Primer on sedation, analgesia and local anesthetic for the IR: Part 2

Note: The first part of this article, which covered levels of sedation and pre-procedural patient selection, appeared in the summer 2019 issue of IRQ.

Introduction

As interventional radiology becomes more clinically based, knowledge of pain management strategies becomes increasingly important. Pain management and sedation decisions for IRs begin at the initial patient consultation and continue through postprocedural recovery. The decision to consult anesthesia, sedate the patient unassisted or only provide local anesthetic is an important decision and all options should be considered. This article will review an IR’s role in analgesia, anxiolysis, sedation and consultation with an anesthesiologist, with knowledge of the guidelines set by the American Society of Anesthesiologists (ASA).

Intraprocedural management

The Joint Commission requires a minimum set of intraprocedural monitoring requirements for moderate sedation. These requirements include: blood pressure, EKG and pulse oximetry. Capnography is recommended and used routinely as it can detect respiratory compromise earlier than pulse oximetry.

These measurements should be documented every 5 minutes for IV sedation and every 15 minutes for oral sedation. There are additional requirements for deep sedation such as with propofol or etomidate, which must involve an anesthesiologist and, concurrently, additional monitoring requirements including temperature and capnography. If the patient is intubated then exhaled and inhaled anesthetic gas concentrations, circuit low-pressure alarm and ventilator parameter are required.1,2,3

Local anesthetics are used in the majority of IR procedures. Knowledge of the correct dose and the symptoms of systemic toxicity is vital. Local anesthetics in low doses may cause vasoconstriction. However, in moderate to high doses, they will result in vasodilation. Cocaine is the only local anesthetic that will cause vasoconstriction at all doses. The initial symptoms of local anesthetic toxicity are dizziness, tinnitus, “funny taste,” or tongue and circumoral parathesias. However, the first sign may be cardiotoxicity especially with bupivacaine. Toxicity may cause excitatory symptoms from a blockade of inhibitory pathways including agitation, muscle twitching and seizures. An increased PaCO2 can lower the seizure threshold and patient’s on CNS depressants such as benzodiazepines or on propofol will have a higher seizure threshold. Toxicity can result in respiratory arrest followed by cardiac depression. Pregnant patients are at an increased risk of cardiotoxicity. Table 5 describes commonly used local anesthetics and their properties.1,8,12,13

Response to medications in patients with a history of drug abuse can be unpredictable. A short acting benzodiazepine is commonly used with these patients. Reversal agents should only be used when absolutely necessary in these patients as it can result in severe withdrawal symptoms.15

A pediatric anesthesiologist should be consulted if the pediatric patient has an ASA Class IV-V, if the patient is special needs, or has airway abnormalities. Pediatric sedation and anesthesia privileges can differ between facilities, so it is important to check what the current recommendations are in the facility you are working in. IV sedation is preferred over oral sedation in pediatric patients as the onset of action is faster and more predictable, titration easier and recovery can be quicker.1,15

Postprocedural management

After sedation, patients are monitored until they return to their pre-procedural level of sedation and vital signs within acceptable limits. If a reversal agent was given, patient should be observed for at least 90 min after it was administered. There is a potential for “re-sedation” effect after reversal agents are given.1,2,3

Initial treatment of hypotension from hypovolemia: IV NS in 250–500 ml increments. If the patient is unresponsive, phenylephrine (40–100 mcg increments) or ephedrine (5–10 mg increments) can be given.1,9

Initial treatment of hypertension: Labetalol (5–10 mg), metoprolol (1–5 mg), hydralazine (5–10 mg) or nicardipine (0.2 mg) in increments can be used. A beta-blocker may be preferable if there is associated tachycardia.1,9

Postprocedural rigors: Warming measures if the patient is hypothermic, IV fluids, supplemental oxygen as needed and antibiotics should be given. Persistent rigors can be treated with IV Meperidine (Demerol) 25–50 mg. Meperidine is a synthetic opioid; however, it is a weak analgesic. It can increase a patient’s heart rate due to structural similarity to atropine.

