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Cardiac Intensive Care

Opioid Weaning Protocol Using Morphine Compared With Nonprotocolized Methadone Associated With Decreased Dose and Duration of Opioid After Norwood Procedure

Achuff, Barbara-Jo MD, FAAP1; Lemming, Katherine PharmD2; Causey, Jamie C. MD1; Sembera, Kerry A. RN3; Checchia, Paul A. MD, FAAP, FAAC1; Heinle, Jeffrey S. MD4; Ghanayem, Nancy S. MD5

Author Information
Pediatric Critical Care Medicine: May 2022 - Volume 23 - Issue 5 - p 361-370
doi: 10.1097/PCC.0000000000002885

Abstract

RESEARCH IN CONTEXT

  • Opioids used for recovery after surgery or medical disease in the ICU come with a risk of tolerance and withdrawal syndrome. Weaning opioids in PICU has great variability and can lead to high opioid dose exposure.
  • High dose and duration of opioids may be detrimental to neonatal neurologic development especially vulnerable patients after Norwood palliation.
  • We hypothesize that standardized weaning protocol with a short acting agent could be associated with decreased opioid dosing and duration and secondarily decreased length of hospitalization in this population.

Opioids are used to manage pain, offer comfort, maintain the safety of medical devices, and decrease oxygen consumption for recovery particularly in populations at high risk for circulatory collapse. Additionally, adequate analgesia/sedation can help reduce stress and improve outcomes (1,2). Many studies have reported complications and prolonged hospitalization associated with high opioid dose and long duration of opioid exposure including, but not limited to, opioid tolerance, iatrogenic withdrawal syndrome (IAWS), and exacerbation of delirium after critical illness (3–7). Importantly, there is increasing evidence that long-term exposure to narcotics including opioids may be harmful to the neurologic outcomes of pediatric patients and can be more concerning in this population (8–12). Patients undergoing Norwood palliation (NP) in the immediate newborn period are at risk for long-term opioid infusions and sedation leading to prolonged weaning from opioids and longer hospitalization and may be a particularly vulnerable population.

Weaning opioid medications while avoiding withdrawal symptoms represents an area in which well-orchestrated strategies may lead to a positive impact. Opioid withdrawal can be treated or prevented by using a variety of therapeutic approaches (13). Using a risk-stratified opioid weaning protocol decreased opioid exposure and length of stay (LOS) for older PICU patients (14). A younger cardiac ICU (CICU) population was also described to experience a reduction in opioid exposure, duration, symptoms of withdrawal, and a decrease in hospital LOS with the use of a standardized weaning protocol (15). A recent systematic review reported that wide heterogeneity in the interventions used for weaning opioids in pediatric critical care led to the failure of any conclusion on early outcomes, and a recent meta-analysis did not identify sufficient evidence to recommend any strategy or medication over others when weaning opioids (16,17). Studies suggest that shorter acting agents may offer an advantage as those treated with morphine (MOR) in the newborn period compared to those treated with methadone (MTD) had significantly higher scores in cognitive and gross motor domains when tested as older children (18). The primary aim of this study is to report that a standardized protocol using shorter acting MOR compared with MTD is associated with a shorter duration and less total opioid dose exposure. As a secondary objective, we explore the association with shortened length of hospitalization in patients weaned with MOR versus MTD after NP.

MATERIALS AND METHODS

We report a study for pre- and postimplementations of a standardized opioid weaning protocol using historical controls in the pediatric CICU at Texas Children’s Hospital from January 1, 2017, to December 1, 2018. This single institutional study was approved by Baylor College of Medicine Institutional Review Board protocol number H-37037, and consent was waived for data collection and analysis. The Guidelines for Enhancing the QUAlity and Transparency Of health Research (EQUATOR) network guidelines were followed utilizing the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: guidelines for reporting observational studies (http://www.equator-network.org).

