CABS: Regulation of respiration and drive and CLIN MED: PFT and ABG (incomplete) Flashcards
what determines pH
H+ concentration
what balances pH
CO2 and HCO3- concentrations
what is the calculation for pH
HCO3- / pCO2
how much CO2 do we produce per minute
200mL / Min
what triggers central chemoreceptors
CO2
how much more soluble than O2 is CO2
20x - will diffuse very quickly
what is the henderson hasselback equations
CO2 + H2O -> H2CO3 -> HCO3- + H+
what is the combination of CO2 + H20
carbonic acid (H2CO3)
what is the buffer of pH
bicarbonate
what controls the bicarbonate levels
kidneys
what is normal bicarb levels
24-26 mEq/L
what is the by-product of glucose and oxygen
carbon dioxide + water + ATP
what chemicals control involuntary breathing
CO2
H+
H2CO3
HCO3
pO2 - partial pressure O2
what are the different types of chemoreceptors
CO2 (periphery) and O2 receptors (peripherally and centrally located)
what occurs to the pH when the CO2 increases
pH will decrease (acidosis)
what is part of the respiratory center within the brain stem
Pons - pneumotaxic and apneustic center
Medulla - dorsal and ventral respiratory group
what is the pneumotaxic center
located in the pons
modify breathing rhythm that is set forth by the dorsal and ventral respiratory groups
helps with inspiration/expiration transition
what is the apneustic center
located in the pons
modify breathing rhythm that is set for by the dorsal and ventral respiratory groups
involved in inspiration
received input from stretch receptors
what the dorsal respiratory group (DRG)
primary control in respiratory drive
located in the medulla
chemical, mechanical and neural triggers
(at rest breathing)
what is the ventral respiratory group (VRG)
activated during times of increased effort
controls the rhythm of breathing
assists with inspiration and expiration
what signals initiate VRG
dopamine
at what point does O2 become the primary driver to influence respiratory rate
< 60
what do the chemoreceptors in the carotids detect
CO2 (and O2 if now) (and pH)
what are irritant receptors
react to noxious stimuli within the lung
located in the conducting airway epithelium
triggers cough reflex and bronchoconstriction
what is the function of the lung receptors
these will all send afferent stimuli to the dorsal respiratory group of the medulla
what are stretch receptors
lung receptors-assist with ventilatory rate/volume as the smooth muscles sense/react to over inflation/deflation
will stop continued inhalation to prevent barotrauma
what are J-receptors
lung receptors - sense pulmonary capillary pressure
react to pulmonary edema
what are j receptors most commonly associated with
left HF
- rapid/shallow breathing
what is the ANS inneration
determines the diameter of the airways (constriction and dilation)
what is the affect of the parasympathetic on the lungs
vagus nerve will cause constriction of the airways
irritants/inflammation can trigger
what is the sympathetic affect on the lungs
causes relaxation of the airways
- dilation occurs due to catecholamines
stress - b-agnoists
what is FiO2
% of oxygen they are getting in
what is the PaO2 within the pulmonary artery
40mmHg
what is the PaO2 within the pulmonary vein
100mmHg
what is ABG
arterial blood gas
what is the ABG a gold standard test for evaluating
acid-base balance
oxygenation
ventilation
what are indications for ABG
critically ill, respiratory condition, metabolic disorder
ICU, ED never done in Primary care
how is ABG obtained
radial arterial puncture - uncomfortable for patients
what does the ABG tell us
pH
PaO2/PO2
PaCO2/PCO2
HCO3 concentration
degree of excess or deficit of base in the blood
O2 Sat
What is an alternative to ABG
venous blood gas (VBG) - can assess oxygenation
provides venous pH and HCO3 concentrations
End-tidal CO2/Capnography - requires tight fitting mask or intubation
what does protein breakdown yield
acids
what is the normal pH of the blood
7.35 - 7.45
