Pain management in the postoperative congenital heart disease patient

Progress in

Pediatric Cardiology Progressin PediatricCardiology4 (1995)169-176

ELSEVIER

Pain management in the postoperative congenital heart disease patient Maureen Strafford” a, Howard Zucker b aNew England bIntensiue

Medical

Center Anestnesiology

Care Unit, Babies

Center,

Tufs LJniMrsi@ School of Medicine, 750 Washington Street, Ziskind 6 Box 298, Boston, MA 02111, USA and Children’s Hospital of New York, Columbia University College of Physicians and Surgeons, 3959 Broadway, Room 2N259, New York, NY 10032, USA

Abstract Postoperative control of pain in infants and children was formerly thought to be of little matter, but data relatively recently developed indicates that, for a variety of reasons, control of pain is of great importance for the pedatric patient. This chapter summarizes some of the data which have led to the contemporary appreciation of the importance of pain control. It also outlines techniques for providing optimal control of pain in the postoperative cardiac patient. Keywords:

Anesthesia; Pain; Cardiac surgery

1. Introduction ‘Systemscontrollingcardiovascularfunction are closelycoupled to systemsmodulating the perceptionof pain. 111’

Children of all ages experience pain. An explosion in pain research over the last decade has elucidated more clearly our understanding of pain mechanisms, appropriate pain assessment, and the safe application of innovative pharmacologic and non-pharmacologic strategies to treat pain in adults and children. It is obviously humane to treat pain. In addition, we now understand that the negative consequences of untreated pain may have profound effects on physiologic homeostasis, and in the case of the post-operative patient, morbidity and mortality may be adversely affected. Advances in pain treatment have finally found application in the pediatric population. Despite active research and discussion, children continued to have their pain underrecognized, undertreated and misun-

*Corresponding author, Tel.: + 1 617 6366046; Fax + 1 617 6368384.

derstood. This discussion will highlight the background behind the poor treatment of pain in children, will discuss some of the innovative approaches available, and will review practical approaches to effective and safe pain management for children of all ages that are now available to the clinician. 2. Historical background ‘Pediatric patients seldom need medications for relief of pain. They tolerate discomfort well. The child will say he/she does not feel well, or that he/she is uncomfortable, or that he/she wants his parents, but often he will not relate this unhappiness to pain’ [2]. Drs. Swafford and Allan wrote this statement in 1968 which clearly reflected the widely-held belief that children did not require analgesic treatment. This practice was accepted and practiced clinically as demonstrated in their study that only 26 of 180 children received postoperative opioids after major surgery while in an intensive care unit setting. In 1983, Mather and Mackie demonstrated a clear pattern of undertreatment in children [3]. After major abdominal and

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thoracic surgery, only 16% of children had an analgesic order written, and because pm was often added to the medication order, nurses only administered appropriate opioid medication 39% of the time. PRN was often interpreted as ‘please restrict narcotics’. In addition, doses ordered were often inappropriately low with respect to dosage and time interval. When children and adults were compared, Beyer was the first to show in 1983 that all adults had a postoperative opioid ordered after open heart surgery, while only 44 of the 50 children surveyed had similar orders [4]. During the initial postoperative period when pain was most acute, adults received a mean of ten doses while children only received 3.2 doses, and often a non-opioid or an analgesic at an inappropriately low dose. In 1989, Schechter demonstrated that adults still received 1.5-3 times the doses children received after similar surgical procedures [5]. While acute post-operative pain is more aggressively treated presently, a survey in 1992 continued to demonstrate persistent treatment of pain in children after cardiac surgery. The most commonly ordered analgesic was 0.1 mg/kg q3h of morphine, and this treatment regimen commonly resulted in poor pain control [6]. Well-entrenched misunderstandings about pediatric pain abound and include misconceptions about pain in general and a poor understanding of appropriate pediatric pharmacokinetic and pharmacodynamic data. Pain is often seen as a diagnostic aid and not as a symptom that requires attention and treatment. It is worth reviewing some of these misconceptions and reviewing scientific data which can clarify some of these issues as a critical part of progress towards effective pediatric pain management. ‘Children, especially neonates and infants, do not feel pain the same as adults do and even if they do experience pain, they will have no memory of it.’

