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

A. No Nitrous Agent is returned If < 2 valid nitrous gas values between Anesthesia start - End 

B. Induction Only is returned if one of the following is true:

• Case has >= 2 nitrous inspired gas values above threshold for >= 2 minutes between Induction Start and Induction End
• Case has >= 2 nitrous expired gas values without inspired values above threshold for >= 2 minutes between induction start and induction end

C. Maintenance Only is returned if Maintenance duration is > 10 minutes AND any of the following are true:

• Case has >= 5 inspired or only expired values AND timeframe cannot be determined
• Case has < 2 inspired or only expired values during induction
• Maintenance is <=10 minutes Case has < 5 inspired or only expired values during maintenance

D. Induction and Maintenance is returned if at least one criteria from BOTH Step B and C are met 

E. 'Yes - unspecified' (4) is returned if one of the following is true:

• Case has >= 5 inspired or only expired values AND timeframe cannot be determined
• Case has >= 5 inspired or only expired values across induction, maintenance or unspecified time.
• Cases where Anesthesia Start - Anesthesia End is <= 10 minutes
  • Induction duration < 2 minutes
  • Maintenance duration < 2 minutes 
• Cases where maintenance period <= 10 minutes
  • Case has < 2 inspired or only expired values during induction period
  • Case has < 2 inspired or only expired values during maintenance period
  • Case has < 5 inspired or only expired values during an unspecified time period
• Cases where maintenance period > 10 minutes
  • Case has < 2 inspired or only expired values during induction period
  • Case has < 5 inspired or only expired values during maintenance period
  • Case has < 5 inspired or only expired values during an unspecified time period

*Note:

• Total count of all inspired or only expired values must be greater than or equal to 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 nitrous MPOG concept.
• For institutions that only report anesthetic gases every 5 minutes, = 2 nitrous gas physiologic values must be present to return values 1-4.
• For this phenotype induction end date and time will be the same as maintenance start.
• For institutions who submit both inspired and expired gas % values, expired values are ignored. For institutions who do not submit inspired gas % values, expired % values are used to determine if anesthetic gas was administered.