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Biomedical subjects

J Lerman

Publications and source records attributed to J Lerman.

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

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↗
PubMed1991

Minimum alveolar concentration of desflurane and hemodynamic responses in neonates, infants, and children.

We sought to determine the minimum alveolar concentration (MAC) and hemodynamic responses to desflurane in 72 fasting and unpremedicated full-term neonates, infants, and children up to 12 yr of age. The patients were divided into six groups (n = 12) according to age. After awake tracheal intubation, neonates were anesthetized with desflurane in oxygen and air. Infants greater than 1 month of age and all older children were anesthetized with desflurane in 100% oxygen, and their tracheas were intubated without muscle relaxation. MAC was determined using the "up-and-down technique" and logistic regression. Heart rate and systolic arterial pressure were recorded awake, at approximately 1 MAC desflurane before skin incision and at approximately 1 MAC during the peak hemodynamic responses to skin incision. We found that the relationship between MAC (mean +/- standard deviation) as determined by the up-and-down technique and age was quadratic, reaching a maximum value in infants 6-12 months of age: in neonates 0-1 month MAC was 9.16 +/- 0.02%, in infants 1-6 months 9.42 +/- 0.06%, in infants 6-12 months 9.92 +/- 0.44%, in children 1-3 yr 8.72 +/- 0.59%, in children 3-5 yr 8.62 +/- 0.45%, and in children 5-12 yr 7.98 +/- 0.43%. MAC values obtained using logistic regression were similar. Heart rate decreased an average of 16% before skin incision in infants 6-12 months of age and children 1-3 and 3-5 yr of age when compared to awake values (P less than 0.025) but did not change significantly in the remaining three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

[Is there a clinical value of endomyocardial biopsy and immunosuppressive treatment in idiopathic dilated cardiomyopathy? Study by meta analysis].

This study was intended to answer two questions: 1) whether the prognosis of patients with dilated cardiomyopathy and myocardial inflammatory changes, and 2) whether immunosuppressive agents may modify survival. The meta-analysis technique was employed as a tool in order to homogenize the results of several reports that were not conclusive and often contradictory due to the small number of patients studied. Twenty one reports were included; in 12, there was a follow up study of patients with acute inflammatory changes. Four reports compared the follow up of groups showing acute inflammatory changes with controls with dilated cardiomyopathy lacking inflammatory phenomena in the biopsy, including a total of 272 patients; 47 (17.3%) disclosed inflammatory changes. Total mortality for this group was 25.6% while that for the control group was 28.4% (p = NS). Thirteen reports dealt with the effect of immunosuppressive treatment with myocarditis; 7 studies included an untreated control group, summing up 119 patients. Mortality did not differ between these groups: 31.3% and 30.9%, respectively (p = NS). It is concluded that 1) there are very few controlled and conclusive reports available on the prognostic value of endomyocardial biopsy and immunosuppressive treatment in idiopathic dilated cardiomyopathy; 2) the presence of inflammatory changes did not worsen the prognosis; and 3) immunosuppressive treatment did not improve survival.

Biopsy↗
PubMed1990

Accuracy of end-tidal PCO2 measurements using a sidestream capnometer in infants and children ventilated with the Sechrist infant ventilator.

To determine the accuracy of end-tidal PCO2 (PETCO2) measurements analyzed with a sidestream capnometer in infants and children whose lungs were ventilated with a Sechrist infant ventilator and an Ayre's t-piece, we compared PETCO2 measurements obtained from the proximal (PETCO2-p) and distal (PETCO2-d) ends of the tracheal tube to arterial PCO2 (PaCO2) in 37 healthy infants and children between 1.3 and 24.5 kg. Both PETCO2-p and PETCO2-d accurately approximated PaCO2, however, the mean (+/- SD) arterial to end-tidal PCO2 difference (delta(a-ET)PCO2) was significantly greater with proximal (1.27 +/- 1.54 mmHg) than with distal sampling (0.64 +/- 1.64 mmHg) (P less than 0.01). In the subgroup of patients who weighted less than 12 kg, the delta(a-ET)PCO2 using proximal gas sampling (1.94 +/- 1.29 mmHg) was also significantly greater than it was using distal sampling (0.74 +/- 1.31 mmHg) (P less than 0.001). We conclude that although statistically different, both proximal and distal estimates of PETCO2 provide acceptable estimates of PaCO2 in healthy infants and children who are ventilated with a Sechrist infant ventilator and an Ayre's t-piece system.

