Decreased heart rate variability responses during early postoperative mobilization--an observational study

Time-course of heart rate variability after total hip arthroplasty

Heart rate variability (HRV) is a measure of the autonomic nervous system function and possibly related to postoperative outcome. Despite several HRV studies in different surgical settings, optimal indices and timepoints for measuring have not been adequately determined. Consequently, there is a need for detailed descriptive procedure-specific studies on the time-course of perioperative HRV within a modern fast-track surgical setting. We measured HRV continuously in 24 patients from 4 days before until 9 days after total hip arthroplasty (THA). Statistical methods included mainly ANOVA and t-tests or Kruskal-Wallis and pairwise Wilcoxon test. Patients completed the Orthostatic Discriminant and Severity Scale five times during the study describing autonomic nervous system dysfunction. Standard deviation between normal-to-normal beats and the total power of HRV were reduced for at least 9 days following THA, with a trend towards increased HRV leading up to the day of surgery. The balance between low- and high-frequency power of HRV was reduced in the postoperative evenings. There was increased orthostatic intolerance symptoms on the first postoperative day, with symptoms of pain, fatigue and weakness decreasing after the first postoperative day. Median hospital stay was 1 day. We provide the first detailed description of perioperative time-course of HRV and orthostatic symptoms in fast-track THA, showing reduced HRV after surgery for at least a week, and that HRV changes are sensitive to time of day and timing before and after surgery. These results are helpful in designing future HRV studies in perioperative risk assessment and outcome.

Orthostatic intolerance after acute mild hypovolemia: incidence, pathophysiologic hemodynamics, and heart-rate variability analysis-a prospective observational cohort study

PURPOSE

Early postoperative mobilization can be hindered by orthostatic intolerance (OI). Postoperative OI has multifactorial pathogenesis, possibly involving both postoperative hypovolemia and autonomic dysfunction. We aimed to investigate the effect of mild acute blood loss from blood donation simulating postoperative hypovolemia, on both autonomic function and OI, thus eliminating confounding perioperative factors such as inflammation, residual anesthesia, pain, and opioids.

METHODS

This prospective observational cohort study included 26 blood donors. Continuous electrocardiogram data were collected during mobilization and night sleep, both before and after blood donation. A Valsalva maneuver and a standardized mobilization procedure were performed immediately before and after blood donation, during which cardiovascular and tissue oxygenation variables were continuously measured by LiDCOrapid™ and Massimo Root™, respectively. The incidence of OI, hemodynamic responses during mobilization and Valsalva maneuver, as well as heart rate variability (HRV) responses during mobilization and sleep were compared before and 15 min after blood donation.

RESULTS

Prior to blood donation, no donors experienced OI during mobilization. After blood donation, 6/26 (23%; 95% CI, 9 to 44) donors experienced at least one OI symptom. Three out of 26 donors (12%; 95% CI, 2 to 30) terminated the mobilization procedure prematurely because of severe OI symptoms. Cardiovascular and cerebral tissue oxygenation responses were reduced in patients with severe OI. After blood loss, HRV indices of total autonomic power remained unchanged but increased sympathetic and decreased parasympathetic outflow was observed during mobilization, but also during sleep, indicating a prolonged autonomic effect of hypovolemia.

CONCLUSION

We describe a specific hypovolemic component of postoperative OI, independent of postoperative autonomic dysfunction, inflammation, opioids, and pain.

STUDY REGISTRATION

ClinicalTrials.gov (NCT04499664); registered 5 August 2020.

Perioperative advanced haemodynamic monitoring of patients undergoing multivisceral debulking surgery: an observational pilot study

BACKGROUND

Patients undergoing high-risk surgery show haemodynamic instability and an increased risk of morbidity. However, most of the available data concentrate on the intraoperative period. This study aims to characterise patients with advanced haemodynamic monitoring throughout the whole perioperative period using electrical cardiometry.

METHODS

In a prospective, observational, monocentric pilot study, electrical cardiometry measurements were obtained using an Osypka ICON™ monitor before surgery, during surgery, and repeatedly throughout the hospital stay for 30 patients with primary ovarian cancer undergoing multivisceral cytoreductive surgery. Severe postoperative complications according to the Clavien-Dindo classification were used as a grouping criterion.

RESULTS

The relative change from the baseline to the first intraoperative timepoint showed a reduced heart rate (HR, median - 19 [25-quartile - 26%; 75-quartile - 10%]%, p < 0.0001), stroke volume index (SVI, - 9.5 [- 15.3; 3.2]%, p = 0.0038), cardiac index (CI, - 24.5 [- 32; - 13]%, p < 0.0001) and index of contractility (- 17.5 [- 35.3; - 0.8]%, p < 0.0001). Throughout the perioperative course, patients had intraoperatively a reduced HR and CI (both p < 0.0001) and postoperatively an increased HR (p < 0.0001) and CI (p = 0.016), whereas SVI was unchanged. Thoracic fluid volume increased continuously versus preoperative values and did not normalise up to the day of discharge. Patients having postoperative complications showed a lower index of contractility (p = 0.0435) and a higher systolic time ratio (p = 0.0008) over the perioperative course in comparison to patients without complications, whereas the CI (p = 0.3337) was comparable between groups. One patient had to be excluded from data analysis for not receiving the planned surgery.

