nosis is dependent upon both the arterial oxygen saturation and the Problems in Family Practice total hemoglobin concentration. For example, a newborn with cyanotic congenital heart disease and a severe Evaluation of Cyanosis anemia may have an arterial oxygen saturation of only 60 percent, together with a hemoglobin of 6. This infant T * ™ A. Riemenschneider, MD t h e N e W b O m will have 3.6 gnt of oxygenated hemo­ Sacramento, California globin and 2.4 gm of reduced hemo­ The appearance of cyanosis in the newborn may be an indication of globin, and thus by definition will not pathology in the cardiovascular, pulmonary, central nervous, or appear cyanotic, despite the presence of “cyanotic” heart disease. hematologic systems. Peripheral cyanosis (pink tongue, blue extremi­ ties) encountered in the newborn with - vasomotor instability is Types of Cyanosis usually a “physiologic” or normal variant of no significance. When There are two basic types of cyano­ central cyanosis (blue mucous membranes and tongue, blue extremi­ sis — central and peripheral.’ -2 The clinical picture, pathophysiology, and ties) is evident, a pathologic cause of cyanosis is present. Charac­ implications for course and outcome teristic patterns of respiratory effort, response to crying, breathing are considerably different (Table 1). oxygen, and inhalation of 100 percent oxygen by face mask with Central Cyanosis positive pressure may help to differentiate the organ system Central cyanosis is due to a patho­ involved. An approach, founded on basic physiologic principles, is logic process which results in inade­ presented to aid in determining the type of Cyanosis present. By quate oxygenation of central arterial means of a series of simple bedside observations, the clinician can blood.’ It is manifest clinically by the make a rapid, accurate assessment of the cause of the cyanosis in a presence of cyanosis of the tongue and mucous membranes, as well as the particular infant, as well as decisions regarding further diagnostic extremities and nail beds. Beyond the evaluation and treatment. first 20 minutes of life, central cyano­ Cyanosis is a common finding in findings on serial examinations the sis should always be considered abnor­ the newborn nursery. Frequently the physician risks deterioration of the mal. It is caused by pathology in one bluish color in an infant is first noted infant with an organic cause for his of four organ systems: pulmonary, by an observant nurse. The causes of cyanosis. cardiac, central nervous, or hemato­ this discoloration range from benign It would be extremely valuable to logic. The infant with central cyanosis have a practical system which permit­ peripheral vasoconstriction related to will deteriorate, and further evaluation vasomotor instability, to the poten­ ted rapid, reliable assessment of the must be pursued immediately to cause of the cyanosis, based on a few tially fatal “true right-to-left shunt” ensure precise diagnosis and appropri­ easily and rapidly performed clinical associated with cyanotic forms of ate treatment. congenital heart disease. and laboratory observations. Decisions could then be made with confidence In some infants, the physical find­ Peripheral Cyanosis ings, chest x-ray, or electrocardiogram regarding the need for further evalua­ will suggest a specific disease entity or tion and/or referral. The purpose of Peripheral cyanosis is present when organ system involvement. Frequently, this paper is to describe such a system the tongue and mucous membranes are however, a specific diagnosis will not of evaluation, based upon an under­ pink, but the nail beds and extremities be obvious. The physician is then standing of basic physiologic principles are blue. There is normal arterial faced with the choice of “watchful related to the causes of cyanosis. oxygen saturation, but increased ex­ waiting” and frequent reevaluation, or These principles will be discussed traction of oxygen at the tissue level.1 of assuming immediately that the individually and then will be synthe­ Peripheral cyanosis is usually “ physio­ cyanosis may indicate a severe patho­ sized into a scheme for evaluation of logic,” but may occasionally result logic process and alarming the parents, the newborn with cyanosis. from a pathologic process. perhaps needlessly, by arranging for Pathophysiology additional diagnostic studies to obtain Definition In order to have normal oxygena­ a definitive diagnosis. It is a clinical Cyanosis may be defined as a bluish tion of peripheral tissues, the infant axiom that newborns with persistent discoloration of the skin, nail beds, or must have: normal ventilation, normal cyanosis always get worse. Therefore, mucous membranes resulting from the diffusion of oxygen across the by