Optimizing the Paracetamol Dose for Prevention of Post-Spinal Shivering in Lower Limb Orthopedic Surgeries

NCT07855575 | Not Yet Recruiting Phase 4

• 1 other identifier: Paracetamol Dose for Shivering
• Study Type: interventional
• Target: 150
• Locations: 0 countries
• Sites: N/A

Brief Summary

Shivering is a common and distressing complication following spinal anesthesia, affecting up to 70% of patients. It significantly increases oxygen consumption, places stress on the cardiovascular system, and interferes with postoperative monitoring. While intravenous paracetamol has been shown to reduce post-spinal shivering without the sedation or respiratory side effects associated with other medications, existing trials have only investigated a standard 1-gram dose. This study aims to evaluate whether a higher dose of intravenous paracetamol (2 grams) provides superior prevention of post-spinal shivering compared to the standard 1-gram dose and an inactive placebo. Adult patients scheduled for elective lower-limb orthopedic surgery under spinal anesthesia will be randomly allocated to one of three study groups:

• High-dose group: intravenous paracetamol 2 g
• Standard-dose group: intravenous paracetamol 1 g
• Control group: intravenous normal saline placebo Each infusion will be administered over 15 minutes immediately prior to spinal anesthesia. Participants will be observed intraoperatively and for at least 60 minutes in the post-anesthesia care unit (PACU) to measure the incidence and severity of shivering, core body temperature changes, the need for rescue medication, and any adverse events.

Conditions

Shivering; Postoperative Shivering; Hypothermia

Keywords

Paracetamol; Acetaminophen; Spinal Anesthesia; Lower Extremity Surgery; Orthopedic Procedures; Dose-Response Relationship; Post-Spinal Shivering; Thermoregulation

Outcome Measures

Primary Outcomes (1)

• Percentage of Participants With Clinically Significant Post-Spinal Shivering

  Clinically significant shivering is defined as a shivering score \>= 3 on the Crossley and Mahajan Shivering Grading Scale. The scale ranges from Grade 0 to Grade 4: Grade 0 = No shivering; Grade 1 = Piloerection or peripheral vasoconstriction without visible muscular activity; Grade 2 = Muscular activity confined to one muscle group; Grade 3 = Muscular activity involving more than one muscle group, but not generalized; Grade 4 = Gross muscular activity involving the whole body. Higher grades indicate greater shivering severity.

  Up to 4 hours post-spinal injection

Study Arms (3)

Group H: High-Dose Paracetamol (2 g)

EXPERIMENTAL

Patients receive intravenous paracetamol 2 g diluted in 500 mL volume, infused over 15 minutes, commencing immediately prior to intrathecal injection.

Drug: Paracetamol 2 g

Group S: Standard-Dose Paracetamol (1 g)

ACTIVE COMPARATOR

Patients receive intravenous paracetamol 1 g diluted in 500 mL volume, infused over 15 minutes, commencing immediately prior to intrathecal injection.

Drug: Paracetamol 1 g

Group C: Placebo Control

PLACEBO COMPARATOR

Patients receive 500 mL of intravenous normal saline (0.9% sodium chloride), infused over 15 minutes, commencing immediately prior to intrathecal injection.

Drug: Normal Saline Placebo

Interventions

Paracetamol 2 g DRUG

Intravenous paracetamol 2 g in 500 mL volume, administered as an intravenous infusion over 15 minutes immediately prior to intrathecal injection.

Group H: High-Dose Paracetamol (2 g)

Paracetamol 1 g DRUG

Intravenous paracetamol 1 g in 500 mL volume, administered as an intravenous infusion over 15 minutes immediately prior to intrathecal injection.

Group S: Standard-Dose Paracetamol (1 g)

Normal Saline Placebo DRUG

Intravenous 0.9% normal saline 500 mL, infused over 15 minutes immediately prior to intrathecal injection, matched in volume and appearance to preserve blinding.

Group C: Placebo Control

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18 to 65 years
• American Society of Anesthesiologists (ASA) physical status I or II
• Scheduled for elective lower-limb orthopedic surgery under spinal anesthesia
• Expected surgical duration between 1 and 3 hours
• Willingness to provide written informed consent

You may not qualify if:

• Patient refusal or inability to provide informed consent
• ASA physical status \>= III
• Contraindications to spinal anesthesia (e.g., coagulopathy, local infection at injection site, severe spinal deformity)
• Known allergy or hypersensitivity to paracetamol or the local anesthetic used
• Baseline (preoperative) core/tympanic temperature \< 36.5°C or \> 37.5°C
• Pre-existing hepatic, renal, or thyroid disorders
• History of seizure disorder
• Chronic alcohol use, malnutrition, or any condition predisposing to hepatotoxicity
• Body mass index (BMI) \> 35 kg/m²
• Pregnancy or lactation
• Chronic use of antipyretic or anti-inflammatory medication within 24 hours of surgery
• Cardiac arrhythmia or hemodynamic instability

Sponsors & Collaborators

• Assiut University: lead

MeSH Terms

Conditions

Hypothermia

Interventions

Acetaminophen

Condition Hierarchy (Ancestors)

Body Temperature Changes; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Acetanilides; Anilides; Amides; Organic Chemicals; Aniline Compounds; Amines

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Resident

Study Record Dates

• First Submitted: September 28, 2026
• First Posted: October 2, 2026
• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: October 2, 2026

Record last verified: 2026-09