Split-Night Protocol*

Transcription

1 Titration for Sleep Apnea Using a Split-Night Protocol* Yoshihiro Yamashiro, MD, and Meir H. Kryger, MD, FCCP We studied 107 patients with sleep-disordered breathing to confirm the effectiveness of continuous positive air way pressure () titration using a split-night proto col. Patients spent two consecutive nights in our labo ratory with complete polysomnography. On the first night, we applied a split-night protocol; the first half of the night was used as a baseline (B), and after a diagnosis was made, was applied during the second half of the night (SN). On the second night (2N), patients spent the entire night on to confirm the effectiveness of treatment. The SN and 2N both revealed a significant reduction in arousal index (37.8 ± 27.9 on B, 13.2 ± 12.1 on SN, 11.4 ± 8.0 on 2N, values are mean ± SD, p), apnea hypopnea index (AHI) (23.6 ± 26.3/h on B, 3.0 ± 3.7/h on SN, 2.4 ± 2.6/h on 2N, p), percent total sleep time below 90% Sa02 (21.0 ±27.2% on B, 8.2 ±13.8% on SN, 4.9 ±10.2% on 2N, p), and percent total sleep time below 80%0 Sa02 (1.1 ± 3.8% on B, % on SN, 0.1 ±0.5% on 2N, p). There were no significant differences between the SN and the Tn most laboratories, patients with sleep apnea are -* evaluated for an entire diagnostic night followed by a continuous positive airway pressure () ti tration night. A single, split-night study for diagno sis and treatment has been reported to be adequate in 78% of patients.1 If confirmed, this type of proto col would be convenient and may be cost-effective. However, this report used data from a single night and selected patients with an apnea hypopnea index (AHI) >20. A recent study by Sanders et al,2 com paring the results of split-night and secondnight, also concluded that determining ade quate pressure can be determined in a single night for most patients with obstructive sleep apnea (OSA).2 The 50 patients evaluated by Sanders et al2 had severe OSA (AHI; 76.7 ±30.6). Therefore we studied 107 consecutive patients with sleep-disor dered breathing (OSA and upper airway resistance syndrome [UARS]3) using a split-night protocol on the night, and compared the results with a second first night with. Materials and Methods Subjects We selected 107 patients who had sleep-disordered breathing *From the Department of Respiratory Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. Manuscript received January 28, 1994; revision accepted June 2. Reprint requests: Dr. Kryger, Sleep Disorders Center, 351 Tache Avenue, Winnipeg, Manitoba R2H 2A6 2N for these measurements. Final pressure was significantly lower at the end of the SN when compared with the 2N (8.8 ±2.7 cm H20 on SN, vs 10.3 ±2.8 cm H20 on 2N, p). When patients were divided into three groups (AHK20, n=69; 20<AHI<40, n=18; AHI>40, n=20), the final pressure was different only in the group with AHK20 (8.1 ± 2.3 cm H20 on SN, 9.6 ±2.3 cm H20 on 2N, p). We conclude that a split-night protocol may be sufficient to determine the effective pressure, especially in patients with an AHI>20. (Chest 1995; 107:62-66) AHI=apnea hypopnea index; Ar-I=arousal index; = continuous positive airway pressure; OSA=obstructive sleep apnea; Sa02=arterial oxygen saturation; SEI=sleep efficiency index; TRT=total recording time; TST=total sleep time; UARS=upper airway resistance syndrome Key words:, sleep apnea syndrome, split-night protocol evaluated in our clinical laboratory. The patients were 90 men and 17 women (aged 52.3 ±12.1 [mean±sd] years; body index, mass 34.4 ±8.2 kg/m2). All of them were referred to our labo ratory because of excessive daytime sleepiness or snoring. Patients were not screened and had not had polysomnography prior to being in this study, and were newly diagnosed as having OSA or UARS. Twenty-three patients who had periodic limb movements in sleep in addition to sleep-disordered breathing were included in the study. None of the patients had other diseases that affect sleep-disordered breathing or sleep quality. All of the patients spent two consecutive nights in our labora tory. On the first night, patients underwent a split-night protocol. Patients were in bed for 7 to 8 h and were instrumented for complete polysomnography. All of the patients had been in structed that might be applied during the night, and had seen a short film explaining. No other instruction or train ing for adaptation to was done. On the split night, after 3 to 4 h of baseline sleep for diagnostic purposes, we applied to the patients for the remainder of the night. The assessment was made by technicians during the study based on breathing abnor malities (apnea and hypopnea), oxygen desaturation, and disor dered breathing-related arousals. Diagnosis was confirmed by physicians analyzing the entire polysomnographic record on the following day. Patients with severe apnea confirmed by repetitive oxygen desaturations below 80% or with cardiac arrhythmias had applied earlier. In some patients, apnea may not have been confirmed until later in the night, and accordingly, was applied later. The pressure was started at 3 cm H2O and was increased gradually by 1 or 2 cm H2O until apneas, hypop neas, and disordered breathing-related arousals were abolished. On the second night, patients were studied on for the en tire night to confirm the effectiveness of treatment. Again, pressure was started at 3 cm H2O and the pressure increased more rapidly than during the split night. When the final pressure of the 62 Titration for Sleep Apnea Using Split-Night Protocol (Yamashiro, Kryger)

