+++
Physiologic Effects on the Cardiovascular System
++
Thoracic epidural anesthesia (TEA) blocks the cardiac afferent and
efferent sympathetic fibers with loss of chronotropic and inotropic drive to
the myocardium.1 The level of sympathetic blockade that
follows a TEA depends in part on the degree of sympathetic tone before the
block. This may explain why different studies report different effects of
TEA on the cardiovascular system. Goertz et al.2 used
transesophageal echocardiography to assess the effects of TEA on cardiac
function in healthy volunteers. TEA was not shown to produce significant
changes in systolic or diastolic arterial pressures, heart rate, left
ventricular end-systolic and end-diastolic cross-sectional areas and left
ventricular wall stress as measured under general anesthesia. However, left
ventricular maximum elastance, as a measure of left ventricular
contractility, was significantly reduced. This observation led the
investigators to conclude that TEA severely alters left ventricular
contractility even in healthy subjects without preexisting cardiac disease.
In another study of healthy subjects, left ventricular ejection and
diastolic filling performance were unchanged, but a decrease in cardiac
output and fractional area shortening were observed3
(Table 57–1).
++
++
Ottesen4 reported that TEA does not affect oxygen
consumption (Vo2) during
exercise. However, even at moderate workloads, systemic arterial blood
pressures were significantly lower with TEA than during control exercise in
healthy subjects. No other changes in systemic or pulmonary circulatory
parameters were observed. In another exercise study, Wattwil et al.5 reported that after administration of TEA, heart
rate, systolic blood pressure, stroke volume, and cardiac output decreased.
They also injected local anesthetic (0.5% bupivacaine) intramuscularly
and observed similar cardiovascular effects, leading them to the conclusion
that the changes may be due in part to systemic effects.
++
Several studies have documented the effects of TEA on cardiovascular
function in patients with heart disease. In a small study of 10 patients
scheduled for thoracotomy, a TEA with a mean analgesic level of C7 to T5 had
only minor effects on the cardiovascular system.6 In
patients with severe coronary artery disease and unstable angina pectoris,
Blomberg et al.7 observed that TEA relieved chest pain. It
also significantly decreased heart rate, systolic arterial, and pulmonary
arterial and pulmonary capillary wedge pressures without any significant
changes in coronary perfusion pressure, cardiac output, stroke volume, and
systemic or pulmonary vascular resistances.
++
Intraoperatively, Reinhart et al.8 observed lower cardiac
index and oxygen delivery (Qo2)
in patients receiving TEA and general anesthesia than in those receiving
general anesthesia alone; Vo2
were similar. They also reported that the oxygen supply-demand ratio
(Qo2/Vo2)
was less in the TEA group throughout the perioperative period and about
30% below baseline values during early recovery. The authors attributed
the reduced adaptation of cardiac output to tissue oxygen needs during TEA
to negative inotropic and chronotropic effects of sympathetic blockade. In
patients on chronic β-adrenergic blocking medication, TEA has been
reported to induce a moderate decrease in mean arterial pressure and
coronary perfusion pressure, but without producing clinically significant
cardiovascular effects.9
++
Berendes et al.10 reported that in patients undergoing
coronary artery bypass grafting (CABG) with combined TEA and general
anesthesia, regional left ventricular function was significantly improved,
and cardiac troponin I concentrations were reduced when compared with
patients receiving general anesthesia alone (Figure 57–1). In
addition, TEA reduced the concentrations of atrial and brain natriuretic
peptides. The authors concluded that cardiac sympathectomy by TEA improves
regional left ventricular function and reduces postoperative ischemia after
CABG. In another study of CABG patients, TEA was associated with better
hemodynamic stability before and after cardiopulmonary bypass when compared
with general anesthesia.11 In addition, TEA may provide
improvement in pulmonary function, possibly because of more profound
postoperative analgesia after cardiac surgery.12
++
++
Cardiac function was also evaluated in patients with two- or three-vessel
coronary artery disease who were treated with β-adrenergic blocking
agents. Systolic and diastolic arterial pressures, heart rate, and global
and regional ejection fractions using equilibrium radionuclide angiography
were measured at rest and during maximal exercise before and after TEA.
During TEA exercise, systolic arterial pressure, diastolic arterial
pressure, and the rate–pressure product, but not heart rate, were
significantly lower when compared with control exercise. The global and
anterolateral ejection fractions were significantly higher, and the regional
wall motion score was significantly lower during TEA exercise than during
control exercise. ST-segment depression was significantly lower during TEA
exercise.13 Schmidt et al.14 noted that
in patients with coronary artery disease, TEA induced a significant
improvement in left ventricular diastolic function, whereas indices of
systolic function did not change (Figures 57-2, 57-3, and 57-4).
