Willis A. McGill

Induction and maintenance characteristics of anesthesia with desflurane and nitrous oxide in infants and children.

To determine the induction and maintenance characteristics of desflurane in pediatric patients, the authors anesthetized 206 infants and children aged 1 month to 12 yr with nitrous oxide plus desflurane and/or halothane in oxygen. Patients were assigned to one of four groups: anesthesia was 1) induced and maintained with desflurane after premedication with an oral combination of meperidine, diazepam, and atropine; 2) induced and maintained with desflurane; 3) induced with halothane and maintained with desflurane; or 4) induced and maintained with halothane. An unblinded observer recorded time to loss of consciousness (lid reflex), time to intubation, and clinical characteristics of the induction and maintenance of anesthesia. Moderate-to-severe laryngospasm (49%) and moderate-to-severe coughing (58%) occurred frequently during induction of anesthesia with desflurane; the incidence of these was not altered by premedication. In contrast, laryngospasm and coughing were rare during induction of anesthesia with halothane. In unpremedicated patients, time to loss of lid reflex (mean +/- SD) was similar for desflurane (2.4 +/- 1.2 min) and halothane (2.1 +/- 0.8 min). During induction of anesthesia, before laryngoscopy and intubation, mean arterial pressure less than 80% of baseline was more common with halothane; heart rate and mean arterial pressure greater than 120% of baseline were more common with desflurane. Intraoperatively, heart rate greater than 120% of baseline was more common with desflurane; blood pressures were similar for the two anesthetics. The authors conclude that the high incidence of airway complications during induction of anesthesia with desflurane limits its utility for inhalation induction in pediatric patients. Anesthesia can be safely maintained with desflurane if induced with a different anesthetic.

Comparison of three techniques for internal jugular vein cannulation in infants

Central venous cannulation allows accurate monitoring of right atrial pressure and infusion of drugs during the anaesthetic management of infants undergoing cardiopulmonary bypass. In this prospective, randomized study, we compared the success and speed of cannulation of the internal jugular vein in 45 infants weighing less than 10 kg using three modes of identification: auditory signals from internal ultrasound (SmartNeedle, SM), external ultrasound imaging (Imaging Method, IM) and the traditional palpation of the carotid pulsation and other landmarks (Landmarks Method, LM). The cannulation time, number of attempts with LM and SM techniques were greater than those with IM technique. The incidence of carotid artery puncture and the success rate were not significantly different among the three groups. In infants, a method based on visual ultrasound identification (IM) of the internal jugular vein is more precise and efficient than methods based on auditory (SM) and tactile perception (LM).