CONCLUSIONS

Substantial decreases in HR, SVI, CI, and index of contractility occurred from the day before surgery to the first intraoperative timepoint. HR and CI were altered throughout the perioperative course. Patients with postoperative complications differed from patients without complications in the markers of cardiac function, a lower index of contractility and a lower SVI. The analyses of trends over the whole perioperative time course by using non-invasive technologies like EC seem to be useful to identify patients with altered haemodynamic parameters and therefore at an increased risk for postoperative complications after major surgery.

Steroids Significantly Decrease Postoperative Postural Hypotension in Total Knee Replacement

Total knee replacement (TKR) is one of the most common orthopaedic procedures performed, and enhanced recovery after surgery (ERAS) has been developed and incorporated into inpatient surgical pathways to improve patient outcomes. Under ERAS recommendations, multimodal prophylaxis has been used to help manage postoperative nausea and vomiting (PONV) following TKR. Dexamethasone is one of the commonly used for this and the anti-inflammatory properties could depress vagal activity, reducing postural hypotension (PH). The hypothesis of this study is that postoperative dexamethasone use is associated with lower rates of early postoperative PH following TKR surgery. In our institution, patients who undergo elective primary TKR are admitted on the day of surgery and follow a standardized ERAS protocol. Data on patients who underwent elective primary TKR under a single adult reconstruction team from September 2017 to March 2020 were reviewed and analyzed. A review of demographic characteristics, surgical data, postoperative medications, and postoperative notes was performed. Binary logistic regression was used to assess the effect of the use of dexamethasone on PH, with an adjusted odds ratio (OR) calculated after accounting for potential confounders. Of the 149 patients were included in the study, 78 had dexamethasone postoperatively, and 71 did not. Patients who had received dexamethasone were statistically less likely to suffer from PH (OR = 0.31, p = 0.03) and less likely to develop PONV (OR = 0.21, p = 0.006). Patients who had received dexamethasone were more likely able to participate in early physiotherapy (OR = 2.42, p = 0.14), and this result was statistically insignificant. The use of postoperative intravenous dexamethasone is significantly associated with lower rates of postoperative PH after TKR. However, more studies are required to assess the optimal dosing amount and frequency, as well as to assess other factors which can enhance early postoperative patient mobilization as part of our goals for ERAS. This therapeutic study reflects level of evidence III.

Effect of using elastic-pressure socks in spinal surgery patients on orthostatic hypotension in the first mobilization

BACKGROUND

Orthostatic hypotension (OH) is a common early postoperative finding in patients who undergo major surgery, and it might delay early mobilization, which is the main building block of modern perioperative care programs. The aim of this study was to determine the effect of using thigh-length elastic pressure socks in patients who undergo spinal surgery in development of OH at first mobilization after surgery.

METHODS

The study was a randomized-controlled intervention study. A total of 70 patients who underwent spinal surgery were included in the study. The patients were allocated randomly to the intervention group (n = 35) who used thigh-length elastic pressure socks and the control group (n = 35) which received no intervention other than routine nursing care.

RESULTS

It was found in the study that 2.9% of the patients in the intervention group developed OH during the first mobilization after the surgery, and 48.6% of the patients in the control group developed OH at first mobilization. The patients in the intervention group were found to have the risk ratio (RR): 0.06 times less probability of developing OH than the patients in the control group (95% confidence interval [CI]:0.01-0.42). The OH symptoms were lower in the patients in the intervention group.

CONCLUSION

It was found as a result of the study that using thigh-length elastic pressure socks in spinal surgery patients reduced OH development and symptoms at first mobilization after the surgery.

Precision implementation of early ambulation in elderly patients undergoing off-pump coronary artery bypass graft surgery: a randomized-controlled clinical trial

Background

Although early ambulation (EA) is associated with improved outcomes in post-operative patients, implementation of EA in elderly patients is still a challenge. In this study, we aimed to design and assess a precision early ambulation program for cardiac rehabilitation.

Methods

We conducted a single-center, randomized and controlled clinical trial in elderly patients aged over 60 years after off-pump coronary artery bypass graft (OPCABG) surgery. Patients were randomly assigned to a precision early ambulation (PEA) group or a routine ambulation (Control) group. Age-predicted maximal heart rate (APMHR) and maximal oxygen uptake (VO_2max) were used as a reference to formulate and monitor the PEA regimen. The primary end-point was the postoperative length of stay in hospital (PLOS). The secondary end-points included 90-day mortality, incidence of early discharge, laboratory tests, length of ICU stay, the incidence of multiple organ complications and post-traumatic stress disorder (PTSD). Ambulation outcomes were also recorded.

