Pharmacological Management of Postoperative Pain in Neonates Using Morphine

Pharmacological treatment for postoperative pain for a term neonate

The treatment of postoperative pain for this term infant after a jejunal atresia repair is a continuous dose of morphine through intravenous access, either a peripheral IV or a PICC line. The assumption is that this surgery was not done laparoscopically, and the surgeons made an abdominal incision while in the operating room. The dosing for this neonate will begin at 0.02 mg/kg/hour due to the hypotension that the patient had when he came back from OR (Taketomo, Hadding, & Kraus, 2019).

The drip will be titrated accordingly to maintain a therapeutic effect. PRN dosing is available with an indication of mild to moderate pain at 0.02 mg/kg/dose every hour if needed.

Appropriate dosing for acetaminophen

Acetaminophen will be used in conjunction with morphine for postoperative pain. The acetaminophen will be given intravenously as well. A set dose of 10 mg/kg every 6 hours will be given for 72 hours. A maximum dose of 40 mg/kg/day should not be exceeded due to the potential for hepatotoxicity (Taketomo, Hadding, & Kraus, 2019).

Therapeutic category and adverse effects of morphine and acetaminophen in the neonatal population

Morphine is considered an opioid analgesic. This drug can have significant adverse effects that the patient will be routinely monitored for post-operatively. A black box warning indicates that a chance of serious and life-threatening respiratory depression may occur. Hypotension is another significant adverse reaction that could affect this patient (Taketomo, Hadding, & Kraus, 2019).

Hypersensitivity is always a concern when starting a new medication. If hypersensitivity does occur, discontinuation of the drip is warranted, and additional pain management options should be explored. Morphine used for postoperative pain management in this patient may also cause decreased bowel motility, urinary retention, ureteral spasms, and oliguria (Taketomo, Hadding, & Kraus, 2019).

Acetaminophen has many adverse reactions as well. Two black box warnings for this drug pertain to the care of this neonate. The first black box warning enforces the need for correct dosing, ensuring that a dose in milligrams (mg) is not confused with milliliters (mL), that dosing of patients under 50 kilograms (kg) is based on weight, that infusion pumps are set correctly, and that the daily doses do not exceed the recommended daily maximum dose (Taketomo, Hadding, & Kraus, 2019).

The second black box warning explains that acetaminophen can be associated with acute liver failure. Hepatotoxicity is usually associated with excessive intake of the drug from multiple sources. Again, it is important not to exceed the maximum daily dosing of the medication from all sources that the patient is ordered (Taketomo, Hadding, & Kraus, 2019). Other adverse effects that the patient will be monitored for include hypotension and tachycardia, agitation, oliguria, atelectasis, and fever. Additionally, acetaminophen can cause electrolyte imbalances, including hypokalemia, hypomagnesemia, and hypophosphatemia (Taketomo, Hadding, & Kraus, 2019).

Mechanism of action for morphine and acetaminophen

Morphine binds to opioid receptors in the central nervous system. This causes the inhibition of ascending pain pathways, which alters the perception of and response to pain. It also produces generalized central nervous system depression (Taketomo, Hadding, & Kraus, 2019). The mechanism of action for acetaminophen is not completely understood. It is believed that the analgesic effects are caused by the activation of the descending serotonergic inhibitory pathways in the central nervous system.

There is some thought that there is some interaction with other nociceptive systems as well (Taketomo, Hadding, & Kraus, 2019). The hope is that the use of acetaminophen in conjunction with morphine will decrease the amount of opioid analgesic needed for effective pain management in this patient. Studies show that using acetaminophen as an adjunct to morphine improves overall pain scores and reduces the amount of time spent on opioids (Jelacic et al., 2016).

Monitoring effective pain management

Initially, vital signs are a great indicator of any pain that the sedated and paralyzed patient may feel. The patient’s heart rate and blood pressure will be high if there is a presence of pain. Unfortunately, the patient’s high heart rate and low blood pressure indicate that he may be hypovolemic. It is important that this is corrected before relying on these indicators for pain. After the paralytic and sedative wear off from surgery, the addition of a pain scale will be helpful in assessing any pain the patient may have.

The NPASS (Neonatal Pain/Agitation/Sedation scoring) is a pain scale that will be used to assess the pain and sedation level of the infant by looking at crying and irritability, behavior state, facial expressions, extremities tone, vital signs, and a premature pain assessment by rating each category from 0 to 2 (Hummel et al., 2008). If scoring higher than a 4, which is considered mild to moderate pain, a PRN dose of morphine may be indicated. Depending on how many morphine boluses are given in a twelve-hour period, an increase in the continuous drip dose may be needed to maintain a therapeutic effect.

Additional therapeutic considerations

There are significant considerations that need to be addressed for this patient. The most pressing and important one is that he is potentially hypovolemic. His high heart rate and low blood pressure are indicators that he may need a bolus of normal saline 10 mL/kg. It is important that this is corrected. Because of the infant’s current hypotension, the morphine drip was started at a lower dose. Hopefully, by doing this, any additional hypotension can be avoided. Antibiotics post-operatively would be ordered as well. This patient will receive Zosyn at 80 mg/kg/dose every 6 hours for seven days.

