Left Vocal Cord Paralysis, Lung Function and Exercise Capacity in Young Adults Born Extremely Preterm With a History of Neonatal Patent Ductus Arteriosus Surgery-A National Cohort Study

Abstract

Background: Left vocal cord paralysis (LVCP) is a known complication of patent ductus arteriosus (PDA) surgery in extremely preterm (EP) born neonates; however, consequences of LVCP beyond the first year of life are insufficiently described. Both voice problems and breathing difficulties during physical activity could be expected with an impaired laryngeal inlet. More knowledge may improve the follow-up of EP-born subjects who underwent PDA surgery and prevent confusion between LVCP and other diagnoses. Objectives: Examine the prevalence of LVCP in a nationwide cohort of adults born EP with a history of PDA surgery, and compare symptoms, lung function, and exercise capacity between groups with and without LVCP, and vs. controls born EP and at term. Methods: Adults born EP (<28 weeks' gestation or birth weight <1,000 g) in Norway during 1999-2000 who underwent neonatal PDA surgery and controls born EP and at term were invited to complete questionnaires mapping voice-and respiratory symptoms, and to perform spirometry and maximal treadmill exercise testing. In the PDA-surgery group, exercise tests were performed with a laryngoscope positioned to evaluate laryngeal function. Results: Thirty out of 48 (63%) eligible PDA-surgery subjects were examined at mean (standard deviation) age 19.4 (0.8) years, sixteen (53%) had LVCP. LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, not with lung function or peak oxygen consumption (VO₂peak). In the PDA-surgery group, forced expiratory volume in 1 second z-score (z-FEV₁) was reduced compared to EP-born controls (n = 30) and term-born controls (n = 36); mean (95% confidence interval) z-FEV₁ was -1.8 (-2.3, -1.2), -0.7 (-1.1, -0.3) and -0.3 (-0.5, -0.0), respectively. For VO₂peak, corresponding figures were 37.5 (34.9, 40.2), 38.1 (35.1, 41.1), and 43.6 (41.0, 46.5) ml/kg/min, respectively. Conclusions: LVCP was common in EP-born young adults who had undergone neonatal PDA surgery. Within the PDA-surgery group, LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, however we did not find an association with lung function or exercise capacity. Overall, the PDA-surgery group had reduced lung function compared to EP-born and term-born controls, whereas exercise capacity was similarly reduced for both the PDA-surgery and EP-born control groups when compared to term-born controls.

Keywords: bronchopulmonary dysplasia; cohort studies; exercise test; infant: extremely low birth weight; infant: extremely premature; ligation; patent ductus arteriosus; vocal cord paralysis.

Figure 1

Flow chart of the follow-up study of adults born extremely preterm with a neonatal history of patent ductus arteriosus surgery. CLE, continuous laryngoscopy exercise; CPET, cardiopulmonary exercise test; EP, extremely preterm (gestational age <28 weeks or birth weight <1,000 g); PDA: patent ductus arteriosus.

Figure 2

Comparison of lung function and oxygen consumption between EP adults who underwent neonatal patent ductus arteriosus surgery, EP-born controls, and term-born controls. Error bars of mean with 95% CI for FEV₁ z-score and peak oxygen consumption (ml/kg/min) for the PDA-surgery group, EP-born controls, and term-born controls stratified by gender. Abbreviations: EP: extremely preterm (gestational age <28 weeks and/or birth weight <1,000 g); PDA: patent ductus arteriousus.

Figure 3

Self-reported physical activity among the EP-born participants who underwent neonatal PDA surgery, EP-born controls and term-born controls. Answer to the self-reported question “How many hours per week do you attend sports, exercise, or exert yourself so much that you get out of breath and/or sweat?” Response rate: PDA-surgery: n = 30/30, EP-born controls: n = 25/30, Term-born controls: n = 29/36 p) Chi-square test. EP, extremely preterm (gestational age <28 weeks and/or birth weight <1,000 g); PDA, patent ductus arteriousus.

Figure 4

Laryngeal obstruction during exercise graded by a modified continuous laryngoscopy exercise (CLE) score in the adults born EP with or without left vocal cord paralysis (LVCP). The median CLE-scores are indicated by horizontal lines. p) Mann-Whitney U-test.

Figure 5

Images of the larynx during exercise in EP-born individuals who had undergone neonatal PDA surgery.