choosing to wait for additional presence of an absolute amount of alveolar-capillary membrane, normal reduced hemoglobin in the blood. transport of oxygen by red blood cells, From the Department of Pediatrics, Univer- Slightly more than 3 gm% of reduced and normal blood flow through the sity of California, School of Medicine, Sacramento Medical Center, Sacramento, hemoglobin must be present in the pulmonary and systemic circulations. California. Requests for reprints should be central arterial blood, or 4 to 6 gm% in Alterations in any of these processes addressed to Dr. Thomas A. Riemen­ schneider, Associate Professor, Cardiovascu­ a sample of “capillary” blood obtained can compromise delivery of oxygen to lar Pediatrics, Sacramento Medical Center, from a finger or heel stick.1'2 The the peripheral tissues and result in a 2315 Stockton Boulevard, Sacramento, Calif 9581 7. presence of clinically detectable cya­ clinical appearance of cyanosis. t h e JOURNAL OF FAM ILY PRACTICE, VOL. 3, NO. 2, 1976 201 may confidently conclude that the Table 1. Characteristics of Central and Peripheral Cyanosis process of oxygenation of the arterial Peripheral Central blood is being accomplished normally. By definition, a patient with a pink Pathophysiology t 02 extraction central arterial at tissue level desaturation tongue has peripheral cyanosis. Con­ versely if the tongue is blue, the Clinical picture pink tongue blue tongue observer can be assured that the arte­ blue nail beds blue nail beds rial P 02 will be decreased and that Arterial O, saturation normal decreased there is some abnormality in the "Physiologic" causes hypothermia — process of oxygenation of the arterial local venous obstruction blood resulting in central cyanosis. vasomotor instability If the infant is determined to have Pathologic causes shock pulm onary peripheral cyanosis (pink tongue), the sepsis cardiovascular next decision should be whether he myocarditis CNS hematologic has a “physiologic” or “pathologic” type of peripheral cyanosis. While this will usually be obvious from physical examination, if there is any question, Central Cyanosis creased extraction of oxygen at the one of the. infant’s lower extremities tissue level. The entire process of There are five basic physiologic may be placed either into a tub of hot oxygenation of the blood is normal mechanisms which cause central arte­ water or wrapped in a hot moist towel and therefore central arterial oxygen rial desaturation and result in central for a five-minute period (test the saturation is normal. Peripheral cyano­ cyanosis. All infants with central temperature yourself to avoid exces­ sis occurs because of one of two cyanosis have one or more of these sive heat). If peripheral cyanosis is due physiologic mechanisms: mechanisms as causes for their to a “physiologic” cause such as cyanosis: 1. Decreased flow of blood through vasomotor instability or hypothermia, the vascular system (Examples — 1. Alveolar Hypoventilation — Indi­ there will be a reflex vasodilatation of shock, sepsis, myocarditis) results in vidual alveoli are not adequately blood vessels in both lower extremi­ ventilated because of shallow, irregular slow flow through capillary beds and ties, and the cyanosis will clear. If respiratory effort. Whatever oxygen increased extraction of oxygen at the cyanosis does not clear with this test, does reach alveoli diffuses normally tissue level. This mechanism should be the infant should be suspected of into pulmonary capillary blood. considered a pathologic cause of having a “pathologic” type of periph­ (Example central nervous system peripheral cyanosis. eral cyanosis. Further investigation disease intracranial hemorrhage) 2. Peripheral vasoconstriction should be made for pathologic causes. 2. Diffusion Impairment — The (Examples — hypothermia, vasomotor If the infant has central cyanosis process of ventilation is normal but instability) results in slow flow (blue tongue), his respiratory pattern oxygen does not diffuse normally through capillary beds and increased should be carefully evaluated. A from alveoli into pulmonary capillary oxygen extraction at the tissue level. characteristic breathing pattern will blood. (Example - pneumonia) This mechanism should be considered frequently suggest pathology in a 3. Right-to-Left Shunt — Ventila­ a “normal” or “physiologic” cause of particular organ system. When the tion and diffusion are normal, but a peripheral cyanosis. It is encountered central cyanosis is due to alveolar portion of peripheral venous blood in many normal newborn infants. hypoventilation the infant will have a bypasses the lungs and joins the sys­ characteristic breathing pattern con­ temic circulation, thus having no sisting of periods of apnea, bradypnea, opportunity to