sacroiliac infiltration

Spinal anesthesia: When is it indicated? (procedure, risk)

Article reviewed and approved by Dr. Ibtissama Boukas, physician specializing in family medicine

La spinal anesthesia is one of types of anesthesia commonly applied in lower body surgeries. Because of its simplicity, it is advantageous compared to other anesthesias. It is infratoxic due to a minimal injection dose. However, it has limitations, especially in terms of complications. Discover in this article more information on the spinal anesthesia : definition, indications and contraindications, procedures to follow, risks and complications.

Definition of spinal anesthesia

La spinal anesthesia ou spinal anesthesia is a technique local and regional anesthesia generally intended for lower part of the body.


It consists of puncture at the level of the lower back between two vertebrae lumbar and to achieve injection of anesthetic substance in the fluid surrounding the spinal cord : the liquid cerebrospinal (or CSF).

To reach the CSF, spinal anesthesia requires to cross the dura mater (one of the meninges or membranes of the central nervous system) by injection intrathecal. That is, through a partition of an intervertebral space of the lumbar spine, in contact with the last medullary nerve roots.

La spinal anesthesia is a great option because of its benefits. In fact, it acts faster. It is a more complete anesthesia although the dose of the anesthetic substance used is lower.

Moreover, it takes precedence over the maintenance of vigilance as well as the safety it offers (during and after the operation) if the procedures are followed correctly. Spinal anesthesia can also be performed in precarious conditions.

Indications for this locoregional anesthesia

La spinal anesthesia is mainly indicated for patients who have to undergo surgery on the lower part of the body.

Lower limb operations

In case of orthopedic and vascular surgeries.

Subumbilical abdominal surgery

In this case spinal anesthesia must sometimes be combined with general anesthesia. The most common indications are:

  • la wall surgery (treatment of hernia and eventration) and colon surgery (colostomy);
  • la obstetric surgery (caesarean section, ectopic pregnancy) and surgery on the genitals (hysterectomy, salpingectomy, ovarian cysts);
  • la urologic surgery (high and low prostatectomy, operation of the bladder or ureter);
  • the visceral surgeries (colon operation…) and proctologic surgeries (anal fissures and treatment of hemorrhoids).

On whom can spinal anesthesia be performed?

The people targeted for spinal anesthesia are patients who present risk factors, particularly with general anesthesia. These include people who have certain pathologies such as:

  • cardiac history;
  • respiratory diseases;
  • renal pathologies (kidney failure, etc.);
  • liver disease;
  • metabolic problems (as in the case of diabetes…)

Contraindications of spinal anesthesia

Although the spinal anesthesia has many advantages, it also has contraindications. These can be absolute or relative.

Absolute contraindications

La spinal anesthesia is totally proscribed in the following cases:

  • uncorrected hypovolaemia;
  • blood clotting disorders;
  • sepsis or severe inflammation at the puncture site;
  • patient refusal.

Relative contraindications

According to individuals, the spinal anesthesia is contraindicated in cases of:

  • neurological deficit, migraine and spinal diseases ;
  • spinal malformations, a history of sciatic or low back pain;
  • febrile syndromes;
  • too young subjects (due to the high risk of headaches after the puncture).

How is spinal anesthesia performed?

The procedures include the preparation and achievement de spinal anesthesia proper. They must be done in a calm atmosphere to avoid distressing the patient.

The preparation

Mine consulting

A consultation is essential as soon as spinal anesthesia is considered. It allows to ask indications according to the state of the patient, his medical history, his age, etc.

It is during this consultation that the doctor carries out various exams (that of the patient's skin condition, for example).

It also aims to obtain the consent of the patient, who must be informed beforehand about the risks and complications as well as the advantages of the spinal anesthesia.


La premedication consists of the administration of atropine and diazepam directly intravenously. This step is helpful in preventing possible discomfort or problems associated with the parasympathetic nervous system.

Preparation of materials

It consists in the sterilization of the materials necessary for the spinal anesthesia. We mainly find:

  • a 25 gauge fine needle (0,5mm diameter) or 22G (0,8mm) pencil point bevel;
  • un introducer, two 5 ml syringes et two subcutaneous needles (to take the drugs and do the local skin anesthesia).
  • A drape, compresses, a cup (for the antiseptic), a pair of gloves and an occlusive dressing are also essential.

Preparation of anesthetic and resuscitation drugs

The anesthetist prepares the anesthetic and resuscitation drugs. They are chosen and prepared at a dose and concentration varying according to the patient's condition and his medical background.

The main anesthetic substances used for spinal anesthesia are there lidocaine and bupivacaine.

For emergency resuscitation, drugs such as morphine substances (fentanyl, sufentanyl, etc.) are administered.

Adjuvants are also sometimes injected: adrenaline, ephedrine, etc.

Patient preparation

La preparing the patient for surgery is based on the examination of its parameters: pulse, blood pressure, body temperature.

A good caliber venous line is set up, then 500 to 1000 ml of crystalloids (physiological serum or ringer's lactate) are injected.

Performing anesthesia

Once ready, you can move on to spinal anesthesia. First, we install the patient so that he has the round back (sitting with the forearms bent, resting on the thighs for example).

Then we chooses the puncture point easy to stitch and we make a landmark by tracing the outlines of spinous processes and a horizontal line.

All these procedures are carried out in compliance with the rules of asepsis. The surgeon must be equipped with a cap, a mask and sterile gloves. Surgical hand washing is also essential.

The entire back of the operated patient will also be disinfected. This consists of cleaning with soap and water, followed by the application, in a spiral motion (from the puncture point outwards), of antiseptic or disinfectant (such as alcohol).

Then one local anesthesia per 1 ml of lidocaine for example is injected, to alleviate the pain during the lumbar puncture.

The realization of this puncture is done in two stages.

  • The needle is introduced through the introducer and progress is made until resistance is encountered which would correspond to the dura mater (3 to 6 cm deep), while avoiding bone contact.
  • The mandrel is removed, and the clear CSF drop reflux is observed before slowly inject local anesthesia (1 ml every 3 seconds). Care must be taken that the needle is stationary and has a good position.

Finally, the patient is placed in the supine position.

Monitoring after anesthesia

Monitoring takes place during the installation of the block, during and after the operation.

It consists of evaluating:

  • the feelings of the patient;
  • sensory block;
  • the engine block;
  • breathing;
  • consciousness ;
  • pulses;
  • blood pressure.

Monitoring should be frequent, until the patient has fully recovered. They are essential in order to limit the risks and complications.

The risks and complications

During the puncture, there is a high risk of vagal discomfort. However, it is quite possible to avoid it by adopting the lateral decubitus position and premedication.

The failures as well as accidents may also occur (example: puncture of a vessel).

When installing the block, in the event of a block that is too extensive, risks and complications neurological, cardio-respiratory and digestive can present themselves. These can cause side effects such as low blood pressure, bradycardia, drowsiness, difficulty breathing and drowsiness.

Later, one may experience headaches, urinary retention, paralysis, sepsis and other neurological complications.

However, these risks and complications can be treated and avoided by strictly adhering to spinal anesthesia procedures and protocols.


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