Case reports

Luca Tortorolo, G. Polidori
Pediatric Intensive Care Unit, Institute of Pediatrics, Università Cattolica, Rome.

 INTRODUCTION

Over the last few years the introduction of surfactant in the treatment of Neonatal Respiratory Distress Syndrome has radically changed the clinical course of these patients, hugely reducing both mortality and morbidity. In older children, the forms of Acute Respiratory Distress Syndrome (ARDS) share many pathogenic similarities with Neonatal Respiratory Distress Syndrome, notwithstanding the heterogeneous etiology of the conditions: traumas, pneumonia and sepsis [1, 2]. The few studies conducted up to now on efficacy of surfactant treatment in paediatric ARDS have not produced definitive results. Additionally, the methods, doses and type of surfactant that produce efficacious results in children with ARDS are yet to be defined [3, 4, 5, 6, 7].

This clinical case study reports the efficacy, in terms of improved gas exchange and pulmonary mechanics, of surfactant treatment in a patient affected by ARDS secondary to sepsis.

CASE STUDY

The case deals with a four-year-old girl transferred, intubated and artificially ventilated, to the Paediatric Intensive Care Unit of the Gemelli Polyclinic, following post adenotonsillectomy septic shock. In the 48 hours that followed, the patient developed progressive respiratory insufficiency requiring the application of high ventilatory pressures (Map >25 cmH₂O) and high concentrations of O 2 (FiO₂ > 90%). Despite the application of non-aggressive ventilatory criteria allowing blood CO₂ levels of up to 70 mmHg, the oxygenation indices deteriorated progressively: Oxygen Index (O.I.) >30 and O₂ alveolar-arterial difference (AaDO₂) = 560. Moreover, after 72 hours the chest X-ray showed signs of severe ARDS (figure 1) . We then decided to administer a 25 mg/kg instillation of Curosurf^® by endotracheal route distributing it, through manual ventilation with an Ambu bag for 15 seconds, in each of the 4 postural positions (left, right, lying and in the Trendelemburg position). Previously an aliquot of the same surfactant had been used as a bronchoalveolar lavage. Pulmonary mechanics were monitored by means of repeated pulmonary function tests, and all of the cardiorespiratory and ventilator parameters were continuously monitored.

Fifteen minutes after the surfactant instillation, the oxygen requirement gradually dropped, reaching its lowest level (33%) 12 hours later; significant improvements were observed, also relative to the Oxygen Index values (O.I.),alveolar-arterial O₂ difference (AaDO₂) and MAP (mean airway pressure) which decreased to 7 cmH₂O (figure 2).

Pulmonary Compliance and Tidal Volume progressively increased, confirming the clear and rapid improvement in alveolar function (figure 3). Subsequent to this initial stage of improvement, the picture worsened again showing pulmonary compliance values of less than 5 cmH₂O, while the oxygen requirement rose to 65%.

We then proceeded to administer a second dose of surfactant using above-described method, which brought about a further improvement of all of the respiratory function parameters, although the said improvement was not as rapid as that brought about as a result of the first administration. At any event, within a 24-hour period the O. I. dropped to less than 10 and the AaDO₂ to less than 250.

After 3 days, the patient was extubated, breathing spontaneously in an oxygen hood with a FiO₂ of 30% for a further 2 days. When the patient was discharged, pulmonary function tests showed normal pulmonary compliance values (15 cmH₂O).

DISCUSSION

Many experimental trials have demonstrated that the instillation of surfactant can be efficacious in the treatment of ARDS [6, 7, 8, 9]. This severe form of acute respiratory insufficiency has a multifactorial origin, but the common pathogenic event is a considerable reduction in alveolar function, due to the activation of a local inflammatory cascade: inflammation, oedema and extravasation of proteins associated with cardiocirculatory instability increase the consumption of, and inactivate and reduce the production of, endogenous surfactant. This increases susceptibility to alveolar collapse and favours the stagnation of secretions and the development of infective processes, which further worsen the alveolar situation, often generating a spiral of deterioration which is difficult to treat [10, 11, 12, 13].

Our patient’s condition was characterized by the presence of respiratory insufficiency associated with a septic state. Despite the ventilatory treatment carried out by means of permissive ventilation (permissive hypercapnia) [14, 15, 16], the values of the O.I. and the AaDO₂ underwent a rapid deterioration in the days that followed, indicating severe, progressive alveolar damage. Pulmonary function tests (PFT) [17] confirmed the serious alveolar alteration, detecting a very low pulmonary compliance level (4 ml/cmH 2 O). We then proceeded to administer 25 mg/kg of Curosurf^®, a natural surfactant rich in protein components. The protein components of the surfactant, which are fundamental for the antiiflammatory and mechanical functions of the surfactant itself, are the ones most readily consumed in the course of infectious processes.

This clinical case study shows how a surfactantdeficit can play a decisive role in ARDS in a paediatric patient with sepsis and how the pulmonary compliance values can be an excellent parameter for revealing an alveolar dysfunction and for evaluating the patient’s response to the surfactant treatment. Initially, in our patient, the PFTs indicated severe alveolar damage, but after administration of the surfactant they confirmed that a rapid improvement in alveolar function was taking place. Thanks to the beneficial effect of exogenous surfactant in ARDS, mechanical ventilation parameters may be reduced, thereby interrupting the vicious circle which is created when extremely aggressive artificial ventilation parameters become necessary, although these same parameters actually maintain and promote the inflammatory process at alveolar level.

More in-depth clinical trials are called for in order to standardize the doses, methods of administration and types of surfactant to be used in the various forms of ARDS.

A larger study population is of fundamental importance with a view to assessing the impact that surfactant treatment can have on the high mortality rate still generated by this severe respiratory disease.

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