PubMed Health⌕ Search

Biomedical subjects

J E Heavner

Publications and source records attributed to J E Heavner.

At least 55 records · Page 3Linked to original sources
PubMed1988

The cardiovascular effects of anticholinergic agents administered during halothane anaesthesia in children.

The cardiovascular effects of anticholinergic agents administered during halothane anaesthesia were studied in 31 children aged 1-12 years undergoing peripheral orthopaedic surgery. Either normal saline, glycopyrrolate (10 micrograms.kg-1) or atropine (20 micrograms.kg-1) was administered in randomized double-blind fashion during the induction of anaesthesia with halothane while the electrocardiogram was continuously recorded. After induction, the children were paralyzed with atracurium, intubated, and ventilated. Anaesthesia was maintained with N2O/O2 and halothane (up to 2.5% inspired). The concentrations of expired CO2 and halothane were measured continuously using mass spectrometry. Sixty-one percent (19/31) of the children developed one or more dysrhythmias. Junctional rhythm occurred in 74% (14/19) of the children with dysrhythmias, developed early during induction (mean +/- s.d. time = 2.29 +/- 2.0 min after commencement of induction), and usually resolved before the administration of the study drug (8/14). All dysrhythmias initially occurred before or during induction and none developed during intubation, during incision, during the maintenance of anaesthesia, or after the administration of anticholinergic agents. The data suggest that: 1) a combination of factors present during halothane induction is highly dysrhythmogenic especially for junctional rhythm; 2) junctional rhythm will resolve spontaneously; 3) the administration of an anticholinergic agent during halothane induction is safe but may be unnecessary in children greater than 1 year of age; and 4) the dysrhythmogenic factors present during induction are attenuated during the maintenance of halothane anaesthesia.

Anesthesia, Inhalation↗
PubMed1988

A simple and rapid high-pressure liquid chromatographic assay for pentobarbital and other barbiturates in serum.

A single extraction technique for measuring pentobarbital and other barbiturates in serum involved high-pressure liquid chromatography and UV detection yielding a sensitivity for pentobarbital of about 1 microgram/ml. We concluded that the assay provides a practical method for use in pharmacokinetic studies and in serum concentration monitoring in experimental animals.

Animals↗
PubMed1987

Respiratory and cardiovascular effects of halothane, isoflurane and enflurane delivered via a Jackson-Rees breathing system in temperature controlled and uncontrolled rats.

We studied the respiratory and cardiovascular effects of 1.25 MAC halothane, isoflurane and enflurane in oxygen delivered via the Jackson-Rees breathing system in 10 rats. Mean arterial pressure, heart rate and respiratory rate were depressed significantly (P less than 0.05) in rats (n = 5) whose body temperature was not controlled after 2 hr of anesthesia regardless of the inhalational agent. Respiratory and metabolic acidosis developed. The respiratory and cardiovascular depression was most marked under enflurane anesthesia. In normothermic rats (n = 5) the initial cardiovascular depression stabilized after 30 min of halothane and isoflurane anesthesia. Moderate respiratory depression developed (PCO2 48.42 +/- 2.48 torr with halothane vs. 41.02 +/- 1.68 torr with isoflurane). Because the cardiovascular and respiratory changes caused by halothane and isoflurane were far less than changes produced by enflurane, halothane or isoflurane is preferable to enflurane for maintaining anesthesia in rats. Maintenance of constant temperature minimizes the cardiovascular and respiratory disturbances.

Anesthesia, Inhalation↗
PubMed1986

Trichlorfon-induced congenital cerebellar hypoplasia in neonatal pigs.

The neuroteratogenicity of trichlorfon was evaluated in 3 groups of pregnant sows (8/group). The treatments were: control (no trichlorfon), trichlorfon (60 mg/kg of body weight) in the feed only on day 55 of gestation, or trichlorfon (60 mg/kg of body weight) in the feed on day 55 and day 70 of gestation. One week after farrowing, all newborn pigs were removed from the sows and were euthanatized. Brain and cerebellum weights of the newborn pigs were recorded. Mean cerebellum weights and cerebellum/total brain weight ratios of the neonatal pigs were 3.780 and 0.106 (group 1, n = 26), 3.183 and 0.098 (group 2, n = 42), and 2.986 and 0.088 (group 3, n = 61). Although trichlorfon interfered with cerebellar development and the severity of the trichlorfon-induced cerebellar hypoplasia was dosage-related, ataxia did not develop in the neonatal pigs.

Animals↗
PubMed1986

Legal implications of the extra-label use of drugs in food animals.

