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Biomedical subjects

B Bissonnette

Publications and source records attributed to B Bissonnette.

At least 91 records · Page 5Linked to original sources
PubMed1991

Transcranial Doppler: response of cerebral blood-flow velocity to carbon dioxide in anaesthetized children.

To determine the effect of carbon dioxide on the cerebral circulation in anaesthetized infants and children, 13 healthy children, ASA physical status I or II, between three months and seven years of age and scheduled for urologic surgery, were studied. Anaesthesia was induced with thiopentone and vecuronium. After tracheal intubation, anaesthesia was maintained with 70 per cent nitrous oxide in oxygen, fentanyl 2 micrograms.kg-1, vecuronium 0.05 mg.kg-1 and 0.8-1.0 per cent end-tidal isoflurane. A caudal block was performed before surgery. Systolic arterial pressure, heart rate, oxygen saturation, temperature, and end-tidal isoflurane were maintained constant. Ventilation was adjusted to achieve an end-tidal PCO2 (PETCO2) of 20 mmHg. The PETCO2 was then randomly adjusted between 20 and 80 mmHg by the addition of carbon dioxide from an exogenous source. Cerebral blood flow velocity increased logarithmically and directly with the PETCO2 (r2 = 0.56). There were no complications associated with the use of transcranial Doppler sonography. These data indicate that CO2 has a direct effect on the velocity of blood in the middle cerebral artery in infants and children anaesthetized with isoflurane.

Anesthesia, Inhalation↗
PubMed1991

Cerebrovascular responses to carbon dioxide in children anaesthetized with halothane and isoflurane.

To determine the effects of isoflurane and halothane on cerebrovascular reactivity to CO2, 30 children aged one to six years were anaesthetized with isoflurane or halothane in an air and oxygen mixture with an FIO2 of 0.3. The end-tidal concentrations (0.5 minimum alveolar concentration (MAC) or 1.0 MAC) of isoflurane or halothane were age-adjusted. After achieving a steady-state at both 0.5 MAC and 1.0 MAC isoflurane and halothane, the end-tidal carbon dioxide tension (PETCO2) was randomly adjusted to 20, 40, or 60 mmHg. Cerebral blood flow velocity (CBFV) and the cerebrovascular resistance index (RI+) in the middle cerebral artery (MCA) were measured by a transcranial Doppler monitor. Three measurements of CBFV and RI+ were obtained at each PETCO2 and isoflurane or halothane concentration. Any rise in the PETCO2 caused an increase in CBFV during both 0.5 MAC (r2 = 0.99 and 0.99) and 1.0 MAC (r2 = 0.96 and 0.95) isoflurane and halothane anaesthesia, respectively (P less than 0.05). The CBFV for isoflurane increased as PETCO2 increased from 20 to 60 mmHg for both 0.5 MAC and 1.0 MAC (P less than 0.05). The CBFV for halothane increased as PETCO2 increased from 20 to 40 mmHg for both 0.5 MAC and 1.0 MAC halothane (P less than 0.05), but did not change as PETCO2 increased from 40 to 60 mmHg for both 0.5 MAC and 1.0 MAC halothane. The RI+ showed an inverse relationship with CBFV at each PETCO2 for 0.5 MAC (r2 = 0.98 and 0.99) and 1.0 MAC (r2 = 0.76 and 0.53) isoflurane and halothane, respectively (P less than 0.05). The CBFV did not differ significantly between 0.5 and 1.0 MAC isoflurane and halothane at corresponding PETCO2 values. The cerebrovascular response to CO2 at 20 mmHg between 0.5 MAC and 1.0 MAC halothane was not significantly different. These data strongly suggest that isoflurane and halothane in doses up to 1.0 MAC do not affect the cerebrovascular reactivity of the MCA to CO2 in anaesthetized, healthy children.

Anesthesia, Inhalation↗
PubMed1991

Determination of bupivacaine in plasma by high-performance liquid chromatography. Levels after scalp infiltration in children.