The study was inclusive of all patients undergoing NP from January 1, 2017, to December 1, 2018. There was no major change in surgical, anesthesia, cardiology, or critical care faculty, nor was there any major practice changes during this time. Patients that died before the completion of their wean from opioid medications were excluded. All clinical and outcomes data were extracted digitally from the electronic health record (EPIC, Verona, WI) as well as a locally developed quality improvement clinical database utilizing the local Society of Thoracic Surgery (STS) and Pediatric Cardiac Critical Care registry data descriptors. Demographics including age, weight, gender, prematurity, the presence of preoperative factors (mechanical ventilatory or circulatory support, shock, arrhythmia, and neurologic deficit as defined in the STS database) (19), shunt type, and delayed sternal closure (DSC) were evaluated. Patients were categorized as having a complicated postoperative course defined as the patient experiencing at least one of the diagnoses outlined in Table 1. By separating this cohort of complicated patients, it allowed subanalysis and more direct comparison for those patients with additional diagnoses or treatments that may have required higher opioid doses or longer lengths of ventilation and hospitalization. The cohort was divided into the historic control nonprotocolized MTD group, and the group weaned with protocolized MOR.

TABLE 1. - Definition of Norwood Procedure Complicated Course Survivors
n = 35
Postoperative Complication n Postoperative Complication n
Extracorporeal membrane oxygenation 3 Renal failure requiring renal replacement therapy 0
Cardiopulmonary resuscitation 1 Necrotizing enterocolitis 6
Bell II or III criteria
Cardiac reintervention 10 Neurologic 2
Surgical or catheterization Seizures or stroke
Arrhythmia 0 Prolonged ventilation 20
Listing for heart transplant 0 Hospital acquired conditions/infections 5
Cardiac reintervention excludes delayed sternal closure or reoperation for bleeding. Arrhythmia defined as that requiring permanent pacemaker. Seizures include clinical or subclinical. Stroke includes those with positive imaging (CT scan or MRI). Prolonged ventilation defined as greater than 7 d after sternal closure.

Standardized Postoperative Pain and Sedation

In 2017, before any opioid weaning strategy was introduced, all NP patients’ pain and sedation needs were managed similarly. The initiation and maintenance of opioid medications pre- or postoperatively were supported with the adoption of standardized weight and age-based analgosedation protocol for mechanically ventilated patients (Figure, Supplemental Digital Content 1, https://links.lww.com/PCC/B939, which depicts the institutional Sedation Initiation and Maintenance Protocol for Neonates). This neonatal-specific protocol recommends primarily single-agent fentanyl as needed for symptoms based on validated pain scores (age-specific) and sedation scores utilizing the State Behavioral Scale (20) with dexmedetomidine or benzodiazepine added as the second or third line agent as required. Opioid rotation was used when inadequate results were achieved. All postoperative patients were treated with IV acetaminophen for approximately 48–72 hours and then transitioned to the enteral formulation as required. No NP patients were treated with nonsteroidal anti-inflammatory drugs besides aspirin as per institutional shunt anticoagulation protocol.

Weaning Protocol Description

Before the implementation of a specific IAWS prevention protocol, the weaning of opioids was done at the discretion of the prescribing provider. The predominant nonprotocolized practice included the conversion of the opioid infusion to MTD injection periextubation, changed to enteral MTD when tolerated, and weaned typically every 3 days with MOR IV rescues for symptoms of withdrawal using the Withdrawal Assessment Tool (WAT-1) score (21). Starting in the last quarter of 2017, widespread educational programs were initiated including web-based learning and didactic lectures about analgesia and sedation weaning emphasizing the WAT-1. A novel weaning protocol developed by a multidisciplinary team using MOR was introduced and implemented in January 2018. The use of the protocolized wean with MOR specifically was not compulsory, and previous practice with MTD without protocol or the protocol with MOR was chosen at the discretion of the provider. There was overlap in practice during the study. The Figure and Conversion Table (Supplemental Digital Content 2, https://links.lww.com/PCC/B940) outlines the withdrawal prevention protocol that includes the stratification of risk for IAWS by the duration of opioid exposure in days (7,22). WAT-1 scores are documented by nursing starting on the first day of weaning and continued until 72 hours after the final dose. As needed, IV opioid doses are given for WAT-1 score greater than or equal to 4. Once specific dose thresholds are reached as defined by the protocol, the patient is converted to enteral dosing using a conversion table. No wean of opioids is recommended on days when WAT-1 scores are consistently high, greater than or equal to 4. In summary, infusions are weaned to oral conversion thresholds, the dose is converted to enteral followed by wean by 10–20% of original dose each day until defined basement dose is reached, and then the frequency of dosing decreased daily until off.

