A Comparative Study of Supine Position and the Head Elevated Position on the Level of Sensory Block After Spinal Anesthesia in Morbidly Obese Parturient Undergoing Elective Cesarean Delivery

A Comparative Study of Supine Position and the Head Elevated Position on the Level of Sensory Block After Spinal Anesthesia in Morbidly Obese Parturient Undergoing Elective Cesarean Delivery

The sniffing position defined as neck flexion with upper cervical extension, is traditionally recommended for general anesthesia induction, as it improves laryngoscopic views. However, the head elevation beyond the sniffing position, also known as ramped position or head elevated laryngoscopy position, usually achieved by specially designed pillows such as the Oxford head elevating laryngoscopy pillow (Alma Medical,Oxford, UK) or the Troop® elevation pillow (Mercury Medical, Clearwater, FL, USA)has been shown to not only increase respiratory reserve but also to improve laryngeal views in patients undergoing bariatric surgery. Additionally it helps in pre-oxygenating the patient more efficiently by keeping the airway patent and provides easier bag-mask ventilation.

It may also benefit the term parturient in a similar way by improving functional residual capacity (FRC), ventilation and comfort. However, this positon may affect the cephalad spread of the intrathecal local anesthetic.

Two earlier studies looked at the intrathecal local anesthetic spread in obstetric patients when placed in the head elevated laryngoscopy position, and both suggested poor cephalad spread, with patients requiring higher supplementation.

However, both studies excluded morbidly obese patients. The Investigators hypothesized that in obese parturients with BMI more than or equal 40, higher intra-abdominal pressures and possibly lower CSF volumes will counteract the poor cephalad spread associated with this position. The aim of this study is to determine the effect of a ramped position on intrathecal local anesthetic spread in the morbidly obese term parturients with BMI more than or equal 40 undergoing elective Cesarean delivery(CD).

Inclusion Criteria:

• Age 18yrs of age or more
• BMI 40 or more and more than or equal 37 weeks of gestation
• elective CD
• consented for neuraxial anesthesia
• singleton fetus
• ASA class 3 (no co-morbidities except morbid obesity, gestational diabetes, and gestational hypothyroidism)

Exclusion Criteria:

• Age <18 years
• BMI less than 39.9 and <37 weeks of gestation
• parturient preference for general anesthesia or contraindication to neuraxial anesthesia
• Women with comorbidities other than obesity, gestational diabetes or gestational hypothyroidism.
• women in active labor (>3 cm dilated with regular uterine contractions)
• emergency CD
• Possible uterine over-distension or under-distension (e.g. polyhydramnios, estimated fetal weight >4 kg by ultrasound scan, or oligohydramnios or concern for fetal IUGR)
• maternal height <150 cm or >180 cm.
• Patients for which more than 2 minutes is taken in positioning after anesthesia induction (Time 0).