To the Editor:-Schaut et al. should be congratulated on their use of inhalation induction with sevoflurane for immediate delivery of a parturient with no accessible veins (Anesthesiology 1997; 86:1392–4). Their quick thinking and quick action resulted in a live, apparently healthy, infant being delivered within 5 min of the patient's arrival in the operating room. Rapid sequence intravenous induction with cricoid pressure followed by endotracheal intubation is the usual standard of care, but in this case, the delay in pursuing this" standard" might have resulted in a brain-damaged infant for which the anesthesiologist could have been blamed.
The authors correctly state that there is a serious risk of maternal morbidity and mortality if aspiration occurs (italics added). The perception among some anesthesiologists is that one would be foolhardy to use a face mask for any obstetric anesthetic and very fortunate if pulmonary aspiration did not occur. But how frequently did aspiration occur before the introduction of rapid sequence induction, cricoid pressure, tracheal intubation, and H2receptor antagonists?
Ether and chloroform, and later cyclopropane, were commonly administered without tracheal intubation for more than 100 yr after Simpson introduced pain relief in childbirth in 1847. Opponents initially criticized the use of anesthesia on medical and moral and religious grounds. One medical opponent went so far as to state that, “In the lying-in chamber … pain is the mother's safety, its absence her destruction.”In response, Simpson collected 800 cases of ether or chloroform administration in childbirth without a death from his own practice and those of colleagues in the British Isles and Europe. His report may have been biased in some aspects, but it seems unlikely that an anesthesia-related death could have escaped publicity.
Almost a century later, in 1946, Mendelson reported 66 cases of pulmonary aspiration of stomach contents in 44,016 pregnancies. Five deaths occurred from aspiration of solid material, but there were no deaths among the 40 parturients who were known to have inhaled liquid and who developed the chest radiograph findings of Mendelson's syndrome. Between 1942 and 1952 in one large English city, there were no anesthetic deaths in 3,048 domiciliary open-drop obstetric anesthetics. At the Women's Hospital in Kathmandu, Nepal in 1982–1983, there was one material death, a result of uncontrollable hemorrhage, among 420 open-drop ether anesthetics given by junior obstetric residents for cesarean section. 
The safety record of the mask or open-drop method may be a result of the fact that vomiting is most likely to occur in light anesthesia during induction or emergence when warning signs of swallowing, breath holding, and salivation allow time for the patient to be turned onto her side. Vomiting does not occur during maintenance of deep inhalational anesthesia (Guedel stage III, plane i or ii). Pulmonary aspiration as an important cause of anesthesia-related maternal death was not emphasized until the 1940s and 1950s by Mendelson and others, but the policy of “mandatory” tracheal intubation, especially when it fails, may actually do harm. [7,9]
When general anesthesia is essential, there are advantages to mother and fetus in the use of tracheal intubation, neuromuscular blockade, and light anesthesia with controlled ventilation. On the other hand, aspiration is sufficiently rare during inhalational anesthesia via face mask that this may be a rational and defensible choice in difficult circumstances. We may do our patients a disservice if we are afraid to use an “obsolete technique” because of exaggeration about its dangers.
J. Roger Maltby, M.B., F.R.C.A., F.R.C.P.C.
Professor of Anaesthesia; Foothills Hospital and the University of Calgary; 1403–29 Street NW; Calgary, Alberta T2N 2T9; Canada