Postoperative Analgesia After Spinal Blockade in Infants and Children Undergoing Cardiac Surgery

Management of routine postoperative pain for children undergoing cardiac surgery: a Paediatric Acute Care Cardiology Collaborative Clinical Practice Guideline

BACKGROUND

Pain following surgery for cardiac disease is ubiquitous, and optimal management is important. Despite this, there is large practice variation. To address this, the Paediatric Acute Care Cardiology Collaborative undertook the effort to create this clinical practice guideline.

METHODS

A panel of experts consisting of paediatric cardiologists, advanced practice practitioners, pharmacists, a paediatric cardiothoracic surgeon, and a paediatric cardiac anaesthesiologist was convened. The literature was searched for relevant articles and Collaborative sites submitted centre-specific protocols for postoperative pain management. Using the modified Delphi technique, recommendations were generated and put through iterative Delphi rounds to achieve consensus.

RESULTS

60 recommendations achieved consensus and are included in this guideline. They address guideline use, pain assessment, general considerations, preoperative considerations, intraoperative considerations, regional anaesthesia, opioids, opioid-sparing, non-opioid medications, non-pharmaceutical pain management, and discharge considerations.

CONCLUSIONS

Postoperative pain among children following cardiac surgery is currently an area of significant practice variability despite a large body of literature and the presence of centre-specific protocols. Central to the recommendations included in this guideline is the concept that ideal pain management begins with preoperative counselling and continues through to patient discharge. Overall, the quality of evidence supporting recommendations is low. There is ongoing need for research in this area, particularly in paediatric populations.

Efficacy of paravertebral block in "Fast-tracking" pediatric cardiac surgery - Experiences from a tertiary care center

Introduction:

Fast tracking plays a crucial role in reducing perioperative morbidity and financial burden by facilitating early extubation and discharge from hospital. Paravertebral block (PVB) is becoming more popular in paediatric surgeries as an alternative to epidural and caudal analgesia. There is scarcity of data regarding the efficacy and safety of PVB in paediatric cardiac surgery.

Methods:

We performed a review of records of paediatric cardiac patients who underwent cardiac surgery under general anaesthesia with single shot PVB and compared the analgesia and postoperative outcomes with matched historical controls who underwent cardiac surgery with same anaesthesia protocol without PVB.

Results:

The data from 200 children were analysed. 100 children who received paravertebral block were compared with a matched historical controls. The median time to extubation was shorter in the PVB group (0 hr, IQR 0-3 hrs) compared to the control group (16 hrs, IQR 4-20 hrs) (P value 0.017*). Intraoperative and postoperative fentanyl requirement was much lower in the PVB group (3.49 (0.91)) compared to the control group (9.86 (1.37)) P value <0.01*. Time to first rescue dose of analgesic was longer (7 hrs vs 5 hrs, P 0.01*), while time to extubation and duration of ICU stay were significantly less in PVB group . Mean postoperative pain scores were significantly lower in the PVB group at the time of ICU admission (0.85 vs 3.12, P 0.001*) till 4 hours (2.11 vs 3.32, P 0.001*).

Conclusion:

PVB provides an effective and safe anaesthetic approach which can form an important component of “fast-track” care in paediatric cardiac surgery.

A Minimal Opioid Postoperative Management Protocol in Congenital Cardiac Surgery: Safe and Effective

