Cases are grouped by surgical site using CPT groupings (see Inclusion Criteria).  Opioid equivalents are calculated using conversions derived from literature and given between anesthesia start and anesthesia end for each case.  This value is normalized to patient weight (kg) and duration of anesthetic (anesthesia end – anesthesia start, hours as a decimal).

Understanding opioid administration is important to help improve perioperative care.  There has been a dedicated focus on understanding opioid use within and outside the hospital and an equivalency is often used to compare opioid consumption.  As Oral Morphine Equivalent (OME) conversions are limited to medications routinely used outside of the operating room (OR) and omit some critical medications and routes used in the OR, a new algorithm was developed to incorporate medications used intraoperatively.  This equivalency is intended as an informational tool to help understand opioid use in the operating room. 

Anesthesia Start to Anesthesia End

All patients undergoing a procedure within the following primary anesthesia CPT groupings:

Cardiac

• Cardiac surgery with pump and > 1 year old (CPT: 00562)
• Cardiac surgery with hypothermic arrest (CPT: 00563)
• CABG with pump (CPT: 00567)
• Heart Transplant (CPT: 00580)
• CABG without pump (CPT:00566)

Spine (Adult): Age ≥ 18 years 

• Cervical spine and cord; not otherwise specified (CPT: 00600)
• Cervical spine and cord; patient in sitting position (CPT: 00604)
• Thoracic spine and cord; not otherwise specified (CPT: 00620)
• Thoracic spine and cord; thoracolumbar sympathectomy (CPT: 00622)
• Thoracic spine and cord, via an anterior transthoracic approach; not utilizing 1 lung ventilation (CPT: 00625)
• Thoracic spine and cord, via an anterior transthoracic approach; utilizing 1 lung ventilation (CPT: 00626)
• Lumbar region; not otherwise specified (CPT: 00630)
• Lumbar region; lumbar sympathectomy (CPT: 00632)
• Lumbar region; diagnostic or therapeutic lumbar puncture (CPT: 00635)
• Extensive spine and spinal cord procedures (eg, spinal instrumentation or vascular procedures) (CPT: 00670)

Spine (Pediatric): Age <18 years 

• Cervical spine and cord; not otherwise specified (CPT: 00600)
• Cervical spine and cord; patient in sitting position (CPT: 00604)
• Thoracic spine and cord; not otherwise specified (CPT: 00620)
• Thoracic spine and cord, via an anterior transthoracic approach; not utilizing 1 lung ventilation (CPT: 00625)
• Thoracic spine and cord, via an anterior transthoracic approach; utilizing 1 lung ventilation (CPT: 00626)
• Lumbar region; not otherwise specified (CPT: 00630)
• Extensive spine and spinal cord procedures (eg, spinal instrumentation or vascular procedures) (CPT: 00670)

Upper Abdomen

• Intraperitoneal - upper abdomen including laparoscopy; not otherwise specified (CPT: 00790)
• partial hepatectomy or management of liver hemorrhage (excluding liver biopsy) (CPT: 00792)
• Intraperitoneal - upper abdomen including laparoscopy; pancreatectomy, partial or total (eg, Whipple) (CPT: 00794)
• Intraperitoneal - upper abdomen including laparoscopy; gastric restrictive procedure for morbid obesity (CPT: 00797)

Lower Abdomen

• Procedures in lower abdomen including laparoscopy; not otherwise specified (CPT: 00840)
• Procedures in lower abdomen including laparoscopy; abdominoperineal resection (CPT: 00844)
• Procedures in lower abdomen including laparoscopy; pelvic exenteration (CPT: 00848)

Hysterectomy

• Intraperitoneal procedures in lower abdomen including laparoscopy; radical hysterectomy (00846)
• Vaginal procedures (including biopsy of labia, vagina, cervix or endometrium); vaginal hysterectomy (00944)

Knee/Popliteal

• Open or surgical arthroscopic procedures on knee joint; total knee arthroplasty (01402)

Hip

• Open procedures involving hip joint; total hip arthroplasty (01214)

Tonsil/Adenoid (Pediatrics): Age <18 years 

• Tonsil/Adenoid cases determined by Adenotonsillectomy value codes > 0

Any procedure not listed in one of the inclusion categories above

Success is not defined for these measures.

Other Measure Build Details:

Medication combinations are calculated using the medication concept IDs, route of delivery, and unit of measure as listed above.  Not all possible combinations are used as some routes or units are not used for certain medications in medical practice.  Remifentanil is not included in the opioid equivalency calculation due to its short duration of action and low context-sensitive half-time. Opioid equivalency is still calculated for these cases that use remifentanil but the cases are flagged as having “Remi”.  When an opioid dose cannot be calculated for a medication due to inadequate documentation, the opioid equivalency is returned for the remaining medications and the case is also flagged as having an opioid given with an “Unknown” dose.

If weight and/or anesthesia duration is missing for the case, the opioid equivalency is returned as NULL.

The following conversions were used for opioid equivalency conversions:

Example: A 10 kg patient receives 100mcg of fentanyl for induction (100 ug total for the case) for a 4.0 hour case.

1. First we calculate the /kg/hr IV OME for the case: 0.1mg fentanyl / 10 kg / 4.0 hour = 0.1/10/4 = 0.0025 OME mg/(kg*hr)
2. Next, we multiply by 3 to calculate PO OME: 0.0025 * 3 = 0.0075 mg/(kg*hr) PO OME
   • Each case grouping (Spine, Cardiac etc) a "standard" weight and case length has been assigned to help allow for case-to-case comparisons. Let’s pretend the standard chosen for this example is 20 kg patient and 3 hour case.
3. Then, we would report the following for this case: 0.0075 mg/(kg*hr) * 20kg * 3 hours = 0.45 PO OME 
   • The PO OME value is then used to convert and display the Fentanyl IV, Morphine IV and Morphine PO equivalent.
     • (ome.Value * 10.0 / 3.0)  -- Fentanyl IV
     • (ome.Value / 3.0)   --- Morphine IV
     • (ome.Value)   --- Morphine PO

*This measure will include valid MPOG cases defined by the Is Valid Case phenotype.

Not applicable

Provider(s) signed in for largest duration between anesthesia start and anesthesia end

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2. Dowell D HT, Chou R. CDC Guideline for Prescribing Opioids for Chronic Pain — United States, 2016. MMWR Recomm Rep 2016. 2016;65(No. RR-1):1–49.
3. McPherson ML. Demystifying Opioid Conversion Calculations: A Guide to Effective Dosing. Bethesda, MD: American Society of Health-System Pharmacists; 2009. 208 p.
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6. OpenAnesthesia , https://www.openanesthesia.org/
7. Koyyalagunta, D.  Pain Management, 2007, Chapter 113: Opioid Analgesics.  Pain Management, 113(2), 2007, Pages 939-964
8. Walker, PW, et. al. Switching from Methadone to a Different Opioid: What Is the Equianalgesic Dose Ratio?  Journal of Palliative Medicine.11(8), 2008, Pages 1103-1108