The role of supraglottic airway devices in obstetric anaesthesia.

PURPOSE OF REVIEW: To discuss the role of supraglottic airway devices as rescue and primary airway devices in pregnant patients. RECENT FINDINGS: General anaesthesia in pregnant patients is associated with increased incidence of difficult and failed intubation, especially when performed for caesarean deliveries. The Difficult Airway Society and the Obstetric Anaesthetists' Association guidelines for the management of failed intubation recommend the use of second-generation supraglottic airway devices as a rescue airway strategy when failed intubation occurs. This practice is now widely accepted and embedded in routine teaching and clinical practice. On the other hand, there is little but growing evidence describing the use of supraglottic airway devices as the primary airway device and an alternative to endotracheal intubation for patients undergoing elective and emergency caesarean deliveries under general anaesthesia. Most of the published research supporting this practice was done on carefully selected patients who were nonobese and who did not have gastroesophageal reflux or anticipated difficult airway. Despite demonstrating high insertion success rates and low complication rates, these studies were underpowered and have thus far, failed to provide robust data on the true risk of aspiration in this setting. SUMMARY: Based on current scientific data, the evidence for the safe use of supraglottic airway devices as primary airway devices during general anaesthesia for caesarean deliveries is not compelling. However, their use as rescue airway devices remains a well established strategy supported by international guidelines.

Peri-intubation oxygenation for Caesarean delivery: is there an optimal technique?

Peri-intubation oxygen administration to the pregnant patient during induction of general anaesthesia is critical to avoiding hypoxaemia and harm to the mother and fetus. Recent modelling comparing low-flow with high-flow nasal oxygen in simulated term pregnant women of varying body habitus, taken together with previous work, suggests that face mask preoxygenation with the use of low-flow or high-flow nasal oxygen during the period of apnoea prolongs the safe apnoea period, with the benefit varying by body habitus. Low-flow compared with high-flow nasal oxygen may be easier to combine with face mask preoxygenation and is readily available in all operating theatres, although future improvements in high-flow nasal oxygen delivery systems may improve ease of use for this indication.

Airway management and training in obstetric anaesthesia.

PURPOSE OF REVIEW: Airway management and failed intubation in the pregnant woman requires unique considerations, which differ from the nonpregnant patient. Factors that influence airway management in this setting include anatomical and physiological changes in pregnancy, environmental factors as well as training matters. In addition, surgery is often being performed with extreme urgency, which requires rapid decision-making process that takes into account safe outcome of mother and baby. The purpose of this review is to focus on recent developments that address these exceptional airway challenges in obstetrics. RECENT FINDINGS: The first national UK obstetric difficult airway guidelines that have been recently published, are based around algorithms that deal with induction of general anaesthesia, failed intubation and front-of-the-neck access. As well as emphasising good practice in planning, preparation, and rapid sequence induction (RSI) technique, they outline how to make a provisional plan prior to the induction of general anaesthesia, on whether to awaken or continue general anaesthesia, should failed intubation occur. Current recommendations aim to move away from the traditional and outdated obstetric RSI technique to introduce changes, which are in keeping with anaesthetic practice in the nonpregnant patients. Such changes include the choice of induction agent and muscle relaxant, preoxygenation techniques, and mask ventilation during RSI; and the early release of cricoid pressure should failed intubation occur. SUMMARY: Recent advances and recommendations in the management of the obstetric airway should help to bring consistency of clinical practice, reduce adverse events, and standardize teaching by providing a structure for teaching and training on failed tracheal intubation in obstetrics. Opportunities during elective caesarean sections and simulation should be used as teaching tools to improve anaesthetists' and team performance during a crisis.

Anesthetic challenges of pregnant obesity women.

Obesity causes significant morbidity and increases the mortality risk for both mother and fetus. With an increasing projected prevalence, it is vital that the obstetric anesthetist is equipped with the knowledge and tools to manage these women. A multi-disciplinary team approach and early planning is required. Neuraxial analgesia for labor helps to negate the need for general anesthesia, which is associated with increased risk in this subset of women. Catheter techniques for neuraxial anesthesia allow for titration, manipulation, and prolongation of the anesthetic block to reduce the risk of conversion to general anesthesia.

Airway management in patients.

Stridor is caused by turbulent flow through a narrow airway. Common causes of stridor are deep neck infection, malignancy, angioneurotic oedema, trauma and congenital anomalies like laryngomalacia. The majority of these conditions can progress rapidly to complete airway obstruction. These conditions are traditionally managed with one of the following techniques: inhalational induction, awake tracheostomy, awake fibreoptic intubation or blind nasal intubation. The success and safety of each of these techniques continues to be debated.

Anaesthetic considerations for hysteroscopic surgery.

Use of the hysteroscope in modern gynaecological practice continues to develop as a diagnostic and management tool for intrauterine disease. Operative hysteroscopy (OH) is now an accepted alternative to hysterectomy for women with menorrhagia. The advantages of OH are associated with its short operating time, rapid post-operative recovery and low morbidity. However, there are concerns about the potential serious complications which can occur during and following OH, and it is important that both surgeons and anaesthetists are aware of these--especially as many procedures take place as day-cases. Much has been written in the urological literature concerning complications of endoscopic surgery. Information gathered from patients with post-transurethral resection of the prostate (TURP) syndrome has been useful in the treatment of gynaecology patients. However, the techniques used in TURP are not entirely comparable to hysteroscopic surgery as the uterus has a very thick wall, which requires higher distension pressures. The main complications of OH are fluid overload, hyponatraemia, hypo-osmolality, haemorrhage, uterine perforation and, rarely, gas or air embolism. Fluid overload with hyponatraemia and hypo-osmolality occurs in up to 6% of cases and it can be fatal. Therefore, all possible measures should be taken to prevent it or to detect it and treat it early. There are no controlled studies comparing different anaesthetic techniques for OH. Regional anaesthesia may offer an advantage over general anaesthesia because it enables early detection of fluid overload. Great care should be taken when positioning the patient to prevent peripheral neuropathy.