THE BULLETIN 474 0.XYGE.N AS A SUPPORTIVE THERAPY IN FETAL ANOXIA VIRGINIA: APGAR - Professor of Anesthesiology, Columbia University, College of Physicians and Surgeons HE most secure insurance against fetal anoxia is adequate, spontaneous Trespiration [of the newborn] immediately after birth. The absence of normal ventilation and crying has led to urgent and painstaking efforts to substitute artificial respiration with oxygen by a large variety of methods. It cannot be overemphasized that intermittent pulmonary infla- tion with oxygen at safe pressures is the most effective therapeutic means available in overcoming fetal anoxia. It is the purpose of the present com- munication, however, to examine the role of oxygen in the physiological recovery of the fetus and the therapy of fetal anoxia from the dual aspect of some recent newer knowledge and a critical appraisal of the results of current research. In spite of a steady improvement in neonatal mortality during the past twenty years, there has been almost no decrease in the deaths during the first twenty-four hours after birth.' Is this because we do not under- stand the fundamental causes of death during this period or because we do not apply what is already known? For a variety of reasons, oxygen lack plays the major role in over half the deaths, and the basic treatment for oxygen want is well known. The widespread application of such treatment is sadly lacking. The junior house officer, who is usually left to handle the resuscitative problem, has received instruction only from his immediate superior in the principles of resuscitation, or not at all. It should be the joint responsibility of departments of obstetrics, pedi- atrics and anesthesiology to offer instruction to the internes and residents in all three departments, irrespective of which one takes the initiative for such teaching. Too often emphasis is placed on a certain type of equipment or on certain stimulating drugs while the basic principles of prompt action, the maintenance of a free airway and getting oxygen into the newborn baby are overlooked. Our own specialty has been negligent in exhibiting an interest in this fascinating field and too often obstetrical anesthesia is left to a most inexperienced group. Oxygen in Fetal Anoxin 475 !! f ne anoxia problem has been outlined and discussed nwst clearly and unemotionally by Smith' in Volunle 111 of Advances in Pediatrics. The only practical method of recognizing fetal anoxia before delivery is tllrough the occurrence of a bradycardia. Other comnionly-used diag- nostic signs, such as tachycardia and increase in fetal nioveinents, have not been substantiated experimentally.3 Some Inethod of recording the fetal heart rate continuously in human subjects \vould be a material aid in recognizing fetal anoxia, but so far neither electrocardiographic nor electronic auscultatory Inethods have been successful. Waters and Har- ri%4 Lund5 and BarcroftG have all demonstrated clearly thar the adniini- stration of oxygen to the mother between contractions will correct to a large degree the bradycardia of the fetus during labor pains. This simple mment is not present-day practice in large, busy obstetrical clinics, but should be instituted especially in situations in which neonatal mor- is especially high, Le., prematurity, multiple births and toxemias pregnancy. At the time of delivery, an infant who is apneic, breathes feebly or .@th occasional deep gasps needs oxygen. The presence of cyanosis, pallor, flaccidity and bradycardia merely corroborates this need. The use bf gravity and gentle pharyngeal suction should precede the administra- xion of oxygen. Actual pullnonary inflation can be obtained in countless ways, from the ever-available mouth-to-mouth insufflation to the latest type of mechanical device. Endotracheal suction and inflation are rarely necessary but should be performed quickly and atraumatically by some- one well accustomed to the technique. Obviously, the training program mentioned previously should include practical experience with the tech- $que of these procedures. The damage caused by a period of anoxia at birth has been the sub- jen of many papers. True results are elusive because of the nature of the complications. Psychological maldevelopment is indeed hard to evaluate unless the series is large and the controls are ample. The infants ivho are adequately oxygenated at birth should be followed as assidu- bly as those who are anoxic. Environmental and hereditary consid- erations further complicate interpretation. Objective neurological signs We more accurately interpreted but again a large series of cases is needed. Prolonged studies such as those begun in several cities, notably Wash- inmm and New York, will be enlightening and may produce other Ueqected Signs of damage. It is surprising that no metabolic complica- 476 THE BULLETIN tions have been noted as a result of fetal anoxia. Negative evidence will be as valuable as positive, and reports of the development of a brilliant intellect in spite of anoxia at birth, as in a case cited by Barcroft,' will need elucidation. The remarkable resistance of the fetus to anoxia has been demon- strated in many ways in several species, and the explanation of this fact is nearing completion. In the rabbit, dog and guinea pig the survival time of fetuses of mothers breathing IOO per cent nitrogen was related to the stage of development rather than to the specie^.