Cyanosis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sahar Memar Montazerin, M.D.[2] Chandrakala Yannam, MD [3]

Overview

Cyanosis is defined as bluish discoloration of skin and mucous membrane due to decreased oxygenation of tissue. 2% of oxygen is dissolved in plasma and 98% carried by hemoglobin. In central cyanosis, there is decreased oxygen saturation less than 85% or abnormal or nonfunctional hemoglobin whether reduced hemoglobin or desaturated hemoglobin exceeds 5 g/dl. Tongue and conjunctiva become blue and extremities are warm with rapid capillary filling. In peripheral cyanosis, the oxygen saturation is normal but there is inadequate delivery of oxygen or increased oxygen extraction due to peripheral vasoconstriction. Then, extremities are cyanotic, pale, cool but tongue and conjunctiva are pinkish. All causes of central cyanosis can cause peripheral cyanosis. In the presence of anemia and severe hypoxemia, cyanosis may not be apparent due to fewer levels of reduced hemoglobin. Conversely, in polycythemia and mild hypoxemia cyanosis may be easily apparent due to an increased level of reduced hemoglobin.

Causes

Life Threatening Causes

Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.

• Carbon monoxide poisoning
• Cyanide poisoning
• Malathion
• Parathion
• Ethylene glycol
• Epiglottitis
• Foreign body aspiration
• Pulmonary embolism
• Tension pneumothorax
• Hemothorax
• Pulmonary hemorrhage
• Pulmonary hypertension
• Myocardial infarction
• Congestive heart failure
• Disseminated intravascular coagulation
• Tetralogy of fallout
• Cardiac tamponade
• Eisenmenger syndrome
• Anaphylaxis
• Birth asphyxia
• Amniotic fluid embolism

Common Causes

Cyanosis

Central cyanosis

Peripheral cyanosis

Hematologic abnormalities: ❑ Methemoglobinemia (congenital or acquired) ❑ Sulfhemoglobinemia (acquired) ❑ Hemoglobin mutations with low oxygen affinity: ❑ Hb Kansas ❑ Hb Beth israel ❑ Hb Saint Mande ❑ Hb Bruxells ❑ Polycythemia vera ❑ Disseminated intravascular coagulation Metabolic disorders: ❑ Severe hypoglycemia ❑ Inborn errors of metabolism Miscellaneous: ❑ Drugs and chemicals: ❑ Beta blockers ❑ Nitrite or nitrate-containing compounds (eg, nitroglycerin) ❑ Dapsone ❑ Sulfonamides ❑ Benzocaine ❑ Chloroquine ❑ Heroin ❑ Venomous snakebites ❑ Brief resolved unexplained events (BRUE) ❑ High altitude ❑ Congenital diaphragmatic hernia ❑ Cirrhosis of liver ❑ Drowning ❑ Chocking ❑ Hanging ❑ Hypothermia

Hypoventilation:: Upper airway obstruction: ❑ Foreign body aspiration ❑ Pertussis / Croup ❑ Epiglottitis ❑ Bacterial tracheitis ❑ Traumatic disruption (thermal injury, fractures) ❑ Acute chest syndrome ❑ Congenital airway abnormalities: ❑ Choanal atresia ❑ Laryngotracheomalacia ❑ Macroglossia ❑ Micrognathia or retrognathia (eg, Pierre-Robin syndrome) Neurologic abnormalities: ❑ CNS depression ❑ Birth asphyxia ❑ Severe head trauma ❑ Apnea of prematurity ❑ Obstructive sleep apnea ❑ Infections (eg, meningitis, encephalitis) ❑ Intraventricular hemorrhage ❑ Seizures ❑ Cyanotic breath holding spells ❑ Coma Neuromuscular disorders: ❑ Myasthenia gravis ❑ Injury to the phrenic nerve ❑ Type 1 spinal muscular dystrophy (Wernig-Hoffman disease) Intrinsic lung diseases: ❑ Asthma ❑ COPD ❑ Pneumonia ❑ Bronchiolitis ❑ Respiratory distress syndrome (Hyaline membrane disease) ❑ Empyema ❑ Pleural effusion ❑ Cystic fibrosis ❑ Atelectasis ❑ Bronchopulmonary dysplasia ❑ Alveolar capillary dysplasia