There is now convincing evidence that children of all ages experience pain and that despite the immaturity of the neuroanatomical systems subserving pain pathways, that even the premature infant experiences pain. Cutaneous sensory receptors are present between the 7th and 20th week of gestation and these receptors may even be more dense than in the older child. The neocortex develops (8-20 weeks), followed by cortical synapses (20-24 weeks), and clinical brain function (28 weeks). This is a fully functional system at this point and it becomes more efficient after the process of myelination is complete. Despite incomplete myelination at birth, neonates are absolutely capable of pain perception. In fact, the short distance that a pain impulse must travel in the smaller infant counterbalances the immaturity of myelination. Fascinating laboratory research in young animals has de-

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monstrated that peripheral nerve injury in the neonate can alter connections in the cortex, resulting in permanent distortion of that body area’s representation in the brain [7,8]. ‘Children become easily addicted to opioids.’

It is important to understand the differences between addiction or psychological dependence, tolerance, and physical dependence when discussing the appropriate use of opioids. The fear of addiction is a real fear that care-givers, patients and their families often have and which stands in the way of appropriate treatment for severe pain [9]. Addiction is a state, psychic and sometimes also physical, characterized by behavioral and other responses that always include a compulsion to take the drug on a continuous or periodic basis in order to experience its psychic effects and sometimes to avoid the discomfort of its absence. Tolerance is the patient’s need for increasing amounts of an opioid to achieve the same degree of pain relief over time. Physical dependence will develop as the patient becomes more tolerant to an opioid and if the drug is withdrawn abruptly, signs and symptoms of withdrawal will occur. The occurrence of withdrawal signs does not imply addiction, but rather illustrates the expected phenomenon of opioid tolerance and physical dependence. The risk of true addiction in children, even older children and adolescents, is extremely rare, probably less than l%, and the administration of appropriate opioid therapy for pain is not the major factor in the development of opioid addiction. Children who have received opioids for pain relief do not show problems with addiction in later life [lo]. The American Pain Society has made the statement that ‘there is no evidence that preadolescent or adolescent children are at a higher risk for developing psychological dependence (addiction) than the general population when given opioids for the management of pain’ [ll]. ‘Respiratory depression is a common problem in children treated with opioids.’

While respiratory depression is a well-recognized side-effect of opioid analgesia, lack of clear knowledge about the developmental pharmacology and pharmacokinetics of opioids in infants and children has resulted in an exaggerated fear of this side-effect. Morphine and most analgesics are conjugated in the liver, and because newborns have immature conjugation systems and immature cytochrome P-450 catalysis, these drugs are metabolized in a slower fashion. Glomerular filtration is decreased in the newborn. By 3 months of age, these systems are functioning at adult levels and pharmacokinetic data supports these

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adaptations. Morphine’s elimination half-life is more than twice as long in newborns in the first week of life and even longer in premature infants, when compared to older children [12,13]. There may be age-related differences in the number and subtypes of mu receptors (responsible for respiratoq depression), which supports the observation that newborns may be less sensitive to the analgesic effects of morphine but more sensitive to its respiratory depressant effects [14]. Because less morphine is protein bound in the newborn (20% in the neonate less than 5 days of age compared to 35% in adults), more drug is available to cross the blood-brain barrier and exert respiratory depressant effects [15]. Infants over 3 months of age have been shown to have no greater respiratory depression than older children and adults with morphine [16]. In children aged 11 days to 7 years, morphine did not affect respiration, as measured by arterial pco2, differently than in adults [17]. The likelihood of life-threatening respiratory depression in adults is probably about 0.09% [18]. Studies of respiratory depression in children through adolescence reveals an incidence of O-5% 119,201. Appropriate dosing and careful cardiorespiratory monitoring can result in safe and effective opioid administration. Low dosing is not necessarily safe dosing because pain may persist and repeated dosing to achieve better pain control may eventually lead to accumulation and delayed respiratory depression. The initial dose is most important and the patient’s response should be carefully observed and titration followed. As illustrated in Fig. 1, an initial bolus dose will place the patient in a comfortable analgesic range. If a continuous infusion is utilized, the patient will remain comfortable at a lower dose and may avoid the oversedation under treatment cycling that is often seen in intermittent dosing regimens. ‘The child is frightened, hungry, anxious, missing his/her parent but not really in pain.’

