respiratory monitors and equipment Flashcards
which conditions are most likely associated with this aw pressure wave form
bronchospasm
kinked ETT
aspiration of foreign body
(elevated peak pressure with normal plateau pressure. reduction in dynamic compliance with increase in aw resistance)
define dynamic compliance
function of aw resistance* (different from static) and tendency of lung/chest to collapse
PIP is affected by
aw resistance as well as chest/lung compliance (Pelastic)
define plateau pressure
pressure in small airways and alveoli after target volume is delivered
- since there is not air flow during this, airway resistance does not affect plateau pressure
-reflects elastic recoil of lungs during inspiratory pause
barotrauma is a risk when plateau pressure exceeds
35cmH2O
complications of elevated plateau pressure include
VALI, PTX, pneumomediastinum, SQ emphysema
if barotrauma exists, you should reduce plateau pressure by reducing
Vt, inspiratory flow, and PEEP
in the adult, normal static compliance is
35-100mL/cmH2O
in the child, normal dynamic compliance is
> 15mL/cmH2O
why would this occur
resistance has increased (reduction in dynamic compliance) or inspiratory flow has increased
why would this occur
total compliance has decreased (Pelastic has increased)
or Vt has increased
examples of increased resistance
kinked ETT
ETT cuff herniation
bronchospasm
bronchial secretions
compression of aw
foreign body aspiration
examples of decreased compliance
endobronchial intubation
pulmonary edema
pleural effusion
tension pneumo
atelectasis
chest wall edema
abdominal insufflation
ascites
trendelenburg
inadequate muscle relaxation
ID parts of the capnograph and what they represent
you measure end tidal at D
where is alpha angle measured, what is the normal degrees, and what can increase it
point C, between 100-110 degrees usually
-increased alpha angle signifies expiratory air flow obstruction, such as COPD, bronchospasm, or a kinked ETT
where is beta angle measured, what is the normal degrees, and what can increase it
point D, creates a 90 degree angle
-increased in some (but not all) instances of rebreathing
what kind of O2 analyzer is this and key facts
main stream (in line)
-faster response time, doesn’t require water trap or pumping mechanism
-increases apparatus dead space and adds extra weight
what kind of O2 analyzer is this and key facts
side stream (diverting)
-pump continually aspirating CO2 to be analyzed so has a lag time
-requires water trap to prevent contamination of device
define the problem with this wave form and common causes
air flow obstruction (prolonged up stroke, increased alpha angle)
COPD, bronchospasm, kinked ETT
define the problem with this wave form and common causes
no problem, just cardiac oscillations. common in kids.
define the problem with this wave form and common causes
curare cleft, happens during spontaneously initiated breaths
-suggests lack of muscle relaxant reversal if during spontaneous ventilation
define the problem with this wave form and common causes
low EtCO2 caused by hyperventilation, decreased CO2 production, or increased dead space
ex) hyperventilation: light anesthesia, metabolic acidosis
decreased CO2 production: hypothermia
increased dead space: HoTN, PE
define the problem with this wave form and common causes
increased EtCO2 with normal plateau
increased CO2 production (MH, sepsis, fever, hyperthyroidism) or decreased alveolar ventilation (hypoventilation, narcotics)
define the problem with this wave form and common causes
rebreathing
ex) exhausted absorbent, incompetent expiratory valve, hole in inner tube of bain system, inadequate FGF with mapleson, rebreathing under drapes of patient who is not intubated
define the problem with this wave form and common causes
incompetent inspiratory valve (may or may not reach zero based on FGF)
widened beta angle
define the problem with this wave form and common causes
leak in sample line during PPV
(PP during inspiration pushes CO2 rich gas into sample line hence the increase at the end)
not seen with spontaneous ventilation because there is no positive pressure
may also occur in obese and pregnant patients
define the problem with this wave form and common causes
biphasic expiratory plateaus
-can occur after single lung transplant (alveolar gas from transplanted lung and diseased lung have different time constants. first peak is alveolar gas from transplanted lung.)
-also can be from severe kyphoscoliosis
causes of increased EtCO2 r/t increased CO2 production and delivery to the lungs include
increased BMR (increased VO2)
MH
thyrotoxicosis
fever
sepsis
seizures
laparoscopy
tourniquet or vascular clamp removal
sodium bicarb admin
shivering
increased muscle tone (after NMB reversal)
meds SE
causes of increased EtCO2 r/t decreased alveolar ventilation
hypoventilation
CNS depression
residual NMB
COPD
high spinal
neuromuscular disease
metabolic alkalosis
med SE
causes of increased EtCO2 r/t equipment malfunction
rebreathing
CO2 absorbent exhaustion
unidirectional valve malfunction
leak in breathing circuit
increased apparatus dead space
causes of decreased EtCO2 r/t decreased CO2 production and delivery to the lungs
decreased BMR (VO2)
increased anesthetic depth
hypothermia
decreased p.BF
decreased CO
HoTN
PE
VQ mismatch
med SE
pain/anxiety (if breathing spontaneously)
causes of decreased EtCO2 r/t increased alveolar ventilation (4)
hyperventilation
inadequate anesthesia
metabolic acidosis
med SE
causes of decreased EtCO2 r/t equipment malfunction
ventilator disconnect
esophageal intubation
poor leak seal with ETT or LMA
sample line leak
airway obstruction
apnea
which kind of light on pulse ox absorbs which kind of HGB (oxyHGB v deoxyHGB)
red light (660nm) preferentially absorbs deoxyHGB
near infrared light (940nm) preferentially absorbs oxyHGB
SpO2 =
oxygenated HGB/(oxygenated HGB + deoxygenated HGB) x 100%
most to least responsive places to measure SpO2
fast: ear, nose, tongue, esophagus, forehead
middle: finger
slow: toe
if in trendelenburg, can be falsely elevated in forehead and esophagus d/t engorged veins
the pulse ox is a noninvasive monitor of
HGB sat, HR, fluid responsiveness, PPV
other examples of how the pulse ox can monitor for perfusion
placement of toe monitor for perfusion in lithotomy position
limb perfusion following a fracture
brachial artery compression during shoulder arthroscopy
why is a pulse ox not a monitor of anemia
percentage of HGB bound with O2
-does not quantify amount or account for O2 dissolved blood
pulse oximetry and metHGB
-absorbs 660 and 940 equally
-falsely under estimates SpO2 if O2 sat >85%
-falsely over estimates SpO2 if O2 sat <85%
pulse oximetry and carboxyHGB
-absorbs 660nm to the same degree as oxyHGB
-reads sum of CO HGB and oxyHGB aka over estimates SpO2
factors that do NOT affect pulse ox
jaundice
HGB s
HGB F
fluorescein
polycythemia
acrylic finger nails
what is the most common method of measuring exhaled gases inside the breathing circuit
infrared absorption
does O2 get measured via infrared absorption
no, has to be measured via electrochemical analysis (galvanic cell or clark electrode)
define mass spectrometry
bombards gas sample using ion fragments, because all particles become charged, they separate and are ID’d based on their mass.
-large and may be utilized for more than one patient at a time
raman scatter spectrometry
-uses high power argon laser to produce photons, which in turn collide with gas molecules.
define piezoelectric crystals
-can detect inspired, expired, and breath to breath changes of particular gas by incorporating lipid layer on crystal.
-cannot ID multiple gases at once though so cant use in clinical setting
most common cause of reduction in EtCO2
increased dead space (so like hemorrhage would be the right answer)
