Comparison of Outcomes When Patients Receive Preoperative IV Acetaminophen Versus Preoperative Oral Acetaminophen
Phase: PHASE4
Conditions: Pain, Postoperative
Sponsor: TriHealth Inc.

IV vs PO Acetaminophen Preoperatively     1 
 
RESEARCH PROTOCOL 
 
Date 
3/1/2018 
Title 
Comparison of Outcomes when Patients Receive Preoperative IV 
Acetaminophen versus Preoperative Oral Acetaminophen  
Principal Investigator 
Diana Pelzer, BSN, RN, CAPA 
Sub-Investigators 
Jennifer Cox, BSN, RN; Elizabeth Burgess, MD 
Research Specialist 
Rachel Baker, PhD, RN 
Department 
Bethesda Butler, Perioperative Services 
Hatton # 
17-114 
 
Purpose of Study    
 
In the fall of 2016, there was a change implemented in the clinical care of patients undergoing 
surgery at Bethesda Butler. Previously, intravenous Acetaminophen was routinely ordered for 
surgical patients and administered preoperatively, either by the RN, or by anesthesia personnel 
prior to the surgical incision.  A system-wide change occurred, and routine use of preoperative 
intravenous Acetaminophen ceased; instead, patients were given oral Acetaminophen prior to 
surgery.  Anecdotally, recovery room nurses at Butler have noticed negative patient outcomes 
after this change in care was implemented.  An extensive literature search was undertaken, and 
no research was found that compared the different administration routes of Acetaminophen in 
surgical patients.  The current study proposes to fill this gap in the literature, and examine the 
trend that nurses have experienced during clinical care, to determine if there is a significant 
difference in outcomes related to the administration route of preoperative Acetaminophen. 
Specifically, the study will compare the following outcomes of surgical patients who receive IV 
Acetaminophen with surgical patients who receive oral Acetaminophen: postoperative pain, 
postoperative opioid dose, postoperative nausea and vomiting, length of stay in recovery room, 
and patient satisfaction with pain control. Ultimately, we would plan to use the results of this 
study to advocate for best preoperative care for patients to improve patient outcomes and 
experience with care.  
 
Hypotheses or Research Questions 
 
Hypothesis 1:  Patients who received IV Acetaminophen preoperatively will report decreased 
pain in the PACU compared to patients who received oral Acetaminophen preoperatively. 
 
Hypothesis 2:  Patients who received IV Acetaminophen preoperatively will receive decreased 
opioid doses compared to patients who received oral Acetaminophen preoperatively. 
 
Hypothesis 3:  Patients who received IV Acetaminophen preoperatively will experience less 
negative effects of pain medications (including postoperative nausea and vomiting, respiratory 
depression, and need for reversal agents) compared to patients who received oral 
Acetaminophen preoperatively. 

IV vs PO Acetaminophen Preoperatively     2 
 
 
Hypothesis 4:  Surgery patients who received IV Acetaminophen preoperatively will have a 
shorter length of stay in the recovery room compared to surgical patients who received oral 
Acetaminophen preoperatively. 
 
Hypothesis 5:  Surgery patients who received IV Acetaminophen preoperatively will report 
higher satisfaction with their pain control compared to surgical patients who received oral 
Acetaminophen preoperatively. 
 
Background  
 
Anecdotally, nurses noticed negative patient outcomes after a change in care was implemented 
from patients receiving Acetaminophen intravenously preoperatively to patients receiving 
Acetaminophen orally before surgery.  To assess clinical care before and after this practice 
change, a template was created through coordination with an assigned Lead Applications 
Programming Analyst from the Information Technology Department to pull retrospective data 
at Bethesda Butler.  An Epic report was generated to examine outcomes of surgical patients 
before and after the change in practice (no patient identifiers were included).  The report, 
completed at the end of June, 2017, contained information mined from Epic from 2016, and 
included over 2000 surgical patients who had surgical procedures under general anesthesia, 
and received either IV or oral Acetaminophen.  However, we were unable to draw conclusions 
based on this data because of missing documentation and variations in documentation; more 
than one third of the data (885/2609, or 34%) had to be thrown out.  Additionally, the actual 
amount of opioids given (total mg or mcg) was not discoverable.   
 
