Avron Y. Sweet

Study of ketamine as an obstetric anesthetic agent

Abstract Ketamine [2-(o-chlorophenyl)-2-(methylamino) cyclohexanone monohydrochloride], a new short-acting anesthetic agent which does not inhibit laryngeal or pharyngeal reflexes, has been studied in 14 pregnant subjects and 18 nonpregnant controls. Approximate clearances calculated indicated a reduced clearance in pregnant subjects (48 cf. 64 ml. per minute per kilogram). Side effects included a 30 to 40 per cent increase in systolic and diastolic blood pressure, an increase in pulse and respiration, salivation, and nausea, and vivid but usually pleasant dreams. The fetal pH did fall after administration of anesthesia, but remained in the normal range along with Pco 2 and Pco 2 . Intrauterine tone increased, and there were changes in fetal heart rate, but none that might not have occurred with advancing labor. Newborn infants were not unduly depressed if the dose was kept below a priming dose of 1.5 mg. per kilogram followed by infusing 0.08 mg. per kilogram per minute. Serum bilirubin concentrations in the newborn infant were slightly increased and could not be accounted for. Mothers and babies all went home at the expected time post partum in apparent good health.

Total lipids and the lecithin-sphingomyelin ratio of amniotic fluid: An antenatal test of lung immaturity?☆

Abstract The total lipid concentration and the lecithin-sphingomyelin ratio (L/S) were measured in the amniotic fluid from human gestations within 24 hours of delivery. The data show that the L/S determined by two-dimensional thin-layer chromatography and the concentration of total lipids are each reliable indicators of gestational age but not of lung immaturity.

The early use of continuous positive airway pressure in the treatment of idiopathic respiratory distress syndrome

Infants with IRDS were treated with CPAP early (0.40 Fi O 2 O 2 ; Pa O 2 O 2 (maximum 0.55) and had a less severe clinical course. The late treated infants were subjected to 0.70 or more Fi O 2 for an average of 24 hours and were in greater than 0.40 Fi O 2 significantly longer than those given CPAP early. Infants who weighed less than 1,500 gm and had severe disease did not do well regardless of when CPAP was applied.

Early versus delayed feeding of low birth weight infants: Effects on physiologic jaundice

Serum bilirubin was higher in low birth weight neonates who were starved for the first 48 hours of life than in groups of those who, beginning at 4 hours of age, were fed water, glucose solution, or hypotonic sodium chloride solution with glucose. No difference in average bilirubin values was demonstrable between the groups of infants fed early. Therefore, neither the intake of salt nor of glucose is essential for the effect. The study suggests that lower serum bilirubin levels result from as little as 23 ml. per kilogram of water daily or from a physiologic process stimulated by feeding regardless of the material ingested. No relationship between blood glucose and bilirubin concentrations was apparent.

Blood volume and blood pressure in infants with respiratory distress

Mean aortic blood pressure volume were measured in true premature infants with respiratory distress syndrome. Seven infants had Type I RDS (hyaline membrane disease) and ten had transient tachypnea of the newborn (Type II RDS). Blood volume in the infants with Type I RDS was significantly lower than in the infants with Type II RDS. The difference was due to a low red cell volume. Mean aortic blood pressure was within the range of normal in all infants and therefore did not reflect the low blood volume of infants with Type I RDS. Normal mean aortic blood pressure does not indicate normal blood volume or normal circulation in infants with RDS.

