Best clinical practices for the sleep center adjustment of noninvasive positive pressure ventilation (NPPV) in stable chronic alveolar hypoventilation syndromes.
Noninvasive positive pressure ventilation (NPPV) devices are used during sleep to treat patients with diurnal chronic alveolar hypoventilation (CAH). Bilevel positive airway pressure (BPAP) using a mask interface is the most commonly used method to provide ventilatory support in these patients. BPAP devices deliver separately adjustable inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP). The IPAP and EPAP levels are adjusted to maintain upper airway patency, and the pressure support (PS = IPAP-EPAP) augments ventilation. NPPV devices can be used in the spontaneous mode (the patient cycles the device from EPAP to IPAP), the spontaneous timed (ST) mode (a backup rate is available to deliver IPAP for the set inspiratory time if the patient does not trigger an IPAP/EPAP cycle within a set time window), and the timed (T) mode (inspiratory time and respiratory rate are fxed). During NPPV titration with polysomnography (PSG), the pressure settings, backup rate, and inspiratory time (if applicable) are adjusted to maintain upper airway patency and support ventilation. However, there are no widely available guidelines for the titration of NPPV in the sleep center. A NPPV Titration Task Force of the American Academy of Sleep Medicine reviewed the available literature and developed recommendations based on consensus and published evidence when available. The major recommendations derived by this consensus process are as follows: General Recommendations: 1. The indications, goals of treatment, and side effects of NPPV treatment should be discussed in detail with the patient prior to the NPPV titration study. 2. Careful mask fitting and a period of acclimatization to low pressure prior to the titration should be included as part of the NPPV protocol. 3. NPPV titration with PSG is the recommended method to determine an effective level of nocturnal ventilatory support in patients with CAH. In circumstances in which NPPV treatment is initiated and adjusted empirically in the outpatient setting based on clinical judgment, a PSG should be utilized if possible to confirm that the final NPPV settings are effective or to make adjustments as necessary. 4. NPPV treatment goals should be individualized but typically include prevention of worsening of hypoventilation during sleep, improvement in sleep quality, relief of nocturnal dyspnea, and providing respiratory muscle rest. 5. When OSA coexists with CAH, pressure settings for treatment of OSA may be determined during attended NPPV titration PSG following AASM Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients with Obstructive Sleep Apnea. 6. Attended NPPV titration with PSG is the recommended method to identify optimal treatment pressure settings for patients with the obesity hypoventilation syndrome (OHS), CAH due to restrictive chest wall disease (RTCD), and acquired or central CAH syndromes in whom NPPV treatment is indicated. 7. Attended NPPV titration with PSG allows definitive identification of an adequate level of ventilatory support for patients with neuromuscular disease (NMD) in whom NPPV treatment is planned. Recommendations for NPPV Titration Equipment: 1. The NPPV device used for titration should have the capability of operating in the spontaneous, spontaneous timed, and timed mode. 2. The airflow, tidal volume, leak, and delivered pressure signals from the NPPV device should be monitored and recorded if possible. The airflow signal should be used to detect apnea and hypopnea, while the tidal volume signal and respiratory rate are used to assess ventilation. 3. Transcutaneous or end-tidal PCO2 may be used to adjust NPPV settings if adequately calibrated and ideally validated with arterial blood gas testing. 4. An adequate assortment of masks (nasal, oral, and oronasal) in both adult and pediatric sizes (if children are being titrated), a source of supplemental oxygen, and heated humidification should be available. Recommendations for Limits of IPAP, EPAP, and PS Settings: 1. The recommended minimum starting IPAP and EPAP should be 8 cm H2O and 4 cm H2O, respectively. 2. The recommended maximum IPAP should be 30 cm H2O for patients > or = 12 years and 20 cm H2O for patients < 12 years. 3. The recommended minimum and maximum levels of PS are 4 cm H2O and 20 cm H2O, respectively. 4. The minimum and maximum incremental changes in PS should be 1 and 2 cm H2O, respectively. Recommendations for Adjustment of IPAP, EPAP, and PS: 1. IPAP and/or EPAP should be increased as described in AASM Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients with Obstructive Sleep Apnea until the following obstructive respiratory events are eliminated (no specific order): apneas, hypopneas, respiratory effort-related arousals, and snoring. 2. The pressure support (PS) should be increased every 5 minutes if the tidal volume is low (< 6 to 8 mL/kg) 3. The PS should be increased if the arterial PCO2 remains 10 mm Hg or more above the PCO, goal at the current settings for 10 minutes or more. An acceptable goal for PCO, is a value less than or equal to the awake PCO2. 4. The PS may be increased if respiratory muscle rest has not been achieved by NPPV treatment at the current settings for 10 minutes of more. 5. The PS may be increased if the SpO, remains below 90% for 5 minutes or more and tidal volume is low (< 6 to 8 mL/kg). Recommendations for Use and Adjustment of the Backup Rate/ Respiratory Rate: 1. A backup rate (i.e., ST mode) should be used in all patients with central hypoventilation, those with a significant number of central apneas or an inappropriately low respiratory rate, and those who unreliably trigger IPAP/EPAP cycles due to muscle weakness. 2. The ST mode may be used if adequate ventilation or adequate respiratory muscle rest is not achieved with the maximum (or maximum tolerated) PS in the spontaneous mode. 3. The starting backup rate should be equal to or slightly less than the spontaneous sleeping respiratory rate (minimum of 10 bpm). 4. The backup rate should be increased in 1 to 2 bpm increments every 10 minutes if the desired goal of the backup rate has not been attained. 5. The IPAP time (inspiratory time) should be set based on the respiratory rate to provide an inspiratory time (IPAP time) between 30% and 40% of the cycle time (60/respiratory rate in breaths per minute). 6. If the spontaneous timed mode is not successful at meeting titration goals then the timed mode can be tried. Recommendations Concerning Supplemental Oxygen: 1. Supplemental oxygen may be added in patients with an awake SpO2 < 88% or when the PS and respiratory rate have been optimized but the SpO2 remains < 90% for 5 minutes or more. 2. The minimum starting supplemental oxygen rate should be 1 L/minute and increased in increments of 1 L/minute about every 5 minutes until an adequate SpO2 is attained (> 90%). Recommendations to Improve Patient Comfort and Patient-NPPV Device Synchrony: 1. If the patient awakens and complains that the IPAP and/or EPAP is too high, pressure should be lowered to a level comfortable enough to allow return to sleep. 2. NPPV device parameters (when available) such as pressure relief, rise time, maximum and minimum IPAP durations should be adjusted for patient comfort and to optimize synchrony between the patient and the NPPV device. 3. During the NPPV titration mask refit, adjustment, or change in mask type should be performed whenever any significant unintentional leak is observed or the patient complains of mask discomfort. If mouth leak is present and is causing significant symptoms (e.g., arousals) use of an oronasal mask or chin strap may be tried. Heated humidification should be added if the patient complains of dryness or significant nasal congestion. Recommendations for Follow-Up: 1. Close follow-up after initiation of NPPV by appropriately trained health care providers is indicated to establish effective utilization patterns, remediate side effects, and assess measures of ventilation and oxygenation to determine if adjustment to NPPV is indicated.