^ Removal of the medulla is less quickly fatal to newborn small laboratory animals than to the adult.s The pattern of oxygen consumption in various parts of the new- born animal's brain is the opposite of that of the adult, the cortical metabolic rate reversing itself from a low to a high figureg It is probable that some mechanism for anaerobic oxidation exists, for the survival time of fetal animals is not improved under anoxic conditions if the anaerobic use of sugar is withheld. The existence of such a mechanism would help to explain why even more damage does not occur after fetal anoxia, but in no way does its presence excuse negligence in administering oxygen to a newborn infant when the need is clinically indicated. No data at all are available to explain the greater tolerance of the hu;lnm fetus to pre- natal anoxia. The numerous difficulties of embarking upon a study in human beings are obvious. The obstetrical and anesthetic problems are inversely pro- portionate to the skill of the operator. Detailed records of the prenatal problems and an accurately kept chart of the events occurring during delivery call for additional personnel. Simultaneous studies of the mater- nal and fetal blood are desirable. The meticulous technique needed for the study of samples of intact cord blood, well described by Barcroft,6 are not applicable to the usual delivery. A deep heel puncture in the infant supplies a blood sample so closely similar to arterial blood samples that this method has proven practicable. The Roughton-Scholanderl' analysis of the blood sample drawn under oil is relatively reliable. Possibly cor- rection for the type of anesthetic gas in use should be made. The accompanying chart reveals the distribution of oxygen content in volumes per cent, as determined from an initial sampling of blood by the method just described, made within five minutes of delivery of the head in 2 39 consecutive, unselected vaginal deliveries. If ten volumes per cent is the true average figure for the human newborn infant, the causes I Oxygen in Fetal Anoxia 477 vol. % 1-3 cases Sloane Hospital-New, Tork City for our lower mean value 8.0 per cent must be uncovered and corrected. Follow-up studies on these infants in the Pediatric Clinic is planned for a period of five years. SUMMARY The problem of fetal anoxia has been only partially solved in clinical practice. The explanations for the persistence of a relatively higher anoxic mortality in the first day of life are twofold. First, there is the failure to employ adequate methods of artificial ventilation with oxygen promptly after birth. Second, there is still a great deal to learn about the physiology of respiration during and after the birth process. Some infor- mation based upon the oxygen content of newborn blood has been added in this presentation. The importance of the low values observed is not entirely clear at the present time. It is possible that they suggest the presence of effective anaerobic metabolism. 478 THE BULLETIN R E I.' E R E N C E S 1. Dublin, L. and Spiegelman, M. The J. Physwl., 1939, 94:571. Record, Am. Inst. Actuuries, 1941, 7. Glass, H. G., Snyder, F. F. and Web- 30:31. ster, F. The rate of decline in resistance 2. Smith, C. Ll. Effect of birth processes to anoxia of rabbits, dogs, and guinea and obstetric procedures upon the new- pigs from the onset of biability to adult born infant, Advances in Pediatrics, life, Am. J. Physiol., 1944, 140:609. 1948, 3:l. 9. Feldniann, W. M. Principles of ante- 3. Lund, C. J. Recognition and treatment natal and post-natal child physiology, of fetal heart arrhythmias due to anoxia, pure and applied. London, Longmans, Am. J. Obst. Q Qynec., 1940, 40:946. 4. Waters, R. M. and Harris, J. W. Car- 9. Himwich, H. E., Faeekas, J. F. and bon dioxid and oxygen problems in ob- Alexander, F. A. D. Comparative stetric anesthesia, diiesth. 4 Analg., studies of metabolism of brain of in- 1931, 10:59. fant and adult dogs, Proc. Soc. Exper. neonatorum, Am. J. Obst. 4 Qynec., 10. Scholander, 1'. F. and Roughton, F. J. 1941, 41.934. W. Micro gasometric estimation of the 6. Barcroft, tJ , Kramer, K. and Milliken, blood gases, J. Liiol. Chem., 1943, 148: G. O\!gen in carotid blood at birth, 551; 553. Green & Co., 1920. 5. Lund, C. J. Prevention of asphyxia Biol. Q ,Xed., 1941, 46:553.