Discussion
Chylothorax is a rare but life-threatening condition in neonates, particularly in neonates with chromosomal abnormalities. It is well known that chylothorax is often seen in children with chromosomal abnormalities, such as trisomy 21, Turner’s syndrome, and Noonan’s syndrome due to vascular and lymphatic malformations2). Conservative treatment using MCT-based formula, octreotide, somatostatin analogues, or corticosteroids has traditionally been performed due to their effect on splanchnic circulation and lipid absorption4). With conservative treatment, complete resolution of pleural fluids can be observed within 30 days for 80% of congenital chylothorax patients5).
However, there are no definite guidelines about which treatment is the most useful for persistent chylothorax. Some authors have suggested that surgical intervention may be necessary in cases with massive or persistent pleural drainage6,7). However, surgery such as pleuroperitoneal shunting, thoracic duct ligation, and lymphaticovenous anastomosis, should be performed only when conservative treatments fail, as such approaches are highly invasive in children. Pharmacologic or chemical pleurodesis has also been suggested as a possible alternative step before surgery in pediatric patients, with instillation of various agents (OK-432, bleomycin, tetracycline, povidone-iodine) in the pleural space8). However, there are no recommendations about which agent is the most useful for managing chylothorax.
OK-432 is an inactivated preparation of Streptococcus pyogenesthat is an effective sclerosing agent9). It causes pleurodesis by inducing a strong cellular and cytokine-mediated inflammatory response and has been widely used to treat macrocystic lymphatic malformations in children10). Although the successful treatment of neonatal and prenatal chylothorax by intrapleural instillation of OK-432 has been reported3,5,7), there are only a few reports in neonates with chylothorax, with reports concerning such patients with chromosomal abnormalities being even rarer. Furthermore, there have been no reports concerning the efficacy of pleurodesis using OK-432 for high-risk patients, such as a low-birth-weight infant with 18 trisomy.
We selected OK-432 because it was allowed for the treatment of chylothorax under the insurance system of our country and had fewer side effects than other agents5). Regarding the dosage, previous reports described the injection of 0.5 KE OK-432 for pleurodesis3). In our case, 1 KE OK-432 (at a concentration of 1 KE in 10 ml normal saline) was injected into the pleural cavity, as substantial chylous effusion was noted, so the concentration of OK-432 might have become diluted. OK-432 was ineffective at the first two sessions due to the shortness of the clamp time because of the patient’s respiratory disorder associated with increasing pleural effusion. Therefore, at the third pleurodesis session, the concentration was changed from 0.1 KE/ml to 0.2 KE/ml, and 1 KE of OK-432 was injected. The chylous effusion gradually decreased due to the increased concentration of OK-432, and chylothorax was ultimately cured after performing pleurodesis five times.
OK-432 is useful for refractory chylothorax, but there are some side effects, including a fever and respiratory disorder5). A fever was observed in the present case after pleurodesis but resolved within a few days. Furthermore, this patient was able to finally be withdrawn from mechanical ventilation at 143 days of life. Now, only oxygenation with a 0.5-L nasal cannula is required at 1 year old, and chest X-ray has shown that the lung field is clear.