Basic - Physiology Flashcards
Why doesn’t discontinuation of N2O improvement in hemodynamic stability in pts with CO2 embolism?
CO2 is MORE soluble than N2O
- CO2 will move out or be absorbed/buffered more quickly than N2O
*note, you should still turn it off and turn on 100% O2
Does ETCO2 increase or decrease with CO2 embolism?
Both
- Increase: 2/2 to vascular CO2 insufflation
- Decrease: 2/2 to hemodynamic instability
What is the purpose of preoxygenation prior to induction?
After passive exhalation, the remaining volume is the FRC.
- Goal is to increase FRC FiO2
- removing nitrogen from FRC increases O2 content available for apneic oxygenation (inc reserves)
Why is arterial oxygen content not affected by changes in PaO2?
It is more affected from hgb [ ] and oxyhemoglobin saturation of oxygen
The STATIC compliance of the respiratory system indicates what? When is it determined?
The “stiffness”
- lungs
- chest wall
At the end of inspiration when there is NO airflow, hence, “static”
- Plateau Pressure*
The DYNAMIC compliance of the respiratory system indicates what? When is it determined?
The “resistance”
Can be measured at any point during inspiration when there is airflow
- Peak Pressure *
______ is the inverse of compliance of the respiratory system
Elastance
What hormones are INCREASED during stress response?
Pituitary: GH, ACTH, Prolactin, AVP
Effect organs: cortisol, aldosterone, glucagon
*TSH, LH, FSH unchanged
The end product of (anaerobic / aerobic) metabolism are CO2 and water
anaerobic
(anaerobic / aerobic) metabolism utilizes glucose as the starting substrate
Both
- start with same initial reaction that convert glucose -> 2 pyruvate
aerobic metab: makes 30-36 ATP
Anaerobic: 2-4 ATP? (a lot less)
Vasopressin is also known as?
ADH
AVP (arginine vasopressin)
Where are V1 and V2 receptors located?
V1: vascular smooth muscle
V2: distal and collecting tubules
How is FRC affected by :
Height
Advanced age
Increased in both (nl is 3-4L)
Height
Advanced age
- loss of elastic lung tissue, lessens contractile force of lung -> moves balancing point to a higher lung volume
Causes of LOWered FRC
PANGOS
Pregnancy Ascites Neonatal GA Obesity Supine pos \_\_\_\_\_\_ decrease height
SYmpathetic cardiac innervation originates from ______.
Target receptor sites for sympathetic cardiac innervation are ____
T1-T4
a1, b1, b2
The closing of the mitral valve corresponds with which wave on the EKG?
R wave
The (Sympathetic / Parasympathetic) nervous system is the dominant nervous system involved in BRONCHOCONSTRICTION and inc mucus production
Parasympathetic
*norepi, which stim sympathetic nervous system is a potent bronchial sm dilator
How is LV contractility affected by sodium bicarb administration?
HCO3- Binds calcium -> Serum i-cal [ ] transiently decreases -> less contractility in LV
How is lactate production affected by sodium bicarb administration?
Acutely correct acidotic pH (raise it) -> INCREASE hgb affinity for O2 -> worsens hypoxia ->
Increase lactate production
How is hgb affinity for O2 affected by sodium bicarb administration?
INCREASES
- higher pH, shifts curve to LEFT
What hormones are activated in the lungs?
Angiotensin I
Arachidonic acid
What hormones are INactivated in the lungs?
- Adenosine
- ATP/ADP/AMP
- Bradykinin
- Endothelins
- Leukotrienes
- Norepi*
- PDG2, PGE2, PGF2
- Serotonin*
*everything else is unchanged
Carcinoid triad
Flushing
Diarrhea
R sided HF
Uosm : Posm _____ indicates prerenal oliguria
> 1.5
*normal plasma osm is 280-300
What does glucagon stimulate?
Glycogenolysis
Gluconeogenesis
Lipolysis
Total body water (60% body weight, 42L) is divided into _____ and _____
intracellular volume
- 2/3, 40% TBW
extracellular volume
- 1/3, 20% TBW
- interstitial fluid 75% of EVC
- plasma is 25% of ECV
The MAC-BAR is the value that blunts adrenergic responses to noxious sitm is ___% higher than std MAC
50%
The MAC-awake ist he MAC where voluntary reflexes (ie. no longer open eyes to command, shouting or shaking) is ____% of std MAC
15-50%
Common signs of hypoglycemia
*Inc in sympathetic dischrge, cortisol and glucagon release
Diaphoresis Tachycardia HTN AMS Sz
*If a pt is taking a BB, you may not see tachycardia or HTN
What is the haldane effect?
