Supine Position · What Is It, Uses, and More

The supine position is commonly used during induction of anesthesia and emergence from anesthesia during a surgical procedure. It is also used in several types of surgery, including cranial surgery, where the flexibility of the neck and the ability to rotate the torso allows access to most brain lesions. Similarly, neck and face procedures and plastic surgeries are done with the individual in the supine position. 

Other surgeries where the supine position is utilized include cardiac, colorectal, thoracic, and abdominal surgeries. Additionally, surgeries involving the upper extremities (e.g., hands and wrists) and lower extremities (e.g., the hips, knees, feet, and ankles) can be performed with the individual in the supine position. Lastly, endovascular and laparoscopic surgeries, which are minimally invasive, are commonly performed while the individual is supine. 

The supine position allows the surgeon to access the anterior structures of the body and provides stability to the body on the operating table. The supine position is highly versatile and is used for several procedures, allowing anatomical structures of the face, neck, abdomen, and extremities to be natural and neutral. Safety straps can be applied, and the entire body can be supported, thereby limiting the risk of falling from the table or injuring oneself.

In addition to surgical procedures, several physical examination procedures can be performed in the supine position. For example, a clinician can do a musculoskeletal examination of the hip and groin with the individual in a supine position. The clinician can inspect the skin for swelling, scars, lesions, ecchymosis, and erythema. They may  compare the hips and lower extremities to assess for asymmetries and discrepancies in leg length. They may also palpate the quadrants of the abdomen and the pubic symphysis for tenderness. Several bones and soft tissue structures, such as the adductor tendon, lateral rectus abdominis muscle border, and the iliac crest, can be evaluated and palpated with the person lying supine. 

While the supine position is widely used in surgery and during physical examination, risks of the prolonged supine position include effects on respiratory function, skin integrity, and circulation.

Respiratory Function

When placed in the supine position, intra-abdominal organs shift and compress lung tissue, leading to decreased functional residual capacity (FRC) (i.e., the air remaining in the lungs after a normal, passive exhalation). When standing, the typical FRC of an individual range from 2.5 to 3.5 liters. The supine position reduces the FRC by 0.8 to 1 liters while the individual is awake and further decreases by 0.4 to 0.5 liters under anesthesia. When standing, the typical FRC of an individual range from 2.5 to 3.5 liters. Most healthy individuals can maintain adequate respiratory function even during anesthesia; however, this significant decrease in FRC might be problematic for those with obesity, pulmonary disease, and those at increased age. Additionally, those in the advanced stages of pregnancy can be at risk of compressing their abdominal aorta and inferior vena cava when in the supine position. 

Skin integrity

Another potential risk of being in the supine position for a prolonged period is the development of pressure sores and ulcers. This is particularly common on the bony prominences, such as the back of the skull, scapulae, elbows, sacrum, coccyx, and heels.  Surgical positioning pads are often used during lengthy procedures. Additionally, the arm boards are positioned level with the table and abducted less than 90 degrees from the body to protect from nerve compression and stretching of the brachial plexus and ulnar nerves. 

Circulation

Lastly, when in supine position, heart rate and peripheral vascular resistance (i.e., the resistance in the circulatory system that is used to create blood pressure) are lower when compared to sitting. Elevating the legs can increase the amount of blood that returns to the heart, thereby increasing the amount of blood supplied to the body by the heart.