To determine whether there was evidence around this practice change, a literature search was 
also completed.  Several studies examined the relationship between giving IV Acetaminophen 
preoperatively, compared to not administering IV Acetaminophen (or administering a placebo), 
and found benefits including a reduction in reported pain (McNicol et al., 2011; Salihoglu et al., 
2009), a reduction in postoperative opioid consumption (Jebaraj et al., 2013; Maund et al., 
2011; McNicol et al., 2011; Moon et al., 2011; Remy, Marret, and Bonnet, 2005; Salihoglu et al., 
2009; Song, Melroy, & Whipple, 2014), a reduction in postoperative nausea and vomiting (Song, 
Melroy, & Whipple, 2014), a reduction in length of stay (Hansen et al., 2016; Song, Melroy, & 
Whipple, 2014), and a reduction in hospitalization costs (Hansen et al., 2016).  These studies 
report important benefits to patients receiving IV Acetaminophen preoperatively compared to 
not receiving Acetaminophen at all.  However, the debate is not whether to administer IV 
Acetaminophen or no Acetaminophen.  Oral Acetaminophen is currently being administered in 
an attempt to achieve the same outcomes that have been shown after IV Acetaminophen 
administration.  This translation from research supporting IV Acetaminophen administration to 
clinically administering oral Acetaminophen is not evidence-based.  To date, there have been 
no studies evaluating the use of oral Acetaminophen to achieve these same outcomes, and   
no studies comparing the effect of patients receiving IV Acetaminophen to oral Acetaminophen 
preoperatively.  Experts in the field have called for randomized studies that take the current 
evidence a step further and compare the route of Acetaminophen administration 

IV vs PO Acetaminophen Preoperatively     3 
 
preoperatively (Boggs, 2017).  The current study proposes to address this gap in the literature 
by determining if there is a significant difference in patient outcomes related to the 
administration route of preoperative Acetaminophen (IV vs oral). Specifically, the study will 
compare the following outcomes of surgical patients who receive preoperative IV 
Acetaminophen with surgical patients who receive preoperative oral Acetaminophen: 
postoperative pain, post-operative opioid dose, postoperative nausea and vomiting, length of 
stay in recovery room, and patient satisfaction with pain control.  
 
Research Plan  
 
Study Design 
 
This study will use a randomized, double-blind, controlled design with two arms:  
Arm 1: Scheduled IV Acetaminophen provided preoperatively 
Arm 2: Scheduled PO Acetaminophen provided preoperatively   
 
 
Setting for the study 
 
This study will take place at Bethesda Butler Hospital in the perioperative department.  This unit 
consists of 12 preoperative bays, 8 operating rooms, and 9 postoperative recovery bays.  The 
department provides care for patients undergoing procedures including (but not limited to) 
arthroscopy, ear/nose/throat, gynecology, laparoscopy, ophthalmology, orthopedic total joint 
replacement, plastics, and podiatry. 
 
Before the study begins, the study staff will provide education to all of the nurses working in 
the perioperative department involved in patient care.  This education will include information 
about the study design, the intervention, the inclusion/exclusion criteria, and the data 
collection forms. Letter to Patients will be provided to surgeons to hand out to their patients 
during the pre-surgical visit. Additionally, the presurgical services staff who call the patients 
before surgery will be provided a script to read describing the study. Both the letter and the 
phone script will be used to provide information about the study to patients, but will not be 
used to determine eligibility or consent. By offering information about the study before the day 
of surgery, we are hoping to decrease the anxiety involved when study staff approach the 
patients the morning of surgery. 
 
