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Home , Cyanosis, Hypoventilation

nosis is dependent upon both the arterial oxygen saturation and the Problems in Family Practice total concentration. For example, a newborn with cyanotic congenital heart disease and a severe Evaluation of 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, 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 .’ 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 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 , 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 — 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 , 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 — 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 - ) 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 , , opportunity to pick up oxygen from and periodic suggest­ the alveoli. (Example — heart defect) Clinical Evaluation ing an abnormality of the central 4. Ventilation-Perfusion Inequality The initial decision in evaluating a nervous system. When central cyanosis - Despite normal mechanics of respir­ patient with cyanosis should be is due to inadequate oxygen transport ation, portions of the alveoli are not whether the cyanosis is central or (hematologic disease), the respiratory well ventilated. However, these por­ peripheral. This decision is based upon pattern will be normal reflecting a tions of the lung are adequately the color of the tongue and mucous normal process of ventilation. When perfused with blood. (Example membranes. While the extremities and central cyanosis is due to a cardio­ ) nail beds will be blue in both types of vascular abnormality, the pathogenetic 5. Inadequate Oxygen Transport — cyanosis, the tongue will be blue in mechanism is true right-to-left shunt­ Ventilation and diffusion of oxygen central cyanosis and pink in peripheral ing of blood which bypasses the lungs are normal. Blood flow through the cyanosis. The tongue is a high flow, and prevents normal oxygenation. The lungs is normal. Red blood cells are low resistance organ which extracts infant attempts to compensate by incapable of transporting oxygen from very little oxygen from the blood developing a mild increase in rate and the lungs to the tissues. (Example — perfusing it. For this reason, observing depth of breathing without true congenital ) the color of the tongue may be likened respiratory distress. Finally, when to obtaining a central arterial P02 central cyanosis is caused by pulmo­ Peripheral Cyanosis from the ascending aorta. If the color nary disease, there is an impairment of Peripheral cyanosis is due to in­ of the tongue is pink, the observer diffusion or a ventilation-perfusion

202 THE-JOURNAL OF FAM ILY PRACTICE, VOL. 3, NO. 2, 1976 inequality. The breathing pattern is ance. The diagnosis of congenital Difficulty commonly arises in dis­ one of respiratory distress with methemoglobinemia can be confirmed tinguishing pulmonary from cardio­ dyspnea, intercostal and subcostal re­ by drawing up a few drops of blood vascular cyanosis. Several bedside tractions, grunting and nasal flaring. onto filter paper and exposing it to the observations may be helpful in Those patients with central nervous air. Normal blood should become differentiating the two, including the system and hematologic causes of bright red with exposure to air. If the responses to crying and to inhalation central cyanosis are usually easily patient has methemoglobinemia, the of oxygen. In the infant with pulmo­ distinguished by their clinical appear­ color of the blood will remain dark. nary cyanosis, crying will improve the

Table 2. Flow Sheet for Evaluation of Cyanosis

Clinical ■ CYA N O SIS Observations

(pink) (blue) Color of tongue and m ucous m em branes PERIPHERAL CYANOSIS CENTRAL CYANOSIS

(pink) (blue) X I ''Physiologic" I | Pathologic | | Pathologic|

Warming of extremities 1 1. Vasomotor 1 .Shock instability 2. Sepsis 2. Hypothermia 3. C H F in 3. Local acyanotic CHD obstruction

(bradypnea, apnea) () (respiratory distress) (normal) I l I C.N.S. CARDIACPULMONARY HEMATOLOGIC Respiratory pattern

1. I .C . hemorrhage 1. Congenital 2. Subdural hematoma methemoglobinemia

100% O2 by face mask (arterial PO2 (arterial PO2 with positive pressure unchanged) > 100 mm Hg) for 10 min

CARDIAC I p u l m o n a r y ! 1. HMD 2. Aspiration Arterial blood gases, 3. Atelectasis 4. Pneumonia Hgb, H ct, glucose ORGANIC CHD | PTC SYNDROME| 5. Diaphragmatic hernia 1. Hyperviscosity 2. 3. Neonatal 4. Idiopathic

r I (Increased PA Vascularity) (Decreased PA Vascularity) (Increased PV Vascularity) X-ray pattern of pulmonary vascularity 1. Transposition of the 1. Hypoplastic right heart 1- Hypoplastic left heart great vessels syndrome (pulmonary or syndrome (aortic or ) mitral atresia) 2. Pulmonic stenosis and 2. Total anomalous pulmonary patent foramen ovale venous return 3.

