This phenotype determines if a halogenated anesthetic agent was administered between Anesthesia Start and Anesthesia End. It relies upon the Induction Start, Induction End, and Maintenance End  phenotypes to determine when the halogenated anesthetic was administered. If inspired% gas is documented then use inspired% values to determine if valid anesthetic gas, else use expired% gas values.

The following time periods are assessed to determine when halogenated agents were administered. If any of these time periods are unknown due to missing documentation, the time period is labeled as 'unspecified.' See step 4 for more information about how 'unspecified' time periods are assessed for halogenated agent use.

Prior to Induction: Anesthesia Start to Induction Start

Induction: Induction Start to Induction End

Maintenance: Induction End to Maintenance End 

After Maintenance: Maintenance End to Anesthesia End

Step 1. If <2 non-artifact halogenated gas values are documented between Anesthesia Start and Anesthesia End, return 0 - 'No.'

Step 2. Assess if case has >=2 non-artiffact halogenated gas values (inspired or expired) between Induction Start to Induction End.

• If unable to determine induction period duration, continue to step 3.
• If <2 non-artifact halogenated gas values during induction period, continue to step 3.
• If >=2 non-artifact halogenated gas values, assess duration of maintenance period (Induction End to Maintenance End).
  • If Maintenance period is <=10 minutes AND:
    • If <2 non-artifact halogenated gas values during the Maintenance period, return 1 - 'Induction Only.'
    • If >=2 non-artifact halogenated gas values during the Maintenance period, return 2 - 'Induction & Maintenance'
  • If Maintenance period is >10 minutes AND:
    • If <5 non-artifact halogenated gas values during Maintenance period, return 1 - 'Induction Only.'
    • If >=5 non-artifact halogenated gas values during Maintenance period, return 2 - 'Induction & Maintenance'
  • If unable to determine duration of maintenance period, continue to step 4.

Step 3. Assess if case has >=2 non-artifact halogenated gas values (inspired or expired) during the maintenance period (Induction End to Maintenance End).

• If unable to determine maintenance period duration, continue to step 4.
• If Maintenance period is <=10 minutes AND:
  • If >=2 non-artifact halogenated gas values during Maintenance period, return 3 - 'Maintenance Only.'
  • If <2 non-artifact halogenated gas values during Maintenance period, return 4 - 'Yes - Unspecified.'
• If Maintenance period is >10 minutes AND:
  • If >=5 non-artifact halogenated gas values during Maintenance period, return 3 - 'Maintenance Only.'
  • If <5 non-artifact halogenated gas values during Maintenance period, return 4 - 'Yes - Unspecified.'

Step 4. Assess 'Unspecified' time periods.

• Case has >= 5 non-artifact halogenated gas values between Anesthesia Start and Anesthesia End, and maintenance and/or induction timeframes cannot be determined.

*Note:

• Total count of all inspired or expired values must be >= 5. Missing minutes between valid values will have the last value carried forward if <= 5 minutes.
• These readings do not have to be consecutive or of the same type of volatile gas.
• For institutions that only report anesthetic gases every 5 minutes, >= 2 halogenated gas values must be present to return values 1-4.
• For this phenotype induction end date and time will be the same as maintenance start.