Monitors – Chemistry – Flashcards

Unlock all answers in this set

Unlock answers
question
Normal values for cardiac output, cardiac index, and pulmonary artery pressures.
answer
CO:4-7L/min
CI: 2.5-4L/min/m2 of BSA
PAP: 30s/10d with mean <20
question
What is normal CVP,right ventricle pressure,PAW?
answer
CVP: 0-5
RVP: 30/5
PAW/PAOP: <20
question
Name normal left atrial, left ventricle, and aortic pressures?
answer
LAP: <12m
LVP: 140/12
Aorta: S<140, D<90, M: 70-90
question
Name equation for MAP
answer
(systolic-diastolic)/3 + diastolic
question
Normal ICP values
answer
Normally 7-18 cm water, measured in lumbar area
In lateral recumbent 13 cm water
If sitting 37-55 cm water
question
Law of La Place
answer
sphere: P=2t/r
cylinder:P(2RL) = T(2L) or T = PR
• Where
o P = pressure at outlet
o T = tension of wall
o R = radius of wall
• Note
o If the wall is stationary, the outward and inward forces
across it are equal.
o Cross-sectional area: A = 2RL
o Distending force (outward pressure times area):
PA = P(2RL)
o Restraining pressure acting inward (tension times
length): T(2L)
question
Describe BP variance with respiration
answer
Inhalation causes a decrease intrathoracic pressure that aids venour return. Exhalation does the opposite.
question
Describe BP variance under mechanical ventilation.
answer
PPV= increased intrathoracic pressure, decreased venous return, especiallly during inspiration. Decreased art. line amplitude under PPV= pt is dry.
question
SVR equation
answer
SVR=[(MAP-CVP)x80]/CO
nomal is 1500-1900 dynes/sec/cm-5
As resistance increases, flow (perfusion) decreases
question
Increased SVR
answer
Adaptive in low volume states
Maladaptive post MI where it decreases tissue perfusion and increases cardiac afterload
Also seen during SNS response, increased catecholamine release
question
Decreased CO
answer
Caused primarily by decreased venous return in a variety of conditions
question
Causes of increased CO
answer
Septic shock (early), nipride, increased metabolism, etc. Will have a higher mv02
question
Hemodynamic trends in septic shock
answer
decreased PCW, MAP, SVR. Increased CI.
question
Hemodynamic trends in cardiogenic shock.
answer
Decreased MAP, CI. Increased PCW and SVR
question
Hemodynamic trends in hemhorragic shock
answer
Decreased MAP, CI, PCW. Increased SVR.
question
Modified Allen's Test
answer
Shows Ulnar nerve patency. To be done before art line insertion
question
List circumstances in which PWP may not equal LVEDP
answer
Stiff and noncompliant LV, mitral valve disease, LA hypertrophy or pulmonary disease (normal PWP with elevated LAP)
question
List circumstances in which CVP will not reflect accurate LVEDP
answer
pulmonic and tricuspid valve problems. RAP is influenced by volume, venous tone, increased PVR
question
CVP reflects...
answer
RAP, RVEDV, preload,
question
RAP reflects...
answer
cardiac function, venous return to the heart.
question
4 determinants of cardiac function
answer
preload, afterload, HR, contractility
question
Name components of CVP waveform
answer
a wave:right atrial contraction, p wave
c wave: tricuspid valve bulge during early RV contraction. QRS
x descent: downward movement of RV during contraction. Before T wave
v wave:RA full and tricuspid is bulging. As T wave is ending
y descent: Tricuspid open, RV diastole, before p wave.