Age and the onset of desaturation in apnoeic children

Most patients undergoing general anaesthesia are apnoeic during laryngoscopy and tracheal intubation. This study determined the time until the onset of desaturation following preoxygenation in apnoeic infants, children, and adolescents. Fifty ASA physical status I patients, 2 days to 18 yr of age, were studied. The patients were stratified into one of five groups according to age: Group I, 0–6 mo; Group II, 7–23 mo; Group III 2–5 yr; Group IV, 6–10 yr; and Group V, 11–18 yr. Following induction of anaesthesia with halothane via mask or intravenous barbiturates, the ability of the anaesthetist to ventilate the lungs via the mask was ascertained and paralysis was accomplished with vecuronium 0.1 mg · kg−1. Manual mask ventilation was maintained with oxygen and halothane. When end-tidal N2 decreased below 3% (minimum time two minutes), the face mask was removed. The time between the removal of the face mask and a decrease in oxygen saturation (SpO2 from 99–100% to 90% was measured. Manual ventilation was then resumed and the trachea intubated. Desaturation started earlier in infants than in two-to five-year-old children (96.5 ± 12.7 sec vs 160.4 ± 30.7 sec, P < 0.0001). Children became desaturated faster than adolescents (160.4 ± 30.7 vs 382.4 ± 79.9 sec, P < 0.0001). The time required to reach 90% saturation correlated well with age by linear regression analysis (r2 = 0.88, P < 0.0001). We conclude that the time to onset of desaturation following pre-oxygenation with mask ventilation increases with age in healthy apnoeic children. Adolescents can tolerate apnoea for longer than children, and infants exhibit desaturation faster than children.RésuméLa plupart des patients demeurent en apnée pendant la laryngoscopie et l’intubation. Cette étude précise l’intervalle qui précède la désaturation après préoxygénation chez les nouveaunés, les enfants et les adolescents. Cinquante patients ASA I, âgés de deux jours à dixhuit ans, font partie de l’étude. Les patients sont répartis en cinq groupes selon leur âge: groupe I, 0–6 mois, groupe II, 7–23 mois; groupe III, 2–5 ans; groupe IV, 6–10 ans; groupe V, 11–18 ans. Après une induction au masque à l’halothane ou aux barbituriques intraveineux, l’habileté de ventiler les poumons au masque est constatée et la paralyse initiée avec du vécuronium 0,1 mg · kg−1. La ventilation manuelle au masque est maintenue avec de l’oxygène et de l’halothane. Quand le N2 télé- expiratoire diminue sous 3% (en deux minutes au minimum), le masque est enlevé. On mesure l’intervalle entre le retrait du masque et une baisse de la saturation en oxygène (SpO2 de 99–100% à 90%. On reprend la ventilation manuelle et la trachée est intubée. La désaturation débute plus rapidement dans les deux premiers groupes que chez les enfants de deux à cinq ans (96,5 ± 12,7 s vs 160,4 ± 30,7 s, P< 0,0001). Les enfants désaturent plus rapidement que les adolescents (160,4 ± 30,7 vs 382,4 ± 79,9 s, P < 0,0001). Le temps nécessaire à l’atteindre 90% de désaturation présente une bonne corrélation avec l’âge comme le montre l’analyse de régression linéaire (r2 = 0,88, P < 0,0001). Nous concluons que l’intervalle qui précède la désaturation après la préoxygénation avec ventilation au masque augmente avec l’âge chez les enfants apnéiques en bonne santé. Les adolescents peuvent tolérer l’apnée plus longtemps que les enfants et les nourissons se désaturent plus rapidement que les enfants.

PROPOFOL : EFFECTIVE DOSE AND INDUCTION CHARACTERISTICS IN UNPREMEDICATED CHILDREN

The induction dose, induction characteristics, and cardiovascular and respiratory effects of propofol were studied in 90 unpremedicated children 3-12 yr old. Propofol in a dose of 1-3 mg.kg-1 was injected in an antecubital vein over 10-30 s. Successful induction was defined by loss of eyelash reflex occurring within 50 s of the conclusion of propofol injection and followed by subsequent acceptance of face mask without excessive movement. The effective dose of propofol resulting in loss of eyelash reflex in 50% (ED50) and 95% (ED95) of children were 1.3 (1.1-1.4) and 2.0 (1.7-2.6) mg.kg-1 (95% confidence interval). The corresponding ED50 and ED95 for a successful induction that included acceptance of face mask were 1.5 (1.3-1.7) and 2.3 (2.1-3.0), respectively. There was a 6.6% incidence of mild to moderate pain on injection and a 12.7% incidence of involuntary movement. Apnea (cessation of breathing greater than 20 s) was seen in 21% of patients. Blood pressure decreased by more than 20% of baseline value in 48% of patients who received halothane (1-3%) after the bolus injection of propofol. It is concluded that propofol is an effective induction agent in children. A dose of 2.5-3.0 mg.kg-1 is recommended to ensure a smooth transition to an inhalational maintenance technique. The use of antecubital veins is associated with a low incidence of pain on injection.