Primary outcomes of opioid dose and duration were electronically retrospectively counted including all opioid medications given intravenously or enterally of any opioid type via continuous infusion and intermittent scheduled or PRN pre- and postoperatively. Daily and total opioid doses were calculated as well as the “prewean” and the “wean phase” doses that are the total dose given preextubation and postextubation, respectively. The ratios to MOR equivalence were informed by text and literature (23); see Table, Supplemental Digital Content 3 (https://links.lww.com/PCC/B941) that depicts the conversion factors for opioids and benzodiazepines and references. Primary endpoints were daily, cumulative dose and wean phase dose in MOR milligram equivalents (MMEqs), length of opioid exposure prewean in days, and total duration (hours converted to days with division by 24). Calculations were done for the cohort of NP patients and the subset of complicated patients compared separately. To address possible confounding actions for sedation affecting the dosing of opioids for NP patients, adjuvant medications including benzodiazepines and dexmedetomidine were also counted and calculated by daily and total dose and reported for the total cohort and subset cohort in midazolam equivalents (MidazEq/kg) and micrograms (µg/kg). Outcomes were compared in NP patients preimplementation when weaning strategy was managed with nonprotocolized MTD and postimplementation that used protocolized MOR. Subset analysis of the cohort considered to have complications postoperatively that may have required higher and longer opioid doses was completed separately. The secondary outcome of length of hospitalization (admission date to discharge date in days) was analyzed for the total cohort and the subset cohort.

Statistical analyses were performed to assess demographics, clinical variables, and complications concerning the primary study outcome of the opioid dose and duration and the secondary outcome of LOS. Due to the absence of data regarding the prevalence of IAWS, a sample size calculation is difficult. The analysis was performed for the overall cohort as well as for the complicated subgroup. Missing data were excluded from the analysis, and the number of patients with data by a variable is indicated in the tables. Categorical and dichotomous variables were expressed as exact numbers with percentages, whereas continuous variables were expressed as median with 25th–75th interquartile ranges. Fisher exact and Pearson chi-square were used to identify associations between the categorical variables. Wilcoxon-Mann-Whitney U test was used to compare nonnormally distributed continuous variables. Statistical significance was defined as a p value of less than 0.05. Statistical analyses were carried out using JMP (Version 14, SAS, Cary, NC).

RESULTS

In the study period, 57 patients underwent NP, of whom three died (5%) before the completion of the opioid wean and were not included in the analysis. In the analyzed cohort, 27 patients were weaned with MTD and 27 patients were weaned using intermittent MOR. Of the survivors, 37 were discharged to home before second-stage palliation or bidirectional Glenn (BDG) operation and 17 remained hospitalized until the second stage operation or BDG. All patients were weaned from opioids before the second procedure. Table 2 reports the demographics and perioperative data for the total cohort. Birth characteristics, age at initial palliation, preoperative risk, shunt type, and intraoperative support times were not significantly different between the MTD and MOR groups. The historical MTD group was more likely to have DSC and more commonly had a complicated postoperative course (Table 2). DSC and complicated course are colinear variables, but not exclusive. Some noncomplicated patients had DSC, and not all complicated patients had DSC.

