A spinal anesthetic may be placed on a patient in the lateral position for several reasons: The patient may require significant sedation; be at risk for a vasovagal reaction; have pain in the sitting position due to trauma or disease process, such as a fractured hip or perirectal abscess; or may be difficult to turn quickly after placement of the spinal due to morbid obesity. The lateral position is also very typically used if a hyperbaric or hypobaric one-sided spinal is planned. However, the advantages of having a patient in the lateral position are often offset by increased difficulty in correctly placing the spinal needle, especially if a midline approach is attempted. The issues to be aware of are the loss of visual anatomic landmarks, particularly the longitudinal midline bony landmarks, and the relative inability of patients to curl into the correct position to open the interspinous spaces.

Gravity can be blamed for increasing the chances of unintended deviation from the interspinous spaces in patients who are in the lateral position. Typically, less experienced anesthesia providers correctly palpate and appreciate the bony structures and spaces of the spinal column during the preparatory and draping phases but then use the visual cue of the longitudinal “dimple” in the soft tissue and skin in placing the introducer and spinal needles. Particularly in older or overweight patients, there can be as much as 1 to 2 cm of “sag” of the soft tissues towards the dependent side and it is extremely easy to get off the midline. A resident who is consistently contacting bone during a midline approach is usually tapping the dependent lamina. On repeated palpation of the bony structures and redirection of the needle, the true midline of these patients is almost always found to be “more towards the ceiling.”