Participants 
 
This study will enroll patients who meet the inclusion/exclusion criteria and who consent to the 
study. 
 
Inclusion criteria: 
• 18 years old or older 

IV vs PO Acetaminophen Preoperatively     4 
 
• Admitted to Bethesda Butler Main Perioperative Services for an outpatient surgical 
procedure performed under general anesthesia 
 
Exclusion criteria:  
• Allergy to Acetaminophen 
• Lactose intolerance or lactose allergy (placebo capsules contain lactose) 
• Hepatic disease 
• Having taken a product containing acetaminophen within 6 hours of scheduled surgery 
time 
• Pregnant 
• Weight less than 60kg 
• Opioid addiction – admits to current opioid addiction and/or substance abuse disorder, 
and/or currently in treatment for opioid addiction or substance abuse 
• Emergent or on-call procedures 
• Inpatient surgery 
 
Each day, the study staff will review the patients scheduled for surgery to determine potential 
subjects.  In addition, the study staff expects that the staff education provided before 
implementation of the research study may result in clinical nurses notifying study staff when an 
eligible patient is identified.  By reviewing daily census and involving the clinical staff in 
identifying potential subjects, the study staff hopes to approach the majority of the potentially 
eligible patients.  When a patient appears to be eligible, study staff will complete the 
Inclusion/Exclusion Criteria Checklist.  If the patient is eligible, a study staff member will meet 
with the patient and describe the study and answer any questions.  If the patient is interested 
in enrolling in the study, the study staff will review the Informed Consent Form and HIPAA form 
and obtain written informed consent.  Patients will receive a copy of their signed Informed 
Consent form and HIPAA form.  
 
Sample Size Determination:  No studies were found examining the impact of IV versus oral 
Acetaminophen on the listed dependent variables.  Therefore, a power analysis was conducted 
using G*Power (version 3.1.9.2) with a default medium effect size (0.5), power of 0.8, and level 
of significance 0.05.  It was determined that 53 patients would be needed in each group, for a 
total sample size of 106 patients.  We plan to enroll 120 patients (60 patients in each group) to 
allow for any missing data or withdrawals.  Additionally, 120 patients will provide adequate 
power to detect a clinically significant (2 point difference on a 0-10 pain rating scale) mean 
difference in pain scores between two groups.  
 
Procedures 
 
Randomization:  
After obtaining informed consent, the subject will be randomized into one of two groups:  
1. IV Acetaminophen 
2. Oral Acetaminophen 

IV vs PO Acetaminophen Preoperatively     5 
 
 
To randomize the subject, the study staff will assign the patient the next study ID number on a 
list.  The pharmacy will have a list of subject ID numbers with corresponding randomization 
assignments.  This list will be created from a computerized simple random number generator 
(1:1 randomization) prior to the start of the study.  Only the pharmacists will have access to this 
information. 
 
The Study ID number will be added to the top of the Data Collection Form. Study staff will add 
the patient’s name to the Enrollment Log that connects the subject ID number to the patient’s 
name.  This is the only list that will connect patient identifiers to study ID numbers.  Beginning 
with selection of the envelope, all documents will be labeled with only subject ID number and 
no patient identifiers. 
 
Intervention or experimental aspect of the study 
 
Once the patient has been randomized, the nurse will provide study ID number to the 
pharmacist who will provide the correct IV and oral medications:   
• Patients randomized to Arm 1 (IV Acetaminophen group) will receive IV Acetaminophen 
1000mg in 100mL once and a PO placebo pill preoperatively 
• Patients randomized to Arm 2 (Oral Acetaminophen group) will receive IV saline 100mL 
once and Acetaminophen 1000 mg PO once preoperatively  
Patients and nurses will be blinded about which of the IV solution and capsule is active and 
which is a placebo.  The pharmacists will have access to the randomization scheme and will be 
able to unblind medication administration in case the information is needed for clinical care.  
 
