Anesthetic Implications of Hysteroscopy

Devanand Mangar

Enrico M. Camporesi

Hysteroscopy is one of the most commonly performed surgical procedures in women complaining of abnormal uterine bleeding. The operation is performed through a hysteroscope for both diagnostic and therapeutic reasons. In cases where endometrial ablation is performed or uterine leiomyomas are resected, thermal devices such as lasers and electrosurgical energy are used to control bleeding. Continuous irrigation is used to distend the uterus, thereby facilitating surgical visualization, and to wash away operative debris. Hysteroscopy carries the potential for unique complications because of the large volumes of irrigating fluids needed during endoscopic resection. Since uterine vessels are opened during this procedure, there is the possibility of substantial intravenous absorption of fluid via these opened vessels. Therefore, fluid can be absorbed by a mechanism similar to that occurring during transurethral prostatectomy. Irrigating substances include Hyskon, sorbitol, glycine, and mannitol. Systemic absorption of the nonelectrolyte irrigating fluid can produce circulatory overload, hyponatremia, hypoproteinemia, and the presence of the irrigating solute in the circulation. Cases of coagulopathy, pulmonary edema, hyponatremic encephalopathy, and anaphylaxis have been reported as a result of rapid intravascular absorption of the distending medium (see Chapter 27).

The choice of anesthesia administered depends on the past medical history of the patient and on the expertise of the anesthesiologist, as well as on the severity of the patient’s illness. Both regional (spinal or epidural) and general anesthesia can be safely administered to the patient, if she is appropriately monitored.

Choice of Anesthesia

Anesthesiologists have debated for years whether regional anesthesia is better than general anesthesia for patients with cardiac diseases. However, studies comparing the two modalities of anesthesia have produced no definitive answers.

Regional Anesthesia versus General Anesthesia

The main cardiovascular actions of regional anesthesia include vasodilatation in the organs and tissues below the level of the sympathetic block (usually higher than the sensory block), which is partially compensated by vasoconstriction in that part of the body above the level of the sympathetic block. These vascular changes occur in both arterial and venous vasculature and may lead to different degrees of reduction in preload and afterload, resulting in hypotension. Regional anesthesia may result in different degrees of diminished heart rate, as well as myocardial contractility. In patients with mild angina, the reduction in afterload may result in improvement in regional wall motion abnormalities. However, these improvements may disappear with volume loading and probably with infusion of vasoconstrictors. Regional anesthesia also may improve left ventricular loading conditions; however, the concomitant reduction in coronary perfusion pressure can offset this advantage. In rare circumstances, the sympathetic blockade may include T1 to T4 segments and is associated with significant decrease in heart rate because of blocking of the cardioaccelerator fibers. High regional anesthesia with hypotension is associated with decrease in coronary blood flow and decreased myocardial oxygen consumption in healthy humans. Circulatory collapse and death may result if such a decrease occurs in patients with coronary artery disease. Midthoracic epidural anesthesia may have no significant effect on lung volumes or other parameters or may decrease vital capacity, total lung capacity, and forced expiratory volume one (FEV₁). Effective anesthesia and analgesia will prevent pulmonary dysfunction induced by the surgical procedure and pain compared with general anesthesia. In addition, regional anesthesia decreases the stress response in patients with cardiac disease that may be detrimental to cardiovascular function. Most patients can tolerate regional and general anesthesia. Many patients can benefit from regional anesthesia by a decrease in thromboembolism. However, the very sick patient might benefit from general anesthesia because the tight airway control allows attention to be diverted to the more important hemodynamic care of the patient.

When irrigation fluid enters the intravascular space, transurethral resection of the prostate (TURP) syndrome and hysteroscopy syndrome can arise. These dangerous
complications, which have been reported after transurethral resection of the prostate and after endometrial ablation, affect multiple systems and manifest themselves mainly through acute changes in intravascular volume and plasma solute concentrations. Unlike TURP syndrome, hysteroscopy syndrome bears a consistent relation between the volume of fluid absorbed and the duration of hysteroscopy. Since the distending medium is administered under pressure, the irrigating fluid gains access to the circulation via the open venous plexus in the uterus.

