What is a safe blood alcohol concentration (BAC) level for patient discharge?

Safe Blood Alcohol Concentration (BAC) for Patient Discharge

Patients should not be discharged from medical care until their blood alcohol concentration (BAC) is below 0.08% (80 mg/dL), with clinical sobriety being the primary determinant for safe discharge.

Understanding Blood Alcohol Concentration and Discharge Safety

Blood alcohol concentration is a critical factor in determining when it's safe to discharge a patient who presented with alcohol intoxication. The decision to discharge should be based on both objective measurements and clinical assessment.

Safe BAC Discharge Thresholds

While there is no universally established guideline specifically addressing discharge BAC levels, several considerations inform safe practice:

• Legal driving limit: Most jurisdictions set 0.08% (80 mg/dL) as the legal limit for driving
• Clinical sobriety: The patient should demonstrate clinical sobriety regardless of numerical BAC
• Risk mitigation: Patients discharged with BAC >50 mg/dL may face legal issues if involved in incidents after discharge 1

Clinical Assessment Algorithm for Discharge

1. Measure initial BAC on admission

   • Document time of measurement
   • Establish baseline for monitoring

2. Calculate estimated time to safe BAC

   • Average alcohol elimination rate: 15 mg/dL per hour 1
   • Formula: Hours needed = (Initial BAC - Target BAC of 0.08%) ÷ 0.015%/hour

3. Clinical assessment before discharge

   • Mental status: Alert and oriented to person, place, time
   • Gait: Stable without assistance
   • Speech: Clear and coherent
   • Judgment: Appropriate decision-making capacity

4. Consider repeat BAC measurement

   • If clinical assessment doesn't match expected BAC based on elimination time
   • If patient has comorbidities affecting alcohol metabolism
   • If initial BAC was extremely high (>300 mg/dL)

Special Considerations

High-Risk Populations

• Patients with traumatic brain injury: Alcohol can mask neurological symptoms; consider longer observation and lower discharge BAC 2
• Patients with liver disease: Impaired alcohol metabolism requires longer observation periods
• Elderly patients: May have increased sensitivity to alcohol effects at lower BAC

Discharge Planning

• Ensure safe transportation home (not self-driving)
• Consider social support at discharge destination
• Provide resources for alcohol use disorder treatment when appropriate

Common Pitfalls in Discharge Decision-Making

1. Relying solely on clinical appearance: Some individuals may appear clinically sober despite elevated BAC due to tolerance 3

2. Failing to document discharge BAC: This creates medicolegal vulnerability if the patient is involved in an incident after discharge

3. Discharging based on fixed time intervals: Individual alcohol metabolism rates vary significantly based on factors like liver function, medications, and genetic factors

4. Not addressing underlying alcohol use disorder: Missed opportunity for intervention and referral

Conclusion

The safest approach is to ensure BAC is below 0.08% (80 mg/dL) before discharge, with clinical sobriety as the primary determinant. Documentation of both BAC and clinical assessment provides the strongest medicolegal protection and ensures patient safety.