There is evidence that reducing opioid exposure in children undergoing cardiac surgery may enhance postoperative recovery. We aimed to describe a minimal opioid postoperative management protocol in children undergoing cardiac surgery and our early outcomes with this strategy. We reviewed the medical records of children (6 months-18 years) who underwent elective cardiac surgery through a median sternotomy with cardiopulmonary bypass at our institution between 2016 and 2018. All patients were managed postoperatively using a standardized protocol. 101 children (median age 5 years) were included and 85% were extubated in the operating room. Although most patients (96%) received opioids postoperatively, opioid requirements decreased steadily over time, with 88%, 58%, and 18% of children receiving opioids on postoperative day 1, 2, and 3, respectively; 41% received no opioids after postoperative day 1. The median cumulative opioid exposure was 0.25 morphine milligram equivalents per kg (interquartile range, 0.10-0.75). Greater than mild pain was rare (<10%) at each time point. The rates of operative mortality and major complication were 0% and 3%, respectively. The median postoperative length of stay was 3 days, and 13% required readmission within 30 days. Age, cardiopulmonary bypass time, and number of benzodiazepine doses were independently associated with cumulative opioid exposure. Any complication, chest tube time, and higher STAT Category were independently associated with prolonged postoperative length of stay. A minimal opioid postoperative management protocol can be safe and effective in children undergoing cardiac surgery. Future prospective studies are needed to determine optimal practice and patient selection.

Pediatric Cardiac Surgery and Pain Management: After 40 Years in the Desert, Have We Reached the Promised Land?

Pain prevention in the pediatric population is mandatory and an integrative aspect of medical practice. Optimal pain management is the right of all patients and the responsibility of all health professionals. The key to adequate pain management is assessing its presence and severity, identifying those who require intervention, and appreciating treatment efficacy. The population of pediatric patients undergoing cardiac surgery is unique in both clinical severity and hemodynamic response to painful stimuli, thus making pain management even more challenging. In this review, we will describe the different pain assessment tools as well as intra- and postoperative regimens of pain management.

Pain outcomes in children who received intrathecal vs intravenous opioids for pain control following major urologic surgery: a retrospective review

BACKGROUND

Intrathecal (IT) opioid administration has been associated with postoperative benefits including reduced pain and opioid use in children. However, the postoperative benefits and risks of IT opioid administration during major urologic surgery in children remain unclear.

AIM

The aim of this study was to compare postoperative pain and adverse event outcomes among children who received IT vs intravenous (IV) opioids during major urologic surgery.

METHODS

We reviewed the medical records of children 3-17 years of age who underwent ureteroneocystostomy or pyeloplasty between 2006 and 2012. Electronically captured anesthetic and surgical data, postanesthesia care recovery unit (PACU) and nursing flowsheets, and daily progress notes through hospital discharge were reviewed. Analgesic techniques (i.e., IT or IV patient/nurse controlled opioids), all analgesic drugs and doses were recorded. Outcome measures included pain scores, need for rescue analgesics, opioid-related adverse events, and their treatments.

RESULTS

Seventy-seven children received IT opioids and 51 received IV opioids. More children in the IV group required rescue analgesics and had higher pain scores at PACU discharge. Children in the IV group required rescue opioids more frequently than the IT group from 0 to 8 h and 8 to 16 h after PACU discharge, but rates were similar by 16-24 h 70% of children in IT group transitioned directly to oral opioids. Seven IT placements were considered as failed due to early need for rescue opioids. Four (8%) of the IV group and seven (9%) of the IT group experienced oxygen desaturation. Two of these, both in IT group required naloxone and one was admitted to ICU for observation. The IT group experienced a higher incidence of pruritus, constipation and hypotension.

CONCLUSION

We observed better postoperative pain control in children who received IT vs IV opioids for the first 16 h with no discernible difference thereafter. The intrathecal group experienced higher incidences of pruritus, constipation, and hypotension.

The efficacy of the COMFORT score and pain management protocol in ventilated pediatric patients following cardiac surgery

BACKGROUND AND OBJECTIVES

An optimal scoring system for pain assessment in pediatric intensive care is necessary to determine the efficacy of analgesics. We assess the COMFORT scale in postoperative ventilated children and study the effect of pain and sedation protocols on their outcomes.