++
++
++
++
Patients with cardiac disease are prone to hemodynamic changes during
laryngoscopy and intubation, thus placing them at risk for ischemic events.
TEA has been associated with stable hemodynamics and preservation of
baroreflex sensitivity, suggesting withdrawal of vagal activity. Licker et al.15 reported that patients who received TEA in addition
to general anesthesia had smaller increases in mean arterial pressure and
heart rate during laryngoscopy and tracheal intubation than those who
received general anesthesia only; this would suggest that TEA affords
hemodynamic protection during these maneuvers.
++
+++
Management of Cardiac Disease
++
TEA has been used in the management of cardiac disease (Figure 57–5). Cardiac sympathetic blockade by TEA dilates stenotic coronary
arteries and has been used to control pain in patients with unstable
angina.16 The mechanism by which TEA reduces angina during
long-term treatment is unclear. It has been reported that the improvement in
symptoms probably results partly from an anesthetic effect and does not
appear to be related to a change in myocardial blood flow or a reduction in
stress-induced ischemia. In addition, new myocardial infarctions are not
masked or missed in patients receiving TEA for symptomatic treatment of
angina.17 The effects of long-term, home self-treatment
with TEA on angina, quality of life, and safety were studied by Richter et al.18 Thirty-seven patients with refractory angina began
treatment with TEA, using a subcutaneously tunneled epidural catheter and a
bupivacaine solution. All but one of the patients improved symptomatically.
The improvement was maintained throughout the treatment period (4 days to 3
years). The authors reported that the frequency of anginal attacks and
nitroglycerin intake decreased, whereas the overall self-rated quality of
life assessed by visual analog scale (VAS) increased.
++
++
Studies have looked at the number of anginal attacks and the severity of
myocardial ischemia assessed by 48-hour ambulatory Holter monitoring in
patients with severe, refractory unstable angina receiving TEA or standard
antianginal therapy. Olausson et al.19 reported that the
incidence of myocardial ischemia was lower in the TEA group (22% versus
61%; P < .05). The number of ischemic episodes per patient was
1.0 ± 0.6 in the TEA group and 3.6 ± 0.9 in the control
group (P < .05), and the episode duration per patient was
4.1 ± 2.5 minutes and 19.7 ± 6.2 minutes in the TEA and the
control groups, respectively (P<.05).
+++
Coronary Artery Bypass Grafting
++
As an anesthetic for CABG, TEA offers thoracic and cardiac
sympathectomy, attenuation of the stress response, analgesia for surgery,
and postoperative analgesia, which may improve outcome after CABG. One
review suggests that for patients undergoing CABG surgery, the risk:benefit
ratio is in favor of epidural and spinal anesthesia, provided no specific
contraindications exist and the guidelines for the use of regional
techniques in cardiac surgery are followed.20 Patients
managed with regional anesthetic techniques seem to benefit from superior
postoperative analgesia, shorter postoperative ventilation, reduced
incidence of supraventricular arrhythmias, and lower rates of perioperative
myocardial infarction. The results of this particular analysis suggest that
for each episode of neurologic complication that might occur, 20 myocardial
infarctions and 76 episodes of atrial fibrillation would be prevented. Thus,
regional anesthesia and analgesia would be considered an effective strategy
that improves perioperative morbidity.
++
As an adjunct to general anesthesia, TEA can be useful in off-pump CABG.
Salvi et al.21 reported on 106 patients receiving TEA
combined with sevoflurane general anesthesia. The mean time to extubation
was 4.6 ± 2.9 hours. VAS scores for pain during the first 24-hour
period were less than 2 in all patients. The average intensive care unit
(ICU) stay was 1.5 ± 0.8 days. Incidences of perioperative
myocardial infarction, myocardial ischemia, and atrial fibrillation were
2.8%, 7.5%, and 10.6%, respectively. Two patients died—one from
multiorgan failure and the other from myocardial infarction. Heart rate,
mean arterial pressure, cardiac index, and systemic vascular resistance were
not affected by TEA alone. Mean arterial pressure and cardiac index
decreased (P < .05) when general anesthesia was induced and remained
stable thereafter. Neither heart rate nor systemic vascular resistance
changed from baseline during the operation. The authors concluded that
thoracic epidural block as an adjunct to general anesthesia is a feasible
technique in off-pump CABG. It induces intense postoperative analgesia and
does not compromise central hemodynamics.
++
Kessler et al.22 compared TEA alone (ropivacaine plus
sufentanil, n = 30), TEA combined with general anesthesia (n = 30), and
general anesthesia alone in patients scheduled for off-pump CABG surgery.
