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Biomedical subjects

J Lerman

Publications and source records attributed to J Lerman.

At least 73 records · Page 4Linked to original sources
PubMed1993

Oral midazolam premedication for children with congenital cyanotic heart disease undergoing cardiac surgery: a comparative study.

To determine whether oral midazolam is a safe and effective alternative to our current standard premedication for children with cyanotic congenital heart disease (CCHD), 30 children aged 1-6 yr, scheduled for elective cardiac surgery, were studied. The children were randomly assigned to one of two groups: Group I received oral midazolam 0.75 mg.kg-1 30 min before separation from their parents in the surgical waiting area, and Group II received oral or rectal pentobarbitone 2 mg.kg-1 at 90 min, and morphine 0.2 mg.kg-1 and atropine 0.02 mg.kg-1 im at 60 min before separation. Heart rate, haemoglobin oxygen saturation (SpO2) and anxiolysis and sedation scores were recorded at four times during the study: at baseline (immediately before premedication), immediately after administration of the premedication, at separation of children from parents in the waiting area and at the time of application of the face mask in the operating room. We found that in Group I, anxiolysis improved at separation from parents compared with baseline (P < 0.05) and sedation increased both at separation and on mask application (P < 0.05), whereas in Group II anxiolysis did not change at any time and sedation increased only at separation (P < 0.05). Intramuscular injection of morphine produced a transient decrease in mean SpO2 (from 84% to 76%) (P < 0.05) that did not occur after ingestion of oral midazolam. The results of this study indicate that oral midazolam is a safe and effective replacement for the standard premedication for children with CCHD undergoing cardiac surgery and avoids the decrease in SpO2 associated with im injections.

Administration, Oral↗
PubMed1993

Are all preterm infants younger than 60 weeks postconceptual age at risk for postanesthetic apnea?

BACKGROUND: Preterm and ex-preterm infants are at risk for life-threatening apnea after general anesthesia. The authors attempted to define the postconceptual age beyond which apnea is less likely to occur and to identify the factors that predispose to postanesthetic apnea. METHODS: Ninety-one infants younger than 60 weeks postconceptual age undergoing 101 general anesthetics were prospectively studied. All infants were admitted to the hospital for cardiorespiratory monitoring overnight. The presence of coexistent medical conditions that could influence the incidence of apnea was determined by a review of current and previous medical records and by history. RESULTS: Of 38 procedures performed in 35 infants younger than 44 weeks postconceptual age, 10 (26.3%) procedures in 9 infants were associated with postanesthetic apnea. In eight of these, apnea did not resolve spontaneously: four infants required stimulation, and four required continuous positive airway pressure by face mask. Apnea occurred after 2 of 63 procedures performed in infants 44 weeks postconceptual age or older. Both episodes occurred in one patient who had neurologic disease. Of the remaining 61 procedures in the latter age group, 7 were associated with episodes of bradycardia (lowest heart rate was 79 beats/min) postoperatively without apnea. These episodes lasted up to 5 s, were not associated with apnea or cyanosis, and resolved spontaneously in all cases. All infants with postanesthetic apnea and/or bradycardia experienced their first episode within 12 h after surgery. CONCLUSIONS: Ex-preterm infants younger than 44 weeks postconceptual age are at greater risk for apnea after general anesthesia than are infants older than 44 weeks postconceptual age. Based on these results, the maximum long-run risk of postanesthetic apnea in preterm infants older than 44 weeks postconceptual age is 5% with 95% confidence.

Age Factors↗
PubMed1993

Dosing efficiency and particle-size characteristics of pressurized metered-dose inhaler aerosols in narrow catheters.

