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The High Altitude Simulation Test (HAST) is a specialized diagnostic procedure designed to assess a patient's respiratory function under conditions that mimic high-altitude environments, specifically at elevations around 8,000 feet. This test is particularly relevant for individuals with pre-existing respiratory conditions, as it helps determine their need for supplemental oxygen during air travel or when visiting high-altitude locations. The procedure begins with the establishment of baseline measurements, including blood pressure, heart rate, rhythm, oxygen saturation (SaO2), and a dyspnea rating, which evaluates the patient's level of breathlessness. Following this initial assessment, the patient is exposed to a hypoxic gas mixture containing approximately 15.1 percent oxygen for a duration of 20 to 30 minutes, or less if symptoms arise. Throughout the test, the patient is closely monitored both at rest and during mild physical exertion, with vital signs and dyspnea ratings meticulously recorded to identify any significant changes in their condition. Should the patient exhibit notable symptoms during the initial phase, the test is repeated while administering supplemental oxygen to ascertain the precise amount required to alleviate symptoms at higher altitudes. A comprehensive written interpretation and report of the findings are subsequently provided by a physician or qualified healthcare professional. It is important to note that CPT® Code 94453 is specifically used when the test is conducted with both the initial hypoxic exposure and the subsequent supplemental oxygen titration, while CPT® Code 94452 is designated for the HAST performed without the second test involving supplemental oxygen.
© Copyright 2025 Coding Ahead. All rights reserved.
The High Altitude Simulation Test (HAST) is indicated for patients who may be at risk for hypoxia or other respiratory complications when exposed to high-altitude environments. The following conditions may warrant the performance of this test:
The High Altitude Simulation Test (HAST) involves several critical procedural steps to ensure accurate assessment of the patient's respiratory function under simulated high-altitude conditions:
Post-procedure care for patients who have undergone the High Altitude Simulation Test (HAST) typically involves monitoring for any lingering symptoms or complications resulting from the test. Patients may be advised to rest and hydrate adequately following the procedure. The physician will review the results of the test with the patient, discussing the implications for future travel to high-altitude locations and the necessity of supplemental oxygen if indicated. Any recommendations for follow-up care or additional testing will also be provided based on the patient's individual response and medical history.
| Short Descr | HAST W/OXYGEN TITRATE | Medium Descr | HIGH ALTITUDE SIMULATJ W/PHYS I&R W/O2 TITRATION | Long Descr | High altitude simulation test (HAST), with interpretation and report by a physician or other qualified health care professional; with supplemental oxygen titration | Status Code | Active Code | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 1 - Diagnostic Tests for Radiology Services | Multiple Procedures (51) | 0 - No payment adjustment rules for multiple procedures apply. | Bilateral Surgery (50) | 0 - 150% payment adjustment for bilateral procedures does NOT apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 0 - Payment restriction for assistants at surgery applies to this procedure... | Co-Surgeons (62) | 0 - Co-surgeons not permitted for this procedure. | Team Surgery (66) | 0 - Team surgeons not permitted for this procedure. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | APC Status Indicator | STV-Packaged Codes | Type of Service (TOS) | 1 - Medical Care | Berenson-Eggers TOS (BETOS) | T2D - Other tests - other | MUE | 1 | CCS Clinical Classification | 38 - Other diagnostic procedures on lung and bronchus |
| 26 | Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number. | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | CR | Catastrophe/disaster related | GC | This service has been performed in part by a resident under the direction of a teaching physician |
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| 2013-01-01 | Changed | Description Changed |
| 2005-01-01 | Added | First appearance in code book in 2005. |