Inc ability of hgb to carry carbon dioxide from the tissues to the LUNGS for exhalation
- in low O2 [ ], hgb binds more strongly to CO2
- in high O2 [ ], CO2 dissociates from hgb, and inc PCO2
The _____ effect explains inc binding of CO2 for delivery to the lungs, the _____ effect explains decreased binding of O2 for delivery to the tissue
Haldane
Bohr
The _____ chemoreceptors increase ventilation when PaO2 (not PAO2 or SaO2) decreases through afferent impulses via the GLOSSOPHARYNGEAL nerve to CNS ventilation centers.
Carotid body
How sensitive are Carotid body chemoreceptors to anesthetic drugs (opioids, BDZ, volatile anes 0.1 MAC)?
Very sensitive
- can cause respiratory insufficiency
Similarities and Difference btwn Carotid Bodies and Carotid SInuses?
Both are located at carotid bifurcation and impulses are transmitted via branch of GLOSSOPHARYNGEAL N (Hering’s n.)
Carotid bodies are chemoreceptors
Carotid sinuses are baroreceptors
Bronchoconstriction is d/t (sympathetic / parasympathetic) stimulation that occurs through the ____ n.
parasympathetic
VAGUS n.
How do alpha and beta receptors affect bronchial airways?
alpha - bronchoconstriction
beta - bronchodilation
Synthetic liver fxn is best assessed via PT/INR which most closely correlates with factor ___ levels, which has a half life of ___ hours
VIIa (half life of 4 hours)
Increases in direct or unconjugated bilirubin is a sign of ____
disruption in bile removal
- ie. choledocolithiasis
Liver still has ability to convert unconjugated to conjugated bilirubin
Carotid body CHEMOreceptors are primarily responsive to ______
reductions in arterial partial pressure of oxygen (PaO2)
- ~ < 60 mmHg
*NOT affected by arterial oxygen sat (SaO2), arterial oxygen content (CaO2)
CO poisoning results in ____ shift in the oxygen-hemoglobin dissociation curve.
LEFT
Does increasing Hgb increase oxygen delivery?
Yes, it increases arterial oxygen content ->
increased oxygen delivery
Eq for Oxygen delivery (DO2) = CO x CaO2
*CaO2 is arterial oxygen content
Btwn the Child-Pugh score and MELD score, they both use:
bilirubin
INR
- how do they differ?
Child Pugh
- Synthetic fxn of liver (Albumin, PT)
- Presence of ascites or encephalopathy
MELD
- Creatinine
- more accurate predictor of short term mortality
How do these affect the oxygen-hgb oxygen curve?
- Methemoglobinemia
- CO poisoning
- HYPOphosphatemia (substrate for production of 2,3 DPG)
LEFT shift
- decreased oxygen delivery to tissue
- increased affinity for oxygen
What is the P50?
partial pressure of oxygen at which hgb is 50% saturated
- nl P50 is 27 mmHg
When does hypophosphatemia usually occur?
Secondary to sepsis malnutrition refeeding syndrome acute liver injury DKA
*left shift in hgb-diss curve
Hypercapnia following admin of O2 to a pt with COPD is primary d/t ____
V/Q mismatch (perfusion to alveoli with zero or low ventilation)
- driven by inhibition of hypoxic pulmonary vasoconstriction by high oxygen tensions in under-ventilated lung units
Why do we titrate saturations in Pts with COPD to 88-92%?
Hypoxic pulmonary vasoconstriction is the most efficient way to alter V/Q ratios to improve gas exchange
Too much O2 = oxygen induced hypercapnia (haldane effect)
What is the mixed venous oxygen saturation (SvO2)?
The percentage of oxygen bound to hgb in the blood returning to the R side of the heart (oxygen “left over” after body has extracted what it needs)
- data from pulmonary a. catheter (all the venous blood returning from the SVC, IVC, and coronary sinus)
- nl = 75%
When is mixed venous oxygen saturation (SvO2) DECREASED?
*(SvO2 = oxygen “left over” after body has extracted what it needs)
- Inc. oxygen consumption (hyperthermia, shivering, pain)
- Dec. Cardiac output (MI, hypovolemia)
- Dec. Hgb [ ]
- Dec. arterial oxygen sat (SaO2)
When is mixed venous oxygen saturation (SvO2) INCREASED?
*(SvO2 = oxygen “left over” after body has extracted what it needs)
- Inc hgb [ ] (blood transfusions)
- Inc arterial oxygen sat (SaO2)
- Dec total body O2 consumption (VO2) (cyanide tox, sepsis, CO poisoning, methemoglobinemia, hypothermia)
- Inc Cardiac output (sepsis)
*Body may be unable to extract oxygen
How does Norepi affect bronchial smooth muscle?
