Genitourinary system

Published on 24/02/2015 by admin

Filed under Anesthesiology

Last modified 24/02/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1065 times


Genitourinary system

A Cystectomy

1. Introduction

The bladder is usually removed for cancer but may also be removed for severe hemorrhagic or radiation cystitis. In a radical cystectomy for invasive cancer in women, the uterus, fallopian tubes, ovaries, and a portion of the vaginal wall are removed. In men, the ampulla of the vas deferens, prostate, and seminal vesicles are removed. There is also pelvic lymph node dissection, and a urinary diversion is created (through the intestine).

2. Preoperative assessment

a) Cardiac, respiratory, neurologic, and endocrine systems: Assessment is routine.

b) Renal: Gross hematuria may be a symptom. Check renal function tests as well as evidence of a urinary tract infection.

c) Gastrointestinal: Patients are at risk for fluid and electrolyte imbalance because of bowel preparation.

3. Patient preparation

a) Laboratory tests: Complete blood count, electrolytes, blood urea nitrogen, creatinine, glucose, prothrombin time, partial thromboplastin time, type and screen for 2 to 4 units of blood, and urinalysis

b) Diagnostic tests: Electrocardiography and chest radiography for most of this patient population

c) Medication: Sedation as needed

4. Room preparation

a) Monitors: Standard, arterial line, and central venous pressure; urine output not measurable during this procedure; two large-bore, reliable intravenous (IV) lines available

b) Additional equipment: Epidural insertion and infusion supplies (if using), and warming devices for the patient and fluids

c) Position: Supine

d) Drugs and fluids: 6 to 10 mL/kg/hr of crystalloid for maintenance; 2 to 4 units of blood readily available

5. Perioperative management

Combined general and epidural or general anesthesia with standard induction is used. The patient may be anemic because of hematuria and hypovolemic because of bowel preparation. Attempt to correct these conditions before induction. Maintenance is routine, with special attention paid to fluid calculations and keeping the patient warm. Plan to extubate immediately postoperatively unless the patient is unstable during the procedure or when prior respiratory complications prevent early extubation.

6. Postoperative implications

Epidural or patient-controlled analgesia should be planned for preoperative use. Watch the patient for signs of hypovolemia, anemia, or pulmonary edema resulting from fluid shifts intraoperatively.

B Cystoscopy

1. Introduction

Cystoscopy is the use of instrumentation to examine the urinary tract. A cystoscope may be used for diagnostic or therapeutic procedures such as for workup of hematuria, stricture, and tumor; removal and manipulation of stones; placement of stents; and follow-up of therapy. Retrograde pyelography and other dye studies may be used. This procedure is usually performed on an outpatient basis.

2. Preoperative assessment and patient preparation

a) History and physical examination: Standard

b) Diagnostic tests: Standard

c) Preoperative medication and IV therapy

(1) Prophylactic antibiotics

(2) 18-gauge IV catheter with minimal fluid replacement

3. Room preparation

a) Monitoring equipment: Standard

b) Pharmacologic agents: Indigo carmine, methylene blue

c) Position: Lithotomy

4. Anesthetic technique

The technique of choice is regional blockade or general anesthesia.

a) IV sedation: Midazolam (Versed), fentanyl, or propofol in sedation doses

b) Regional blockade: Analgesia to J10 required

c) General anesthesia: Laryngeal mask airway or oral endotracheal tube

5. Preoperative management

a) Induction: No specific indications

b) Maintenance

(1) Diagnostic dyes may be administered. Use indigo carmine dye (α-sympathomimetic effects) cautiously in patients with hypertension or cardiac ischemia. Methylene blue dye may cause hypertension. Oxygen saturation readings may be altered by dye administration.

(2) Persistent erection may occur in younger male patients, thus preventing manipulation of the cystoscope. Use deeper anesthesia.

(3) Water or irrigation solution may be used to distend the bladder. See the discussion of transurethral resection of the prostate later in this section.

