Anesthetic monitoring Flashcards
what should be monitored when a patient is under anesthesia?
monitor vital signs, reflexes, tones, and other indicators (life status, anesthetic depth status)
what does prolonged CRT mean?
prolonged (> 2 secs) may indicate hypotension, hypovolemia, hypothermia, vasodilation, vasoconstriction, cardiac failure, shock
what are ways to review oxygenation status?
mm color, RR, respiratory character, Vt, pulse oximetry, blood gas analysis
mm colors and meanings
pale= hypovolemia, hypotension, vasoconstriction, shock
cyanosis= hypoxemia
temp, vascular resistance, gum disease, and certain breeds (Chow Chow) may alter color
respiratory rate
can be monitored by watching chest movement, reservoir bag movement, and capnography
monitor respiratory character: effort required, relative length of inhalation and exhalation
gasping or labored breathing may require intervention
Vt or tidal volume
total volume inhaled in mL’s during normal breath
usually decreased under anesthesia
10-20 mL/kg
abnormal breathing patterns
abdominal breathing= expansion and contraction of abdomen during breathing
stridor= high pitched breathing noise (laryngeal obstruction)
stertor= low/deep pitched breathing noise (snoring)
pulse oximetry
estimates saturation of hemoglobin (So2)
expressed as %
gives pulse wave form (quality of pulse) noninvasive, portable, inexpensive
easy to use
how does the pulse oximeter work?
red and infrared-wavelength light is emitted by the probe and passes through/reflected off tissue bed
frequency of the light is read by the sensor and analyzed
machine determines oxygen saturation by calculating difference between levels of oxygenated and deoxygenated hemoglobin based on subtle differences in light absorption
what is the normal percentage of pulse oximetry?
> 95%
blood gas analysis
alternative way to monitor oxygenation, CO2, and acid-base status in blood
arterial sample is diagnostic for oxygenation
what are the ways to evaluate heart rate?
auscultation, digital palpation, esophageal stethoscope/doppler (long, thin, flexible catheter attached to an electrical amplifier or to a binaural stethoscope), doppler, EKG (used to detect arrythymias)
P wave
first little wave of pulse
SA node triggered causing atria depolarization
QRS complex
the spike down, up, down
caused by depolarization of the ventricles, triggers main pumping contractions
PR interval
flat line between P wave and QRS complex
caused by a delay of the AV node to allow ventricle filling
ST segment
flat line between QRS complex and T wave
caused by beginning of ventricle repolarization
T wave
little wave that comes after QRS complex
caused by ventricular repolarization
wave of depolarization traveling toward a positive electrode results in a ____ deflection in EKG trace
positive
wave of depolarization traveling away from a positive electrode results in a ____ deflection
negative
wave of repolarization traveling toward a positive electrode results in a _____ deflection
negative
sinus arrhythmia
3 waves close together with a large space between the next group of 3 waves
treat with lidocaine
sinus tachycardia
T wave goes down instead of up
VPC/PVC (ventricular premature contraction or premature ventricular contraction)
heart waves are more rounded and longer than the usual short waves/spikes up and down
ventricular fibrilation
rounded waves going up and down in no particular rhythm
need to shock/do CPR
what are the different types of AV heart blocks?
1st degree: longer PR interval
2nd degree: (2:1) skipped some QRS complexes and T waves
3rd degree: skipped QRS complexes/T waves and longer PR interval
BP
force exerted by flowing blood on arterial walls
used to monitor perfusion
things that have an effect on BP: HR, stroke volume, vascular resistance, arterial compliance, and blood volume
systolic BP
contraction of left ventricle
diastolic BP
pressure that remains in arteries when heart is resting between contractions
MAP
average pressure through cardiac cycle
common causes of hypotension
anesthetic agents, excessive anesthetic depth, vasodilation, blood loss, dehydration, cardiac arrhythmias, preexisting heart disease, PPV, gastric distention
how do you prevent hypotension?
avoid excess depth, provide adequate analgesia, use pre-med to decrease MAC, avoid drugs that decrease cardiac onset/induce bradycardia/cause vasodilation, administer IV fluids at sufficient rate, give vasopressors
pulse strength
rough indicator of BP
palpate peripheral arteries (lingual, femoral, dorsal pedal)
normal pulse should be strong and occur shortly after each heartbeat
anesthetics can decrease pulse strength
direct BP monitoring
arterial catheterization, pressure transducer
doppler or oscillometric BP
central venous pressure
capnography
measures CO2 in the gas that is breathed in and out by the patient and provides graph
what is CO2?
