All of that huffing and puffing on the treadmill may be worthwhile to the patient awaiting surgery: A new retrospective study suggests that exercise programs aimed at increasing exercise tolerance before a surgical procedure may decrease morbidity and mortality.
“We’ve long known that physical fitness is a factor that appears to affect a patient’s chances for perioperative success,” explained Ruchir Gupta, MD, anesthesiology professor at Stony Brook University School of Medicine, in New York. He referred to over a dozen studies published over the last decade relating exercise capacity and perioperative outcome. “So we used a retrospective analysis to compile the existing literature, and we sought to determine if an exercise intervention program administered in the weeks before surgery can lead to better outcomes.”
Dr. Gupta and his colleague Michael Roizen, MD, of the Cleveland Clinic, in Ohio, searched Medline, the bibliographic database of the National Library of Medicine, for the terms “heart rate recovery,” “exercise capacity,” “maximum O2 [oxygen] consumption,” “perioperative outcome” and “physical fitness” used in studies between 1965 and 2015. Most cases concerned patients undergoing thoracic, vascular, abdominal and orthopedic surgeries. Case studies and abstracts were not included.
“In hindsight,” Dr. Gupta noted, “I would have wanted to include the term ‘functional capacity’ as well.”
Measuring Physical Fitness
The year of study, exclusion criteria, number of patients and topic studied were gathered from each report, and then the literature was organized by which test was used to determine exercise tolerance (heart rate recovery [HRR], metabolic equivalents [METS] or oxygen uptake) and which outcome was tested (cardiovascular disease, all-cause mortality or postoperative outcome). Of more than 62,000 patients in total, more than 36,000 underwent only HRR testing.
“There are a few methods of measuring physical fitness, which can lead to some confusion,” Dr. Gupta explained in a follow-up interview to his presentation at the 2015 New York State Society of Anesthesiologists PostGraduate Assembly. “METS is a survey that provides a broad view of a patient’s exercise capacity. HRR provides a physiologic variable that can be used to assess exercise capacity. One is not necessarily superior to another, and ideally, a combination of both assessments should be used in the future.”
A highlight of the analysis revealed the relationship between abnormal HRR and all-cause mortality. In patients 30 to 39 years of age who had an abnormal HRR, defined as a recovery under 42 beats per minute (bpm), surgery led to subsequent death in 24.3% of cases, compared with only 1.2% in patients who had an HRR over 42 bpm. The disparity only widened further in older patients. In patients over 60 years of age, those with an abnormal HRR subsequently died in 52.2% of cases, compared with only 19% of those with HRRs considered to be normal.
“The relationship between abnormal heart rate and outcomes is something that can’t be ignored,” Dr. Gupta noted. “It seems logical to believe that specific exercise programs aimed at increasing exercise tolerance before surgery can decrease morbidity and mortality postoperatively.”
Based on their findings, the authors suggested that after undergoing an exercise capacity test expressed in METS and an assessment of baseline HRR at one, two and five minutes, patients would be divided into three groups: a control group, an exercise group performing at suboptimal levels and an exercise group training at lactate threshold. Patients would undergo a 12-week intervention training program that uses the Bruce protocol—a test in which the patient works to ‘complete exhaustion’ on a treadmill as the treadmill speed and incline are increased every three minutes. The amount of time the patient remains on the treadmill can be used to estimate his or her maximum oxygen consumption.
“To my knowledge, no study to date has connected the dots and evaluated the efficacy of an exercise program before surgery,” Dr. Gupta noted. “Our next step is incorporating some of the newer studies in this review article and then implementing an exercise program on a small scale with controlled variables to assess for any benefit of the training program.”