SPECIAL PATIENT GROUPS
Obstetrics
Maternal mortality is rare, and the anesthesia-related component
of maternal delivery represents only a small fraction of all maternal deaths, making
the study of this
TABLE 24-14 -- Factors associated with increased perioperative complications
|
|
Cardiovascular Complications |
Pulmonary Complications |
Mortality in Hospital |
|
Risk Factors |
No. of Anesthetics (n = 7306)
*
|
% |
(odds ratio) |
% |
(odds ratio) |
% |
(odds ratio) |
|
Sex |
|
|
|
|
|
|
|
|
Female |
4587 |
4.9 |
|
3.7 |
|
0.7 |
|
|
Male |
2634 |
8.8
†
|
(1.8) |
6.6
†
|
(1.8) |
2.2
†
|
(3.2) |
|
Age (yr) |
|
|
|
|
|
|
|
|
<50 |
3965 |
2.6 |
|
2.3 |
|
0.3 |
|
|
50–90 |
2043 |
8.2 |
|
6.7 |
|
1.8 |
|
|
70–79 |
886 |
14.3
†
|
|
8.9 |
|
2.9
†
|
|
|
≥80 |
293 |
16.7
†
|
|
10.2
†
|
|
5.8
†
|
|
|
Ischemic heart disease |
103 |
29.1
†
|
(6.5) |
8.7 |
(1.9) |
2.9 |
(2.5) |
|
Myocardial infarction |
|
|
|
|
|
|
|
|
>1 yr |
125 |
20.8
†
|
|
7.7 |
|
4.0
†
|
|
|
≤1 yr |
26 |
38.5
†
|
|
10.4
†
|
|
7.7
†
|
|
|
Chronic heart failure |
199 |
35.2
†
|
|
15.1
†
|
(3.8) |
9.0
†
|
(9.9) |
|
Hypertension |
380 |
11.8
†
|
(2.1) |
7.1
†
|
(1.6) |
1.3 |
(1.1) |
|
Hypertension (SBP ≤90 mm Hg) |
127 |
16.5
†
|
(2.5) |
17.3
†
|
(4.0) |
9.4
†
|
(9.8) |
|
Chronic obstructive lung disease |
201 |
12.4
†
|
(2.1) |
12.4 |
(3.0) |
5.0
†
|
(4.7) |
|
Renal failure |
153 |
14.4
†
|
(2.2) |
11.8
†
|
(2.4) |
5.9
†
|
(5.2) |
|
Diabetes mellitus |
141 |
9.2 |
(1.5) |
7.1 |
(1.5) |
2.1
†
|
(1.8) |
|
Neurologic disease |
34 |
5.9 |
(1.0) |
8.8
†
|
(1.9) |
2.9 |
(2.4) |
|
Cancer |
1257 |
7.0 |
(1.1) |
5.5 |
(1.2) |
1.1 |
(1.0) |
|
Cancer (abdominal) |
242 |
19.8
†
|
(3.2) |
19.4
†
|
(4.3) |
5.0
†
|
(5.4) |
|
Emergency surgery |
2454 |
7.4
†
|
(1.3) |
6.3
†
|
(3.0) |
2.8
†
|
(3.2) |
|
Duration of anesthesia (min) |
|
|
|
|
|
|
|
|
<30 |
1774 |
1.2 |
|
0.6 |
|
0.1 |
|
|
30–179 |
4621 |
6.8 |
|
4.5 |
|
1.3 |
|
|
180–299 |
470 |
17.9
†
|
|
13.4
†
|
|
3.2
†
|
|
|
≥300 |
162 |
20.4
†
|
|
30.2
†
|
|
4.9
†
|
|
|
Minor surgery |
4916 |
3.2 |
|
1.8 |
|
0.3 |
|
|
Major surgery |
2113 |
13.0
†
|
(4.1) |
10.6 |
(5.8) |
3.1
†
|
(4.9) |
|
Total |
|
6.3 |
|
4.8 |
|
1.2 |
|
|
From Pedersen T: Complications and death following
anaesthesia: A prospective study with special reference to the influence of patient-,
anaesthesia-, and surgery-related risk factors. Dan Med Bull 41:319, 1994. |
*The
analysis shows the maximum number of patients in the various groups.
