Postoperative Incidence of Orthostatic Intolerance and Hypotension in Primary Unicompartmental Knee Arthroplasty (UKA)

Study Overview
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Brief Summary
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Incidence and pathophysiologic hemodynamics of orthostatic intolerance and orthostatic hypotension in patients undergoing UKA

Detailed Description
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In today's multimodal fast-track perioperative care program (ERAS) early mobilization is an essential cornerstone, and is known to prevent postoperative morbidity and lower length of stay in the hospital. Intact orthostatic blood pressure regulation is necessary to complete mobilization, and postoperative orthostatic hypotension (OH), defined as a drop in systolic arterial pressure (SAP) > 20 mmHg or a drop >10 mmHg in diastolic arterial pressure (DAP) and orthostatic intolerance (OI), characterized by dizziness, nausea, feeling warm and syncope related to orthostatic challenge, are well-known reasons for delayed early mobilization, prolonged bedrest and delayed ambulation. Former studies have been accessing the postoperative incidence in THA-patients (22%-40%), TKA-patients(36%), colorectal patients(53%), abdominal and cardiothoracic surgery patients(40%), radical prostatectomy patients (50%). One study have been accessing the postoperative incidence of OI in mastectomy patients and found an incidence of 4%, and thereby indicating that postoperative OI is not an issue in minor surgery. This study is the first, to our acknowledgement, which accesses the postoperative incidence of OI/OH in UKA-patients.

Official Title
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Postoperative Incidence of Orthostatic Intolerance and Hypotension in Patients Undergoing Primary Unicompartmental Knee Arthroplasty (UKA)

Conditions
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Orthostatic Hypotension, Orthostatic Intolerance, Postoperative Complications

Intervention / Treatment
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* Other: Standardized mobilization procedure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age >18 years and Patients undergoing UKA in spinal anesthesia at Hvidovre Hospital in a standardized fast-track setting. Patients that speak and understand Danish Written informed consent Exclusion Criteria: Pre-existing orthostatic hypotension or intolerance Alcohol or substance abuse everyday treatment with either anxiolytic or antipsychotic medicine Cognitive dysfunction If surgery was converted to general anesthesia or total knee arthroplasty.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Orthostatic intolerant (OI)<br>Patients that experience symptoms of orthostatic intolerance (dizziness, nausea, vomiting, blurry vision or syncope) or orthostatic hypotension (fall in systolic pressure > 20 mmHg and/or diastolic pressure > 10 mmHg) during mobilization | Other: Standardized mobilization procedure<br>* 5 minutes bed rest (h1), followed by 3 minutes passive leg raise (PLR), followed by 5 minutes bed rest (h2), followed by 3 minutes sitting on the egde of the bed (sit), followed by 3 minutes standing/walking on the spot (sta), followed by 5 minutes bedrest (h3)<br>|
| Orthostatic tolerant (OT)<br>Patients that do not experience symptoms of orthostatic intolerance (dizziness, nausea, vomiting, blurry vision or syncope) or orthostatic hypotension (fall in systolic pressure > 20 mmHg and/or diastolic pressure > 10 mmHg) during mobilization | Other: Standardized mobilization procedure<br>* 5 minutes bed rest (h1), followed by 3 minutes passive leg raise (PLR), followed by 5 minutes bed rest (h2), followed by 3 minutes sitting on the egde of the bed (sit), followed by 3 minutes standing/walking on the spot (sta), followed by 5 minutes bedrest (h3)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of orthostatic intolerance | Symptoms of orthostatic intolerance: dizziness, nausea, vomiting, blurry vision or syncope during mobilization | 6 hours postoperatively | 
| Incidence of orthostatic hypotension | Orthostatic hypotension is defined as a fall in systolic pressure > 20 mmHg and/or diastolic pressure > 10 mmHg during mobilization | 6 hours postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in systolic arterial pressure (SAP) during mobilization | Measured in mmHg, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in diastolic arterial pressure (DAP) during mobilization | Measured in mmHg, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in mean arterial pressure (MAP) during mobilization | Measured in mmHg, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in cardiac output (CO) during mobilization | Measured in mL/min, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in systemic vascular resistance (SVR) during mobilization | Measured in mmHg⋅min⋅mL-1 | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in stroke volume (SV) during mobilization | Measured in mL, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in heart rate variability (HRV) during mobilization | Measured in ms, LiDCO-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in peripheral perfusion index (PPI) during mobilization | Measured in arbitrary units (AU), Massimo apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in cerebral perfusion (ScO2) during mobilization | Measured in %, NIRS-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in muscular perfusion (SmO2) during mobilization | Measured in %, NIRS-apparatus | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in haemoglobin (Hgb) concentration | Measured in millimoles/L | Preoperatively, 6 and 24 hours postoperatively | 
| Changes in C-Reactive Protein | Measured in mg/L | Preoperatively, 6 and 24 hours postoperatively |