Hysterectomy

Hysterectomy may be undertaken by an abdominal or a vaginal route. Abdominal hysterectomy equates to a laparotomy in its anaesthesia requirements, although the use of a low transverse incision has encouraged the use of the laryngeal mask airway instead of endotracheal intubation (assuming no other contraindications, such as morbid obesity). Muscular relaxation and controlled ventilation are usually required, with volatile agent and opioid of choice. Postoperative pain relief may be delivered by the use of epidural infusions or PCA. The combination of PCA with a rectally administered NSAID (such as diclofenac 100 mg) is widespread. Rectal administration of NSAIDs in gynaecological surgery is especially indicated, as the high concentrations of the drug which are found in the pelvic venous plexus after absorption ensure delivery to the surgical field. Vaginal hysterectomy is less of an insult than abdominal hysterectomy but has broadly similar anaesthesia requirements. Caudal injection of local anaesthetic agents provides a degree of postoperative analgesia, although it is unlikely that the level of block from this technique will reach sufficient height to be fully effective (T10); therefore, additional analgesia should be provided. If rectal drug administration after pelvic floor repair is desired, this is best administered by the operating surgeon after completion, when the suppository can be gently inserted without damage to the suture line.

Transcervical resection of endometrium (TCRE) and microwave endometrial ablation (MEA) are replacing hysterectomy as a treatment for uncomplicated menorrhagia. In TCRE a resectoscope is inserted through the cervix, after which endometrium is resected by laser or diathermy under direct vision. Fluid irrigation of the uterus is necessary in this procedure. The irrigating solution is isotonic glycine, and the problems of absorption are identical to those occurring during transurethral resection of the prostate (Figure 6.1). The use of irrigating solutions containing 1% alcohol is recommended, as absorption can be monitored by the measurement of breath alcohol using a suitable meter and normogram tables. TCRE is not accompanied by significant postoperative discomfort. In terms of anaesthetic requirement, MEA varies little from dilatation and curettage (D&C). General anaesthesia with spontaneous ventilation via a face mask or laryngeal mask is therefore adequate.

Laparoscopy

Laparoscopy involves the inflation of the abdomen with carbon dioxide before the insertion of an endoscope to examine the abdominal contents. The degree of inflation of the abdomen varies greatly between surgeons. Although the procedure is possible with the patient breathing spontaneously, this is not recommended, and controlled ventilation with muscular relaxation is the norm (suitable agents being mivacurium and atracurium). Use of the laryngeal mask airway is common but not universal. The procedure is usually of short duration and not accompanied by great postoperative discomfort except in the case of sterilisation or other tubal surgery, where the presence of occluding clips on the Fallopian tubes may precipitate spasm. In this situation opioid drugs may be needed postoperatively, although NSAIDs are a preferred first-line treatment (especially for a day-case patient).

The most alarming problem during laparoscopy is a severe bradycardia which may be precipitated on inflating the abdomen. Vagolytic drugs should be always at hand, and if necessary the abdomen should be deflated until the heart rate stabilises. Asystolic arrest has been reported.

Laparoscopy may be used to confirm the diagnosis of ectopic pregnancy. The patient must be carefully assessed to ensure that there is no great degree of concealed blood loss. The onset of muscle relaxation under anaesthesia in a patient with a bleeding ectopic pregnancy can result in sudden massive haemorrhage, in which case aggressive fluid replacement and urgent laparotomy are required. Large-scale blood replacement should always be followed by haematological assessment of coagulation and appropriate remedial therapy.

Evacuation and termination (ERPC/STOP)

Evacuation of retained products of conception (ERPC) and suction termination of pregnancy (STOP) are similar in their anaesthesia requirements. As the volatile anaesthetic agents have a relaxant effect on the uterus, their use is associated with increased blood loss, although this may not reach clinical significance. For this reason a technique of intermittent (or infused) induction agent is usual. Propofol with or without supplemental opioid is popular for what is a short, minimally disruptive procedure. Patients requiring ERPC should be assessed for preoperative blood loss and resuscitated as necessary. The use of oxytocic agents during anaesthesia for STOP is occasionally accompanied by untoward effects (peripheral vasoconstriction, for example).

Laryngoscopy

Direct laryngoscopy and its variants (which may include the use of lasers in the airway) demand special techniques of airway management because the surgeon works directly in the airway and needs access to the larynx. Specially designed small tracheal tubes, tubes with a cuff and an insufflation port, or special laser-proof tubes are available, and all have their uses. Because of the difficulties of maintaining spontaneous or controlled ventilation under these circumstances, the usual techniques involve a total intravenous technique with controlled ventilation using an insufflation device such as the Sanders injector or high-frequency jet ventilator. If lasers are to be used in the airway then great care must be taken to isolate the trachea below the tube cuff from the airway above the cuff, because any backwash of gas containing oxygen might result in an explosion or fire when the laser is next fired. Nitrous oxide is flammable.

Tonsillectomy

Anaesthesia for tonsillectomy with or without adenoidectomy requires defence of the shared airway from blood and debris. This necessarily involves endotracheal intubation after induction, which may be inhalational or intravenous. If an uncuffed tube is used in the child patient, a suitable pack (ribbon gauze, for example) should be placed around the laryngeal additus to protect the larynx from contamination of blood and saliva. Use of a Boyle–Davis gag will prevent compression of the tube during surgical positioning. Having decided upon intubation, controlled ventilation should be used, and commonly a non-depolarising relaxant, opioid, vapour combination is used for the maintenance of anaesthesia. Extubation should be undertaken in the head-down lateral position after adequate pharyngeal suction. There are two choices for timing of this event: while the patient is still deep, or after protective reflexes have returned. The latter is more common today. Blood loss should be particularly carefully assessed in young children. The potential for transmission of prion disease by surgical and anaesthetic instruments is discussed in Chapter 5.

Post-tonsillectomy haemorrhage is a specific problem that requires mention. Following post-tonsillectomy haemorrhage, the patient will usually be pale, tachycardic and sweaty. Intravenous resuscitation is essential before induction, and two different techniques of anaesthesia have been recommended. In both situations the patient should be placed head-down, in left lateral position, with suction to hand. Following preparation of all equipment a choice may be made between intravenous or gaseous induction. In the first instance after the usual RSI precautions (pre-oxygenation, cricoid pressure) a cautious dose of induction agent is given, followed by suxamethonium and securing the airway by endotracheal intubation. Alternatively, a gaseous induction of vapour and oxygen may be employed, using suction as necessary and enough time to achieve a plane of anaesthesia deep enough to permit laryngoscopy and intubation. Maintenance and extubation are as described above. Some authorities recommend the emptying of swallowed blood from the stomach with a nasogastric tube before extubation, which would appear wise.