The local anaesthetic bupivacaine could be very useful for analgesia in pediatric neurosurgery. Since systemic toxic reactions to bupivacaine are correlated with high plasma levels it was important, as an adjunct to clinical evaluation, to measure plasma bupivacaine. This report describes a high-performance liquid chromatography (HPLC) method for the quantitation of plasma bupivacaine. Sample preparation involves extraction into ether followed by back-extraction into HCl. After evaporation, the acid extract is redissolved and separated by reversed-phase chromatography. The assay is linear to 5 mg bupivacaine/L and shows excellent recovery and precision. With samples from children undergoing brain surgery following scalp infiltration with either 0.125% or 0.25% bupivacaine, plasma levels peak within 10 min, then fall rapidly to a plateau by 30 min. This plateau is maintained for at least 120 min. In no case did we find supposed toxic levels of bupivacaine.

Brain↗
PubMed1991

P6 acupuncture and postoperative vomiting after tonsillectomy in children.

We have studied the effect of P6 acupuncture on postoperative vomiting in 45 children undergoing tonsillectomy. After induction of anaesthesia and before the start of surgery, 50% of the patients received P6 acupuncture (in the middle of the ventral surface of the wrist) for 5 min. There was no difference in the incidence of vomiting between the acupuncture (39%) and non-acupuncture (36%) groups. We conclude that, when administered after induction of anaesthesia, P6 acupuncture is ineffective in reducing vomiting after tonsillectomy in children.

Acupuncture Points↗
PubMed1991

Pharmacodynamics of high-dose vecuronium in children during balanced anesthesia.

To compare the speed of onset, intubating conditions, duration of action, and recovery from neuromuscular blockade with vecuronium to those with succinylcholine, 40 ASA physical status 1 or 2 children (ages 2-9 yr) were studied during N2O-O2-opioid anesthesia. Each child was randomly assigned to receive a bolus dose of one of the following muscle relaxants: succinylcholine 2.0 mg/kg (n = 10), vecuronium 0.1 mg/kg (n = 10), vecuronium 0.2 mg/kg (n = 10), or vecuronium 0.4 mg/kg (n = 10). The evoked electromyogram of the abductor digiti minimi to train-of-four stimulation was monitored. We found that with succinylcholine, the time to 95% twitch depression (speed of onset, mean +/- SD), 24 +/- 7 s, was significantly less than that with each dose of vecuronium: 0.1 mg/kg, 83 +/- 21 s; 0.2 mg/kg, 58 +/- 17 s; and 0.4 mg/kg, 39 +/- 11 s, respectively (P less than 0.05). The time to laryngoscopy and intubation did not differ significantly between succinylcholine (48 +/- 10 s) and vecuronium 0.4 mg/kg (57 +/- 13 s); however, both were significantly less than than with vecuronium 0.1 and 0.2 mg/kg (P less than 0.005). The intubating conditions were excellent in 100% of patients. The duration of action was least with succinylcholine (5.7 +/- 1.5 min) and increased with increasing doses of vecuronium: 0.1 mg/kg, 23.9 +/- 5.1 min; 0.2 mg/kg, 55.2 +/- 11.6 min; and 0.4 mg/kg, 74.6 +/- 9.9 min, respectively (P less than 0.001). The recovery index was most rapid with succinylcholine (1.6 +/- 0.4 min) and was slowest with vecuronium 0.4 mg/kg (22.6 +/- 2.1 min) (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1991

Cerebral hemodynamics in neonates and infants undergoing cardiopulmonary bypass and profound hypothermic circulatory arrest: assessment by transcranial Doppler sonography.

Profound hypothermic circulatory arrest (PHCA) is followed by a transient period of increased intracranial pressure and a longer period of neurophysiologic dysfunction. To investigate the effect of cardiopulmonary bypass (CPB) with PHCA on cerebral hemodynamics, we used transcranial Doppler sonography to measure cerebral blood flow velocity in 10 neonates and infants before and after PHCA. Cerebral blood flow velocity was compared before and after PHCA during normothermic cardiopulmonary bypass at the same mean arterial pressure, central venous pressure, hematocrit, and arterial carbon dioxide tension. Cerebral blood flow velocity decreased exponentially with decreasing nasopharyngeal temperature before PHCA (P less than 0.05) and remained decreased after PHCA during normothermic CPB, compared with values for normothermic CPB before PHCA (P less than 0.005). During normothermic CPB after PHCA, the modified cerebral vascular resistance (mm Hg.cm.s-1) was increased above values for normothermic CPB before PHCA (P less than 0.05). The results of this study suggest that the observed increase in intracranial pressure during PHCA is not caused by increased cerebral perfusion, but rather that cerebral perfusion is reduced in response to a decreased demand for cerebral metabolic oxygen.

