Postoperative Nausea and Vomiting (PONV)

1. Postoperative Nausea and Vomiting (PONV) Presented by: Danyel Dorn RN, MSN, CPN, Clinical Nurse Educator-Pediatric Service Line

2. Purpose • The registered nurse will demonstrate knowledge of physiology, symptomology, influencing factors and detrimental effects of nausea and vomiting, identify appropriate nursing interventions to alleviate nausea and vomiting to provide comfort for the pediatric patient.

3. Competency Statement • Provide perianesthesia management of postoperative nausea and vomiting (PONV) in the pediatric patient.

4. Pathophysiology • The vomiting center (VC) or emetic center (EC)is located in the lateral reticular formation of the medulla. • VC receives impulses from the GI track, cerebral cortex of the brain, vestibular apparatus and the chemoreceptor trigger zone (CTZ).

5. Pathophysiology Cont. • GI tract: chemoreceptors and stretch receptors in the gut respond to stimulation to trigger nausea and vomiting by way of vagal nerve response • Serotonin, acetylcholine, histamine and substance P are major neurotransmitters involved in stimulating these receptors • Cerebral cortex: associated structures in the limbic system which can alter complex experiences such as taste, sight and smell as well as memory (involved in anticipatory nausea) and emotion

6. Pathophysiology Cont. • Vestibular apparatus: motion and body position that are sensed through the vestibular apparatus and can produce disequilibrium • Chemoreceptor trigger zone: if the CTZ senses toxic substances in the blood, nausea is experienced and the vomit reflex initiated • CTZ has four major receptors: dopaminergic, histaminic, muscarinic (cholinergic) and serotonergic • Dopamine acts on D2 receptors-opioid related nausea appears to be most related to stimulation of D2 receptors • Serotonin acts on 5HT3 receptors

7. Pathophysiology Cont. • Nausea: subjective and uncomfortable experience of an impending urge to vomit • Associated with symptoms such as pallor, tachycardia, diaphoresis and excessive salivation • Vomiting: objective experience which includes contraction of abdominal muscles, descent of diaphragm, opening of gastric cardia, expulsion of stomach contents through mouth

8. Stimulating Factors • Hypotension, hypoxia, abdominal distention, increased oral secretions, anxiety or stress, pain, especially visceral or pelvic, dehydration, hypovolemia and hypotension simulating dizziness or motion • Fluid/electrolyte imbalance, noxious sights, smells, sounds, increased intracranial pressure • Chemical agents: anesthesia, opioids, chemotherapy, other medications

9. Consequences of PONV • Patient discomfort, prolonged hospitalization, increased cost of care, aspiration, dehydration, electrolyte imbalance (metabolic alkalosis, hyponatremia, hypokalemia), disruption of surgical incisions, formation of hematomas, increased ICP • Side effects of antiemetic’s include: increased anxiety, pain, sedation, extrapyramidal effects

10. At Risk for PONV • Children have twice the vomiting incidence of adults • Pediatric PONV is generally referred to as “POV” since it is frequently difficult for children to identify and describe nausea • Current scoring tools for predicting POV are specific to adults and few tools have been validated for assessing pediatric risk

11. At Risk for PONV • Surgery lasting more than 30 minutes • Age • Greater than 3 years old • Rare in children younger than 2 • School age children and adolescents have higher risk than toddlers • History of POV/relative with PONV (mother, father, siblings)

12. At Risk for PONV • Types of surgery • Strabismus surgery • Adenotonsillectomy • Herniorrhaphy • Laparotomy • Middle ear surgery • Orchiopexy and penile surgery • Female patients 11 years and older • History of motion sickness • Forcing children to drink fluids postoperatively • Intraoperative or postoperative opioid administration

13. Prophylactic Measures • In general consider the baseline risk in the selection of the number and type of prophylactic interventions • Children who are at moderate or high risk for PONV/POV should receive combination therapy with at least two prophylactic drugs from different classes

14. Prophylactic Measures • Anesthesia considerations: total intravenous anesthesia • Pharmacologic therapies: Zofran (not indicated in neonates), Granisetron, Tropisetron, Dexamethasone, Dimenhydrinate • Therapeutic interventions: appropriate hydration, additional use of oxygen therapy

15. Prophylactic Measures • Pain management • Use of multimodal approach to pain managemnet including the use of local/regional anesthesia • Consider the use of non-steroidal anti-inflammatory drugs • Consider regional anesthesia • Consider use of intraoperative opioids for their dose-sparing effect on inhalation agents • Minimize the use of postoperative opioids • Complementary interventions have not been well studied in children, but may be helpful: P6 acupoint stimulation, aroma therapy and deep breathing

16. Postoperative Management • Assess for postoperative nausea on admission, discharge and more frequently as indicated (high risk patient, after administration of opioid or antiemetic) • Select and administer appropriate rescue antiemetic's and monitor for effects (not recommend to use the same antiemetic that was used prophylactically) • Consider aromatherapy, provide supplemental oxygen, acupressure techniques

17. Additional Nursing Interventions • Monitor BP, HR, RR and SPO2 • Obtain baseline vital signs to establish reference point • Stimulation of the parasympathetic system through nausea with retching (vagal stimulation) may produce bradycardia and hypotension

18. Positioning • If the child is unconscious or there is a possibility of a compromised airway or loss of protective reflexes, position in slight Trendelenburg and lateral position (providing direct visualization of the child) to facilitate drainage of contents from oral cavity, decreasing the possibility of aspiration • If the child as abdominal distention or history of GERD, keep the head of the bed elevated

19. Assessment • Assess for aspiration, if adventitious sounds are audible and there is a decrease in the SpO2, aspiration should be suspected • Oral/tracheal suctioning to clear the airway • Support or splint surgical wound during active retching and vomiting • Assess patency and securement of all tubes and IV lines • Report excessive or prolonged N/V • Restricting postoperative intake following anesthesia does not reduce the incidence of vomiting in children, allow child to choose when to start taking fluids • Document and communicate per hospital protocol

20. Reference • ASPAN (2016). A Competency Based Orientation and Credentialing Program for the Registered Nurse Caring for the Pediatric Patient in the Perianesthesia Setting.

21. Answers • B • B • A • C • B • B • D