Postsedation nausea and vomiting: Risk factors include: Pre-procedural nausea, female sex, prior history of postoperative nausea and vomiting, history of motion sickness, nonsmoking, age less than 50 yr or intended administration of opioids for postoperative analgesia including intraoperative medications whose effects extend into the postoperative area. Adequate hydration during the procedure can help with nausea and vomiting. Different medications can be used to treat and prevent postoperative nausea and vomiting.

  • Ondansentron (Zofran): The first-line prophylaxis. There has been no significant difference demonstrated in postoperative nausea and vomiting with doses of 4 mg vs. 8 mg IV and therefore only 4 mg should be given.1,16
  • Dexamethasone: Highly effective in the prevention of postoperative nausea and vomiting. It has also been shown to cause significant pain relief, decreased opioid requirement (by 50%) and result in a shorter hospital stay. The benefits of routine single-dose dexamethasone use have been shown to outweigh the minimal risks in most situations. A single prophylactic dose of dexamethasone prior to uterine artery embolization for symptomatic fibroids or adenomyosis or prior to transarterial chemoembolization for hepatocellular carcinoma can decrease postembolization syndrome.1,16,17,18,19,20
  • Metoclopromide (Reglan): The ASA states that it should not be used for postoperative nausea or vomiting as the high dose needed for relief of nausea and vomiting would have a high risk of side effects.1
  • Scopolamine transdermal patch: Can be placed in patients at an increased risk of postoperative nausea and vomiting. It is placed the night prior to the procedure and has antinausea effects for 24 hr. The patch should be removed before an MRI to prevent skin burns.

The Society for Ambulatory Anesthesia (SAMBA) recommendations for postoperative nausea and vomiting in patients over 18 yrs old is to administer prophylactic therapy with a combination of two or more medications for patients at high risk (three or more risk factors). Recommended medications are listed in Table 6.1

The American Pain Society provides recommendations for postprocedural pain management that are relevant to IR procedures. These recommendations include:1,15

  • Give acetaminophen and/or NSAIDs as part of multimodal analgesia around the clock. It has been shown to cause a 30–50% reduction in opioid use.
  • Pre-procedural Celecoxib (Celebrex) in adult patients without contraindications (significant cardiac or renal disease) should be considered. It has been shown to decrease the postoperative pain score by 1.5 times.
  • It is recommended to use PO over IV opioids and the intramuscular route for analgesics should be avoided. It is not recommended to use routine basal rates for PCA (patient controlled anesthesia pumps).
  • Gabapentin/Pregabalin for multimodal postoperative analgesia should be considered, as they are associated with a 30% reduction in opioid requirements and decrease in postoperative nausea and vomiting.

Postprocedural pain control should involve a multimodal drug regimen. Common medications that can be used are listed in Table 7.10,15

Summary

  1. A multidose regime for sedation is recommended. Quick access to reversal and rescue medications are necessary including naloxone for opioid reversal and flumazenil for benzodiazepine reversal.
  2. Postprocedural pain control should involve a multimodal drug regimen and should include Tylenol and/or NSAIDs.
  3. Ondansentron is first line and dexamethasone is second line for postoperative nausea and vomiting prophylaxis. Single prophylactic dose of 4–10 mg dexamethasone significantly improves postoperative nausea and vomiting and can decrease postembolization pain.

Conclusion

Interventional radiologists must have a good understanding of sedation, analgesia and local anesthesia as well as know their limitations while caring for patients. It is important to understand the value of anesthesia consultation and when it is in the best interest of the patient.

