Cyanosis is a blue coloration of the skin and mucous membranes due to the presence of greater than, or equal to, 2.5 g/dL of deoxygenated hemoglobin in blood vessels near the skin surface.


A cyanotic baby. Note purple nailbeds.

Cyanosis in the newborn is defined as an arterial saturation less than 90% and a PO2 less than 60 MMHg. A careful history should be obtained from the parents with particular attention to any problems with feeding, breathing, or diaphoresis (sweating). The most common causes include:

  •         Intrinsic pulmonary disease,

  •        Congenital heart disease, 

  •        Central nervous system depression with hypoventilation, 

  •        Blood:

                                    o    Methemoglobinemia,
                                    o    Polycythemia.

  •        Others:               

                                    o    High altitude

                                    o    Hypothermia.

The character of the infant's respirations should be noted. Tachypnea is usually associated with the presence of pulmonary edema and increased pulmonary flow. Auscultation of the lung fields and precordium may reveal rales or murmurs, and abdominal examination may reveal hepatomegaly. Peripheral perfusion, pulses, and coloration should be assessed. Pulse oximetry and an arterial blood gas determinations should be performed immediately if cyanosis is present or suspected.

These measurements should be performed initially on room air to serve as a baseline. Subsequent measurements should be obtained on 100% oxygen and may help to differentiate between cardiogenic and non-cardiogenic causes of neonatal cyanosis. Infants with neurogenic or primary pulmonary causes of cyanosis will demonstrate substantial increases in arterial blood saturation on 100% oxygen while infants with congenital heart disease show minimal elevation. In general, patients with a PO2 greater than 250 mmHg on 100% oxygen will have a non-cardiac problem; conversely, those with PO2 less than 100 mmHg will likely have congenital heart disease.

There are three general sources of arterial desaturation in neonates with structural heart disease:

  1. Lesions with decreased pulmonary blood flow (tetralogy of Fallot, severe pulmonary stenosis/atresia, and tricuspid atresia);
  2. Admixture lesions, in which desaturated systemic venous blood mixes with intracardiac blood, and then enters the aorta (transposition of great vessels, partial anomalous pulmonary venous drainage); and
  3. Lesions with increased pulmonary blood flow and pulmonary edema, in which diffusion barriers and intrapulmonary shunting prevent proper oxygenation (truncus arteriosus).


  • Intrinsic pulmonary disease,
  • Congenital heart disease,
  • Central nervous system depression with hypoventilation,
  • Blood:

·         Methemoglobinemia

·         Polycythemia

·         Others:

·High altitude




Posted on August 20, 2013 - 10:18pm

Content of the Thorax:

  • Mediastinum, 
  • Lungs
  • Chest wall


Posted on August 20, 2013 - 10:50pm

2010 Lectures Tufts University School of Medicine including:


Cardiac defects without a shunt

Posted on November 26, 2010 - 8:56pm

1. Right Heart obstruction

Obstructions can occur at various levels in the right side of the heart or in the pulmonary outflow path. Pure obstructions do not result in a mixing of the blood but cause a massive additional strain on the ventricles because they have to pump against increased resistance.

2. Left Heart obstruction

Introduction to Cardiac congenital defects

Posted on November 26, 2010 - 8:36pm

Congenital cardiac disorders, with an incidence of 1/1000 newborns, belong to the most frequent birth defects. Chromosomal aberrations are frequently associated with heart abnormalities.

Before we go on, please review here the development of the heart:

Cardiac Defects with a Right to Left Shunt (Cyanotic)

In cardiac abnormalities with right-left shunts oxygen-poor blood gets from the right half of the heart into the left side and thus into the systemic circulatory system. In most of the defects with right-left shunts the physiologic shunts present before birth remain functional because no reversal of pressure happens following birth.


Cyanosis is a blue coloration of the skin and mucous membranes due to the presence of greater than, or equal to, 2.5 g/dL of deoxygenated hemoglobin in blood vessels near the skin surface.

Syllabus of Clinical Thoracic and Cardiac Embryologic Problems with anatomic correlations

Posted on August 20, 2013 - 6:07pm

Case studies involving the thorax, mediastinum, embryology of the heart & circulatory systems

Anatomic and clinical reviews that will include basic symptoms and findings, diagnosis & treatment

Tufts University school of Medicine

Clinical Anatomy

Joan F. Tryzelaar, M.D., F.A.C.S, F.A.C.C.P.

 January, 2011

Before we go on to congenital heart problems, it is good to review how to get into the chest:

Clinical Case:

You have just been invited to participate in an operation. The surgeon plans a posterolateral thoracotomy to enter the chest.  He will tell you that he plans entry via the 6th intercostals interspace(Pearl: found two finger widths below the tip of the scapula).