Kenneth A. Haselby

Respiratory obstruction from uvular edema in a pediatric patient.

A 20-month-old 10.8-kg boy was admitted as an outpatient for electroretinography under general anesthesia. He had an uneventful anesthetic with tracheal intubation at age 6 months for electroretinography. There was no family history of anesthesia-related problems. He had no known allergies and was receiving no medicines. He had a recent history of mild coryza without other evidence of upper respiratory tract infection. Preoperative physical examination and complete blood count were normal except for mild coryza. After establishment of an intravenous infusion and the intravenous administration of atropine, anesthesia was induced with thiopental followed by succinylcholine. After ventilation with 100% oxygen by mask, the trachea was intubated uneventfully with a 4.0-mm inside diameter orotracheal tube. Anesthesia was maintained with halothane and nitrous oxide-oxygen using assisted ventilation. At the conclusion of the 50-min procedure, the anesthetic gases were discontinued, and after demonstration of the presence of protective airway reflexes, the pharynx was suctioned and the trachea extubated. The chdd was taken to the recovery room and placed in a mist tent with an F I ~ ~ of 0.26. The recovery room course was uneventful, and after a 45-min stay, he was dressed and carried in an upright position to an adjacent waiting area. Forty-five minutes later as the child was moved from a recumbent to upright po-

Comparison of cardiovascular effects of thiopental and pentobarbital at equivalent levels of CNS depression.

Thiopental and pentobarbital have been used in high doses to protect the brain from injury following hypoxia or to reduce intracranial pressure. This study was performed to determine whether these barbiturates differ in cardiovascular effects when present in plasma concentrations that produce equivalent CNS effects. The effects of thiopental and pentobarbital on heart rate, stroke volume/kg, cardiac output/ kg, systemic vascular resistance, mean arterial pressure, and central venous pressure were statistically indistinguishable at plasma concentrations of each barbiturate ranging from 50% to 100% of their concentration producing EEG silence. Three of the seven dogs given thiopental developed ventricular bigeminy at plasma concentrations ranging from 45% to 65% of their concentration producing EEG silence. Lidocaine (1.4--2.0 mg/kg intravenously) reversed the bigeminy to sinus rhythm. When given more than the amount needed to produce a flat EEG, five of the seven dogs given thiopental died, but all dogs given pentobarbital survived. Pentobarbital may be a better choice than thiopental when large doses are indicated.

Effect of thiopental and succinylcholine on serum potassium concentrations in children.

Succinylcholine increases serum potassium levels in normal adults by 0.25-0.8 mEq/L (1,2). The magnitude of the increase in potassium is decreased when thiopental or methohexital are used for induction of anesthesia (3,4). Pretreatment with diazepam, hexafluorenium, pancuronium, or fazadinium also prevents succinylcholine-induced serum increases in potassium (2,5-7). Henning and Bush found that after halothane induction of anesthesia, succinylcholine increased serum potassium by a mean of 0.45-0.48 mEq/L in children (8). Keneally and Bush reported that potassium increased by an average of 0.23 mEq/L following succinylcholine after thiopental induction (4 mg/kg) in children less than 5 yr old (9). There were no significant changes in children 6-16 yr old. In these studies of children, premedication was not controlled and alveolar ventilation was not monitored. In the present study we examined the effects of succinylcholine on venous serum potassium concentrations after thiopental induction (6 mgkg) of general anesthesia in healthy, unpremedicated children. Ventilation was controlled to maintain end-tidal C02 within the normal range.

Anaesthetic implications of neonatal necrotizing enterocolitis

A retrospective analysis of infants with necrotizing enterocolitis was done to evaluate the effects of preoperative abnormalities upon anaesthesia and mortality. Mortality was significantly increased in infants weighing less than 1500 grams (p < .001). Sixty-nine per cent of the infants had hyaline membrane disease and 35 per cent had platelet counts less than 50 x 109 cells/litre (50,000/mm3). Perioperative problems include peritonitis, sepsis, hypovolaemia, acidosis, and prematurity. Other ramifications of prematurity and anaesthesia are discussed.RésuméLes auteurs ont fait la revision des dossiers de trente deux enfants opérés pour entéro-colite nécrosante du nouveau-né. Le but de l’étude était de mettre en évidence l’impact des anomalies pré-opératoires sur la mortalité et la conduite de l’anesthésie. La mortalité totale a été de 53 pour cent (17/32). On a observé entre autres: 1) une mortalité plus élevée (p < 0.001) chez les bébés de moins de 1500 g. 2) un syndrome de membrane hyaline chez 69 pour cent des patients et 3) un décompte plaquettaire inférieur à 50 x 109/litres (50,000/mm3) dans 35 pour cent des cas. Parmi les principaux problèmes péri-opératoires, on a relevé la péritonite, l’état septique, l’hypovolémie, l’acidose et la prématurité. La conduite de l’anesthésie et les problèmes liés à la prématurité sont discutés.

A gravity-driven continuous flush system for vascular catheters.

flow of blood into the pressure monitoring line and transducer. These flush devices can also result in a false elevation of the monitored pressure (4). These hazards are of considerable significance in the infant and small child. To obviate the hazards of the currently used pressurized system we have constructed a gravity-driven source of high pressure flush soluA Gravity-Driven Continuous Flush System for Vascular Catheters

Anesthetic Considerations for Ophthalmic Surgery in the Pediatric Patient

In conclusion our review of 2,187 ophthalmic procedures revealed that even the very young pediatric patient can be anesthetized safely by adhering to basic principles and meticulous attention to detail.