what does pH =
-log (H+)
HCO3- (mEq/L) / pCO2 (mmHg)
where is bicarbonate made
in the kidney to buffer acids -> more alkalotic
where is bicarbonate reabsobed
by the proximal tubule
why is pH important
metabolic functioning
protein structure
enzymatic functioning
cell wall integrity
…so many things
how does acidosis affect metabolism
hyperkalemia
how does alkalosis affect metabolism
decreased push of protons into the cell
this means that the calcium, mag, K are not getting pushed out of the cells so they can drop in ECF
how does acidosis affect the respiratory system
tachypnea
can drop CO2 to about 10 at lowest point
Right shift
how does alkalosis affect the respiratory system
low respiratory rate
left shift
how does acidosis affect cardiovascular system
decreased cardiac output
vasodilation
increase ectopic rhythms from unstable cellular function
hyperkalemia
how does alkalosis affect cardiovascular system
leads to excitability
ventricular tachyarrhythmias
SVT
hypokalemia
how quickly do the lungs react to bicarbonate levels
within minutes
how quickly do the kidneys react to bicarbonate
hours to days
what is ionic shifts
H+ is exchanged for K+ (and others) across cellular membranes
occurs within hours
what is an anion gap
AG = Na - (Cl + HCO3)
what are acid base disorders
respiratory acidosis
respiratory alkalosis
metabolic acidosis
metabolic alkalosis
what can cause respiratory acidosis
anything that impairs ventilation or oxygenation
asthma/COPD
obstruction
pneumonia (rare)
Head/chest trauma
respiratory depression (CNS lesions, drugs, sedation)
what causes respiratory alkalosis
think anything that causes hyperventilation
pain/anxiety
CNS disorders
salicylate (ASA)
liver disease
sepsis
what is respiratory acidosis hallmarked by
increase PaCO2
what is respiratory alkalosis hallmarked by
decreased PaCO2
what is metabolic acidosis
pH < 7.4 secondary to ‘metabolic’ disturbance
decreased acid excretion-> accumulation
increased acid load (ketones, lactate)
reduced level of base (HCO3)
what is metabolic alkalosis
pH > 7.4 secondary to metabolic distrubance
excess acid excretion
increased level of base (HCO3)
hallmark is increased serum levels of HCO3
What is the ROME criteria
Respiratory are Opposites, Metabolic is Equivalent
what is a common way to measure and monitor arterial oxygen saturation
pulse oximetry
ration of oxygenated hemoglobin to total hemoglobin
expressed as percentage
what are the different lung volume types
tidal volume
reserve volume (inspiratory, expiratory)
residual volume
what are the different lung capacity types
inspiratory, expiratory, functional residual, vital capacity, total lung capacity
what is the tidal volume
the amount of air that can be inhaled or exhaled in one respiratory cycle (normal breath)
will include volume to fill physiologic dead space
normal = 300-500mL
what is the minute ventilation
tidal volume (TV) x Respiratory Rate (RR)
what is inspiratory reserve volume
amount of air that can be forcibly inhaled after tidal volume (amount in a ‘deep breath’)
normal = 1900-3300 mL
what is expiratory reserve volume
amount of air that can be forcibly exhaled beyond tidal volume (amount in ‘full exhale’)
normal = 700-1200mL
what is residual volume
amount of air that remains in the lungs after full exhale
normal about 1200mL
what is inspiratory capacity
total inspiratory volume
inspiratory reserve + TV
what is total lung capacity
total volume of air the lungs can accommodate with maximal inspiration
Calculated (IRV + TV + ERV + RV)
normal about 4-6L
what is vital capacity
total volume exhaled after full inhalation 4800mL
TV is only about 10% of vital capacity (VC)
what is functional residual capacity (FRC)
air in the lung after a typical exhalation (non-forced)
what is a PFT
pulmonary function tests
start with spirometry
if abnormal - repeat after bronchodilator
what are PFTs utilized for
to diagnose restrictive and obstructive pulmonary disorders