(4) Quadriplegic or paraplegic patients may undergo repeated cystoscopies. Autonomic hyperreflexia is possible if the injury is above level T5.

c) Emergence: No specific indications

6. Postoperative implications

Postoperative care is standard.

C Extracorporeal shock wave lithotripsy

1. Introduction

Extracorporeal shock-wave lithotripsy (ESWL) is a technique that uses high-energy shock waves to fragment renal calculi into small particles. A biplanar fluoroscopy unit is used to focus the shock wave on the target stone. The shock wave is repeated several thousand times and causes the stone to disintegrate. The focused, reflected shock wave passes through the water and enters the body through the flank.

Modern lithotriptors do not require the patient to be submerged in water. Although they do use water for the production of shock waves, a membrane over the shock-wave generator encapsulates the fluid. Transmission of shock waves to the patient is ensured by the use of coupling gel between the patient and the generator membrane.

2. Preoperative assessment and patient preparation

a) Routine preoperative assessment with laboratory tests based on any abnormalities found in the history and physical examination. Consider cardiac status; many hemodynamic changes are associated with this procedure.

b) Absolute contraindications are pregnancy bleeding disorders and abnormal coagulation parameters. Relative contraindications include these active urinary tract infection and a urinary tract obstruction distal to the stone that prevents passage of stone fragments.

c) Relative contraindications include aortic aneurysm, spinal tumors, orthopedic implants in the lumbar region, morbid obesity, AILD (automatic implantable cardioverter-defibrillator), uncontrolled arrhythmias, and coagulation disorders.

d) Ureteral stent placement before ESWL may be used to move the stone upward in the ureter, where it is amenable to therapy.

e) Adequate IV hydration aids in the passage of stone fragments.

f) Prophylactic antibiotics may be given.

g) Electrocardiography, automated cuff measurement of blood pressure, and pulse oximetry are indispensable during lithotripsy.

h) The electrocardiograph must be of good quality because the R wave is used to trigger the shocks. Synchronization of the shock wave to the electrocardiograph has reduced the incidence of cardiac dysrhythmias but has not totally eliminated them. These dysrhythmias are attributed to mechanical stimulation of the heart. Supraventricular premature complexes and premature ventricular complexes are the most common dysrhythmias noted. Atropine or glycopyrrolate may be given to increase the heart rate and thus the shock-wave rate.

3. Anesthetic technique

a) Patient movement: For lithotripsy to be most effective, the stone must remain at the focal point. Because patient movement and patterns of respiration can change kidney and stone position, movement must be minimized and ventilation carefully controlled. The number and intensity of shock waves can be reduced when stone movement is minimized.

b) Anesthetic techniques: Various anesthetic techniques have been used for ESWL. General anesthesia is advantageous because of its rapid onset and control of patient movement. Other techniques include spinal or epidural anesthesia, patient-controlled analgesia, monitored anesthesia care, and topical anesthesia with eutectic local anesthetics. Continuous infusions of propofol, methohexital, ketamine, and alfentanil have been used alone or with midazolam for ESWL anesthesia.

Spinal anesthesia has the advantage of a rapid onset, and a pure opiate spinal using sufentanil is a common technique. Disadvantages include hypotension, spinal headache, and the inability to reinforce the block.

Although epidural anesthesia is associated with a slower onset, hypotension is less, and the block can be reinforced as needed. A dermatomal level of T4 or T6 must be achieved as renal innervation is derived from T10 to L2.

c) Side effects associated with ESWL

(1) Hypothermia, hyperthermia

(2) Cardiac dysrhythmias

(3) Hemorrhagic blisters of skin

(4) Renal edema

(5) Renal hematoma

(6) Lung injury

(7) Flank pain

(8) Hypertension, hypotension

(9) Autonomic hyperreflexia

(10) Nausea, vomiting

(11) Hematuria

(12) External petechia

D Laparoscopic nephrectomy

1. Introduction

Indications for nephrectomy include calculus, hemorrhage, hydronephrosis, hypertension, neoplasms, transplantation, trauma, chronic infection, and vascular disease. Partial nephrectomy is performed to preserve as much renal function as possible. Surgery of the kidney is usually accomplished through a flank incision.