PATIENTS AND METHODS

We included postoperative ventilated patients. The unit-based pain management protocol was used. The assessment of the COMFORT and FLACC scales was performed by 2-nurses at 2-h intervals on the day of surgery and at 4-h intervals during the first 2-postoperative days or until the patient was ex-tubated. The patients' outcomes were compared with age-matched and RACHS score matched patients prior to the application of the pain protocol.

RESULTS

One-hundred-ten prospective patients were included. The mean age and weight was 24 months and 9.8 ± 8.4 kg, respectively. There was a weak, statistically significant correlation between the COMFORT and FLACC scales, with a range of (r = 0.01-0.7). The COMFORT scale demonstrated good internal consistency, with a Cronbach's alpha of 0.75. The mean ventilation days were 1.3 ± 3, with a mean ICU and hospital stay of 5 ± 5 and 10 ± 9 days, respectively. The 110 patients were compared to 50 retrospective matching patients. The prospective group demonstrated statistically less ventilation days, ICU stay time and hospital stay time, with P-values of 0.0004, 0.001 and 0.0003, respectively.

CONCLUSION

The COMFORT scale is a valuable and reliable pain assessment tool for use in postoperative ventilated pediatric patients. The implementation of a pain and sedation protocol decreased the incidence of withdrawal and the duration of mechanical ventilation as well as ICU and hospital stays.

Immediate rescue designs in pediatric analgesic trials: a systematic review and meta-analysis

BACKGROUND

Designing analgesic clinical trials in pediatrics requires a balance between scientific, ethical, and practical concerns. A previous consensus group recommended immediate rescue designs using opioid sparing as a surrogate measure of analgesic efficacy. The authors summarize the performance of rescue analgesic designs in pediatric trials of four commonly used classes of analgesics: opioids, nonsteroidal antiinflammatory drugs, acetaminophen, and local anesthetics.

METHODS

MEDLINE, Embase, CINAHL, The Cochrane Library, and Web of science were searched in April 2013. The 85 studies selected were randomized or controlled clinical trials using immediate rescue paradigms in postoperative pain settings. A random-effects meta-analysis was used to synthesize predefined outcomes using Hedges' g. Difference between the means of the treatment arms were also expressed as a percentage of the corresponding value in the placebo group (placebo-treatment/placebo). Distributions of pain scores in study and control groups and relationships between opioid sparing and pain scores were examined.

RESULTS

For each of the four study drug classes, significant opioid sparing was demonstrated in a majority of studies by one or more of the following endpoints: (1) total dose (milligram per kilogram per hour), (2) percentage of children requiring rescue medication, and (3) time to first rescue medication (minutes). Pain scores averaged 2.4/10 in study groups, 3.4/10 in control groups.

CONCLUSIONS

Opioid sparing is a feasible pragmatic endpoint for pediatric pain analgesic trials. This review serves to guide future research in pediatric analgesia trials, which could test whether some specific design features may improve assay sensitivity while minimizing the risk of unrelieved pain.

Pain management in newborns

As a standard of care for preterm/term newborns effective pain management may improve their clinical and neurodevelopmental outcomes. Neonatal pain is assessed using context-specific, validated, and objective pain methods, despite the limitations of currently available tools. Therapeutic approaches reducing invasive procedures and using pharmacologic, behavioral, or environmental measures are used to manage neonatal pain. Nonpharmacologic approaches like kangaroo care, facilitated tucking, non-nutritive sucking, sucrose, and others can be used for procedural pain or adjunctive therapy. Local/topical anesthetics, opioids, NSAIDs/acetaminophen and other sedative/anesthetic agents can be incorporated into NICU protocols for managing moderate/severe pain or distress in all newborns.

Pain status and sedation level in Chinese children after cardiac surgery: an observational study

AIMS AND OBJECTIVES

This study explored current pain status, sedation level and their trajectories in Chinese children after cardiac surgery. Background.  Pain and sedation management are fundamental care practices in the critical care setting, yet they both are frequently under-implemented for children after major surgery.

