With orthopedic surgeries becoming more common at higher altitudes, it is important that we understand the increased risks of surgery at higher elevations. Patients locally (Eagle, Summit, Pitkin, Grand, Lake and other high-altitude counties in Colorado) and those that travel from all over the world to undergo surgery by our orthopedic surgeons are at an increased risk for complications post-surgery. Patients that have surgery at a lower altitude and return to higher elevations post-surgery are also at higher risk for post-operative complications. These risks are higher for everyone having surgery at altitude regardless if you live at higher elevations or are from sea level.

High altitude is defined as 8-12,000 feet. However, increased surgical risks are seen starting at 4000 feet. There are no differences for increased risk if you are acclimated to the altitude (live here) or are visiting. The increased risk of surgery at high altitude is the same for all.

High altitude increases the coagulation state of blood (clotting ability) and hyperventilation (breathe out more than you breathe in), and oxygen saturation of blood and tissues is 10% lower at high altitude compared to low altitudes, leading to a hypoxic state. The hyperventilation state promotes the hypercoagulable state which causes the immune system to respond with a pro-inflammatory state. Acclimation does occur, we adapt, are able to breathe easier and function normally as our bodies make more red blood cells to compensate for the lower available oxygen in the air. However, the hypercoagulability of blood remains, because the hyperventilation state is sustained at high elevations (even if you live here). At high elevations there are physiological differences in pulmonary circulation (blood through the lungs), heart function, and fluid imbalances which induce dehydration that accompanies blood changes contributing to the increased risk of surgery at high elevations.

Risk factors for blood clots from orthopedic surgery for the general population include: decreased mobility or sitting around more, length of surgery (greater than 4 hours increases blood clot risk), joint replacements, smoking, diabetes, and other illnesses.

In general, there is a 40-60% chance of a blood clot following knee or hip replacement surgery. At altitude that risk doubles. There is a 3.8 times greater risk of thromboembolism (blood clots) for knee surgeries at high elevations. Total shoulder replacement surgery also demonstrates a 2-times greater risk of pulmonary embolism at altitude or 39.5%, compared to a 15% chance at sea-level. For rotator cuff repair of the shoulder, there is also an increased risk for blood clots. There is a 1.4-times greater risk for pulmonary embolism (blood clot in the lungs) for lumbar fusions at high altitude. Higher elevation is an independent risk factor for blood clots which lasts up to 90 days post orthopedic surgery.

Anesthesia at high altitude has its own risk. The sustained hyperventilation state at high altitude also leaves the patient more vulnerable to hypoxia and pulmonary edema with anesthesia. These risks can be minimized, however remain elevated for surgeries requiring general anesthesia above 4000 feet.

For patients returning to high altitude following surgery at lower elevations, there exists multiple risks due to hypercoagulable state, increased inflammatory response, and hyperventilation that higher elevations induce. Acclimatization to high altitude is lost within 2 days of being at a lower elevation and can take 3-4 months to achieve again. In as little as 2 hours after arriving at high altitude, the body initiates the above changes and this puts the post-operative patient returning to altitude at risk for a multitude of complications: dehydration, thromboembolisms, hypoxia, atelectasis, and pulmonary edema.

I recently spoke with a patient that grew up in Leadville (10,151 feet) and lives in Summit County (average of 7947 feet). She underwent hip surgery (twice) in Denver. Upon returning to Summit County, she developed high altitude pulmonary edema (HAPE) both times. When she underwent an ankle surgery in Edwards, the surgeon prophylactically treated her for high altitude sickness given her previous history. She did not develop HAPE, but was hypoxic and required oxygen therapy following surgery for a few days. She is a prime example that even those living their entire lives at altitude are susceptible to these increased risks from surgery.

These risks can be minimized by drinking plenty of fluids, using compression socks (TED hose) or sequential compression devices (SCDs), blood thinners (aspirin, Eliquis, or the like), doing ankle pumps and glute squeezes, and getting up and walking around every 1.5-2 hours for 10-15 minutes, all of which help decrease the likelihood that patients will experience blood clots following orthopedic surgeries.

To reduce respiratory or lung related complications it is important to do deep breathing exercises or incorporate the use of an inspirometer post-surgery, use supplemental oxygen if necessary, as well as continue to do these exercises after returning from a lower elevation for at least 2-3 weeks.

High altitude is an independent risk factor for orthopedic surgery complications. However, these increased risks have been seen in trauma patients and other surgical patients as well. The hyperventilation state, hypercoagulability, and elevated inflammatory response are not isolated to orthopedic patients, but exists in everyone living at and visiting higher elevations.

— Jessica Guthrie, BSN, RN

References

Cancienne, J., Diduch, D., & Werner, B. (2017). High altitude is an independent risk factor for postoperative symptomatic venous thromboembolism after knee arthroscopy: A matched case-control study of Medicare patients. Arthroscopy: The Journal of Arthroscopic and Related Surgery 33(2). https://dx.doi.org/10.1016/j.artho.2016.07.031

Damodar, D., Donnally, C., Sheu, J., Law, T., Roche, M., & Hernandez, V. (2018). High altitude an independent risk factor for venous thromboembolisms after total hip arthroplasty. Journal of Arthroplasty 33(8), 2627-2630. https://doi.org/10.1016/j.arth.2018.03.045

Damodar, D., Vakharia, R., Vakharia, A., Sheu, J., Donnally, C., Levy, J., Kaplan, L., & Munoz, J. (2018). A Higher altitude is an independent risk factor for venous thromboembolisms following total shoulder arthroplasty. Journal of Orthopedics 15(4). https://doi.org/10.1016/j.jor.2018.09.003

Donnally, C., Vakharia, A., Sheu, J., Vakharia, R., Damodar, D., Shenoy, K., & Gjolaj, J. (2019). High altitude is an independent risk factor for developing pulmonary embolism, but not a deep vein thrombosis following a 1 to 2 level lumbar fusion. Global Spine Journal 9(7) 729-734. https://doi.org/10.1177/2192568219828349

Tyson, J., Bjerke, B., Genuario, J., & Noonan, T. (2016). Thromboembolic events after arthroscopic knee surgery: Increased risk at high elevation. Arthroscopy: The Journal of Arthroscopic and Related Surgery 32(11), 2350-2354. https://dx.doi.org/10.1016/j.arthro.2016.04.008

Wani, Z. & Sharma, M. (2017). High altitude and anesthesia. Journal of Cardiac Critical Care 1(1), 30-33. https://doi.org/10.1055;s-0037-1604203