Assessing the Efficacy of Intravenous Acetaminophen Versus the Oral Formulation for Perioperative Pain Treatment

Study Overview
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Brief Summary
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To compare oral (PO) to intravenous (IV) acetaminophen with postoperative pain scores, and consumptions of opiates, among orthopedic surgery patients undergoing total knee replacement with spinal anesthesia. Our hypothesis is that IV acetaminophen patients will have improved analgesia, less opioid consumption, a lower percentage of patients rescuing, or a longer time to first rescue with IV acetaminophen. The investigators will compare the efficacies of oral and intravenous acetaminophen for postoperative pain control, and utilization of opiates as rescue agents.

Detailed Description
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Intravenous acetaminophen has rapid onset and potent analgesic properties. Recent studies have shown several advantages of using intravenous acetaminophen perioperatively. However, due to its relatively high cost and limited clinical data concerning its efficacy compared with other agents, physicians are hesitant to use intravenous acetaminophen in the perioperative period. 174 adult patients from the orthopedic surgeons undergoing total knee replacement with spinal anesthesia will be enrolled. The study will be double blind, randomized; placebo controlled comparing oral and IV acetaminophen to each other and a control (placebo). At the time patients arrive in the post-anesthesia care unit (PACU), Group 1 will receive IV 1 gram acetaminophen, and PO placebo; Group 2 will receive PO 1 gram acetaminophen and IV placebo; Group 3 will receive IV placebo and PO placebo. The primary outcome that will be assessed is pain scores, which will be recorded by using the numeric rating scale 1-10 every 15 minutes. Secondary outcomes include time to rescue analgesia (measured in minutes), time to PACU discharge (measured in minutes), and the total amount of hydromorphone (PO or IV) consumed within 6 hours postoperatively for adequate analgesia (total measured in milligrams) will be collected. The difference in pain scores will be assessed by a chi-square test. A multivariable regression model will be performed with the clinical and statistically significant variables to remove confounding.

Official Title
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Assessing the Efficacy of Intravenous Acetaminophen Versus the Oral Formulation for Perioperative Pain Treatment

Conditions
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Postoperative Pain

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients undergoing total knee replacement Successful spinal placement ≥18 years old Exclusion Criteria: Failed spinal anesthesia Chronic opiate users Liver disease patients Allergy/hypersensitivity to acetaminophen Patients with baseline dementia Patients weighing less than 50kg, history of alcohol dependence, renal impairment, opiate allergy, and pregnancy.

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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain scores assessed and recorded by using the numeric rating scale | The primary outcome that will be assessed is pain scores, which will be recorded by using the numeric rating scale, from 1-10, every 15 minutes. | Participants will be followed for the duration of their inpatient hosptial stay, an expected average of one week. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to rescue analgesia | The amount of time after the surgery is completed until a patient receives rescue analgesia will be measured in minutes. | Participants will be followed for the duration of their hospital stay, an expected average of one week | 
| Time to post-anesthesia care unit (PACU) discharge | The time from arrive in the PACU to discharge will be measured in minutes. | Participants will be followed for the duration of their PACU stay, an expected average of 5 hours. | 
| Opioid Use | The investigators will collect total amount of oral and/ or intravenous hydromorphone that is consumed by for adequate analgesia. | Participants will be followed for six hours postoperatively. | 
| Postoperative nausea and vomiting | The investigators will collect information on postoperative nausea and vomiting. | Participants will be followed for six hours postoperatively. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acetaminophen, Total knee replacement, Numeric rating scale