DESIGN

Repeated observational design.

METHODS

This study was conducted in a paediatric medical centre in Shanghai, China where 170 children who underwent cardiac surgery were recruited. Pain was measured with the face, legs, activity, cry, consolability scale and sedation levels with the COMFORT Behaviour Scale at 18 fixed time-points for three consecutive postoperative days. Results.  The study indicated that 95 children (55·9%) received continuous opioids for pain relief, and 61 children (35·9%) received no analgesics. Multiple sedatives were used for these children, including bolus phenobarbital for 117 children (68·8%), phenergan for 81 children (47·6%) and midazolam for three children (1·8%). The mean pain scores significantly decreased throughout the operation day (POD-0) to the 2nd postoperative day (POD-2) with the lowest score on POD-2. Less than 5% of pain assessments were identified as moderate to severe across all 2815 observations. The sedation scores significantly increased through POD-0 to POD-2 with the highest score on POD-2. The rate of over-sedation was 50·3% with <1% under-sedation occurring among all the observations. Results also suggested that the length of stay in the cardiac intensive care unit was a predictor of increased analgesic usage in the critical care setting (odds ratio: 1·72).

CONCLUSIONS

Usage of analgesic and sedative agents in cardiac intensive care unit was variable and children experienced low pain scores but a high rate of over-sedation, indicating that healthcare providers should address ways to improve postoperative pain and sedation management in this population.

RELEVANCE TO CLINICAL PRACTICE

The pain and sedation status for children after cardiac surgery changed across the postoperative days. Healthcare providers should be trained in the use of reliable tools to accurately monitor children's pain and sedation levels.

Neuraxial analgesia in neonates and infants: a review of clinical and preclinical strategies for the development of safety and efficacy data

Neuraxial drugs provide robust pain control, have the potential to improve outcomes, and are an important component of the perioperative care of children. Opioids or clonidine improves analgesia when added to perioperative epidural infusions; analgesia is significantly prolonged by the addition of clonidine, ketamine, neostigmine, or tramadol to single-shot caudal injections of local anesthetic; and neonatal intrathecal anesthesia/analgesia is increasing in some centers. However, it is difficult to determine the relative risk-benefit of different techniques and drugs without detailed and sensitive data related to analgesia requirements, side effects, and follow-up. Current data related to benefits and complications in neonates and infants are summarized, but variability in current neuraxial drug use reflects the relative lack of high-quality evidence. Recent preclinical reports of adverse effects of general anesthetics on the developing brain have increased awareness of the potential benefit of neuraxial anesthesia/analgesia to avoid or reduce general anesthetic dose requirements. However, the developing spinal cord is also vulnerable to drug-related toxicity, and although there are well-established preclinical models and criteria for assessing spinal cord toxicity in adult animals, until recently there had been no systematic evaluation during early life. Therefore, in the second half of this review, we present preclinical data evaluating age-dependent changes in the pharmacodynamic response to different spinal analgesics, and recent studies evaluating spinal toxicity in specific developmental models. Finally, we advocate use of neuraxial drugs with the widest demonstrable safety margin and suggest minimum standards for preclinical evaluation before adoption of new analgesics or preparations into routine clinical practice.

Spinal blocks

Every anesthetist should have the expertise to perform lumbar puncture that is the prerequisite to induce spinal anesthesia. Spinal anesthesia is easy and effective technique: small amount of local anesthetic injected in the lumbar cerebrospinal fluid provides highly effective anesthesia, analgesia, and sympathetic and motor block in the lower part of the body. The main limitation of spinal anesthesia is a variable and relatively short duration of the block with a single-injection of local anesthetic. With appropriate use of adjuvant or combining spinal anesthesia with epidural anesthesia, the analgesic action can be controlled in case of early recovery of initial block or in patients with prolonged procedures. Contraindications are rare. Bleeding disorders and any major dysfunction in coagulation system are rare in children, but spinal anesthesia should not be used in children with local infection or increased intracranial pressure. Children with spinal anesthesia may develop the same adverse effects as has been reported in adults, but in contrast to adults, cardiovascular deterioration is uncommon in children even with high blocks. Most children having surgery with spinal anesthesia need sedation, and in these cases, close monitoring of sufficient respiratory function and protective airway reflexes is necessary. Postdural puncture headache and transient neurological symptoms have been reported also in pediatric patients, and thus, guardians should be provided instructions for follow-up and contact information if symptoms appear or persist after discharge. Epidural blood patch is effective treatment for prolonged, severe headache, and nonopioid analgesic is often sufficient for transient neurological symptoms.

