Patient Characteristics
Most patients seen in ambulatory surgical facilities are classified
as ASA physical status I or II. However, because of improved anesthesia and surgical
care, increasing numbers of medically stable ASA
physical status III (and even some IV) patients are able to undergo operations away
from conventional medical centers.[2]
In a large,
prospective outcome study by Warner and coworkers,[10]
24% of ambulatory surgical patients were ASA physical status III, and these patients
had a low incidence of morbidity, similar to ASA I and II patients ( Table
68-3
). Other studies have also shown that patients with preexisting medical
conditions do not have an increased incidence of perioperative complications or unexpected
admissions.[47]
This comparable incidence of complications
was attributed to prudent patient selection, careful preoperative evaluation, and
close communication among surgeons, anesthesiologists, and primary care physicians.
The risk of complications can be reduced if preexisting medical
conditions are under good control for at least 3 months before the operation. Therefore,
the ASA physical status should not be considered
in isolation because the type of surgical procedure, the anesthetic technique, and
a multitude of social factors can also influence decisions regarding patient suitability.
[48]
Even morbid obesity (body mass index >35
kg/m2
) is no longer considered an exclusionary criterion for day-case
surgery[49]
; morbidly obese outpatients can be successfully
managed with a facemask for brief procedures.[50]
However, patients with
*A total of four
deaths were reported within 30 days of the surgical procedure (two were related to
motor vehicle accidents).
preexisting cardiovascular (e.g., hypertension, congestive heart failure, angina)
and respiratory (e.g., asthma, chronic obstructive pulmonary disease) conditions,
as well as morbid obesity, had a higher incidence of perioperative morbidity than
did healthy outpatients undergoing similar procedures on an ambulatory basis.[30]
As expected, smoking was associated with an increased risk of respiratory complications
and postoperative would infection in patients undergoing ambulatory surgery.[51]
Interestingly, the presence of obstructive sleep apnea syndrome was not associated
with an increased risk of unanticipated admission to the hospital.[18]
Susceptibility to Malignant Hyperthermia
MH-susceptible patients can be successfully managed with nontriggering
anesthetics (e.g., local anesthesia) in the outpatient setting (see Chapter
29
). The decision to admit a patient postoperatively should be based on
clinical criteria because admission solely on the basis of MH susceptibility is no
longer considered appropriate.[52]
If anesthesia
and surgery have been uneventful, MH-susceptible patients should be observed for
at least 4 hours postoperatively and may then be safely discharged home.[53]
Patients and their families should be advised about the signs and symptoms of MH,
in addition to the usual postoperative instructions.
Extremes of Age
Although the acceptability of patients at the extremes of age
(i.e., <6 months and >70 years) has been questioned, age alone should not be
considered a deterrent in the selection of patients for ambulatory surgery (see Chapter
60
and Chapter 62
).
Many studies have failed to demonstrate an age-related increase in recovery time
or incidence of complications after outpatient anesthesia.[54]
Even the socalled elderly elderly patient (>100 years) should not be denied ambulatory
surgery solely on the basis of age.[55]
In fact,
elderly patients experience less postoperative pain, dizziness, and emetic symptoms
than their younger counterparts.[56]
Nevertheless,
elderly outpatients may experience a higher incidence of perioperative cardiovascular
events, and recovery of fine motor skills and cognitive function is slowed with increasing
age. Therefore, elderly outpatients may require a greater degree of supervision
after discharge than their younger counterparts. Social factors, including lack
of transportation, a responsible escort, or a caretaker at home, may make it difficult
for some elderly patients to undergo ambulatory procedures.
On the other extreme, ex-premature infants (gestational age <37
weeks) recovering from minor surgical procedures under general anesthesia have an
increased risk for postoperative apnea.[57]
Controversy
exists regarding the postconceptual age after which no further risk remains.[58]
Most studies suggest that the risk is greatest in premature infants younger than
46 weeks' postconceptual age.[59]
[60]
However, some authors have reported that the risk of apnea may persist until the
60th postconceptual week.[61]
Anemia (hematocrit
<30%) independently increases the risk of postoperative apnea in former preterm
infants less than 60 weeks' postconceptual age.[62]
Treatment with high-dose caffeine may prevent prolonged apnea and desaturation in
this patient population, but careful postoperative monitoring is still recommended.
[63]
A combined analysis has determined the following:
(1) apnea was strongly and inversely related to both gestational and postconceptual
age; (2) an associated risk factor was continuing apnea at home; (3) infants who
were small for gestational age seemed to be somewhat protected from apnea; (4) anemia
was a significant independent risk factor, particularly for infants less than 43
weeks' postconceptual age; and (5) no relationship exists between apnea and a history
of necrotizing enterocolitis, respiratory distress syndrome, bronchopulmonary dysplasia,
or intraoperative use of opioid analgesics and muscle relaxants.[64]
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