Results

In total, 178 patients were enrolled (n = 89 per group). In the intent-to-treat analysis, PLOS in the PEA group was shorter than that in the Control group (9.04 ± 3.08 versus 10.09 ± 3.32 days, respectively. Mean difference 1.045 days; 95% confidence interval [CI] 0.098–1.992; P = 0.031 in the unadjusted model; mean difference 0.957 days; CI 0.007–1.907; P = 0.048 in adjusted model). The incidence of early discharge differed significantly between the PEA and control groups (41[46.1%] versus 24[27.0%] patients, respectively. Odds ratio [OR] 0.432; CI 0.231–0.809; P = 0.009 in unadjusted model; OR 0.466; CI 0.244–0.889, P = 0.02 in adjusted model). The time of first bowel movement, partial pressure O₂ and post-traumatic stress disorder score in the PEA group were better than those in the Control group. Participants walked much longer distances on day 3 in the PEA group than those in the Control group (76.12 ± 29.02 versus 56.80 ± 24.40 m, respectively, P < 0.001).

Conclusion

APMHR and VO_2max are valuable for implementation of PEA according to an established security threshold. PEA after OPCAPG surgery is safe and reliable for elderly patients, not only reducing the hospital stay, but also improving their physiological and psychological symptoms.

Trial registration

This study is a component of a protocol retrospectively registered: Application of ERAS in cardiovascular surgery. Trial registration number: ChiCTR1800018167. Date of registration: 3rd September, 2018. URL of trial registry record: http://www.chictr.org.cn/index.aspx

Changes in the augmentation index and postoperative orthostatic intolerance in orthopedic surgery: a prospective cohort study

BACKGROUND

Postoperative orthostatic intolerance (OI) can be a major obstacle to early ambulation and its determinants are poorly understood. We aimed to study postoperative changes in vascular tone and their potential association with OI in various orthopedic surgical settings.

METHODS

In this prospective cohort study, 350 patients undergoing total joint arthroplasty under neuraxial anesthesia or spine surgery under general anesthesia were enrolled. We determined the augmentation index (AI) as a measure of vascular tone and studied symptoms of OI using a validated questionnaire at various postoperative time points.

RESULTS

The AI was significantly reduced postoperatively (at spinal resolution in patients with neuraxial anesthesia or two hours postoperatively in general anesthesia) compared with baseline values in all procedures and did not subsequently return to baseline throughout the postoperative period in the majority of patients [252/335 (75.2%); P < 0.001]. The majority [260/342 (76.0%); P < 0.001] of patients had postoperative symptoms of OI. Nevertheless, no association was found between postoperative change in AI from baseline and postoperative symptoms of OI.

CONCLUSIONS

A significantly prolonged decrease in AI and symptoms of OI are common after orthopedic surgery. Nevertheless, an association between the two measures was not observed. While compensatory mechanisms may limit the influence of an AI decrease on symptoms of OI, more research is needed to understand the contributing factors and aid in the identification of patients at risk of OI.

Incidence of orthostatic hypotension and cardiovascular response to postoperative early mobilization in patients undergoing cardiothoracic and abdominal surgery

BACKGROUND

In cardiothoracic and abdominal surgery, postoperative complications remain major clinical problems. Early mobilization has been widely practiced and is an important component in preventing complications, including orthostatic hypotension (OH) during postoperative management. We investigated cardiovascular response during early mobilization and the incidence of OH after cardiothoracic and abdominal surgery.

METHODS

In this prospective observational study, we consecutively analyzed data from 495 patients who underwent elective cardiothoracic and abdominal surgery. We examined the incidence of OH, and the independent risk factors associated with OH during early mobilization after major surgery. Multivariate logistic regression was performed using various characteristics of patients to identify OH-related independent factors.

RESULTS

OH was observed in 191 (39%) of 495 patients. The incidence of OH in cardiac, thoracic, and abdominal groups was 39 (33%) of 119, 95 (46%) of 208, and 57 (34%) of 168 patients, respectively. Male sex (OR 1.538; p = 0.03) and epidural anesthesia (OR 2.906; p < 0.001) were independently associated with OH on multivariate analysis.

CONCLUSIONS

These results demonstrate that approximately 40% patients experience OH during early mobilization after cardiothoracic and abdominal surgery. Sex was identified as an independent factor for OH during early mobilization after all three types of surgeries, while epidural anesthesia was only identified after thoracic surgery. Therefore, the frequent occurrence of OH during postoperative early mobilization should be recognized.

TRIAL REGISTRATION

University hospital Medical Information Network Center (UMIN-CTR) number UMIN000018632 . (Registered on 1st October, 2008).