Introduction
Sleep is an important yet underappreciated factor in recovery from surgery (Closs, 1992; Gong et al., 2015; Redeker & Hedges, 2002), but the postoperative hospital stay is often characterized by poor sleep interrupted by frequent disruptions. Sleep disturbances are very common following total joint arthroplasty (TJA), particularly during the early postoperative period (Chen et al., 2016; Kirksey et al., 2015; Manning et al., 2017). Prior studies have documented the potential magnitude of this problem, with continuous polygraphic recording demonstrating a mean cumulative sleep time for the first two nights, daytime sleep included, of less than 2 hours (Aurell & Elmqvist, 1985). Deeper stages of sleep are significantly diminished early after surgery (Friese et al., 2007), with rapid eye movement (REM) sleep effectively eliminated on the first postoperative night following TJA (Krenk et al., 2012). When compared with patient perception, the severity of these sleep disruptions is vastly underestimated by healthcare providers (Florin et al., 2005).
Reasons for poor-quality sleep are multifactorial but include ambient noise levels, an unfamiliar environment, postoperative pain, the inability to lie comfortably, and medication side effects (Cutrufello et al., 2020; Delaney et al., 2018; Ellis & Dudley, 1976; Redeker & Hedges, 2002). These predisposing factors to sleep disturbances are exacerbated by frequent disruptions from hospital staff. Nursing protocols on postsurgical units typically require regular assessment of vital signs in all patients every 3-4 hours, including during the overnight period where patients may otherwise have their best opportunity to sleep when free from many of the other in-hospital interruptions.
Although long accepted as standard of care, the necessity of these ritualized overnight vital sign checks has never been studied among elective TJA patients. Given the increased focus on improving inpatient patient satisfaction (Mistry et al., 2016; Piper & Tallman, 2016) as well as the demonstrated safety of ambulatory joint replacement surgery in both healthy patients and those with well-controlled comorbidities (Basques et al., 2017; Goyal et al., 2017), it is reasonable to question whether these vital sign checks remain medically necessary for the majority of elective arthroplasty patients who continue to stay as an inpatient following surgery. The goals of this study were to (1) assess for any benefits of having checked overnight vital signs among a large cohort of elective arthroplasty patients and (2) identify patient-specific factors that may predict those more likely to have normal versus abnormal overnight vital signs. Our hypothesis is that it is safe to allow the vast majority of elective arthroplasty patients to sleep uninterrupted through the night.
Methodology
We retrospectively identified a cohort of 419 patients who underwent elective total hip arthroplasty or total knee arthroplasty between 2014 and 2016 at our academic medical center. During this time, all TJAs were performed as inpatient procedures. Unicompartmental and revision arthroplasty patients were excluded from the analysis. Medical records were reviewed for basic patient demographics, comorbidities, and surgical factors including intraoperative estimated blood loss (EBL), operative time, type of anesthesia, and preoperative American Society of Anesthesiologists (ASA) classification (see Table 1). Institutional review board approval was obtained prior to any data collection or data analysis being performed.
Our standard institutional protocol requires postoperative vital signs in TJA patients every 4 hours by a nursing assistant. If any vital signs were abnormal, they would be repeated by a registered nurse. All vitals measurements were performed using a combination unit with an advanced touch screen monitor with wireless electronic medical record connectivity (Connex 6400 Vital Signs Monitor; Welch Allyn, Skaneateles Falls, NY). When noted, abnormal vital signs were communicated to the orthopaedic resident, who intervened as necessary after consulting with senior orthopaedic house staff, attending orthopaedic surgeons, or a medicine consult physician.
Inpatient hospital records were reviewed, and all inpatient vital signs recorded on postoperative days (PODs) 0-3 were collected. Vital signs of interest were temperature (TEMP), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and oxygen saturation (O2). We defined the daytime period as 6:00 a.m. through 10:00 p.m., and we defined the nighttime period as 10:01 p.m. through 5:59 a.m. Vital signs were defined as abnormal if they were outside of the normative range for our institution (see Table 2). Vital signs that differed more than 10% from the upper or lower range of the accepted range were labeled as concerning. For all instances of abnormal nighttime vitals, we then looked at what actions were taken as a result of the reading. Finally, we examined records for any adverse events that occurred during the inpatient hospitalization.
We used a Generalized Estimating Equation, utilizing a logistic link for categorical variables and continuous variables, to examine for any correlation between abnormal nighttime vital signs and patient demographics, surgical variables, or abnormal daytime vital signs. Statistical analysis was performed using SPSS Statistics for Windows, version 21.0 (IBM; Armonk, NY). A p value of less than .05 was considered statistically significant.
Results
One patient (0.2%) was discharged on POD 0, 13 (3.1%) were discharged on POD 1, 111 (26.5%) were discharged on POD 2, and 294 (70.2%) were discharged on POD 3 or beyond. Multiple vital signs were taken during each overnight period, with the goal of every 4 hours per nursing protocols. The vast majority of these nighttime vital signs fell within defined normal ranges, including TEMP (97.8% normal), HR (87.5% normal), SBP (85.8% normal), DBP (84.4% normal), and O2 (99.4% normal). The frequency of any abnormal vital sign during that monitoring period is presented in Table 3.