Although the Food and Drug Administration has never sanctioned the extra-label use of drugs in animals, it has not, until recently, objected when veterinarians deviated from label instructions as long as such use did not result in violative residues in food products derived from treated animals. However, because of the potential human health hazards associated with abuse of this position, the FDA has developed a less lenient policy toward the extra-label use of drugs in food animals. A brief review of the legislated responsibility and authority of the FDA with particular reference to the extra-label use of drugs in food animals is provided. Emphasis is placed on how anesthetics and anesthesia adjuncts in food animals can pose human health hazards.

Adjuvants, Anesthesia↗
PubMed1986

Lactate dehydrogenase isoenzymes in blood and cerebrospinal fluid from healthy beagles.

Serum and CSF lactate dehydrogenase (LDH) activity and LDH isoenzyme profile, as well as total protein, were measured in samples obtained from 26 healthy Beagles. The LDH activity in serum was approximately 10 times that in the CSF. The CSF LDH isoenzyme profile was a mirror image of the serum LDH isoenzyme profile. Age was negatively correlated (ie, as age increased, the activity decreased) with LDH3 in CSF and LDH5 in serum and was positively correlated with LDH1 in serum. Seemingly, simultaneous measurement of serum and CSF LDH activity and LDH isoenzyme profile can aid in establishing status of the blood-brain barrier, whether brain damage exists and whether other organ systems are involved.

Aging↗
PubMed1986

Cardiac dysrhythmias induced by infusion of local anesthetics into the lateral cerebral ventricle of cats.

The hypothesis that neurogenically mediated cardiac arrhythmias can be induced by the intracerebroventrical (ICV) infusion of local anesthetic solutions was tested in 11 chronically prepared, unmedicated cats. Test substances were bupivacaine (0.1%), lidocaine (0.4%), procaine (0.4 or 0.8%), or saline (pH 5.8). Cats received one or more of the test substances with two or more days between infusions. Four cats were also given bupivacaine intravenously at 1.1 and 1.4 mg/kg to help determine whether ECG changes after ICV injection of local anesthetic were due to direct cardiac action after systemic absorption. Total dose was 3.8-7.8 X the largest ICV dose (0.7 mg). No ventricular arrhythmias were observed after the ICV infusion of saline or with intravenous doses of bupivacaine as large as 1.4 mg/kg. Only one of six cats given lidocaine ICV developed sustained, severe ventricular arrhythmias. Five of seven cats given ICV procaine developed ventricular arrhythmias. All ten cats given ICV bupivacaine developed ventricular arrhythmias. It is concluded that local anesthetics can produce neurogenically mediated ventricular arrhythmias in cats and that, of the three local anesthetics tested, bupivacaine is the most potent and effective and lidocaine is the least potent and effective.

Anesthetics, Local↗
PubMed1985

In vitro study of the effect of epidural blood patch on leakage through a dural puncture.

Pressure resistance of an experimental epidural blood patch was studied in vitro. Pieces of canine lumbar dura were perforated with a 19-gauge needle (n = 12) or a 25-gauge needle (n = 6) and kept between the intercommunicating chambers of a plexiglass apparatus. One chamber (epidural side) was filled with autologous blood and the other chamber (subdural side) was filled with autologous cerebrospinal fluid. Control studies consisted of dural specimens not exposed to blood on the epidural side (19-gauge, n = 8; 25-gauge, n = 4). After 30 min, the dura was removed and placed in saline for inspection. In blood-treated specimens small sheets of coagulated blood were found attached to the epidural side of the dura, and in eight of the twelve of 19-gauge puncture experiments and one of the six of the 25-gauge puncture experiments clotted blood was visible on the subdural side. The dura was then placed back into the chamber for pressure testing 30 min or 16-18 hr later. The subdural chamber was filled with saline and air was left in the epidural chamber. Pressure (1.5, 20, 30, 40, and 50 mm Hg) was applied by injecting additional saline into the subdural chamber. Each pressure level was maintained for 5 min. Saline leaked through the perforation in all control specimens at 1.5 mm Hg pressure. Four blood-treated specimens showed some leakage at 20 mm Hg. All dura specimens perforated with a 19-gauge needle leaked at 40 mm Hg, five of them only at the lowest score rate, 1-4 drops/5 min. One blood-patched dura perforated with a 25-gauge needle did not leak until the pressure reached 50 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Permeability of the blood-milk barrier to methylene blue in cows and goats.

