Analgesia and sedation after pediatric cardiac surgery

Transversus Thoracic Muscle Plane Block For Postoperative Pain in Pediatric Cardiac Surgery: A Systematic Review And Meta-Analysis of Randomized And Observational Studies

OBJECTIVES

Pediatric patients undergoing cardiac surgery usually experience significant surgical pain. Additionally, the effect of poor surgical analgesia creates a pain continuum that extends to the postoperative period. Transversus thoracic muscle plane block (TTMPB) is a novel plane block technique that can provide analgesia to the anterior chest wall. The analgesic role of TTMPB in pediatric cardiac surgery is still uncertain. A meta-analysis was conducted to determine the analgesic efficacy of this procedure.

DESIGN AND SETTING

Systematic review and meta-analysis. PubMed, Embase, Web of Science, CENTRAL, WanFang Data, and the China National Knowledge Infrastructure were searched to November 2023, and the Grading of Recommendations Assessment, Development, and Evaluation approach was followed to evaluate the certainty of evidence.

PARTICIPANTS

Eligible studies enrolled pediatric patients from 2 months to 12 years old scheduled to undergo cardiac surgery, and randomized them to receive a TTMPB or no block/sham block.

MEASUREMENTS AND MAIN RESULTS

Six studies that enrolled 601 pediatric patients were included. Low-certainty evidence from randomized trials showed that, compared with no block or sham block, TTMPB in pediatric patients undergoing cardiac surgery may reduce postoperative modified objective pain score at 12 hours (weighted mean difference [WMD] -2.20, 95% CI -2.73 to -1.68) and 24 hours (WMD -1.76, 95% CI -2.09 to -1.42), intraoperative opioid consumption (WMD -3.83, 95% CI -5.90 to -1.76 μg/kg), postoperative opioid consumption (WMD -2.51, 95% CI -2.84 to -2.18 μg/kg), length of intensive care unit (ICU) stay (WMD -5.56, 95% CI -8.30 to -2.83 hours), and extubation time (WMD -2.13, 95% CI -4.21 to -0.05 hours). Retrospective studies provided very low certainty that the results were consistent with the randomized trials.

CONCLUSION

Very low- to low-certainty evidence showed that TTMPB in pediatric patients undergoing cardiac surgery may reduce postoperative pain, opioid consumption, ICU length of stay, and extubation time.

Apoptotic mechanism of development inhibition in zebrafish induced by esketamine

Esketamine, a widely used intravenous general anesthetic, is also employed for obstetric and pediatric anesthesia, and depression treatment. However, concerns regarding esketamine abuse have emerged. Moreover, the potential in vivo toxicity of esketamine on growth and development remains unclear. To address these concerns, we investigated the effects of esketamine exposure on developmental parameters, cell apoptosis, and gene expression in zebrafish. Esketamine exposure concentration-dependently decreased the heart rate and body length of zebrafish embryos/larvae while increasing the hatching rate and spontaneous movement frequency. Developmental retardation of zebrafish larvae, including shallow pigmentation, small eyes, and delayed yolk sac absorption, was also observed following esketamine treatment. Esketamine exposure altered the expression of apoptosis-related genes in zebrafish heads, primarily downregulating bax, caspase9, caspase3, caspase6, and caspase7. Intriguingly, BTSA1, a Bax agonist, reversed the anti-apoptotic and decelerated body growth effects of esketamine in zebrafish. Collectively, our findings suggest that esketamine may hinder embryonic development by inhibiting embryonic apoptosis via the Bax/Caspase9/Caspase3 pathway. To the best of our knowledge, this is the first study to report the lethal toxicity of esketamine in zebrafish. We have elucidated the developmental toxic effects of esketamine on zebrafish larvae and its potential apoptotic mechanisms. Further studies are warranted to evaluate the safety of esketamine in animals and humans.

Enhanced recovery after surgery in congenital duodenal obstruction

BACKGROUND

The present study aims to explore the clinical application of enhanced recovery after surgery (ERAS) in pediatric patients with congenital upper gastrointestinal obstruction (CUGIO).

METHODS

A total of 82 pediatric patients with CUGIO admitted to the neonatal intensive care unit in Kunming Children's Hospital between June 2017 and June 2021 were enrolled in the present study and divided into two groups: the ERAS group (n = 46) and the control group (n = 36). The ERAS management mode was adopted in the ERAS group, and the conventional perioperative management mode was adopted in the control group.

RESULTS

In the ERAS group and the control group, the time to the first postoperative bowel movement was 49.2 ± 16.6 h and 58.4 ± 18.8 h, respectively, and the time to the first postoperative feeding was 79 ± 7.1 h and 125.2 ± 8.3 h, respectively. The differences in the above two indicators between the two groups were statistically significant (P < 0.05). In the ERAS group, the days of parenteral nutrition and the length of hospital stay were 14.5 ± 2.3 d and 18.8 ± 6.4 d, respectively. In the control group, 17.6 ± 2.2 d and 23.1 ± 8.1 d, respectively. The differences in these two indicators between the two groups were statistically significant (P < 0.05).