†P
< .05 indicates a statistically significant higher rate of complications and mortality
compared with the rest of the total incidence. SBP, systolic blood pressure.
problem difficult or impossible in any one institution (see Chapter
58
). A series of studies was performed between 1974 and 1985 to determine
the rate of complications in the United States and England. One of the first reports
was for the period of 1974 to 1978. Kaunitz and colleagues[141]
reported an anesthesia-related death rate of 0.6 per 100,000 births using data from
all 50 states. Endler and coworkers[142]
studied
births in Michigan between 1972 and 1984 and reported 15 maternal deaths in which
anesthesia was the primary cause and 4 deaths in which anesthesia was contributory.
This resulted in a rate of 0.82 anesthesia-related deaths per 100,000 live births.
Eleven of the 15 deaths were associated with cesarean section. Obesity and emergency
surgery were risk factors in many patients. Complications related to regional anesthesia
were problems during the early part of the study, whereas failure to secure a patent
airway was the primary cause of mortality in later years. There were no anesthesia-related
maternal deaths in the final 2 years of the study. The incidence of anesthesia-related
death was markedly higher among black women, which the investigators suggested might
have been related to an inability to detect cyanosis. Rochat and colleagues[143]
studied 19 areas of the United States between 1980 and 1985 and reported 0.98 anesthesia-related
deaths per 100,000 live births. They observed that maternal mortality did not decrease
over the time of the study.
The Confidential Enquiry into Maternal Deaths in England and Wales
has been assessing maternal deaths since 1952.[144]
Records of all maternal deaths are sent to a district medical officer, who sends
an inquiry form to all health practitioners involved in the care of those patients.
These forms are evaluated by a senior obstetrician and an anesthesia assessor.
Morgan[144]
reported the maternal deaths from anesthesia
between 1952 and 1981 ( Table 24-15
).
The total maternal mortality rate decreased
TABLE 24-15 -- Maternal mortality figures obtained from the Confidential Enquiry into Maternal
Deaths in England and Wales
|
Years |
Maternal Mortality per 1000
Total Births |
Number of Deaths from Anesthesia |
Percentage of True Maternal
Deaths from Anesthesia |
Percentage with Avoidable Factors* |
|
1952–1954 |
0.53 |
49 |
4.5 |
— |
|
1955–1957 |
0.43 |
31 |
3.6 |
77 |
|
1958–1960 |
0.33 |
30 |
4.0 |
80 |
|
1961–1963 |
0.26 |
28 |
4.0 |
50 |
|
1964–1966 |
0.20 |
50 |
8.7 |
48 |
|
1967–1969 |
0.16 |
50 |
10.9 |
68 |
|
1970–1972 |
0.13 |
37 |
10.4 |
76 |
|
1973–1975 |
0.11 |
31 |
13.2 |
90 |
|
1976–1978 |
0.11 |
30 |
13.2 |
93 |
|
1979–1981 |
0.11 |
22 |
12.2 |
100 |
|
From Morgan M: Anaesthetic contribution to maternal
mortality. Br J Anaesth 59:842, 1987. |
over time, and the percentage of deaths related to anesthesia increased, although
the absolute number of deaths from anesthesia decreased. During the early years
of the study, endotracheal intubation was rarely performed during obstetric anesthesia.
Later reports advocated the use of endotracheal intubation after thiopentone-suxamethonium,
and technical difficulties with intubation were identified. The other major finding
of this study was that the experience of the anesthetist in obstetric anesthesia
was the most important factor in anesthesia-related maternal mortality.