This statement illustrates the difficulty caretakers experience in assessing pain in the pediatric patient, especially the infant and pre-verbal child. While fear, anxiety, and other emotional aspects of behavior may be present with acute pain, difficulties in pain assessment should not preclude appropriate pharmacologic treatment. Pain assessment tools are now available that are safe and developmentally appropriate. Nursing must play a critical role in the use of these tools both for assessment before drug administration and as a tool to assess the patient’s response to the drug. Both behavioral and physiologic variables can be incorporated into different assessment tools. No one assessment tool is ideal for every patient, but there are now a variety of tools that have been validated in

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Analgesia Pain 0

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(A) Intermittent intravenous bolusing results in deep sedation at peak levels after a dose followed by prolonged periods of pain between q4h doses. Coma Analgesia Pain 0

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(B) Intramuscular administration results in less fluctuations in opioid effects but pain and analgesia do alternate. Coma

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(C) Continuous intravenous infusions result in a more constant level of analgesia but slow accumulation may result in excessive sedation and should be considered. Fig. 1. Opioid administration: effects of different delivery modes on pain-sedation-analgesia. (A): Intermittent intravenous bolusing results in deep sedation at peak levels after a dose followed by prolonged periods of pain between q4h doses. (Bl: Intramuscular administration results in less fluctuations in opioid effects but pain and analgesia do alternate. CC): Continuous intravenous infusions result in a more constant level of analgesia but slow accumulation may result in excessive sedation and should be considered.

children of all ages. The tool chosen should incorborate ease of use and availability. Caretakers will be more likely to use the tool consistently resulting in more accurate assessment and effective treatment. The reader is referred to more extensive discussions of assessment for review [21,22]. The approach to

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appropriate assessment by a caretaker must include the knowledge that ‘pain behaviour in children is not the pain behavior of ‘little adults’. It is not just an adult experience in a smaller person, or a smaller amount of an otherwise adult experience [23]. 3. Why treat pain? Beyond the obvious need for compassionate pain relief, recent scientific literature has dramatically indicated an important role for modulation and ablation of the stress response that accompanies a painful stimulus. The well-described stress response to pain includes the release of catecholamines, catabolism, hypercoagulability, vasoconstriction and immunosuppression [24]. The literature has documented reduced morbidity with adequate pain control. Oxygen consumption was studied in children after cardiac surgery who were intubated [25]. Morphine was given via intermittent bolus (0.05 mg/kgl versus continuous infusion (0.1-l pg/kg/min). The continuous infusion group had significantly lower oxygen consumption with similar pain scores in both groups. Since pain relief in the cardiac surgery patient obviously begins in the peri-operative period with initiation of general anesthesia, different anesthetic techniques have been studied to determine their effect on the stress response during surgery. Anand and Hickey studied neonates undergoing cardiac surgery using a high-dose opioid technique (sufentanil followed by continuous infusion postoperatively) with a halothane morphine anesthetic. The high-dose opioid group showed ablation of the stress response with less hyperglycemia, metabolic acidosis, DIC and sepsis, and a significant decrease in mortality and morbidity [26]. High-dose fentanyl has been shown to decrease the fibrillatory threshold and to maintain cardiovascular stability in neonates undergoing repair of hypoplastic left heart syndrome [27]. The cardiac patient after surgery may have pain from sternotomy and/or thoracotomy incisions, chest tubes, endotracheal tubes and repeated post-operative painful procedures, such as the placement and/or removal of chest tubes and peripheral venous and arterial lines. Pain from chest incisions, especially thoracotomy incisions, may contribute to post-operative ventilatory limitation. Atelectasis, pneumonia and prolonged ventilatory support may ensue from respiratory compromise. Adults after cardiac surgery show a high incidence of left lower lobe atelectasis [28], and children are equally prone to this problem. Effective analgesia using regional techniques such as administration of epidural opioids or continuous infusion of opioids and/or local anesthetics via epidural catheters directs analgesic drugs directly to the af-