CONCLUSION

The ERAS management model had a positive effect on early postoperative recovery in pediatric patients with CUGIO.

Transversus thoracic muscle plane block for pain during cardiac surgery: a systematic review and meta-analysis

STUDY OBJECTIVE

The role of transversus thoracic muscle plane blocks (TTMPBs) during cardiac surgery is controversial. We conducted a systematic review to establish the effectiveness of this procedure.

DESIGN

Systematic review. We searched PubMed, Embase, Web of Science, CENTRAL, WanFang Data, and the China National Knowledge Infrastructure to June 2022, and followed the GRADE approach to evaluate the certainty of evidence.

STUDY ELIGIBILITY CRITERIA

Eligible studies enrolled adult patients scheduled to undergo cardiac surgery and randomized them to receive a TTMPB or no block/sham block.

MAIN RESULTS

Nine trials that enrolled 454 participants were included. Compared to no block/sham block, moderate certainty evidence found that TTMPB probably reduces postoperative pain at rest at 12 h [weighted mean difference (WMD) -1.51 cm on a 10 cm visual analogue scale for pain, 95% CI -2.02 to -1.00; risk difference (RD) for achieving mild pain or less (≤3 cm), 41%, 95% CI 17-65) and 24 h (WMD -1.07 cm, 95% CI -1.83 to -0.32; RD 26%, 95% CI 9-37). Moderate certainty evidence also supported that TTMPB probably reduces pain during movement at 12 h (WMD -3.42 cm, 95% CI -4.47 to -2.37; RD 46%, 95% CI 12-80) and at 24 h (WMD -1.73 cm, 95% CI -3.24 to -0.21; RD 32%, 95% CI 5-59), intraoperative opioid use [WMD -28 milligram morphine equivalent (MME), 95% CI -42 to -15], postoperative opioid consumption (WMD -17 MME, 95% CI -29 to -5), postoperative nausea and vomiting (absolute risk difference 255 less per 1000 persons, 95% CI 140-314), and intensive care unit (ICU) length of stay (WMD -13 h, 95% CI -21 to -6).

CONCLUSION

Moderate certainty evidence showed TTMPB during cardiac surgery probably reduces postoperative pain at rest and with movement, opioid consumption, ICU length of stay, and the incidence of nausea and vomiting.

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.

Continuous Incisional Lidocaine in Pediatric Patients following Open Heart Surgery

Continuous incisional lidocaine infusion has been proposed as an adjunctive therapy in the management of postoperative pain in adult patients. The aim of this study was to determine the efficacy and safety of a continuous subcutaneous lidocaine infusion in pediatric patients following open heart surgery. All patients receiving a subcutaneous lidocaine infusion in median sternotomy incisions after open heart surgery during 2 consecutive years were included in the study. A historical cohort of patients was used as a control group. Demographic variables (age, size, and surgical procedure), variables related to sedation and analgesia (COMFORT and analgesia scales, drug doses, and duration), and complications were registered. 106 patients in the lidocaine infusion group and 79 patients in the control group were included. Incisional analgesia was effective for the treatment of pain as it reduced the dose and duration of intravenous fentanyl (odds ratio (OR) 6.26, confidence interval (CI) 95%: 2.48-15.97, p = 0.001; OR 4.30, CI 95%: 2.09-8.84, p = 0.001, respectively). The reduction in fentanyl use was more important in children over two years of age. Adverse effects were seen in three children (2.8%): they all had decreased level of consciousness, and one of them presented seizures as well. Two of these three patients had lidocaine levels over 2 mcg/ml. A continuous lidocaine incisional infusion is effective for the treatment of pain after open heart surgery. This procedure reduced intravenous analgesic drug requirements in pediatric patients undergoing a median sternotomy incision. Although the incidence of secondary effects is low, monitoring of neurologic status and lidocaine blood levels are recommended in all patients.

Use of continuous infusion of clonidine for sedation in critically ill infants and children

BACKGROUND

Adequate sedation and analgesia are required for critically ill children in order to minimize discomfort, reduce anxiety, and facilitate care. This is commonly achieved through a combination of opioids and benzodiazepines. Prolonged use of these agents is associated with tolerance and withdrawal. Clonidine as an adjunctive sedative agent may reduce sedation-related adverse events.

OBJECTIVE

Our first aim was to describe the indication for clonidine administration and its secondary effects in a mixed cohort of critically ill children. Our secondary aim was to measure the consumption of sedatives during two study periods: before and after the use of clonidine in our pediatric intensive care unit (PICU).

METHODS

This was a single-center study conducted in a tertiary PICU and encompassed retrospective chart review of patients who received clonidine between November 2013 and April 2015. We collected data on clonidine dosage, duration of administration, indication for the prescription, and potential side effects. We analyzed the total consumption of sedatives over 18 months, before and after the introduction of clonidine in our sedation protocol.