Abnormal and even concerning vital signs rarely led to interventions. During the first overnight period (PODs 0-1), one patient was given a single dose of a [beta]-blocker for hypertension (SBP: 157) and another patient was transfused one unit of packed red blood cells in the PACU in response to persistent tachycardia (HR: 115). This patient had an EBL of 2,500 ml and a postoperative hemoglobin (Hb) level of 8.3. During the second overnight period (PODs 1-2), two patients were transfused one unit of packed red blood cells for persistent tachycardia (HR: 108-114) in the setting of postoperative anemia (EBL: 125 ml with postoperative Hb: 7.1, and EBL: 400 ml with postoperative Hb: 7.7). A lower extremity ultrasonography was also ordered overnight PODs 1-2 in another patient for ongoing tachycardia, which was negative (HR: 114). During the third overnight period (PODs 2-3), one separate patient was sent for a computed tomography angiography for persistent tachycardia, which was positive for pulmonary embolism, and anticoagulation was initiated (HR: 116). Another patient with persistent tachycardia overnight (HR: 112-115) had a diagnosis of hospital-acquired pneumonia with infiltrates on chest radiograph. A 7-day course of clindamycin and a short course of steroids/nebulizers were initiated, which resolved the patient's symptoms. Finally, one patient had a low O2 saturation (85%) and was given a nebulizer, steroids, and supplemental oxygen via nasal cannula. In each of these cases, there were abnormal vital signs during the preceding daytime period that were similar to the nighttime vital signs that prompted intervention. No overnight interventions were ever performed for abnormalities in overnight temperature or DBP vital signs.
Abnormal nighttime vital signs did not correlate to age or sex but demonstrated clear associations with several patient comorbidities and surgical factors (see Table 4). A higher preoperative ASA score correlated with an increased likelihood of having abnormal nighttime SBP (odds ratio [OR]: 1.64; 95% confidence interval [CI] = 1.01-2.67, p = .045). A history of smoking correlated with an increased likelihood of having an abnormal nighttime TEMP (OR: 2.79; 95% CI = 1.04-7.53, p = .042). Body mass index was inversely correlated with the likelihood of having abnormal nighttime DBP (OR: 0.37; 95% CI = 0.17-0.79, p = .011). A history of chronic obstructive pulmonary disease (COPD) was inversely correlated with likelihood of having abnormal SBP readings (OR: 0.084; 95% CI = 0.01-0.52, p = .008). Estimated blood loss correlated with abnormal nighttime TEMP (OR: 1.002; 95% CI = 1.001-1.003, p < .001).
Furthermore, daytime abnormalities in vital signs correlated strongly with abnormalities overnight (see Table 4). Compared with patients with a normal daytime HR, patients with an abnormal daytime HR were more likely to have an abnormal nighttime HR (OR: 10.35; 95% CI = 5.84-18.33, p < .001). Abnormal daytime SBP was predictive of abnormal nighttime SBP (OR: 6.23, 95% CI = 3.66-10.60, p < .001), and a similar relationship was found for DBP (OR: 4.31; 95% CI = 2.66-6.98, p < .001). However, abnormal daytime readings of temperature and oxygen saturation were not predictive of abnormal nighttime readings of those particular vital signs.
Discussion
Modern TJA has evolved after decades of incremental improvements in perioperative care, and now most patients can be safely discharged after a short hospital stay or the same day as surgery (Basques et al., 2017; Goyal et al., 2017; Sutton et al., 2016). Within this context, we sought to investigate whether the ritualized practice of awakening patients at night is medically necessary. Although the utility of checking postoperative temperature has been questioned in the past (Ward et al., 2010), to our knowledge this is the first study examining the impact of taking overnight vital signs, a practice that most patients find very disruptive during their early recovery from surgery. We found that the majority of nighttime vitals were within normal ranges from POD 0 through POD 3. When vitals were found to be abnormal, it could be predicted on the basis of medical comorbidities, increased blood loss, and abnormal daytime vital signs. Furthermore, even when nighttime vitals were abnormal, only rarely was there any intervention. This leads to deeper skepticism regarding the utility of this practice.
Sleep hygiene is an underappreciated but critical aspect of recovery following TJA. Transient sleep disturbances are common in the early postoperative period. Prior studies have found these disruptions to persist between 3 and 10 months following TJA (Chen et al., 2016; Manning et al., 2017). Approximately one-third of postsurgical patients respond that sleep reduces pain intensity, three-quarters respond that sleep helps cope with pain, and almost all believe that sleep enhances recovery from surgery (Closs, 1992). Specific to TJA, improved early postoperative sleep has been associated with a greater improvement in quality of life and better satisfaction (Gong et al., 2015). In addition, improved sleep following total knee arthroplasty has been associated with lower pain scores, a lower consumption of antiemetics, and improved range of motion (Gong et al., 2015). Furthermore, patients randomized to extend their preoperative sleep by 2 hours were found to have lower pain scores and utilize less opiates following TJA than those who maintained their normal sleep habits prior to surgery (Roehrs & Roth, 2017). Interventions improving sleep following TJA have improved both sleep patterns (Kirksey et al., 2015) and postoperative pain (Gong et al., 2015).