Several studies have attempted to define the cause of anesthesia-related
maternal deaths. Insights into the cause of maternal mortality can also be elicited
from the ACCS. In 1991, Chadwick and colleagues[145]
published a report of closed malpractice claims related to 190 obstetric cases, representing
127 cesarean sections and 63 vaginal deliveries. The most frequent complications
were maternal death and brain damage in the newborn. There were 15 maternal deaths
among patients who had regional anesthesia and 26 among patients who had general
anesthesia. Because the absolute number of patients who underwent each type of anesthesia
was unknown, the risk attributable to
TABLE 24-16 -- Numbers, case-fatality rates, and risk ratios of anesthesia-related deaths
during cesarean section delivery by type of anesthesia in the United States, 1979–1984
and 1985–1990
|
Number of Deaths |
Case-Fatality Rate |
Risk Ratio |
|
Population |
1979–1984 |
1985–1990 |
1979–1984 |
1985–1990 |
1979–1984 |
1985–1990 |
|
General |
33 |
32 |
20.0
*
|
32.3
*
|
2.3 |
16.7 |
|
|
|
(95% CI 17.7,22.7) |
(95% CI 25.9,49.3) |
(95% CI 1.9,2.9) |
(95% CI 12.9,21.8) |
|
Regional |
19 |
9 |
8.6
†
|
1.9
†
|
Referent |
Referent |
|
|
|
(95% CI 1.8,9.4) |
(95% CI 1.8,2.0) |
|
|
|
CI, confidence interval. |
|
Adapted from Hawkins JL, Gibbs CP, Orleans M, et al:
Obstetric anesthesia work force survey, 1981 versus 1992. Anesthesiology 87:135,
1997. |
*Per million
general anesthetics for cesarean section.
†Per
million regional anesthetics for cesarean section.
anesthesia could not be determined, unlike the subsequent report from Hawkins and
coworkers.[148]
Hawkins and coworkers[148]
obtained
data from the ongoing National Pregnancy Mortality Surveillance System of the Centers
for Disease Control and Prevention (CDC). Using state data on births and fetal deaths
from 1979 through 1990, three obstetric anesthesiologists reviewed the records to
determine the possible risk related to anesthesia. A total of 129 women died of
anesthesia-related causes during the study period, most (82%) during cesarean section,
and the incidence decreased over time ( Table
24-16
). The decreased mortality rate appeared to be related to increased
use of regional anesthesia. The primary cause of mortality was related to the type
of anesthesia. For general anesthesia, 73% of the deaths were related to airway
problems. Unlike the Confidential Enquiry into Maternal Deaths in England, the United
States study lacked the extensive detail for each event, and the absolute cause of
mortality therefore remained somewhat in doubt. In particular, the researchers acknowledge
that general anesthesia may be used more often for patients with a higher acuity
of disease, which may account for the higher mortality rate
associated with its use. The availability of national databases should allow accurate
tracking of mortality to ensure that appropriate quality-assurance and quality-improvement
systems are in place.
Panchal and colleagues[146]
conducted
a retrospective case-control study using patients' records from a statemaintained
anonymous database of all nonfederal Maryland hospitals that performed deliveries
between 1984 and 1997 ( Fig. 24-6
).
Variables studied included patient demographics and ICD-9 (Clinical Modification)
diagnosis and procedure codes. Of the 822,591 hospital admissions for delivery during
the 14-year study period, there were 135 maternal deaths. The most common diagnoses
associated with mortality during hospital admission for delivery were preeclampsia
or eclampsia (22.2%); postpartum hemorrhage or obstetric shock (22.2%); pulmonary
complications (14%); blood clot or amniotic embolism, or both (8.1%); and anesthesia-related
complications (5.2%).
Gibbs and coworkers[147]
surveyed
1200 hospitals in 1981 and sent questionnaires to the chiefs of anesthesia and obstetrics.
Anesthesiologists were available for obstetric anesthesia in only 21% of all hospitals
and at night and on the weekends in only 15%. Hospitals with fewer than 500 deliveries
per year had the most striking deficiencies in anesthesia personnel. Even for cases
in which general anesthesia was provided for cesarean section, an anesthesiologist
was involved in the care only 44% of the time, whereas hospitals with greater than
1500 deliveries per year had an anesthesiologist present 85% of the time. The researchers
did not evaluate the relationship between outcome and staffing models. The survey
was performed again in 1992.[148]
Compared with
1981, the researchers found a marked increase in the availability of labor analgesia
and a decrease in the use of general anesthesia. In more than one half of the anesthesia
procedures for cesarean section, care was provided by nurse anesthetists without
medical direction by an anesthesiologist. How these trends in staffing have affected
maternal mortality requires further evaluation.
Figure 24-6
Delivery mortality ratios by race in Maryland, from 1984
to 1997, using discharge summaries. (From Panchal S, Arria AM, Labhsetwar
SA: Maternal mortality during hospital admission for delivery: A retrospective
analysis using a statemaintained database. Anesth Analg 93:134, 2001.)