RESULTS

A total of patients received clonidine, with a mean age of 2.2 ± 2.8 years. The primary reason for intensive care admission was respiratory failure (48%). The main indication for clonidine administration was increasing requirement for morphine and midazolam (60%). The mean duration of clonidine infusion was 9 ± 7.3 days. Bradycardia and hypotension occurred in five patients (11.6%) and nine patients (21%), respectively. These side effects did not result in any major intervention. Younger age was a risk factor for clonidine-associated bradycardia. We observed a significant decrease in morphine and midazolam consumption with clonidine as a comedication. Compared with the pre-study period, consumption decreased by 19.7% for morphine and by 59% for midazolam (calculated as milligram/admission).

CONCLUSION

Continuous infusion of clonidine in critically ill children is safe and effective. Clonidine is a sedative-sparing agent and this can help reduce complications associated with prolonged use of opioids and benzodiazepines.

Evaluation of the Analgesic Efficacy of Bilateral Ultrasound-Guided Transversus Thoracic Muscle Plane Block on Post-Sternotomy Pain: A Randomized Controlled Trial

PURPOSE

Transverse thoracic block is a new perioperative analgesic method for post-sternotomy discomfort. This study discusses the efficacy of an ultrasound-guided transversus thoracic muscle plane block (TTPB) in patients undergoing heart surgery, including sternotomy.

PATIENTS AND METHODS

In this prospective trial, 60 patients were randomly assigned to two groups: transversus (T) or general anesthesia (GA). Patients in the T group received TTPB with GA and 15 mL of 0.25% bupivacaine was administered on either side. Patients in the GA group received TTPB along with GA, but 15 mL saline was injected on either side instead. The patients were followed up postoperatively. The percentage of patients receiving additional opioids, extubation time, intensive care unit (ICU) length, postoperative morphine dose, and adverse events were documented.

RESULTS

The percentage of patients requiring additional morphine was significantly lower in the T group (p<0.015). Pain scores were comparable between the groups at extubation time and 18 h postoperatively. At 8, 12, and 24 h after surgery, pain scores in the T group were significantly lower (P<0.001). The total amount of morphine required after surgery was much lower in the T group (8±0.74 mg), and the duration to initial analgesic necessity was significantly greater in the GA group (P<0.001). Patients in the GA group had a considerably longer ventilation time (11.07±0.64) (P<0.001). The ICU stay in the T group was substantially shorter (P<0.001), and postoperative complications were comparable.

CONCLUSION

For patients undergoing heart surgery, TTPB offers sufficient postoperative pain control, resulting in lower pain scores, lower postoperative analgesic doses, shorter extubation times, and shorter ICU stay lengths.

Perioperative Opioid Consumption is Not Reduced in Cyanotic Patients Presenting for the Fontan Procedure

Adequate pain control is a critical component of the perioperative approach to children undergoing repair of congenital heart disease (CHD). The impact of specific anatomic and physiologic disturbances on the management of analgesia has been largely unexplored at the present time. Studies in other pediatric populations have found an association between chronic hypoxemia and an increased sensitivity to the effects of opioid medications. The purpose of this retrospective study was to examine perioperative opioid administration and opioid-associated adverse effects in children undergoing surgical repair of CHD, with a comparison between patients with and without chronic preoperative cyanosis. Patients between the ages of 2 and 5 years whose tracheas were extubated in the operating room were included and were classified in the cyanotic group if they presented for the Fontan completion. The primary outcomes of interest were intraoperative and postoperative opioid administration. Secondary outcomes included pain scores and opioid-related side effects. The study cohort included 156 patients. Seventy-one underwent the Fontan procedure, twelve of which were fenestrated. Fontan patients received fewer opioids intraoperatively (11.33 µg/kg fentanyl equivalents versus 12.56 µg/kg, p = 0.03). However, there were no differences with regards to opioid consumption postoperatively and no correlation between preoperative oxygen saturation and total opioid administration. There were no differences between groups with regards to the respiratory rate nadir, postoperative pain scores, or the incidence of opioid-related side effects. In contrast to other populations with chronic hypoxemia exposure, children with cyanotic CHD did not appear to have increased sensitivity to the effects of opioid medications.

Cardiac critical care of the post-operative congenital heart disease patient

Cardiac critical care has become an increasingly complex subspecialty, involving multiple subspecialists to support patients with congenital heart disease. This requires understanding of their physiology and the impact of medical interventions. The purpose of this article is to provide a concise review of the current strategies utilized by cardiac intensivists to optimize outcomes for this vulnerable patient population, with the goal of broadening the knowledge of other members of the multi-disciplinary team.

Effects of Midazolam on the Development of Adult Leydig Cells From Stem Cells In Vitro

BACKGROUND

Midazolam is a neurological drug with diverse functions, including sedation, hypnosis, decreased anxiety, anterograde amnesia, brain-mediated muscle relaxation, and anticonvulsant activity. Since it is frequently used in children and adolescents for extended periods of time, there is a risk that it may affect their pubertal development. Here, we report a potential effect of the drug on the development of Leydig cells (LCs), the testosterone (T)-producing cells in the testis.

