Anesthesia in dysgnathia surgery

30.1 Introduction

The anesthesiologic management of patients for the correction of dysgnathia is characterized by some special features. In principle, these are procedures that can be scheduled, so that thorough diagnosis and treatment of preexisting conditions is not only possible but also mandatory. The patient should be in the best possible condition at the time of surgery.

Another specificity is that here the anesthesiologist’s fields of work intermingle with that of the surgeon – the surgical area is tangential to the patient’s airway in a one-tube system. This results in safety considerations for intra- and postoperative procedures. Impaired ventilation must be avoided in close cooperation with the surgeon and, above all, must be managed quickly if it occurs. This chapter details the requirements for the anesthesia.

30.2 Premedication visit, preliminary examinations, education

Increased incidence of iron deficiency anemia in young women, partly also due to special dietary preferences (vegetarian, vegan), therefore determination of Hb value.
If anemia is present, the cause should be clarified (eg, determination of ferritin, folic acid, and vitamin B12) and the Hb value should be optimized preoperatively, eg by intravenous iron substitution and, if necessary, erythropoietin administration. A concept for the avoidance of foreign blood transfusions (patient blood management) should be established.¹^,²
The medical details regarding intraoperative blood loss must be known, according to which further preparations such as autologous blood donation (with appropriate lead time, at least 1 to 2 weeks per intended collection) or provision of homologous red cell concentrates are made. At the author’s facility, only the blood group is determined, and an antibody screening test performed.
Obtain a thorough coagulation history, including family history.
In otherwise healthy patients, neither further laboratory tests nor a routine ECG or chest X-ray are required from an anesthesiologic point of view. Supplementary examinations are ordered in a targeted manner according to any previous illnesses/examination findings.
Educate the patient about nasal intubation or, if intubation problems are foreseeable, awake fiberoptic intubation with topical anesthesia and analgesia. Arterial cannulation and postoperative intensive care monitoring should be addressed.
Medication on the day of surgery: Continuation of long-term medication (especially statins, beta-blockers, and other cardiovascular drugs). Anxiolysis with benzodiazepines may be helpful in individual cases (eg, midazolam 7.5 mg p.os).
Food restriction: 6 hours for solid food, clear liquid is allowed until 2 hours before induction.³

30.3 Anesthesia induction

Review of the WHO checklist⁴ (Fig 30-1)
Perioperative antibiotics should be administered 30 minutes before incision. Substance: 1st generation cephalosporin, eg Cefazolin. In case of surgery duration over 4 hours or high blood loss, a repeat dose should be administered.
In principle, all common drugs can be used for induction and anesthesia management. Since hypotensive blood pressure values are often desired by the surgeon, volatile anesthetics can be considered (eg, desflurane) to be favorable.
In this patient population, difficult intubations are likely to occur frequently, especially in cases of mandibular retrognathia or malformations with microgeny. Alternatives to conventional airway management must be available, ideally combined in an “airway cart” (Fig 30-2), eg videolaryngoscope, bronchoscope for fiberoptic intubation, and for emergency situations, supraglottic airway (laryngeal mask, laryngeal tube) and coniotomy set.
Standard procedure: Nasotracheal intubation with RAE (Ring, Adair, and Elwyn) tube (Fig 30-3). In this case, the tube may only be advanced through the lower nasal passage when it is clear that the laryngeal inlet can also be visualized laryngoscopically. If this is not the case and fiberoptic intubation becomes necessary, bleeding caused by the tube could obstruct this route.
Accesses: two safe venous cannulas, arterial cannula with online pressure measurement.
Nasogastric tube remains until the morning of the first postoperative day.