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BL: 24-week Neonate Extreme Prematurity (HFOV)
Published November 27, 2001

William French, MA, RRT & Lori Haag, CRT
Lakeland Community College, Kirtland, OH
www.lakeland.cc.oh.us/index.htm

Contents (click to jump directly to that section, or scroll down to read the case)


INTRODUCTION

BL is a neonate born at 24 weeks gestation to a 33-year-old mother, who had one previous pregnancy but no live births. Eighteen weeks into this pregnancy she experienced a spontaneous premature rupture of the membranes with clear fluid. In the 45 days preceding the delivery, BL's mother was put on antibiotics to prevent and control infections, bed rest and magnesium sulfate to reduce the risk of premature labor, and dexamethasone to accelerate maturation of the fetal lungs and decrease the incidence of neonatal respiratory distress syndrome (RDS).


CASE PRESENTATION

BL was delivered vaginally with a breech presentation. After delivery he was placed in a radiant warmer and resuscitation efforts were begun. He showed no signs of respiratory effort; heart rate was 100 after 30 seconds; and he had central cyanosis. He was intubated with a size 2.5 mm endotracheal tube. Paradoxical chest movement and poor gas exchange were noted with bagging. Apgar scores were: 1 after 1 minute, 4 after 5 minutes, and 5 after 10 minutes. At this point, he was transported to the neonatal intensive care unit and placed on high frequency ventilation. Diagnoses were extreme prematurity, RDS, sepsis, and possible pulmonary hypoplasia.

In the NICU, BL was placed on an oscillator. Initial settings were:

mean Paw
(mean airway pressure)
20 cmH2O flow 20 L/min
delta P
(pressure gradient)
34 cmH2O frequency 12 Hz (720 bpm)
insp. time 33% FiO2 100%

He was given morphine sulfate for sedation.

BL's initial weight was 935 g and his height was 34.5 cm. His general appearance was lethargic with gasping and increased respiratory effort. His initial SpO2 levels were in the 70s and 80s, but eventually climbed into the 90s. His skin showed bruising in the abdominal area with sores on the chest wall and lower extremities. In addition, he had a small chin, deviated nose, and low ears. Initial arterial blood gas results were:

pH 7.11 PaO2 53 mmHg
PaCO2 80 mmHg SaO2 78%
HCO3 26 mEq    

In response, the Paw was increased to 24 and the delta P was increased to 36.

The initial chest radiograph showed good placement of the ET tube and UAC and UVC lines. It also showed developing blebs in all lung fields and a possible pneumomediastinum. In addition, the lungs appeared hyperinflated with blunted costophrenic angles. The apparent development of pulmonary interstitial emphysema (PIE) warranted an immediate response. The settings on the ventilator were changed, decreasing the delta P from 36 to 15 over approximately one and a half hours. This resulted in a progressive decrease in pH from 7.11 to 6.97 and an increase in PaCO2 from 92 to 148. However, the PaO2 increased from 27 to 50 over the same period.

After the last ventilator change, 3.7 mL of Survanta was instilled via the surfactant port adapter of the endotracheal tube. An ABG drawn an hour later showed no improvement. The decision was made to gradually increase the delta P to 28 and decrease the Paw to 15. Ninety minutes later the pH had risen to 7.27 and the PaCO2 had decreased to 69 while the PaO2 held stable. Two hours later, the ABGs showed even greater improvement. In response, the delta P was decreased to 26 and the Paw was decreased to 13.5.

An hour after this, the second dose of Survanta (3.7 mL) was administered via endotracheal tube without complications. ABGs continued to improve. Seven hours later the third and final dose of Survanta was given. A follow up chest radiograph showed much improvement with no evidence of blebs and a resolving pneumomdediastinum. ABGs were:

pH 7.34 PaO2 83 mmHg
PaCO2 58 mmHg SaO2 97%
HCO3 31 mEq    

Three hours later, the decision was made to begin weaning down the oxygen. The FiO2 was decreased from 100% to 50% over a one hour period with good results. Follow up ABGs were good. In response, the delta P was weaned to 23. After this, weaning was continued gradually, and on day three, he was transferred to pressure control ventilation with a PIP of 20, PEEP of 5, flow of 8, Paw 8, rate 30, inspiratory time 46%, and FiO2 40%.

At this point, BL's prognosis is good. The hope is that with proper nutrition, monitoring, and other treatment, he will be successfully weaned from all ventilatory support.


DISCUSSION:

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