METHODS

Stem LCs (SLCs), isolated from adult rat testes by a magnetic-activated cell sorting technique, were induced to differentiate into LCs in vitro for 3 weeks. Midazolam (0.1-30 μM) was added to the culture medium, and the effects on LC development were assayed.

RESULTS

Midazolam has dose-dependent effects on SLC differentiation. At low concentrations (0.1-5 μM), the drug can mildly increase SLC differentiation (increased T production), while at higher concentrations (15-30 μM), it inhibits LC development (decreased T production). T increases at lower levels may be due to upregulations of scavenger receptor class b Member 1 (SCARB1) and cytochrome P450 17A1 (CYP17A1), while T reductions at higher levels of midazolam could be due to changes in multiple steroidogenic proteins. The uneven changes in steroidogenic pathway proteins, especially reductions in CYP17A1 at high midazolam levels, also result in an accumulation of progesterone. In addition to changes in T, increases in progesterone could have additional impacts on male reproduction. The loss in steroidogenic proteins at high midazolam levels may be mediated in part by the inactivation of protein kinase B/cAMP response element-binding protein (AKT/CREB) signaling pathway.

CONCLUSION

Midazolam has the potential to affect adult Leydig cell (ALC) development at concentrations comparable with the blood serum levels in human patients. Further studies are needed to test the effects on human cells.

Transversus Thoracic Muscle Plane Block for Analgesia After Pediatric Cardiac Surgery

OBJECTIVE

The objective of this study was to assess the effectiveness of transversus thoracic muscle plane block (TTPB) as a novel technique for postoperative analgesia in pediatric cardiac surgery.

DESIGN

A retrospective study.

SETTING

A tertiary care teaching hospital.

PARTICIPANTS

Children who underwent congenital heart surgery through median sternotomy between January 2018 and March 2019.

INTERVENTIONS

Bilateral ultrasound-guided TTPB was performed as a single-shot technique before the sternal incision. A total dose of bupivacaine 0.25% (0.5 ml/kg) was injected between the fourth and fifth ribs just lateral to the sternum. Patients who received TTPB were designated as the TTPB group, and the other group was named the non-TTPB group MEASUREMENTS AND MAIN RESULTS: Thirty-three patients underwent intraoperative bilateral TTPB before the sternal incision and 37 did not. The groups were comparable as for demographic and intraoperative clinical characteristics. Pain scores were significantly lower in the TTPB group compared with the non-TTPB group (p < 0.001). Intraoperatively, non-TTPB patients received significantly higher doses of fentanyl (p < 0.001). Moreover, the total fentanyl dose during a 24-hour period was also higher in the non-TTPB group (p < 0.001). The time to extubation was significantly lower in the TTPB group than in the non-TTPB group (p < 0.001).

CONCLUSIONS

TTPB appeared to be an effective technique for postoperative analgesia in pediatric patients undergoing cardiac surgery using a median sternotomy approach.

The impact of introducing nurse-led analgesia and sedation guidelines in ventilated infants following cardiac surgery

INTRODUCTION

Enhanced clinical outcomes in the Paediatric Intensive Care Unit following standardisation of analgesia and sedation practice are reported. Little is known about the impact of standardisation of analgesia and sedation practice including incorporation of a validated distress assessment instrument on infants post cardiac surgery, a subset of whom have Trisomy 21. This study investigated whether the parallel introduction of nurse-led analgesia and sedation guidelines including regular distress assessment would impact on morphine administered to infants post cardiac surgery, and whether any differences observed would be amplified within the Trisomy 21 population.

METHODOLOGY

A retrospective single centre before/after study design was used. Patients aged between 44 weeks postconceptual age and one year old who had open cardiothoracic surgery were included.

RESULTS

61 patients before and 64 patients after the intervention were included. After the intervention, a reduction in the amount of morphine administered was not evident, while greater use of adjuvant sedatives and analgesics was observed. Patients with Trisomy 21 had a shorter duration of mechanical ventilation after the change in practice.

CONCLUSION

The findings from this study affirm the importance of the nurses' role in managing prescribed analgesia and sedation supported by best available evidence. A continued education and awareness focus on analgesia and sedation management in the pursuit of best patient care is imperative.

Evaluation of an updated sedation protocol to reduce benzodiazepines in a pediatric intensive care unit

Aim: Midazolam like other benzodiazepines is supposed to be neurotoxic in small children and to represent a risk factor for the development of delirium. The aim of this study was to evaluate whether a modified analgesia and sedation protocol is feasible and effective to reduce the requirement of midazolam in neonates and young infants after cardiac surgery.Methods: Patients aged 6 months or younger who underwent surgery for congenital heart disease with cardiopulmonary bypass were enrolled and divided into a pre-modification group (January-December 2016) and after adjusting our sedation protocol into a post-modification group (January-December 2018). We assessed the doses of midazolam, morphine and clonidine as well as sedation scores according to our nurse-driven sedation protocol every 8 h until 120 h after cardiac surgery. During weaning from analgesia and sedation, children were monitored regarding withdrawal symptoms and pediatric delirium.Results: Sixty-five patients were included (33 patients in the pre-modification group, 32 patients in the post-modification group). The number of patients receiving midazolam and the cumulative dose of midazolam could be successfully reduced. The sedation scores were still within the desired target range for adequate sedation without any negative side effects.Conclusions: It is feasible and safe to reduce the use of midazolam in infants after cardiac surgery maintaining sedation goals based on a modified nurse-driven analgesia and sedation protocol.