TABLE 2. - Demographics, Operative, and Perioperative Care
Variable Cohort (n = 54) Methadone Group (n = 27) Morphine Group (n = 27) p
Age (Med, d) 7 (4–12) 8 (4.5–24) 6 (4.5–8.5) 0.13
Gestational age (Med, wk) 39 (38–49) 39 (37.5–39) 39 (38–39) 0.49
Birth weight (Med, kg) 3.2 (2.9–3.7) 3.1 (2.8–3.8) 3.3 (2.9–3.6) 0.32
Male 34 (63%) 19 (56%) 15 (44%) 0.40
Prematurity (≤ 36 wk) 10 (19%) 6 (60%) 4 (40%) 0.73
High-risk category according to STAT definition high-risk category 25 (46%) 16 (64%) 9 (36%) 0.10
Cardiopulmonary bypass time (min) 199 (180–223) 201 (181–234) 196 (181–214) 0.20
Cross clamp time (min) 99 (87–117) 102 (90–123) 98 (88–110) 0.42
Circulatory arrest time (min) 10 (7–13) 10 (5–14) 9 (8–12) 0.61
Blalock-Taussig-Thomas shunt 25 (46%) 13 (52%) 12 (48%) 0.99
Sano-type shunt 29 (54%) 14 (48%) 15 (52%) 0.99
Delayed sternal closure 26 (48%) 20 (77%) 6 (23%) < 0.001
Complicated course 35 (65%) 23 (66%) 12 (34%) 0.004
Interstage discharge 34 (63%) 11 (33%) 23 (67%) 0.002
Med = median.

Analysis of the total cohort of patients reveals that along with the total daily and cumulative opioid doses for those weaned with MTD, the wean phase doses were significantly higher than the MOR group 115 versus 6 MMEq/kg (p < 0.001) (Table 3). The group with complicated course, 35 patients (65%), was analyzed as a separate subgroup. Although the prewean opioid doses were different between the MTD and protocolized MOR groups in the complicated subgroup (p = 0.03), there was no difference in the prewean dosing for the group with DSC (p = 0.46) and the uncomplicated group (p = 0.36) (Table 3). The complicated MTD group versus the complicated protocolized MOR group had higher daily dose exposure (3.3 vs 0.9 MMEq/kg/d; p < 0.001) and a higher wean phase dose (116 vs 7 MMEq/kg) along with a higher total cumulative dose (293 vs 41 MMEq/kg; p < 0.001) (Table 3; and Figure, Supplemental Digital Content 4, https://links.lww.com/PCC/B942, which displays a Box and whisker comparison of opioid dose between the groups). Patients with DSC that included both complicated and uncomplicated patients also had higher daily, wean dose and total opioid dose for their hospitalization. Additionally, our analysis failed to identify a difference between the uncomplicated and complicated subgroups in duration of opioids before weaning; 8 prewean days versus 5 for uncomplicated and 17 prewean days versus 9 for the complicated subgroup (p = 0.05 for both). However, there was a difference in the duration of weaning, 16 wean days versus 6 days for uncomplicated group and 56 wean days versus 12 for the complicated group with lengthening the total exposure for all groups weaned with nonprotocolized MTD and total exposure to opioids for the cohort (p < 0.001). A longer hospital LOS in the MTD group is seen compared with the protocolized MOR group within the complicated group but not for those without complications (Table 4; and Figure, Supplemental Digital Content 5, https://links.lww.com/PCC/B943, which displays a Box and whisker comparison of opioid duration between the groups). There were four patients (7%) sent home with a continued MTD wean. The analysis for total dose and duration ended at discharge, and it could be deduced to be yet longer since a home wean would have lengthened the duration of opioids for those patients.