The general anesthetic consisted of propofol, remifentanil, and
cisatracurium. Intraoperative heart rate decreased significantly with TEA
alone or in combination with general anesthesia. None of the patients with
TEA alone was admitted to the ICU; all were monitored in the intermediate
care unit for an average of 6 hours postoperatively and were allowed to eat
and drink as desired on admission. Postoperative pain scores were lower in
both groups with TEA. There were no differences among groups in overall
patient satisfaction. The authors concluded that general anesthesia + TEA
appeared to be the most comprehensive anesthetic, allowing for
revascularization of any coronary artery and providing good hemodynamic
stability and reliable postoperative pain relief.
++
Stritesky et al.23 reported on 129 patients undergoing
cardiac surgery awake with spontaneous ventilation using TEA for anesthesia.
Ninety patients underwent on-pump surgery and 39 underwent off-pump surgery.
A thoracic epidural block was placed 1 hour before skin incision at the
T2-T4 level. Forty-two cases had aortic valve replacement, 32 patients
underwent on-pump CABG, 12 had off-pump CABG, 12 had mitral valve
replacement, 27 underwent sternal wound reexploration, and 4 had combined
procedures. There were 10 conversions to general anesthesia and no deaths.
Mean duration of stay in the ICU was 7.2 hours; in-hospital stay 5.1 days.
Low cardiac output syndrome, stroke, renal insufficiency, and pulmonary
dysfunction were not observed in patients who underwent TEA. Less
postoperative pain was also demonstrated.
++
The authors felt that TEA provided rapid recovery and early outpatient care
of patients after cardiac surgery and that TEA would be beneficial for
patients with preoperative pulmonary dysfunction.
++
Several other studies have shown TEA to be effective for CABG surgery in the
awake patient24–26 (Figure 57–6). Kessler et al.27 reported on the feasibility and complications of TEA
as the sole anesthetic in 20 patients undergoing beating-heart arterial
revascularization. Minimally invasive direct coronary CABG (MIDCAB) via
partial lower sternotomy was used in 10 patients with single-vessel disease,
whereas complete median sternotomy with off-pump coronary artery bypass
grafting (OPCAB) was chosen for 10 patients with multivessel disease. An
epidural catheter was inserted at the T1-2 or T2-3 level. An epidural
infusion of ropivacaine 0.5% and sufentanil 1.66 mcg/mL was started to
establish anesthetic levels at C5-6 for OPCAB and at T1-2 for MIDCAB. Nine
OPCAB and eight MIDCAB procedures were completed while the patients were
awake and spontaneously breathing during the entire procedure. Three
patients required intraoperative conversion to GA because of surgical
pneumothorax (OPCAB), insufficient anesthesia, or phrenic nerve palsy (both
MIDCAB).
++
++
In both groups, the heart rate decreased significantly
(P < .05) by 10–15% during the procedure. Compared with
baseline, mean arterial blood pressure was decreased significantly only
during coronary anastomosis. Paco2 increased from 42
± 2 mm Hg to 46 ± 7 mm Hg (P < .05) throughout
the perioperative course during OPCAB, whereas it remained almost unaltered
during MIDCAB procedures. All patients rated TEA as “good” or “excellent”
and reported a high degree of satisfaction with the procedure.
++
Anderson et al.28 found similar results when studying the
use of TEA for awake cardiac surgery. He reported on a total of 10
operations including 7 MIDCAB, 2 transmyocardial revascularizations (TMR)
and 1 MIDCAB/TMR hybrid. The mean preoperative forced expiratory volume for
1 second (FEV1) was 1.9 liters. Significant intraoperative
hypoxia or hypercarbia was not seen. One patient required intubation during
the procedure for restlessness not associated with hypoxia. Two others
required brief periods of assisted ventilation. All procedures were
completed without incident. The mean operating time and length of stay were
70 minutes and 4.7 days, respectively. Postoperative pain control and
patient satisfaction were excellent.
++
Although ischemic damage to the myocardium is inevitable during CABG
surgery, the extent of the damage may be influenced by the anesthetic
technique used. Barrington et al.29 reported on the effect
of TEA on the release of troponin I, time to tracheal extubation, and
analgesia during elective CABG surgery. One hundred twenty patients were
randomized to general anesthesia or general anesthesia plus TEA. The general
anesthesia group received fentanyl (7–15 mcg/kg) and a morphine infusion.
The TEA group received fentanyl (5–7 mcg/kg) and an epidural infusion of
ropivacaine 0.2% and fentanyl 2 mcg/mL until postoperative day 3.
