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Anesthetic Techniques for Pharyngeal Flap Surgery
Effects on Postoperative Complications
Meir Bennun, MD;
Bernardo Goldstein, MD;
Edna Zohar, MD;
Yehuda Finkelstein, MD;
Robert Jedeikin, BSc, MB, ChB, FFA(SA);
Brian Fredman, MB, BCh
Arch Otolaryngol Head Neck Surg. 2002;128:35-39.
ABSTRACT
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Objective To assess the effects of 2 different anesthetic techniques on early
complications after superior pharyngeal flap surgery.
Design Randomized, prospective, single-blind study.
Setting Large referral hospital.
Patients One hundred patients undergoing superior pharyngeal flap surgery for
the correction of velopharyngeal insufficiency were randomly divided into
2 equal groups to receive either isoflurane or propofol-based anesthesia.
Interventions Following induction of anesthesia with fentanyl citrate and propofol,
patients were randomized to receive either isoflurane or propofol for the
maintenance of general anesthesia. The inspired isoflurane concentration and
propofol infusion rate were adjusted to maintain a stable depth of anesthesia
as judged by clinical signs and hemodynamic responses to surgical stimuli.
Main Outcome Measures Recovery from anesthesia, recovery from surgery, and early postoperative
complications.
Results The groups were similar in age, weight, height, induction time, surgery
time, extubation time, and anesthetic time. The time (mean ± SD) required
to achieve a maximal Steward Recovery Score was 7 ± 14 minutes in the
propofol group compared with 32 ± 28 minutes in the isoflurane group
(P<.04). No significant differences in postoperative patient
satisfaction scores, time to first swallow, drinking time, and time to "home
readiness" were noted. Overall, 17 patients (17%) developed airway-related
complications and 2 of the patients (2%) were accounted as severe. Two patients
(2%) bled from the operation site. However, there was no difference in the
incidence of postoperative complications between the groups.
Conclusions When compared with isoflurane administration for maintenance of general
anesthesia, propofol-based anesthesia was associated with more rapid mental
and psychomotor recovery. However, airway-related complications and "home
readiness" were similar between the groups.
INTRODUCTION
A SUPERIOR pharyngeal flap is commonly created to treat velopharyngeal
insufficiency.1-2 However, this
procedure is not without complications. Since the upper airway is the site
of surgery, postoperative bleeding and tissue edema may severely compromise
patient safety.3-4 While advances
in surgical technique have decreased the incidence of surgically induced postoperative
complications,5 residual anesthesia during
the immediate postoperative period may reduce nasopharyngeal muscular tone,
depress the cough and swallowing reflexes, and further compromise an already
problematic airway.
While potent inhalational agents isoflurane, halothane, and enflurane
are easy to administer, they impair ventilatory drive in a dose-dependent
manner.6 Furthermore, recovery of mental and
psychomotor function as well as nasopharyngeal reflexes may be delayed.7-9 By contrast, the intravenous
anesthetic agent propofol has been associated with rapid recovery of both
psychomental function and nasopharyngeal reflexes.9-11
Following pharyngeal flap surgery, early return of mental and psychomotor
function as well as nasopharyngeal reflexes may reduce postoperative complications
and length of hospital stay. However, there are no data on the influence of
different anesthetic techniques on early recovery and complications after
pharyngeal flap surgery. Therefore, we designed this randomized, parallel,
single-blind study to compare 2 different anesthetic techniques (inhalational
anesthesia vs propofol-based anesthesia) in patients undergoing superior pharyngeal
flap surgery.
PATIENTS AND METHODS
One hundred consecutive patients (American Society of Anesthesiologists
class I or II) undergoing superior pharyngeal flap surgery for the correction
of velopharyngeal incompetence were studied according to an institutional
review board–approved prospective, randomized, single-blind study protocol.
In all cases, written informed consent was obtained. Patients with a history
of recent respiratory tract infection and clinically significant cardiovascular,
pulmonary, hematological, hepatic, renal, neurologic, psychiatric, or metabolic
disease were excluded from the study. A research assistant, blinded to the
patient randomization, collected all perioperative data. No preanesthetic
medication was administered and all patients were operated on by the same
surgeon.
Upon arrival in the operating room, monitoring equipment was applied
and noninvasive blood pressure, electrocardiogram, and arterial hemoglobin
oxygen saturation were recorded at 1- to 5-minute intervals throughout the
operation. Thereafter, dexamethasone (10 mg) and second-generation cephalosporin
antibiotics were administered intravenously.
