2008 Case #1

Case: Ventilator Management 

June 2008
A. Hopper

A 920 gm male infant born to a 22 y.o. G1P0 mother at 26 weeks gestation. Apgars 1/3. The infant presented with tachypnea, retractions and cyanosis. Received blow-by oxygen and placed on nasal CPAP. Electively intubated for surfactant delivery then extubated. Placed on nasal CPAP 5 cm H20 and FiO2 0.50 to keep SpO2 at 90%. An umbilical arterial line was placed and initial ABGs were adequate. CXR demonstrated decreased lung volume and air bronchograms. At 12 hrs, retractions became more severe and infant was dusky and agitated. ABG: 7.18/58/35/21 -8.

What should be done next?

1. Place on nasal IPPV and increase FiO2; repeat ABG in 1 hour
2. Intubate, place on SIMV, increase FiO2, repeat ABG in 1 hour
3. Intubate, place on HFOV, increase FiO2 and repeat ABG in 1 hour

Initial CXR at one hour of age	CXR at 12 hours of age

What is your differential diagnosis?

• Patent ductus arteriosus
• Sepsis
• Intraventricular hemorrhage
• Pulmonary airleak
• Plugged ET tube
• Hypoventilation

Discussion

PDA

• PDA unlikely to contribute to RDS at this early stage of disease
• Ductus is likely to be patent, but PVR is still high so that shunting will be either R→L or bidirectional
• As PVR drops on day 2 or 3, the low will reverse (L→R) causing pulmonary overcirculation and increased respiratory distress

Sepsis

• Sepsis is a possibility
• Hypotension, poor perfusion and large base deficit despite adequate oxygenation would further support a dx of sepsis
• Infants with sepsis/asphyxia often have worse RDS because these factors affect endogenous surfactant production

Intracranial hemorrhage

• Common problem in asphyxiated infants at this gestational age
• Clinical signs of major hemorrhage occur at 36-48 hours and include: hypotension, decreasing hct, full fontanel, hyperglycemia, seizures, coma

Pulmonary Airleak

• Common complication of RDS requiring assisted ventilation
• Bedside transillumination and CXR in this case exclude the possibility
• Remember that breath sounds radiate very well in a small chest and evaluation by stethoscope alone may be misleading
• Recent administration of surfactant dose could lead to plugged ET tube

Hypoventilation (correct answer)

• Most likely dx. Disease has worsened because of increasing atelectasis.
• To correct hypoventilation when using CMV, Paw should be increased.
• Increasing FiO2 alone may temporarily improve oxygenation, but does not improve ventilation.

Mean Airway Pressure

• Average pressure delivered to the airways during a given ventilatory cycle
• Represents the area under the curve
• Raising Paw will improve oxygenation in babies with atelectatic disease
• Incidence of complications increases with increasing Paw 

There is no one method for increasing Paw that works for all neonatal respiratory diseases. While placing the baby on nIPPV and increase FiO2 may help, the baby’s oxygenation is low and it may be more beneficial to intubate and place on SIMV with higher Paw in order to improve oxygenation and ventilation. If an infant required Paw >12, consider use of HFOV.