Reasons for poor sleep during the inpatient stay are multifactorial. Discomfort and pain have a disruptive role. Although postoperative pain has improved with multimodal protocols, side effects from some medications can further disrupt sleep. For example, opioids have been shown to decrease the number and duration of REM periods as well as delay the onset of the first REM period (Cutrufello et al., 2020). Even if patients are able to fall asleep in the hospital, sleep is easily disrupted by the ambient noise level; an investigation of noise levels on inpatient wards showed that the noise levels were higher than recommended standards at all times of day and that the primary sleep inhibitor was the noise from health professionals (Delaney et al., 2018). Intentionally awakening patients one to three times per night to follow a vital sign protocol further exacerbates these factors. Of 166 patients in the hospital setting given a sleep questionnaire, 46% and 34% of patients reported that pain and vital sign measurements, respectively, were the two most disruptive factors to their in-hospital sleep that led to the highest reduction in sleep duration (Grossman et al., 2017).
Data from this study do not support universal cessation of overnight vital sign checks following TJA. A minority of patients had abnormal vital signs at night, and a small percentage of these received overnight interventions from the orthopaedic care team. For instance, one patient in this cohort who underwent an overnight computed tomography angiography for daytime tachycardia that persisted into the overnight period was diagnosed with pulmonary embolism. However, we observed clear correlations between patients with abnormal overnight vital signs and predictive factors such as ASA score, COPD, smoking status, surgical blood loss, and abnormal daytime vital signs. This suggests that the majority of patients who do not meet these criteria could be allowed to sleep undisturbed overnight during their inpatient hospital stay. In addition, our data further support the growing evidence that many TJA patients do not need overnight monitoring in an inpatient setting, further supporting the safety of outpatient or short-stay TJA in which routine vital signs are no longer being recorded. Several studies have shown that rates of readmission, perioperative morbidity, or mortality have not differed in these patients (Berger et al., 2004,2009). Our data further support the notion that not all TJA patients may be ideal candidates for outpatient TJA, as some with specific comorbidities (higher ASA score, COPD, and smoking status) are more likely to demonstrate abnormal postoperative vital signs and thus may benefit from overnight monitoring in a hospital setting.
Given the increasing importance of patient-reported outcomes and patient satisfaction in healthcare systems, it is important for orthopaedic surgeons and nurses to consider the negative implications of our practice patterns, particularly when they are not based in evidence. Although sleep disturbances following TJA are clearly multifactorial, we may be unnecessarily worsening this problem in the vast majority of our patients by waking them for vital sign checks that are not helpful and do not lead to meaningful action being taken. If done in a safe and responsible manner, reducing or eliminating overnight vital sign checks could improve early postoperative outcomes. This practice could also have positive nursing implications as it would allow nurses to give more attention to complex patients with comorbidities.
The role of technology is interesting as it relates to our study. Current technology allows for off-site alarms (e.g., cardiac telemetry), and this type of continuous monitoring may have a role for patients who demonstrate abnormal daytime vitals. Furthermore, for nighttime oxygen saturation, which did not correlate with daytime abnormal values, a similar type of continuous monitoring system could be used with alarms outside of the patient's room. Other newer technologies may address this issue, including wearable watches that connect to apps, and these technologies deserve further consideration as to who might benefit from them, particularly as cost and accessibility to these technologies are quickly improving.
We note several limitations to our methodology. First, we coded abnormal vital sign events in a categorical manner (normal/abnormal/concerning), which gives us limited insight into the predictive value of the severity of abnormal vitals. For example, one recent study examined the ability of abnormal vital signs to predict in-hospital mortality and intensive care unit admission and found that the number of abnormal signs recorded, as well as the magnitude of these changes, were important in predicting in-hospital morbidity and mortality (Barfod et al., 2012). Second, we acknowledge the inherent limitations of our retrospective methodology. Third, the study population represents the experience at a single, urban, university hospital, and it is possible that these observations may not generalize to other practice settings.
Conclusions
Abnormal nighttime vitals following TJA are uncommon, rarely lead to any overnight interventions, and can be predicted on the basis of patient comorbidities and abnormal daytime vital signs. These findings suggest that healthy post-TJA patients with normal daytime vital signs do not need to be woken at night to check vital signs, and nurses can give more attention to complex patients with comorbidities. Modification of postoperative protocols to reflect these findings could potentially allow patients to rest more soundly through the nights following joint replacement, helping them achieve a better postoperative recovery.
References