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Anesth Analg 2000;90:1020-1024
© 2000 International Anesthesia Research Society

PEDIATRIC ANESTHESIA

A Retrospective Examination of Regional Plus General Anesthesia in Children Undergoing Open Heart Surgery

Gregory B. Hammer, MD*,{dagger}, Khanh Ngo§, and Alex Macario, MD, MBA*,{ddagger}

Departments of *Anesthesia, {dagger}Pediatrics, and {ddagger}Health Research and Policy, Stanford University Medical Center, Stanford, California; and §University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania

Address correspondence and reprint requests to Gregory B. Hammer, MD, Department of Anesthesia, Rm H3580, Stanford University Medical Center, 300 Pasteur Dr., Stanford, CA 94305-5115. Address e-mail to ham{at}leland.stanford.edu


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 References
 
The use of regional anesthesia in combination with general anesthesia for children undergoing cardiac surgery is receiving increasing attention from clinicians. The addition of regional anesthesia may improve clinical outcomes and decrease costs as a result of the reduced need for postoperative mechanical ventilation. The goal of this retrospective chart review was to evaluate whether spinal anesthesia (SAB) or epidural anesthesia (EPID) in combination with general anesthesia was associated with circulatory stability, satisfactory postoperative sedation/analgesia, and a low incidence of adverse effects. The medical records of 50 consecutive children having open heart surgery with SAB or EPID and general anesthesia between September 1996 and December 1997 were reviewed. We found no significant differences in the incidence of clinically significant changes in vital signs, oxygen desaturation, hypercarbia, or vomiting. Patients in the SAB group received significantly more sedative/analgesic interventions than those in the EPID group.

Implications: Techniques for combining regional and general anesthesia in children undergoing open heart surgery are described. Patients having spinal anesthesia may require more sedative/analgesic interventions postoperatively compared with those having epidural anesthesia. A prospective study with a larger sample size is required to determine other differences, including the incidence of postoperative vomiting.


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 References
 
Adding regional anesthesia to general anesthesia for children undergoing cardiac surgery is receiving increasing attention from clinicians. Several studies have demonstrated benefits of regional anesthesia in adult and pediatric patients undergoing major surgery (1–9). Regional anesthesia may attenuate adverse physiologic stress responses associated with cardiothoracic surgery, including alterations in circulatory (tachycardia, hypertension, vasoconstriction), metabolic (increased catabolism), immunologic (impaired immune response), and hemostatic (platelet activation) systems (8,10,11). Regional anesthesia is also associated with improved morbidity and mortality in high-risk adult patients after noncardiac surgery (12,13). The use of regional anesthesia combined with light general anesthesia may facilitate early tracheal extubation after cardiac surgery in infants and children (9,14,15).

We use both spinal anesthesia (SAB) and epidural anesthesia (EPID) in combination with general anesthesia in pediatric patients for whom tracheal extubation is planned before leaving the operating room (OR) after open heart surgery. There is some debate as to which of these techniques is preferable. SAB is favored by some because it may be performed rapidly, whereas others favor EPID because it allows for repeated and/or continuous dosing during and after surgery.

The goal of this retrospective chart review was to compare SAB and EPID in combination with general anesthesia for children undergoing open heart surgery with respect to cardiovascular changes, postoperative sedation/analgesia, and the incidence of adverse effects.


   Methods
Top
 Abstract
 Introduction
 Methods
Results
 Discussion
 References
 
After institutional review board approval was obtained, we reviewed the medical records of 50 consecutive infants and children having open heart surgery with SAB or EPID and general anesthesia between September 1996 and December 1997. Nine of these patients were included in a recent review article (9). This time frame was chosen because one of the two anesthesiologists caring for children undergoing cardiac surgery at our institution during this period preferred SAB/general anesthesia, whereas the other opted for EPID/general anesthesia. Assignment of patients to these two anesthesiologists (and the two techniques) was random. Neither SAB nor EPID was performed in patients with no informed consent for regional anesthesia, age <4 mo, preoperative or postoperative anticoagulation therapy, or anticipated postoperative pulmonary hypertension or significant ventricular dysfunction.

