What is the concerning neck circumference for sleep apnea?

Neck Circumference Thresholds for Sleep Apnea Risk

A neck circumference of ≥17 inches (43 cm) in men and ≥16 inches (40.6 cm) in women is concerning for obstructive sleep apnea (OSA). 1

Clinical Significance of Neck Circumference

Neck circumference is one of the most important physical characteristics that predisposes patients to OSA. According to the American Society of Anesthesiologists (ASA) guidelines, it serves as a key clinical indicator when evaluating patients for potential sleep apnea risk 1.

Risk Stratification by Neck Size:

• Men: ≥17 inches (43 cm)
• Women: ≥16 inches (40.6 cm)
• Commercial vehicle operators: ≥17 inches for men, ≥15.5 inches for women 1

Comprehensive OSA Risk Assessment

Neck circumference should not be evaluated in isolation. The ASA guidelines recommend assessing for OSA risk using three categories of clinical signs and symptoms 1:

1. Predisposing physical characteristics:

   • Increased neck circumference (as noted above)
   • BMI ≥35 kg/m²
   • Craniofacial abnormalities affecting the airway
   • Anatomical nasal obstruction
   • Tonsils nearly touching or touching in the midline

2. History of apparent airway obstruction during sleep (two or more of):

   • Loud snoring (audible through closed door)
   • Frequent snoring
   • Observed breathing pauses during sleep
   • Awakening with choking sensation
   • Frequent arousals from sleep

3. Somnolence (one or more of):

   • Frequent daytime sleepiness/fatigue despite adequate sleep
   • Easily falling asleep in non-stimulating environments
   • For children: appearing sleepy, easily distracted, aggressive, or having difficulty concentrating

Clinical Algorithm for OSA Risk Assessment

1. Measure neck circumference in all patients with sleep complaints or risk factors
2. If neck circumference exceeds thresholds (≥17" men, ≥16" women), consider the patient at increased risk
3. Evaluate for additional risk factors:
   • If signs/symptoms present in two or more categories above, significant probability of OSA exists
   • If any sign/symptom is severely abnormal (markedly increased neck circumference, frightening respiratory pauses), treat as severe OSA risk

Important Considerations and Pitfalls

• Neck circumference is a stronger predictor than general obesity for OSA risk 2, 3
• Gender differences exist: Men typically have larger neck circumferences and higher OSA prevalence than women, even when matched for neck size 4
• Common pitfall: Relying solely on BMI without measuring neck circumference may miss high-risk patients
• Caution: Absence of reported symptoms is less useful than presence of symptoms; patients may be unaware of their sleep-disordered breathing 1

Special Populations

• Commercial vehicle operators: Lower thresholds apply (≥17" men, ≥15.5" women) due to public safety concerns 1
• Bariatric surgery candidates: Particularly high risk with 77% having OSA 1
• Patients with resistant hypertension or type 2 diabetes: Consider OSA evaluation even with borderline neck measurements 1

Neck circumference measurement is a simple, practical clinical tool that should be incorporated into the routine assessment of patients at risk for OSA, as it provides valuable information for risk stratification and helps determine the need for formal sleep studies.