PH Awareness Month - Post #24

I have seen time and time again on the PH boards questions about needing surgeries not related to PH, and whether or not we can be under anesthesia. The PHA has a great response to this question, and while you can read it here, I thought I would post it, too. I honestly forget all the time which anesthetic is ok and which is not! It's important for PHers to know, because it can literally mean life and death!

Question: What issues should PH patients consider before undergoing general surgery, specifically relating to general anesthesia?

Answer: Anesthesia and general surgery in patients with pulmonary arterial hypertension (PAH) are associated with increased risk of morbid events and death due mainly to right heart failure, abnormal heart rhythms, and postoperative low oxygen levels. Successful management of patients with PAH undergoing general surgery requires a multidisciplinary approach involving the pulmonary hypertension specialist, an anesthesiologist well-versed in the management of PH patients and right heart failure, and an experienced surgeon. A careful analysis of the pre-operative and operative risk factors, and a plan for intra-operative management and early recognition and treatment of post-operative complications should be undertaken.

There is limited literature describing the peri-operative risk of morbidity and mortality in patients with PAH undergoing general, non-heart surgery. However, compared with other high risk patient populations undergoing general surgery, the peri-operative risk is greater in PAH patients. The risks seem to be higher in PAH compared to other causes of PH. The complications can occur within several days of the surgery. Peri-operative risk assessment involves an individualized approach taking into account the type of surgery, the functional capacity (World Health Organization [WHO] functional class), hemodynamic severity of PAH at right heart catheterization, the functional status of the right side of the heart, and any other medical condition present.

Those patients who undergo low risk operations and have low risk clinical features will generally have a good outcome. Those who undergo intermediate- or high-risk surgery and/or have high-risk clinical features may have poorer outcomes. Low-risk operations/procedures include skin, cataract, and breast surgery and endoscopic procedures (i.e. gastrointestinal, urinary tract). Intermediate-risk operations include carotid endarcterectomy, head and neck, gynecologic, gastrointestinal/intra-abdominal, orthopedic, prostate and thoracic surgery. High-risk operations include major surgery that is done in an emergency situation, aortic or other major blood vessel surgery, and liver transplantation.

Clinical features that predict a low risk include good functional status, in that the patient does not have symptoms of shortness of breath, fatigue , chest pain or lightheadedness with ordinary physical activity (WHO class I), favorable hemodynamics at right heart catheterization, good right heart function on echocardiogram (heart ultrasound) and normal lab tests. Features that predict a high risk include poor functional status (patient has marked limitation of physical activity and can be symptomatic even at rest [WHO class III, IV]), unfavorable hemodynamics at right heart catheterizaiton, and echocardiogram showing evidence of an enlarged, thickened and/or poorly functioning right side of the heart. Laboratory studies consistent with a stressed right side of the heart (high B-type natriuretic peptide [BNP]) and reduced kidney function are also predictors of high risk with general surgery. Other concomitant medical conditions, in particular a history of pulmonary embolism (blood clot to the lungs) can also increase the risk of general surgery.

In situations of elective general surgery, a careful pre-operative evaluation should be performed by an anesthesiologist experienced in the care of the PH patient. The aneshesiologist in communication with the surgeon and PH specialist can determine the best monitoring approach (which in cases of intermediate and high- risk surgery will often require the placement of a catheter in the right side of the heart to guide therapy), the best anesthetic approach (limited regional, epidural block, or general anesthesia), and a plan for pre-operative, intra-operative, and post-operative management of the pulmonary hypertension and potential worsening of right heart function.

Nerve blocks are usually considered in patients undergoing surgery to a foot or arm. Epidural anesthesia (a catheter placed in the back just outside of the sack of the spinal cord) can be successfully employed for repair of an artery in the leg, gall bladder surgery, Cesarian section, and other gynecologic procedures.

General anesthesia is usually reserved for higher risk operations. Most peri-operative deaths occurring in patients receiving general anesthesia are associated with the surgical procedure itself and the underlying disease rather than the general anesthesia per se. Certainly, there are some anesthetic agents that should be used preferentially and others avoided in PH compared to other patient populations. The experienced anesthesiologist will choose the most appropriate agent or combinations of agents depending on the type of operation, and the particular patient profile.

Peri-operative management includes assessment and optimization of the patient’s baseline clinical state before the surgery, avoidance of factors that can cause the pulmonary arteries to constrict, careful management of ventilation to assure optimal oxygen delivery, the administration of appropriate drugs that dilate the pulmonary vessels, and early post-operative identification and treatment of right sided heart failure and any factors that could predispose to its development.

In summary, when undergoing general surgery the most important consideration from the PH patient’s perspective is to assure that the team involved in the pre-, intra-, and post-operative care is experienced in the management of patients with PH/PAH.

Question answered by:Teresa De Marco, M.D.UCSF Medical CenterSan Francisco, Calif.

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