Distension Media

The choice of distention media is dependent on the type of procedure and the patient’s condition. Distention can be accomplished by insufflation with carbon dioxide (CO₂) gas or by instillation of an electrolytic or nonelectrolytic fluid. Fluids can be used for both diagnostic and operative procedures. Although CO₂ is a useful distention media, it does not allow the clearing of blood and debris during the procedure. Complications may arise from gas embolism.

Electrolytic solutions include normal saline and lactated Ringer. In 2000, the American Association of Gynecologic Laparoscopists (AAGL) recommended the use of these electrolyte-containing fluids in diagnostic cases and in operative cases in which mechanical, laser, or bipolar energy is used. Because they are capable of conducting electricity, these fluids should not be used in conjunction with monopolar electrosurgical devices. Nonelectrolytic solutions eliminate problems with electrical conductivity, but can increase the risk to patients for hyponatremia and other complications. These solutions include glucose, glycine, dextran, mannitol, sorbitol, and a mannitol/sorbitol mixture (Purisol). Until the late 1980s, water was included in this list; however, problems with water intoxication and hemolysis caused its use to be discontinued. Each of these distention fluids is associated with different physiologic changes that should be considered when selecting a distention fluid. Glucose is contraindicated in patients with glucose intolerance. Sorbitol metabolizes to fructose in the liver and is contraindicated in patients with fructose intolerance. Dextran complications can be physiologic and mechanical. It can crystallize on instruments and obstruct the valves and channels. Patient complications include coagulation disorders, allergic reactions, and adult respiratory distress syndrome (ARDS).

Glycine metabolizes into ammonia and can cross the blood–brain barrier, causing agitation, dizziness, vomiting, and coma. It may also cause a transient decrease in visual acuity. The AAGL recommends the use of mannitol instead of glycine or sorbitol when using monopolar electrosurgery.

Mannitol 5% has a diuretic effect and has caused circulatory disturbances, hypotension, and circulatory collapse. When mannitol is combined with sorbitol, the mannitol/ sorbitol mixture (Purisol) should not be used in fructose-intolerant patients.

Absorption of irrigating solutions, resulting in fluid overload, is a well-known and severe complication of ablative hysteroscopy; the incidence rate is from 3% to 6%. Vascular uptake of irrigating fluid depends on various factors. Surgical skills and the nature of the operation are considered key factors. Fluid absorption correlates with the surface area of the surgical field, opened venous channels, duration of the procedure, chemophysical characteristics of the distending medium, and pressure produced by the delivery system. Because rapid absorption of irrigation fluids during operative hysteroscopy cannot be completely prevented, careful perioperative monitoring of hysteroscopic fluid management is paramount, and abnormalities of fluid balance must be treated. An awake patient may be the best monitor for early detection of excessive fluid absorption. Therefore, regional anesthesia offers a distinct advantage over general anesthesia. When early signs (i.e., apprehension, disorientation, nausea, and visual disturbances) of excessive fluid absorption are suspected, interruption of the procedure must be considered. The safety of the patient should never he jeopardized, and steps should be taken to reduce the risk of fluid overload. Uterine perforation is the most frequent complication of hysteroscopy (14.2 occurrences per 1,000 cases) and usually does not necessitate intervention.

Cardiac Reaction

Intravascular volume expansion can be rapid, especially if the irrigating fluid is 3% sorbitol, lactated Ringer, 5% mannitol, or 1.5% glycine. If the substance used is Hyskon, every 100 mL will expand the plasma volume by about 640 mL. Patients with poor left ventricular function will develop pulmonary edema because of acute circulatory volume overload. In addition, antidiuretic hormone produced by the stress of surgery, increased renin, and increased aldosterone activity contribute to volume expansion by promoting water retention. In patients with normal cardiac function, the initial presentation of hypervolemia will be manifested by hypertension and tachycardia, followed by hypotension as further deterioration in cardiac function ensues. When the rate of the irrigating fluid absorption is slowed, flow from the plasma to the interstitium will occur, resulting in a decrease in central venous pressure. The patient will suddenly become hypotensive; this is especially seen in those patients with normal cardiac function. Sympathetic blockade induced by regional anesthesia will further compound this hysteroscopy syndrome.

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