Researchers found no differences in troponin I levels between the study
groups. The time to tracheal extubation in the TEA group was 15 minutes
(range 10–20) compared with 430 minutes (range 284–590) in the general
anesthesia group (P < .0001). Analgesia was improved in the TEA
group compared with the general anesthesia group. Mean arterial blood
pressure and systemic vascular resistance in the ICU were lower in the TEA
group. They concluded that TEA for CABG had no effect on troponin release
but improved postoperative analgesia and was associated with a reduced time
to extubation (Table 57–2; Figure 57–7). Kendall et al.30 conducted a prospective, randomized study to
determine the baseline values of troponin T release after off-pump CABG in
30 patients randomly allocated to receive propofol, isoflurane, or
isoflurane plus TEA. All other treatments were standardized. They found that
mean troponin T levels at 24 hours were not significantly different between
the groups (P = .41).
++
++
++
Loick et al.31 investigated the effects of general
anesthesia with TEA or with intravenous clonidine on the stress response and
incidence of myocardial ischemia in patients undergoing CABG surgery.
Seventy patients scheduled for elective CABG surgery received general
anesthesia with sufentanil and propofol. In 25 patients, TEA was induced
before general anesthesia and continued during the entire study period.
Another 24 patients received intravenous clonidine as a bolus of 4 mcg/kg
before the induction of general anesthesia. Clonidine was then infused at a
rate of 1 mcg/kg/h during surgery and at 0.2–0.5 mcg/kg/h postoperatively.
The control group consisted of 21 patients who underwent general anesthesia
as performed routinely. Hemodynamics, plasma epinephrine and norepinephrine,
cortisol, troponin T, and other cardiac enzymes were measured pre- and
postoperatively. Both TEA and clonidine reduced the postoperative heart rate
compared with the control group without jeopardizing cardiac output or
perfusion pressure. Plasma epinephrine increased perioperatively in all
groups but was significantly lower in the TEA group. Neither TEA nor
clonidine affected the increase in plasma cortisol. The release of troponin
T was attenuated by TEA. New ST-segment elevation or depression occurred in
more than 70% of the control patients but only in 40% of the clonidine
group and in 50% of the TEA group. The investigators concluded that TEA,
but not intravenous clonidine, combined with general anesthesia for CABG
demonstrated a beneficial effect on the perioperative stress response and
decreased postoperative myocardial ischemia.
++
Liu et al.32 recently conducted a meta-analysis of 15 trials that studied the effects of perioperative central neuraxial analgesia
on outcome after CABG. The total number of patients was 1178. According to
the analysis, TEA does not affect the incidences of mortality (0.7% TEA
vs 0.3% general anesthesia) or myocardial infarction (2.3% TEA vs
3.4% general anesthesia). However, TEA does significantly reduce the risk
of arrhythmias (odds ratio 0.52), pulmonary complications (odds ratio 0.41),
and time to tracheal extubation (by 4.5 hours). TEA reduces analog pain
scores at rest by 7.8 mm and with activity by 11.6 mm. The authors concluded
that there were no differences in the rates of mortality or myocardial
infarction after CABG surgery with central neuraxial analgesia. More rapid
tracheal extubation, decreased pulmonary complications and cardiac
arrhythmias, and reduced pain scores were, however, benefits of TEA.
++
Fillinger et al.33 conducted a prospective, randomized,
nonblinded clinical trial assessing the effects of anesthetic on recovery
from cardiac surgery. Sixty patients scheduled for elective cardiac surgery
with cardiopulmonary bypass were randomly assigned to 1 of 2 study groups.
One group was to receive general anesthesia during surgery and intravenous
opioid analgesia after surgery, whereas the second group received TEA
combined with general anesthesia during surgery and epidural analgesia for
the first 24 postoperative hours. They found no statistically significant
differences in time to tracheal extubation, duration of postoperative ICU
stay, duration of postoperative hospitalization, pain control, urinary free
cortisol, cardiopulmonary complication rate, or total hospital charges.
++
The most feared complication of TEA is epidural hematoma. Studies have found
that, in the setting of cardiac surgery, following a set of standard safety
measures averts the occurrence of symptomatic epidural hematomas. These
measures consist of preoperative coagulation tests including aPTT, platelet
count, and prothrombin time and the cessation of antiplatelet drugs before
surgery.34,35 Scott et al.36 conducted a
prospective, randomized, controlled study of the incidence of major organ
complications in 420 patients undergoing routine CABG with or without TEA.
All patients received a standardized general anesthetic. Patients in the TEA
group received TEA for 96 hours. Patients in the general anesthesia group
received narcotic analgesia for 72 hours. Both groups received supplementary
oral analgesia. New supraventricular arrhythmias occurred in 21 of 206
patients (10.2%) in the TEA group compared with 45 of 202 patients
(22.3%) in the general anesthesia group (P = .0012). Pulmonary function
(maximal inspiratory lung volume) was better in the TEA group
(P < .0001). Extubation was achieved earlier
(P < .0001) and with significantly fewer lower respiratory tract
infections in the TEA group (TEA = 31 of 206, general anesthesia = 59 of
202; P = .0007). Significantly fewer patients had acute confusion (general
anesthesia = 11 of 202, TEA = 3 of 206; P = .031) and acute renal failure
(general anesthesia = 14 of 202, TEA = 4 of 206; P = .016) in the TEA group.