A 2% aqueous solution of methylene blue was administered as a single intravenous (i.v.) bolus injection (10 mg/kg) to six lactating cows and seven lactating goats and a continuous i.v. drip to five lactating goats. The same dose was administered as a 10% solution by intramammary infusion to five lactating goats. Blood and milk samples collected at various times after these treatments were assayed for the drug by a colorimetric method. Methylene blue, a highly charged molecule (pKa less than or equal to 1), passed readily from blood into milk; drug concentrations in milk 4-36 h after the single i.v. bolus injection were higher than those in blood. When examined at constant methylene blue levels in blood, a milk--blood ratio of 5:1 was observed. After intramammary infusion, the drug passed quickly into systemic circulation, peaked at 3 h and was still detectable in blood 12 h after infusion. The drug appeared in the urine within 15 min after intramammary infusion. The rapid movement of the drug across the blood--milk barrier cannot be explained on the basis of its known physicochemical properties or according to the pH--pKa passive diffusion concept.

Animals↗
PubMed1984

Depletion of antibiotics from the mammary gland of goats.

Four intramammary infusion products were tested in 10 normal goats to determine their rates of depletion from milk. The products tested, which are marketed for treatment of mastitis in the bovine, contained the single active ingredient erythromycin, oxytetracycline, penicillin, or cephapirin. Each mammary gland was infused, after the goats were milked, with the maximum recommended dose of test product (dosing frequency and quantity) for administration to lactating dairy cattle. With one exception, no antibiotics could be detected in the milk by the end of the bovine milk-discard period. Penicillin was detectable in the milk of one goat for 72 h after the last dose of product containing this antibiotic was given (60-h withdrawal period). Only the product containing oxytetracycline produced significant adverse reactions in the mammary gland. The applicator tips of the products were too large for atraumatic insertion into the teat opening of some goats. Overall, results of this limited study indicated that some intramammary infusion products can be used to treat mastitis in the goat if instructions for use in the bovine are followed.

Animals↗
PubMed1983

Profound arterial hypotension in dogs: brain electrical activity and organ integrity.

To determine whether non-invasive measurement of brain electrical activity can predict ischemic brain damage, we recorded the electroencephalogram (EEG) and somatosensory- (SEP) and auditory- (AEP) evoked potentials before, during, and after trimethaphan-induced profound arterial hypotension in dogs. The authors set out to compare the change in electrical activity with the degree of brain damage, as determined by microscopic examination. Dogs were anesthetized with halothane (1.4 vol % inspired), maintained horizontal (head at the level of the heart), and ventilated mechanically (FIO2 0.50); deviations from normal acid-base status were corrected. Twenty animals received a 1.5-mg/kg intravenous bolus of trimethaphan. Three animals were resistant to the drug. The remaining animals had profound hypotension [mean arterial blood pressure (MABP) at some steady level between 12 and 25 mmHg] for 1 h. Eight of these animals died during or soon after the hypotensive period as a consequence of cardiac arrest (three), intestinal bleeding (three) or unknown causes (two). In all survivors, EEG intensity and the amplitude of the SEP decreased during hypotension; both variables recovered with restoration of MABP. All nine animals surviving hypotension had no apparent neurologic or behavioral deficit nor any histologic evidence of ischemic brain cell injury. We were thus unable to find a MABP threshold for brain with minimal brain injury. Our findings suggest, under the conditions of our experiments, a great margin of tolerance for profound hypotension by the brain in this species. Other organ systems--the heart, gastrointestinal tract, and liver--proved to be more susceptible to ischemic damage. Eight of the nine surviving animals had elevations in serum alanine transaminase (SGPT), aspartate transaminase (SGOT), and alkaline phosphatase. Animals with the greatest increases in these enzymes showed centrilobular hepatocyte degeneration.

Animals↗
PubMed1983

Haloxon-induced delayed neurotoxicity: effect of plasma A (aryl) esterase activity on severity of lesions in sheep.

A markedly different response to the delayed neurotoxic effects of a single dose of 400 or 800 mg/kg of the organophosphorus anthelmintic haloxon was observed in two populations of sheep. Animals with a gentically determined low level of activity of the plasma enzyme A (aryl) esterase developed clinical signs of delayed neurotoxicity within one month. Lesions relating to degeneration of myelinated nerve fibers were seen in brain stem, spinal cord, and on occasion peripheral nerve. The incidence of clinical signs, and severity of lesions as determined by semiquantitative morphological study of the spinal cord, were greater in animals given the higher dose. Neither clinical signs nor lesions relating to organophosphate-induced delayed neurotoxicity were seen in sheep with high plasma activity of A esterase.

Animals↗