Validation of a preclinical spinal safety model: effects of intrathecal morphine in the neonatal rat

BACKGROUND

Preclinical studies demonstrate increased neuroapoptosis after general anesthesia in early life. Neuraxial techniques may minimize potential risks, but there has been no systematic evaluation of spinal analgesic safety in developmental models. We aimed to validate a preclinical model for evaluating dose-dependent efficacy, spinal cord toxicity, and long-term function after intrathecal morphine in the neonatal rat.

METHODS

Lumbar intrathecal injections were performed in anesthetized rats aged postnatal day (P) 3, 10, and 21. The relationship between injectate volume and segmental spread was assessed postmortem and by in vivo imaging. To determine the antinociceptive dose, mechanical withdrawal thresholds were measured at baseline and 30 min after intrathecal morphine. To evaluate toxicity, doses up to the maximum tolerated were administered, and spinal cord histopathology, apoptosis, and glial response were evaluated 1 and 7 days after P3 or P21 injection. Sensory thresholds and gait analysis were evaluated at P35.

RESULTS

Intrathecal injection can be reliably performed at all postnatal ages and injectate volume influences segmental spread. Intrathecal morphine produced spinally mediated analgesia at all ages with lower dose requirements in younger pups. High-dose intrathecal morphine did not produce signs of spinal cord toxicity or alter long-term function.

CONCLUSIONS

The therapeutic ratio for intrathecal morphine (toxic dose/antinociceptive dose) was at least 300 at P3 and at least 20 at P21 (latter doses limited by side effects). These data provide relative efficacy and safety for comparison with other analgesic preparations and contribute supporting evidence for the validity of this preclinical neonatal safety model.

Tolerance and withdrawal from prolonged opioid use in critically ill children

OBJECTIVE

After prolonged opioid exposure, children develop opioid-induced hyperalgesia, tolerance, and withdrawal. Strategies for prevention and management should be based on the mechanisms of opioid tolerance and withdrawal.

PATIENTS AND METHODS

Relevant manuscripts published in the English language were searched in Medline by using search terms "opioid," "opiate," "sedation," "analgesia," "child," "infant-newborn," "tolerance," "dependency," "withdrawal," "analgesic," "receptor," and "individual opioid drugs." Clinical and preclinical studies were reviewed for data synthesis.

RESULTS

Mechanisms of opioid-induced hyperalgesia and tolerance suggest important drug- and patient-related risk factors that lead to tolerance and withdrawal. Opioid tolerance occurs earlier in the younger age groups, develops commonly during critical illness, and results more frequently from prolonged intravenous infusions of short-acting opioids. Treatment options include slowly tapering opioid doses, switching to longer-acting opioids, or specifically treating the symptoms of opioid withdrawal. Novel therapies may also include blocking the mechanisms of opioid tolerance, which would enhance the safety and effectiveness of opioid analgesia.

CONCLUSIONS

Opioid tolerance and withdrawal occur frequently in critically ill children. Novel insights into opioid receptor physiology and cellular biochemical changes will inform scientific approaches for the use of opioid analgesia and the prevention of opioid tolerance and withdrawal.