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fected nerves and results in superb analgesia without some of the less desirable effects of systemically administered opioids. Placement of catheters may be limited, however, by the risks of systemic heparinization and possible epidural hematoma that open heart bypass patients undergo. This topic will be discussed further in a later section. 4. When to treat pain? The role of pre-emptive analgesia When a painful stimulus occurs, the peripheral nocioceptors are sensitized. The central processing of afferent input is altered and may lead to prolongation and even amplification of post-operative pain. In laboratory studies, central sensitization of the dorsal horn neurons may be eliminated or decreased by preventing a noxious stimulus from reaching the CNS. Treatment for pain before the painful stimulus is applied or pre-emptive analgesia may play a significant role in modifying the pain and stress response and dramatically decrease the need for post-stimulus or postoperative pain treatment. Many clinical studies have examined the role of regional anesthesia techniques using local infiltration of anesthetics, spinal or epidural local anesthetics and opioids and other regional nerve blocks to determine the effect on postoperative pain medication requirements in patients. Tverskoy studied patients having inguinal hernia repair with either spinal anesthesia, general anesthesia, or general anesthesia with lidocaine injected into the surgical field prior to incision. Both groups of patients had lower pain scores if they received local anesthesia prior to incision compared to the general anesthesia group alone. The differences in pain scores persisted in some patients for as long as 10 days [29]. Pre-emptive analgesia has been studied less in children. In children receiving local anesthetic block for hernia repair, children who received the block before incision had better pain relief and less need for opioids post-operatively if they received the block after incision [30]. The study of pre-emptive analgesia is underway in many different areas of patient care and should provide interesting information about effective and safe analgesia [31,32]. 5. Approach to pain treatment While there is ample evidence that pain relief improves patient outcome, children undergoing cardiac surgery often have inadequate or inappropriate management of their pain [6]. For many of the reasons outlined above, the post-operative congenital heart disease patient deserves close attention to this issue because of the profound effect the stress response

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may have on cardiovascular homeostasis, pulmonary vascular reactivity, catabolism, oxygen consumption and pulmonary mechanics. The postoperative patient is often mechanically ventilated, paralyzed, and still under the effects of general anesthesia when he arrives in the ICU for postoperative care. Assessment is therefore difficult and often relies on physical signs such as tachycardia and hypertension - signs that may be signs of pain as well as a reflection of cardiovascular status and/or the administration of concomitant drug therapy. Sedation is often a goal for the patient in the ICU setting and the use of sedatives may obscure pain. A sleeping child may still be experiencing pain and for many children, lack of interactive play or activity may be the only sign of ongoing pain. While anxiolytic treatment is helpful as an adjuvant treatment for children after surgery, anxiolysis alone does not provide analgesia and is sub-optimal as a sole treatment. This discussion will focus on a practical approach to pain management in the postoperative congenital heart disease patient, and will discuss pharmacologic as well as non-pharmacologic techniques that may provide the clinician with a workable approach to pain management. In addition, the concepts of tolerance, dependence, sedation treatment and possible withdrawal after prolonged opioid treatment in the ICU will be reviewed. 6. Pharmacologic

treatment of pain

6.1. Non-opioid analgesics

While opioids remain the mainstay of treatment for moderate to severe post-operative pain, the use of non-opioid analgesia should be considered as an adjuvant drug therapy with an opioid or during the later stages of recovery when pain intensity has decreased. Acetaminophen. A safe, effective, widely used analgesic and antipyretic. The immature hepatic metabolism of the newborn may protect against toxic metabolites of the drug. Doses of lo-15 mg/kg orally or 20-25 mg/kg rectally q4h result in safe plasma levels and provide pain relief similar to non-steroidal anti-inflammatory drugs (NSAIDs). Rectal administration may result in delayed peak levels and cannot be relied upon for rapid onset of analgesia [33]. NSAIDs are available in a variety of different formulations. The pharmacodynamics and pharmacokinetics of this class of drug are similar to adults in children beyond the newborn period. Acetylsalicyclic acid &SA). An excellent analgesic for inflammatory pain. Neonates have a prolonged elimination but adult pharmacokinetics are reached by the first year of life. The association of ASA administration with Reye’s syndrome, i.e. platelet and

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side effects, have limited its pediatric

Ibuprofen, naproyn, indomethicin, choline magnesium ttialicylate and ketorolac. All are NSAIDs that

have been utilized for post-operative pain. NSAIDs may cause gastrointestinal side-effects, renal and platelet impairment and limit their use in certain patients. However, they are also potent adjuvants to opioid analgesia and, when used with an opioid, may result in decreased opioid requirements [34]. For example, rectal ibuprofen reduced the need for opioid analgesics in a postoperative study by 30%. Indomethicin used in a continuous i.v. infusion resulted in excellent analgesia with patients reporting better pain relief than the use of a pm opioid alone 1351. Ketorolac has become widely used as a post-operative analgesic. Doses of 1 mg/kg loading followed by 48 h of 0.5 mg/kg q6h results in excellent analgesia and a decrease in opioid analgesia. 6.2. Opioid analgesics