Bronchial obstruction by transesophageal echocardiography probe in a pediatric cardiac patient

N ‘ewer monitoring advances-despite the label ’‘noninvasive’’-often present significant risks. Transesophageal echocardiography (TEE) provides a wealth of new cardiovascular information not previously available to operating room physicians, yet requires a bulky probe inserted in juxtaposition to the patient’s airway. We report a case of bronchial airway obstruction during routine use of a TEE probe in a child undergoing cardiac surgery.

Subacute Upper Respiratory Infection in Small Children

Although it is widely accepted as good practice to avoid elective administration of general anesthesia to a patient who has an acute upper respiratory infection (URI), there is a paucity of information regarding the nature of the morbidity that may result if anesthesia were administered. Furthermore, the optimal period of recovery from the URI that should be allowed prior to considering the patient a candidate for an elective surgical procedure has not been defined. The following are two case reports which are representative of 11 patients who developed unexplained intra-anesthetic pulmonary dysfunction. The common factor in all but one patient was a history of an upper respiratory infection during the previous month.

Changes in heart rate and rhythm after intramuscular succinylcholine with or without atropine in anesthetized children.

The effects of intramuscular injections of Succinylcholine with or without atropine on heart rate and rhythm were studied in 50 unpremedicated children 6–18 months of age. All had anesthesia induced with N2O-O2 and halothane 2% by face mask. Sixty seconds later, one of four study drugs or drug combinations was injected into the deltoid muscle of patients in groups 1–4. Following injection, halothane concentration was reduced to 1%, and ventilation was controlled. Patients given atropine only (0.02 mg/kg), succinylcholine only (4 mg/kg), or a combination of both (4 mg/kg Succinylcholine plus 0.02 mg/kg atropine) showed transient increases in heart rate to 106 ± 7.5%, 113 ± 11.8%, and 109 ± 20.1% (mean ± so) of control, followed by a decrease to 78 ± 6.7%, 79 ± 9.4%, and 80 ± 10.5%, respectively, in 2–3 min after injection. Patients given a combination of Succinylcholine (4 mg/kg) plus a higher dose of atropine (0.03 mg/kg) also had a transient increase in heart rate to 107 ± 7.5%, followed by a decrease to 82 ± 11.8% 2 min after injection. However, this group differed from the other three groups in presenting a second, prolonged increase in heart rate to 115 ± 9.0% of preinjection levels. Patients in group 5 (controls) received no injections. Their heart rate decreased to 76 ± 10.78% of preinduction level within 90 sec of induction, and remained unchanged thereafter. We conclude that Succinylcholine (4 mg/kg) can be used intramuscularly with or without atropine (0.02 mg/kg) in lightly anesthetized young children without producing severe bradycardia. If an increase in heart rate is desired, a higher dose of atropine (0.03 mg/kg) is recommended.

Anesthesia for fucosidosis.

Fucosidosis is an extremely rare, autosomal recessive lysosomal storage disease, characterized by a deficiency of the lysosomal hydrolase alpha fucosidase. We report a case of a 6‐year‐old child, diagnosed with fucosidosis type 2, who presented for dental rehabilitation under general anesthesia. Anesthesia was uneventful. Features of fucosidosis are discussed

Time-weighted averaging for nitrous oxide: an automated method.

An automated method of obtaining a time-weighted average of nitrous oxide levels in an operating room was compared with a standard method. The automated method consisted of electronic integration of the voltage output of a nitrous oxide analyzer using a multimeter-microprocessor. The standard method utilized a bag and pump to collect a room air sample, which was subsequently analyzed with a nitrous oxide analyzer. There was a high degree of correlation (r = 0.99) between the two methods. It is concluded that the automated method is an accurate alternative and offers institutions a simple, cost-effective method of monitoring and documenting results of pollution control programs in anesthetizing locations.

Ultrasonography for Cannulation of Internal Jugular Vein in Infants - A Superior Technique? • 237

Ultrasonography for Cannulation of Internal Jugular Vein in Infants - A Superior Technique? • 237