Clinical trial NCT03315845: Neuraxial Anaesthesia: Does BMI Relate to Ease of Neuraxial Anaesthesia?
Official title: Neuraxial Anaesthesia: Does BMI Relate to Palpability of Bony Landmarks and Are Standard Needles a Suitable First Choice in Patients With BMI>30kg/m2
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Obesity
Neuraxial Ultrasound
Obstetric Anaesthesia
Keywords: BMI
obstetric anaesthesia
neuraxial anaesthesia
neuraxial ultrasound
difficult neuraxial anaesthesia
Lead sponsor: National Maternity Hospital, Ireland
Sponsor class: OTHER
First posted: 2017-10-20
Enrollment: 100
Sex: FEMALE
Minimum age (years): 16
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Obstetric patients with BMI \>30kg/m2, presenting in a non-emergency situation.

Brief summary: Neuraxial anaesthesia can be more difficult and associated with more complications if the patient's bony landmarks are difficult to palpate. They are more likely to be difficult to palpate if a patient has a high Body Mass Index (BMI), (\>30kg/m2). The depth that the spinal or epidural needle must be inserted is usually longer in these patients with high BMIs. We wish to palpate the backs of at least 100 such patients to see how many of them have impalpable bony landmarks. We then wish to use ultrasound to measure the distance from skin to the posterior epidural complex to discover if this length is longer than the standard needle length. If it is longer in the majority of people we study, we will recommend changing standard practice to start using a longer needle for all first attempts at neuraxial anaesthesia in this patient population.

Detailed description: Complications rates including failure are higher in obese patients undergoing anaesthesia procedures. Anaesthetists have adopted the use of ultrasound to assist in overcoming these difficulties. Neuraxial ultrasound is proving to be beneficial in those patients in whom identification of interspinous spaces is difficult and most of these patients are obese.

In our institution, there is a 'standard practice' for neuraxial procedures, with a 'standard' needle used for first attempts (Whitacre 25G 90mm for spinal, Tuohy 18G 80mm for epidural). If the operator has not reached the desired space (spinal or epidural) with the needle inserted to 8cm, a longer needle is then considered for further attempts. This exposes the patient to at least one extra neuraxial needle insertion. Studies have shown that increased needle insertions and redirections are associated with increased complications.

We hypothesised that a large number of patients with BMI\>30kg/m2 would have a depth of spinal/epidural space that is greater than the length of the 'standard' needle used. Therefore we suggest that practice should change to use the longer needle or a combined spinal-epidural on the first attempt in these patients.

To test our hypothesis, we will assess the ease of palpation of the following anatomical landmarks: anterior and posterior iliac crests; lumbar spinous processes; scapulae; and sacral cornua. We will then perform neuraxial sonography of the lumbar spine, measuring depth to epidural space. Finally we will measure waist circumference in those patients with BMI \<30kg/m2.

Eligibility criteria: Inclusion Criteria:

* Recorded BMI \>30kg/m2; ability to give consent; non-emergency cases.

Exclusion Criteria:

* Previous metal work to lumbar spine.

Primary outcomes:
measure: Palpability of bony landmarks for neuraxial anaesthesia
timeFrame: 4 months
Secondary outcomes:
measure: Ultrasonographic distance from skin to posterior epidural complex
timeFrame: 4 months
Other outcomes:
Locations:
Study officials:
affiliation: National Maternity Hospital, Ireland
name: Kevin McKeating
role: STUDY_DIRECTOR
References:
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