Zosyn has a broad-spectrum antimicrobial effect that covers gram-negative, gram-positive, and anaerobes. It is commonly used for intrabdominal infections (Taketomo, Hadding, & Kraus, 2019). A blood gas would be needed to check the appropriateness of the ventilator settings that the patient is currently on post-operatively. The patient would also be on servo mode under the radiant warmer to maintain normothermia. Hypothermic infants tend to experience more adverse events that require more supportive interventions during the postoperative period than normothermic infants (Hedwig S. et al., 2016).

Scope of Practice determinants for NNPs to prescribe

Largely, the state governments decide the scope of practice for any type of APRN. In Ohio specifically, the Ohio Revised Code (ORC) is a compilation of all the laws in Ohio that are written by the state legislature. The Ohio Administrative Code (OAC) is the rules and regulations that further break down and define those laws (OAAPN, 2018).

The Committee on Prescriptive Governance (CPG) updates the format of the prescriptive formulary and develops recommendations that pertain to the authority of prescribing certain drugs and therapeutic devices. The Ohio Board of Nursing (OBN) will adopt rules as necessary in order to implement provisions regarding the authority of clinical APNs to prescribe. These rules are consistent with the recommendations the OBN receives from the CPG (OAAPN, 2016).

Rules of prescriptive authority for NNPs in Ohio

According to the APRN Consensus Model from the NCSBN, neonatal nurse practitioners must have a written collaborative agreement and direct supervision by a licensed MD, DO, DDS, or podiatrist in order to prescribe (2020). This is known as a standard care arrangement (SCA). These agreements will outline the physician-practitioner relationship and must be reviewed and signed every two years and include off-label and schedule II prescribing authority (OAAPN, 2018).

In 2017, the need to obtain a certificate of authority (COA) and a certificate to prescribe (CTP) was removed, and the new APRN licensure was created. This allows for role designation between certified registered nurse anesthetists (CRNA), certified nurse-midwives (CNM), clinical nurse specialists (CNS), and certified nurse practitioners (CNP). As part of the new law, an exclusionary-only drug formulary was established to specify the drugs that APRNs are not authorized to prescribe (Cleveland Clinic, 2017).

Legal and Professional guidelines that affect the NNP role

The NNP must be aware of and educated on current literature and practices regarding the medications they prescribe, including safety alerts and recalls. It is also imperative that they stay up to date on all certifications and continuing education in order to legally prescribe and practice as an NNP. Certifications must be verified by the Ohio Board of Nursing. Currently, twelve hours of continuing education are needed every two years in regard to the pharmacology aspect of their practice (OAAPN, 2018).

A nurse practitioner should always prescribe within their correct scope of practice. The prescriber-patient relationship must be a valid one, and the nurse practitioner should obtain a history, conduct a physical exam, give a diagnosis, prescribe medications and rule out contraindications, consult with the collaborating physician, and document these steps in the medical record. Appropriate follow-up with these patients is necessary. OARRS reports should be run on every patient that receives a schedule II drug (OAAPN, 2018).

References

1. Cleveland Clinic (2017). APRNs in Ohio Now Licensed: New ‘APRN Modernization’ Bill
   became law in early April. https://consultqd.clevelandclinic.org/aprns-ohio-now-licensed/.
2. Hedwig, S. et al. (2016.) Time Trends and Predictors of Abnormal Postoperative Body
   The temperature in Infants Transported to the Intensive Care Unit. Anesthesiology Research and Practice. https://doi.org/10.1155/2016/7318137
3. Hummel, P. et al. (2008). Clinical reliability and validity of the N-PASS: neonatal pain,
   agitation, and sedation scale with prolonged pain. Journal of Perinatology, pp. 28, 55-60
   https://doi.org/10.1038/sj.jp.7211861
4. Jelacic, S. et al (2016). Intravenous Acetaminophen as an Adjunct Analgesic in Cardiac Surgery
   Reduces Opioid Consumption But Not Opioid-Related Adverse Effects: A Randomized Controlled Trial. Journal of Cardiothoracic and Vascular Anesthesia, 30(4), 997-1004. https://doi.org/10.1053/j.jvca.2016.02.010
5. National Council of State Boards of Nursing, Inc. (NCSBN). (2020). APN Consensus
   Implementation Status. https://www.ncsbn.org/5397.htm.
6. Ohio Associate of Advanced Practice Nurses (OAAPN). (2016). Prescriptive Authority
   Reminders. Retrieved from https://oaapn.org/2016/04/prescriptive-authority-reminders/.
7. Ohio Associate of Advanced Practice Nurses (OAAPN). (2018). APRN Practice Law Update
   OAAPN 2018. [PowerPoint] Retrieved from https://cdn.ymaws.com/oaapn.site-ym.com/resource/resmgr/education/2018nwo/Law_and_Rule_Update.pdf.
8. Taketomo, C., Hodding, J., Kraus, D. (2019). Lexicomp Pediatric & Neonatal Dosage
   Handbook: An Extensive Resource for Clinicians Treating Pediatric and Neonatal Patients (26th Edition). Wolters Kluwer Clinical Drug Information, Inc.

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