Cardiopulmonary Bypass↗
PubMed1991

Scalp infiltration with bupivacaine in pediatric brain surgery.

To evaluate whether local anesthetic scalp infiltration blunts hemodynamic responses to craniotomy in anesthetized children (age, 2-18 yr), two concentrations of bupivacaine (0.125% and 0.25%) with vasoconstrictor (epinephrine 1:400,000) were compared with control data when a solution of vasoconstrictor alone was injected. Arterial plasma levels of bupivacaine were measured by high-pressure liquid chromatography. Statistically significant increases in mean arterial pressure and heart rate above baseline measurements occurred in the control group during the period between scalp incision and dural reflection (P less than 0.05). Both concentrations of bupivacaine prevented these increases. Mean arterial pressure and heart rate during scalp incision and scalp reflection were significantly higher in the control group than in both bupivacaine groups (P less than 0.05). Peak bupivacaine plasma levels (mean +/- SD) occurred either 5 or 10 min after infiltration and were significantly higher in the 0.25% group (0.48 +/- 0.31 microgram/mL) than the 0.125% group (0.14 +/- 0.13 microgram/mL) (P less than 0.05). These results suggest that bupivacaine infiltration blocks the hemodynamic response to craniotomy. A concentration of 0.125% bupivacaine with 1:400,000 epinephrine is as effective as 0.25% bupivacaine with 1:400,000 epinephrine at reducing the hemodynamic response to craniotomy. Because the lower concentration of bupivacaine produces lower blood levels, we recommend 0.125% bupivacaine with 1:400,000 epinephrine as a useful, safe adjunct to general anesthesia in children undergoing craniotomy.

Adolescent↗
PubMed1990

Hyperkalaemia during massive blood transfusion in paediatric craniofacial surgery.

Children undergoing major craniofacial surgery (MCFS) often require transfusion in excess of one blood volume. Therefore they were the subject of a retrospective review which looked at the longitudinal trend of plasma potassium concentration [K+] during surgery. Ten of eleven children had a statistically significant increase in plasma potassium concentration during their intraoperative course and in five the potassium concentration exceeded 5.5 mmol.L-1. This was in contrast to the stable intraoperative plasma [K+] observed in a control group which did not receive blood transfusion. All MCFS children received a blood transfusion with red blood cell concentrates (RBCconc). The age of the units of RBCconc which had been transfused was 16.1 +/- 8.4 days. The amount of extracellular potassium in 28 units of RBCconc was determined in order to estimate the amount of free potassium (Kdose) which the MCFS group received. The plasma [K+] in units of RBCconc less than 1 week of age was less than 20 mmol.L-1, whereas in units aged greater than 2 weeks it was greater than 40 mmol.L-1. The estimated Kdose was 0.2-1.6 mmol.kg-1. We concluded that the amount of extracellular potassium in units of RBCconc was clinically important and may give rise to hyperkalaemia during massive blood transfusion.

Blood Transfusion↗
PubMed1990

[Lidocaine aerosol following tonsillectomy in children].

