Case reports

Dario Salvo, Giuseppe Pittella, Daniela Buono, Rossella Scappatura

Neonatal and Pediatric Anesthesia and Post-Heart Surgery Resuscitation
S. Vincenzo Hospital, Taormina

INTRODUCTION

The prophylactic and therapeutic use of surfactant in neonatology is now widely accepted in the treatment of respiratory distress associated with lung immaturity.

Cases of neonatal and pediatric respiratory insufficiency not correlated to lung immaturity but successfully treated with exogenous natural surfactant have recently been reported in literature.

The indications for the use of this preparation are therefore being extended to cases of atelectasis with different origins as well as to all those clinical conditions characterized by alterations in the ventilation/perfusion ratio likely to compromise pulmonary compliance.

Recent trials have demonstrated that use of surfactant can be beneficial for treating and/or avoiding pulmonary damage during ECMO ( Extracorporeal Membrane Oxygenation )

This type of damage could be caused by the aggression to which the pulmonary endothelium is subjected, leading to:

• uncontrolled activation of the inflammatory cascade,
• pulmonary microcirculation and hemocoagulative abnormalities,
• consequent perfusion/ventilation mismatching,
• inhibition of endogenous surfactant.

On the basis of the above premise, the administration of exogenous surfactant seems to be indicated during ECMO with a view to safeguarding against pulmonary atelectasis and optimizing the ventilation/perfusion ratio in order to promote alveolar gas exchange. 33

CLINICAL PICTURE

Exogenous natural surfactant ( Curosurf ^® ) was administered during the weaning from ECMO of an infant subjected to an arterial switch operation in deep hyothermia and extracorporeal circulation, since he was affected by congenital transposition of the great arteries and a restrictive VSD.

As a result of the tardy diagnosis (41^st day of life) and the resulting left ventricle insufficiency, weaning from extracorporeal circulation (ECC) was attempted but without success. For this reason, biventricular assistance with ECMO was required for a period of 48 hours. During this period the following parameters were maintained: a flow of 80-100 ml/Kg; an adrenaline intake of 0.05µg/Kg/min; enoximone 7µg/Kg/min; mechanical ventilation maintained in PC: 10 cm H₂O, RR: 16 b/min, FiO₂:40%, PEEP: +4 cmH₂O.

TREATMENT

Surfactant was administered during the phase in which the patient was being weaned from ECMO, immediately after an optimal volume-pressure loop had been obtained. Initially administration was carried out using the broncholavage technique: the surfactant was first diluted with physiological solution at a temperature of 37°C , thereby obtaining 25 mls of solution containing 25mg/ml of surfactant (the dilution recommended for the neonate). Then, five broncholavages were performed within a period of thirty minutes, followed by aspiration of most of the solution introduced.

Through the first broncholavages, the substances likely to inhibit the action of the surfactant were removed.

A small residual volume with the capacity to convey a sufficient quantity of surfactant to enable the drug to exert its stabilizing effect remained inside the lung.

Twelve hours after the last broncholavage, we administered a further dose of 250 mg of pure surfactant .

On suspending the ECMO, immediately before and after administration of the surfactant and up to the 24^th hour, we estimated the PaO₂ (figure 1) through hemogas analysis, keeping the percentage of oxygen inspired constant, and we monitored the peak pressure in the airways (figure 2).

A chest X-ray was performed before and after the treatment.

DISCUSSION

During ECMO, it is of essential importance to ensure scrupulous management of pulmonary ventilation ; this involves maintaining a peak inspiratory pressure of not more than 15/20 cm H₂O, in order to safeguard against barotrauma, and a PEEP high enough to keep the alveoli open.

Despite such precautions, some studies have demonstrated how, 24-48 hours after the commencement of ECMO, chest X-rays reveal pulmonary thickening due to atelectasis.

CONCLUSION

The results of our experience demonstrate stability as regards hemogasanalytic PaO₂ and spirometry measurements after prophylactic administration of surfactant on weaning from ECMO, as borne out by the chest check-up X rays which showed good lung field aeration.

It may, therefore, be concluded that the "prophylactic" administration of surfactant is more efficacious than its "therapeutic" administration , since it takes place when the lung has not yet been seriously damaged and is able to distribute itself in a uniform manner, given the absence, or at any rate, the limited presence, of atelectasic areas.

In conclusion, we can therefore reasonably affirm that, although limited to a single case, our results nonetheless demonstrate alveolar gas exchange stability and a reduction of the atelectasic lung areas after surfactant. A larger study population is, however, required in order to confirm the efficacy of exogenous natural surfactant during ECMO, with a view to standardizing the treatment.

REFERENCES

1. Meister JC, Venkataraman B, Ku T, et al. Lavage administration of dilute recombinant surfactant in acute lung injury in piglets. Pediatr Res 200;47:240-245.
2. Cochrane CG, Revak SD. Surfactant lavage treatment in a model of respiratory distress syndrome. Chest 1999;116:85S-87S.
3. Wayne E, Ricthenbacher MD. Extracorporeal Membrane oxygenation (ECMO) support for cardiorespiratory failure, in "Mechanical Circulatory Support" , 1999 Verlag cap .4 p53-75.
4. Il Surfattante nella Patologia Respiratoria Acuta" Editor Nicola Dirozzi, Daniela Perrotta. Edizione fuori commercio Riservata ai Sigg.Medici SEEd srl in collaborazione con Chiesi Farmaceutici.

Top