2. Preoperative assessment and patient preparation

a) History and physical examination: Individualized for the patient’s condition

b) Diagnostic tests

(1) IV pyelography with nephrotomography: Identify a renal mass.

(2) Ultrasonography: This differentiates simple cysts from solid tumors.

(3) Arteriography: This determines whether the kidney is suitable for renal transplantation.

(4) Computed tomography

(5) Laboratory tests

(a) Prothrombin time, partial thromboplastin time, complete blood count, electrolytes, and glucose

(b) Glomerular filtration rate: Blood urea nitrogen, plasma creatinine, and creatinine clearance

(c) Renal tubular function: Urine concentration ability, sodium secretion, proteinuria, hematuria urine sediment, and urine volume

c) Preoperative medications and IV therapy

(1) Identify the date of last hemodialysis.

(2) Epidural catheter: Perform a test dose in the preoperative area.

(3) Administer antibiotics.

(4) Use small incremental doses of benzodiazepines to facilitate anxiolysis.

(5) Have a minimum of two peripheral IV tubes (16 to 18 gauge) with moderate fluid replacement.

(6) In patients with renal failure, administer hypotonic solutions: 5% dextrose in water or 5% dextrose and 0.45% saline.

(a) Avoid normal saline: It may increase sodium levels.

(b) Avoid plasmalyte or lactated Ringer’s solution: It may increase potassium levels.

(c) Restrict fluids and consider using microdrip tubing.

3. Room preparation

a) Monitoring equipment

(1) Standard

(2) An arterial line and central venous pressure monitoring may be necessary to trend volume status, especially if the patient is elderly with coexisting medical disease.

(3) A noninvasive blood pressure cuff should not be placed in an arm with an arteriovenous fistula.

b) Pharmacologic agents

(1) Dopamine: Low dose (2–5 mcg/kg/min) to increase urinary output

(2) Furosemide (Lasix), mannitol, or both for stimulation of urinary output

(3) Indigo carmine (hypertension resulting from an α-agonist) or methylene blue (hypotension and interference with the pulse oximeter) administration (IV to assess urinary flow)

(4) Hetastarch (Hespan) or albumin

(5) Heparin and protamine with donor kidneys

c) Position

(1) A lateral decubitus position is used, with the kidney bar raised.

(2) With low calcium levels, skin and nerve damage occur easily.

(3) Inadequate support of the head may lead to Horner syndrome (ptosis, enophthalmos, miosis, and anhidrosis) postoperatively.

(4) Evaluate the radial pulse after placement of an axillary roll.

(5) Respiration is impaired secondary to ventilation–perfusion mismatching, decreased functional reserve capacity, decreased vital capacity, and decreased thoracic compliance.

(6) Reassess breath sounds after movement; an endotracheal tube may migrate into the mainstem bronchus during positioning.

4. Anesthetic technique

a) See the discussion of radical prostatectomy later in this section.

b) Consider rapid-sequence induction because renal patients may be considered to have a full stomach.

5. Perioperative management

a) Induction

(1) Opioids can be used because only a small amount of the drug is excreted unchanged by the kidneys.

(2) Succinylcholine is contraindicated if the potassium is elevated.

(3) Cisatracurium does not require a functional kidney because it is degraded by Hofmann elimination and is a good choice for muscle relaxation. Laudanosine is a metabolite and is associated with seizures. This is not a concern with short-term perioperative use.

(4) Vecuronium and rocuronium may be used for muscle relaxation.

(5) Regardless of blood volume status, renal patients may respond to induction of anesthesia as if they are hypovolemic.

(6) Induction of anesthesia and intubation of the trachea can be safely accomplished with IV drugs plus a nondepolarizing muscle relaxant.