Patients in both arms of the study will receive standard postoperative care including 
assessment and management of postoperative pain.  All care received, except route of 
preoperative Acetaminophen, will follow standard of care.  
 
Data Collection 
The following variables will be collected:  
• Independent variable:  
o Route of Acetaminophen administration (IV or oral)  
• Dependent variable:  
o Postoperative pain score – patient’s self-report of pain using a 0-10 pain scale as 
documented by clinical nurse in the patient’s electronic medical record 
o Amount of postoperative opioid pain medication administered – this will be 
documented by clinical nurse in the patient’s electronic medical record when 
administered 
o Postoperative nausea and vomiting – As documented by the clinical nurse in the 
patient’s electronic medical record 
o Occurrence of respiratory depression – As documented by low O2 saturation in 
the patient’s electronic medical record 

IV vs PO Acetaminophen Preoperatively     6 
 
o Administration of reversal agent – As documented by the clinical nurse in the 
patient’s electronic medical record 
o Length of stay in recovery room – Duration of length of stay in PACU is routinely 
recorded on all patients’ electronic medical record (this will include both Phase I, 
and Phase II when applicable) 
o Patient satisfaction with pain control – This question will be asked of patients 
during the post-operative telephone call, which generally takes place 1 day (3 
days if the procedure is performed on Friday) after surgery.  The patients will be 
asked:  On a scale of 1-10 (with 1 being extremely dissatisfied and 10 being 
extremely satisfied), how satisfied were you with your pain control on the day of 
surgery?   
• Potentially confounding variables:  These variables are routinely documented in 
patients’ electronic medical record.  The study team will record this data from the 
medical records.   
o Age 
o Gender 
o Weight 
o Medications 
o Type of surgery 
o Length of surgery 
o Baseline pre-operative pain level 
o Postoperative nausea and vomiting risk score 
o Prophylactic anti-emetic administered 
o Nerve block given 
o Local medication injected 
o Additional preoperative medications given (ie. Celebrex, Oxycontin, Neurontin) 
for pain management 
 
Each day, the study team members will review the Enrollment Log from the previous day and 
the study team nurses will make the clinical postoperative discharge telephone calls for 
patients were enrolled in the study.  The telephone call will follow the standard script used 
clinically for all patients and then one additional question will be asked at the end of the call: 
On a scale of 1-10 (with 1 being extremely dissatisfied and 10 being extremely satisfied), how 
satisfied were you with your pain control on the day of surgery?  The patient’s response to this 
question will be recorded on the Enrollment Log.  
 
To collect the remaining outcome data, a paper data collection form will be placed on the 
patient’s chart.  The RN caring for the patient post-operatively will be asked to complete the 
form at the time of patient care.  The form includes: Times of Acetaminophen/Placebo (IV and 
oral) administration, postoperative pain scores (before and after pain medication 
administration), opioid medications administered (including cumulative dose of each 
medication administered), any occurrence of postoperative nausea, any occurrence of 
postoperative vomiting, any low O2 saturations (<92%), and any reversal medications 
administered.  The study team will conduct a review of the medical records of all patients 

IV vs PO Acetaminophen Preoperatively     7 
 
enrolled in the study and complete the following information on the data collection sheet:  
Time surgery started, time surgery ended, time into recovery room and time discharged from 
recovery room (includes Phase I, and Phase II when applicable), age, gender, weight, type of 
surgery, baseline preoperative pain score, postoperative nausea and vomiting risk score, 
prophylactic anti-emetics administered, preoperative nerve block given, any local injected, 
additional preoperative medications given for pain management.  
 
Additionally, any adverse events experienced by patients will be documented and 
communicated to the patient’s clinical team.  The pharmacist(s) will be able to unblind 
Acetaminophen route administration if needed for clinical care of the patient.  All adverse 
events will be reviewed by the study team and reported to the Institution Review Board (IRB) 
following IRB guidelines. 
 
