POSTOPERATIVE MANAGEMENT
Immediate postoperative care of the pediatric patient who has
undergone cardiothoracic surgery is an important period in the overall sequence of
anesthetic and surgical management. Although the primary influence on outcome is
determined by the conduct of the operation, postoperative care is an important factor.
As a member of the operative team, it is necessary that the anesthesiologist understand
and become involved during the immediate postoperative period. Detailed principles
of postoperative management of the pediatric cardiac surgical patients are beyond
the scope of this chapter. However, a few general guiding principles and approaches
are given to provide fundamental knowledge for the anesthesiologist.
The postoperative period can be characterized by a series of physiologic
and pharmacologic changes as the body convalesces from the abnormal biologic conditions
of CPB and cardiac surgery.[239]
During this period,
the effects of the cardiac operation, the patient's underlying disorders, the effects
of hypothermic CPB, and special techniques such as DHCA may create special problems.
In the immediate postoperative setting, abnormal convalescence and specialized problems
must be recognized and managed appropriately. Fortunately, most patients are able
to balance the cost imposed by the physiologic trespass created by the surgical repair
and the effects of CPB against the benefit of reduced pathophysiologic loading conditions,
resulting in low morbidity and mortality.
Therefore, the guiding principle in the management of the postoperative
patient is an understanding of both normal and abnormal convalescence after anesthesia
and cardiac surgery. The immediate postoperative period, even that of normal convalescence,
is one of continuous physiologic change because of the pharmacologic effects of residual
anesthetic agents and the ongoing physiologic changes secondary to abrupt alteration
in hemodynamic loading conditions, surgical trauma, and extracorporeal circulation.
Anesthesia and surgery affect not only the patient's conscious state but also cardiovascular,
respiratory, renal, and hepatic function; fluid and electrolyte balance; and immunologic
defense mechanisms. In spite of all these changes, postoperative care should be
predictable and standardized for most patients undergoing cardiac procedures.
In general, there are four temporal phases of postoperative management
in the cardiac patient: (1) transport to the ICU, (2) stabilization in the ICU,
(3) weaning from inotropic and ventilatory support, and (4) mobilization of fluids.
Patients proceed through these phases at variable rates based on such factors as
the underlying disease process, preoperative medical condition, sequelae of the surgical
procedure, duration of CPB, and presence or absence of intraoperative complications.
One of the most important functions of the ICU team is to identify postoperative
complications in the patient who convalesces abnormally and to provide interventional
therapy. Because physiologic change after cardiac surgery is dramatic but self-limiting
during normal convalescence, recognition of abnormal processes can be difficult.
Under such circumstances a uniform, multidisciplinary approach with experienced
clinicians and nurses facilitates the identification of any abnormalities in convalescence.
These abnormalities often are indications for closer observation, more invasive
monitoring, pharmacologic intervention, and increased cardiopulmonary technical support.
Complications include hypovolemia, residual structural heart defect, right and left
ventricular failure, hyperdynamic circulation, pulmonary artery hypertension, cardiac
tamponade, arrhythmias, cardiac arrest, pulmonary insufficiency, oliguria, seizures,
and brain dysfunction. It is critical to detect these departures from the normal
convalescent course and to treat them aggressively.
One important area in which the anesthesiologist can aid the recovery
of the cardiac patient is pain control. Pain and sedation are among the most common
problems requiring ICU intervention. Many factors influence the onset, incidence,
and severity of postoperative pain. The attenuation of the stress response in the
immediate postoperative period using infusions of potent opioids in the critically
ill infant reduces morbidity.[85]
Attenuation of
postoperative pain can be attempted with a preoperative
medication and an intraoperative anesthetic management technique that includes the
use of potent opioids. Patients who receive no opioids preoperatively or during
the operative procedure will require analgesics in the immediate postoperative period
once the inhalation anesthetic is eliminated. Most cases of postoperative pain can
be managed by the administration of small intravenous doses of opioids, usually morphine.
This is important in a patient being weaned from the ventilator during the early
postoperative period. Patients who are intubated and ventilated overnight should
receive adequate sedation and pain control until ventilatory weaning is begun. This
is usually accomplished by a continuous infusion of a benzodiazepine and an opioid.
Continuous infusion of sedatives and analgesics results in a more consistent and
reliable control of postoperative pain. When separated from mechanical ventilation,
the patient is concurrently weaned from the sedatives and analgesics. Under these
circumstances, careful titration of opioids often results in prompt pain relief.
In patients with reactive pulmonary artery hypertension, opioids have been shown
to prevent hypertensive crisis.[82]
Regional anesthesia may be used for postoperative pain control
in infants and children after thoracotomy. This method avoids opioid-induced respiratory
depression from intravenous doses of these drugs. The administration of opioids
in the epidural space is a very effective approach to pain management. This technique
is used in children for postoperative pain control when given in the epidural space
via the caudal route as a "single shot" or via a small caudal catheter. Morphine
or Dilaudid provides effective analgesia with a duration of 6 to 12 hours, with no
significant respiratory depression. Caudal morphine diluted in 0.05 to 0.075 mg/kg
delivered in a total volume of 1.25 mL/kg of sterile saline has been used with good
success in our practice. The use of regional anesthesia for postoperative pain appears
to be best suited for the child extubated in the early postoperative period. Relative
contraindications of this technique include hemodynamic instability and patients
with abnormal clotting profiles with continued active bleeding. Using this regional
technique, better arterial oxygenation, a more rapid ventilator wean, and decreased
postoperative respiratory complications may be expected. However, urinary
Figure 51-16
Demographic data for pediatric heart transplantation
by age. Stacked bar graph illustrates the total number and age distribution for
heart transplantation in patients less than 16 years of age. Note the rapid rise
in transplants performed during the late 1980s, with particular growth in the population
of children aged 5 years and under. Having peaked in the mid 1990s, the total number
of transplants (both adult and pediatric) has declined slightly, but the relative
age proportions within the pediatric population remain relatively constant. (Data
from the Registry of the International Society for Heart and Lung Transplantation.
[240]
)
retention occurs frequently in patients without a bladder catheter. Generally, no
treatment is required.
Children requiring large thoracotomies or a bilateral thoracosternotomy
incision (i.e., "clamshell") merit consideration for thoracic epidural analgesia.
This technique significantly reduces the respiratory depression and pulmonary mechanics
abnormalities that accompany the quantity of systemic opioids that would be necessary
to provide adequate analgesia for these excruciatingly painful incisions. If the
procedure requires systemic heparinization, we will typically defer placement of
these catheters until the heparin effect is neutralized. For the patient undergoing
coarctation repair via a left thoracotomy, we place the caudal or epidural catheter
after demonstration of motor function in the lower extremities. For patients undergoing
heart/lung transplantation, a thoracic epidural catheter is placed at a time in the
postoperative period when the patient can be weaned from intravenous medications
that will adversely impact on the patient's ability to breathe in close proximity
to the planned extubation. It is common for these patients to need a functioning
thoracic epidural for several days.
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