2 TRT, min, cm H20 Table I.Results in 107 Patients* 1. Baseline 2. Split-Night ± ± ± ± ± ± ± ± ± ± ±3.8 *Values are mean ± SD. SEI=sleep efficiency index; SI, %=percent of TST in stage 1; S2, =percent of TST in stage REM. split-night study was reached, effectiveness was evaluated and the pressure optimized. We recorded the electroencephalogram (C4/A1, 01/A2), electro-oculogram, and mental electromyogram from surface electrodes. Arterial oxygen saturation (Sa02) was recorded con tinuously with a pulse oximeter (BIOX 3700, Ohmeda, Boulder, Colo) using an ear probe. Respiratory excursions of the chest wall and abdomen were monitored by using respiratory inductive plethysmography (SARA Unit, Vitalog Inc, Redwood, Calif). The electrocardiogram was recorded and heart rate was determined beat by beat using a tachometer. Airflow was detected by mon itoring expired CO2 at the nose and mouth through a nasal cannula attached to a CO2 analyzer (Normocap 200, Datex Medical Instruments, Tewksbury, Mass). The electromyogram of the an terior tibialis was recorded from surface electrodes on both legs. All variables were recorded at a speed of 10 mm/s onto paper using a polygraph (Grass model 78E, Grass Instruments, Quincy, Mass). All respiratory excursions, Sa02, airflow, and heart rate were sampled by a microcomputer system (IBM AT compatible).4 Statistical Analysis Sleep stages were scored manually according to standard cri teria.5 The AHI was calculated by a computer system.6 Arousals were defined as alpha activity or increased EEG frequency last TRT, min, cm H2Q ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±2.8 3>1&2 3>1&2 1&3>2 <0.01 1&2>3 <0.01 3>2 2>3>1 =percent of TST in stage 2; =percent of TST in stages 3 and 4 sleep; Table 2.Results in 69 Patients With AHK20* 1. Baseline 2. Split-Night ± ± ± ± ± ± ± ± ± ± ±1.2 *Values are mean±sd. =not significant. SEI=sleep efficiency index; SI, %=percent of TST in stage 1; S2, =percent of TST in stage REM ± ± ± ± ± ± ± ± ± ± ±2.3 ing for 3 to 15 s. The AHI, total recording time (TRT; minutes), total sleep time (TST; minutes), sleep efficiency index (SEI; %TST/TRT), percentage of each sleep stage, arousal index (Ar-I; number of arousals per hour of sleep), percentage of TST spent below 90% Sa02, and percentage of TST spent below 80% Sa02 were determined for each condition: baseline (until was applied); split-night (after was applied); and second night. Final pressure of (cm H20) at the end of each night was also determined. We also divided the patients into three groups (AHK20 n=69, 20<AHI<40 n=18, AHI>40 n=20) and calculated the same parameters. One-way analysis of variance and Tukey's post hoc comparison were employed for statistical analysis. For the sleep stages we compared the percent of the night of each stage with itself for the three conditions. Results Results in the 107 patients are shown in Table 1. The differences in TRT and TST simply reflect the split-night and second-night protocol. The SEI was significantly lower during the split-night pe riod than during baseline and second-night. There were also significant differences between ± ± ± ± ± ± ± ± ± ± ± ±2.3 <0.01 3>1>2 3>1>2 1&3>2 2>3 1&3>2 2&3>1 =percent of TST in stage 2; =percent of TST in stages 3 and 4 sleep; CHEST /107 /1 / JANUARY,

3 TRT, min, cm H20 Table 3.Results in 18 Patients With 20<AHI<40* 1. Baseline 2. Split-Night ± ± ± ± ± ± ± ± ± ±24.1 L3± ± ± ± ± ± ± ± ± ± ± ±2.8 *Values are mean±sd. =not significant. SEI=sleep efficiency index; SI, %=percent of TST in stage 1; S2, %=percent of TST in stage 2; S34-4, =percent of TST in stage REM. baseline and the split-night, and between baseline and the second night for percent stage 2, percent stage REM, Ar-I, AHI, percent TST below 90% Sa02, and percent TST below 80% Sa02. How ever, there was no significant difference between the split-night and second-night for Ar-I, AHI, percent TST below 90% Sa02, and percent TST below 80% Sa02. Differences between the split-night and second-night were found only in SEI, percent SI, percent S3+4, and the final pressure of. When the patients were divided into three groups (AHK20, 20<AHI<40, AHI>40; Tables 2 through 4), there were significant improvements in Ar-I, AHI, and percent TST below 90% Sa02 during both conditions in all three groups. A significant