Pressure support ventilation, sigh adjunct to pressure support ventilation, and neurally adjusted ventilatory assist in infants after cardiac surgery: A physiologic crossover randomized study

OBJECTIVES

We sought to compare gas exchange, respiratory mechanics, and asynchronies during pressure support ventilation (PSV), sigh adjunct to PSV (PSV SIGH), and neurally adjusted ventilatory assist (NAVA) in hypoxemic infants after cardiac surgery.

DESIGN

Prospective, single-center, crossover, randomized physiologic study.

SETTING

Tertiary-care pediatric intensive care unit.

PATIENTS

Fourteen hypoxemic infants (median age 11.5 days [8.7-74]).

INTERVENTIONS

The protocol begins with a 1 hour step of PSV, followed by two consecutive steps in PSV SIGH and NAVA in random order, with a washout period of 30 minutes (PSV) between them.

MAIN RESULTS

Three infants presented an irregular Eadi signal because of diaphragmatic paralysis and were excluded from analysis. For the remaining 11 infants, PaO₂ /FiO ₂ and oxygenation index improved in PSV SIGH compared with PSV (P < 0.05) but not in NAVA compared with PSV. PSV SIGH showed increased tidal volumes and lower respiratory rate than PSV (P < 0.05), as well as a significant improvement in compliance with respiratory system indexed to body weight when compared with both PSV and NAVA (P < 0.01). No changes in mean airway pressure was registered among steps. Inspiratory time resulted prolonged for both PSV SIGH and NAVA than PSV (P < 0.05). NAVA showed the higher coefficient of variability in respiratory parameters and a significative decrease in asynchrony index when compared with both PSV and PSV SIGH (P < 0.01).

CONCLUSIONS

The adjunct of one SIGH per minute to PSV improved oxygenation and lung mechanics while NAVA provided the best patient-ventilator synchrony in infants after cardiac surgery.

Efficacy and Safety of Fentanyl in Combination with Midazolam in Children on Mechanical Ventilation

BACKGROUND

To evaluate the efficacy and safety of fentanyl for sedation therapy in mechanically ventilated children.

METHODS

This was a double-blind, randomized controlled trial of mechanically ventilated patients between 2 months and 18 years of age. Patients were randomly divided into two groups; the control group with midazolam alone, and the combination group with both fentanyl and midazolam. The sedation level was evaluated using the Comfort Behavior Scale (CBS), and the infusion rates were adjusted according to the difference between the measured and the target CBS score.

RESULTS

Forty-four patients were recruited and randomly allocated, with 22 patients in both groups. The time ratio of cumulative hours with a difference in CBS score (measured CBS-target CBS) of ≥ 4 points (i.e., under-sedation) was lower in the combination group (median, 0.06; interquartile range [IQR], 0-0.2) than in the control group (median, 0.15; IQR, 0.04-0.29) (P < 0.001). The time ratio of cumulative hours with a difference in CBS score of ≥ 8 points (serious under-sedation) was also lower in the combination group (P < 0.001). The cumulative amount of midazolam used in the control group (0.11 mg/kg/hr; 0.07-0.14 mg/kg/hr) was greater than in the combination group (0.07 mg/kg/hr; 0.06-0.11 mg/kg/hr) (P < 0.001). Two cases of hypotension in each group were detected but coma and ileus, the major known adverse reactions to fentanyl, did not occur.

CONCLUSION

Fentanyl combined with midazolam is safe and more effective than midazolam alone for sedation therapy in mechanically ventilated children.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02172014.

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.

Pharmacokinetics of S-ketamine during prolonged sedation at the pediatric intensive care unit

BACKGROUND

S-ketamine is the S(+)-enantiomer of the racemic mixture ketamine, an anesthetic drug providing both sedation and analgesia. In clinical practice, significant interpatient variability in drug effect of S-ketamine is observed during long-term sedation.

AIMS

The aim of this study was to evaluate the pharmacokinetic variability of S-ketamine in children aged 0-18 years during long-term sedation. Twenty-five children (median age: 0.42 years, range: 0.02-12.5) received continuous intravenous administrations of 0.3-3.6 mg/kg/h S-ketamine for sedation during mechanical ventilation. Infusion rates were adjusted to the desired level of sedation and analgesia based on the COMFORT-B score and Visual Analog Scale. Blood samples were drawn once daily at random time-points, and at 1 and 4 hours after discontinuation of S-ketamine infusion. Time profiles of plasma concentrations of S-ketamine and active metabolite S-norketamine were analyzed using nonlinear mixed-effects modeling software. Clearance and volume of distribution were allometrically scaled using the ¾ power model.