Vascular causes: ❑ Cardiac tamponade ❑ Cyanotic congenital heart diseases (Right to left shunts): ❑ Decreased pulmonary flow: ❑ Tetralogy of fallout ❑ Tricuspid valve anomalies: ❑ Tricuspid atresia ❑ Tricuspid stenosis ❑ Ebstein's anomaly ❑ Pulmonary stenosis (critical valvular) ❑ Pulmonary atresia with intact ventricular septum ❑ Increased pulmonary flow: ❑ TGA (Transposition of great arteries, most common dextro type) ❑ Truncus arteriosus ❑ TAPVC (Total anamalous pulmonary venous connection) ❑ Heart failure: Condition that present with cyanosis and severe heart failure include: ❑ Left sided obstructive lesion (HLHS) ❑ Coarctation of aorta ❑ Critical valvular aortic stenosis ❑ Eisenmenger syndrome ❑ Congestive heart failure ❑ Atrial septal defect ❑ Pulmonary hypertension ❑ Pulmonary edema ❑ Pulmonary hemorrhage ❑ Pulmonary embolism ❑ Pulmonary arteriovenous malformations ❑ Multiple small intrapulmonary shunts ❑ Shock ❑ Sepsis ❑ Amniotic fluid embolism

Conditions associated with decreased concentration of inspired oxygen (FiO2): ❑ Smoke inhalation most commonly from house fires ❑ Carbon monoxide poisoning ❑ Hydrogen cyanide poisoning ❑ Intentional or unintensional exposure to asphyxiating gases (eg, Propane, methane, butane, hydrogen sulphide) Impairment of chest wall or lung expansion: ❑ External compression ❑ Pneumothorax ❑ Hemothorax ❑ Flail chest

Causes: ❑ Cold exposure ❑ Acrocyanosis ❑ Erythrocyanosis ❑ Raynaud's phenomenon ❑ Raynaud's disease ❑ Arterial obstruction: ❑ Peripheral vascular disease ❑ Buergers disease ❑ Venous obstruction: ❑ Thromboembolism ❑ Deep vein thrombosis ❑ Superior vena cava syndrome ❑ Decreased cardiac output: ❑ Left sided heart failure ❑ Shock ❑ Hypovolemia ❑ Redistribution of blood flow from extremities

Pseudocyanosis

Metals

Extensive tattoos

Drugs

Pigmentary lesions

Consumption of dyed food

Treatment

Shown below is an algorithm summarizing the treatment of [[disease name]] according the the [...] guideline

TGA, TAPVR ,Truncus arteriosus

Infusion of Prostaglandin, Diuretic therapy

TOF

Hydration, modified blalock taussing shunt, insertion stent in PDA and right ventricular outflow tract, total repair

Treatment of Cyanosis

Ebstein anomaly

Tricuspid valve repair

Hypoplastic left heart syndrome

Infusion of Prostaglandin for keeping patency of ductus arteriosus, infusion of vasodilator for reduced systemic resistance, mechanical ventilation in shock state and imposing hypercapnia and alveolar hypoxia for increased pulmonary resistance

Sepsis, shock, low cardiac output state, cold exposure, metabolic disorder, polycythemia

Treatment of underlying disorder

Eisenmenger syndrome with pulmonary hypertension,

Phosphodiesterase-5 inhibitor (sildenafil, tadalafil, Endothelin receptor antagonist (bosentan,macitentan, ambrisentan)

Methemoglobinemia

Infusion of Methylenblue,dextrose,N-acetyl cystein,cimethidin,ketoconazole

Do's

• Quickly think about hypoplastic left heart syndrome In infants with sudden onset of shock , collapse and severe academia in the first week of life, as well as neonate sepsis and metabolic disorders.
• In ebstein anomaly repair of tricuspid valve indicates if there is :Cyanosis, Right-side heart failure, Poor functional capacity, Paradoxical emboli.
• In differential cyanosis if oxygen saturation of right arm is more than legs and improves with O2 supplemental therapy, think about severe coarctation of aorta, aortic arch interruption, primary pulmonary hypertension.
• In the presence of central cyanosis + hemolytic anemia (jundic,heinze body,fragment RBC)+ renal failure consider about methemoglobinemia.
• Quickly correct dehydration and any distress in infants with cyanotic tet spell in Tetralogy of Fallot to maintain pulmonary blood flow through atretic pulmonary artery and reduced right to left shunt through VSD.
• Think about paradoxical embolism and do a Brain CT scan in cyanotic congenital heart disease because of passing the emboli from right to left shunt and hyperviscosity leading to thrombosis.

Don'ts

• Cyanotic congenital heart diseases that pulmonary congestion is independent on patent ductus arteriosus(PDA) do not worsen with dehydration include :

• Transposition of great arteries(TGA)
• Truncus arteriosus(TA)
• Total anomalous pulmonary venous connection(TAPVR)

References

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