Opioids are effective for moderate to severe pain and are well-studied in children of all ages. The developmental pharamcokinetics of morphine have been discussed earlier. Other opioids, such as fentanyl, sufentanil, meperidine and methadone, are all biotransformed in the liver, so delayed elimination may occur until hepatic enzymatic maturity is reached. Opioids have a variety of routes of administration: oral, i.v., i.m., s.c., rectally, transdermally, transmucausally or at new sites such as the subarachnoid or epidural space. It is counter-productive to administer an analgesic to a child in a painful way. Children will often refuse i.m. intermittent morphine to avoid the painful ‘shot’. Intermittent dosing can lead to a cycling effect of under and oversedation. The use of continuous opioid infusions and PCA (Patient Controlled Analgesia) will result in more reliable plasma levels of opioid and consistent analgesia. Continuous infusions of morphine in the postoperative period can be safe and effective. A loading dose of 0.05-0.1 mg/kg will often place the patient in an analgesic range without oversedation. A continuous infusion of 25-40 pg/kg/h is started after a loading dose and adjusted to patient comfort. Lower doses of lo-15 pg/kg/h should be utilized in the young infant (3-6 months). Fentanyl is widely used in postoperative cardiac patients. Effective analgesia can be obtained with doses of l-3 pg/kg/h. High-dose fentanyl infusions (lo-20 pg/kg/h) may blunt pulmonary vascular reactivity and maintain cardiovascular stability. Fentanyl’s short half-life may result in rapid development of tolerance and should be anticipated for prolonged use. Meperidine is less commonly used in children. Because the metabolite, normeperi-

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dine, may cause seizures, continuous infusions of this drug are not used.

sidered as part of a comprehensive pain management plan.

6.3. Patient-controlled analgesia (PCA)

6.5. Regional analgesia /regional anesthesia

Opioid delivery via a PCA model has found wide acceptance in the pediatric population in recent years. With PCA, the patient self-administers small boluses of drug that are delivered via a programmed pump. Dosages are set and appropriate ‘lock-out’ periods are established during which the patient cannot receive a bolus. PCA may also be used with a background continuous infusion. Morphine boluses are usually 0.02-0.03 mg/kg/dose with a lockout interval of 7-10 min. The use of a basal infusion rate (0.01-0.02 mg/kg/h) often permits the patient to have a comfortable sleep, uninterrupted by the need for the patient to administer boluses. However, more episodes of hypoxemia have been described with the use of basal infusion [36]. PCA can be effectively used with an adjuvant NSAID such as ketorolac, resulting in excellent analgesia and decreased opioid requirements and side-effects. A review of PCA in 1589 patients demonstrated an excellent safety record with only two episodes of significant respiratory depression which occurred with concurrent administration of anti-histamines for side-effect therapy [37]. If these drugs are needed, the PCA pump should be stopped before, during, and after administration to avoid this problem with sedative drugs. Side-effects of opioids are increased in PCA patients [38]. PCA can be used in young children (2 7 years) with proper pre-operative preparation. Parents and nurses should not influence the child’s use of the pump, although studies have examined the role of parent and nurse-controlled or assisted analgesia [39,401. PCA has been shown to have several advantages over the traditional intermittent bolus administration of morphine. These include patient satisfaction, sense of mastery and control, a decrease in the delay between request and delivery of an analgesic and improved pulmonary complications [41,42]. 6.4. Adjuzmt anesthetics

drugs: benzodiazepines and local

Fear often accompanies and exacerbates pain, especially in children, The use of anxiolytics such as midazolam can be an effective adjuvant to effective pain management but should not replace the use of effective analgesics since these medications have little analgesic effect. Continuous infusions may be helpful but tolerance can develop to this group of drugs as well and should be anticipated and managed appropriately. Local anesthetic infiltration into wounds, the use of EMLA (Eutectic Mixture of Local Anesthetics) for venipuncture and chest tube removal should be con-

