Understanding Sleep Apnea Risk for Perioperative Patients

• By Kathryn Hansen
• May 01, 2008

Sleep Apnea & Perioperative Care
Collapse of the upper airway is exacerbated during the perioperative care of a patient, especially if that patient receives general anesthesia and opioid analgesia. Decreased pharyngeal tone reduces ventilation and oxygenation, causing hypoxia and hypercapnia, and inhibits the arousal response associated with each incident of apnea. Also, airway obstructions alter and strain heart and lung function.

Intra-operatively, these patients routinely have more difficult intubations and extubations. They have more potential for adverse events due to hypoxemia, high or low blood pressure, cardiac arrhythmias and aspiration pneumonias seen in the post-anesthesia recovery unit (PACU). Delay in discharge from the PACU is more likely due to the inability to maintain oxygenation at desirable levels for discharge — which results in increased clinical care from nurses, anesthesiologists and respiratory therapists. The risk for cardiopulmonary arrest means these patients often require a discharge from PACU to a higher level of care for more intensive monitoring.

Anesthetics, analgesics and sedative drugs produce increased muscle relaxation of the throat and tongue and may create a blockage of the airway in someone at risk for sleep apnea. When administering anesthetics, the anesthesiologist may need to alter the type and dosage of medication to protect breathing responses. Pain management after surgery also may require an adjustment of doses and pain medication to prevent decreased breathing. As a result, narcotic pain medication or sedation will be balanced to prevent respiratory depression.

Upper abdomen, breast, chest or upper airway surgeries exacerbate complications for at-risk patients because they cause increased breathing discomfort. Respiration is shallow with these surgical procedures, and increased pain adds to discomfort with each breath.

Lying in a supine position during the perioperative period creates added risk because of the relaxation of the muscles in the posterior airway. Unless contraindicated, the head of the bed should be elevated 20-30 degrees to lessen some of the force placed on the posterior airway.

Use of positive air pressure may be required to support breathing after surgery or after a procedure requiring sedation or pain medication, if depressed respirations become a risk.

Impact on Sleep
Sleep is a diverse and complex process that includes two sleep states: NREM (non-rapid eye movement) and REM (rapid eye movement) sleep. Each sleep state performs a different function; both are important to overall daytime effectiveness.

Going to sleep is like descending a stairway. As brain activity slows, we transition into NREM sleep until we reach deep sleep. When in deep sleep, pulse and respiratory slows, blood pressure drops, muscles relax and growth hormone is released to facilitate physical healing, enhanced pain control and physical rejuvenation.Patients at risk for sleep apnea have diminished capacity to maintain adequate time in the deep levels of sleep, reducing the natural capacity to facilitate healing and pain control. If we are sleep-deprived, this process is less efficient and less effective.

About every 90 minutes, we ascend out of deep sleep into REM sleep, an active state of sleep. REM sleep increases breathing, blood pressure, pulse rate and blood flow to the brain. During REM sleep, peripheral muscles are atonic.

REM presents a challenge to sustain breathing, oxygenation and cardiac stability in patients at risk for sleep apnea. All clinical functions become more difficult to sustain. During REM sleep, apneic events are longer, oxygen desaturation is lower and more cardiac arrhythmias are noted. Since the longest REM period occurs in the early morning hours between 4 and 6 a.m., close monitoring of patients during this time is needed to protect them from an adverse event.

Consequences of Untreated Sleep Apnea
Without proactive sleep apnea treatment, perioperative patients and patients receiving drugs that cause sedation have an increased risk for other health complications. The risk for ischemic heart disease is elevated and atrial fibrillation is twice as likely to occur if sleep apnea is untreated.

Sleep deprivation contributes to elevated blood sugar and blood pressure, plus weight gain. Left untreated, elevated insulin contributes to diabetes. With increased weight gain, sleep apnea becomes more severe, contributing to elevated blood pressure.
Patients with sleep apnea are four times as likely to have serious complications, two times as likely to have some post-surgical and post-procedural complications, and have significantly longer hospital stays. A sleep physician should evaluate patients suspected of having sleep apnea. A screening for sleep apnea should be done prior to administering pain medications, sedation or anesthesia.

Medications That Affect Sleep Apnea
Drugs that create respiratory suppression are commonly used in a perioperative and invasive procedural care plan: benzodiazepines for relaxation, narcotics for pain control, antiemetics (Phenergan) for nausea, hypnotics for sleep, and antidepressants for mood or sleep. Close observation and continuous respiratory monitoring is required when substantial analgesia is required, especially when delivered intravenously with a patient-controlled device. IV PCA used with patients at risk for sleep apnea creates increased risk for oversedation by the patient, who has increased need for pain control leading to increased sedation. Increased somnolence from chronic sleep deprivation coupled with drug induced sedation promotes risk for an adverse event. To protect the patient, PAP therapy is required to sustain ventilation while managing pain control.

Anesthesia may cause resedation six to 12 hours after recovery, which creates a risk for an adverse event and requires increased nursing assessment and continuous respiratory monitoring. Excessive daytime sleepiness due to the accumulated sleep deprivation from untreated sleep apnea can exacerbate the situation. When observing a patient for the effects of sedation, it is critical to differentiate between sedation and sleepiness: Does the patient need to be stimulated often to respond to requests? Does the patient fall asleep easily without stimulation?

Increased sedation also increases the patient’s risk for falls, especially later in the night when sedation and sleepiness become more pronounced.

Intervention
With the integration of a dedicated sleep apnea management program and continuous monitoring of oxygenation and ventilation, the possibility of adverse events is reduced. The post-operative or post-procedural management plan should take into consideration the need for close observation by the clinical team and should be combined with the use of PAP when a patient is sedated and asleep. Standing orders used with patients diagnosed or at risk for sleep apnea receiving sedation, pain control and antiemetics provide a standardized treatment plan to reduce the risk of a negative outcome.

The evidence suggests that there is a significant and underappreciated risk for serious injury from sedating agents, opioids and other drugs in the post-procedural or postoperative period. These agents cause life-threatening respiratory depression in patients at risk for sleep apnea. To protect these patients from an adverse event and maintain control of pain, monitoring of ventilation and oxygenation with audible alarms and frequent assessment of vital functions is required. Treatment of sleep apnea with the use of positive air pressure implemented in PACU will protect patients from experiencing an unexpected event.

This article originally appeared in the Respiratory Management May 2008 issue of HME Business.