The incidence of stroke was insignificantly less in the TEA group (general
anesthesia = 6 of 202, TEA = 2 of 206; P = .17). No neurologic complications
were associated with TEA. The researchers concluded that continuous TEA
significantly improved the quality of recovery after CABG surgery compared
with general anesthesia and conventional narcotic analgesia.
++
Turfrey et al.37 reported similar results after performing
a retrospective analysis of the perioperative course of 218 patients who
underwent routine CABG. All patients received a standardized general
anesthesia, using target-controlled infusions of alfentanil and propofol.
One hundred patients also received TEA with bupivacaine and clonidine,
started before surgery and continued for 5 days after surgery. The remaining
118 patients received a target-controlled infusion of alfentanil for
analgesia for the first 24 hours after surgery, followed by intravenous
patient-controlled morphine analgesia for a further 48 hours. New
arrhythmias requiring treatment occurred in 18% of the TEA group of
patients compared with 32% of the general anesthesia group
(P = .02). There was also a trend toward a reduced incidence of respiratory
complications in the TEA group. The time to tracheal extubation was
decreased in the TEA group, with 21% of the patients being extubated
immediately after surgery compared with 2% in the general anesthesia
group (P < .001). No serious neurologic problems resulted from the
use of TEA.
++
Although most studies on the use of TEA in cardiac surgery have focused
on CABG, a few investigations and case reports describe its use in valvular
surgery. Hemmerling et al.38 have reported on the
feasibility and hemodynamic stability of immediate extubation after simple
or combined aortic valve surgery using TEA and general anesthesia. Thirty
patients with an ejection fraction of more than 30% undergoing aortic valve
surgery were studied prospectively. After initiation of TEA, general
anesthesia was induced with fentanyl 2–4 mcg/kg, propofol 1–2 mg/kg, and
endotracheal intubation was facilitated by rocuronium. Anesthesia was
maintained with sevoflurane titrated according to bispectral index (target =
50). Perioperative analgesia was provided by TEA (bupivacaine 0.125% at
6–14 mL/h). Patients underwent simple aortic valve surgery (n = 17) or
combined aortic valve surgery (n = 13) with additional CABG (n = 8),
replacement of the ascending aorta (Bentall procedure; n = 4), and repair of
open foramen ovale (n = 1). All 30 patients were extubated within 15 minutes
after surgery at 36.5°C. There was no need for reintubation.
Pain scores were low immediately after surgery and at 6, 24, and 48 hours
after surgery. During and up to 6 hours after surgery, there was no
significant hemodynamic change due to TEA. Fifteen of the 30 patients needed
temporary pacemaker activation. There were no complications related to TEA.
The authors concluded that immediate extubation is feasible after aortic
valve surgery with TEA and maintenance of hemodynamic stability throughout
surgery.
++
Klokocovnik et al.39 describe a patient who underwent
aortic valve replacement through a ministernotomy while awake under TEA. The
procedure was not converted to general anesthesia or to a conventional
operation and was performed without adverse incidents. The patient was
discharged from the hospital on the second postoperative day. There were no
complications within 30 days after surgery. Kozian et al.40 report on a tricuspid valve replacement without any
adverse events using TEA and balanced general anesthesia.
++
The effects of combined TEA and general anesthesia on hemodynamic and
respiratory variables have been reported in children undergoing cardiac
heart surgery. Slin'ko et al.41 report that in 55 patients
age 1–14 years, TEA was used in combination with oxygen-air-halothane
anesthesia. In one group, lidocaine and fentanyl were used for TEA, and in
another clonidine and lidocaine. In a control group, standard intravenous
fentanyl-diazepam anesthesia was combined with oxygen-air-halothane
anesthesia. In the clonidine-lidocaine group, the endocrine stress response
was decreased in comparison with other groups, even without narcotics.
Hemodynamics remained stable even in patients with NYHA (New York Heart
Association) class III–IV heart disease. These same investigators also
report that TEA has been found to be safe and effective for postoperative
pain in children after heart surgery.42 In one study, 40
children received epidural analgesia after open-heart surgery. Lidocaine was
injected in a dose of 1.5–2 mg/kg every 1.5–2 hours. Controls (n = 16)
received intravenous fentanyl + diazepam analgesia. Respiratory response and
awakening were significantly earlier (P < .001) in the epidural
group. Cooperation with nurses was much better in this group, too. No side
effects were observed in the epidural group.