rebound in REM sleep was also found in all groups. In the group with AHK20, SEI and percent S3+4 were significantly lower during the split-night than during baseline and the second-night, and TRT, min, cm H20 Table 4.Results in 20 Patients With AH1>40* 1. Baseline 2. Split-Night ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±3.6 3>1&2 3>1&2 2>3>1 <0.01 <0.05 =percent of TST in stages 3 and 4 sleep; percent SI during the split-night was lower than during the second-night. Differences in the final pressure were only significant in the patients with AHK20. The distribution of pressure differences in the three groups is shown in Table 5. Eight patients who were changed to bilevel positive airway pressure (ventilatory support system [BiPAP ]) were excluded from the calculation of pressure differences. Figure 1 shows a significant negative correlation between TRT at baseline and AHI in 107 patients (r=. 0.41, p), confirming that patients with more severe apnea were started on a regimen of earlier in the night. When the patients were divided into two subgroups, (1) those with time in the split-night exceeding 3 h, and (2) and those 271.8± ± ± ± ± ± ± ± ± ± ±3.2 with time less than 3 h, the final pres sure difference (A) between the split night and second night was significantly greater in second group (A: mean=1.7±1.7 cm H20 [n=75] vs ± ± ± ± ± ± ± ± ± ± ± ±3.0 3>2>1 3>2>1 2&3>1 *Values are mean±sd. =not significant. SEI=sleep efficiency index; SI, %=percent of TST in stage 1; S2, %=percent of TST in stage 2; =percent of TST in stages 3 and 4 sleep; SREM %=percent of TST in stage REM. 64 Titration for Sleep Apnea Using Split-Night Protocol (Yamashiro, Kryger)

4 Table 5.Distribution of Pressure Differences in Three Groups Pressure Difference, cm H2Q -4 to to 0 7 AHK20 (n=69) to to 4 15 >4 3 Changed to ventilatory 5 support system 20<AHI<40 (n=18) AHI>40 (n=20) 2.7 ± 1.9 cm H20 [n=24], p<0.04). This suggests that if the split-night time is less than 3 h, a greater error would occur in split-night pressure. There was no significant correlation between AHI and pressure difference. Discussion Our results show that there is a significant reduc tion in Ar-I, AHI, percent TST below 90% Sa02, and percent TST below 80% Sa02 during both the splitnight and the second-night compared with baseline; however, there were no significant differences between the split-night and the second-night. These results suggest that a split-night protocol is as effective as a second night in reducing apnea and hypopnea, improving oxygenation, and reducing arousals. The improvements during the split-night are significant even though this time period includes the gradual increase of pressure. This initially slow increase may explain the persistence of percent TST below 90% Sa02=4.9%, and may explain part of the persistently abnormal Ar-I. The Ar-I is also likely to be affected by periodic limb movements in sleep. We did not analyze the period after reaching final pressure on the first night because it was too short to _ 80 X < ^ Baseline TRT r=-0.41 y=-0.16x+62.( p min Figure 1. A significant correlation between baseline total re cording time and apnea hypopnea index. compare with the baseline values of the split-night study. In terms of sleep quality, SEI was lowest during the split-night segment. We believe that this is caused by the procedure to fit a nasal mask, and that patients then had to adapt to and fall asleep again. Rebound was confirmed by a rise in percent stage REM during both the split-night and secondnight conditions, and by an increase in percent stages 3+4 during the second-night. may not have been applied for long enough on the split-night to document percent stages 3+4 increase. In addition, percent stages 3+4 may have been con founded by the propensity for slow-wave sleep in the first third and REM sleep in the last third of the night. However, the large reduction in arousals may indi cate an improvement in sleep quality. Final pressure was significantly higher in the second-night. This difference, however, was small, and when the patients were divided into three groups, significant differences were found only in the group with AHK20. This difference may be due to the relatively small number of patients in the groups with 20<AHI<40, and AHI>40. However, the distribution of final pressure shows that final pressure on the second night was higher than on the split-night in 70% of the group with AHK20 (Table 5). There was a significant correlation between TRT and AHI during the baseline study. This indicates that if patients had a greater AHI, was applied earlier. If the AHI was low, the baseline recording time needed to confirm a diagnosis was longer. There was a significant difference in A pressure between the subgroups (1) time more than 3 h and (2) time less than 3 h on the split night, suggesting that if split-night time was less than 3 h, a greater error might