OUTCOME MEASURES
As outpatient surgery continues to grow and the types of surgical
procedures become more complex, ambulatory surgical centers must develop methods
to evaluate patient outcome during both the early and late recovery periods (see
Chapter 23
and Chapter
24
).[586]
The overall risk of major morbidity
and mortality is very low after ambulatory surgery. A large, retrospective study
of more than 45,000 ASA I to III outpatients found that only 31 patients (1:1455)
experienced major morbidity.[10]
Four patients
died, two as passengers in automobile accidents within the first 48 hours and two
of myocardial infarctions more than 48 hours after surgery. In 1987, a multicenter
survey involving over 50 freestanding ambulatory centers in the United States found
an increased risk of perioperative complications in patients who had preexisting
cardiovascular diseases and in those undergoing procedures lasting longer than 1
hour.[585]
A four-center prospective study involving
6914 Canadian outpatients also found that patients with underlying medical conditions
(e.g., hypertension, diabetes, and gastrointestinal disorders) were at higher risk
for adverse events in the perioperative period, even if they were optimally managed
preoperatively.[587]
No deaths occurred during
the study period, and major morbid events were rare.
Although the incidence of major morbidity is low, minor complications
remain problematic after ambulatory surgery, in particular, in the postdischarge
period." In a survey of anesthesiologists,[588]
the clinical anesthesia outcomes that were thought to be most important to avoid
in the ambulatory setting were incisional pain, nausea, vomiting, preoperative anxiety,
and discomfort from insertion of the intravenous line. One study found that 35%
of outpatients discharged from ambulatory surgical centers experienced PONV severe
enough to prevent their return to normal daily activities.[589]
Half these patients had not experienced PONV in the recovery room and became symptomatic
only after discharge home. Incisional pain, PONV, drowsiness, dizziness, headache,
and fever are the most frequent minor symptoms that occur after surgical outpatients
are discharged home.[590]
The type of surgical
procedure also influences the incidence of symptoms, with laparoscopic, general,
and orthopedic surgical procedures having the highest incidence and minor gynecologic
and ophthalmologic procedures having the lowest incidence of postdischarge symptoms.
As with PONV, patients experiencing other postoperative symptoms had a delay in
returning to their usual daily activities. Despite the frequent occurrence of minor
morbidity after ambulatory surgery, patient satisfaction is remarkably high, and
most would again choose to have their surgery performed on an outpatient basis in
the future.[9]
Unexpected hospital admission after outpatient surgery is an easily
identifiable outcome measure after ambulatory anesthesia. Not only does hospital
admission add to the expense of the procedure, but it is also disruptive for the
patient and the surgical facility. Most ambulatory surgery facilities have admission
rates of less than 1%.[11]
[12]
[13]
[14]
Orthopedic
(3.2%), general surgery (3.1%), otolaryngology (3.1%), and urology (29%) have the
highest rate of unanticipated admissions.[17]
However,
freestanding and office-based units tend to have lower unanticipated hospital admission
rates than hospital-based ambulatory surgery units do, possibly because of the relative
ease of admission of the latter or a difference in the criteria for selection of
patients or procedures.[12]
The most common causes
for unexpected admission are pain, bleeding, intractable vomiting, surgical misadventure
(e.g., bowel or uterine perforation), more extensive surgery, urinary retention,
or lack of an escort.[11]
The likelihood of an unexpected hospital admission is related
more to the type of surgery performed than to specific patient characteristics or
the choice of anesthetic technique. The frequency of return hospital visits after
discharge from ambulatory units is another useful outcome measure. One published
study found that 3% of patients returned to the hospital after discharge following
ambulatory surgery.[13]
Bleeding at the surgical
site was the most common reason (42%) for patients to seek emergency medical attention.
Interestingly, patients undergoing varicocelectomy and hydrocelectomy were eight
times more likely to return to the hospital, and most commonly, an infection at the
surgical site was the reason for admission. Most outpatients (77%) who sought medical
attention in the emergency room were treated and subsequently discharged home, a
finding indicating that better preoperative and postoperative education may have
prevented a return visit to the hospital.