++
Peterson et al.43 report on a retrospective study
describing the results of the use of regional anesthesia in 220 pediatric
cardiac operations. They indicate that tracheal extubation in the operating
room could be achieved for 89% of the patients. Ninety-five percent of
the patients had pain scores less than or equal to 4.0 at all intervals
postoperatively. Adverse effects of regional anesthesia included emesis,
pruritus, urinary retention, postoperative transient paresthesia, and
respiratory depression (Table 57–3). The incidence of peridural
hematoma was zero. The rate of adverse effects was lower using the TEA
approach compared with various caudal, lumbar epidural, and spinal
approaches. Hospital stay was not prolonged because of regional anesthetic
complications. In this study, regional anesthesia was found to be safe and
effective in the management of pediatric patients undergoing cardiac
surgery.
++
++
Hammer et al.44 evaluated whether spinal anesthesia or TEA
in combination with general anesthesia was associated with circulatory
stability, satisfactory postoperative sedation/analgesia, and a low
incidence of adverse effects. They found no significant differences in the
incidence of clinically significant changes in vital signs, oxygen
desaturation, hypercarbia, or vomiting when comparing TEA with spinal
anesthesia for children undergoing cardiac surgery.
+++
Noncardiac Surgery in Patients with Cardiovascular Disease
++
When TEA is used for major vascuar surgery, it is reported to provide
more hemodynamic stability and better pain control than general anesthesia
or monitored anesthesia care with local anesthesia.45 TEA
has been found safe and effective for endovascular aortic aneurysm repair,
especially in patients with severe coexisting diseases. In addition, TEA
minimizes sedation and postoperative analgesic requirements, decreases
cardiopulmonary complications, and decreases overall hospital stay, thereby
reducing cost.
++
Bonnet et al.46 investigated the hemodynamic
consequences of abdominal aortic surgery with infrarenal cross-clamping in
21 patients randomized to one of two groups. In group I (n = 11),
neuroleptanesthesia was used, whereas group II (n = 10) received TEA at the
T8-T9 level. In all patients, hemodynamic measurements were performed using
pulmonary artery catheters. The use of TEA was characterized by greater
hemodynamic stability during surgery. Patients in the neuroleptanesthesia
group experienced significant lability of blood pressure, heart rate, and
cardiac index.
++
Her et al.47 compared intraoperative hemodynamic variables
and postoperative morbidity between a group of patients undergoing abdominal
aortic surgery—one with combined TEA and general anesthesia (n = 30) and
one with general anesthesia alone (n = 19). Patients in the combined group
were given epidural bupivacaine intraoperatively and epidural morphine
postoperatively. After cross-clamping of the aorta, cardiac index and
pulmonary capillary wedge pressure did not change in the combined group,
whereas cardiac index decreased (mean change, 0.30
L/min/m2; P = .006) and pulmonary capillary wedge pressure
increased (mean change 1 mm Hg; P = .007) in the group with general
anesthesia alone. After unclamping of the aorta, cardiac index increased in
both groups (mean change, 0.26 L/min/m2,
P = .002 and 0.30 L/min/m2 P = .001, respectively).
Postoperatively, the necessity for ventilatory support and the incidence of
respiratory failure were lower in the combined group than in the general
anesthesia alone group (P =.0002 and P= .018, respectively). In addition,
vasodilator therapy was required less frequently in the combined group
(P = .002). Duration of ICU stay was shorter in the combined group (2.7 days
vs 3.8 days; P = .003). The authors concluded that for infrarenal abdominal
aortic surgery, combined TEA and general anesthesia is associated with more
stable intraoperative hemodynamics and significantly less postoperative
morbidity than general anesthesia alone.
++
Different results, however, were obtained by Garnett et al.,48 who studied the incidence of perioperative
myocardial ischemia in patients undergoing elective aortic surgery. Patients
were randomly assigned to one of two groups. One group (n = 48) received
combined general anesthesia and epidural anesthesia and postoperative
epidural analgesia for 48 hours; the other group (n = 51) received general
anesthesia followed by postoperative intravenous analgesia. The authors
reported that myocardial ischemia was common because it occurred in 55%
of patients. In the hospital, preoperative ischemia was uncommon (combined =
8; general anesthesia = 3). Ischemic events were common intraoperatively
(combined = 25; general anesthesia = 18), with mesenteric traction producing
the largest number of events (combined = 11; general anesthesia = 11).
Postoperative ischemia was most common on the day of surgery. Termination of
epidural analgesia produced rebound ischemia (60 events in 9 patients). The
authors concluded that combined general anesthesia and epidural anesthesia
and postoperative epidural analgesia do not reduce the incidence of
myocardial ischemia or morbidity compared with general anesthesia and
postoperative intravenous analgesia.
