Spinal anesthesia depends on being able to locate physical landmarks on a patient's body. In obese patients, the commonly used landmarks may be difficult or even impossible to feel. In addition, the spine can be hidden beneath a layer of fatty tissue. Ultrasound is useful for finding the correct injection site in pregnant patients, but the usefulness of ultrasound has not been adequately evaluated in non-pregnant patients. The potential benefits for obese patients from the use of ultrasound include shortening the duration of the procedure, increasing patient comfort, decreasing the total number of attempts, and aiding in the choice of appropriate needle length for the patient. The investigators hypothesize that there is no difference in time to perform a spinal anesthetic when landmarking with ultrasound as compared to tactile landmarking in patients with BMI \> 35.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
67
The intervention group's interspaces will be determined using the curved linear probe on a Zonare ultrasound using two views.
Current clinical practice. Standard of care would have the attending anesthetist palpate the Tuffier's line to pinpoint the appropriate location for the spinal.
Subcutaneous local infiltration with a 25g needle we be performed prior to the spinal. Neuraxial technique will be attempted midline with a 25 gauge whitacre needle in the sitting position. Spinals will be attempted on either L2-L3, L3-L4, L4-L5 interspaces. The amount and type of local anesthetic/intrathecal narcotic will be left to the discretion of the Anesthetist.
Saskatoon City Hospital
Saskatoon, Saskatchewan, Canada
Saint Paul's Hospital
Saskatoon, Saskatchewan, Canada
Total time to perform the spinal
Time frame: From the beginning of palpation or ultrasound to free flow of Cerebral Spinal Fluid (CSF), up to 1 hour.
Time from administration of the local anesthetic needle until free flow CSF
Time frame: Up to 1 hour
Number of needle redirections
Time frame: At time of spinal anesthetic administration
Number of attempts to complete the spinal
As measured by new needle puncture sites, according to the anesthetist performing the procedure
Time frame: At time of spinal anesthetic administration
Number of failed blocks
Defined as unable to get free flow CSF or inadequate surgical block after administration of neuraxial anesthetic after 15 minutes.
Time frame: Up to 15 minutes after administration of spinal anesthesia
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