Monitoring Final Flashcards
2 Basic Modes of US for vascular access
Doppler and B-mode
Doppler US
audible sound
- arteries and veins sound different
B-Mode US
2D mode
Generates a 2D picture in a gray scale that is applied based on the amplitude of the signal
- B stands for brightness
B-Mode US appearance
fluid filled = black or dark grey
soft tissue (muscle) = gray
Solid structures
Technical Tricks for IV access
T-berg and valsalva manuever
Controls to know on US machine
- gain adjust
- depth
- freeze
- contrast/brightness
4 manuevers for a good US image
- pressure
- alignment
- rotation
- tilting
Color Doppler
represent the direction of low relative to transducer
- Red: flow towards transducer
- Red does not always mean artery
When is a provider considered competent in CVC placement
after 50 times
US guidance for regional usually uses what probes?
linear probes and dynamic (B-mode) setting
Different frequencies for regional anesthesia
Higher frequency for superficial (upper extremity) blocks
Lower frequency needed for deeper blocks (infraclavicular, femoral)
CFNB
continuous femoral nerve block
US vs. nerve stimulator
US has decreased time to placement and no conversion to general anesthesia
What does an implantable pacemaker treat?
bradycardia and conduction abnormalities
What does AICD treat?
SVT and fibrillation
What battery is commonly used in a pacemaker?
lithium-iodide
How long does a pacemaker/AICD usually last?
5-8 years
- output voltage decreases gradually
- sudden battery failure unlikely
Pacemaker lead system
- endocardial leads placed via central access
- fix on the endocardium
Endocardial Leads
active fixation: metal scews
passive fixation: rubber fins or tines
Epicardial Leads
screw-in or sew-on
Polarity of pacing leads
unipolar - highest reliability
bipolar - improved rejection for better sensing
multipolar - special purpose leads
Types of lead tip of pacing leads
- steroid eluting
- non-steroid eluting
- carbon
Synchronous Pacemaker (basics)
- Demand mode
- Sensing circuit searches for intrinsic depolarization potential
- If absent, a pacing response is generated
- Can mimic intrinsic electrical activity pattern of the heart
Anti-tachycardic functions are only used in which type of pacer?
AICDs
1 in pacemaker classification
What does it pace?
V – Ventricle
A – Atrial
D – Both
0 – None
2 in pacemaker classification
What does it sense?
V– Ventricle
A – Atrial
D – Both
0 – None
3 in pacemaker classification
How does it respond?
I – Inhibited
T – Triggered
D – Inhibited & Triggered
0 – None
Inherent rate of SA node
60-100 bpm
inherent rate of AV node
40-60 bpm
Inherent rate of His and Purkinje
20-40 bpm
(6) Absolute indications for a Pacemaker
- sick sinus syndrome
- symptomatic sinus bradycardia
- tachy-brady syndrome
- a-fib with slow ventricular response
- 3rd degree heart block
- chronotropic incompetence
Chronotropic incompetence
inability to increase heart rate to match exercise
Programability Function “R”
rate responsive
device is capable of a rate responsive function
Programability Function “C”
Communicating
capable of transmitting or receiving data
Programability Function “M”
multi-programmable
device can be programmed in more than 3 parameters
rate, sensing, output, refractory periods, mode hysteresis
Programability Function “P”
simple programmable
limited to 3 or fewer programmable parameters
Programability Function “O”
None
not programmable
Most bradycardia devices are ____
O
Most AICDs are ____
D
AOO
fixed atrial pacing
VOO
fixed ventricular pacing
DOO
fixed AV sequential pacing
Asynchronous Modes
during application of a magnet
- does not mean you are turning off pacemaker
- AOO, VOO, DOO
VVI
single chamber pacing
- if native activity is sensed, pacemaker will not fire (inhibit)
- Also has a clock to prevent firing during refractory period
DDD
paces atria and ventricle
- senses atria and ventricle
- atrial triggered and ventricular inhibited
- EKG shows 2 spikes
what does AICD stand for?
Automatic Implantable Cardio-Defibrillator
What can and AICD do?
