Hypobaric L5-S1 Study

NCT06526156 | Active Not Recruiting

• 2 other identifiers: 24-5192CAPCR# 24-5192
• Study Type: observational
• Target: 55
• Locations: 1 country
• Sites: 1

Brief Summary

Patients going through total hip or knee replacement (arthroplasty) have to be put under spinal anesthesia to prevent them from feeling any pain during surgery. Spinal anesthesia means having a small needle inserted between the bones of the lower lumbar spine (vertebrae). The choice of space used is decided by the anesthesiologist in charge of patient care. The space between these bones is often narrowed by arthritis or other age-related degenerative spine disease in patients having total hip or knee replacement surgery. The lowest L5-S1 (Lumbar 5- Sacral 1) space is the largest one and often least affected by arthritis, which makes it the easiest option. Despite this, it is not currently the most common space used for spinal anesthesia, because it is hard to find by palpation (feeling the bones through the skin), and because there is concern that local anesthetic will not always spread up high enough from this lowest space, which is needed for a successful spinal anesthesia. How far it spreads depends on the amount (dose) and density of local anesthetic given. There are two types of local anesthetic: one called isobaric, which has the same density as CSF (Cerebro-Spinal Fluid), and another called hypobaric, which has lower density than CSF. Isobaric local anesthetic spreads evenly throughout the CSF irrespective of patient positioning. However, a larger dose is required to achieve adequate anesthesia for surgery. Using larger doses, leads to a very long duration of sensory and motor block, far in excess of that required for surgical completion which leads to a slower recovery from anesthesia. Hypobaric local anesthetic, on the other hand, floats in CSF like oil on water. This allows anesthesiologists to use a smaller dose while still being sure that it will spread high enough to achieve adequate anesthesia for surgery. The smaller doses in turn allow for faster recovery of normal movement and feeling in the legs of patients after surgery. It has been observed that all of these dilemma can be solved by:

1. 1.Using ultrasound imaging to find and mark the space, and
2. 2.Injecting hypobaric local anesthetic.

Conditions

Anesthesia; Anesthesia, Local

Keywords

Total Hip Arthroplasty; Total Knee Arthroplasty; Bupivacaine

Outcome Measures

Primary Outcomes (10)

• Rate of successful spinal anesthesia

  "Successful spinal anesthesia" is defined as the completion of surgery without conversion to general anesthesia, administration of supplemental opioids or surgical local anesthetic infiltration in the operating room to manage surgical pain.

  Assessed from time of spinal injection to surgery completion

• Most cranial dermatomal level of sensory anesthesia achieved before surgery

  A pinprick test using an 18G(gauge) blunt-tipped needle (BD Blunt Fill needle) will be performed on non-dependent and dependent sides to detect sensory loss over the torso and lower limbs. Sensation to pinprick testing in each dermatome will be categorized as normal ("sharp" sensation), analgesia ("dull" sensation), or anesthesia ("no" sensation). The most cephalad/cranial (upper) sensory block level of analgesia and anesthesia will be recorded based on the dermatomal map.

  Assessed every 5 minutes for the first 30 minutes after spinal injection

• Time to reach the most cranial dermatomal level of sensory anesthesia before surgery

  The most cranial dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed from time of spinal injection to surgery commencement

• Time to reach sensory anesthesia at level of T10 or higher before surgery, on the operative limb

  The dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed from time of spinal injection to surgery commencement

• Time to reach sensory anesthesia at level of L1 or higher before surgery, on the operative limb

  The dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed from time of spinal injection to surgery commencement

• Time to recovery of normal sensation at T10 or lower (also defined as duration of sensory analgesia at T10 or higher) in both lower limbs

  The dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed at the end of surgery and every 30 minutes in the post-anesthesia care unit (PACU) or inpatient ward until a return of normal sensation in the T10 dermatome has been documented

• Time to normal sensation at L1 or lower (also defined as duration of sensory analgesia at L1 or higher) in both lower limbs

  The dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed at the end of surgery and every 30 minutes in the PACU or inpatient ward until a return of normal sensation in the L2 dermatome has been documented on the day of surgery.

• Time to recovery of normal sensation at L2 or lower in both lower limbs

  The dermatomal level of sensory anesthesia will be determined based on the pinprick test.