Age, sex, cardiac lesions, surgical procedures, cardiopulmonary bypass and total OR times, and pediatric intensive care unit (PICU) and hospital length of stay were recorded for patients in both SAB and EPID groups. Charts were reviewed and data recorded for all significant changes in vital signs, including heart rate <80% or >120% of baseline (bradycardia and tachycardia, respectively) and systemic arterial blood pressure <80% or >120% of baseline (hypotension and hypertension, respectively). Oxygen desaturation was defined as SpO2 <90% for patients with acyanotic lesions and <90% of baseline for patients with cyanotic lesions. Hypercarbia was defined as PaCO2 >50 mm Hg. All sedative/analgesic interventions were recorded, including the administration of all sedative drugs (SAB and EPID groups), IV opioids (SAB group), and increases in epidural infusions (EPID group).

Patients over the age of 9 mo received premedication with oral midazolam 0.5–0.6 mg/kg approximately 30 min before the induction of anesthesia. After placement of routine monitors, the induction of anesthesia was performed with sevoflurane in 70% nitrous oxygen and oxygen. An IV catheter was inserted, rocuronium was administered, and a tracheal tube was placed. Patients were then placed in the right lateral decubitus position for SAB or EPID.

Patients receiving SAB/general anesthesia had a 2-inch, 22-gauge spinal needle inserted at L3-4 or L4-5. Intrathecal tetracaine and morphine were dosed according to the patient’s age (Table 1). Infants less than 1 yr received tetracaine 2.0 mg/kg and preservative-free morphine 0.007 mg/kg of body weight; children between 1 and 3 yr received tetracaine 1.0 mg/kg and preservative-free morphine 0.007 mg/kg of body weight; children between 4 and 5 yr received tetracaine 0.5 mg/kg and preservative-free morphine 0.007 mg/kg of body weight; and children over the age of 5 yr received preservative-free morphine 0.010 mg/kg of body weight without tetracaine. These dosing regimens were designed to provide high spinal blockade while minimizing hemodynamic changes and postoperative side effects (16,17).


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  		Table 1. Dosing Regimens for Spinal Anesthesia
 
Patients receiving EPID/general anesthesia had an 18-gauge Tuohy needle inserted by the "loss of resistance" technique to facilitate placement of a 20-gauge epidural catheter between T5 and T8. Once the epidural catheter was secured, patients received bupivacaine 0.25% in a dose of 1.25 mg/kg and hydromorphone 0.007–0.008 mg/kg of body weight. Additional doses of bupivacaine 0.25% 0.75 mg/kg were administered every 90 min while the patient was in the OR. In the PICU, these patients received bupivacaine 0.3 mg · kg-1 · h-1 and hydromorphone 0.009 mg · kg-1 · h-1 (Table 2).


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  		Table 2. Dosing Regimens for Epidural Anesthesia
 
All patients were positioned with the head of the OR table approximately 30° down for a minimum of 15 min during placement of arterial and central venous catheters to facilitate cephalad spread of the regional anesthetic. All patients received general anesthesia with a mixture of isoflurane 0.3%–1.5% in oxygen with the intent to maintain mean arterial blood pressure and heart rate between 80% and 120% of baseline. Rocuronium was given for neuromuscular blockade. No systemic opioids were administered intraoperatively. Residual neuromuscular blockade was antagonized on completion of surgery, and tracheal extubation was performed in the OR in all patients.

Sedative and analgesic drugs were administered in the PICU as needed according to the assessment of the bedside nurse and physicians. Age-specific pain scoring systems were used to guide the use of opioids. These included the Wong-Baker Faces Scale for patients over the age of 3 yr and a scoring system based on vital signs, crying, facial expression, and muscle tone for younger patients (18). Sedative drugs were used in combination with opioids at the discretion of the bedside nurse and physicians. For patients with epidural catheters in place, the Pediatric Pain Service was notified when pain was suspected, after which adjustments were made in the epidural infusion.

Statistical analyses of continuous data for each of the groups were done with the Student’s t-test with Bonferroni correction for multiple comparisons. Variance is expressed as standard error of the mean. {chi}2 test (Fischer) was used to determine if the frequency of outcomes was different among groups (significance for P < 0.05).


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 References
 
There were 25 patients in each group. There were no statistical differences between groups with respect to patient age, sex, distribution of congenital heart defects, and surgical procedures (Table 3). The incidence of clinically significant changes in vital signs, oxygen desaturation, hypercarbia, and vomiting was similar in both groups (Table 4). Tracheal extubation was performed in the OR in all patients in the SAB and EPID groups, and no patient required reintubation. Patients in the SAB group received significantly more sedative/analgesic interventions than those in the EPID group (P < 0.01).