++
Norris et al.49 studied patient outcomes in 168 patients
undergoing surgery of the abdominal aorta using different types of
anesthesia. Patients were randomly assigned to receive either TEA combined
with general anesthesia or general anesthesia alone intraoperatively and
either intravenous or epidural patient-controlled analgesia (PCA)
postoperatively (four treatment groups). PCA was continued for at least
72 hours. Length of stay and direct medical costs for patients surviving to
discharge were similar among the four treatment groups. Postoperative
outcomes were also similar among the groups with respect to death,
myocardial infarction, myocardial ischemia, reoperation, pneumonia, and
renal failure. Postoperative pain scores were the same for the four groups,
but epidural PCA was associated with a significantly shorter time to
extubation (P = .002). Times to ICU discharge, ward admission, first bowel
sounds, first flatus, tolerating clear liquids, tolerating regular diet, and
independent ambulation were also equivalent for the four groups. The authors
concluded that in patients undergoing surgery of the abdominal aorta, TEA
combined with general anesthesia and followed by either intravenous or
epidural PCA, offers no major advantage or disadvantage when compared with
general anesthesia alone followed by either intravenous or epidural PCA.
++
Davies et al.50 prospectively studied intraoperative
hemodynamics and outcomes in 50 patients undergoing elective abdominal
aortic surgery who were randomized to receive either combined epidural
(T9-T10 level) and general anesthesia and postoperative epidural analgesia
or general anesthesia and postoperative intravenous morphine infusion. The
use of intraoperative vasopressors was significantly higher in the combined
group (P < .01), but the use of intravenous glyceryl trinitrate was
significantly lower (P < .01). No significant difference was found
between groups in regard to blood loss, volume replacement, and the number
of patients requiring postoperative ventilation. Two patients in the
combined group died postoperatively compared with one in the general
anesthesia group (nonsignificant). There was no significant difference
between groups in the total number or type of postoperative complications.
The authors concluded that combined epidural anesthesia with general
anesthesia altered intraoperative cardiovascular management but did not
affect postoperative outcome.
++
Gelman et al.51 studied the effect of TEA on the
cardiovascular function of morbidly obese patients undergoing gastric bypass
surgery. Patients were given general anesthesia alone or a combination of
TEA and general anesthesia. Circulatory function was measured and calculated
using radial artery cannulation and pulmonary artery catheterization with
pulmonary artery thermodilution catheters. During surgery, the TEA group
demonstrated greater decreases in cardiac index, left and right ventricular
stroke work, systolic blood pressure–heart rate product, arteriovenous
oxygen content difference, oxygen consumption, and intrapulmonary shunt
compared with the general anesthesia group. Postoperatively, epidural
analgesia was associated with decreases in left ventricular stroke work,
systolic pressure–heart rate product, arteriovenous oxygen content
differences, and oxygen consumption compared with values observed when
patients experienced pain. Morphine given for relief of postoperative pain
was not associated with significant changes in cardiovascular function. The
authors concluded that continuous TEA used for upper abdominal surgery in
morbidly obese patients benefits intraoperative cardiovascular function, as
reflected by a decrease in left ventricular stroke work, and postoperatively
by relief of pain.
+++
Acute Pain Management
++
In patients with cardiac disease undergoing cardiac surgery, good pain
management is an important goal to improve outcomes and reduce postoperative
complications. The value of TEA in this setting has been studied
extensively. Royse et al.52 studied 80 patients who were
randomized to TEA or intravenous morphine analgesia for postoperative pain
control after CABG with cardiopulmonary bypass. A thoracic epidural catheter
was inserted the night before surgery at either the T1-T2 or T2-T3 level.
Eight milliliters of 0.5% ropivacaine with 20 mcg fentanyl was
administered before induction of anesthesia. Ropivacaine 0.2% with 2
mcg/mL fentanyl was then infused at a rate of 5–14 mL/h to attain a sensory block of
T1 to T10. Pain was measured using a VAS scale from 0 to 10. Psychological
morbidity, intraoperative hemodynamics, ventricular function, lung function,
and physiotherapy cooperation were also assessed. On the third postoperative
day, TEA and morphine were stopped, and only oral medications were used.
Acetaminophen, indomethacin, and tramadol were allowed as supplemental
analgesics in both groups. Pain scores were significantly less with TEA on
postoperative days 1 and 2 at rest and with coughing. When TEA and morphine
were stopped on day 3, there were no significant differences. Secondary
endpoints of postoperative depression and posttraumatic stress subscales of
the Minnesota Multiphasic Personality Inventory were lower with TEA. In
addition, extubation occurred earlier with TEA (2.6 vs 5.4 hours;
P < .001). TEA showed improved physiotherapy cooperation
(P < .001), arterial oxygen tension (P = .041), and peak expiratory
flow rate (P = .001). Mean arterial pressure was lower with TEA
(P = .036); otherwise, no differences were found in intraoperative
hemodynamics or ventricular function.
