Overview

  • Routine pulse oximetry screening recommended for all newborns.
  • Primary goal: Detect unsuspected critical cyanotic congenital heart disease (CCHD).
  • Detects respiratory disorders and primary pulmonary hypertension.
  • Overcomes visual limitations; clinical cyanosis easily missed due to dark skin color, poor lighting, or anemia.
  • Detects milder forms of hypoxia invisible to naked eye.
  • Normal oxygen saturation >98% in infants.
  • Threshold for classifying desaturation <95% in room air.

Target Lesions Detected

CategorySpecific Critical Congenital Heart Lesions
Duct-Dependent Systemic CirculationHypoplastic left heart syndrome (HLHS)
Critical aortic valve stenosis
Severe coarctation of the aorta
Interrupted aortic arch
Duct-Dependent Pulmonary Circulation / Right-Sided LesionsPulmonary atresia with intact ventricular septum (PA/IVS)
Critical pulmonary stenosis
Severe Tetralogy of Fallot (TOF)
Tricuspid atresia
Mixing Lesions / TranspositionD-Transposition of the great arteries (D-TGA) (especially at risk for restrictive atrial septum)
Severe Venous/Valvular LesionsObstructed total anomalous pulmonary venous return (TAPVR)
Congenital mitral and tricuspid valve regurgitation
Neonatal Ebstein anomaly

Screening Protocol

  • Timing: Performed between 24 and 48 hours of life.
  • Executed before discharge in asymptomatic newborns.
  • Measurements required: Pre-ductal (right hand) and post-ductal (either foot).

Pulse Oximetry Screening Algorithm

Result CategoryPulse Oximetry CriteriaClinical Action
Pass$\ge$ 95% in right hand or foot AND $\le$ 3% difference between right hand and footScreen passed; routine care.
Fail (Immediate)< 90% in either right hand or footUrgent echocardiography indicated.
Equivocal90–94% in hand or foot OR > 3% difference between right hand and footRepeat screen once in 1 hour.
Fail (Delayed)90–94% OR > 3% difference after third consecutive screenUrgent echocardiography indicated.
flowchart TD
    A[Perform Pulse Oximetry<br>at 24-48 hours of life] --> B{Initial SpO2 Measurement<br>Right Hand & Either Foot}

    B -->|SpO2 < 90%<br>in RH or Foot| C[FAIL Screen]
    B -->|SpO2 >= 95% in RH/Foot<br>AND Difference <= 3%| D[PASS Screen]
    B -->|SpO2 90-94% in RH/Foot<br>OR Difference > 3%| E[Repeat Screen<br>in 1 Hour]

    E --> F{Second SpO2<br>Measurement}

    F -->|SpO2 < 90%<br>in RH or Foot| C
    F -->|SpO2 >= 95% in RH/Foot<br>AND Difference <= 3%| D
    F -->|SpO2 90-94% in RH/Foot<br>OR Difference > 3%| G[Repeat Screen<br>in 1 Hour]

    G --> H{Third SpO2<br>Measurement}

    H -->|SpO2 < 90%<br>in RH or Foot| C
    H -->|SpO2 >= 95% in RH/Foot<br>AND Difference <= 3%| D
    H -->|SpO2 90-94% in RH/Foot<br>OR Difference > 3%| C

    C --> I[Urgent Clinical Evaluation<br>& Echocardiogram]
    D --> J[Routine Neonatal Care]

Follow-up on Positive Screen

  • Urgent echocardiography required.
  • Careful reexamination of peripheral pulses.
  • Four-extremity blood pressure measurements.
  • Detailed cardiac auscultation.

Diagnostic Interpretation of Saturation Discrepancies

Differential Cyanosis

  • Defined as lower extremity saturation lower than right arm saturation (e.g., right wrist 97%, left foot 72%).
  • Indicates right-to-left shunting across patent ductus arteriosus.
  • Associated lesions: Coarctation of the aorta, interrupted aortic arch, persistent pulmonary hypertension.

Reverse Differential Cyanosis

  • Defined as upper extremity oxygen saturation lower than lower extremity saturation.
  • Seen in d-transposition of the great arteries combined with either coarctation of the aorta or persistent pulmonary hypertension of the newborn.

Technical Limitations

  • Accuracy optimal when blood oxygen saturation remains between 90% and 100%.
  • Accuracy decreases when blood oxygen saturation drops to 80–90%.
  • Devices inaccurate when saturation falls below 40%.