pharm-ponv Flashcards
who is high risk for ponv
- females
- Fatties (obese)
- full stomach/ fatty foods
- history of PONV
- motion sickness, migraine
- anxiety
- use of post op opiates
who is least at risk for PONV
smokers
young,girls, non smoker, use of post op opiates has a___% chance of ponv
50%
what procedures have higher risk?
- craniotoy
- strabismus repair
- ENT/ T&A
- orthopedic shoulder repair
- certain cosmetic procedures (chest augmentation)
- intra-abdominal
- Laparoscopic procedures
- heria repair (especially under spinal) .
- GYN procedures
- orchiopexy
what does surgery length do to incidence of PONV
longer=more risk
rank the PONV causers (in order of highest incidence to lowest)
- general (gas and opiates)
- SAB
- regional
what drugs increase chance of PONV
- opiates (balanced anesthesia)
- nitrous
- ketamine
- anticholinesterases
- what conditons increase PONV
2. how does the treatment of this cause PONV
- pain can cause PONV
2. opiates to treat pain trigger the CRTZ in the brain and cause nausea (very important fact)
what 5 other conditions cause PONV?
- movement (thru vestibular stimulation)
- orthostatic hypotension/dehydraton
- hypoglycemia
- hypoxia
- oral intake too soon after procedure
what are the 3 acts of vomiting?
nausea
retching
vomiting
nausea
typically associated with decreased gastric motility and increased small intestine tone and reverse peristalsis in small intestine
retching:
“dry heaves”, spasmodic respiratory movements conducted with closed glottis causing herination of abdominal esophagus into thoracid cavity due to negative pressure (due to resp effort with glottis closed)
vomiting (phase 1)
when gastric and small intestinal contents are expelled
1. deep breath; glottis closes; larynx raises and opens upper esophageal sphincter; soft palate raises to close off posterior nares
vomiting phase 2
diaphragm contracts sharply downward; creates neg pressure in thorax which opens esophagus and distal esophageal sphincter
vomiting (phase 3)
simultaneous downward movement of diaphragm and contraction of abdomen walls squeezes the stomach elevating intragastric pressure. pylorus is closed and esophagus is open, vomit is expelled.
who is at risk for PONV?
- children and adolescents
- women (d/t gonadotropin and estrogen)
- history of PONV
- non smokers
- anxious persons/ anxiety
- obesity (d/t larger gastrc volume, higher chance of reflux, amount of fat soluble drugs accumulated, and gall bladder/gi disease
- Oral Intake: excess fatty foods (slows peristalsis), full stomach, currently intoxicated
- use of post op opiates
- history of motion sickness
can nauser be triggered from multiple things at once?
yes
what can stimulation of pharynx cause
N/V (ilicits emetic resopnse)
why does car/ motion sickness occur
labyrinthine (vestibular) apparats and auricular branch of the tympanum of the ear detects motion stimulus from histhamine or ACH receptors
- what is the name of the receptors that detect overdistention and altered gastric motility which can lead to N/V?
- In what organs of the abdomen are they located?
- mechanoreceptors
2. bladder, gall bladder, uterus
- where are chemical stimulus detectors located in the abdomen?
- what do they sense?
- hepatic portal vein detectors
2. chemicals in the venous drainage of gut
gastric and duodenal chemoreceptors detect what?
irritation from toxins such as serotonin
what nerve sends signals regarding nausea to the brain?
vagus
- vagus nerve from gut sends signal to ___,___ & ___ receptors in brain?
- what is the name of these areas of the brain?
- histhamine, cholinergic or enkephalin receptors
2. nucleus tractus solitarius; centros of postrema and subpostrema
what parts of the brain are affected by emotions, sights, smells or thoughts?
higher brain centers in the cortex and limbic system
- where is the chemoreceptor trigger zone (CRTZ , CTZ),
2. what does it do?
- located in the postrema on the floor of the fourth ventricle of brain;
- identify absorbed toxins, or disturbances (hypotension and metabolic acid-base changes)which is reflected as nausea and vomiting
what must coordinate in order for vomiting to occur?
afferent stimuli detect the need to vomit and coordinate the response in the vomiting center in the lateral reticular formation of the brainstem close to foruth ventricle.
what are the receptors that have a role in receiving emetic impulses?
histhamine, serotonin, opiod, muscarenic, and dopaminergic
how do antihisthamines block nausea?
antagonizes H1 & H2
what does H2 stimulation cause?
increased gastric hydrogen ion concentration
where are H2 receptors found besides the stomach/
in the CNS with some in the heart
how does a H2 blocker work?
blocking histhamine stimulation of H2 receptors prevents increases in cAMP (cAMP activates the proton pump of gastric parietsl cells which secrete H+ ion)
