gas partition coefficient is responsible for the fast uptake and elimination of sevoflurane. Sevoflurane does not irritate the airway. In human medicine no side effect of liver- and kidney function have been seen after sevofluran anaesthesia. There is low cardiovascular and respiratory depression caused by sevoflurane. In this study the use of sevoflurane in dogs should be tested and compared with isoflurane and halothane anaesthesia. All dogs were premedicated with /-methadon and diazepam. No significant depression of the cardiovascular system was seen. Neither kidney-nor hepatotoxic side effects could be found after sevoflurane, isoflurane and halothane anaesthesia. After sevoflurane anaesthesia the dogs woke up quietly and without any excitation and were able to stand on average ten minutes earlier after sevoflurane anaesthesia than after isoflurane and 85 minutes earlier than after halothane anaesthesia.     

Detection and effects of helicobacters in healthy dogs and dogs with signs of gastritis

OBJECTIVES: To determine prevalence, colonization density, and distribution of helicobacters and gastric histologic findings in healthy dogs and dogs with signs of gastritis; to evaluate association of colonization density and gastric inflammation; and to compare the number of Helicobacter spp with degree of inflammation. DESIGN: Cross-sectional prevalence survey. ANIMALS: 25 healthy dogs and 21 dogs with signs of gastritis. PROCEDURE: During endoscopy, gastric mucosal biopsy specimens were obtained from healthy and affected client-owned dogs. Histologic and cytologic evaluation and results of a urease test were used for detecting helicobacters, which were identified definitively by use of transmission electron microscopy and bacterial culture. RESULTS: Helicobacters were detected in all 25 healthy and 20 of 21 affected dogs. Cytologic examination was a more sensitive method than histologic examination or the urease test. Helicobacters were found least frequently and in fewest number in the antrum in both groups of dogs. Gastric inflammation was evident in both groups of dogs and did not differ significantly between groups. A significant association was not detected between colonization density or the number of Helicobacter spp and degree of gastric inflammation. In both groups, H bizzozeronii, H felis, and H salomonis were cultured. CLINICAL IMPLICATIONS: Histologically verified chronic gastritis is common in dogs with signs of gastritis as well as in healthy dogs. Colonization density of helicobacters was not associated with degree of gastric inflammation in the dogs of our study. It remains to be determined whether certain strains of Helicobacter spp can induce gastritis in dogs.