An experimental in vitro model was used to determine the effects of intraluminal catheter diameter and length on the delivered dose and particle-size characteristics of salbutamol (albuterol) aerosol delivered by metered dose inhaler (MDI) (Ventolin, 100 micrograms per puff). The dose of aerosolized drug that exited a 16-cm-long tracheal tube with an inner diameter (ID) of 6 mm was compared with that from 4 catheters of differing diameters and lengths that were inserted individually into the tracheal tube. The salbutamol MDI canister was actuated ten times into each delivery system, and the effluent aerosol was trapped onto a filter. The filtrate was dissolved in methanol, and the salbutamol concentration was determined using high-performance liquid chromatography. For the 3 22-cm-long catheters, the delivered dose (mean +/- SD) of salbutamol per actuation for the 22-standard wire gauge (SWG) catheter was 97.5 +/- 3.9 micrograms, which was similar to that for the 19-SWG catheter (102.3 +/- 2.5 micrograms) but was significantly less than that for the 14-SWG catheter (108.2 +/- 4.2 micrograms) (p < 0.05). These delivered doses exceeded those of the 6.0-mm-ID tracheal tube alone (2.33 +/- 0.76 micrograms) and the 13-cm-long 19-SWG catheter (2.17 +/- 0.29 micrograms) (p < 0.001). In a second experiment using a cascade impactor, the distribution of aerosol particle diameters that exited the 6-mm-ID tracheal tube was compared with that exiting a 13-cm-long 19-SWG catheter that extended halfway down the tracheal tube and with that exiting a 22-cm-long 19-SWG catheter inserted into the distal end of the 6-mm-ID tracheal tube. The mass median aerodynamic diameter (mean +/- SD) of the salbutamol aerosols delivered through both the 6.0-mm-ID tracheal tube (1.1 +/- 0.1 microns) and that of the 13-cm-long 19-SWG catheter (1.2 +/- 0.2 microns) were significantly less than that delivered through the 22-cm-long 19-SWG catheter (2.0 +/- 0.1 microns) (p < 0.05). The authors conclude that delivery of respirable aerosol can occur through narrow catheters that function as extended nozzles for MDIs. Optimal dosing will be obtained when the catheter extends the full length of the tracheal tube.

Aerosols↗
PubMed1992

Premedication of children with oral midazolam.

In a randomized, double-blind, placebo-controlled study, the safety, efficacy and feasibility of oral midazolam premedication in children were evaluated in an ambulatory surgery unit. Eighty unmedicated children (ASA PS I or II, ages 1-6 yr) were randomly assigned to one of four groups receiving midazolam 0.5, 0.75, or 1.0 mg.kg-1 or a placebo 30 min before separation from parents. Heart rate, systolic blood pressure, arterial oxygen saturation, respiratory rate, sedation and anxiolysis scores were recorded before premedication, every five minutes for 30 min and then during induction of anaesthesia and recovery. We found that heart rate, systolic blood pressure, arterial oxygen saturation and respiratory rate were unchanged during the study. Sedation and anxiolysis scores in the midazolam-treated groups were greater than those in the placebo group and that anxiolysis at the time of separation from the parents was judged excellent in 80-90% of the children who received midazolam. However, sedation and anxiolysis did not differ among the three midazolam groups. Mean times to discharge from hospital were similar for all four groups. The side effects, loss of balance and head control, blurred vision and dysphoric reactions were observed only in the 0.75 and 1.0 mg.kg-1 midazolam groups. We conclude that oral midazolam 0.5 mg.kg-1 is a safe and effective premedication and that 0.75 and 1 mg.kg-1 while offering no additional benefit, may cause more side effects.

Acoustic Stimulation↗
PubMed1992

Induction, maintenance and recovery characteristics of desflurane in infants and children.

To determine the induction and recovery characteristics of the new poly-fluorinated anaesthetic desflurane, 78 fasting and unpremedicated neonates, infants and children up to 12 yr of age were studied. Patients were stratified according to age: full-term neonates less than 28 days of age (n = 12), infants 1-6 mth (n = 12) infants 6-12 mth (n = 15), children 1-3 yr (n = 15), 3-5 yr (n = 12), and 5-12 yr (n = 12). After preoxygenation for two minutes and an awake tracheal intubation, neonates were anaesthetized with stepwise increases in the inspired concentration of desflurane in an air/oxygen mixture. Infants 1-12 mth of age and children were anaesthetized with stepwise increases in the inspired concentration of desflurane in oxygen. Their tracheas were intubated under deep desflurane anaesthesia without muscle relaxation. The incidence of airway reflex responses (including breathholding, coughing, laryngospasm, bronchospasm and oropharyngeal secretions), incidence of excitement, minimum arterial oxygen saturation, and times to loss of eyelash reflex and tracheal intubation during induction were recorded. After skin incision, anaesthesia was maintained with desflurane (approximately 1 MAC) in 60% nitrous oxide and oxygen. Heart rate and systolic arterial pressure were recorded awake, at approximately 1 MAC before and after skin incision and throughout surgery. At the completion of surgery, all anaesthetics were discontinued and the lungs were ventilated with 100% oxygen. During emergence, the end-tidal concentration of desflurane was recorded until extubation. The incidence of airway reflex responses and the times to eye opening and extubation after the discontinuation of desflurane were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia Recovery Period↗
PubMed1992

Adequacy of caudal analgesia in children after penoscrotal and inguinal surgery using 0.5 or 1.0 ml.kg-1 bupivacaine 0.125%.

