2017 Sec 1 Green Book

studies have evaluated the effect of LT on persistent OSA in patients with DS. In light of these findings, it was our goal to evaluate the polysomnographic success of LT to resolve persistent pediatric OSA in our patients with DS. MATERIALS AND METHODS Following institutional review board approval at the Cin- cinnati Children’s Hospital Medical Center, we performed a ret- rospective chart review of patients with DS who were age 18 years and younger who underwent LT using radiofrequency ablation 11 from 2003 to 2013. All patients had previously under- gone a T&A and were diagnosed with lingual tonsil hypertrophy using dynamic upper airway cine magnetic resonance imaging (MRI). Patients who completed polysomnography (PSG) before and after LT were included. Patients who did not have both pre- and postoperative PSGs or those whose preoperative obstructive apnea-hypopnea index (oAHI) was < 1 event/hour, were excluded. Charts were reviewed for demographic data and PSG out- comes including the apnea-hypopnea index (AHI), oAHI, O 2 nadir, percent of total sleep time that was rapid eye movement (REM) sleep, percent of sleep study time with CO 2 > 50 mm Hg, obstructive apnea index, hypopnea index, maximum end tidal CO 2 , and central apnea index. PSG Recording PSG was performed with Grass System (Grass Telefactor, West Warwick, RI) for up to 12 hours in a quiet dark room with an ambient temperature of 24 8 C, in the company of their parents. The standard pediatric montage was used. The follow- ing parameters were recorded simultaneously: body position, bilateral electro-occulogram, six-channel electroencephalogram (F3M2, F4M1, C3M2, C4M1, O1M2, O2M1), chin electromyo- gram, anterior tibialis electromyogram, tracheal microphone, electrocardiogram, pulse oximetry (Masimo, Irvine CA), thoracic and abdominal inductance plethysmography, nasal pressure transducer (Pro-Tech, Mukilteo, WA), and end-tidal CO 2 (BCI, Capnochecks; Smiths Medical, St. Paul, MN). Studies were interpreted by board-certified pediatric sleep medicine physi- cians at Cincinnati Children’s Hospital Medical Center. PSG Interpretation All polysomnographs were scored according to the Ameri- can Academy of Sleep Medicine (AASM) guidelines. 12 An apnea was defined as a reduction of airflow of > 90% for at least two breathing cycles. Apneas were identified as obstructive when associated with continued or increased respiratory effort. A mixed apnea was identified when absence of airflow was associ- ated with periods with and without respiratory effort. A hypo- pnea was defined as a decrease in airflow of 50% for at least two breathing cycles followed by a 3% decrease in oxygen sat- uration or an electrocortical arousal from sleep. The obstructive apnea index was calculated as the number of obstructive and mixed apneas divided by the total sleep time. The hypopnea index was calculated as the number of obstructive hypopneas divided by the total sleep time. The AHI was calculated as the number of apneas and hypopneas, divided by the total sleep time. The oAHI was calculated as the sum of the obstructive apneas, mixed apneas, and hypopneas, divided by the total sleep time. Severity of OSA was defined by oAHI. Mild OSA was defined as 1 to < 5 events per hour, moderate OSA was defined as 5 to < 10 events per hour, and severe OSA was

TABLE I. Study Population Demographics for Children With Down Syndrome Who Underwent Lingual Tonsillectomy for Obstructive Sleep Apnea After Adenotonsillectomy.

Demographics, n 5 21

Characteristic

Age at preoperative PSG, yr, mean (SD), median [range] Age at surgery, yr, mean (SD), median [range] Age at postoperative PSG, yr, mean (SD), median [range]

8.9 (4.4), 7.8 [3.6–16.9] 9.3 (4.3), 8.1 [4.4–17.2] 9.7 (4.3), 8.6 [4.6–17.4]

Age at surgery

3–6 years, n (%) > 6 years, n (%) Race, white, n (%) Sex, male, n (%)

7 (33.3%) 14 (66.7%) 19 (90.5%) 11 (52.4%) 82.8 (27.4), 92 [1–99]

BMI percentile, n 5 13, mean (SD), median [range]

Mean and median values are reported. BMI 5 body mass index; PSG 5 polysomnography; SD 5 standard deviation.

defined as 10 events per hour. The saturation nadir was defined as the lowest oxygen saturation reading during a respi- ratory event.

Statistical Analysis Data distributions were reported as means with standard deviations in parentheses and medians with minimum and maximum values in brackets. Due to the fact that the data did not follow a normal distribution, nonparametric statistical anal- yses were conducted to test postsurgery changes. Changes in measurements pre- and postsurgery were tested using the Wil- coxon signed rank test for continuous variables; changes in cat- egorical variables were tested using the McNemar test. RESULTS Forty patients with DS underwent LT, and 21 met the inclusion criteria. The demographics for this study population are displayed in Table I. The mean age at surgery was 9.3 6 4.3 years (47.6% were female and 90.5% were white). Individual patient PSG data can be found in the Supporting Information, Appendix 1A and 1B, in the online version of this article. The median AHI was 9.1 events/hour (range, 3.8 to 43.8 events/hour) before surgery and 3.7 (range, 0.5 to 24.4 events/hour) after surgery (Table II). The median improvement in overall AHI and the oAHI were 5.1 events/hour (range, 2 2.9 to 41 events/hour) and 5.3 events/hour (range, 2 2.9 to 41 events/hour), respectively ( P < .0001). The mean oxygen saturation nadir improved from 84% to 89% ( P 5 .004); however, there were no significant changes in the mean percent time with CO 2 > 50 mm Hg, central index, or percentage of REM sleep. After surgery, the oAHI was < 5 events/hour in 61.9% of patients and 1 event/hour in 19%. After LT, 28.5% of patients had moderate OSA, and 14% had severe OSA, as measured by the oAHI. Stratification of patients by age did not affect the PSG outcomes (Table III). Further

Prosser et al.: PSG Outcomes of Lingual Tonsillectomy in DS

79