Page 37 - Delaware Medical Journal - July/August 2020

TREATMENT
Table 1: Opioid and ketamine taper schedule and WAT-1 scores
DAY
OXYCODONE
KETAMINE
WAT-1
1
5 mg oxycodone every 4 hours (30 MME/day)
0.20 mg/kg/hr
0
2
5 mg oxycodone every 6 hours (20 MME/day)
0.25 mg/kg/hr
0
3
5 mg oxycodone every 8 hours (15 MME/day)
0.35 mg/kg/hr
0
4
5 mg oxycodone every 12 hours (10 MME/day)
0.35 mg/kg/hr
0
5
5 mg oxycodone every 24 hours (5 MME/day)
0.35 0.175 mg/kg/hr
0
6
None
None
0
was made to offer a ketamine-assisted, rapid opioid wean in the pediatric intensive care unit (PICU). The patient agreed to
the recommended plan and expressed hopefulness that the ketamine infusion would help to reduce both her pain and her increasing reliance on opioid medications.
The ketamine dosing protocol utilized in
this study was designed based on previously published reports.1–3 Ketamine was started
at 0.1mg/kg/hr and titrated up to 0.35mg/kg/ hr during the opioid wean which started at
30 milligram morphine equivalents (MME)/ day to match her outpatient dosage (Table
1 & Figure 1). She was also started on a multimodal analgesic regimen consisting of gabapentin, hydroxyzine, acetaminophen, ibuprofen, and distraction techniques in the form of physical/massage/art/music therapy. Lorazepam was used to minimize ketamine side effects. Her main side effect was visual hallucination of “bubbles.” Her Withdrawal Assessment Tool (WAT-1) scores remained at 0 throughout the taper. Refer to Table 2
for WAT-1 scoring. Following the wean,
she was transferred out of the PICU, where she was stable off opioids without vital sign abnormalities. However, she continued to report intractable pain and endorsed active suicidal ideation. Her sickle cell percentage was 30.8%, indicating her pain was likely unrelated to acute VOC, as our patient reported. Imaging did not suggest avascular necrosis as a source of her pain either. It
was suspected that a major component of
her pain was neuropsychiatric, and in the setting of her active suicidal ideation, she was transferred to a medical psychiatric unit for continued management.
DISCUSSION
Sickle cell disease (SCD) is a hereditary hemoglobinopathy caused by a single base pair alteration from the wild-type B-globin gene. This change promotes abnormal B-globin protein interactions in the deoxygenated state, which causes erythrocytes to become sickle-shaped.
These sickled cells are rigid, obstruct
narrow capillary vessels, and trigger
painful ischemic episodes also known as vaso-occlusive crises (VOC). Over time, recurrent episodes of VOC cause long-
term neurochemical changes that present clinically as chronic pain.5,6 Chronic pain from SCD has been reported to be worse than postoperative pain and equivalent to cancer pain and affects 29% of adults and 40% of pediatric SCD patients (ages 8-18 yrs).5,7 In 2017, the Analgesic, Anesthetic,
and Addiction Clinical Trial Translations Innovations Opportunities and Networks- American Pain Society Pain Taxonomy (AAPT) published evidence-based guidelines to diagnose chronic pain in SCD (Table
3).7 Based on these criteria, the patient presented has chronic pain. However, her history of frequent, escalating opioid use without pain relief over the past year and persistent, uncontrolled pain in the absence of VOC raises concern for opioid-induced hyperalgesia (OIH).
Pain management in SCD has relied heavily on opioid medications. However, long-term use of opioids should be avoided as there is a high risk for adverse effects such as OIH, tolerance, dependence, and addiction. In OIH, patients can develop increasing pain (hyperalgesia), extreme skin sensitivity, mental status changes, and even myoclonus. The quality and type of pain may resemble
Table 2: WAT-1 Scoring4
Previous 12 hours
Scoring
Any loose/watery stools
No = 0 Yes = 1
Any vomiting/retching/gagging
No = 0 Yes = 1
Temperature > 37.8°C
No = 0 Yes = 1
2-minute pre-stimulus observation
State Behavioral Scale (SBS)
≤ 0 or asleep/awake/calm = 0
1≥ or awake/distressed = 1
Tremor
None/mild = 0 Moderate/severe = 1
Sweating
No = 0 Yes = 1
Uncoordinated/repetitive movement
No = 0 Yes = 1
Yawning or sneezing
No = 0 Yes = 1
1-minute stimulus observation
Startle to touch
No = 0 Yes = 1
Muscle tone
Normal = 0 Increased = 1
Post-stimulus recovery
Time to gain calm state (SBS ≤ 0)
< 2 min = 0
2 – 5 min = 1
> 5 min = 2
Total Score
(0-12)
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