Case reports

Gabriele Scalzo*, Giuseppe Ferlazzo**, Paolo Sciuto**, Massimo Mazzamuto*, Giuseppe Calabrese**, Mario Romeo***, Giuseppe Distefano****

* U. O. Pediatric Cardiac Surgery - A. O. Vittorio Emanuele-Ferrarotto-S. Bambino, Catania
** U. O Anastesia and Resuscitation Operative Unit - Ferrarotto Hospital, Catania
*** UTIN University Polyclinic of Catania
**** U. O Neonatal Diseases Operative Unit and Pediatric Cardiology Division - University Polyclinic of Catania

 INTRODUCTION

The indications for the use of exogenous surfactant have been historically limited to the treatment of respiratory distress in premature neonates. In pediatric heart surgery, due to the peculiarities of certain congenital cardiac diseases and the use of techniques for the performing of surgical operations (e.g. extracorporeal circulation, hypothermia, circulation arrest, etc), the possibility of severe respiratory distress arising is not remote.
The authors describe a case of post-operative severe respiratory distress in which an exogenous surfactant was used as a rescue treatment, in the absence of descriptions in literature of the use of surfactant subsequent to pediatric cardiac surgery.
The experience gained from this clinical case study prompted the authors to start a programme using exogenous surfactant in pediatric cardiac surgery for the purpose of evaluating its efficacy when administered according to methods (e.g. broncholavage) that are beginning to spread throughout clinical practice.

MEDICAL HISTORY NOTES

In March of 2003 a 45-days old infant was urgently transferred to our department from the UTIN (Neonatology and Pediatric Intensive Care Unit) of the University Polyclinic of Catania. The child weighed 3.6 kg, had been diagnosed as suffering from Cor Triatriatum without interatrial communication, with the minimum passage of blood through the left interatrial membrane.
From the pathophysiological point of view, this rare congenital heart disease had caused a serious obstruction to the left inflow leading to low systemic flow rate and pulmonary stasis (pulmonary edema). For this reason, emergency corrective surgery was performed, with the removal of the membrane and redirection of a partial anomalous right pulmonary venous return draining into the superior vena cava (encountered during surgery), with autologous pericardial patch after creation of an interatrial defect.
In order to perform this operation, considering the small dimensions of the superior vena cava and the need also to correct the partial anomalous pulmonary venous return, in addition to extracorporeal circulation (duration113'), profound hypothermia (18°) and circulation arrest (duration 83') were also used.
Considering the poor pre-operative conditions of the infant and the gravity of his hemodynamic picture, he came out of the operating theatre with his sternum electively open, under the effect of massive doses of inotropes (adrenaline, isoproterenol) and nitric oxide (NO 20 ppm). Due to the onset of anuria a few hours after arrival in the Neonatal Intensive Care Unit (N.I.C.U.) peritoneal dialysis was initiated.

The delayed sternal closure was performed on the 3rd day post-surgery and diuresis re-appeared on the 4th day post-surgery.

CLINICAL PICTURE

On the 5^th day post-surgery, despite the marked improvement in the hemodynamic picture, a severe gas exchange alteration took place with PaCO₂55 mmHg, PaO₂45 mmHg, desaturation (80 %), pH 7,28. We changed from Volume-Controlled Ventilation 3 l/min, 60 breaths/min, PEEP 3 cm H20, FiO₂ 80 % with a peak airways pressure of 28, NO 20 ppm to: 4 l/min, 60 breaths/min PEEP 15 cmH₂O, FiO₂ 100 % with peak pressures of 50, NO 40 ppm without obtaining any kind of improvement; similarly, all attempts to bring about hyperinflation recruitment using the ambu bag were in vain. Chest X-rays revealed extremely serious diffuse alveolar edema (figure 1). None of the drugs indicated, including cortisones, antiproteases (gabexate mesylate) and ambroxol succeeded in bringing about an improvement.