TABLE 3. - Norwood Procedure Opioid Dose Morphine Milligram Equivalent/kg (Median [Interquartile Range])
Study Group n Daily Dose p Prewean Dose p Wean Dose p Total Dose p
All
 MTD 27 3 (0.9–9.6) < 0.001 52 (23–157) 0.04 115 (55–194) < 0.001 258 (87–397) < 0.001
 MOR 27 1.6 (0.3–4.2) 15 (8–35) 6 (4–13) 22 (14–55)
Delayed SC
 MTD 20 4.1 (1.36–11.8) < 0.001 104 (31–208) 0.46 116 (81–255) 0.01 286 (127–465) 0.02
 MOR 6 2.43 (0.7–8.1) 61 (34–108) 12 (7–12) 60 (41–113)
Uncomplicated
 MTD 4 0.8 (0.4–2.9) < 0.001 25 (20–28) 0.36 16 (13–20) 0.01 41 (39–46) 0.03
 MOR 15 1.6 (0.3–6.6) 13 (7–16) 5 (4–7) 19 (14–24)
Complicated
 MTD 23 3.3 (1.0–10.2) < 0.001 83 (28–190) 0.03 116 (86–194) < 0.001 293 (127–453) < 0.001
 MOR 12 0.9 (0.3–2.8) 32 (14–66) 7 (3–17) 41 (2–17)
MOR = morphine group, MTD = methadone.
Prewean dose is that dose before extubation. Wean dose is that dose after extubation and initiation of opioid wean.

TABLE 4. - Norwood Procedure Duration of Opioid Therapy and Length of Hospitalization in Days (Median [Iinterquartile Range])
Study Group n Prewean Days p Wean Days p Total Days p Length of Stay Days p
All
 MTD 27 14 (9–29) 0.003 45 (21–85) < 0.001 63 (35–107) < 0.001 131 (66–182) < 0.001
 MOR 27 7 (5–9) 7 (5–14) 12 (8–22) 42 (25–66)
Uncomplicated
 MTD 4 8 (7–10) 0.05 16 (15–17) 0.02 22 (20–24) 0.16 45 (41–55) 0.16
 MOR 15 5 (3–6) 6 (5–9) 10 (8–12.5) 32 (24–48)
Complicated
 MTD 23 17 (9–34) 0.05 56 (34–98) < 0.001 65 (47–112) < 0.001 150 (93–188) 0.01
 MOR 12 9 (7–13) 12 (5–15) 22 (8–28) 67 (41–109)
MOR = morphine group, MTD = methadone.
Does not include four patients sent home to continue MTD wean. Prewean days is before extubation. Wean days are the total days on opioid after wean commenced (duration of opioid in days).

Evaluating the adjuvant medications used for the total cohort first and then the complicated subset, all the MTD patients also received benzodiazepine during their hospitalization and had significantly higher doses than MOR patients (p < 0.001). Similarly, the MTD group received significantly more dexmedetomidine than the MOR group (p < 0.001) (Table 5). Additional subset analysis of the complicated patient subset for adjuvant medications revealed the MTD group had significantly higher benzodiazepine and dexmedetomidine dose exposure than the MOR patients.

TABLE 5. - Norwood Procedure Adjuvant Medication Dose
Study Group Benzodiazepine (Median [IQR]) Dexmedetomidine (Median [IQR])
n Midazolam Equivalents/kg p n µg/kg p
All
 MTD 27 28.6 (5.3–70.4) < 0.001 27 419 (252–739) < 0.001
 MOR 23 0.6 (0.3–2.1) 25 83 (33–122)
Uncomplicated
 MTD 4 3.9 (3–4.6) 0.01 4 117 (99–135) 0.06
 MOR 14 0.4 (0.3–0.7) 13 52 (30–89)
Complicated
 MTD 23 31.5 (13–81) 0.002 23 475 (347–783) 0.002
 MOR 9 2.4 (1–9) 12 116 (64–218)
IQR = interquartile range, MOR = morphine group, MTD = methadone.

