Résumé
Acute hypoxemic respiratory failure [AHRF] is one of the commonest life-threatening conditions encountered in children. This study was designed to investigate plasma atrial natriuretic peptide [ANP] and endothelin-1 [ET-1] levels in children with AHRF before and after mechanical ventilation [Mv], to clarify their relationship to hemodynamic parameters as well as to assess their prognostic value. Twenty children with AHRF [12 males and 8 females, aged 2 months to 5 years] and ten age-and gender-matched healthy controls were enrolled in this study. Plasma immunoreactive ANP and ET-1 levels were measured just before and one hour after stabilization on MV with pressure controlled ventilation [PCV] and compared with hemodynamic [HR, MBP and CVP] parameters. Blood gas analysis, serum sodium, potassium; urea, creatinine and urine output, sodium and creatinine were measured. Results, Baseline plasma ANP and ET-1 levels were significantly higher in patients than controls, and significantly decreased after stabilization on MV. Early changes of hemodynamics [increased HR and MBP; decreased CVP] and respiratory mechanics [increased MAP; decreased C[DL]] were reversed on MV. Gasometric changes [decreased pH, PaO[2] and PaO[2]/FiO[2], increased PaCO[2] were significantly improved on MV with no effect on PaO[2]/Fio[2] ratio. The initial low serum sodium and potassium levels increased significantly after MV. Mechanical ventilation led to impairment in renal function and reduction in urinary output and sodium excretion. Compared with survivors [n=6], non survivors [n=14] had higher plasma ET-1 and MAP values and lower PaO[2]/FiO[2] ratio. Plasma ANP levels correlated positively with ET-1 levels, MBP, PaCO[2] and negatively with PaO[2]/FiO[2] ratio. Plasma ET-1 levels correlated positively with MAP and negatively with PaO[2]/FiO[2], Plasma ANP and ET-1 levels were markedly increased in children with AHRF and decreased with MV. ET-1 levels will have significant impact on mortality in AHRF. AHRF, acute hypoxemic respiratory failure; ANP, atrial natriuretic peptid ET-1, endothelin4; MV, mechanical ventilation; PCV, positive controlled ventilation; HR, heart rate; MBP, mean arterial blood pressure, CVP, central venous pressure; ABG, arterial blood gases, PaO[2] and PaCQ[2], arterial oxygen and carbon dioxide tensions PaO[2]/FiO[2],ratio of arterial oxygen tension to fraction of inspired oxygen; VT, tidal volume; PEEP, positive end-expiratory pressure; PIP, peak aspiratory pressure; MAP, mean airway pressure; CDL, dynamic lung compliance