Carbon Dioxide↗
PubMed1990

End-tidal carbon dioxide measurements in critically ill neonates: a comparison of side-stream and mainstream capnometers.

To determine whether end-tidal PCO2 (PETCO2) measurements obtained with two infrared capnometers accurately approximates the arterial PCO2 (PaCO2) in critically ill neonates, simultaneous measurements of PETCO2 were obtained from the distal and proximal ends of the tracheal tube with a sidestream capnometer (Puritan Bennett/Datex--BP/D) and from the proximal end with a mainstream capnometer (Hewlett-Packard-HP) in 20 intubated neonates. Distal sidestream PETCO2 and mainstream PETCO2 correlated with the PaCO2 (r2 = 0.66 and 0.61, respectively) within the range of 26-57 mmHg PaCO2. However, proximal PETCO2 with the sidestream capnometer correlated very poorly (r2 = 0.09) with PaCO2. The slope of the least square regression line for the distal sidestream capnometer, 0.67, was significantly less than that for the mainstream capnometer, 0.78 but both were significantly greater than that for the proximal sidestream capnometer, 0.39 (P less than 0.05). The slope of the regression for the proximal sidestream capnometer did not differ significantly from horizontal. Insertion of the mainstream sensor for the HP capnometer significantly increased the transcutaneous CO2 when compared with preinsertion values. We conclude that both distal sidestream and mainstream capnometry provide accurate estimates of the PaCO2 in critically ill neonates.

Carbon Dioxide↗
PubMed1990

Alpha 1-acid glycoprotein and the binding of lidocaine in children with congenital heart disease.

The purpose of this study was to evaluate the effect of congenital heart disease (CHD) on the serum concentrations of alpha 1-acid glycoprotein (alpha 1-AGP) and the serum binding of lidocaine. Thirteen children with acyanotic CHD and 12 children with cyanotic CHD were studied and compared with 28 children without heart disease (control). The mean (+/- SD) serum concentration of alpha 1-AGP, as determined by radial immunodiffusion, did not differ significantly among the three groups. Five minutes after administration of 1.5 mg.kg-1 intravenous lidocaine, the free fraction of lidocaine correlated inversely and linearly with the serum concentration of alpha 1-AGP in children with acyanotic CHD (r2 = 0.74; P less than 0.001) cyanotic CHD (r2 = 0.57; P less than 0.005), and control (r2 = 0.63; P less than 0.001). The slopes and intercepts of the linear regressions did not differ significantly among the three groups. We conclude that the serum concentration of alpha 1-AGP in children with CHD does not differ quantitatively or qualitatively from that in children without CHD.

Adolescent↗
PubMed1990

Effects of ranitidine and metoclopramide on gastric fluid pH and volume in children.

To determine the effects of ranitidine and metoclopramide on gastric fluid in children, 40 healthy children (aged 2-8 yr) were allocated randomly to groups of 10 to receive one of four oral premedications 4 h before surgery: no premedication, metoclopramide 0.1 mg kg-1, ranitidine 2 mg kg-1 and metoclopramide 0.1 mg kg-1 with ranitidine 2 mg kg-1. After tracheal intubation, gastric fluid was aspirated and analysed for pH and total fluid volume. Ranitidine, with or without metoclopramide, increased gastric fluid pH significantly compared with control (P less than 0.05). Gastric fluid volume did not change significantly.

Child↗
PubMed1990

The blood/gas solubilities of sevoflurane, isoflurane, halothane, and serum constituent concentrations in neonates and adults.

To determine the effect of prematurity on the solubility of volatile anesthetics in blood, the authors measured the blood/gas partition coefficients of sevoflurane, isoflurane, and halothane and the serum concentrations of albumin, globulin, cholesterol, and triglycerides in umbilical venous blood from ten preterm and eight full-term neonates and in venous blood from eight fasting adult volunteers. The authors found that the blood/gas partition coefficient of sevoflurane did not differ significantly among the three age groups. The partition coefficients of isoflurane and halothane in preterm neonates did not differ significantly from those in full-term neonates. However, the partition coefficients of both anesthetics in neonates were significantly less than those in adults. The blood/gas partition coefficients of the three volatile anesthetics in preterm neonates did not change significantly with gestational age. The blood/gas partition coefficients of sevoflurane, isoflurane and halothane for all three age groups combined correlated only with the serum concentration of cholesterol. The authors conclude that the blood/gas partition coefficients of isoflurane, halothane, and sevoflurane in preterm neonates are similar to those in full term neonates and that gestational age does not significantly affect the blood/gas solubility.