DISCUSSION

Our analysis of patients who undergo NP revealed dramatic differences in opioid exposure when weaning with MTD versus protocolized MOR. The wean phase dose and duration were significantly higher for the MTD group. The cumulative dose of opioids was associated with a 12-fold higher dose for those weaned with MTD, and the duration of opioid exposure was five times longer when weaning with MTD instead of MOR. Inarguably, this could have an impact on short- and long-term outcomes for these patients.

Because of the complicated nature of single-ventricle palliation and the tenuous hemodynamics associated with parallel circulation, patients after NP are managed expectantly with meticulous attention to strict physiologic parameters that commonly result in prolonged sedation and analgesia. This high-level opioid exposure and resultant tolerance can have untoward effects with immediate risk for dependence, feeding intolerance with bowel dysfunction, and risky withdrawal symptoms. With good intentions, avoiding those potentially dangerous symptoms can subsequently lead to a long duration of opioid weaning and extended LOS. Patients with congenital heart disease especially those undergoing palliation for complex single-ventricle anatomy are at risk for poor neurodevelopmental outcomes at baseline, exacerbated by cardiopulmonary bypass along with lengthy and multiple exposures to narcotic medications (24,25).

Many would argue that lower opioid dose exposure in this population should originate with standardized sedation and analgesia protocols and not with weaning practices. Literature has reported the benefits of a standardized institutional protocol for “initiation” and maintenance of sedation and analgesia in decreasing total opioid exposure as our patients were managed; however, those protocols do not necessarily prevent tolerance and dependence (26). The absence of a standardized strategy potentially results in prolonged and higher exposure to opioids and/or withdrawal symptoms with studies reporting opioid wean durations ranging from days to weeks (27). Berens et al (28) randomized and compared two systematic opioid weaning protocols in critically ill and injured children at high risk for opioid withdrawal. Their study, using protocolized MTD, demonstrated that a weaning protocol of a shorter duration (5 vs 10 d) was safe and effective and has the potential to decrease ICU and total hospital days with minimal risk (28). Their findings specifically support the consideration of shorter opioid weaning schedules “by protocol” so that patients may be transitioned more rapidly from the critical care environment to a less intensively monitored setting. Additionally, Amirnovin et al (15) in the CICU setting have shown significant decreases in opioid dose and duration with the use of a risk-stratified standardized protocol utilizing hydromorphone for weaning without increase in withdrawal symptoms. The use of standardized protocol and not necessarily specific agents may appear to add to the strong association for decreased doses in our cohort. The noncompulsory choice of MOR versus MTD for weaning after the introduction of the protocol using MOR allowed overlap and the continued use of MTD in the environment of raised awareness and increased validated wean scoring. The comparison of those with complicated courses receiving MTD versus complicated patients with protocolized MOR for weaning still shows significant differences in dose exposure.

MTD is a synthetic opioid medication increasingly used in many areas of pediatric medicine because its N-methyl-d-aspartate receptor antagonism is advantageous in children suffering chronic pain. The very long pharmacologic actions offer a longer duration of analgesia than other common opioids, and its active enteral and IV bioavailability is useful in both neonates and children in intensive care suffering opioid withdrawal syndrome (29). When MTD is used as a weaning agent, the withdrawal syndrome can be delayed and prolonged (30,31). Additionally, the unpredictable, variable half-life of the enteral formulation also contributes to the added difficulty as a weaning agent compared with more consistent medications. Our reported results are reflective of the untoward effects of ultralong-acting MTD weaned very slowly over time. Using MOR in a standardized daily weaning process afforded by its short mechanism of action decreased both cumulative dose and duration of exposure.

The important separate analysis of NP patients who had complicated postoperative courses offered a better comparison of patients experiencing similar opioid needs and demonstrated an even greater difference in weaning strategies with a seven times higher cumulative opioid dose and three times longer opioid duration in the MTD group compared with those weaned with MOR. This subset of patients may be considered more at risk for withdrawal, and the provider’s choice of long-acting MTD after a complicated postoperative course would be reasonable. However, our results support that those patients also benefit from an MOR weaning plan versus MTD with significantly less dose and duration of opioid.