Anesthesia was induced intravenously with fentanyl citrate, 3 µg/kg,
and propofol, 2 mg/kg, in all patients. Tracheal intubation and surgical relaxation
was facilitated (using a peripheral nerve stimulator) with an intravenous
atracurium. Following tracheal intubation, the lungs were artificially ventilated
to maintain the end-tidal carbon dioxide at 32 to 36 mm Hg. Thereafter, patients
were randomized to 1 of 2 treatment groups. In the isoflurane group, anesthesia
was maintained with 0.5% to 1.2% isoflurane (end-tidal) and 70% nitrous oxide
in oxygen. In the propofol group, anesthesia was maintained with propofol
infusion, 6 to 8 mg/kg per hour via a syringe pump and 70% nitrous oxide in
oxygen. Any increase in mean arterial pressure or heart rate exceeding 20%
of the patient's preinduction "baseline" values was treated by an increase
in the inspired isoflurane concentration or propofol infusion rate. Following
induction of anesthesia, 10 mL of 2% lidocaine (with adrenaline 1:100 000)
was infiltrated into the soft palate and pharyngeal mucous membrane where
the pharyngeal flap was to be elevated.
Upon completion of the surgical procedure, complete neuromuscular recovery
was confirmed by equal contractions in train of four stimulation with a peripheral
nerve stimulator applied on the ulnar nerve. Residual neuromuscular block
was reversed with neostigmine methylsulfate, 40 µg/kg, and atropine
sulfate, 20 µg/kg, intravenously when necessary, and the maintenance
of anesthetics discontinued. Thereafter, the lungs were ventilated with 100%
oxygen at a flow rate of 8 L/min until tracheal extubation.
During the perioperative period, the following times were recorded:
induction time (the time interval between placing the face mask and start
of surgery), extubation time (the time interval between end of surgery and
extubation), anesthesia time (the time interval between induction of anesthesia
and extubation), and surgical time (the time from the start of surgery until
removal of the surgical mouth-gag).
Patient satisfaction was measured using a 2-sided Faces Rating Scale.12On one side, graphically presented were 5 faces rated
as "Face 0" indicating very happy and "Face 5," crying. On the reverse side,
a 100-mm scale was presented. In children aged 3 to 15 years, the graphic
side was used but translated into millimeters for data recorded. In patients
older than 15 years, a 100-mm visual analog scale was used, where 0 indicated
very happy and 100 the worst imaginable feeling. Measurements were recorded
on arrival to the operating room (baseline), after the operation, and at discharge
from the postanesthetic care unit (PACU).
Using the Steward Recovery Score (SRS),13the
research assistant assessed patient recovery on PACU admission and at 15-minute
intervals until an SRS of 6 was recorded. Time to total recovery was defined
as the time from extubation until patients achieved an SRS of 6. Due to institutional
policy, all patients remained in the PACU for at least 1 hour postoperatively.
During the immediate postoperative period and hourly until hospital
discharge, the incidence of nausea, vomiting, oral bleeding, drooling, and
upper airway obstruction (snoring, stridor, lingual edema, and nasopharyngeal
obstruction) was recorded. Similarly, at the same time intervals, swallowing
time (time from extubation to swallowing secretions), drinking time (time
from extubation to oral fluid intake), and time to "home readiness" (time
from extubation to eating) were noted. Postoperative pain was measured by
a verbal pain rating scale (0 = no pain, 1 = mild, 2 = moderate, 3 = severe
pain). Postoperative analgesia was provided by 20 mg/kg of paracetamol syrup
or suppositories. The number of analgesic requirements was recorded.
Based on the results of previous studies,14-15
a power analysis ( = .05, ß = .8) revealed that 50 patients per
group would be required to detect a 12- to 15-minute difference in the times
from discontinuation of anesthesia to achieving PACU discharge (SRS of 6).
Data are expressed as mean values ± SD. In all cases, normality
was assessed with the Kolmogorov-Smirnov test (using the Lilliefors modification).
Depending upon the results of the Kolmogorov-Smirnov test, either parametric
or nonparametric analyses were performed. Demographic data, patient satisfaction
scores, and postoperative analgesic requirements were analyzed and compared
using the unpaired t test. The SRS, postoperative
pain scores, and the incidence of postoperative complications were compared
using the Fisher exact test or  2 test as appropriate. Swallowing
time and time to home readiness were analyzed using the Mann-Whitney test. P<.05 was considered statistically significant.