To determine the optimal volume of bupivacaine 0.125% for postoperative caudal analgesia, we compared the effectiveness of 0.5 ml.kg-1 and 1 ml.kg-1 of bupivacaine 0.125% with 1:200,000 epinephrine in 80 children undergoing penoscrotal and inguinal surgery. The adequacy of caudal analgesia and supplemental analgesic requirements did not differ between the two groups at any time during the first 12 hr after surgery. We conclude that 0.5 ml.kg-1 of bupivacaine 0.125% with 1:200,000 epinephrine is as effective as 1 ml.kg-1 of the same solution and recommend its use for penoscrotal surgery. The evidence for effectiveness of 0.5 ml.kg-1 of bupivacaine 0.125% for inguinal surgery, however, is inconclusive because of an insufficient number of patients studied.

Analgesia, Epidural↗
PubMed1992

Haemodynamic and organ blood flow responses to sevoflurane during spontaneous ventilation in the rat: a dose-response study.

To determine the systemic haemodynamic and organ blood flow responses to the administration of sevoflurane during spontaneous ventilation, heart rate, cardiac index, mean arterial pressure, arterial blood gases, and blood flows to the brain, spinal cord, heart, kidneys and splanchnic organs were measured awake (control values) and after 30 min of anaesthesia with 0.5, 1.0, 1.2 or 1.5 MAC sevoflurane in rats. Cardiac output and organ blood flows were measured using radiolabelled microspheres. The MAC (mean +/- SEM) of sevoflurane was found to be 2.30 +/- 0.05%. At each concentration, haemodynamic variables were similar to awake values with the exception of a 12% reduction in mean arterial pressure at 1.5 MAC (P less than 0.01). Arterial PCO2 increased in a dose-related fashion. Cerebral and spinal cord blood flows increased at 1.2 and 1.5 MAC whereas coronary and renal blood flows did not change significantly. Portal tributary blood flow and preportal vascular resistance were unaffected. Hepatic arterial flow increased by 63% at 1.5 MAC (P less than 0.05) but total liver blood flow remained unchanged compared with awake values. In conclusion, the administration of sevoflurane during spontaneous ventilation produces a high degree of cardiovascular stability and maintains blood flow to major organs in the rat.

Anesthesia, Inhalation↗
PubMed1992

Factors affecting the rate of disappearance of sevoflurane in Baralyme.

The effects of temperature, water and Baralyme exhaustion on the rate of disappearance of sevoflurane in Baralyme were studied in an in vitro model. We found that the rate of disappearance of sevoflurane in Baralyme increased as the temperature increased and decreased as the concentration of water increased. The disappearance of sevoflurane also decreased in the presence of exhausted Baralyme compared with fresh Baralyme. The slower rate of disappearance of sevoflurane in Baralyme in the presence of water and Baralyme exhaustion suggests that the disappearance of sevoflurane may be self-limiting in the clinical setting.

Adsorption↗
PubMed1992

Hemodynamic and organ blood flow responses to halothane and sevoflurane anesthesia during spontaneous ventilation.

This study compared systemic hemodynamic and organ blood flow responses to equipotent concentrations of halothane and sevoflurane during spontaneous ventilation in the rat. The MAC values for halothane and sevoflurane were determined. Cardiac output and organ blood flows were measured using radiolabeled microspheres. Measurements were obtained in awake rats (control values) and at 1.0 MAC halothane or sevoflurane. The MAC values (mean +/- SEM) for halothane and sevoflurane were 1.10% +/- 0.05% and 2.40% +/- 0.05%, respectively. The PaCO2 increased to a similar extent in both groups compared with control values. During halothane anesthesia, heart rate decreased by 12% (P < 0.01), cardiac index by 26% (P < 0.01), and mean arterial blood pressure by 18% (P < 0.01) compared with control values. Stroke volume index and systemic vascular resistance did not change. During sevoflurane anesthesia, hemodynamic variables remained unchanged compared with control values. Coronary blood flow decreased by 21% (P < 0.01) and renal blood flow by 18% (P < 0.01) at 1.0 MAC halothane, whereas both remained unchanged at 1.0 MAC sevoflurane. Cerebral blood flow increased to a greater extent with halothane (63%; P < 0.01) than with sevoflurane (35%; P < 0.05). During halothane anesthesia, hepatic arterial blood flow increased by 48% (P < 0.01), whereas portal tributary blood flow decreased by 28% (P < 0.01). During sevoflurane anesthesia, hepatic arterial blood flow increased by 70% (P < 0.01) without a concomitant reduction in portal tributary blood flow. Total liver blood flow decreased only with halothane (16%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1991

Pharmacokinetics of lidocaine in children with congenital heart disease.