References

  1. Standards and Guidelines. American Society of Anesthesiologists. Retrieved from asahq.org/standards-and-guidelines.
  2. The Joint Commission. Comprehensive accreditation manual for hospitals: The official handbook. Oakbrook Terrace, Ill.: The Joint Commission, 2018.
  3. American College of Radiology and Society of Interventional Radiology. ACR-SIR practice guideline for sedation/analgesia. American College of Radiology website. acr.org/-/media/ACR/Files/Practice-Parameters/Sed-Analgesia.pdf. Revised 2015. Accessed Aug. 25, 2018.
  4. Araujo, BL, Theobald, D. (2017). Letter to the Editor: ASA Physical Status Classification in Surgical Oncology and the Importance of Improving Inter-Rater Reliability. Journal of Korean Medical Science, 32(7), 1211. doi:10.336/jkms.2017.32.7.1211.
  5. Nygren, J. et al. (1998). Preoperative oral carbohydrate administration reduces postoperative insulin resistance. Clinical Nutrition, 17(2), 65-71. doi:10.1016/s0261-5614(98)80307-5.
  6. Gross J, Bailey P, Connis R et al. Practice Guidelines for Sedation and Analgesia by Non-Anesthesiologists. Journal of the American Society of Anesthesiologists. 2002, Vol.96, 1004–1017.
  7. Riad W et al. Neck circumference as a predictor of difficult intubation and difficult mask ventilation in morbidly obese patients: A prospective observational study. European Journal of Anesthesiology 2016.
  8. Jonathan O, Richard B, and Shashin D. Moderate Sedation: What radiologists need to know. American Journal of Roentgenology 2013; 201: 941–946.
  9. Martin M, Lennox P. Sedation and analgesia in the interventional radiology department. Journal of Vascular Interventional Radiology. 2003; 14 :111–1128.
  10. US Food and Drug Administration. accessdata.fda.gov/scripts/cder/daf/.
  11. Cotsen M R et al. Efficacy of ketamine hydrochloride sedation in children for interventional radiologic procedures. AJR Am J Roentgenology. 1997; 169(4) 19–1022.
  12. Johnson S. Sedation and Analgesia in the Performance of Interventional Procedures. Seminars in Interventional Radiology. 2010;27(4):368-373. doi:10.1055/s-0030-1267851.
  13. Linsey E. et al, Local anaesthetic systemic toxicity, Continuing Education in Anaesthesia Critical Care & Pain, Volume 15, Issue 3, June 2015, Pages 136–142, doi.org/10.1093/bjaceaccp/mku027.
  14. Noel-Lamy, Maxime et al. Intraarterial lidocaine for pain control in uterine artery embolization: A prospective, randomized study. Journal of Vascular and Interventional Radiology, Volume 28, Issue 1, 16–22.
  15. Chou R, Gordon D, de Leon-Casasola O. Management of postoperative pain: A clinical practice guideline from the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists’ Committee on Regional Anesthesia, Executive Committee, and Administrative Council. The Journal of Pain; 2016; Vol 17 No2; 131–157.
  16. Kakodkar, PS. (2013). Routine use of dexamethasone for postoperative nausea and vomiting: The case for. Anaesthesia, 68(9), 889–891. doi:10.1111/anae.12308.
  17. Gupta, B. (2017). Role of dexamethasone in peri-operative anesthesia management: A review of literature. Anesthesiology–Open Journal, 2(2), 33–39. doi:10.17140/aoj-2-114.
  18. Kim, S et al (2015). The effects of single-dose dexamethasone on inflammatory response and pain after uterine artery embolisation for symptomatic fibroids or adenomyosis: A randomised controlled study. BJOG: An International Journal of Obstetrics & Gynaecology, 123(4), 580–587. doi:10.1111/1471-0528.13785.
  19. Yang, H et al. (2017). Dexamethasone prophylaxis to alleviate postembolization syndrome after transarterial chemoembolization for hepatocellular carcinoma: A randomized, double-blinded, placebo-controlled study. Journal of Vascular and Interventional Radiology, 28(11). doi:10.1016/j.jvir.2017.07.021.
  20. Waldron, NH, Jones CA, Gan TJ, Allen TK, Habib AS. (2013). Impact of perioperative dexamethasone on postoperative analgesia and side-effects: Systematic review and meta-analysis. British Journal of Anaesthesia, 110(2), 191–200. doi:10.1093/bja/aes431.