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Biomedical subjects

B Bissonnette

Publications and source records attributed to B Bissonnette.

At least 73 records · Page 4Linked to original sources
PubMed1992

Systolic arterial pressure determination by a new pulse monitor technique.

The Doppler ultrasound (DUS) technique is a widely accepted non-invasive technique to estimate systolic blood pressure (SBP) accurately in paediatric patients. The DUS has a number of limitations. A new pulse monitor, Mr Pulse (MP), operating on the principle of a finger plethysmograph, was developed to offer an alternative technique to estimate SBP. From 104 paired SBP measurements taken in 16 paediatric patients undergoing general anaesthesia, SBP determined by the MP technique correlated closely with that by the standard DUS technique (r2 = 0.98). Analysis of degree of agreement performed indicated that there was good agreement between SBP obtained by the MP and the DUS techniques. The mean +/- standard deviation of differences in paired SBP values between the two measurement techniques was 0.55 +/- 3.59 mmHg. Mr Pulse is as accurate as the DUS technique in estimating SBP and has the advantage of less critical sensor positioning as it is not subject to electrical interference. It has no electrical hazard.

Adolescent↗
PubMed1992

Ineffectiveness of acupuncture and droperidol in preventing vomiting following strabismus repair in children.

The antiemetic effects and side-effects of P6 acupuncture and droperidol pre-treatment were evaluated in a randomized, patient- and observer-blinded study. Ninety unpremedicated children of ASA physical status I or II undergoing outpatient strabismus repair, and aged over one year, were studied. All patients received intravenous thiopentone 5 mg.kg-1, atropine 0.02 mg.kg-1 and succinylcholine 1.5 mg.kg-1, and the trachea was intubated. Patients then received either intravenous droperidol 0.075 mg.kg-1, droperidol plus five minutes' P6 acupuncture, or acupuncture alone. Anaesthesia was maintained with nitrous oxide 66% and halothane 1.5-2.0% in oxygen with spontaneous ventilation. There was no difference in the incidence of vomiting in the droperidol group (17% before discharge from hospital and 41% up to 48 hours after discharge), combined treatment group (17% and 34% respectively) and acupuncture group (27% and 45% respectively). Corresponding figures for the incidence of vomiting before discharge were 17%, 17% and 27% respectively; these values were also not different. The incidence of restlessness was significantly greater in children receiving droperidol (63%) or both treatments (67%) than in those receiving acupuncture alone (30%; P = 0.007). P6 acupuncture and droperidol are equally ineffective in preventing vomiting within 48 hours of paediatric strabismus repair. Droperidol is associated with increased incidence of postoperative restlessness.

Acupuncture Therapy↗
PubMed1992

Chest wall motion during halothane anaesthesia in infants and young children.

Chest wall motion during anaesthesia may differ from the awake state because of the effect of anaesthetic agents on the muscles of respiration. The purpose of this study was twofold (1) to describe the pattern of chest wall motion in infants and children during halothane anaesthesia (HA) using respiratory inductive plethysmography (RIP) and (2) to calibrate the voltage output of RIP in units of volume. Seven infants (2.3 +/- 1.7 mo, 5.9 +/- 0.7 kg) and five children (2.9 +/- 1.1 yr, 15.5 +/- 1.5 kg) were studied. Since results in both age groups were qualitatively similar they are presented as a single group. Respiratory excursions of the rib cage (RC) and abdomen (ABD) were measured using RIP. Airflow was measured with a pneumotachograph. During spontaneous breathing the analogue signals of airflow, pressure, RC and ABD were recorded. Measurements were taken during (1) halothane anaesthesia and (2) during emergence from anaesthesia. The XY plots of the RC and ABD signals were plotted for each period. In addition the voltage output of the respiratory excursions of the RC and ABD signals was converted to units of volume using the simultaneous solution of equation method. The accuracy of conversion factors was validated by regression analysis of the predicted and measured tidal volume using breaths sampled at random throughout the entire period of study. Regression analysis of this relationship gave a slope between 0.85 and 1.15 (r2 value greater than 0.7) in five of the twelve patients. The pattern of chest wall motion in the XY plots showed synchronous motion between RC and ABD signals during HA in nine of the twelve patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia Recovery Period↗
PubMed1992

Thermoregulatory thresholds for vasoconstriction in pediatric patients anesthetized with halothane or halothane and caudal bupivacaine.

