PONV Flashcards
HOW DO OPIATES CAUSE PONV
DIRECT STIMULATION OF CRTZ
PONV RISK FACTORS?
FEMALE, HX PONV OR MOTION SICKNESS, POSTOP OPIATE USE, NONSMOKER, YOUNG, OBESE, ANXIOUS, LONG SURGERY, N2O, KETAMINE, ANY CHOLINESTERASE (IE NEOSTIGMINE), VA
WHERE IS CRTZ, CHEMORECEPTOR TRIGGER ZONE?
LOCATED IN THE AREA POSTREMA IN THE 4TH VENTRICLE. LOTS OF THE DRUGS THAT CAUSE NAUSEA DO IT HERE. IT IDENTIFIES ABSORBED TOXINS OR DISTURBANCES SUCH AS HYPOTENSION OR METABOLIC ACID-BASE CHANGES.
WHERE IS THE VOMITING CENTER?
MEDULLA
WHAT ARE THE 4 NEUROTRANSMITTERS FREQUENTLY IMPLICATED IN NAUSE AND VOMITING? THESE ARE ALSO THE TARGET OF MOST THERAPUTIC MODALITIES.
HISTAMINE, ACETYLCHONLINE, SERITONIN, DOPAMINE
WHAT DO H2 ANTAGONISTS DO? WHY ARE THEY GIVEN?
H2 RECEPTOR ANTAGONISM DECREASES THE GASTRIC HYDROGEN ION CONCENTRATION (ACID). HISTAMINE STIMULATES H2 RECEPTORS WHICH INCREASES cAMP WHICH ACTIVATES PROTON PUMP OF GASTRIC PARIETAL CELLS WHICH SECRETES H ION. GOAL OF TREATMENT IS TO REDUCE ACIDITY OF POTENTIALLY ASPIRATED CONTENT. THEY DONT PREVENT VOMITING, JUST PROTECT AGAINST ASPIRATION OF ACIDIC CONTENT.
WHAT IS ONE SERIOUS POTENTIAL CONCERN WHEN GIVING H2 BLOCKER?
H2 BLOCK MAY CAUSE UNOPPOSED H1 STIMULATION POTENTIALLY RESULTING IN BRONCHOCONSTRICTION.
WHAT DO H1 BLOCKERS DO?
ANIT NAUSEA AND MOTION SICKNESS. ITS AN ANTIHISTAMINE BUT HAS SOME SERITONIN AND ACETYLCHOLINE BLOCKING ACTIVITY AS WELL. CAN GET SOME SEDATION AND ANTIPARKINSONISM EFFECT. BENADRYL IS AN EXAMPLE OF H1 BLOCKER.
WHAT DOES ZANTAC DO?
H2 BLOCKER. PROPHYLAXIS AGAINST PULMONARY ASPIRATION. DOESNT AFFECT PH OF WHAT IS IN GUT ALREADY BUT WHAT GUT WILL PRODUCE AFTER DRUG IS GIVEN. FEW CNS SIDE EFFECTS AND INDUCING OF HEPATIC ENZYMES (UNLIKE CIMETIDINE).
WHAT DOES CIMETIDINE DO?
H2 BLOCKER. AKA TAGAMET. GREATER LIKELIHOOD OF CNS SIDE EFFECTS AND MORE DRUG INTERACTIONS THAN ZANTAC.
WHY IS NIZATIDINE GIVEN?
150MG BID GERD OR 300MG ACTIVE ULCER.
2 MAJOR DRUGS IN PHENOTHIAZINE CLASS FOR PONV?
COMPAZINE AND PHENERGAN. THEY INTERACT WITH DA IN CTZ AND POSSIBLY PRODUCE DOPAMINERGIC SIDE EFFECTS LIKE TARDIVE DYSKINESIA AND PARKINSONIAN EFFECTS.
WHAT DOES COMPAZINE/PROCHLORPERAZINE DO?
TREAT PONV BY DEPRESSING THE CRTZ. MAY CAUSE HYPOTENSION VIA ALPHA BLOCKADE. ELIMINATED BY LIVER.
WHAT EFFECTS DOES PHENERGAN PRODUCE?
SEDATION, ANTIEMETIC AND ANTICHOLINERGIC. EXTRAPYRAMIDAL SYMPTOMS ARE POSSIBLE.
WHAT ARE THE INDICATIONS AND CONTRAINDICATIONS FOR REGLAN/METOCLOPRAMIDE?
STIMULATES MOTILITY TO ACCELERATE GASTRIC EMPTYING. ANTAGONIZES DA IN CRTZ. HAS NO EFFECT ON GASTRIC ACIDITY OR REVERSE OPIATE EFFECTS ON MOTILITY. INCREASES ICP. CONTRAINDICATED IN PTS WITH INTESTINAL OBSTRUCTION, TAKING PARKINSONS MEDS, SEIZURE DISORDERS, OR DEPRESSION. DECREASE DOSE IN THOSE WITH RENAL INSUFFICIENCY…PRIMARY RENAL ELIMINATION. DO NOT ADMINISTER WITH PHENOTHIAZIDES OR BUTYROPHERNONES.