Statistical Analysis 
 
Data will be recorded on paper data collection forms with only subject ID and no identifiers. 
Data from these forms will be entered into a password protected database.  Only study team 
members will have access to the database. No personal information will be entered into the 
electronic database.  Data will undergo range checks when entered into the database, and 
quality control procedures will be performed to ensure accuracy of the data in the electronic 
database.  
 
Statistical analyses will be performed using SPSS statistical software.  Descriptive statistics 
(frequencies for categorical data; means and standard deviations and ranges for continuous 
data) will be used to describe the sample.  The following analyses will be performed to address 
each hypothesis: 
 
Hypothesis 1:  Patients who received IV Acetaminophen preoperatively will report decreased 
pain in the PACU compared to patients who received oral Acetaminophen preoperatively. 
To compare the effects of the intervention, a Mann-Whitney U test will be used to 
compare mean pain scores for patients who received IV Acetaminophen to the mean 
pain scores of patients who receive oral Acetaminophen.  A level of significance of 
α=0.05 will be used.  Secondary analyses will be planned using multiple regression 
modelling to adjust for the potential confounding variables.  
 
Hypothesis 2:  Patients who received IV Acetaminophen preoperatively will receive decreased 
opioid doses compared to patients who received oral Acetaminophen preoperatively. 
To compare the effects of the intervention, an independent samples t-test will be used to 
compare mean dose of opioids received for patients who received IV Acetaminophen to 
the mean dose of opioids received among patients who receive oral Acetaminophen.  A 
level of significance of α=0.05 will be used. Secondary analyses will be planned using 
multiple regression modelling to adjust for the potential confounding variables.  
 

IV vs PO Acetaminophen Preoperatively     8 
 
Hypothesis 3:  Patients who received IV Acetaminophen preoperatively will experience less 
negative effects of pain medications (including postoperative nausea and vomiting, respiratory 
depression, and need for reversal agents) compared to patients who received oral 
Acetaminophen preoperatively. 
To compare the effects of the intervention, a Chi Square test will be used to compare 
occurrence of postoperative nausea and vomiting for patients who received IV 
Acetaminophen to patients who receive oral Acetaminophen.  A level of significance of 
α=0.05 will be used.  Secondary analyses will be planned using multiple regression 
modelling to adjust for the potential confounding variables. 
 
To compare the effects of the intervention, a Chi Square test will be used to compare 
occurrence of postoperative respiratory depression for patients who received IV 
Acetaminophen to patients who receive oral Acetaminophen.  A level of significance of 
α=0.05 will be used.  Secondary analyses will be planned using multiple regression 
modelling to adjust for the potential confounding variables. 
 
To compare the effects of the intervention, a Chi Square test will be used to compare 
occurrence of administration of reversal agents for patients who received IV 
Acetaminophen to patients who receive oral Acetaminophen.  A level of significance of 
α=0.05 will be used.  Secondary analyses will be planned using multiple regression 
modelling to adjust for the potential confounding variables. 
 
Hypothesis 4:  Surgery patients who received IV Acetaminophen preoperatively will have a 
shorter length of stay in the recovery room compared to surgical patients who received oral 
Acetaminophen preoperatively. 
To compare the effects of the intervention, an independent samples t-test will be used to 
compare mean length of PACU stay for patients who received IV Acetaminophen to the 
mean length of PACU stay for patients who receive oral Acetaminophen.  A level of 
significance of α=0.05 will be used.  Secondary analyses will be planned using multiple 
regression modelling to adjust for the potential confounding variables.  
 
Hypothesis 5:  Surgery patients who received IV Acetaminophen preoperatively will report 
higher satisfaction with their pain control compared to surgical patients who received oral 
Acetaminophen preoperatively. 
To compare the effects of the intervention, a Mann-Whitney U test will be used to 
compare mean satisfaction rating for patients who received IV Acetaminophen to the 
mean satisfaction rating of patients who receive oral Acetaminophen.  A level of 
significance of α=0.05 will be used.  Secondary analyses will be planned using multiple 
regression modelling to adjust for the potential confounding variables.  
 