Adult↗
PubMed1990

The minimum alveolar concentration (MAC) and hemodynamic effects of halothane, isoflurane, and sevoflurane in newborn swine.

To determine the minimum alveolar concentration (MAC) and hemodynamic responses to halothane, isoflurane, and sevoflurane in newborn swine, 36 fasting swine 4-10 days of age were anesthetized with one of the three volatile anesthetics in 100% oxygen. MAC was determined for each swine. Carotid artery and internal jugular catheters were inserted and each swine was allowed to recover for 48 h. After recovery, heart rate (HR), systemic systolic arterial pressure (SAP), and cardiac index (CI) were measured awake and then at 0.5, 1.0, and 1.5 MAC of the designated anesthetic in random sequence. The (mean +/- SD) MAC for halothane was 0.90 +/- 0.12%; the MAC for isoflurane was 1.48 +/- 0.21%; and the MAC for sevoflurane was 2.12 +/- 0.39%. Awake (mean +/- SD) measurements of HR, SAP, and CI did not differ significantly among the three groups. Compared to the awake HR, the mean HR decreased 35% at 1.5 MAC halothane (P less than 0.001), 19% at 1.5 MAC isoflurane (P less than 0.005), and 31% at 1.5 MAC sevoflurane (P less than 0.005). Compared to awake SAP, mean SAP measurements decreased 46% at 1.5 MAC halothane (P less than 0.001), 43% at 1.5 MAC isoflurane (P less than 0.001), and 36% at 1.5 MAC sevoflurane (P less than 0.005). Mean SAP at 1.0 and 1.5 MAC halothane and isoflurane were significantly less than those measured at equipotent concentrations of sevoflurane (P less than 0.005). Compared to awake CI, mean CI measurements decreased 53% at 1.5 MAC halothane (P less than 0.001) and 43% at 1.5 MAC isoflurane (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Effects of duration of fasting on gastric fluid pH and volume in healthy children.

To determine the effects of duration of fasting before elective surgery on gastric fluid pH and volume in children, a prospective, randomized, blinded study of 100 unpremedicated children, aged 1-14 yr, was undertaken. Each child was given 2 mL/kg of water orally and then fasted 2, 4, or 6 h preoperatively. After induction of anesthesia and tracheal intubation, gastric fluid was aspirated through a large-bore, multiorifice orogastric tube. Gastric fluid pH was measured using a calibrated PHM62 radiometer. Gastric fluid volume was the total volume of fluid aspirated from the stomach. The duration of fasting was between 2.0 and 8.5 h. We found that neither gastric fluid pH nor gastric fluid volume correlated with the duration of fasting. The mean (+/- SD) gastric fluid pH was 1.80 +/- 0.79 and the mean (+/- SD) gastric fluid volume was 0.56 +/- 0.39 mL/kg. Gastric fluid pH was less than 2.5 and volume greater than 0.4 mL/kg in 53% of children. We conclude that healthy children may receive 2 mL/kg of water up to 2 h before elective surgery without decreasing gastric fluid pH or increasing gastric fluid volume beyond values obtained after fasting for 6 h.

Adolescent↗
PubMed1990

Thiopental attenuates dysrhythmias in children: comparison of induction regimens.

Anesthesia was induced in 91 children using one of three induction regimens: (a) thiopental, atropine, and succinylcholine (T group); (b) halothane, atropine, and succinylcholine (H group); and (c) halothane, thiopental, atropine, and succinylcholine (H/T group). The incidence of dysrhythmias was significantly greater in the H group (85%) than in the T group (6%) and H/T group (20%). Fewer dysrhythmias occurred in the H/T group compared to the H group despite similarly prolonged QTc intervals in both groups. We conclude that induction of anesthesia with thiopental is appropriate and reduces the incidence of cardiac rhythm disturbances in children and that administration of thiopental to children during induction of anesthesia with halothane, atropine, and succinylcholine may reduce the incidence of cardiac dysrhythmias.

Anesthesia, General↗