RESULTS
The 2 study groups were similar in age, weight, and height. The number
of patients who underwent pharyngeal flap surgery alone or in combination
with tonsillectomy was similar between the groups (Table 1). The syndromes and anomalies associated with the patients
are depicted in Table 2.
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Table 1. Patient Characteristics
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Table 2. Associated Anomalies and Syndromes
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Induction time, surgery time, extubation time, and anesthetic time were
unaffected by patient randomization (Table
3). The time required to achieve a maximal SRS was significantly
shorter in the propofol group (7 ± 14.7 minutes) compared with the
isoflurane group (32 ± 28 minutes) (P<.04)
(Table 3).
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Table 3. Anesthetic and Recovery Times*
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Baseline patient satisfaction scores were similar in both groups (Figure 1). Although patient satisfaction
scores increased significantly from the baseline after the operation and on
discharge from the PACU, there was no difference between the 2 groups (Figure 1).
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Patient satisfaction scores (PSS) increased significantly from the
baseline values after the operation and at postanesthetic care unit (PACU)
discharge. All values are mean ± SEM. The asterisk indicates P<.001; dagger, P = .01.
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No difference in time to first swallow was noted (9.0 ± 7.7 hours
vs 11.0 ± 8.0 hours for the propofol and isoflurane groups, respectively)
(Table 3). Similarly, drinking
time and time to home readiness were unaffected by the group affiliation (Table 3). Postoperative pain scores and
postoperative analgesic requirement were comparable between the groups (Table 4).
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Table 4. Postoperative Pain and Analgesic Requirement*
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The incidence of postoperative nausea, vomiting, bleeding, and drooling
were similar between the groups (Table 5). Upper airway obstruction due to snoring, stridor, lingual edema,
and nasopharyngeal obstruction were similarly comparable (Table 5).
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Table 5. Postoperative Complications*
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COMMENT
Following the surgical creation of a superior pharyngeal flap, depressed
ventilatory and nasopharyngeal reflexes due to residual anesthesia may have
life-threatening consequences.3, 5
Thus, we hypothesized that in the context of upper airway surgery, propofol-based
anesthesia may have benefit over inhalation anesthesia. The results of this
single-blind study suggest that when compared with inhalational anesthesia
with isoflurane, propofol-induced and -maintained general anesthesia is associated
with faster psychomotor recovery. However, following the surgical creation
of a superior pharyngeal flap, propofol-based anesthesia did not decrease
the incidence of postoperative complications. This is supported by the fact
that the time required to achieve a maximal SRS was significantly shorter
in the propofol group. However, extubation time and the time to first swallow
were comparable between the groups. Similarly, the incidence of postoperative
nausea, vomiting, drooling, bleeding, and airway obstruction were unaffected
by the treatment modality. Patient satisfaction scores, although significantly
increased after the operation, were not affected by the type of anesthesia.
Finally, drinking time and time to home readiness were similar between the
groups.
While the time required to achieve maximal SRS was significantly shorter
in the propofol group, the clinical importance of this finding is unclear.
An end-tidal isoflurane concentration as low as 0.22% can delay early recovery
from anesthesia and therefore may contribute to surgically related complications.16 Indeed, in a study that compared 4 different palatoplasty
techniques, one third of the patients became hypoxemic after the operation
and anesthesia was considered as an important cause.17
In our opinion, following pharyngeal flap surgery, surgically related acute
airway compromise is of greater clinical significance than the time required
to achieve a maximal SRS. Since isoflurane-based anesthesia was not associated
with an increased complication rate, the results of our study suggest that
following pharyngeal flap surgery, propofol offers no real advantage compared
with isoflurane. Furthermore, since acute airway compromise is unpredictable,
relatively frequent, and may be life threatening, pharyngeal flap surgery
is unsuitable for "fast-tracking." In addition, due to institutional policy,
all patients recovering from upper airway surgery must remain in the PACU
for at least 1 hour postoperatively. Thus, we suggest that isoflurane is a
safe alternative to propofol for pharyngeal flap surgery.
The results of this study demonstrate that superior pharyngeal flap
surgery is associated with a high incidence of postoperative nausea and vomiting
(28% vs 44% and 40% vs 48% for the propofol and isoflurane groups, respectively).
