Indications
Perirenal blockade is used for a wide range of acute surgical and therapeutic conditions. The main goal of the manipulation is to relieve severe pain syndrome and spasm.
Key indications include:
- Relief of renal and biliary colic.
- Inflammatory diseases of the hepatobiliary zone: cholecystitis, biliary dyskinesia, pancreatitis.
- Acute abdominal processes: peritonitis, exacerbated gastric ulcer, dynamic intestinal obstruction.
- Vascular pathologies: early stage obliterating endarteritis.
- Antishock therapy in severe lower extremity trauma.
Topographic landmarks and patient positioning
The success of any topographical and anatomical manipulation begins with proper patient positioning. To perform a paranephric block, the patient must be placed on the healthy side. A mandatory condition is placing a firm bolster under the lumbar region. This position allows for maximum exposure of the target area.
Finding the injection point requires precise knowledge of projection anatomy. The physician identifies two key structures:
- Lower border of the 12th rib.
- Lateral edge of the erector spinae muscle (m. erector spinae).
The intersection of these two lines forms an angle. The apex of this angle serves as the site for inserting the long needle. The needle must be directed strictly perpendicularly to the patient's body surface.
Injection technique and success criteria
The needle insertion process requires extreme concentration from the surgeon. The needle is advanced deep into the tissues while continuously injecting 0.25% procaine solution. This technique allows for safe tissue dissection ahead of the needle tip.
The anatomical goal of the procedure is to pass through the retrorenal fascia and enter the free paranephric cellular space.
How can the surgeon verify that the needle has reached the correct layer? The primary and most reliable criterion for correct needle placement is cessation of backflow of fluid from the hub. As the needle passes through dense tissues, the injected solution tends to flow back. However, as soon as the needle bevel enters the perirenal adipose tissue, backflow stops completely.
Having confirmed the correct position, the physician administers the therapeutic dose of the anesthetic—from 60 to 80 ml. It is extremely important to remember that to achieve a full effect, the block is always performed bilaterally.
Complications and precautions
Despite its high clinical efficacy, paranephric block is considered a high-risk procedure. Due to the frequency of potential complications, the procedure has very strict indications.
During needle advancement, the following errors must be strictly avoided:
- Injury to the renal parenchyma. Insertion that is too deep or deviated from the perpendicular can lead to trauma to the organ tissue.
- Injection of procaine under the renal capsule. If the solution enters beneath the capsule rather than the free adipose tissue, it will cause acute distension.
- Injury to renal vessels. Wounding major blood vessels is fraught with hemorrhage.
- Penetration of the needle into the intestinal lumen. With gross violation of landmarks, there is a risk of puncturing the ascending or descending colon.
Briefly: answers to topical questions
Through which anatomical layers does the needle sequentially pass during a paranephric block?
During a paranephric block, the needle passes perpendicularly to the body surface through the lumbar fascia.
Sources describe the passage through the following layers:
- Lumbar fascia — its puncture is felt by the surgeon as overcoming resistance.
- Retrorenal fascia (fascia retrorenalis) — after penetrating it, the needle enters the target free paranephric cellular space.
Which nerve plexuses and ganglia are anesthetized during a paranephric block?
During a lumbar paranephric block, the injected anesthetic solution bathes and blocks several important autonomic nerve structures of the retroperitoneal space.
The following structures undergo anesthesia:
- Renal plexus (plexus renalis).
- Suprarenal plexus.
- Celiac plexus (plexus celiacus).
- Splanchnic nerves.
The mechanism of action is based on the distribution of procaine through the retroperitoneal adipose tissue where these plexuses lie.
Through which fascial spaces does the anesthetic spread after injection into the paranephric tissue?
After injection into the paranephric tissue, the anesthetic solution spreads throughout the retroperitoneal space.
The drug distributes directly through the retroperitoneal adipose tissue, bathing the nerve structures located there. At the same time, the perirenal cellular space (paranephron) is normally isolated from adjacent spaces due to the fusion of the anterior and posterior renal fasciae (fascia prerenalis and fascia retrorenalis).
To quickly find the injection point, remember the "Rule of the Twelve and the Erector": find the 12th rib and the erector spinae muscle. The apex of the angle between them is our target.
Class and exam questions
What position should the patient be in during the procedure?
The patient is placed on the healthy side, with a bolster securely placed underneath. This ensures optimal access to the injection zone.
How to determine that the needle has entered specifically the paranephric adipose tissue?
The main criterion is the complete cessation of fluid backflow from the needle. This occurs when the bevel penetrates through the retrorenal fascia into the free cellular space.
What volume and concentration of anesthetic are used?
60–80 ml of 0.25% procaine solution is injected into the perirenal adipose tissue. The procedure must be performed bilaterally.
Why is paranephric block performed only for strict indications?
Due to the high frequency of severe complications. Improper technique can lead to damage to the renal parenchyma or vessels, injection of the solution under the organ capsule, or puncture of the colon.
What else to study on this topic
- Topographic anatomy of the retroperitoneal space and renal fasciae.
- Mechanism of action of procaine in the relief of renal and biliary colic.
- Pathogenesis of shock in severe lower extremity trauma and the role of regional blocks.
- Differential diagnosis of conditions requiring paranephric block (peritonitis, pancreatitis, intestinal obstruction).
- Surgical tactics for accidental injury to renal vessels or the colon.
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