question
Pathologic CVP waveforms
answer
Afib: no A waves
AV dissociation: Cannon A waves. Increased in size
Tricuspid regurg: looks like artline waveform. c wave and x descent replaced by regurg wave. False high mean, look at pressures between regurg waves
Tamponade: all pressures elevated, y descent small or gone
question
Contraindications to SWAN
answer
relative: WPW, Ebstein's malformations, L BBB, left fascicular block
question
Instances where PCWP overestimates LVEDP
answer
chronic mitral stenosis, PEEP, LA myxoma, pulmonary HTN
question
Instances where PAWP underestimates LVEDP
answer
Things that increase LV pressure: stiff LV, LVED>25 mm Hg, Aortic Insufficiency
question
Relationship between PCWP and PAEDV
answer
In absence of PVR, difference is 1-4 mm Hg
question
Determinents of preload
answer
1. atrial pressure (venous pressure and return)
2. HR
3. ventricular distensibility (compliance)
question
Depolarizing neuromuscular blockers
answer
Succ. Ach receptor agonist. Metabolized by pseudocholinesterase
question
Nondepolarizing neuromuscular blockers
answer
Ach competative antagonists. No depolarization.Reversal of their blockade depends on redistribution, gradual metabolism, excretion, or administration
of specific reversal agents (cholinesterase inhibitors) that inhibit acetylcholinesterase enzyme activity.
question
TOF
answer
Train of four is four supramaximal stimuli every 0.5 sec (2 Hz).
T4 is lost at 80% receptor occupancy, T3 at 85%, T2 at 90%, T1 at 95%
question
Phase I Block
answer
A phase I block (depolarizing blockade-Succinylcholine) does NOT exhibit fade during train of four. If enough Succinylcholine is
given, however, you can witness a phase 2 blockade. This usually occurs with repeated dosing and succinylcholine infusions.
question
Phase II BLock
answer
The occurrence of fade, a gradual lessening of evoked response, is
characteristic of nondepolarizing blockade. This is a phase II block.
question
Tetanic Stimulation
answer
Characterized by:
o Fade and post-tetanic facilitation (NDMR and phase II depolarizing block) or
o Diminished height from control without fade or PTF (depolarizing block).
• Disadvantages: It is painful and may produce lasting antagonism of block during recovery. It may also hasten onset by
increasing blood flow to the limb.
question
Post-Tetanic Count
answer
Post-tetanic count (PTC) - Apply tetanus at 50 Hz x 5 sec, wait 3 sec, then begin single twitch at 1 Hz.
• Number of PTCs correlates inversely with time to recovery of a deep block.
question
Double Burst Stimulation
answer
This is a mode consisting of two short bursts of 50 Hz tetanic stimulation separated by 750 msec.
• The aim is to allow tactile detection of small amounts of residual blockade under clinical conditions (more sensitive than TOF in
detecting residual paralysis).
question
Extubation parameter and associated NIFs
answer
Parameter Negative Inspiratory Pressure (cm H2O)
Control -90
Head lift 5 sec -53
Effective swallow -43
Patent airway with jaw lift -39
question
Evoked Potentials
answer
Can be sensory, motor, visual or auditory
Signals are produced as a nervous system response to stimuli, and altered signals can indicate dysfunction
Latency – time between the stimulus and potential
Amplitude – intensity or height of stimulus
question
Somatosensory Evoked Potentials (SSEP)
answer
Monitor the integrity of the sensory spinal cord (dorsal columns)
Can warn against spinal cord ischemia (posterior spinal arteries)
Technology is square-wave signals with sensory input, transfer to sensory (posterior) cord, then to the
thalamus and eventually the sensorimotor cortex
Volatile anesthetics decrease amplitude and increase latency of SSEPs. Use about 0.5 MAC of a volatile
agent and no greater than 50-60% N20
question
BIS monitor
answer
(Bispectral) monitor is used to measure depth of anesthesia.
• Data measured by EEG (electroencephalography) are taken through a number of steps to calculate a single number that
correlates with depth of anesthesia and hypnosis.
• BIS monitoring may reduce patient awareness and resource utilization in terms of drugs. It may also help facilitate a faster wakeup
time. Many of the initial studies were observational in nature and not randomized, prospective trials.
question
BIS Scale
answer
100 – awake
90-70 light/moderate sedation
70-60 deep sedation (low probability of recall)
60-40 general anesthesia
40-10 deep hypnotic state
10-0 flat EEG
question
Sudden increase in BIS
answer
Increased stimulation
Decreased anesthetic level
Vaporizer malfunction
Movement
Bair Hugger interference
question
Sudden decrease in BIS
answer
Decrease in surgical stimulation
Hypothermia
Lead placement
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New