Dr. Girish jain (1st yr PG) Department :- Respiratory MedicineMahatma Gandhi Medical College and Hospital
ContentsIntroductionMechanismCentral, Peripheral and Differential cyanosis Factors affecting the detection of cyanosisEtiologyPrinciples of Treatment
Introduction Bluish discoloration of the tissues and mucous membrane that results -when the absolute level of reduced hemoglobin (Deoxyhemoglobin) in the capillary bed exceeds 5g/DL.
or increased concentration of abnormal Hemoglobine derivatives (eg. Methemoglobinemia, sulphaemoglobinemia) in the superficial blood vessels.
Mechanism of cyanosisAlveolar hypoventilationDiffusion impairmentVentilation-perfusion mismatchRight-to-left shunting at the intracardiac, great vessel, or intrapulmonary level Hemoglobinopathy (including methemoglobinemia, sulphaemoglobinemia) that limits oxygen transport
central cyanosisPerpheral cyanosisArea generalize localizeTongue involve Not involveHand shake Feel warm Feel coldclubbing Usually present Not presentOn O2 applicationPulmonary cause improved Not improvedApplication of warming Not improved improvedMechanismDiminution of oxygen saturationDiminution of blood flowCapillary refill time 2 sec
Central cyanosisPathologic condition caused by reduced arterial oxygen saturation (SO2).Involves highly vascularized tissues, such as the lips, tongue and mucous membranes, through which blood flow is brisk and the arteriovenous difference is minimal. Cardiac output typically is normal, and patients have warm extremities.
Peripheral cyanosisNormal systemic arterial oxygen saturation and increased oxygen extraction from peripheral blood, resulting in a wide systemic arteriovenous oxygen difference
The increased extraction of oxygen results from sluggish movement of blood through the capillary circulation. Affects the distal extremities, and circumoral or periorbital areas .
Differential cyanosisWhen cyanosis is present only in the toes but not in the fingers, it is called Differential cyanosis. It is seen in PDA.
Pulmonary causes1. Alveolar hypoventilation Central nervous system depression: asphyxia, maternal sedation, intraventricular hemorrhage, seizure, meningitis, encephalitis B. Neuromuscular disease: myasthenia gravis, phrenic nerve injury C. Airway obstruction: choanal atresia, laryngotracheomalacia, macroglossia,
2. Ventilation/perfusion mismatch Airway disease: pneumonia, aspiration, cystic adenomatoid malformation, diaphragmatic hernia, pulmonary hypoplasia, lobar emphysema, atelectasis, pulmonary hemorrhage, hyaline membrane disease, transient tachypnea of the newborn B. Extrinsic compression of lungs: pneumothorax, pleural effusion, chylothorax, hemothorax, thoracic dystrophy
3. Diffusion impairment A. Pulmonary edema: left-sided obstructive cardiac disease, cardiomyopathy B. Pulmonary fibrosis C. Congenital lymphangiectasia
*Methemoglobinemia- An oxidized form of hemoglobin, cannot carry oxygen and, when present in significant quantities, will cause cyanosis. Acquired or congenital disorder due to nicotinamide adenine dinucleotide (NADH) cytochrome b5 reductase deficiency and hemoglobin M disorder.
Cardiac causes1. Decreased pulmonary blood flow-A. Tetralogy of FallotB. Tricuspid valve anomalyC. Pulmonary valve atresiaD. Critical valvular pulmonary steanosis2. Increased pulmonary blood flow-A. Transposition of great arteriesB. Truncus arteriosusC. Total anomalous pulmonary venous connection
3. Severe heart failure-A. Hypoplastic left heart syndromeB. Coarctation of the aortaC. Interrupted aortic archD. Critical valvular aortic steanosis
Hemoglobinopathy : . Methemoglobinemia: congenital or secondary to toxic exposure >1.5gm/dl
.sulphaemoglobinemia: secondary to toxic exposure >0.5gm/dl.
Factors affecting the detection of cyanosis1. Hemoglobin concentration-Detected at higher levels of saturation in polycythemic than in anemic patients.
Significant oxygen desaturation can be present in an anemic patient without clinically detectable cyanosis.
2. Fetal hemoglobin. Binds oxygen more avidly than adult hemoglobin. . The oxygen dissociation curve is shifted to the left, so that for a given level of oxygen tension (PO2), the oxygen saturation (SO2) is higher in the newborn than older infants or adults. It explains that for a given level of oxygen saturation(SO2), the PO2 is lower in newborns. . As a result, cyanosis is detected at a lower PO2 in newborns compared with older patients.
3. Skin pigmentation-. Less apparent in the skin of patients with darker pigmentation. . Examination should include the nail beds, tongue, and mucous membranes, which are less affected by pigmentation.
InvestigationHematocrit or hemoglobinSepsis screeningBlood glucose concentrationArterial blood gases (Pao2, Paco2, pH)Blood culturesElectrocardiographyEchocardiography, cardiac catheterisation, angiocardiographyHemoglobin electrophoresis- Hb M
Treatment of cyanosisIt is a symptom of an underlying condition rather than being a disease in itself. Treatment of cyanosis thus focus on the Treatment of underlying disease rather than the symptom alone.Symptomatic treatment of cyanosis -
1. Warming of the affected areas- Peripheral cyanosis brought about by exposure to cold or Raynauds phenomenon and acrocyanosis may be treated symptomatically using gentle warming of the fingers and toes.
2. Oxygenation as a treatment for cyanosis-Initial stabilization requires oxygenation. Sometimes a breathing machine or ventilator might be required.
3.Intravenous fluids- Children who have difficulty in feeding due to cyanosis and heart failure due to an underlying cyanotic heart disease need to be administered intravenous fluids.
*Methemoglobinemia- An oxidized form of hemoglobin, cannot carry oxygen and, when present in significant quantities, will cause cyanosis. Acquired or congenital disorder due to nicotinamide adenine dinucleotide (NADH) cytochrome b5 reductase deficiency and hemoglobin M disorder. *