RESULTS

A total of 86 blood samples were collected. A 2-compartment and 1-compartment model adequately described the PK of S-ketamine and S-norketamine, respectively. The typical parameter estimates for clearance and central and peripheral volumes of distribution were: CL_S-KETAMINE =112 L/h/70 kg, V1_S-KETAMINE =7.7 L/70 kg, V2_S-KETAMINE =545L/70 kg, Q_S-kETAMINE =196 L/h/70 kg, and CL_{S-NORKETAMINE} =53 L/h/70 kg. Interpatient variability of CL_S-KETAMINE and CL_{S-NORKETAMINE} was considerable with values of 40% and 104%, respectively, leading to marked variability in steady-state plasma concentrations.

CONCLUSION

Substantial interpatient variability in pharmacokinetics in children complicates the development of adequate dosage regimen for continuous sedation.

Population pharmacokinetics of intravenous clonidine for sedation during paediatric extracorporeal membrane oxygenation and continuous venovenous hemofiltration

AIMS

Clonidine is used for sedation in the paediatric intensive care unit. Extracorporeal membrane oxygenation (ECMO) provides temporary support if respiratory and cardiac function is threatened. ECMO influences the pharmacokinetics of drugs. Clonidine during paediatric ECMO cannot be effectively titrated as PK data are lacking. The aim of this study is to describe clonidine PK in a particular ECMO system and propose dosing guidelines for children on this particular ECMO circuit.

METHODS

All children below the age of 18 years who received clonidine during ECMO were eligible. The pharmacokinetic analysis was conducted by nonlinear mixed effect modelling, which enables to establish the separate influences of determinants on drug blood level and to provide individualized dosing.

RESULTS

Twenty-two patients, median age 1 month (IQR 6.4) and weight at inclusion 4 kg (IQR 3.1) were included of whom 90% in addition to ECMO received pre-emptive continuous venovenous hemofiltration to optimize fluid balance. The clonidine clearance rate was two-fold that measured in patients not on ECMO. Clearance increased steeply with postnatal age: at days 6, 8 and 10, respectively 30%, 50% and 70% of the adult clearance rate was reached. The use of diuretics was associated with a lower clearance. The volume of distribution increased by 55% during ECMO support.

CONCLUSION

Our findings suggest that a higher dose of clonidine may be needed during ECMO. The PK parameters on ECMO and the dosing guidelines proposed hold the potential to improve sedation practices on ECMO but need to be repeated with different ECMO systems.

An international survey of management of pain and sedation after paediatric cardiac surgery

OBJECTIVE

The mainstay of pain treatment after paediatric cardiac surgery is the use of opioids. Current guidelines for its optimal use are based on small, non-randomised clinical trials, and data on the pharmacokinetics (PK) and pharmacodynamics (PD) of opioids are lacking. This study aims at providing an overview of international hospital practices on the treatment of pain and sedation after paediatric cardiac surgery.

DESIGN

A multicentre survey study assessed the management of pain and sedation in children aged 0-18 years after cardiac surgery.

SETTING

Pediatric intensive care units (PICU)of 19 tertiary children's hospitals worldwide were invited to participate. The focus of the survey was on type and dose of analgesic and sedative drugs and the tools used for their pharmacodynamic assessment.

RESULTS

Fifteen hospitals (response rate 79%) filled out the survey. Morphine was the primary analgesic in most hospitals, and its doses for continuous infusion ranged from 10 to 60 mcg kg^-1 h^-1 in children aged 0-36 months. Benzodiazepines were the first choice for sedation, with midazolam used in all study hospitals. Eight hospitals (53%) reported routine use of sedatives with pain treatment. Overall, type and dosing of analgesic and sedative drugs differed substantially between hospitals. All participating hospitals used validated pain and sedation assessment tools.

CONCLUSION

There was a large variation in the type and dosing of drugs employed in the treatment of pain and sedation after paediatric cardiac surgery. As a consequence, there is a need to rationalise pain and sedation management for this vulnerable patient group.

Pharmacodynamics and Pharmacokinetics of Morphine After Cardiac Surgery in Children With and Without Down Syndrome

OBJECTIVE

To compare the pharmacodynamics and pharmacokinetics of IV morphine after cardiac surgery in two groups of children-those with and without Down syndrome.

DESIGN

Prospective, single-center observational trial.

SETTING

PICU in a university-affiliated pediatric teaching hospital.

PATIENTS

Twenty-one children with Down syndrome and 17 without, 3-36 months old, scheduled for cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

A loading dose of morphine (100 μg/kg) was administered after coming off bypass; thereafter, morphine infusion was commenced at 40 μg/kg/hr. During intensive care, nurses regularly assessed pain and discomfort with validated observational instruments (COMFORT-Behavior scale and Numeric Rating Scale-for pain). These scores guided analgesic and sedative treatment. Plasma samples were obtained for pharmacokinetic analysis.