Post-tonsillectomy analgesia was compared using ten per cent aerosol lidocaine or 1.5 mg.kg-1 intramuscular codeine. Thirty ASA physical status I or II children between two and ten years of age were assigned, in a random fashion, to one of two groups: Group A received codeine 1.5 mg.kg-1 intramuscularly, Group B received a total dose of 4 mg.kg-1 of ten per cent aerosol lidocaine on the tonsillar beds. For both groups, the treatment was administered at the end of the surgical procedure. The postoperative comfort state was assessed on a global scale using the following statement: (1) comfortable = 1, (2) agitation = 2, (3) uncontrollable = 3. Assessment of postoperative comfort was recorded after 20 min in the post-anaesthetic recovery room. Blood samples for lidocaine concentration estimation were obtained at 5, 7.5, 10, and 15 min after administration. Finally, the time of recovery was recorded. The immediate post-anaesthetic comfort observed with ten per cent aerosol lidocaine was statistically superior to that obtained with 1.5 mg.kg-1 intramuscular codeine. The maximal systemic lidocaine concentration which was 2.1 +/- 0.2 micrograms.ml-1 was well below the accepted toxic level of 5.3 micrograms.ml-1. The recovery room times were not statistically different between the two groups. In conclusion, 4 mg.kg-1 of ten per cent aerosol lidocaine applied directly on the tonsillar beds was shown a superior immediate post-tonsillectomy analgesic technique.

Aerosols↗
PubMed1990

Hyperkalaemia during rapid blood transfusion and hypovolaemic cardiac arrest in children.

A morbidity and mortality review documented a high occurrence of hyperkalaemia in cardiac arrests associated with rapid blood transfusion, which resulted in further study. In order to stimulate events during rapid blood transfusion and cardiac arrest, the central circulation was modeled as a linear one compartment, and used to stimulate a child who suffered a hypovolaemic cardiac arrest and was resuscitated with rapid blood transfusion (RBT). The simulation suggested that the combination of RBT and a low cardiac output state could be associated with hyperkalaemia, if the potassium concentration in the plasma fraction of the transfused blood was greater than or equal to 10 mmol.L-1. In an associated clinical study the plasma potassium concentration during cardiac arrest was documented from a retrospective review of 138 cardiac arrests in a paediatric population. Patients were divided into two groups. The RBT-group received a rapid blood transfusion during resuscitation. The non-RBT group did not receive blood during resuscitation. During cardiac arrest the plasma [K] in the non-RBT group was 5.63 +/- 2.39 mmol.L-1 compared with 8.23 +/- 1.99 mmol.L-1 in the RBT-group (P less than 0.05). The hyperkalaemia during cardiac arrest in the RBT-group could be explained as a consequence of RBT to a hypovolaemic child with a low cardiac output.

Adolescent↗
PubMed1990

Flare reaction following caudal analgesia.

The following case reports describe obvious and marked vascular changes over the S3 dermatome in two children following the administration of bupivacaine 0.125 per cent via the caudal route. These flare reactions were typical of an axon reflex. Vasodilatation in these two case reports could have been mediated by direct stimulation of the S3 routes by the local anaesthetic solution.

Analgesia, Epidural↗
PubMed1990

The thermoregulatory threshold in infants and children anesthetized with isoflurane and caudal bupivacaine.

Hypothermia in anesthetized adults provokes centrally mediated, peripheral thermoregulatory vasoconstriction at threshold temperatures approximately 2.5 degrees C below normal. The weight dependence of thermoregulatory vasoconstriction was evaluated in 33 unpremedicated pediatric patients receiving isoflurane/oxygen anesthesia (end-tidal concentrations approximately 0.9%) and caudal anesthesia with bupivacaine. The patients were prospectively assigned to four weight groups (5-10 kg, 10-20 kg, 20-30 kg, and 30-50 kg). Central temperature was measured at the tympanic membrane, and average skin surface temperature was determined from four cutaneous sites; mean body temperature was calculated from central and average skin temperatures. Finger blood flow was determined using laser Doppler flowmetry and forearm-fingertip skin temperature gradients. Significant peripheral vasoconstriction was prospectively defined as a laser Doppler flow index 50% of the value recorded 10 min after induction of anesthesia. Thermoregulatory thresholds were defined as the tympanic membrane or mean body temperatures at which significant vasoconstriction occurred. Vasoconstriction occurred in 32 of the patients at temperatures ranging from 34.4 to 35.3 degrees C. Central and mean body threshold temperatures did not differ among the groups, and were similar to those observed previously in adults. There was a good correlation between laser Doppler flowmetry and forearm-fingertip skin temperature gradients in individual patients.

Anesthesia, Caudal↗