  Assessed at the end of surgery and every 30 minutes in the PACU or inpatient ward until a return of normal sensation in the L2 dermatome has been documented on the day of surgery.

• Time to achieve complete motor block at hip, knee, ankle, and toes

  The development of motor block will be assessed by assessing the ability to actively flex and extend at the hip, ankle, knee, and toes. This will be scored as either 1 (movement present and observed) or 0 (movement absent) at each joint on both lower extremities.

  Assessed every 5 minutes for the first 30 minutes after spinal injection

• Time to regain ability to move hip, knee, ankle, and toes; and a score of 0 on the modified Bromage scale

  Modified Bromage scale scores: 0 - Able to move hip, knee, ankle and toes 1. \- Unable to move hip, able to move knee, ankle and toes 2. \- Unable to move hip and knee, able to move ankle and toes 3. \- Unable to move hip, knee and ankle, able to move toes 4. \- Unable to move hip, knee, ankle, or toes

  Assessed at the end of surgery and every 30 minutes in the PACU or inpatient ward until full motor recovery has been achieved in both lower limbs on the day of surgery.

Secondary Outcomes (7)

• Time to scan, locate and mark the L5-S1 space

  Assessed before surgery

• Time to perform the spinal anesthetic

  Assessed before surgery

• Number of needle passes

  Assessed before surgery

• Incidence of adverse effects after spinal anesthesia

  Assessed after the end of surgery and during the patient's stay in PACU or in-patient ward on the day of surgery.

• Patient satisfaction with anesthesia care, based on Likert scale

  Assessed at the last study assessment visit, when regression to L2 has been documented either in PACU or in-patient ward on the day of surgery.

Study Arms (1)

Hypobaric L5-S1 Spinal Anesthesia

Will receive a dose of hypobaric (0.33%) bupivacaine, administered at the L5-S1 space.

Drug: Bupivacaine injection

Interventions

Bupivacaine injection DRUG

A 3 mL hypobaric (0.33%) solution of bupivacaine, prepared by mixing 2 mL of isobaric (0.5%) bupivacaine with 1 mL of sterile water. Dural puncture will be performed using a 25 or 27G (gauge) spinal needle at the L5-S1 intervertebral space, and the 3 mL of 0.33% bupivacaine will be injected into the intrathecal space.

Also known as: Marcaine

Hypobaric L5-S1 Spinal Anesthesia

Eligibility Criteria

• Age: 20 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adults aged at least 20 years having inpatient elective unilateral total hip or knee arthroplasty surgery

You may qualify if:

• Patients undergoing elective unilateral total hip or knee arthroplasty under spinal anesthesia at TWH who are scheduled for inpatient overnight admission
• American Society of Anesthesiologists physical status class (ASA-PS) 1-3
• At least 20 years of age

You may not qualify if:

• Refusal to participate
• Inability to communicate due to language barrier or cognitive impairment
• Height \> 200 cm
• Weight \>120 kg
• Body mass index (BMI) \>45 kg/m\^2
• Contraindication or allergy to amide-type local anesthetic
• Contraindication to spinal anesthesia at the L5-S1 space (e.g., infection at the injection site, existing coagulopathy, severe spinal stenosis at higher vertebral levels)
• Previous spinal surgery in the lumbosacral spine
• Spinal anesthesia performed in the operating room rather than the block room
• Spinal anesthesia that includes administration of intrathecal opioids (e.g., morphine, fentanyl)
• Pre-existing sensory or motor impairment in the lower extremities
• Inability to identify the L5-S1 space with ultrasonography

Sponsors & Collaborators

• University Health Network, Toronto: lead

Study Sites (1)

Toronto Western Hospital

Toronto, Ontario, M5T 2S8, Canada

Location

MeSH Terms

Interventions

Bupivacaine

Intervention Hierarchy (Ancestors)

Anilides; Amides; Organic Chemicals; Aniline Compounds; Amines

Study Officials

• Ki Jinn Chin, MBBS,MMed,FRCPC

  UHN

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 11, 2024
• First Posted: July 29, 2024
• Study Start: July 22, 2024
• Primary Completion: March 20, 2025
• Study Completion: December 31, 2025
• Last Updated: November 20, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will not share

Locations

CA (1)