MEASUREMENTS AND MAIN RESULTS

Median COMFORT-Behavior and Numeric Rating Scale scores were not statistically significantly different between the two groups. The median morphine infusion rate during the first 24 hours after surgery was 31.3 μg/kg/hr (interquartile range, 23.4-36.4) in the Down syndrome group versus 31.7 μg/kg/hr (interquartile range, 25.1-36.1) in the control group (p = 1.00). Population pharmacokinetic analysis revealed no statistically significant differences in any of the pharmacokinetic variables of morphine between the children with and without Down syndrome.

CONCLUSIONS

This prospective trial showed that there are no differences in pharmacokinetics or pharmacodynamics between children with and without Down syndrome if pain and distress management is titrated to effect based on outcomes of validated assessment instruments. We have no evidence to adjust morphine dosing after cardiac surgery in children with Down syndrome.

Sedation and Analgesia in Pediatric Cardiac Critical Care

OBJECTIVES

This review will focus on the pharmacokinetics (with an emphasis on the context-sensitive half-time), pharmacodynamics, and hemodynamic characteristics of the most commonly used sedative/hypnotic, analgesic, and IV anesthetics used in cardiac intensive care. In addition, the assessment of pain and agitation and withdrawal will be reviewed.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSIONS

Children in the cardiac ICU often require one or more components of general anesthesia: analgesia, amnesia (sedation and hypnosis), and muscle relaxation to facilitate mechanical ventilation, to manage postoperative pain, to perform necessary procedures, and to alleviate fear and anxiety. Furthermore, these same children are often vulnerable to hemodynamic instability due to unique underlying physiologic vulnerabilities. An assessment of hemodynamic goals, postoperative procedures to be performed, physiologic vulnerabilities, and the intended duration of mechanical ventilation should be made. Based on this assessment, the optimal selection of sedatives, analgesics, and if necessary, muscle relaxants can then be made.

A Comparative Analysis of Preemptive Versus Targeted Sedation on Cardiovascular Stability After High-Risk Cardiac Surgery in Infants

OBJECTIVE

To compare the effect of two sedation practices on cardiovascular stability during the early postoperative period in young infants following cardiac surgery: the routine early use of midazolam infusion (preemptive sedation) and the discretionary use of sedatives tailored to the patient's clinical condition (targeted sedation).

DESIGN

Retrospective cohort study with matched controls.

SETTING

A 15-bedded pediatric cardiac ICU.

PATIENTS

Sedation strategies were compared by matching patients before and after the introduction of a targeted sedation guideline, replacing the existing practice of preemptive sedation. Inclusion criteria were age less than 6 months and cardiopulmonary bypass time greater than 150 minutes. Matching criteria were surgical procedure, age, and duration of cardiopulmonary bypass and cross-clamp. The main outcome was cardiovascular instability, defined by the presence of one of the following criteria in the first 12 hours after PICU admission: 1) simultaneous administration of greater than or equal to two inotropic or vasopressor drugs; 2) administration of greater than 60 mL/kg fluid boluses. Secondary outcomes were: 1) markers of cardiac output adequacy (heart rate, blood pressure, vasoactive inotropic score, urine output, volume of fluid boluses, central venous oxygen saturation, lactate); 2) occurrence of adverse events (cardiac arrest, extracorporeal membrane oxygenation, death); 3) sedatives administered and depth of sedation.

INTERVENTIONS

Introduction of a guideline of targeted sedation.

MEASUREMENTS AND MAIN RESULTS

Thirty-three patients with preemptive sedation were matched to 33 patients with targeted sedation. Targeted sedation resulted in less frequent oversedation, without compromising cardiovascular stability, as indicated by similar occurrence of cardiovascular instability (68.8% with preemptive sedation vs 62.5% with targeted sedation; p = 0.53) and adverse events, and similar markers of cardiac output adequacy. Although all preemptively sedated patients received an infusion of midazolam in the first 12 hours after surgery, only 19.4% of patients in the targeted sedation group received a sedative infusion (p < 0.001).

CONCLUSIONS

Our data suggest that after high-risk cardiac surgery in young infants, routine sedation with midazolam may not prevent low cardiac output syndrome. When accompanied by a careful assessment of level of sedation, routine sedation of infants after high-risk cardiac surgery can be avoided without compromising hemodynamic stability or patient safety. The potential benefit of this approach is reduced exposure to sedative.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care: Sedation, Analgesia and Muscle Relaxant

OBJECTIVE

This article reviews pharmacotherapies currently available to manage sedation, analgesia, and neuromuscular blockade for pediatric cardiac critical patients.

DATA SOURCES

The knowledge base of an expert panel of pharmacists, cardiac anesthesiologists, and a cardiac critical care physician involved in the care of pediatric cardiac critical patients was combined with a comprehensive search of the medical literature to generate the data source.

STUDY SELECTION

The panel examined all studies relevant to management of sedation, analgesia, and neuromuscular blockade in pediatric cardiac critical patients.

DATA EXTRACTION

Each member of the panel was assigned a specific subset of the studies relevant to their particular area of expertise (pharmacokinetics, pharmacodynamics, and clinical care) to review and analyze.

DATA SYNTHESIS

The panel members each crafted a comprehensive summary of the literature relevant to their area of expertise. The panel, as a whole, then collaborated to cohesively summarize all the available, relevant literature.

