UBP 4.7 (Short Form): ENT – UPPP/Obstructive Sleep Apnea

Question 1

What is the significance of his polysomnography study results?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 1

Obstructive sleep apnea (OSA) is suggested by a history of heavy snoring, nocturnal apnea, sleep disruption, and daytime somnolence, but the diagnosis is confirmed by – a sleep study demonstrating five or more events where complete cessation of airflow occurs for at least 10 seconds despite continuing respiratory effort against a closed glottis, and in conjunction with a decrease in arterial oxygenation of > 4%.

The apnea-hypopnea index, consisting of the total number of apneas and hypopneas (50% reduction in airflow for > 10 seconds) per hour, is often used to classify the severity of the disease.

Therefore, this obese patient’s apnea-hypopnea index of 280 indicates severe obstructive sleep apnea/hypopnea syndrome (severe: >30; moderate: 16-30; mild: 5-15), which raises the following anesthetic considerations:

1. the presence of coexisting disease (i.e. hypertension, CAD, cardiac arrhythmias, pulmonary hypertension, right ventricular failure);
2. the choice of anesthetic (regional is preferable, if possible);
3. airway management (difficult intubation is experienced in 13-24% of obese patients with OSAHS),
4. the administration of central nervous system depressants (extreme sensitivity to these drugs may result in airway obstruction and apnea),
5. maintenance of anesthesia (preferred: hydrophilic and short acting drugs),
6. extubation (preferred: fully awake, semi-upright position, full reversal of neuromuscular blockers, intact airway reflexes, and performed in a controlled and monitored environment),
7. post-operative pain control (preferred: NSAIDs, regional analgesia, and minimal short-acting narcotics); and
8. appropriate discharge criteria (ASA practice guidelines recommend monitoring OSA patients for a median of 3 hours longer than non-OSA patients, and for at least 7 hours after the last episode of airway obstruction or hypoxemia.

The adequacy of the patient’s post-operative respiratory function should be evaluated with the patient breathing room air in a non-stimulating environment).

Question 2

What is the differene between obstructive sleep apnea (OSA), obstructive sleep hypopnea syndrome (OSH), obesity-hypoventilation syndrome (OHS), and Pickwickian syndrome?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 2

• OSA is defined as
  
  • a complete cessation of airflow for more than 10 seconds,
  • occurring five or more times per hour of sleep, despite continued respiratory effort against a closed glottis, and
  • associated with a >4% decrease in SpO2.
• OSH represents
  
  • a milder form of the disease,
  • diagnosed when a sleep study demonstrates a 50% reduction in airflow for more than 10 seconds,
  • occurring 15 or more times per hour of sleep, and
  • associated with a >4% decrease in SpO2.
• OHS is a condition that develops secondary to obesity and/or as a long-term consequence of OSA.
  
  • It is defined by the constellation of
    
    • obesity (BMI > 30 kg/m²),
    • daytime arterial hypercapnia (Paco2 > 45 mmHg),
    • nocturnal hypoxia, and
    • polycythemia, in the absence of known causes of hypoventilation (i.e. pulmonary disease).
• Pickwickian syndrome is
  
  • a severe form of OHS in which chronic hypoventilation leads to
    
    • pulmonary hypertension and
    • right ventricular failure.

Question 3

Would you administer anesthesia for this surgery at an outpatient surgery center?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 3

Given this patient’s severe OSA, and the significant risk of postoperative airway obstruction and apnea associated with his condition, I would NOT provide anesthesia for UPPP in an outpatient center.

The ASA practice guidelines for the perioperative management of patients with OSA recommend UPPP and tonsillectomy in children < 3 years old NOT be performed on an outpatient basis.

Factors that I would consider when determining whether outpatient care is appropriate for a patient with OSA include –

• severity of sleep apnea,
• anatomical and physiologic abnormalities,
• coexisting diseases,
• nature of the surgery,
• type of anesthesia being performed,
• need for postoperative opioids,
• adequacy of post-discharge observation, and
• the capabilities of the outpatient center.