The thermoregulatory threshold for vasoconstriction has been studied in infants and children given isoflurane, but not in those given halothane anesthesia. More importantly, the effect of vasoconstriction on central temperature in pediatric patients remains unknown. Also unknown is the effect of caudal analgesia on vasoconstriction thresholds. Accordingly, in the first portion of this study, we determined the central thermoregulatory threshold in 23 infants and children given approximately 0.6% halothane and caudal anesthesia for abdominal surgery. Patients were prospectively assigned to one of four weight groups: 5-10, 10-20, 20-30, and 30-50 kg. The threshold was considered the central temperature triggering peripheral vasoconstriction, and significant vasoconstriction was defined as a forearm-fingertip skin-surface temperature gradient exceeding 4 degrees C. Thresholds were similar (approximately 35.7 degrees C) in each study group, suggesting that thermoregulatory responses to halothane anesthesia are similar in infants and children of differing weights. However, they were higher than expected based on the previously reported thresholds in pediatric patients given isoflurane anesthesia. After peripheral vasoconstriction, central temperature continued to decrease in patients weighing more than 30 kg but remained constant or increased slightly in the others. These data suggest that thermoregulatory responses are more effective in infants and small children than in bigger children or adults. In the second part of this study we evaluated the effect of caudal analgesia on the thermoregulatory threshold for vasoconstriction. Children undergoing hypospadias repair were anesthetized with halothane (0.9%) and oxygen. Following induction, they were randomly assigned to caudal analgesia (n = 7) or penile nerve block (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Caudal↗
PubMed1992

Cerebral pressure-flow velocity relationship during hypothermic cardiopulmonary bypass in neonates and infants.

To examine the effect of temperature on the relationship between cerebral perfusion pressure (CPP) and cerebral blood flow velocity (CBFV) and the effect of low-flow cardiopulmonary bypass (CPB) on cerebral perfusion, we studied 25 neonates and infants ranging from 3 to 210 days of age at three nasopharyngeal temperature (NPT) ranges during cardiopulmonary bypass. Pressure-flow velocity relationships were studied during normothermic (NPT = 36-37 degrees C), moderate hypothermic (NPT = 23-25 degrees C), and profound hypothermic (NPT = 14-20 degrees C) CPB. A transcranial Doppler monitor was used to obtain CBFV, which was measured in the M1 segment of the middle cerebral artery. The CBFV was used as an index of cerebral perfusion. Anterior fontanel pressure (AFP) was subtracted from mean arterial pressure (MAP) to calculate CPP in mm Hg. Nasopharyngeal temperature, PaCO2, and hematocrit were controlled during the study period. Arterial blood gases were analyzed at 37 degrees C, uncorrected for body temperature (alpha-stat acid-base management). The CBFV measurements were made over a range of CPP from 6 to 90 mm Hg. Using nonlinear regression analysis, we showed that cerebral pressure-flow velocity autoregulation was present during normothermic CPB (r2 = 0.68). Autoregulation became pressure-passive, using linear regression analysis, during moderate hypothermic CPB (r2 = 0.33) and profound hypothermic CPB (r2 = 0.69). Cerebral blood-flow velocity was not detectable at a mean (+/- SD) CPP of 9 (+/- 2) mm Hg induced by the low-flow CBP state but became apparent when CPP was increased to 13 (+/- 1) mm Hg (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1992

Temperature monitoring in pediatric anesthesia.

Thermoregulatory responses in infants and children are now fairly well understood. The phenomenon of heat loss in children during surgery is widely acknowledged. Hypothermia is most likely to occur during long surgical procedures in an air-conditioned operating room, particularly when respiration is controlled. Its consequences have prompted clinicians to take extra care in maintaining normothermia, especially in the very young. It is well known that anesthetized infants and children are capable of active thermoregulation and that their vasoconstrictive threshold differs little from that in adults [31]. Body temperatures can be measured using a variety of thermometers. Most clinically used thermometers are reasonably accurate. Perioperative hypothermia results from decreased metabolic heat production, increased environmental heat loss, redistribution of heat within the body, and anesthesia-induced inhibition of thermoregulation. Radiation and convection from the skin surface combine with evaporation from tissues inside surgical incisions to decrease mean body temperature. Perioperative hypothermia can be limited by prewarming the skin surface before induction of anesthesia, warming the operating room, humidifying the airway, and warming intravenous fluids.

Anesthesia, General↗
PubMed1991

Intracranial pressure and brain redox balance in rabbits.

