Intraoperative nausea and vomiting IONV during cesarean section

Intraoperative nausea and vomiting (IONV) during cesarean section under regional anesthesia R1 李怡慧 Introduction      Incidence of IONV Physiology of nausea and vomiting Risk factors Causes and related prophylactic measures Treatment Incidence   Non-obstetric surgery: 7~42 % Obstetric surgery: up to 80%     Anesthetic technique Preventive measures Therapeutic measures Stages of the surgical procedure Physiology of Nausea and Vomiting  Chemoreceptor trigger zone (CTZ)  Highly vascularized  Vomiting center      Vagal sensory fiber in the GI tract Labyrinth via the vestibular nuclei Cortex CTZ Intracranial pressure receptors Risk Factors  Hormonal change     Progesterone, Estrogen Impaired GI motility Incompotent LES Neurovestibular system and emetic center  Mechanical compression Risk Factors  Increased odds of IONV under SA     Addition of vasoconstrictor to local anesthetics Block height ≧ T5 Baseline HR ≧ 60 bpm History of car sickness and hypotension Causes  Anesthetic causes    Hypotension Increased vagal activity Neuraxial or parenteral opioids Surgical stimuli Surgical bleeding Medications Motion at the end of surgery  Non-anesthetic causes     Hypotension    Most important etiological factors Cerebral hypoperfusion and brainstem ischemia Gut ischemia and emetogenic substances release Hypotension  Prevention   Lateral uterine displacement Fluid preloading Crystalloid vs. colloid  L/R, 10ml/kg    Leg wrappings Prophylactic vasopressors Ephedrine, dosage  Phenylephrine  Hypotension    Strict control of BP can reduce intraoperative emetic symptoms Epidural anesthesia: Better hemodynamic control Combined spinal-epidural technique Vagal Hyperactivity    Sympathetic block Relative overactivity of the vagus Vagolytic agents  Glycopyrrolate Surgical Stimuli      Exteriorzation of the uterus Intra-abdominal manipulation/exploration Peritoneal traction during closure Visceral pain Prevention   Neuraxial opioids Appropriate surgical technique Quality of Block and Neuraxial Adjuvants  Visceral nociception   Spinal-opioid receptors δ-opioid receptors Unmyelinated C-fibers Addition of lipophilic neurxaial opioids Cephalad spread in the CSF  Vascular uptake  Sensitization of the vestibular system to motion  Decreased gastric emptying   Visceral pain   Intrathecal Adjuvants  Fentanyl     Decrease in somatic and visceral pain Less requirement of supplemental IV opioids Lower incidence of hypotension Dosage   Sufentanil Morphine  Increased the incidence of PONV in a dosedependent manner Intrathecal Adjuvants  Dimorphine   High lipid solubility, low pKa, slow rate of deaxetylation within neural tissues 0.3 mg Increased the incidence of IONV  Meperidine  Intrathecal Adjuvants  Clonidine    Activate α2-adrenergic receptors in the dorsal horn → Inhibit substance-P release Dose-dependent hypotension and sedation Increased the incidence of IONV Inhibit CSF cholinesterase → Enhance analgesia Increased the incidence of IONV  Neostigmine   Epidural Adjuvants  Fentanyl   Decrease intraoperative pain scores and IONV during exteriorization of the uterus Minimun effective dose: 50μg 20~30μg Rapid vascular uptake PONV  Sufentanil    Morphine  Epidural Adjuvants  Dimorphine  Higher incidence of PONV  Hydromorphine  No clinical benefit  Meperidine Uterotonic agents  Oxytocin   As a result of hypotension NO, ANP Highest incidence Dopaminergic & serotinonergic -adrenergic receptors  Ergot alkaloids    Prostaglandins  Stimulating smooth muscles of GI tract Antibiotics  Overall incidence of nausea and vomiting has note been reported Motion    Susceptibility to vestibular-mediated sickness Lowers the threshold for nausea and vomiting with motion Histamine H1 & muscarinic pathways Antiemetic Agents  Benzamides (Metoclopramide)     Antagonism of dopaminergic receptors in CTZ Increase resting tone of LES Antagonism of 5-HT3 receptors Side effects Antiemetic Agents  Antihistamines (Dimenhydrinate)    Blocking H1 receptors Inhibiting the intergrative function of vestibular nuclei Widely used for hyperemesis gravidarum Antiemetic Agents  Butyrophenones (Droperidol)    Act on dopamine receptors in the CTZ Most popular and effect drug for 30 years Side effects Antiemetic Agents  Serotonin antagonists (Ondansetron/Granisetron)  5-HT3 receptors at CTZ and vagal nerve terminals Modulate neurotransmitter or glucocorticoid receptor density in the nucleus of the solitary tract, the raphe nucleus, and the area postrema Safely used in the treatment of PONV  Steroids   Propofol    Prophylactic antiemetic efficacy at subhypnotic dose (1mg/kg/hr) Direct antiemetic effect A weak 5-HT3 antagonistic effect Acupressure     Non-pharmacological & non-invasive method Peripheral nerve stimulation Enhancing gastric motility Comparable to metoclopramide in decreasing nausea during C/S Conclusion  Prevention      Strict BP control Optimal use of neuraxial opioids (fentanyl 10μg for spinal and 50μg for epidural) and limited use of systemic opioids Improvement of surgical technique Judicious and slow administration of uterotonic agents Avoid vigorous movements and sudden transfer Conclusion  Antiemetic agents treatment      Optimal use remains unclear Rescue use Metoclopramide (10~20 mg IV) Dimenhydrinate (25~50 mg IV) Ondansetron (4 mg IV)/Granisetron (4μg/kg) Thanks for Your Attention!