Comparative measurements of left-ventricular performance produced by rapid changes in blood volume in dogs

Left-ventricular function was evaluated in 11 open-chest dogs under pentobarbital anesthesia. Ventricular performance was altered by infusing or withdrawing crossmatched blood, and simultaneous recordings obtained of left-atrial pressure, leftventricular pressure, aortic flow, and aortic pressure. From these recording were obtained the stroke volume, stroke work, peak ventricular power, and the maximal rate of change of aortic flow and ventricular pressure. The derived variables were plotted versus end diastolic pressure to provide ventricular-function curves. The curves were obtained during a control state, during norepinephrine infusion, and subsequent to aortic constriction at the level of the coronary ostia. Studies were done in the heart-rate paced and nonpaced animal; the data were presented in terms of per cent change from control values. Peak power and stroke work provided the more classical type of ventricular-function curves and it is suggested that these provide the most useful information. Pressure-derivative curves were the most widely separated. Similar studies were repeated in seven animals in which afterload was controlled at 100 mm Hg. Curve shape was somewhat altered but overall changes were comparable.

Effect of age on epinephrine-induced arrhythmias during halothane anaesthesia in pigs

The effect of age on the arrhythmogenicity of epinephrine during halothane anaesthesia was studied in pigs of two different age groups. At a stable alveolar concentration of 0.84 volumes per cent halothane, ventricular arrhythmias could not be elicited in one- to three-day-old pigs by a 100μg·kg-1 infusion of epinephrine. PVCs were pro-duced in 50- to 55-day-old pigs at a mean epinephrine dose of 9.55 μ·kg-1. Heart rate, systolic blood pressure, and rate-pressure product were significantly higher before and during the epinephrine infusion in the 50- to 55-day-old pigs. It is concluded that there is an age dependent effect upon epinephrine induced arrhythmias during halothane anaesthesia in pigs.RésuméOn a étudié l’arythmogénicité de la combinaison épinephrinefhalothane chez des porcs d’d’ges différents. Sous anesthésie stable, à 0.84 vol% d’halothane alvéolaire, aucune arythmie ventriculaire n’a pu être déclenchée par l’infusion de 100 μg·kg-1 d’épinéphrine chez des porcs âgés d’un à trois jours; d’autre pan, chez des porcs âgés de 50 à 55 jours, des extrasystoles ventriculaires ont pu être déclenchées à des doses moyennes d’épinéphrine de 9,55 μg·kg-1. La fréquence cardiaque, la pression artérielle et le produit fréquencelpression étaients plus élevés de façon significative avant et pendant l’infusion d’épinéphrine. On en conclut que l’âge de l’animal joue un rôle dans la genèse des arythmies attribuables à la combinaison épinéphrine/halothane.

Dopamine reverses cardiovascular depression of toxic doses of pentobarbitone in dogs

Pentobarbitone, 20 mg.kg-1 IV followed by infusion of 25 mg.kg-1.hr-1, produced a progressive decrease in mean arterial pressure in dogs from 113 ± 17mmHg (SD) after one hour of infusion to 82 ±21 mmHg after3.5 hours and to 49 ± 22 mmHg after 5.5 hours. EEG silence occurred at 3.6 ± 0.6 hours. In dogs similarly treated with pentobarbitone, a two hour infusion of dopamine 5.µg.kg-1.min-1 beginning at the time of EEG silence prevented the further decrease in pressure and restored pressure to 87 ± 18 mmHg.The mechanism for this effect of dopamine was an increase in cardiac output as systemic vascular resistance was unaffected by dopamine. The cardiac output increase was mainly the result of an increase in stroke volume as heart rate increased only slightly. Since reduced stroke volume was the main reason why pentobarbitone lowered blood pressure, the effect of dopamine on stroke volume and thus on blood pressure makes it an appropriate antagonist to the cardiovascular effects of toxic doses of pentobarbitone.RésuméLe pentobarbitone administré à hautes doses (20 mg.kg-1, dose d’attaque suivie d’une infusion de 25 mg.kg-1 par heure) à des chiens a produit une diminution progressive de la pression artérielle moyenne. En effet, chez les animaux ainsi traités la pression artérielle moyenne est passée de 113 ± 17 mmHg après une heure d’infusion à82±21 mmHg après trois heures et demie et à 49 ± 22 mmHg après cinq heures et demie de ce traitement. Le silence encéphalographique s’est établi après 3.6 ± 0.6 hre. Chez d’autres chiens traités de la même façon au pentobarbitone, une infusion de dopamine 5 µg.kg-1par minute pendant deux heures, commencée au début du silence électroencéphalographique, a stoppé la descente de la pression artérielle et l’a rétablie à 87 mmHg ± 18.C’est par l’augmentation du débit cardiaque que cet effet s’est manifesté car les résistances vasculaires systémiques n’ont pas été modifées par la dopamine. Cette augmentation de débit cardiaque était surtout le résultat d’une augmentation du volume d’éjection car la fréquence cardiaque s’est à peine modifiée. Comme c’est par réduction du volume d’éjection que le pentobarbitone avait diminué la pression artérielle, la dopamine, en rétablissant le volume d’éjection, apparaît donc d’un choix judicieux pour contrer les effets cardiovasculaires indésirables de doses toxiques de pentobarbitone.

Elimination of Hemorrhage Following Right Atrial Catheter Removal: A Simple Technique

A simple technique to prevent postoperative bleeding following removal of a right atrial catheter is described. This technique involves reinforcing the catheter exit site with a Silastic Vesseloop.