However, no statistically significant difference was demonstrated between
the groups. While both the high incidence of emetic sequelae and the lack
of statistical significance are difficult to explain, the etiology of these
findings is likely multifactorial. First, pediatric patients are prone to
postoperative nausea and vomiting.18-19
Second, all patients received nitrous oxide. Third, tonsilloadenoidectomy
is associated with increased postoperative emesis.20
Fourth, we hypothesize that following pharyngeal flap surgery, gastric dilatation
due to blood accumulation in the stomach initiates vagal stimulation of the
emetic center of the parvicellular reticular formation. Finally, propofol
anesthesia was surprisingly associated with a marginal but statistically nonsignificant
decrease in postoperative emetic sequelae. While the antiemetic properties
of propofol administration have been well described,9, 20
the results of our study suggest that following pharyngeal flap surgery, stimulation
of the chemoreceptor trigger zone and emetic center are more powerful than
the antiemetic properties of propofol. Since the complex act of vomiting involves
coordination of the respiratory, gastrointestinal, and abdominal musculature,
patients recovering from upper airway surgery are at particular risk for aspiration.
Furthermore, the active straining of retching and vomiting may jeopardize
the flap and surgical reconstruction, which will result in more bleeding and
failure to achieve good operative results. Therefore, to avoid emetic-related
complications following pharyngeal flap surgery, the efficacy of other antiemetic
modalities should be investigated.
Patients are at greater risk for complications during the early postoperative
period. Acute airway obstruction is the most fearful complication and can
occur in 10% to 95% of patients depending on the study being evaluated.21-23 It is precipitated
by edema and swelling of the palate and the tongue caused by the surgical
dissection and the mouth-gag. Opiate or benzodiazepine premedication, anesthesia,
and opiate-based postoperative analgesics can further compromise the impaired
airway by central nervous system depression.17
Airway obstruction may appear as mild snoring, managed by change in patient
position or obstructive sleep apnea requiring oropharyngeal airway insertion.
Because of the severity of the complication, placement of a nasopharyngeal
tube after surgery to maintain nasal airway and admission to a critical care
unit is not an uncommon routine.5, 21
Factors that can predict airway obstruction include the surgeon involved,
the patient's associated medical condition, and the patient's age,5 with the first being the most predictive. In our study,
all of the patients were operated on by the same surgeon and only 2 patients
(2%) experienced severe nasopharyngeal obstruction that required immediate
intervention. In 1 case, the flap obstructed the nasal airway and was treated
by urgent surgery and release of sutures. The second patient had postextubation
glossoptosis and was treated by an oral airway and jaw thrust. The rest of
the patients experienced mild airway incompetence such as stridor, snoring,
and lingual edema; they either recovered spontaneously or after treatment
with corticosteroids. It should be noted that with appropriate surgery, patients
were not required to be admitted to the critical care unit and were discharged
from the hospital in approximately 24 hours after the operation.
Bleeding from the operation site is a serious complication and can occur
in 0.5% to 3.9% of patients.5, 21
Most bleeding occurs in the first 24 hours and half of patients require reexploration.5 Furthermore, severe bleeding may further compromise
the edematous airway. Postoperative bleeding may be influenced by the physician
performing the surgical procedure as well as by the fact that the donor site
was left open.5 In our study, there were 2
patients (2%) with bleeding, 1 of whom had partial factor VII deficiency and
mild thrombocytopenia. Bleeding ceased after infusion of fresh frozen plasma
and tranexamic acid. The second patient had profuse bleeding from the donor
site that required surgical revision. Neither of the patients required a blood
transfusion.
Our study may be criticized because the providing anesthesiologists
were aware of the anesthetic drugs being administered. However, recovery end
points and complication rates were evaluated in a blinded fashion. A second
criticism of this study is that the oxygen saturation (as measured by pulse
oximetry) values were not recorded postoperatively, although all the patients
were monitored with pulse oximeter for the first 24 hours after their operation.
In conclusion, when compared with isoflurane administration for the
maintenance of general anesthesia, propofol-based anesthesia was associated
with more rapid mental and psychomotor recovery. However, the incidence of
airway-related complications as well as home readiness was similar between
the groups. Thus, the incidence of early postoperative complications after
pharyngeal flap surgery is not influenced by isoflurane anesthesia or propofol-based
intravenous anesthesia.
AUTHOR INFORMATION
Accepted for publication September 10, 2001.
Corresponding author: Brian Fredman, MB, BCh, Department of Anesthesiology
and Critical Care Medicine, Meir Hospital, 44281, Kfar Saba, Israel.
From the Departments of Anesthesiology and Critical Care Medicine (Drs
Bennun, Goldstein, Zohar, Jedeikin, and Fredman) and Otolaryngology, Head
and Neck Surgery (Dr Finkelstein), Meir Hospital, Sapir Medical Center, Kfar
Saba, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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