The purpose of this study was to determine the pharmacokinetics of lidocaine in children with congenital heart disease (CHD). Fifteen children with left to right intracardiac shunting of blood (acyanotic group) and 15 children with right to left intracardiac shunting of blood (cyanotic group) were studied and compared with 15 children without CHD (control group). Lidocaine (1.5 mg.kg-1) was injected into a peripheral vein over 30 sec and serial samples of arterial blood were obtained up to 120 min after completion of the infusion. Total and free lidocaine were analyzed by enzyme immunoassay. The serum concentration of alpha 1-acid glycoprotein (alpha 1-AGP) at induction of anaesthesia was measured in the three groups by radial immunodiffusion. The percent free lidocaine (100 x [free lidocaine]/[total lidocaine]) was greater at 30 sec post-infusion in all three groups (35-37%) than it was at any other time but was not significantly different among the three groups (P less than 0.05). There was no significant difference in either the percent free or the total lidocaine concentration at any sample time or in any of the pharmacokinetic variables among the three groups. The serum concentration of alpha 1-AGP did not differ significantly among the three groups of patients. We conclude that the presence of intracardiac shunts does not alter the pharmacokinetic behaviour of intravenous lidocaine (1.5 mg.kg-1) in children. The percent free lidocaine is greatest immediately post-injection and this may mitigate against rapid bolus administration of intravenous lidocaine in children.

Child, Preschool↗
PubMed1991

Is preoperative haemoglobin testing justified in children undergoing minor elective surgery?

The need for preoperative haemoglobin determination before the administration of general anaesthesia to paediatric patients has long been an issue for debate. This study was undertaken to determine the value of routine preoperative haemoglobin testing in paediatric patients scheduled for minor surgery. Two thousand patients ages one month to 18 yr scheduled for minor surgery were studied. The patients were grouped according to age, Group I less than or equal to yr, Group II 1-5 yr, Group III greater than 5 yr. The charts of patients whose preoperative haemoglobin concentration (Hb) was less than 100 g.L-1 were reviewed at a later date to determine the course of their anaesthesia and surgery. Eleven patients, all of whom were greater than 5 yr (0.5%), had a Hb less than 100 g.L-1. Of these, three patients, 27%, had their surgery deferred, whereas the remaining eight patients, 73%, underwent anaesthesia and surgery without complications. The three patients who were deferred returned for uneventful anaesthesia and surgery following oral iron therapy. We conclude that healthy paediatric patients five years and older scheduled for minor surgery do not require routine Hb determinations. Furthermore, the low incidence of anaemia and low deferral rate of anaemic children, 1-5 yr of age, lead us to question the value of preoperative Hb testing in this age group.

Adolescent↗
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

High-efficiency delivery of salbutamol with a metered-dose inhaler in narrow tracheal tubes and catheters.

We sought to determine the percent delivery by metered-dose inhaler (MDI) of a preparation of salbutamol (albuterol) to the distal end of either pediatric-size tracheal tubes or a narrow-gauge catheter. A bench model consisting of a swivel actuator; 3.0-6.0-mm ID tracheal tubes all 16 cm in length or a 19-G (standard wire gauge) catheter; mesh filters; and a continuous flow of dry air was used. Six actuations of salbutamol (100 micrograms each) were delivered during each experiment, and each experiment was repeated nine times. The delivery efficiency (DE) was the ratio of the net increase in weight of the filter, positioned at the distal end of the tracheal tube, to the net weight increase of the entire apparatus. We found that the DE (mean +/- SD) of salbutamol at the end of the tracheal tube was significantly less with a 3.0-mm ID tube (2.5 +/- 7.0%) than it was with a 4.0-mm (10.8 +/- 8.3%), 5.0-mm (10.7 +/- 7.2%), or 6.0-mm (12.3 +/- 8.4%) tube (P less than 0.05). To improve the DE of salbutamol aerosol, a 19-G catheter (0.7 mm ID) was inserted through the elbow connector and passed down the tracheal tube until the tip of the catheter approximated the distal tip of the tube. The DE of salbutamol in tracheal tubes (less than or equal to 12.3%) increased dramatically (97%; P less than 0.001) when a 19-G catheter was used. We conclude that the DE of salbutamol by MDI through 3.0-6.0-mm ID tracheal tubes is low but may be dramatically increased by actuating the canister into a 19-G distally placed catheter. Because of the increased efficiency of delivery, caution must be exercised when using a distally placed catheter to deliver MDI aerosols to patients.

Administration, Inhalation↗
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↗