Is there a 'safe mean airways pressure' in preterm babies with hyaline membrane disease: an echocardiographic retrospective approach

Introduction

Airway pressure limitation is a largely accepted strategy in neonatal respiratory distress syndrome (NRDS), yet a lot of debate persists about the exact level of mean airways pressure (M-PAW) that can be safely used. The aim of the present study was to examine whether the echocardiographic evaluation of tricuspid regurgitation (TR) and right ventricular function (RVF) may help to indirectly solve this problem.

Methods

A retrospective study. Thirty preterms were enrolled and divided into two groups: Group A (control group), 15 patients; Group B, 15 patients. Mean gestational age 32 ± 1 weeks, body weight 1.55 ± 0.55 kg, with a diagnosis of NRDS [1]. All of the patients were treated with surfactant therapy (curosurf 100 mg) for grade 3 and grade 4 NRDS and with high-frequency pressure-controlled ventilation: peak pressure according to body weight, PEEP 3 ± 2 cmH₂O, I:E = 1:1.5, breath rate >80 ± 10, FiO₂ 50 ± 15%. In Group B the M-PAWs were reduced according to our echocardiographic evaluations. TR and RVF (pulmonary arterial systolic pressure (PAPs and PAPd), flattening to the left of the interventricular septum) were monitored daily (SONOS 5500-Philips echocardiography machine equipped with 8–12 MHz probes), until beginning weaning from mechanical ventilation.

Results

Signs of right ventricular dysfunction (moderate to severe TR, flattening of interventricular septum, PAPs >36 mmHg) were observed especially in group A with a M-PAW of 14 ± 3 cmH₂O. The duration of mechanical ventilation was 24 hours longer in group A than in Group B (P < 0.005 with the Student t test).

Conclusion

This small experience shows that RVF worsens while increasing the M-PAW over 11 cmH₂O. This event could increase the weaning time in those patients. Even though a large number of patients should be enrolled in our future studies, we believe that any occurrence of right ventricular dysfunction should be immediately corrected, reducing M-PAW with the help of echocardiography.