At this stage, given the experience gained with respiratory distress in premature neonates, the pediatric heart surgeon suggested the use of exogenous surfactant to the resuscitation team. From group discussions extended to the colleagues of the Neonatal Diseases and Pediatric Cardiology Division of the University Polyclinic of Catania, a clear lack of experience emerged in non-neonatal, non-premature patients; it was therefore decided to use exogenous surfactant only as the ultimate therapeutic resource.

TREATMENT

Considering the lack of experience in literature regarding the use of surfactant in pediatric heart surgery, an endotrachealtreatment with pure Curosurf was prescribed, roughly following the dosage patterns suggested on the technical information sheet (100 mg/kg dose).
Four 360 mg doses of Curosurf were administered every 12 hours for 2 days , and hyperinflation recruitment manoeuvres were performed by means of an ambu bag, before and after administration of the surfactant.
The immediate response after the first administration was striking: PaCO₂ 40%, PaO₂ 75%, O₂ saturation 98%, pH 7,33 enabling a decrease of the FiO₂ to 90% (figure 2).

After 24 hours the hemogas analysis parameters were: PaCO₂ 36%, PaO₂ 77%, saturation 100%, pH 7,37 with FiO₂ 80%, tidal volume 4 l/min, 60 breaths/min, PEEP 8 cmH 2O, peak pressures 38 cmH₂O. The hemogasanalytic improvement remained constant after the administration of the second dose. Peritoneal dialysis was interrupted on the 9^th day post-surgery, and the infant was weaned off the NO on the 20^th day post-surgery, extubated on the 33rd day and discharged from the Neonatal Intensive Care Unit (N.I.C.U.) on the 43rd day post-surgery and from the Hospital on the 58^th day post-surgery. Chest X-rays 28 days after the treatment revealed the disappearance of the severe alveolar alterations (figure 3).

DISCUSSION

The clinical severity and dramatic nature of the above case prompted the authors, after having resorted to all the usual forms of therapy, to seek a treatment that could determine a turning point in the clinical conditions of the patient.
In this case, the empiricism dictated by the lack of experience in Pediatric Heart Surgery clearly emerges observing the administration pattern,which was undoubtedly extremely expensive, compared to the treatment methods currently proposed in literature.
In Pediatric Heart Surgery a large number of factors have an effect on the respiratory distress; apart from the ones that are pathophysiologically correlated to the underlying congenital heart disease itself, it is important also to consider systemic inflammatory response syndromes deriving from the surgical trauma and from the use of extracorporeal circulation, subordinated to the activation of coagulation and to the activation of humoral and cellular mediators of the phlogosis with closely correlated mechanisms. In this particular case, medical substances such as nitric oxide, corticosteroids and gabexate mesylate were used, in addition to a variety of ventilation strategies, but no improvements were achieved. The unequivocal, immediate and favourable response to the treatment with Curosurf convinced the authors that they had found a valid therapeutical approach for the treatment of RDS subsequent to pediatric heart surgery, prompting them to devise a study design aimed at the evaluation of the efficacy of surfactant in patients undergoing pediatric heart surgery, providing for the use of surfactant to be extended also to other circumstances (e.g. pre-and post-surgery atelectasis).

REFERENCES

1. Robertson B. New targets for surfactant replacement therapy: experimental and clinical aspects. Arch Dis Child Fetal Neonatal Ed. 1996 Jul;75(1):F1-3.
2. Luchetti M, Ferrero F, Gallini C, Natale A, Pigna A, Tortorolo L, Marraro G. Multicenter, randomized, controlled study of porcine surfactant in severe respiratory syncytial virus-induced respiratory failure. Pediatr Crit Care Med. 2002 Jul;3(3):261-268.
3. Cochrane CG, Revak SD. Surfactant lavage treatment in a model of respiratory distress syndrome. Chest. 1999 Jul;116(1 Suppl):85S- 86S.
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.

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