- antitachycardia pacing
- cardioversion
- defibrillation
- bradycardia pacing
Joules applied to biphasic vs. monophasic
biphasic - 150J
monophasic - 300J
Anti-Tachycardia Pacing (ATP)
overdrive pacing in an attempt to terminate ventricular tachycardias
- fires during refractory period
Magnets and pacemakers
closes an internal reed switch
- causes sensing to be inhibited
- asynchronous mode
Anesthesia for Patient with Pacemaker
- know what type and what the magnet does
- set to fixed rate pacing unless bipolar
- continuous ECG and peripheral pulse
- pulse ox with plethysmography to see mechanical heart output
- defibrillator and crash cart available
- external pacer available
- external converter magnet available
Essential information to ask CIED team
- indication for device placement
- current programming
- is the patient pacemaker-dependent?
- device response to magnet
- perioperative recommendation/prescription
How do you know if a magnet is working on a pacer?
if it goes to 60bpm and stays there
Bipolar vs Electrocautery and pacemakers
Bipolar - OK
Electrocautery may interfere with pacer
Cardiac arrest with AICD
start CPR and defibrillate immediately
IABP
Intra-Aortic Balloon Counterpulsation
Intra-Aortic Balloon Counterpulsation
used to reduce left ventricular systolic work, LVED pressure, and wall tension
Benefits of IABP
- decreases O2 consumption
- increases CO, perfusion
- increases pressure to coronary arteries
Where is an IABP placed through and position?
placed through femoral artery into the descending aorta
tip should be 1-2cm below the origin of the left subclavian artery and above the renal arteries
Balloon volume in IABP
30 - 50 mL
Drive gas in IABP
helium or carbon dioxide
Hemodynamic affects of IABP
- increase coronary perfusion
\+ increase diastolic BP
\+ decrease atrial pressure
- decrease afterload on left ventricle
\+ decrease aortic systolic pressure
- decreases LVEDV and LVEDPIABP balloon inflation
triggered to inflate immediately after aortic valve closure
- augments diastolic coronary perfusion pressure
IABP balloon deflation
triggered to deflate with opening of the aortic valve
- reduce left ventricular work
- creates a “potential space” in the aorta
+ reduces aortic volume and pressure
Indications for IABP
- cardiac failure after surgery
- refractory angina
- cardiogenic shock
- mitral regurgitation
- perioperative treatment of complications due to MI
- failed PTCA
- bridge to cardiac transplantation
Contraindications for IABP
- severe aortic insufficiency
- aortic aneurysm
- aortic dissection
- limb ischemia
- thromboembolism
CPB
cardio pulmonary bypass
(3) Functions of CPB
- oxygenation of venous blood
- elimination of CO2
- maintenance of system perfusion
main components of CPB
- blood reservoir
- oxygenators and gas exchangers
- pumps
- heat exchangers
- filters
- cardioplegia system
3 processes in urine formation
- glomerular filtration
- tubular reabsorption
- tubular secretion
Normal urine output
> 1 mL/kg/hr
- daily output of 400-500 is required to excrete nitrogenous wastes
most likely cause of oliguria
decreased renal perfusion
- hypotension
- hypovolemia
- decreased CO
red urine
hemoglobinuria, myoglobinuria, hematuria, beets, rifampin
orange urine
bilirubin or pyridium
brown urine
bilirubin or methemoglobin
black urine
melanin, hemoglobinuria, and homogentistic acid
Blue urine
amitriptyline and methylene blue
white urine
chyluria
magnetic strength of MRI
1.5 to 4 Tesla
60,000x Earth’s field
How are MRI magnets cooled
liquid helium and nitrogen
ferromagnetic
materials that form permanent magnets or are attracted to magnets
Paramagnetic
only attracted when in the presence of an externally applied magnetic field
diamagnetic
materials repelled by magnetic fields
Gauss Line
5 gauss
- ‘safe’ level of magnetic exposure
Magnetic Force in MRI
Attractive Force = M * (1/D)^2
M = mass D = distance
Quench
(emergency stop)
destruction of superconducting state and a change to increased magnet resistance
Where is the superimposed potential greatest in ECG?
