We are indebted to Sir James Y. Simpson, the discoverer of chloroform, for the introduction of anaesthesia into obstetrical practice. He employed ether for this purpose in 1847, and replaced it by chloroform. Every one agrees as to the marked benefits derived from anaesthesia when operative procedures are to be undertaken, but there is still considerable difference of opinion as to the advisability of its routine employment in normal labour.
—J. Whitridge Williams (1903)
As cited by Williams, anesthetic techniques were a most welcome addition to obstetrics. That said, obstetrical anesthesia presents unique challenges. Labor begins without warning, and anesthesia may be required within minutes of a full meal. Vomiting with potential aspiration of the gastric contents is a constant threat due to delayed gastric emptying during pregnancy. Disorders of pregnancy such as preeclampsia, placental abruption, or sepsis further compound provision of obstetrical anesthesia.
Of all anesthesia-related deaths in the United States from 1995 to 2005, 3.6 percent were in pregnant women (Li, 2009). Creanga and colleagues (2017) analyzed deaths of women during or within 1 year of pregnancy in the United States from 2011 through 2013. Of these deaths, they found that 3 of 2009 (0.2 percent) were attributable to anesthesia complications. As shown in Table 25-1, between 1979 and 2002, anesthesia-related maternal mortality rates decreased nearly 60 percent, and currently approximately five deaths per million live births are attributed to anesthesia complications.
TABLE 25-1Case-Fatality Rates and Rate Ratios of Anesthesia-Related Deaths During Cesarean Delivery by Type of Anesthesia in the United States, 1979–2002 ||Download (.pdf) TABLE 25-1 Case-Fatality Rates and Rate Ratios of Anesthesia-Related Deaths During Cesarean Delivery by Type of Anesthesia in the United States, 1979–2002
| ||Case-Fatality Ratesa || |
|Year ||General ||Regional ||Rate Ratios |
|1979–1984 ||20.0 ||8.6 ||2.3 (95% CI 1.9–2.9) |
|1985–1990 ||32.3 ||1.9 ||16.7 (95% CI 12.9–21.8) |
|1991–1996 ||16.8 ||2.5 ||6.7 (95% CI 3.0–14.9) |
|1997–2002 ||6.5 ||3.8 ||1.7 (95% CI 0–4.6) |
About two thirds of deaths associated with general anesthesia are caused by intubation failure or induction problems during cesarean delivery. Deaths associated with regional analgesia are caused by high spinal or epidural blocks—26 percent; respiratory failure—19 percent; and drug reaction—19 percent. The improved case-fatality rate for general anesthesia is especially notable considering that such anesthesia is now used for the highest-risk patients and the most hurried emergencies, that is, decision-to-incision intervals <15 minutes (Bloom, 2005).
The most significant factor linked to lower maternal mortality rates is the greater use of regional analgesia (Hawkins, 2011). In-house anesthesia coverage that is available around the clock is certainly another contributing factor. Logically, with increased use of regional analgesia, there are now reports of complications with these techniques. Indeed, compared to pre-1990 data, ...