CMS and OIG Focus on Improper ICD-10-PCS Ventilation Coding

The Medicare-Severity Diagnostic Related Groups (MS-DRGs) with ICD-10-PCS mechanical ventilation code(s) have been cited by the Centers for Medicare and Medicaid Services (CMS) and the Office of Inspector (OIG) as problematic and a compliance risk. In a June 2021 CMS Medicare Learning Network (MLN) publication #17107 ”revised”, this included mechanical ventilation concerns as well as Modifier 59. In this particular CMS compliance newsletter, they discuss the incorrect procedure coding for mechanical ventilation. You can access this document at: SE17017 (

Interesting that in the June MLN, CMS quotes the OIG 2016 report titled, “Medicare Improperly Paid Hospitals for Beneficiaries Who Had Not Received 96 or more Consecutive Hours of Mechanical Ventilation”.  An example provided is this OIG report regarding documentation and ICD-9-CM coding is the following:

  • Medical record documentation (ventilation records) showed that a patient was in the hospital for 5 days and received a total of 91 hours of ventilation, but the procedure code on the claim indicated 96 or more consecutive hours of mechanical ventilation was provided. This resulted in grouping the claim to a MS-DRG that led to a higher and incorrect payment, which Medicare later recovered from the hospital.

This particular OIG report was published back in 2016 but is still available at the following link: Medicare Improperly Paid Hospitals for Beneficiaries Who Had Not Received 96 or More Consecutive Hours of Mechanical Ventilation (A-09-14-02041) (

When coding encounters today with mechanical ventilation we need to look at the specific ICD-10-PCS guidelines and rules. The Extracorporeal Assistance and Performance section of ICD-10-PCS is where you go to locate the code(s) to assign for mechanical ventilation. This is when the respiratory equipment is outside the body and is used to assist/perform physiological functions and ICD-10-PCS has three root operations that can be chosen: Assistance, Performance and Restoration.

Mechanical ventilation can be “noninvasive” such with a face mask , nasal mask/pillow, which is considered to have the ICD-10-PCS root operation of “Assistance”. Mechanical ventilation is also considered to be “invasive”; this is when it is provided via an interface such as endotracheal intubation (nonsurgical) or tracheostomy (surgical) procedure. The endotracheal intubation procedure is coded when the placement is either oral or nasal. There are two ICD-10-PCS codes to consider as follows:

  • 0BH17EZ Insertion of tracheal airway into trachea, via natural or artificial opening
  • 0BH18EZ Insertion of endotracheal airway into trachea, via natural or article opening endoscopic

The invasive mechanical ventilation completely takes over the physiological function of breathing by extracorporeal means and thus is classified to the root operation of “Performance” in ICD-10-PCS.

In ICD-10-PCS there are specific codes to select from when mechanical ventilation services are provided. Each ICD10PCS code describes the duration (time in hours) that the patient is on mechanical (respiratory) ventilation:

  • 5A1935Z Respiratory Ventilation, less than 24 Consecutive Hours
  • 5A1945Z Respiratory Ventilation, 24-96 Consecutive Hours
  • 5A1955Z Respiratory Ventilation, greater than 96 Consecutive Hours

There is also a PCS code for nonmechanical ventilation: 5A19054 Respiratory Ventilation, single nonmechanical.

The ventilation flow sheet (documents) from the Respiratory Therapist is critical and the primary source for counting and validating the number of consecutive mechanical ventilation hours that the patient was placed on. Also, the coding professional should review the Physician Orders and the Progress notes for any documentation describing the intubation and the mechanical ventilation treatment duration. Being these are “time-based” PCS codes, having documentation to support the number of consecutive hours is vital.

In my professional experience I have seen coding issues (errors) occur with the inpatient procedure coding of consecutive mechanical ventilation hours. Often there is an issue with the counting of the actual hours; i.e., start time and end time. As the OIG stated, the wrong code can lead to an incorrect MS-DRG and an overpayment. Counting the duration or number of hours of mechanical ventilation can be confusing and problematic for some coding professionals, thus a review of the guidelines can be beneficial. Here are some important considerations when counting the ventilation start time:

  • The time when the Endotracheal intubation in the hospital or hospital emergency department, followed in initiation of mechanical ventilation was performed;
  • The initiation of the mechanical ventilation through a tracheostomy which was performed in a hospital or hospital emergency department;
  • If the patient was previously intubated or if they have a tracheostomy AND are on mechanical ventilation and come to the hospital, then the time of admission is used as the starting time.

Coding professionals should only count the actual hours that the patient is on mechanical ventilation. It’s important to remember that the “weaning” period off of the mechanical ventilation is to be counted. When the patient is ultimately extubated then the duration ends and the ventilation is turned off, which ends the weaning period and the counting of hours. Also, if the patient is only on the mechanical ventilation during the night, then count the duration as the time the patient is actually put on a ventilator, often using ICD-10-PCS code 5A1935Z – less than 24 consecutive hours. The ending time for mechanical ventilation occurs when:

  • The endotracheal tube is removed (extubation)
  • There is a discontinuation of ventilation for a patient with tracheostomy after the weaning period is completed.
  • When the patient is discharged or transferred while STILL ON mechanical ventilation.

The ICD-10-PCS codes for mechanical ventilation would not be reported if it is being used during a surgical procedure. The mechanical ventilatory support that is provided to a patient during surgery is considered an integral part of the surgical procedure and thus should not be coded separately. Another tip is to talk with your Respiratory Therapy department manager about mechanical ventilation treatment and the weaning off documentation.

The American Hospital Association (AHA) ICD-10-CM/PCS Coding Clinic has published clarification and guidance on the ICD-10-PCS coding of mechanical ventilation in the past (this is not an all-inclusive list):

  • First Quarter 2018 – Mechanical Ventilation Using patients Own Equipment
  • First Quarter 2017 – Newborn Noninvasive Ventilation
  • Fourth Quarter 2014 – BIPAP Delivered Via A Tracheostomy
  • Fourth Quarter 2014 – Continuous Positive Airway Pressure Delivered Via Tracheostomy
  • Fourth Quarter 2014 – Duration of Mechanical Ventilation During Weaning Period
  • Fourth Quarter 2014 – Endotracheal Intubation with Mechanical Ventilation for Acute Respiratory Failure

It would be a good idea to review these issues of AHA Coding Clinic with your coding staff and share with Clinical Documentation Integrity staff as well. Another good resource to help understand the coding of mechanical ventilation is the AHA ICD-10-CM and ICD-10-PCS Coding Handbook.

Be sure to include in your next hospital inpatient coding audit, those MS-DRGs with mechanical ventilation hours in the title/description and inpatient encounters with the mechanical ventilation ICD-10-PCS code assigned. Include in the audit data report for encounter selection the length of stay for the encounters and discharge disposition as well. Being that we’ve seen a large volume of patients in the hospital with COVID-19 during the Public Health Emergency and these patients were on a ventilator, this points to an area to audit also. Check your annual coding audit plan, as it would be a best practice to include auditing the mechanical ventilation PCS codes in your plan. Look to external HIM Coding resources also to help with specific audits like those focusing on ICD-10-PCS code(s) for Mechanical Ventilation. Being proactive is a best practice when it comes to coding compliance!

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