SUPINE POSITION: USES AND PRECAUTIONS - ANATOMY AND PHYSIOLOGY - 2025

The supine or dorsal decubitus is an anatomical position in which the individual lies face up. The word "decubitus" has its origin in the Latin decumbere, which means "lie down" or "lie down." "Supino" also has Latin origin in the word supinus, which is understood as being supported on the back or with the palm of the hand facing upwards.

The term supine also refers to a foolish, unreasonable or lazy person. Perhaps laziness refers to the supine position, since lying on the back is the typical body expression of someone who does not feel like getting up or doing any activity.

characteristics

This anatomical position, in addition to including lying on your back, has other peculiarities, including:

- Body in a horizontal position parallel to the ground.

- Neutral neck position.

- Look at the sky or ceiling. Technically it is described as gaze at the zenith.

- Arms close to the body.

- Legs extended with feet in neutral position. Fingertips point upward at an angle of approximately 75º.

There is some controversy regarding the situation of the hands. The concept of supination of the hands implies that the palms face upwards while in an anatomical position, but more often than not, while the body is in the supine position, the hands are prone with the thumbs facing the central axis of the body..

The parts of the body that support the supine position are the occiput, the back, the elbows, the buttocks, the back of the thighs and the heels. This position is useful to virtually divide the body into imperfect halves according to the three axes of the plane:

Anteroposterior axis

It divides the body into two parts, namely: ventral, the part of the body that is not supported and looks up; and dorsal, the part of the body resting on the surface.

Craniocaudal axis

It separates the body into two inaccurate halves from each other. The upper half, cranial or cephalic, is everything that is above the axis that cuts the body above an imaginary line that passes just above the iliac crests.

On the other hand, the lower or caudal half is basically represented by the lower limbs and the pelvis.

Transverse axis

It divides the body into two theoretically equal halves, right and left, as long as the axis precisely crosses the midline of the body.

Applications

Many clinical activities make use of the supine position to achieve their goals. Among the most important activities we have the following:

Surgery

The supine position is the most used in surgical procedures. Many specialties approach the patient while in such a position, such as general surgery, chest surgery, head and neck surgery, trauma, gynecology and obstetrics, cardiovascular surgery, and urology. Anesthesiologists intubate the patient primarily in that position.

Radiology

Many imaging studies are done with the patient lying on their back. Not only basic radiographs or x-rays, but also most axial CT scans and MRIs are done with the patient in the supine position. The same goes for abdominal and pelvic ultrasounds.

Physiotherapy

An important number of physiotherapeutic techniques are carried out in the supine position. In fact, bedridden patients receiving physical therapy are compulsorily lying on their backs. Communication with the patient is much better if he lies in this position while exercises or maneuvers are being performed.

odontology

Several dental procedures are carried out with the patient in the supine position or one of its variations. Even maxillofacial surgeons prefer this position for most of their intraoral operations.

Sudden infant death syndrome

The death rate associated with sudden death syndrome in young children or infants has greatly decreased in recent years.

This decrease appears to be due to the fact that the most recent studies recommend avoiding the prone position to reduce the risk of rebreathing carbon dioxide.

Others

The physical examination par excellence in any specialty is performed with the patient in this position. In the application of cardiopulmonary resuscitation maneuvers or CPR, the person is in the supine position. Even in pathological anatomy, autopsies are done with the patient lying on her back.

As can be seen, it is the most widely used patient position in the medical world, followed by far by the prone and lateral decubitus.

There are many accepted variations of the supine position for clinical use, such as the gynecological position, lithotomy position, Trendelenburg and its inverted, Fowler and semi-sitting variant.

Precautions

While this position is very useful and versatile, not a few pathological conditions have been linked to it. Some of the most important are described below:

Sleep apnea

Obstructive sleep apnea has been shown to be more common and severe when people sleep on their backs.

This is due to an increased risk of airway collapse due to its more anterior location, lower lung volume, and the inability of the respiratory muscles to maintain the luxury of permeable air.

Fetal bradycardia

During uterine contractions episodes of fetal bradycardia occur if the mother is in the supine position.

This was demonstrated by several studies evaluating fetal health in labor with mothers in supine or lateral decubitus position. The percentage of bradycardia decreased when the mother lay on her side.

Bronchial aspiration

Patients in the immediate postoperative period or with intestinal obstruction are at increased risk of aspiration if they are in the supine position.

If intra-abdominal pressure overcomes the support of the esophageal sphincter, which is more likely if the person is lying on his back, gastric contents can return to the esophagus and even pass into the airways.

Orthopnea

Patients with advanced congestive heart failure cannot tolerate supine decubitus. Orthopnea - breathing difficulties when the person is lying down - is a common symptom of heart failure related to the mismanagement of the volumes of blood that reach and leave the heart.

References

1. Registered Nurse (2018). Supine Position: Definition, Explanation, Pros, and Cons. Recovered from: topregisterednurse.com
2. Walls, Jason (2017). Patient Positioning During Anesthesia: Supine Position. Recovered from: clinicalpainadvisor.com
3. Wikipedia (latest edition 2017). Supine position. Recovered from: en.wikipedia.org
4. Warland, Jane (2017). Back to basics: avoiding the supine position in pregnancy. The Journal of Physiology, 595 (4): 1017-1018.
5. Abitbol, ​​MM (1985). Supine position in labor and associated fetal heart rate changes. Obstetrics and Gynecology, 65 (4): 481-486.
6. Ng, MT; Sun, WH; Cheng, CW and Chan, ES (2004). Supine position is safe and effective for percutaneous nephrolithotomy. Journal of Endourology, 18 (5): 469-474.
7. Berger, M et al. (1997). Avoiding the supine position during sleep lowers 24 h blood pressure in obstructive sleep apnea (OSA) patients. Journal of Human Hypertension, 11 (10): 657-664.
8. Joosten, SA et al. (2014). Supine position related obstructive sleep apnea in adults: pathogenesis and treatment. Sleep Medicine Reviews, 18 (1): 7-17.
9. Walter, LM et al. (2017). Back to sleep or not: the effect of the supine position on pediatric OSA: Sleeping position in children with OSA. Sleep Medicine, 37: 151-159.