呼吸窘迫症候群(RDS)
呼吸窘迫症候群（RDS）是早產兒常見的問題之一。由於未發展成熟的肺部缺乏肺泡表面張力素，早產兒會出現肺泡擴張不全和肺泡塌陷的情況，導致呼吸困難。嬰兒出生的週數愈早，患上此病的風險就愈高。[1][2]
患有呼吸窘迫症候群的嬰兒在出生後的首數分鐘至幾小時內都可以出現呼吸窘迫的現象。他們的呼吸會較為急促，胸部在呼吸時會有明顯的凹陷，呼氣時發出咕噥聲或有發紺的情況。根據嬰兒出生的週數和病症的嚴重性，他們可能需要不同程度的呼吸支援，例如氧氣治療、非侵襲性正壓呼吸機、插喉和使用機械性輔助呼吸器。
嬰兒出生後，醫生會密切監測嬰兒的維生指數，如血氧飽和度、呼吸頻率和心跳律等。醫生也會透過胸部X光影像來確定呼吸窘迫症候群的診斷，並排除其他可能引起呼吸窘迫的原因。
幸好的是，現時許多產婦如在懷孕34週或之前出現早產的跡象，產科醫生都會為產婦注射皮質類固醇（俗稱「強肺針」）。研究顯示，皮質類固醇可以促進胎兒肺部成熟，從而減低嬰兒患上呼吸窘迫症候群的風險和嚴重程度。[3]
人工表面張力素和呼吸支援是治療呼吸窘迫症候群的主要方法。人工表面張力素是由牛或豬的肺部提取物組成，可用於患有呼吸窘迫症候群的早產兒身上。[4]患者接受人工表面張力素後，肺部的情況一般都會得到改善。大部分患有呼吸窘迫症候群的早產兒亦需要一定程度的呼吸支援，醫生會評估他們的情況，並及時調整治療的方案。
嬰兒體內的肺泡表面張力素會隨著時間慢慢增加，而他們的病情也會隨之而得到改善。有些嬰兒的康復較快，能在短時間內停用所有呼吸支援；但肺部嚴重發育不良的嬰兒可能需要長時間依賴呼吸機。長遠來說，這會增加患上支氣管肺發育不良（BPD）的機會。[5][6]
-撰寫自劉凱盈醫生
威爾斯親王醫院兒科
駐院醫生
Respiratory distress syndrome (RDS)
Respiratory distress syndrome (RDS) is a common problem in preterm babies. It is caused by a lack of pulmonary surfactant in immature lung. The risk increases with decreasing gestational age.[1],[2]
Babies with RDS develop respiratory distress within the first few minutes to hours of life. They may breathe very rapidly, with insucking of the chest, grunting and cyanosis. Depending on their gestational age and the severity of RDS, babies would require different degrees of respiratory support, i.e., free flow oxygen, non-invasive ventilation or intubation and mechanical ventilation.
Babies’ vital signs, like oximetry, respiratory rate and heart rate, are closely monitored after birth. Chest radiographs are taken to look for features of RDS and other possible causes of respiratory distress.
Fortunately, many mothers are now given antenatal corticosteroids before 34 weeks’ gestation if preterm delivery is anticipated. Studies have shown that this reduces the chance and severity of RDS by enhancing fetal lung maturation.[3]
Exogenous surfactant and ventilatory support are the mainstays of treatment in RDS. Exogenous surfactant, an animal-derived substance made up of extracts from the lungs of cows or pigs, is generally recommended for preterm babies with RDS.[4] Improvement in the lung condition is often seen after the baby receives surfactant. It is also common that preterm babies with RDS would require a certain degree of ventilatory support, doctors will assess their condition and make timely adjustments to the treatment provided.
Babies with RDS generally show gradual improvement with time when there is an increase in endogenous surfactant production. While some babies may be successfully weaned off all ventilatory support shortly, babies with less well-developed lungs remain dependent on ventilators for a longer period of time, resulting in a higher chance of bronchopulmonary dysplasia (BPD).[5],[6]
Written by Dr. Sharon Lau
Resident, Department of Paediatrics
Prince of Wales Hospital
Reference:
[1] Stoll BJ, Hansen NI, Bell EF, et al. Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network. Pediatrics 2010; 126:443.
[2] Consortium on Safe Labor, Hibbard JU, Wilkins I, et al. Respiratory morbidity in late preterm births. JAMA 2010; 304:419.
[3] Roberts D, Brown J, Medley N, Dalziel SR. Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. Cochrane Database Syst Rev 2017; 3:CD004454.
[4] Suresh GK, Soll RF. Overview of surfactant replacement trials. J Perinatol 2005; 25 Suppl 2:S40.
[5] Laughon MM, Langer JC, Bose CL, et al. Prediction of bronchopulmonary dysplasia by postnatal age in extremely premature infants. Am J Respir Crit Care Med 2011; 183:1715.
[6] Wai KC, Kohn MA, Ballard RA, et al. Early Cumulative Supplemental Oxygen Predicts Bronchopulmonary Dysplasia in High Risk Extremely Low Gestational Age Newborns. J Pediatr 2016; 177:97.