Wernovsky and Licht (32) have described that the LOS in the CICU, as well as hospitalization, can significantly increase morbidity and mortality. Along with the careful surgical palliation and the meticulous management of hemodynamics, the choices made for the initiation of sedatives and analgesia infusions and the subsequent weaning of those medications are imperative to determine the LOS. Importantly, when managed with MTD versus MOR, the associated LOS is 44% longer for NP patients managed with an MTD strategy compared with MOR and remains 33% longer when looking at only the subset with the complicated postoperative course. Although multifactorial, the choice of shorter acting opioids for weaning participated in the shortened LOS.

The influence of other sedatives on achieving reductions in opioid exposure is not clear in the literature, especially in postcardiac surgery pediatric patients. Most institutions, like ours, start with single-agent therapy for neonates and, however, use a strategy including multiple agents to reach satisfactory levels of analgesia and sedation. Intermittent benzodiazepines are routinely used in the management of sedation and patients with simultaneous prolonged exposure to continuous benzodiazepines, and opioids can also develop iatrogenic dependence and benzodiazepine-related withdrawal symptoms. Additionally, benzodiazepine and alpha-agonist may blunt the IAWS of opioid when used simultaneously. The subset analysis in this cohort shows that most of the NP patients received both benzodiazepines and dexmedetomidine in addition to opioid medications. In our results, those medications were not associated with a decrease in the total dose exposure of opioids for the MTD versus MOR cohorts as might be thought. The analysis reveals that receiving MTD is associated with more of both adjuvant therapies indicating a higher dose of all medications perhaps due to a slow wean of all agents dictated by the slower wean of long-acting MTD. Additionally, delirium adds challenges to the pain and sedation practice in the ICU with overlapping symptoms making the treatment of IAWS more difficult. We did not have a formally validated score for delirium in our CICU at the time of this study. The patients were thus treated similarly without a change in practice.

It should be noted that multidisciplinary educational efforts surrounding sedation and withdrawal scores along with the implementation of weaning strategies may have contributed to the decreased opioid dose and duration in the MOR group. Validated weaning scales were used for both MTD and MOR groups and were treated with rescue doses accordingly. Raising awareness to weaning opioids may have affected the number of rescue doses offered, and a defined standardized weaning strategy has importance in this population. It is difficult to measure the attitude and decision-making at the bedside; specifically, there are providers who by practice wean slower and tolerate fewer symptoms than others, which is not quantifiable. Limitations of the study are largely related to the nature of historical data analysis, which does not fully allow for control of factors unrelated to the protocol that may have additionally influenced outcomes. This is lessened by the fact that our study sample was homogeneous and over a period that did not include personnel, surgical, or medical practice changes in this cohort. Additionally, the historic MTD group is a noncontemporaneous population with noted periop differences in the use of DSC and complicated survival. It was thus important to include a subset analysis of those with added diagnoses and complicated course and report the conclusions of a higher cumulative opioid dose and duration for those treated with MTD even in that subset and that those complicated NP patients weaned with MOR had the benefit of less opioid dose and duration. Also, not measured are the socioeconomic difficulties with access to the enteral formulation of MTD that may have added to reasons for the LOS, also making MOR a better medication choice for weaning.

CONCLUSIONS

For patients undergoing NP, an opioid weaning protocol using MOR versus nonprotocolized MTD was associated with reduced exposure to opioids by 65% and reduced dose exposure by more than 10-fold, as well as a shortened LOS for those with complicated course.

AT THE BEDSIDE

  • Using short-acting morphine rather than long-acting methadone along with a standardized weaning protocol is associated with decreased opioid exposure.
  • This is true even for the patients with a complicated postoperative course.
  • ICU Clinicians should consider adopting protocolized opioid weaning with short-acting medications.

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Keywords:

adverse effects; congenital heart defect; methadone; morphinenewborn; opioid analgesics

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