Spinal Anesthesia
Spinal anesthesia is considered the technique of choice for Transurethral resection of the prostate (TURP), primarily due to its advantages in this particular population. It is especially useful for elderly patients who often have compromised respiratory function. Spinal anesthesia provides adequate analgesia, helps reduce the stress response to surgery, and enables continuous monitoring of the patient's neurological status, which is a crucial advantage in detecting early signs of TURP syndrome or bladder perforation. Under spinal anesthesia, patients remain conscious, allowing them to report symptoms such as periumbilical or shoulder pain, which are indicative of bladder perforation or capsular tears.
Spinal anesthesia does not abolish the obturator reflex. Current from the resecting loop passing through the lateral bladder wall or a lateral prostatic lobe can stimulate the obturator nerve directly, producing a sudden adductor jerk of the thigh that can drive the loop through the bladder wall. Because the stimulus acts on the nerve distal to the spinal block, the reflex persists under a spinal; options are an obturator nerve block, a switch to bipolar energy or lower current, or, under general anesthesia, neuromuscular blockade.
A block up to the T10 level is typically required to eliminate discomfort caused by bladder distension during the procedure. Hyperbaric bupivacaine 0.5% is often used in doses of 2.5 to 3.0 mL (12.5 to 15 mg) to reach this level; many providers use less in frail elderly patients, since smaller doses still reach T10 reliably in lithotomy. A block much higher than T10 is best avoided, because it blunts the abdominal pain that announces a perforation and adds hypotension. One notable advantage of spinal anesthesia in TURP is that it minimizes the need for heavy sedation or opioids, which can reduce the risk of postoperative cognitive dysfunction, particularly in elderly patients.
Spinal anesthesia also has hemodynamic implications. While severe hypotension is rare, especially when the patient is in the lithotomy position (which improves venous return), it is important to be vigilant when lowering the legs at the end of the procedure, as hypotension can be unmasked. Vasoconstrictors are the treatment of choice for hypotension in this context, as rapid fluid administration can increase the risk of fluid overload, especially in elderly patients.
General Anesthesia
In some cases, general anesthesia may be preferred, particularly if the patient has contraindications to spinal anesthesia (such as coagulopathy or spinal deformities) or if they cannot tolerate lying supine for an extended period due to respiratory or orthopedic limitations. General anesthesia can also be indicated for patients with persistent cough or anxiety, which may interfere with the surgery.
When general anesthesia is used, airway management becomes a critical consideration, especially in the lithotomy position combined with head-down tilt, which reduces tidal volume and functional residual capacity, increasing the risk of gastric regurgitation. In such cases, tracheal intubation with positive pressure ventilation is preferred, although the use of a laryngeal mask airway with spontaneous ventilation may be acceptable in selected patients. Adequate postoperative analgesia can be provided through single-shot caudal epidural injection of bupivacaine, which offers prolonged pain relief.
One complication under general anesthesia is penile erection, which can interfere with surgery. Deepening the anesthesia level usually resolves this issue. It is also worth noting that monitoring for TURP syndrome can be more challenging under general anesthesia, as the patient’s consciousness is suppressed, necessitating careful monitoring of physiological parameters such as heart rate, blood pressure, and oxygen saturation, and a low threshold for measuring serum sodium during any resection that runs long, bleeds heavily, or shows unexplained hemodynamic change.
| Consideration | Spinal anesthesia | General anesthesia |
|---|---|---|
| When chosen | Technique of choice, especially in elderly patients with compromised respiratory function | Coagulopathy or spinal deformity, inability to lie supine for orthopedic or respiratory reasons, persistent cough or anxiety |
| Block and dose | Block to T10 to eliminate discomfort from bladder distension; bupivacaine 0.5%, 2.5 to 3.0 mL | — |
| Detecting complications | Patient stays conscious and can report periumbilical or shoulder pain suggesting bladder perforation or capsular tear | Consciousness is suppressed, so monitoring leans on heart rate, blood pressure and oxygen saturation; unexplained hypertension then hypotension, bradycardia, hypoxemia or delayed emergence prompt a serum sodium check |
| Airway and ventilation | Avoids the need for heavy sedation | Lithotomy with head-down tilt reduces tidal volume and functional residual capacity and raises regurgitation risk; tracheal intubation with positive pressure ventilation preferred, laryngeal mask with spontaneous ventilation acceptable in selected patients |
| Hemodynamics | Severe hypotension is rare in lithotomy but can be unmasked when the legs are lowered; treat with vasoconstrictors rather than rapid fluid | — |
| Postoperative analgesia | Reduces the need for opioids and sedation, lowering postoperative cognitive dysfunction risk in the elderly | Single-shot caudal epidural bupivacaine gives prolonged relief |
| Technique-specific problem | — | Penile erection interfering with surgery, usually resolved by deepening anesthesia |
