Anesthesia: Surgery For Urological Malignancies: Prostate Cancer

1. Prostate Cancer

Preoperative Considerations

Adenocarcinoma of the prostate is the most com-mon nonskin cancer in men and is second only to lung cancer as the most common cause of cancer deaths in men older than 55 years. Approximately one in six men will be diagnosed with prostate can-cer in their lifetime. Because of the tumor’s wide spectrum of clinical behavior, management varies widely from surveillance to aggressive surgical ther-apy. Important variables include the grade and stage of the malignancy, the patient’s age, and the pres-ence of medical comorbidity. Transrectal ultrasound is used to evaluate tumor size and the presence or absence of extracapsular extension. Clinical stag-ing is also based on the Gleason score of the biopsy, computed tomography (CT) scan or magnetic reso-nance imaging (MRI), and bone scan.

Intraoperative Considerations

Patients with prostate cancer may present to the operating room for laparoscopic or robotic pros-tatectomy with pelvic lymph node dissection, radical retropubic prostatectomy with lymph node dissection, salvage prostatectomy (following failure of radiation therapy), or bilateral orchiectomy for hormonal therapy.

A. Radical Retropubic Prostatectomy

Radical retropubic prostatectomy is usually per-formed with pelvic lymph node dissection through a lower midline abdominal incision. It may be curative for localized prostate cancer or occasionally used as a salvage procedure after failure of radiation. The prostate is removed en bloc with the seminal vesi-cles, ejaculatory ducts, and part of the bladder neck. A “nerve-sparing” technique may be used to help preserve sexual function. Following prostatectomy, the remaining bladder neck is anastomosed directly to the urethra over an indwelling urinary catheter. The surgeon may ask for intravenous administration of indigo carmine for visualization of the ureters, and this dye can be associated with hypertension or hypotensionRadical retropubic prostatectomy may be accompanied by significant operative blood loss.Direct arterial blood pressure monitoring may be utilized. Routine placement of a central venous cath-eter for central venous pressure monitoring and as an additional route for administration of fluid and blood products has also been advocated, although many large cancer treatment centers routinely utilize just two large-bore peripheral intravenous catheters. Operative blood loss varies considerably from center to center, with mean values less than 500 mL com-mon. Factors influencing blood loss include posi-tioning, pelvic anatomy, prostate size, duration of operation, and the skill of the surgeon. Blood loss and operative morbidity and mortality are similar in patients receiving general anesthesia and those receiving regional anesthesia. Neuraxial anesthesia requires a T6 sensory level, but these patients typi-cally do not tolerate regional anesthesia without deep sedation because of the hyperextended supine posi-tion. The combination of a prolonged Trendelenburg position together with administration of large amounts of intravenous fluids may rarely produce edema of the upper airway. The risk of hypothermia should be minimized by utilizing a forced-air warm-ing blanket and an intravenous fluid warmer.

Postoperative complications include hemor-rhage; deep venous thrombosis; pulmonary embolus; injuries to the obturator nerve, ureter, and rectum; and urinary incontinence and impotence. Extensive surgical dissection around the pelvic veins increases the risk of thromboembolic complications. Epidural analgesia is used in some centers following retropu-bic prostatectomy and may improve analgesia and accelerate recovery. Although epidural anesthesia may reduce the incidence of postoperative deep venous thrombosis following open prostatectomy, this beneficial effect may be negated by the routine use of warfarin or fractionated heparin prophylaxis postoperatively. The risk of epidural hematoma in the setting of anticoagulation therapy, particularly with fractionated heparin preparations, must be kept in mind when postoperative epidural analgesia is contemplated. Ketorolac can be used as an analge-sic adjuvant and has been reported to decrease opi-oid requirements, improve analgesia, and promote earlier return of bowel function without increasing transfusion requirements. A multimodal approach to postoperative analgesia is often optimal.

Robot-Assisted Radical Prostatectomy

Laparoscopic radical prostatectomy with pelvic lymph node dissection differs from most other lap-aroscopic procedures by the frequent use of steep (>30°) Trendelenburg position for surgical expo-sure. Patient positioning, duration of procedure, need for abdominal distention, and desirability of increasing minute ventilation necessitate the use of general endotracheal anesthesia. Nitrous oxide is usually avoided to prevent bowel distention. Most laparoscopic prostatectomies are performed with robotic assistance, and the majority of radi-cal prostatectomies in the United States are now performed via robot-assisted laparoscopy. When compared with open retropubic prostatectomy, laparoscopic robot-assisted prostatectomy is asso-ciated with a longer procedure time but may have a lower rate of complications. It is also associated with less blood loss and fewer blood transfusions, lower postoperative pain scores and lower opioid requirements, less postoperative nausea and vomit-ing, and shorter hospital length of stay. The steep Trendelenburg position can lead to head and neck tissue edema and to increased intraocular pres-sure. Complications reported to be associated with such positioning include upper airway edema and postextubation respiratory distress, postoperative visual loss involving ischemic optic neuropathy or retinal detachment, and brachial plexus injury. The surgeon should be routinely advised as to the length of time during which steep Trendelenburg positioning is maintained, and some centers have abandoned the routine use of this positioning entirely.

Most clinicians use a single large-bore intra-venous catheter, and an arterial catheter may be used if clinically indicated. The risk of hypother-mia should be minimized by utilizing a forced-air warming blanket and an intravenous fluid warmer. Adequate postoperative analgesia is provided ini-tially by intravenous opioids with ketorolac and/ or intravenous acetaminophen, and subsequently by oral analgesic preparations. Postoperative epi-dural analgesia is not warranted because of rela-tively low postoperative pain scores and because patients may be discharged less than 36 h after surgery.

C. Bilateral Orchiectomy

Bilateral orchiectomy is usually performed for hormonal control of metastatic adenocarcinoma of the prostate. The procedure is relatively short (20–45 min) and is performed through a single midline scrotal incision. Although bilateral orchiec-tomy can be performed under local anesthesia, most patients and many clinicians prefer general anesthe-sia (usually administered via a laryngeal mask air-way) or spinal anesthesia.