Population pharmacokinetics of remifentanil in infants and children undergoing cardiac surgery

Background

The aim of this study was to provide a model-based analysis of the pharmacokinetics of remifentanil in infants and children undergoing cardiac surgery with cardiopulmonary bypass (CPB).

Methods

We studied nine patients aged 0.5 to 4 years who received a continuous remifentanil infusion via a computer-controlled infusion pump during cardiac surgery with mildly hypothermic CPB were studied. Arterial blood samples taken prior to, during and after CPB were analyzed for remifentanil concentrations using a validated gas-chromatographic mass-spectrophotometric assay. We used population mixed-effects modeling to characterize remifentanil pharmacokinetics. The final model was evaluated by its predictive performance.

Results

The pharmacokinetics of remifentanil was described by a 1-compartment model with adjustments for CPB. Population mean parameter estimates were 1.41 L for volume of distribution (V) and 0.244 L/min for clearance. V was increased during CPB and post-CPB to 2.41 times the pre-CPB value. The median prediction error and the median of individual median absolute prediction error were 2.44% and 21.6%, respectively.

Conclusion

Remifentanil dosage adjustments are required during and after CPB due to marked changes in the V of the drug. Simulations indicate that a targeted blood concentration of 14 ng/mL is achieved and maintained in 50% of typical patients by administration of an initial dose of 18 μg remifentanil followed by an infusion of 3.7 μg/min before, during and post-CPB, supplemented with a bolus dose of 25 μg given at the start of CPB.

Opioid analgesia in neonates following cardiac surgery

Pain in the newborn is complex, involving a variety of receptors and mechanisms within the developing nervous system. When pain is generated, a series of sequential neurobiologic changes occur within the central nervous system. If pain is prolonged or repetitive, the developing nervous system could be permanently modified, with altered processing at spinal and supraspinal levels. In addition, pain is associated with a number of adverse physiologic responses that include alterations in circulatory (tachycardia, hypertension, vasoconstriction), metabolic (increased catabolism), immunologic (impaired immune response), and hemostatic (platelet activation) systems. This "stress response" associated with cardiac surgery in neonates could be profound and is associated with increased morbidity and mortality. Neonates undergoing cardiac operations are exposed to extensive tissue damage related to surgery and additional painful stimulation related to endotracheal and thoracostomy tubes that may remain in place for variable periods of time following surgery. In addition, postoperatively neonates endure repeated procedural pain from suctioning of endotracheal tubes, placement of vascular catheters, and manipulation of wounds (eg, sternal closure) and dressings. The treatment and/or prevention of pain are widely considered necessary for humanitarian and physiologic reasons. Improved clinical and developmental outcomes underscore the importance of providing adequate analgesia for newborns who undergo major surgery, mechanical ventilation, and related procedures in the intensive care unit. This article reviews published information regarding opioid administration and associated issues of tolerance and abstinence syndromes (withdrawal) in neonates with an emphasis on those having undergone cardiac surgery.

Anesthesia and postoperative analgesia in pediatric patients undergoing cardiac surgery

Pediatric cardiac anesthesiologists care for patients ranging from premature infants weighing <2 kg to adults requiring surgical intervention for congenital heart disease. Along with their cardiac pathophysiologies, many of these patients also have other co-existing diseases that can affect their anesthetic management. Recent advances in monitoring include non-invasive neuromonitors, such as near-infrared spectroscopy and trans-cranial Doppler, which are assuming increasing importance in intraoperative management, particularly during cardiopulmonary bypass. A variety of anesthetic techniques, including regional anesthesia, can be used to facilitate early extubation in older infants and children with stable postoperative hemodynamics. In addition to regional anesthesia, other modalities for the management of postoperative pain include opioid infusions in critically ill children and the use of patient- or nurse-controlled analgesia pumps. Multiple pain assessment tools are available for children of varying ages and developmental levels to assist in providing appropriate postoperative pain management.

Endogenous opiates and behavior: 2005

This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).