CONCLUSIONS

In the cardiac ICU, management of the cardiac patient requires an individualized sedative and analgesic strategy that maintains hemodynamic stability. Multiple pharmacological therapies exist to achieve these goals and should be selected based on the patient's underlying physiology, hemodynamic vulnerabilities, desired level of sedation and analgesia, and the projected short- or long-term recovery trajectory.

Prospective multicentre randomised, double-blind, equivalence study comparing clonidine and midazolam as intravenous sedative agents in critically ill children: the SLEEPS (Safety profiLe, Efficacy and Equivalence in Paediatric intensive care Sedation) study

BACKGROUND

Children in paediatric intensive care units (PICUs) require analgesia and sedation but both undersedation and oversedation can be harmful.

OBJECTIVE

Evaluation of intravenous (i.v.) clonidine as an alternative to i.v. midazolam.

DESIGN

Multicentre, double-blind, randomised equivalence trial.

SETTING

Ten UK PICUs.

PARTICIPANTS

Children (30 days to 15 years inclusive) weighing ≤ 50 kg, expected to require ventilation on PICU for > 12 hours.

INTERVENTIONS

Clonidine (3 µg/kg loading then 0-3 µg/kg/hour) versus midazolam (200 µg/kg loading then 0-200 µg/kg/hour). Maintenance infusion rates adjusted according to behavioural assessment (COMFORT score). Both groups also received morphine.

MAIN OUTCOME MEASURES

Primary end point Adequate sedation defined by COMFORT score of 17-26 for ≥ 80% of the time with a ± 0.15 margin of equivalence. Secondary end points Percentage of time spent adequately sedated, increase in sedation/analgesia, recovery after sedation, side effects and safety data.

RESULTS

The study planned to recruit 1000 children. In total, 129 children were randomised, of whom 120 (93%) contributed data for the primary outcome. The proportion of children who were adequately sedated for ≥ 80% of the time was 21 of 61 (34.4%) - clonidine, and 18 of 59 (30.5%) - midazolam. The difference in proportions for clonidine-midazolam was 0.04 [95% confidence interval (CI) -0.13 to 0.21], and, with the 95% CI including values outside the range of equivalence (-0.15 to 0.15), equivalence was not demonstrated; however, the study was underpowered. Non-inferiority of clonidine to midazolam was established, with the only values outside the equivalence range favouring clonidine. Times to reach maximum sedation and analgesia were comparable hazard ratios: 0.99 (95% CI 0.53 to 1.82) and 1.18 (95% CI 0.49 to 2.86), respectively. Percentage time spent adequately sedated was similar [medians clonidine 73.8% vs. midazolam 72.8%: difference in medians 0.66 (95% CI -5.25 to 7.24)]. Treatment failure was 12 of 64 (18.8%) on clonidine and 7 of 61 (11.5%) on midazolam [risk ratio (RR) 1.63, 95% CI 0.69 to 3.88]. Proportions with withdrawal symptoms [28/60 (46.7%) vs. 30/58 (52.6%)] were similar (RR 0.89, 95% CI 0.62 to 1.28), but a greater proportion required clinical intervention in those receiving midazolam [11/60 (18.3%) vs. 16/58 (27.6%) (RR 0.66, 95% CI 0.34 to 1.31)]. Post treatment, one child on clonidine experienced mild rebound hypertension, not requiring intervention. A higher incidence of inotropic support during the first 12 hours was required for those on clonidine [clonidine 5/45 (11.1%) vs. midazolam 3/52 (5.8%)] (RR 1.93 95% CI 0.49 to 7.61).

CONCLUSIONS

Clonidine is an alternative to midazolam. Our trial-based economic evaluation suggests that clonidine is likely to be a cost-effective sedative agent in the PICU in comparison with midazolam (probability of cost-effectiveness exceeds 50%). Rebound hypertension did not appear to be a significant problem with clonidine but, owing to its effects on heart rate, specific cardiovascular attention needs to be taken during the loading and early infusion phase. Neither drug in combination with morphine provided ideal sedation, suggesting that in unparalysed patients a third background agent is necessary. The disappointing recruitment rates reflect a reluctance of parents to provide consent when established on a sedation regimen, and reluctance of clinicians to allow sedation to be studied in unstable critically ill children. Future studies will require less exacting protocols allowing enhanced recruitment.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN02639863.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 71. See the NIHR Journals Library website for further project information.

Endocrinopathies in the cardiac ICU

The past several years have seen an increased appreciation of the potential role of the endocrine system in the recovery process following surgery for congenital heart disease. Many of the hormonal changes following cardiac surgery are adaptive and necessary, whereas activation of proinflammatory cytokine and chemokine responses and some of the metabolic changes following surgery are likely mediators leading to detrimental outcomes. Additionally, other hormonal perturbations may contribute to adverse outcomes. This review examines the pain and the stress response, thyroid function and hyperglycemia following cardiopulmonary bypass (CPB), and the potential role of corticosteroids in the pediatric cardiac critical care unit.