a heavy odorless colorless gas formed during respiration and by decomposition of organic substances
expired CO2
EtCO2
inspired CO2
InCO2
normal EtCO2
35-45 mmHg
normal InCO2
0 mmHg
why are capnographs helpful to use?
they are noninvasive, continuous, and practical
don’t need arterial catheterization
useful during anesthesia and CPR because it can be 1st indicator of death and also of good quality chest compressions
what does a capnograph monitor consist of?
a sensor and computerized monitor with a digital readout
sensor measures infrared light absorption which is directly proportional to CO2 level
what are the types of capnographs?
mainstream: sensor chamber is between ETT and breathing circuit = instant results
side-stream: sensor is in the monitor, air sample is pulled between the ETT and the breathing circuit = less dead space with delayed results
capnograph(y)
monitoring of the concentration of partial pressure of CO2 in respiratory gases
capnogram
waveform tracing produced by capnograph
hypercapnia/hypercarbia
excessive CO2 in the bloodstream
hypocapnia/hypocarbia
deficiency of CO2 in the bloodstream
respiratory acidosis
increased levels of CO2 in the blood due to not breathing enough
respiratory alkalosis
decreased levels of CO2 in the bloodstream due to breathing excessively
ventilation
ability for lungs to exchange gases
what does EtCO2 indicate?
ventilation and perfusion
perfusion
ability for blood to flow throughout the CV system
what is affected by abnormal ventilation or perfusion?
the EtCO2 value and waveform
what happens when a patient is hypoventilating/apneic?
will retain CO2 in the blood and makes them acidotic
what happens when a patient is hyperventilating?
will expel too much CO2 and makes them alkalotic
capnography phase 1
expiratory baseline
beginning of exhalation and corresponds to exhalation of CO2-free dead space gas from the larger conducting airways, CO2 value during this phase should be 0
capnography phase 2
expiratory upstroke
involves exhalation of mixed alveolar and decreased dead space gas which rapidly increases CO2 concentration
capnography phase 3
expiratory plateau
occurs when all the dead space gas has been exhaled resulting in exhalation of completely alveolar air
highest point of phase 3 corresponds with the actual EtCO2 value
the plateau has a slight positive slope because of the continuous diffusion of CO2 from the capillaries into the alveolar space
capnography phase 0
inspiratory downstroke
because of inhalation of CO2-free gas the CO2 concentration rapidly declines
what are the angles that are made between phase II/phase III and phase III/phase 0 on a capnograph called?
angle made by plane II and plane III is called alpha
angle made by plane III and plane 0 is called beta
the beta angle is the EtCO2 measurement
what is the “elephant” capnography abnormality?
characterized by a gradual increase. in baseline and EtCO2 that looks like a herd of elephants
caused by rebreathing of exhaled gases which makes the inspiratory phase not return to baseline
capnograph with little hump wave after at inspiration after phase 0 instead of a flat line
seen in a nonrebreathing system
during inspiration a small rebreathing wave can result from inhalation of CO2, the extent of rebreathing depends on fresh gas flow, Vt, and RR
capnograph with more visible upward sloping plateau instead of slight upward plateau
caused by a bronchospasm or another expiratory obstructive process that prevents complete alveolar emptying
capnograph with a small wave downwards in the middle of phase III
(like a hole in the ground)
capnogram of a patient emerging from neuromuscular blockade and demonstrating a curare cleft
capnograph with normal shape but decreased plateau height each time
can result from hypovolemia, hyperventilation, hypothermia, and increased dead space ventilation
capnograph hole in phase 0
dilution of EtCO2 by fresh gas flow which produces a terminal dip in plateau
capnograph with squiggles going downwards during phase 0
oscillations during inspiratory phase
results from cardiac pulsations or fluttering of the inspiratory valve in a rebreathing circuit
capnograph with curved plateau
abnormal plateau and inspiratory downstroke
caused by ETT cuff leakage
how is body temperature regulated?
regulated by a physiological process called thermoregulation
regulated by hypothalmus
how can body temperature be taken during anesthesia?
esophageal or rectal
when is body temperature loss the greatest?
during the first 20 minutes of the surgery
because of clipping, prepping, starting room temp fluids, starting cold O2
what is hypothermia caused by?
evaporation, conduction, vasodilation, decreased metabolic rate, lack of body fat, room temperature fluids, respiration
what effects does hypothermia have on the body?
increases risk of infection and slows metabolism
when can hyperthermia occur?
if patient has head trauma, excessive heat, or if patient is allergic to anesthetic agents
what devices can be used to maintain body temperature?
bear hugger, warm water blankets, warmies, fluid warmers, warm blankets, heated tables, heating lamps