occur in split-night pressure titration. There may not be sufficient time, therefore, to confirm the effectiveness of in patients with AHK20. Since both the technician and the patients knew that there would be another study on the next night, it is possible that the technicians may have waited for the second night for definitive titration in some patients. Most laboratories are using a protocol for patients with sleep apnea that includes an entire diagnostic night followed by a titration night. There is night-to-night variability in apnea7"10 and this vari ability may lead to a false-negative study if patients have a low AHI. In most reports, night-to-night variability in AHI was found mainly in patients with AHK20. We also found significant differences in the final pressure of in patients with AHK20; this may be due to variability in AHI. In patients with AHK20 (including UARS), the diagnosis and sever- CHEST /107 /1 / JANUARY,

5 ity may not be determined correctly in a split-night protocol. Careful follow-up may be necessary to confirm the diagnosis and the effectiveness of treat ment. It has been shown that a split-night protocol was effective in determining final pressure in 78% of patients with OSA.1 In this study, the authors se lected patients with AHI>20, and analyzed data only from a single night. Sanders et al2 studied 50 patients with severe OSA (AHI=76.7±30.6) using protocol a similar to ours, and found that a split-night proto col was effective. The pressure was lower but not statistically significant at the end of the split-night compared with the second night (13 ± 3.5 vs 14 ± 2.9 cm H20). This is similar to our results in groups with 20<AHI<40 and AHI>40. However, their record ing time for baseline, split-night, and the sec ond night was shorter (sleep period time ± 29.3, 132.4±61.9, 257± min) than ours. This time difference may affect the results, because there may not be enough time to reach a true final pres sure. We believe that a split-night protocol was, effective in reducing arousals, apneas, and hypop neas, and improving oxygenation even in patients with AHK20. In three patients, was changed to a ventila tory support system on the second night. Thus, in a small number of patients, a split-night study may result in the patient not being on the appropriate pressure delivery system. Thus, a split-night protocol is effective in reducing AHI and Ar-I, improving oxygenation, and sleep quality in most patients with sleep apnea and UARS. Furthermore, this protocol is convenient and may be cost-effective. Pressure determined using the splitnight protocol may not be adequate in patients with AHK20. Patients with persistent daytime somno lence may need to be reevaluated. Conclusion A split-night protocol may be sufficient to obtain an effective pressure for most patients with obstructive sleep apnea, especially if AHI>20. For patients with AHK20, if symptoms are not improv ing, reevaluation may be necessary to confirm the effectiveness of treatment. References 1 Iber C, O'Brien C, Schluter J, Davis S, Leatherman J, Mahowald M. Single-night studies in obstructive sleep apnea. Sleep 1991; 14: Sanders MH, Kern NB, Costantino JP, Stiller RA, Studnicki K, Coates J, et al. Adequacy of prescribing positive airway pres sure therapy by mask for sleep apnea on the basis of partialnight trial. Am Rev Respir Dis 1993; 147: Guilleminault C, Stoohs R, Clerk A, Cetel M, Maistros P. A cause of excessive daytime sleepiness: the upper airway resis tance syndrome. Chest 1993; 104: West P, Kryger MH. Continuous monitoring of respiratory variables during sleep by microcomputer. Methods Inf Med 1983; 22: Rechtschaffen A, Kales A, eds. A manual of standardized ter minology, techniques and scoring system for sleep stages of human subjects. NIH publication No Bethesda, Md: Na tional Institute of Neurological Disease and Blindness, George CF, Millar TW, Kryger MH. Identification and quan tification of apneas by computer-based analysis of oxygen sat uration. Am Rev Respir Dis 1988; 137: Lord S, Sawyer B, O'Connell D, King M, Pond D, Eyland A, et al. Night-to-night variability of disturbed breathing during sleep in elderly community sample. Sleep 1991; 14: Mosko SS, Dickel MJ, Ashurst J. Night-to-night variability in sleep apnea and sleep-related periodic leg movements in the elderly. Sleep 1988; 11: Aber WR, Block AJ, Hellard DW, Webb WB. Consistency of respiratory measurements from night to night during sleep of elderly men. Chest 1989; 96: Meyer TJ, Eveloff SE, Kline LR, Milkman RP. One negative polysomnogram does not exclude obstructive apnea. Chest 1993; 103: The XXVI Annual National Congress of the Mexican Society of Pulmonology and Thoracic Surgery March 21-24,1995; Zacatecas, Mexico For reservations contact: Intermeeting Travel Agency, Luz Savinon C.P , Mexico City, Mexico. Tel: or ; Fax _ 66 Titration for Sleep Apnea Using Split-Night Protocol (Yamashiro, Kryger)