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  		Table 3. Patient Demographics, Lesions, and Length of Stay
 

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  		Table 4. Number of Patients with Selected Clinical Endpoints
 
No patient developed systemic hypotension after regional anesthesia. No patient had oxygen desaturation during the 18–24-h PICU stay after surgery. Naloxone, positive pressure ventilation, and tracheal reintubation were not required by any patient.

Ondansetron 0.1 mg/kg IV was given to all patients in the SAB group before tracheal extubation. Six patients in the EPID group received ondansetron 0.1 mg/kg IV postoperatively for nausea and/or vomiting. Four patients in the SAB group and two in the EPID group vomited after surgery.


   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
References
 
We retrospectively reviewed the medical records of patients undergoing open heart surgery under general anesthesia with SAB or EPID to determine which, if either, technique was superior with respect to circulatory stability, postoperative sedation and analgesia, and the incidence of postoperative oxygen desaturation, hypercarbia, and vomiting. Because of our previous institutional experience, wherein regional anesthesia facilitated early tracheal extubation, a comparative study with a control group excluding regional anesthesia was not feasible during this time (9). Our study suggests that SAB or EPID plus general anesthesia is associated with stable vital signs during and after cardiac surgery. In addition, we found a small incidence of oxygen desaturation and hypercarbia postoperatively. The incidence of postoperative vomiting was similar and small in both groups compared with previous studies (8,19). The primary clinical difference between the EPID and SAB groups was that during 24 hr after surgery SAB patients received significantly more sedative/analgesic interventions than those in the EPID group. Accordingly, patients in the EPID group appeared to be more comfortable than those in the SAB group.

The use of epidural and spinal anesthesia in adults and children to attenuate the stress response and decrease morbidity and mortality associated with cardiac surgery is supported by several studies (3–5,7,15,20–22). For example, adult patients receiving thoracic epidural anesthesia for cardiac surgery have reduced serum catecholamine and stress hormone concentrations (2,4–6). In a study of children undergoing open heart surgery, epidural morphine administration attenuated the adverse decrease in T3 (liothyronine) concentration associated with cardiopulmonary bypass (22). Epidural local anesthetics may be more effective than opioids in attenuating the stress response (7). Epidural anesthesia with bupivacaine suppresses the increase in serum catecholamines, glucose, and adrenocorticotropic hormone more effectively than IV fentanyl in infants (8,23). In a study of fetal lambs, total spinal anesthesia completely blocked the stress response to surgical manipulation and cardiopulmonary bypass (20).

In addition to the reduction in surgical stress response, the use of these regional anesthesia techniques during and after cardiac surgery may result in improved pulmonary function, greater circulatory stability, and better postoperative pain control compared with general anesthesia alone and postoperative IV opioid analgesia (2,6,15,24,25). To the extent that regional anesthesia facilitates tracheal extubation in the OR immediately after cardiac surgery, an additional benefit is the avoidance of the deleterious effects of postoperative mechanical ventilation. These include trauma to the larynx and trachea associated with patient movement in the presence of a tracheal tube, barotrauma caused by coughing or endobronchial intubation, accidental extubation, and pulmonary hypertensive crises during suctioning of the endotracheal tube (26). In addition, the expense associated with mechanical ventilation in the postoperative period may be avoided. These benefits must be weighed against the possible adverse effects associated with spinal and epidural anesthesia, such as hypotension, postoperative nausea and vomiting, hypercarbia, and epidural hematoma formation. Finally, the relative risk of epidural hematoma formation in patients receiving SAB versus EPID before heparinization remains unclear. The incidence of epidural hematoma formation has been estimated to be approximately 1:220,000 after SAB and 1:150,000 after EPID (27). An increased incidence associated with EPID may be because larger needles are used and catheters are placed that traverse venous plexi in the epidural space. In addition, epidural hematoma formation may occur during catheter removal, especially in the presence of abnormal coagulation function (28). Recommendations have been made for minimizing the risks of epidural hematoma formation in patients undergoing SAB or EPID, including selecting patients with normal coagulation function preoperatively, delaying surgery in the event of traumatic needle placement, maximizing the time interval between needle placement and heparin administration, and epidural catheter removal only after normal coagulation function has been restored (28,29).

We describe regional anesthesia techniques for cardiac surgery in children. Further studies are needed to clarify the relative benefits of SAB versus EPID with general anesthesia in these patients.


   Acknowledgments
 
The authors would like to acknowledge the contribution of Drs. Gail Boltz and Kristi Peterson, each of whom provided anesthesia for several patients in this study.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 

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Accepted for publication November 29, 1999.




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Lippincott, Williams & Wilkins Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999 HighWire Press