 
 
Ethical Considerations 
 

IV vs PO Acetaminophen Preoperatively     9 
 
Informed consent 
 
All study staff will complete CITI training.  A study staff member will meet with potentially 
eligible patients and describe the study and answer any questions.  If the patient is interested 
and meets all the inclusion/exclusion criteria, the study staff will review the Informed Consent 
Form and HIPAA form and obtain written informed consent.  Patients will receive a copy of their 
signed Informed Consent form and HIPAA form.  
 
Informed Consent forms and HIPAA forms will be stored in a locked cabinet that only study staff 
will have access to.  After the study closes, the signed Informed Consent forms and HIPAA forms 
will be boxed and sent to off-site storage and securely stored for 10 years.  At that time, the 
hard copy forms will be shredded.  
 
Privacy information 
 
Personal identifiers will be recorded on the Informed Consent, on the HIPAA forms, and on the 
Enrollment Log.  All other data collection forms and electronic database of final data will 
include study ID number only.  
 
Hard copy forms (including Informed Consent forms, HIPAA forms, and data collection sheets) 
will be stored in locked cabinets that only study staff will have access to.  Electronic data 
(including Enrollment Log and data entered into an electronic database) will be stored on a 
password-protected folder on the U drive.  Only study staff will have access to the electronic 
study documents.  After data analysis and dissemination is completed, hard copy forms will be 
boxed and sent to secure storage for 10 years at which time they will be shredded.  After data 
analysis and dissemination, electronic data and forms will be de-identified and transferred to a 
password-protected flash drive which will be sent to secure storage for 10 years at which time 
it will be destroyed.  
 
 
 
Cost/Budget 
 
Pharmacy Costs: 
• IV acetaminophen, $31.61/dose x 60 subjects  
 
       
 
       $1896.60 
• IV normal saline 100 mL bag, $1.40 /dose x 60 subjects   
 
 
            $84.00 
• Empty bottles, $5.13  x 120 subjects   
 
 
 
                    $615.60 
• Bottle hangers, $1.20 x 120 subjects  
 
 
 
                       $144.00 
• TriHealth Pharmacy fee, waived for staff study (per Steve Shepherd)   
 
 $0.00 
• Compounding Pharmacy  fee (Tristate Compounding Pharmacy & Kunkel   
Pharmacy) total from below  
 
 
 
 
 
          $420.00 
• 
Colored/Opaque Capsules (#120 = $20) 
• 
Acetaminophen 1000mg capsules (#60 = $210)  
• 
Placebo Capsules (#60 = $180.00) 

IV vs PO Acetaminophen Preoperatively     10 
 
 
 
 
 
Dissemination Costs: 
National experts have stated a study comparing IV and oral Acetaminophen is needed. 
Disseminating this information to a surgical audience will help patients even outside TriHealth 
and will allow TriHealth to be at the forefront of disseminating this new knowledge.  Ultimately 
the work will be published, but because of time required for publication, we are requesting 
presentation at a professional organization conference (likely the American Society of 
PeriAnesthesia Nurses, or ASPAN, 2019 conference) first to impact patients as quickly as 
possible.  Attendance at the (ASPAN 2019) conference is a requirement for poster submission 
and presentation. 
• Poster development =  
 
 
 
 
 
 
           $70.00 
• Conference fees for 2 presenters =  
 
 
 
                    $1000.00 
(cost estimated based on 2017 conference registration fees:   
$400 member/$600 non-member) 
• Travel costs for 2 presenters - mileage to Nashville from Bethesda  
Butler = 298 miles x $0.535 (current TriHealth mileage reimbursement)  
= 159.43 on way, roundtrip =               
 
 
 
 
           $318.86  
• Hotel for 2 presenters ($250/night x 3 nights) =  
 
 
 
