CRIBS Physio/Path Flashcards
What is the equation for CO?
CO= HR x SV
What is the Fick Principle?
CO= rate of O2 consumption/ (arterial O2 - venous O2)
What are the 2 equations for MAP?
- MAP= CO x TPR
2. MAP= 2/3 diastolic + 1/3 systolic
What is pulse pressure?
systolic - diastolic
- our pt’s is 158 - 88= 70 mmHg
- normal= 40 mmHg
What volume is proportional to pulse pressure?
Stroke Volume
*SV= EDV - ESV
What is ejection fraction?
EF= SV/EDV -OR- EF= (EDV-ESV)/EDV
** What is Laplace’s Law of wall TENSION for cardiac vessels (cylindrical) and for alveolar (spherical), respectively?
- CARDIAC (cylindrical): wall tension= pressure x radius
- aka the larger the vessel radius, the larger the wall tension must be in order to withstand a given internal fluid pressure.
ALVEOLAR (spherical): collapsing pressure = 2(tension)/radius
*surfactant reduces surface tension (aka decreases collapsing pressure).
*** What is Laplace’s Law of wall STRESS?
wall stress= (pressure x radius)/(2 x wall thickness)
What is inversely proportional to pulse pressure?
- arterial compliance
What part of the respiratory tree participates in gas exchange?
- respiratory bronchioles and alveolar air sacs
Where does fluid enter the lung in a pt who is supine?
- posterior segment of right upper lobe
Where does fluid enter the lung in a pt who is standing upright?
- basal segments of right lower lobe
Where does the common carotid biFOURcate?
- C4
Where does the trachea biFOURcate?
- T4
Where does the abdominal aorta biFOURcate?
- L4
What is normal tidal volume?
- 500 mL
What is the equation of physiologic dead space of conduction airways?
- VT x (PaCO2- PECO2)/ PaCO2
- Taco, Paco, Peco, Paco
- VT= tidal volume
What is Minute ventilation (VE)?
- total volume of gas entering lungs per minute (VE= VT x RR).
- VT= tidal volume
- RR= respiratory rate (12-20 breaths per minute)
With what is chronic HTN associated?
- Charcot-Bouchard microaneurysms= subarachnoid hemorrhage
How do B-blockers work?
- B-receptor is a Gs protein-coupled receptor linked to cAMP. B-blockers will decrease cAMP and PKA, thus decreasing Na+ and Ca2+ current, and decreasing the slope of phase 4 and phase 0, thus decreasing AV node conduction.
What are the side effects of statins?
- hyopathy and hepatitis
To what is blood flow directly proportional?
(vessel radius)^4
What is inversely proportional to (vessel radius)^4?
resistance
What is the equation for flow?
- (P1-P2)/R
* R=nL/(r^4)
What is a rare and serious ADR of ACE inhibitors?
- ANGIOEDEMA due to increased bradykinin, which increases vascular permeability leading to tongue, lips, or eyelid swelling.
What is normal right ventricular pressure?
- 25/5
What is normal pulmonary artery pressure?
- 25/10
What is normal pulmonary capillary wedge pressure and what does this reflect?
10
*reflects LVDP
Where do you place a chest tube?
- 4th or 5th intercostal space along midaxillary line
What happens in the lung when you have a decrease in PAO2 (alveolar O2)?
- shunting of blood (vasoconstriction) away form hypoxic areas and toward well-ventilated regions of the lung; unique to lung
What does pulse oximeter read and how?
- the percentage of Hb in the blood that is saturated with Oxygen. It does this via 2 wavelengths of light through the finger to a photodetector. It measures the changing absorbance at each of the wavelengths, allowing it to determine the absorbances due to the pulsing arterial blood alone.
How many Hb molecules are found in one RBC?
- 250 million and each hemoglobin molecule can bind 4 O2 molecules= 1 billion O2 molecules per RBC.
What would be our patient’s A-a gradient with opioid use, leading to respiratory depression?
- result is HYPOVENTILATION, which would lead to a NORMAL A-a gradient. The only other situation we would see a normal A-a gradient is in high altitude.
- normal A-a gradient= 5-15 mm Hg bc 105-100= 5
What could cause an increased A-a gradient?
- V/Q mismatch (airway obstruction= shunt due to vasoconstriction away from hypoxic area. giving O2 doesn’t help here bc there is an airway obstruction so the O2 won’t get to the alveoli anyway; or blood flow obstruction= physiologic dead space).
- Difffusion limitation (ex. fibrosis)
- R to L shunt
Is hemoglobin in the relaxed or taut form in the lungs?
- relaxed, and has high affinity for O2.
* remember it’s taut in tissues.
What is the response of normal PERIPHERAL chemoreceptors (carotid and aortic bodies)?
- sense decreased PO2 (less than 60 mm Hg), increased PCO2, and increased H+. This leads to vasodilation and increased cerebral blood flow and increased RR to blow off excess CO2.
What 4 herniation syndromes could occur with a supratentorial hematoma?
- Cingulate= compresses anterior cerebral artery.
- Transtentorial= caudal displacement of brain stem, leading to duret hemorrhages.
- Uncal= compresses ipsilateral CN 3 (down and out gaze) or PCA (contralateral homonymous hemianopia).
- Cerebellar tonsillar= coma and death with brain stem compression.
What do upper motor signs show?
- everything up (tone, DTRs, toes; Babinski).
What is Wernicke aphasia?
- Wernicke is wordy, but makes no sense. Superior temporal lobe of gyrus. Comprehension is impaired but speech is fluent.
What sensore and motor areas would be affected with a sub-parietal hematoma?
- upper limb and face, contralateral paralysis and sensory loss.
What is Gerstmann syndrome?
- dominant parietal cortex lesion leading to agraphia, acalculia, and finger agnosia, left-right disorientation.
What are the 3 classes of shock?
- hypovolemic= preload problem (hemorrhage or dehydration).
- cardiogenic/obstructive= contractility problem (MI, arrhythmia; pneumothorax, PE, cardiac tamponade)
- septic/anaphylactic/neurogenic= afterload problem
