OH is a common cardiovascular disorder whose clinical significance is increasingly being recognized, as OH can decrease quality of life and potentially worsen prognoses (8, 9). OH has been well studied and is closely associated with other common chronic diseases, including hypertension, congestive heart failure, diabetes mellitus, and Parkinson’s disease. The prevalence of OH in patients older than 65 years of age was found to be approximately 20% (10).
Most previous studies on OH were population-based cohort studies or performed in elderly individuals (11, 12). However, there are few studies on OH in hospitalized patients. Hospitalized patients are particularly vulnerable to the consequences of OH, particularly falls, because postural BP regulation may be disturbed by many common acute illnesses as well as by bed rest and drug treatment (2, 13). Feldstein reported that OH occurred in as many as 60% of hospitalized adults. Acute physiological and psychological changes due to illness, surgery and anesthesia occur in patients who undergo surgery. Postoperative OH has been well-documented (2). Hanada et al found that approximately 40% of 195 patients undergoing cardiothoracic and abdominal surgery experience OH during early postoperative mobilization (7).
Early mobilization is important after major orthopedic surgery to prevent morbidities and long hospital stays. Postoperative OH can prevent early mobilization and has been observed in patients undergoing major orthopedic surgeries. Postoperative OH can lead to failed physiotherapy in patients who have undergone hip arthroplasty, and its incidence has been reported to be 40%-50% (6, 14). Associations between OH and spine surgeries and spinal cord injuries have also been found. Edward et al found that 22 of 190 patients who underwent cervical spine surgery (11.6%) developed postoperative OH. The authors found that the presence of neurological deficits is a risk factor for postoperative OH (3). The link between spinal cord injuries (SCIs) and the development of OH has been observed (15). Postural changes during physiotherapy and mobilization have been shown to induce clinically significant OH in 74% of SCI patients, with symptoms in 59% of patients (15). Significant differences in the incidence of OH between patients with compressive cervical myelopathy and healthy controls were found in Srihari’s study (16). Furthermore, McKinley et al found that traumatic SCI patients had a significantly higher incidence of OH than did nontraumatic SCI patients (36.7% vs 5.3%) (17).
Previous studies have shown that early ambulation can decrease the length of hospital stay and perioperative complications and improve functional outcomes in adolescent and adult patients undergoing correction surgery for spinal deformities (18, 19). Thus, we asked patients in this group to perform out-of-bed exercises and stand within 72 hours after surgery. Postoperative OH may occur and affect recovery in these patients. However, until now, there have been no studies on postoperative OH following posterior spinal fusion surgeries for spinal deformity correction in adolescents. In the current study, we determined the incidence of postoperative OH following posterior spinal fusion for the treatment of adolescent spinal deformities. Two hundred and twenty-five (72.1%) of 312 adolescent patients who underwent correction surgeries for spinal deformities and performed out-of-bed exercises early and stood within 72 hours after surgery developed postoperative OH, which mostly occurred within 2 days of standing, and all cases completely resolved after the fifth day of standing. The presence of postoperative OH significantly increased the length of hospital stay. However, no differences in the SRS-22 score were found between the patients with and without postoperative OH.
The risk factors for postoperative OH following spine surgeries remain unclear. Neurological deficits and traumatic SCI have been reported to be associated with a higher incidence of postoperative OH (3). In our study, we found that age, sex, the number of levels instrumented and fused, whether laminectomy or osteotomy was performed during the surgery, the postoperative hemoglobin level and the postoperative albumin level were not significantly associated with postoperative OH following posterior spinal fusion surgeries for the correction of spinal deformities in adolescent patients. Significant associations between PONV, willingness to ambulate, length of postoperative exercises of the lower limbs and postoperative OH were found. The association between PONV and OH was reported in a previous study. Franz et al found that female patients with preoperative OH had an increased risk of PONV (20). For patients with risk factors for PONV, including the female sex, a history of motion sickness or previous PONV, a nonsmoking status, and the use of postoperative opioid drugs, therapies should be given to decrease the occurrence or severity of PONV and postoperative OH. Early postoperative exercise, including lower limb strength training, is an essential component of rehabilitation protocols following posterior spinal fusion surgeries and can improve function and shorten the hospital stay (21–23). According to our findings, better patient education of early postoperative ambulation to encourage patients to perform early postoperative out-of-bed exercises and postoperative strategies to increase the mobility of the lower limbs may be helpful to decrease the incidence of postoperative OH following posterior spinal fusion surgeries for the treatment of adolescent spinal deformities.