The effects of elevated intracranial pressure (ICP) on intracellular oxygenation and cerebrocortical blood volume (CBV) were studied in rabbits. Intracellular oxygen (O2) concentration was assessed as the level of pyridine nucleotide concentration ([NADH]) oxidation/reduction balance and relative cerebrocortical blood volume (CBV) were measured with a fibreoptic fluororeflectometer probe placed on the cerebrocortical surface. Experiments were conducted in six urethane anaesthetized, normocarbic animals at different fractions of inspired O2 (FIO2). During gradual increases in ICP, [NADH] began to increase (representing decreased intracellular mitochondrial PO2) for all values of FIO2 as ICP exceeded a threshold of 18 +/- 2.2 cmH2O (P less than 0.05). The decline in intracellular oxygenation with elevated ICP was inversely related to FIO2 (P less than 0.05). With ICP greater than 18 +/- 2.2 cmH2O, intracellular mitochondrial oxygenation showed an improvement between an FIO2 of 0.21 and 0.5 (P less than 0.05) but increasing FIO2 from 0.5 to 1.0 resulted in no statistically significant improvement in tissue redox balance. The CBV, largely representing tissue capillary blood, increased when ICP reached greater 18 +/- 1.2 cmH2O probably reflecting local autoregulation or venous distension (P less than 0.05). However, above 30 +/- 1.1 cmH2O, CBV decreased (P less than 0.05). The results demonstrate the interdependence of inspired oxygen concentration, elevated ICP, and brain intracellular oxygenation, and suggest that brain oxygen utilization deteriorates above an ICP of about 18 cmH2O.

Animals↗
PubMed1991

Pyloric stenosis.

Infantile pyloric stenosis is the most frequently encountered infant gastrointestinal obstruction in most general hospitals. Although the primary therapy for pyloric stenosis is surgical, it is essential to realize that pyloric stenosis is a medical and not a surgical emergency. Preoperative preparation is the primary factor contributing to the low perioperative complication rates and the necessity to recognize fluid and electrolyte imbalance is the key to successful anaesthetic management. Careful preoperative therapy to correct severe deficits may require several days to ensure safe anaesthesia and surgery. The anaesthetic records of 100 infants with pyloric stenosis were reviewed. Eighty-five per cent of the infants were male (i.e., 5.7:1 male to female ratio) 12% were prematures. Surgical correction was undertaken at an average age of 5.6 wk, and the average weight of the infants at the time of surgery was 4 kg. A clinical diagnosis of pyloric stenosis by history and physical examination alone was made in 73% of the infants presenting to The Hospital for Sick Children. All the infants received general anaesthesia for the surgical procedure and there were no perioperative deaths.

Anesthesia↗
PubMed1991

Transcranial Doppler sonography: nitrous oxide and cerebral blood flow velocity in children.

To determine the effect of nitrous oxide (N2O) on cerebral blood flow velocity (CBFV) and cerebrovascular resistance index (RI+) in children, ten ASA physical status I or II patients aged one to eight years old, scheduled for urological procedures, were studied. Anaesthesia was induced with thiopentone 2 mg.kg-1, fentanyl 5 micrograms.kg-1 and diazepam 0.3 mg.kg-1. Muscular relaxation was ensured by using vecuronium 0.1 mg.kg-1. After tracheal intubation, anaesthesia was randomly assigned to either a mixture of air in oxygen (N2/O2) or 70% N2O in oxygen (N2O/O2) producing an FIO2 of 30%. Three sets of measurements of CBFV and RI+ were made with both gas mixtures. The CBFV and RI+ were measured in the middle cerebral artery (MCA) with a transcranial Doppler monitor. Measurements were made while using the initial gas mixture, then the second gas mixture was administered, and finally, the patient again was given the initial gas mixture. A continuous caudal epidural or lumbar epidural block was performed before skin incision. Neuromuscular blockade was maintained with vecuronium 0.05 mg.kg-1. Temperature, heart rate, end-tidal CO2, arterial oxygen saturation, haematocrit and arterial blood pressure were maintained constant. Ventilation was adjusted to achieve normocapnia. The CBFV increased when 70% N2/O2 was replaced by 70% N2O/O2 (P less than 0.05) while the CBFV decreased when 70% N2/O2 was readministered (P less than 0.05). Likewise, the CBFV decreased when 70% N2O/O2 was replaced by 70% N2/O2 (P less than 0.05) while the CBFV increased when 70% N2O/O2 was readministered (P less than 0.05).

Anesthesia, Inhalation↗
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↗