THE RELATIONSHIP OF FEEDING TO NECROTIZING ENTEROCOLITIS

The records of all newborns with necrotizing enterocolitis (N-E) were reviewed for the years 1968-73. Of the 24 cases, 19 died & N-E was confirmed in all 18 autopsies. The previously reported associations with low birth weight, PROM or amnionitis, asphyxia, & RDS were found. Also, a relationship with feeding was seen—the infants forming 3 groups: Group I-18 infants begun on formula feedings between 4 hrs. to 8 days of life. They developed G.I. signs an average of 31 hrs. later (S.E.=5.6). Formula intake by the 2nd day of feeding averaged 72 cc/kg/day, 133% of the usual daily formula intake in this nursery for infants without overt illness. All 5 who lived (of which none perforated or had surgery) were in this group. Group II-3 infants developed the onset of G.I. signs 15, 20 and 28 days following initiation of feeding, but had other intercurrent problems. Group III-3 infants never fed formula. These had no x-ray or autopsy evidence of pneumatosis. In these 24 patients with N-E, 75% developed the disease related to the onset of feeding. The remainder appeared to develop their disease in relationship to other problems. Formula feeding in this series is very closely associated with the development of N-E, particularly over-aggressive feeding. Feeding is not the sole cause of N-E but is closely enough related to its development to warrant delayed and cautious feeding of infants at risk of N-E.

Intracardiac thrombi complicating central total parenteral nutrition: Resolution without surgery or thrombolysis

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The effects of protein hydrolysate-monosaccharide infusion on low-birth-weight infants

Four neonates who weighed between 940 and 1,200 Gm. at birth were studied for themetabolic effects of the infusion of a solution of 4.5 per cent protein hydrolysate with 13.5 per cent monosaccharide. Infusion for 48 hours resulted in increased serum and urine osmolality, positive potassium balance, negative sodium balance, increased serum urea nitrogen, increased blood glucose and total hexose, and decreased aortic arterial pH. One infant developed Candida albicans sepsis. From these limited data it is concluded that before prolonged parenteral alimentation is applied clinically to the care of low-birth-weight neonates, the relationship of benefit to risk must be evaluated by controlled studies.

A paper chromatoelectrophoresis method for the determination of bilirubin binding to serum protein.

Summary: A technique is described in which paper chromatoelectrophoresis is used to measure the bilirubin binding capacity of albumin in scrum. It is equivalent to the Sephadex G-25 method and its results are highly reproducible. From a single pool of serum, multiple determinations indicated the mean bilirubin binding capacity to be 23.7 ± 0.76 (SD) mg/dl and the greatest difference between any two values was 2 mg/dl. This new technique can determine the bilirubin binding capacity of a serum sample in 15 min. Highly skilled technicians are not needed and very small quantities of serum are required, which gives it a definite advantage over the Sephadex G-25 method.Speculation: Paper chromatoelectrophoresis is a simple, rapid, and inexpensive technique which can be used to measure the bilirubin binding capacity in very small volumes of serum. It appears to have sufficient accuracy and reliability to be applied as a clinical guide to the severity of unconjugated (indirect acting) hyperbilirubinemia in the newborn infant. If further experience with the method supports this report, decisions regarding phototherapy and exchange transfusion to treat infants with unconjugated hyperbilirubinemia might be made on a more rational basis.The technique could be made much more sensitive by using radioactive bilirubin. In this way, it could become a useful research tool in the study of bilirubin metabolism.

A Unique Electrode Catheter for Continuous Monitoring of Arterial Blood Oxygen Tension in Newborn Infants

Arterial blood oxygen tension (paO2) is frequently determined in the intensive care of newborn infants with lung or heart diseases. Knowledge of paO2 in such patients is imperative because elevation above the normal range of 50–110 mm Hg. may cause damage to the retina of prematurely born infants sufficient to result in permanent blindness. At present the most reliable technique for monitoring paO2 is intermittent and requires periodic removal of arterial blood samples through a catheter which has been passed through an umbilical artery into the aorta. Analysis is done by means of a micro blood gas analyzer which requires 0.4 – 0.6 ml. of blood. A method of continuously monitoring paO2 would permit better control of the oxygen enriched breathing environment and eliminate the need for frequent sampling which might dangerously deplete the blood volume of a small infant. Several investigators have recently described indwelling systems for measuring paO2.(1,3,4) The authors have developed a new technique which makes it possible to modify an ordinary umbilical artery catheter for continuously measuring paO2.(5) This is done by means of a Polarographic electrode embedded within the wall of the catheter.