No sig change
- More selective for B1 > B2 (bronchial sm relaxation)
How does Muscarinic 3 stimulation affect bronchial smooth muscle?
Bronchial sm contraction
What is lusitropy? How does it affect the LV pressure-vol loop?
Myocardial relaxation
- downward shift in LV pressure-vol loop
How is chest wall compliance different in neonates compared to adults? Cons?
Chest wall compliance is higher (more pliable rib cage)
- Increases WOB since rib case provides less mechanical support
Hydromorphone metabolism and excretion?
Metabolism in liver via phase 2 glucuronidation –> hydromorphone-3-glucuronide –> renally excreted
- hydromorphone-3-glucuronide accumulates in CKD
- no analgesia
- neurotoxic
Morphine metabolism and excretion?
Metabolism in liver via phase 2 glucuronidation -> Morphine-3-glucuronide and Morphine-6-glucuronide –>
Both renally excreted
- Both can accumulate in pts with CKD
- M6G has analgesic properties, no neuro excitability (resp depression)
- M3G has neuroexcitability
Which requires a higher [ ] of anesthetic to prevent MAC50, direct laryngoscopy or ET intubation??
ET intubation
How does alpha 2 and beta 2 stim affect lipolysis?
alpha 2: Inhibit lipolysis
beta 2: stim lipolysis
- stress response = catecholamine inc lipolysis -> loss of fat and lean body mass
Why does rapid admin of normal saline cause a non-anon gap hyperchloremic metabolic acidosis?
Na+ and Cl- are both strong ions
- strong ion difference of 0 = no anion gap
- nl human plasma SID = 40, if you give rapid admin, you bring SID closer to 0 -> acidemia
The ____ equation is used in ECHOs to assess pressure gradient and area of mitral and aortic valves
Bernoulli’s equation
The _____ equation is used to calculate oxygen consumption. Gold std by which Cardiac output is calculated
Fick principle
________ equation is used to describe a chemical system at equilibrium (ie. bicarb and CO2 eq)
Le Chatelier’s principle
Depolarization causes an influx of ____.
The first and second step of action potential termination:
influx of Na+
_____________
1) Na channel inactivation
2) efflux of K+
How do LA work?
Reversibly binding VG Na channels
- prevent depolarization (influx of Na+)
How does the botulinum toxin work?
Prevent membrane fusion and release of ACh into the synaptic cleft
How does tetrodotoxin (puffer fish poison) work?
Inhibits VG fast sodium currents in myocytes
- inhibits Action potential propagation
How does Ciguatoxin (Reef fish poison) work?
Opens Na+ channels -> depolarization
How is CO2 primarily transported in blood?
- Dissolved CO2
- Bicarb
- Carbamino compounds (rxns with proteins)
Largest contributor to initial reduction in core temp during GA?
Redistribution of heat from core to periphery
- redistribution hypothermia
Second is Radiative heat loss to surroundings
How does stored pRBCs affect the hgb-dissoc curve?
LEFT shift (inc hgb affinity for O2, lower P50) - has less 2,3-DPG
Things that increase 2,3 DPG
RIght shift - decrease hgb affinity for O2
- HYPERphosphatemia
- HYPERthyroidism
- Anemia
- Liver cirrhosis
- Sleep apnea
- HF
- High altitude hypoxia
Mneumonic for R ward shift in oxy-hgb dissoc curve.
*(RIght shift - decrease hgb affinity for O2)
CADET Face Right Inc in: CO2 Acid 2,3 DPG Exercise Temp
How does HYPERnatremia affect MAC?
Increases
Why doesnt adding to the inspiratory or expiratory limb add dead space?
Limbs are one way, no gas mixing
Mneumonic to remember the amt of rebreathing in Mapleson circuits
Rebreathing during SPONTANEOUS ventilation:
Rebreathing during CONTROLLED ventilation:
Rebreathing during SPONTANEOUS ventilation: A > D > C > B
- All Dogs Can Breathe
Rebreathing during CONTROLLED ventilation: D > B > C > A
- Dead Bodies Can’t Assist
Fetal hgb shifts curve to the (Right / Left)
Left (inc hgb affinity for O2, lower P50)
- improves O2 delivery to the fetus from the placenta
Insulin has (catabolic/anabolic) effects
anabolic (builds up) stimulates uptake / storage of: - glucose - amino acids - fatty acids
it also INHIBITS catabolic processes below: - lipolysis - protein breakdown - ketone formation - oxidation of FA and AA \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ - glycogenolysis - gluconeogenesis