ST-segment and the T waves of leads I, II, V1, and V2
which vectors maximize QRS and minimize artifact in an ECG
V5 and V6
temperature monitoring in MRI
liquid crystal strips
Medication patches that need to be removed for MRI
- Androderm
- transderm-Nitro and Deponit
- Habitrol, Nicoderm, and Nicotrol
- Scopolamine
- Catapres-tts (clonidine)
Blood in 4x4
10 mL
blood in ray-techs
10-20mL
blood in lap sponges
100 mL
Primary physiologic response to blood loss
- Increased HR
- Hyperventilation
- Vasoconstriction
- Increased RV filling
Secondary physiologic response to blood loss
BP increase by hormones and catecholamines
Tertiary physiologic response to blood loss
redistribution of water from extravascular to intravascular space
Intrinsic coagulation factors
8, 9, 11, 12
What measures intrinsic coagulation
aPTT and ACT
- Heparin
What measures extrinsic coagulation
PT and INR
- coumadin
Common coagulation can be measured by ____
PT and INR
Extrinsic coagulation factors
3 and 7
Which coagulation pathway releases tissue factors
Extrinsic
Normal platelet value
150k - 400k /mm^3
Thrombocytopenia
Thrombocytosis
> 400,000 platelets
Petechiae
small red or purple spots caused by bleeding into the skin
- Thrombocytopenia
DIC
Disseminated Intravascular Coagulation
- accelerated platelet consumption
- caused by sepsis, trauma, burn…
- high levels of FSP
ACT
Activated Clotting Time
- measures the amount of time required for whole blood to clot in a test tube
- monitors Heparin
Normal ACT
70-180 sec
CPB > 400 seconds
2 Types of ACT
- Hemochron
+ uses a magnet - HemoTec
+ photodetector
PTT
Partial Thromboplastin Time
- measures the clotting time via factor 7, 9, 11, and 12
- intrinsic (Heparin)
Prolonged PTT
- cirrhosis
- DIC
- hemophilia
- malabsorption
- von Willebrand’s disease
lupus
Prothrombin Time (PT)
measures 7 (extrinsic) and common
- normal 10-14 seconds
Increased PT times
- bile duct obstruction
- cirrhosis or hepatitis
- vitamin K deficiency
- Coumadin therapy
INR
International Normalized Ratio
- mathematical calculation that corrects for PT variability due to sensitivities (ISI) of the thromboplastin agents
ISI
International Sensitivity Index
Normal INR
- 0
- 2-3 is recommended for prophylaxis
TEG
Thromboelastogram
- measure of the time it takes for a blood clot to form, consolidate, and lyse
- R, k, alpha angle, MA, and MA60
TEG variables
R - period of time k - dynamics of clot formation alpha angle - acceleration of fibrin build up and cross-linking MA - maximum amplitude MA60 - stability of the clot
Low MA on TEG
platelets indicated
- MA is a function of platelet count, function, and fibrinogen level
High MA60 on TEG
antifibrinolytics indicated
Prolonged R on TEG
FFP indicated
Absolute Blood Loss (ABL)
ABL = EBV * [(HCTi - HCTf)/(HCTi)]
Estimated blood volumes
Adult male - 70 mL/kg
thin female - 65
Muscular - 75
Obese - 60
Estimate blood volumes in pediatrics
Premie 90-100 ml/kg
Term 80-90
Type and Screen
Recipient’s blood has been typed for A, B, and Rh antigens and screened for common antibodies
Type and Cross
Recipient’s blood is incubated with the donor blood product
Type A blood
Contains an A antigen
Anti-B antibodies present
Type O blood
No antigens present
Both A and B antibodies
PRBC
Packed Red Blood Cells
- 1 unit contains 250-300mL with 70-80% hematocrit
- Hemoglobin increases 1 g/dL
- Hct will increase by 3%
Platelets
- mostly used in CPB
- 6 units will increase platelet 25,000
- DO NOT warm
- use filter
Fresh Frozen Plasma
Fluid portion obtained form a single unit of whole blood
- indicated when PT, PTT, or both are at least 1.5 times longer than normal
Cryoprecipitate
Fraction of plasma that precipitates when FFP is thawed
- 200mg fibrinogen and 100 units of Factor VIII
- used in hemophilia A or hypofibrinogenemia
Incidence of Hepatitis B in blood transfusion
1 in 205,000
Incidence of Hepatitis C in blood transfusion
1 in 1.9 million
Incidence of HIV in blood transfusion
1 in 2.1 million
POC
Point of Care
Are creatinine and hematocrit POC tests?
No
POC hemoglobin
photometer uses 570 and 880 wavelength
- erythrocytes are trasformed into methemoglobin and then into azidemethemoglobin
- range 0-25.6 g/dL
Hemocue
Detects anemia
- 75% sensitivity, 100% specificity
missed event likely to occur when anemic
Main POCTs
- blood gas analysis
- glucose
- hemoglobin
- ACT