           $750.00 
 
Total  
 
 
 
 
 
 
 
 
 
         $5299.06 
 
(Grant funding has been approved by the Bethesda Foundation) 
 
 
Estimated Period of Time to Complete Study 
When will study begin? 
January 1, 2018 (date awards dispersed) 
Protocol Development 
Completed 
2 weeks 
Admin Review Time 
2 weeks  
IRB Approval 
6 weeks 
Data collection 
3 months 
Data analysis 
2 weeks 
Presentation development 
(if applicable) 
2 weeks 
Manuscript Development 
(if applicable) 
1 month 
Journal submission process 
(if applicable) 
3 months 
Study closure 
1 month 
 
 
When and how will results be disseminated? 

IV vs PO Acetaminophen Preoperatively     11 
 
Results will be disseminated internally to the Bethesda Butler surgery leadership and system-
wide through the TriHealth Research Council.  Results will be disseminated nationally through 
presentation at a professional organization conference.  Finally, results will be disseminated 
nationally and internationally by publication in a relevant peer-reviewed journal. 
 
 
References 
 
Boggs, W. (2017).  IV acetaminophen curbs need for narcotics after C-section.  Medscape, 
http://bit.ly/2q1vKY3 
 
Hansen, R.N., Pham, A., Strassels, S.A., Balaban, S., & Wan, G.J. (2016).  Comparative analysis of 
length of stay and inpatient costs for orthopedic surgery patients treated with IV 
Acetaminophen and IV opioids vs IV opioids alone for post-operative pain.  Advances in 
Therapy, 33, 1635-1645. 
 
Jebaraj, B., Maitra, S., Baidya, D.K., & Khanna, P. (2013).  Intravenous paracetamol reduces 
postoperative opioid consumption after orthopedic surgery:  A systematic review of clinical 
trials.  Pain Research and Treatment.  http://dx.doi.org/10.1155/2013/402510 
 
Maund, E., McDaid, C., Rice, S., Wright, K., Jenkins, B., & Woolacott, N. (2011).  Paracetamol 
and selective and non-selective non-steroidal anti-inflammatory drugs for the reduction in 
morphine-related side effects after major surgery:  A systematic review.  British Journal of 
Anaesthesia, 106, 292-297. 
 
McNicol, E.D., Tzortzopoulou, A., Cepeda, M.S., Francia, M.B.D., Farhat, T., & Schumann, R. 
(2011).  Single-dose intravenous paracetamol or propacetamol for prevention or treatment of 
postoperative pain:  A systematic review and meta-analysis.  British Journal of Anaesthesia, 106, 
764-775. 
 
Moon, Y-E, Lee, Y-K, Lee, J., & Moon, D-E. (2011).  The effects of preoperative intravenous 
acetaminophen in patients undergoing abdominal hysterectomy.  Archives of Gynecology and 
Obstetrics, 284, 1455-1460. 
 
Remy, C., Marret, E., & Bonnet, F. (2005).  Effects of acetaminophen on morphine side-effects 
and consumption after major surgery:  Meta-analysis of randomized controlled trials.  British 
Journal of Anaesthesia, 94, 505-513. 
 
Salihoglu, Z., Yildirim, M., Demiroluk, S., Kaya, G., Karatas, A., Ertem, M., & Aytac, E. (2009). 
Evaluation of intravenous paracetamol administration on postoperative pain and recovery 
characteristics in patients undergoing laparoscopic cholecystectomy.  Surgical Laparoscopy 
Endoscopy & Percutaneous Techniques, 19, 321-323. 
 

IV vs PO Acetaminophen Preoperatively     12 
 
Song, K., Melroy, M.J., & Whipple, O.C. (2014).  Optimizing multimodal analgesia with 
intravenous acetaminophen and opioids in postoperative bariatric patients.  Pain Management 
Pharmacotherapy, 34, 14S-21S.