THE JOURNAL OF FAM ILY PRACTICE, VOL. 3, NO. 2, 1976 2 03 process of ventilation, and decreases tions for glucose level should be per­ is being processed, further clinical the cyanosis. Inhalation of oxygen formed in every infant with evidence observations are made. The infant’s may also improve pulmonary cyanosis, of a true right-to-left shunt. respiratory pattern is next evaluated as by providing more oxygen to the Anatomic congenital heart disease part of a brief, but complete physical alveolar-capillary interface. Con­ causing cyanosis in the newborn may examination. The clinical picture and versely, for the infant with cardiac be differentiated on the basis of respiratory pattern may differentiate disease, an improvement in ventilation clinical findings, chest x-ray, and elec­ which organ system is involved. The caused by crying, or an improvement trocardiogram. One way to consider respiratory pattern may be especially in oxygen saturation resulting from cyanotic congenital heart disease in helpful in differentiating those infants inhalation of increased oxygen, will the newborn is to classify cases on the with central nervous system disease or not improve cyanosis since a large basis of increased or decreased hematologic disorders. The most diffi­ portion of blood continues to bypass pulmonary arterial vascularity, or cult differentiation is between primary the lungs, never becoming oxygenated. increased pulmonary venous vascu­ cardiac and pulmonary disorders. The Finally, Shannon et al3 have demon­ larity (Table 2).2 In some cases the response of the infant to crying and to strated that the inhalation of 100 electrocardiogram and clinical findings inhalation of oxygen may be helpful in percent oxygen by face mask with may help to further differentiate the making this diagnosis. If the observer positive end-expiratory pressure for a type of congenital heart disease. remains unsure as to the etiology of ten-minute period will clearly differ­ However, the clinical diagnosis of the cyanosis at this point, the infant entiate pulmonary and cardiac causes individual types of congenital heart should have central arterial blood gases of central cyanosis. When the infant disease is often difficult. In addition, performed before and after breathing has pulmonary disease, the central the differentiation of cyanotic con­ 100 percent oxygen by face mask with arterial P02 will frequently rise 100 genital heart disease from persistence positive pressure for a ten-minute mm Hg or more following this test. of the transitional circulation syn­ period.3 Hemoglobin, hematocrit, and When the infant has cardiac cyanosis, drome may be difficult on a clinical dextrostix determinations may be per­ there will be no significant change in basis. For these reasons, when a true formed on the same blood sample. The central arterial P02 since a large right-to-left shunt is apparent, the arterial P 02 will be especially helpful portion of blood will continue to infant should immediately be referred in differentiating between pulmonary bypass the lungs, never having an to a center with diagnostic facilities and cardiac causes of cyanosis. A opportunity to pick up oxygen. for emergency cardiac catheterization marked increase in arterial P02 sug­ and treatment. gests a pulmonary cause. If the arterial Cardiovascular Cyanosis P02 is unchanged, then it is likely that When the response to breathing 100 a cardiovascular cause of cyanosis is percent oxygen by face mask with Summary of Bedside Approach present. At this point, the chest x-ray positive end-expiratory pressure indi­ The principles discussed above can should be reviewed, and an electro­ cates a true right-to-left shunt, the be utilized to carry out a concise and cardiogram obtained if possible. The infant is likely to have a cardiovascular accurate evaluation of any infant with presence of acidemia, , cause for his cyanosis. Two categories cyanosis. By utilizing a series of hypoglycemia, or polythycemia should must be considered in the differential observations in proper order, the be noted and, if possible, treatment diagnosis: (1) congenital heart disease, entire evaluation and a decision regard­ instituted for these abnormalities or (2) persistence of the transitional ing further evaluation and treatment before transfer to a cardiovascular circulation syndrome.4,5 The latter can be completed within approxi­ center for further evaluation. syndrome is characterized by the early mately 30 minutes (Table 2). When The method of evaluation outlined, onset of striking cyanosis in the called to evaluate an infant with if used in a systematic fashion and absence of anatomic congenital heart cyanosis, the initial observation should with understanding of the basic disease or primary pulmonary disease, be the color of the tongue and mucous physiologic principles involved, will associated with mild to moderate membranes. If the tongue is pink, the consistently result in an accurate cardiomegaly, congestive , infant has peripheral cyanosis. Warm­ diagnosis of the type of cyanosis and and an electrocardiogram which is ing of the lower extremity will help to organ system involved. An appropriate usually normal or demonstrates right determine whether the peripheral cya­ decision may be made quickly and ventricular hypertrophy. The syn­ nosis is “physiologic” or “pathologic.” confidently regarding the need for drome results from persistent pulmo­ If the extremities become pink when further treatment and/or referral. nary vasoconstriction causing abnor­ warmed, then a “physiologic” or References mal right-to-left shunting through the “normal” type of peripheral cyanosis 1. Lees MH: Cyanosis of the newborn ductus arteriosus and foramen ovale. is present and no further evaluation infant. J Pediat 77:484-498, 1970 In most cases the etiology is unknown, 2. Gersony WM: Evaluating cyanosis in needs to be performed. If the extremi­ the newborn. Hosp Pract 4:48-53, 1969 but the syndrome has been associated ties remain blue, then pathologic 3. Shannon DC, Lusser M, Goldblatt A, et al: The cyanotic infant — heart disease or with prenatal or birth asphyxia, causes of peripheral cyanosis should be lung disease. N Engl J Med 28 7:951-953, hypoglycemia, and hyperviscosity carefully investigated. 1 9 7 2 4. Gersony WM: Persistence of the fetal (polythycemia).4 These infants illus­ If the tongue is blue, the infant has circulation: A commentary. J Pediatr trate that the transitional circulation 82:1 103-1106, 1973 central cyanosis which by definition is 5. Nielsen HC, Riemenschneider TA, of the newborn may be adversely pathologic and further evaluation is Ruttenberg HD, et al: Persistence of the affected by metabolic abnormalities. transitional circulation: Sensitivity of the indicated. A portable chest x-ray can newborn cardiovascular system to metabolic Hemoglobin and dextrostix determina­ be obtained at this point and while it stress. J Pediatr, in press

2 0 4 THEJO URN AL OF FAM ILY PRACTICE, VOL. 3, NO. 2, 1976