Question 4

How would you evaluate this patient’s cardiac status?

Does he need further testing?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 4

Given this patient’s history of obesity, sedentary lifestyle, dyspnea on exertion, uncontrolled hypertension, and OSA,

I would consider him to have significant risk factors for coronary artery disease and congestive heart failure.

I would attempt to illicit further symptoms or cardiac risk factors through –

• a focused history (i.e. unstable and/or severe angina, previous cardiac testing, decompensated heart failure, arrhythmias, myocardial infarction, and functional capacity) and
• physical exam (i.e. jugular venous distension, hepatomegaly, peripheral edema, and pulmonary edema).

If I were unable to adequately assess his cardiac risk, I would consider additional testing, such as –

• a chest radiograph, ECG, ABG, PFTs, and/or an echocardiogram.

A stress echocardiogram, in particular would provide valuable information regarding myocardial ischemia, systolic function, and diastolic filling.

Question 5

What cardiac abnormalities would you expect to find in someone with long-standing obstructive sleep apnea (OSA)?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 5

Chronic arterial hypoxemia and hypercarbia, and an associated increase in serum catecholamine levels, leads to:

1. pulmonary hypertension, secondary to increased sympathetic tone and hypoxic pulmonary vasoconstriction;
2. nocturnal and diurnal systemic hypertension, secondary to increased sympathetic tone;
3. cardiac arrhythmias;
4. polycythemia; and
5. increased platelet aggregability.

Pulmonary hypertension eventually leads to right ventricular hypertrophy and failure (cor pulmonale),

while untreated systemic hypertension leads to left ventricular hypertrophy and failure.

Cardiac arrhythmias may lead to angina, myocardial ischemia, and myocardial infarction in these patients who are already at increased risk of coronary artery disease.

Finally, polycythemia and increased platelet aggregability make these patients more susceptible to thrombotic and embolic cardiac and cerebrovascular events.

Question 6

How would you evaluate this patient’s airway?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 6

I would begin with a history and review of his medical records, looking for information concerning previous intubations, difficulties encountered during airway management, and successful intubation techniques.

Next, I would perform a physical exam focusing on his Mallampati score, nasopharyngeal characteristics, neck circumference, tonsil size, tongue volume, mouth opening, thyromental distance, cervical range of motion, and any anatomical and physiologic abnormalities of the airway.

Moreover, I would consider obtaining cephalometric measurements (radiographs) to evaluate the dental, skeletal, and soft tissue landmarks in the head.

Since OSA is associated with anatomical and physiological characteristics that may predispose patients to difficult airway management, I would ensure the availability of emergency airway equipment and personnel, regardless of the planned intubation technique.

Question 7

The patient is extremely anxious and starting to hyperventilate. The nurse wants to know if she can administer preoperative midazolam. What do you think?

(A 48-year-old obese male is scheduled for elective uvulopalatopharyngoplasty (UPPP). The patient has a history of 12 months progressive weight gain (85 pounds) and excessive daytime somnolence. His wife reports extremely loud snoring at night with agitation and confusion upon waking. He lives a sedentary lifestyle and has significant dypsnea with exertion. Past medical history includes uncontrolled hypertension, hypothyroidism, hiatal hernia, and depression. Medications include HCTZ, lisinopril, synthroid, prevacid, and zoloft. Vital Signs: Weight = 104 kg, height = 172 cm, BP = 165/90 mmHg, HR = 86 bpm. Polysomnography (sleep studies) revealed 280 episodes of apnea or hypopnea lasting greater than 10 seconds, recorded over an eight-hour period of sleep.)

Answer 7

Recognizing that the administration of even small doses of central nervous system depressant drugs places this patient with sleep apnea at risk for airway obstruction, hypoventilation, and/or apnea, my preference would be to avoid administering any preoperative midazolam.

Rather, I would go talk to the patient in order to identify his concerns, answer any questions, and provide the appropriate reassurance.