Neonatology Forum- 3

2 .The optimum oral dose appears to be between I to 1.5 mg per kilo every 4 to 6 hourly.Doses above 2mg per kilo may cause fall in systematic blood pressure leading to deterioration of the pulmonary hypertension.

3. Sildenafil therapy works more effectively when perfusion has been optimized . Hence bolus of saline or plasma 10 to 20 ml per kilo on arrival followed by maximum notropic support appears to be critical for sildenafil to be effective. In addition the optimization of lung volume with high frequency ventilation appears critical to its total effectiveness.

4. The introduction of sildenafil early in the treatment once pulmonary hypertension is diagnosed echocardiographicaly appears to stabilize pulmonary vasculature faster with shorter stay on the ventilator .This so called prophylaxis management rather than rescue appears to be a very important observation in the third index case.

5. The distinct possibility of sildenafil to prevent severe pulmonary hypertension which would require ventilatory support is an important avenue of research. Its a personal observation that in high risk situations, (example, severe birth asphyxia and meconium aspiration) prophylactic use of sildenafil immediately after birth could prevent development of the above mentioned catastrophe. The optimum dose and number of doses have to be determined in further studies as well as optimum blood levels.

6. Sildenafil citrate holds a lot of promise in the treatment of labile pulmonary hypertension of new born and may have limited potential in fixed pulmonary hypertension due to remodeling of pulmonary vasculature. )

Pulmonary hypertension is a potentially fatal lung disorder where the blood vessels supplying the lungs shrink due to noxious stimuli.

As a result , pressure in the arteries of the lungs increases leading to Oxygen deprivation and the patient experiences difficulty in breathing becoming a blue baby. if the ventilator does not bring up the level of oxygen in the blood the next step is to infuse nitric oxide through the ventilator to lower blood vessel resistance in the lungs and improve Oxygenation. If the baby does not respond to nitric oxide the final step may be to use ECMO. Sildenafil may be an alternative option on a compassionate basis. This drug is still under evaluation. How Viagra Works?

Sildenafil enhances the effect of Nitric Oxide (NO ) by inhibiting phosphodiestrase Type 5 which is responsible for the degradation of cyclic GMP in the smooth muscle cells of the pulmonary arterioles .Nitric Oxide is the primary mechanism of dilatation of the / pulmonary arterioles by increasing the levels of cyclic guanosine mono phosphate (GMP) which directly causes smooth muscle relaxation in the arterioles . Hence the blood supply to the lungs improve and the dangerously ill blue baby steadily improves and progresses