The application of local anesthetics and/or opioids into the neuroaxis as a pain control method has gained increasing acceptance. Since these techniques have been used for years in adults, the pediatric literature is smaller but increasingly supportive of these techniques for their safety and efficacy. Morphine can easily be administered to children into the epidural space via the caudal hiatus, which is an easily located anatomic landmark. Children given caudal morphine with local anesthetic (bupivicaine) had excellent analgesia compared to i.v. medication [43]. Multiple studies in children have demonstrated effective analgesia that is also cost-effective. For example, a retrospective review of children having fundoplication with either epidural morphine or i.v. morphine had less morbidity (especially respiratory depression) and decreased overall cost ($12580 vs. $17658) when epidural analgesia was utilized. In addition, only 16% of the epidural group required postoperative ventilation vs. 53% receiving general anesthesia alone [44]. Analgesia from a bolus dose of epidural morphine (0.05-0.10 mg/kg/dose) varies from 4 h to 24 h, with a mean duration of 10 h [45]. For many uncomplicated open-heart patients (e.g. ASD), the requirement for additional postoperative parenteral opioids is dramatically reduced and the transition to oral medication is facilitated. Since delayed respiratory depression (> 24 h) has been reported with epidurally administered morphine, appropriate cardiorespiratory monitoring is recommended [46]. The combination of local anesthetic with opioid permits each drug to be given in a lower dose while still providing optimal analgesia. While opioids and/or local anesthetics can be administered as a ‘one-shot’ application, the use of continuous infusions after catheter placement provides longer postoperative analgesia and better titration. However, studies have been limited in pediatric cardiac surgery. The use of systemic heparinization in open heart surgery patients and the consequent risk of epidural hematoma formation appears to be low in heparinized adults [47] but studies are scarce in children. Studies using continuous lumbar epidural infusions of morphine in postoperative pediatric cardiac patients demonstrated a decreased need for parenteral opioids, decreased ventilatory requirements, and less time in the ICU [48]. While multi-institutional studies of regional analgesia in pediatric patients have confirmed its safety and efficacy, pediatric cardiac patients need further study. Obviously, the application of regional analgesia depends on the availability of an anesthesia team that is knowledgeable and technically skillful with these modalities.

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treatment of pain

Behavioral techniques, such as biofeedback, hypnosis, guided imagery, massage therapy, physical therapy, relaxation/distraction techniques, and other non-pharmacologic techniques such as acupuncture and TENS units (Transcutaneous Electrical Nerve Stimulation) have found wide applicability in the management of both acute and chronic pain in children. A classic study in 1964 demonstrated that preoperative patient education about what to expect during a planned hospitalization alone reduced postoperative analgesic requirements [49]. Obviously, a developmentally appropriate preparation for pediatric patients would be beneficial. Non-pharmacologic techniques are best introduced and taught prior to an anticipated painful experience. They are less optimal in the midst of a painful event. Children benefit from these techniques but they are often underutilized because nurses, physicians and parents are unfamiliar in ‘how-to-do’ these various techniques. They find optimal application in combination with pharmacologic therapy for acute postoperative pain. 8. Special issues: sedation and withdrawal

in the ICU

Treatment with potent opioids and other adjuvant drugs requires an understanding of drug tolerance, physical dependence and withdrawal. These terms have been defined previously but are often misunderstood or ignored in patients treated for pain and anxiety in the ICU. Physical dependence and the possibility of withdrawal with abrupt cessation of the opioid has been described within 5 days of continuous treatment [50-531. In a survey regarding sedation of pediatric intensive care fellowship programs, only a minority of respondents viewed withdrawal as a problem (6.9%). When asked specifically about withdrawal, 61.8% reported that withdrawal was present but that treatment was instituted only after symptoms were prominent. Only 23.5% of the centers implemented preventive tapering regimens in patients at risk of withdrawal [54]. It is most likely that untreated withdrawal is more common in the pediatric ICU setting and may contribute to postoperative morbidity secondary to the increased physiological stress accompanying withdrawal. 9. Summary The revolution in pain management has found wide application in many areas of pediatric care. Because pre-conceived misconceptions about pain recognition and treatment still persist, many children with heart disease, especially in the postoperative period, may

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continue to go untreated or are inadequately treated because pain treatment may be seen as a risk to maintaining cardiovascular stability. The scientific literature supports the opposite viewpoint. We now have new drugs, new delivery modes and new knowledge about the need for appropriate recognition and treatment of pain in all children, especially the cardiac patient, in whom cardiovascular homeostasis is vital. Future research directed specifically towards pain treatment in the congenital heart disease patient should add to our knowledge and optimally improve postoperative morbidity and mortality. References 111 Randich A, Maixner W. Interactions between cardiovascular and pain

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