Chapter 16 - Critical Care II Flashcards
Diagnosis of significant organ failure of the lung?
- need for mechanical ventilation
- PaO2/FiO2 ratio <300 for 24 hours
Diagnosis for significant organ failure of cardiovascular?
need for pressors to maintain adequate tissue perfusion Or Cardiac Index <2.5
Diagnosis of significant organ failure of the kidney?
- creatinine >2x baseline on 2 consecutive days
- dialysis
Diagnosis of significant organ failure of Liver?
bilirubin >3 on 2 consecutive days
PT >1.5 control
Diagnosis for significant organ failure of CNS?
glasgow coma scale <10 without sedation
Diagnosis for significant organ failure of coagulation?
platelets <100 need for factor replacement
Diagnosis for significant organ failure of host defenses?
WBC <1000 OR invasive infection including bacteremia
aspiration of what pH causes injury?
pH 2.5 and volume >0.4cc/kg causes increased damage
what is Mendelson’s Syndrome?
chemical pneumonitis from aspiration of gastric secretions most common site is posterior portion of RUL and superior portion of RLL
What is atelectasis?
bronchial obstruction and respiratory failure main causes most common cause of fever in first 48h fever tachycardia increased in pts with COPD, upper abdominal surgery tx with incentive spirometer
What can throw off pulse ox?
- nail polish
- dark skin
- low-flow states
- ambient light
- anemia
- vital dyes
What causes pulmonary vasodilation?
bradykinin PGE1 prostacyclin NO
What causes pulmonary vasoconstriction?
- histamine
- serotonin
- TXA2
- epinephrine
- norepinephrine
- hypoxia
- acidosis
how do you alkalosis via lungs?
pulmonary vasodilator
how do you treat acidosis via lungs?
pulmonary vasoconstrictor
What vasodilatory drugs cause pulmonary shunting?
Nipride, nitroglycerin, nifedipine
Increases in NO cause vasodilation. In the lungs, this causes an increase in flow w/o increasing oxygenation, ie shunting.
An important side effect is cyanide toxicity - tx amyl nitrite, sodium nitrate, sodium thiosulfate
What is the most common cause of postoperative renal failure?
hypotension
What percentage of nephrons need to be damaged before you have renal dysfunction?
70%
What is FeNa?
(Naurine/Naplasma) / (Crurine/Crplasma)
- < 1% is prerenal - the kidney is working, it is still trying to hold Na in response to a decrease of flow into the glomeruli
- > 2% is ATN or postrenal - the kidney is not working well
- intermediate could be either
what are the findings in prerenal acute renal failure?
- FeNa < 1% (aldosterone)
- urine osmolality >500 mOsm (ADH)
- BUN/Cr ratino >20
What do do with oliguria?
1st- make sure patient is volume loaded 2nd- try diuretic trial 3rd dialysis if needed
What are the indications for dialysis?
fluid overload increasing K metabolic acidosis uremic encephalopathic uremic coagulopathy poisoning
What is the benefit of CVVH?
- slower
- good for ill patients who cannot tolerate volume shifts
- Hct increases by 5-8 for each liter taken off
What are the advantages of intermittent hemodialysis?
- lower risk of systemic bleeding
- facilitates transport for other interventions
- more suitable for severe hyper K
- lower cost
What are the disadvantages of intermittent dialysis?
availability of dialysis staff more difficult hemodynamic control inadequate frequency fluid control nutrition issues not good for increased ICP no removal of cytokines complement activation
what are the benefits of continuous renal replacement therapy?
better hemodynamic stability fewer cardiac arrhythmias improved nutritional support better pulmonary gas exchange better fluid control
disadvantages of continuous renal replacement therapy?
vascular access problems higher risk of systemic bleeding long term immobilization more filter problems cost
What causes release of renin?
- decreased pressure sensed by juxtaglomerular apperatus
- increased NA sensed by macula densa
- beta adrenergic stimulation
- hyperkalemia
What does renin cause?
- renin - angiotensinogen (from liver) to angiotensin I
- ACE - angiotensin I to II
- angiotensin II - adrenal cortex release of aldosterone
Where does aldosterone act?
distal convoluted tubule. Reabsorbs more water by increased Na/K ATPase on membrane- potassium secreted
What are other effects of angiotensin II?
Everything to increase BP and blood glucose
- inc vasoconstriction
- inc HR and contractility
- inc vascular permeability
- inc glycogenolysis and gluconeogenesis
- inh renin
What is atrial natriuretic peptide?
released from atrial wall with dilation inhibits Na and water resorption in the collecting ducts vasodilator
What is ADH
vasopressin. released by posterior pituitary gland when osmolality is high -acts on collecting ducts -vasoconstrictor
What part of nephron controls GFR?
efferent limb
How are NSAID’s nephrotoxic?
inhibit prostaglandin synthesis resulting in renal arteriole vasoconstriction
How are aminoglycosides nephrotoxic?
direct tubular injury and later renal vasoconstriction
How is myoglobin nephrotoxic?
direct tubular injury tx by alkalinizing urine
How is contrast dye nephrotoxic?
direct tubular injury premedicate with fluid, N-acetylcysteine
What precludes dx of brain death?
- uremia
- low temp
- BP <70/40
- apnea test failure
- phenobarbitol/pentobarbitol
- metabolic derangements
What must you have for brain death?
- must exist for 6-12 hours
- unresponsive to pain
- absent caloric oculovestibular reflex
- absent oculocephalic reflex + apnea test
- no corneal reflex/gag reflex
- fixed/dilated pupils
- EEG - electrical silence
- MRA - no flow
- Can still have deep tendon reflexes
What is the apnea test?
- disconnect from ventilation
- CO2>60 or increase >20 is positive
- if arterial pressure drops to <60 or desaturates, test terminated
How is carbon monoxide dangerous?
- falsely increase O2 sat reading on pulse ox
- binds hemoglobin directly
- can usually correct with 100% O2 on ventilator
- abdnormal carboxyhemoglobin is >10%, >20% in smokers
What else can cause methemoglobinemia other then CO?
nitrites tx with methylene blue
What is the order of clinical illness polyneuropathy?
motor>sensory occurs with sepsis, can lead to failure to wean from vent
What does xanthine oxidase do? where is it from?
in endothelial cells, forms toxic oxyten radicals with reperfusion also involved in metabolism of purines and breakdown to uric acid
DKA sx?
nausea, vomiting, thirst, polyuria abdominal pain, increased glucose, increased ketones, decreased Na, increased K tx w bicarb for pH>7.25
EtOH withdrawal?
HTN tachycardia delirium seizures Tx: thiamine, folate, Mg, K, B12, ativan
ICU psychosis?
generally occurs after third post op day, preceded by lucid interval need to rule out metabolic and organic causes