(7) Propofol is highly protein bound, and this may necessitate a reduced dosage. Propofol is exclusively metabolized by the liver, and metabolites are inactive.

(8) Ketamine is less protein bound with less than 3% renal excretion.

(9) Etomidate is 75% protein bound and does not require adjustment.

b) Maintenance

(1) Maintain normal end-tidal carbon dioxide levels.

(2) If working on a donor nephrectomy, the eleventh rib may be removed; pneumothorax is a complication; therefore, nitrous oxide is best avoided.

(3) Maintain urinary output; use medications if necessary.

(4) Inhalation anesthetic is used to control intraoperative hypertension.

c) Emergence

(1) If hypertension occurs on emergence, administer a vasodilator.

(2) Renal patients are considered to have a full stomach; some practitioners require an “awake” patient before extubation.

(3) Initiate regional blockade through the epidural catheter for postoperative analgesia before the end of the case.

6. Postoperative implications

a) Continue to assess volume status.

b) Obtain a chest film. Rule out pulmonary edema and pneumothorax, which may occur after administration of large volumes of fluid in the flank position or from removal of the eleventh rib, respectively.

c) For patients with renal failure, normeperidine, the major metabolite of meperidine, may accumulate and result in prolonged depression of ventilation and seizures.

E Laparoscopic urologic surgery

1. Introduction

Laparoscopy is the process of inspecting the abdominal cavity through an endoscope. Some examples of surgical procedures that can be done laparoscopically include varicocelectomy, percutaneous stone retrieval, nephrectomy, transplants, and radical prostatectomy.

2. Anesthetic technique

Carbon dioxide is used to insufflate the abdominal cavity to facilitate view during this procedure. Several pathophysiologic changes can occur after carbon dioxide pneumoperitoneum and extremes of patient positioning required for the procedure.

Unique problems specific to urologic surgery are listed below.

a) The urogenital system is a retroperitoneal system. As such, carbon dioxide insufflated in this space communicates freely with the thorax and subcutaneous tissue. Subcutaneous emphysema can occur and may extend to the head and neck. In severe cases, it may lead to submucous swelling and airway compromise in the unprotected airway.

b) In long cases, carbon dioxide may not be reabsorbed and acidosis may develop. Because carbon dioxide insufflation coupled with steep Trendelenburg position and long procedures may increase intraabdominal and intrathoracic pressure, controlled ventilation is mandatory.

c) Increased pressure exerted by the insufflation may also affect renal and hepatic function. The pneumoperitoneum can cause renal cortical vasoconstriction because of activation of the sympathetic nervous system. Decreased renal perfusion activates the renin–angiotensin–aldosterone system, which causes vasoconstriction. These effects are additive to those seen with surgical stress. Renal and hepatic perfusion may be altered.

d) Some suggestions to minimize the impact of positive pressure pneumoperitoneum are (1) lowering insufflation pressures, (2) operating in a gasless environment, (3) substituting inert gas for carbon dioxide, (4) using drugs to antagonize the neuroendocrine response, (5) volume expansion, and (6) using mechanical devices. It has been reported that the use of intermittent sequential pneumatic compression activated over the lower limbs 15 minutes after the pneumoperitoneum improves splanchnic and renal perfusion. This technique augments cardiac output and lowers systemic vascular resistance.

F Penile procedures

1. Introduction

Penile procedures are commonly performed for the following three indications: (1) to repair congenital defects such as hypospadias (typically a pediatric procedure), which is usually a pediatric procedure; (2) for penectomy or penile resection as a result of penile cancer; and (3) for implants to compensate for impotence. Organic impotence is often secondary to diabetes, hypertension or side effects from the systemic treatments or spinal cord trauma.

2. Preoperative assessment

Assessment is individualized based on the patient’s condition.

3. Patient preparation

Buy Membership for Anesthesiology Category to continue reading. Learn more here