++
Liem et al.53 studied the effects of intraoperative
and postoperative epidural pain management during and after CABG on the
recovery time, postoperative pulmonary and cardiac parameters, VAS scores,
and sedation scores. They compared the findings with those of patients
anesthetized with general anesthesia whose postoperative pain was relieved
with intermittent intravenous administration of nicomorphine. Fifty-four
patients were studied postoperatively after uncomplicated CABG surgery. In
the TEA group (n = 27), intraoperative analgesia was based on TEA in
combination with general anesthesia. In the general anesthesia group (n =
27), intravenous anesthesia with high-dose sufentanil and midazolam was
used. Postoperative pain management in the general anesthesia group
consisted of intermittent intravenous administration of nicomorphine 0.1
mg/kg every 6 hours, whereas in the TEA group patients received a continuous
high TEA with 0.125% bupivacaine plus sufentanil. Patients in the TEA
group awakened earlier (148 minutes vs 335 minutes), resumed spontaneous
respiration earlier (326 minutes vs 982 minutes), and were extubated earlier
(463 minutes vs 1140 minutes). VAS scores, sedation scores, and
postoperative Pao2 were
significantly (P ≤ .01) better in the TEA group. The incidence
of tachycardia (15 vs 2 patients) and postoperative myocardial ischemia (12
vs 4 patients) was higher in the general anesthesia group. The authors
concluded that intraoperative and postoperative pain treatment with
epidurally administered bupivacaine plus sufentanil improved the recovery
time, as well as pulmonary and cardiac outcomes after CABG, when compared
with intravenous postoperative pain treatment after intraoperative general
anesthesia with sufentanil and midazolam.
++
Hemmerling et al.54 studied 100 consecutive patients
undergoing OPCAB surgery to examine the feasibility of immediate extubation
after using opioid-based analgesia or TEA and compare postoperative
analgesia between continuous TEA versus PCA. Perioperative analgesia was
provided by TEA (n = 63) using bupivacaine 0.125% at a continuous rate of
8–14 mL/h and repetitive boluses of bupivacaine 0.25% during surgery. In
the other group (n = 37), perioperative analgesia was achieved by
intravenous fentanyl boluses (up to 15 mcg/kg) and remifentanil 0.1–0.2
mcg/kg/min, followed by morphine PCA after surgery. Ninety-five patients
were extubated within 25 minutes after surgery (TEA n = 62; PCA n = 33).
Five patients were not extubated immediately because their core temperature
was lower than 35°C. One patient was reintubated because of
agitation (TEA group); one was reintubated because of severe pain and
morphine-induced respiratory depression (PCA group). Pain scores were
generally low after surgery, with pain scores in the TEA group being
significantly lower immediately, at 6 hours, 24 hours, and 48 hours after
surgery (P < .05) (Figure 57–8). The authors concluded
that immediate extubation is possible after OPCAB surgery using either
opioid-based analgesia or TEA, but TEA provides significantly lower pain
scores after surgery compared with morphine PCA.
++
++
However, when Bois et al.55 studied 124 patients to assess
the role of postoperative analgesia on myocardial ischemia after aortic
surgery using intravenous PCA or TEA, different results were obtained. In
the PCA group, a bolus of morphine, 0.05 mg/kg, was given, followed by 0.02
mg/kg of morphine on demand every 10 minutes. Bupivacaine 0.125% and
fentanyl 10 mcg/mL were used in the TEA group. Analgesics were titrated to
maintain a VAS score ≤ 3. The overall incidence of myocardial
ischemia was 18.4–18.2% for TEA and 18.6% for PCA
(P = not significant). There were no differences between the groups in the
total duration of ischemia per patient (22.2 ± 119.8 minutes for
TEA and 20.5 ± 99 minutes for PCA) and the number of episodes per
patient (0.69 ± 2.1 for TEA and 1.2 ± 4.9 for PCA).
Twenty-three patients had an adverse cardiac outcome, but there were no
differences between the groups. Although the postoperative pain control was
superior with TEA, its use did not result in a lower incidence of early
myocardial ischemia when compared with intravenous PCA with morphine.
++
In patients who underwent CABG, a comparative audit of the use of TEA versus
intravenous opioids for postoperative pain control showed no significant
differences in the frequency or intensity of persistent pain (defined as
pain still present 2 or more months after surgery).56
Similarly in patients undergoing cardiac valve replacement, TEA was shown to
provide excellent analgesia in the peri- and postoperative period, but did
not offer a protective effect on chronic poststernotomy
pain.57