Principles of Anesthesia II Unit I Flashcards
Lesions located where are rarely diagnosed/picked up on physical exam?
Mediastinum, interstitium and in the center of the lung
What is the relationship of acute vs chronic illness to the effectiveness of a physical exam vs CXR?
Physical exam is good for acute illness, CXR is better for chronic illness
What is under vs overexposure in an xray?
Over = the film is very dark
Under = the film is very bright
If the film is overexposed, what structures are easier to identify?
The T-spine, mediastinal structures and retrocardiac structures
Small nodules and fine structure cannot be seen if the film is overexposed
If the film is underexposed, what structures are easier to identify?
The small pulmonary blood vessels are more prominent
The downside here is d/t the underexposure it may give the appearance of there being infiltrates when none are present
Excessive breast tissue can cause what problem during a CXR?
The breast tissue absorbs some of the x-ray beam causing underexposure
What is the interpretative difference of a PA vs AP x-ray?
The heart will be magnified on an AP projection
This occurs because the heart is farther from the film and the x-ray beam diverges as it goes farther from the tube
When is PA projection of an x-ray commonly done? AP?
PA = generally done on ambulatory patients standing up
AP = on patients lying down, what we commonly did in the ICU
Why do we instruct patients to inspire for a CXR?
To push the liver and abdominal contents down. If not done, the pulmonary vessels can become crowded and the heart will appear larger
What do you need to be aware of if the domes of the diaphragm are at the seventh posterior ribs on x-ray?
The chest should be considered hypo-inflated and the diagnosis of basilar PNA or cardiomegaly should be done with extreme care
What are the 2 acronyms given to help standardize how you read a CXR?
ATMIB and Are There Many Lung Lesions
Both guide you to go; Abdomen first, then thorax, mediastinum, the individual lungs, then both lungs
On a CXR, how many anterior ribs are visible? Posterior?
A = 10
P = 6
What is the order, per lecture, to systematically read a CXR?
Start with the bony framework, then evaluate soft tissues, then the lung fields/Hila, diaphragm and pleural spaces, mediastinum and heart then the abdomen/neck
What structures are you examining when you inspect the bony framework?
You should be able to count and number the ribs, inspect the capulae, humeri and shoulders, and clavicles, and see the diaphragms overlying the posterior aspects of the 10th or 11th ribs (in a normal adult)> The spine and sternum are generally difficult to visualize in detail on standard PA films due to overlying shadows.
What are the soft tissues you are examining on CXR?
Breast shadows, supraclavicular areas and tissues along the sides of the chest
What creates the hilum (lung root) on a CXR?
The shadow of the pulmonary artery and vein that are adjacent to the heart shadow
What borders the right heart/mediastinal border? Left?
Right = IVC, RA, ascending aorta and SVC
Left = LV, LA, pulmonary artery, aortic arch and subclavian artery/vein
What are the 3 main pitfalls to x-ray interpretation?
Poor inspiration, over/under penetration and rotation
Which view of the lungs has extensive overlap?
The PA view
Which lung has more lobes?
R = 3 lobes
L = 2 lobes
The RUL is adjacent to what ribs?
The first 3 - 5 ribs posteriorly, anteriorly, it can extend as far as the 4th rib (more obvious on a lateral view)
The RLL is adjacent to what internal structures on x-ray?
The 6th thoracic vertebral body and extends to the diaphragm
What do the fissures in the R. Lung seperate?
Minor fissure (horizontal) separates the the RUL and the RML, the major fissure (oblique) separates the RLL from the others
Why are fissures not a reliable marker to use when examining a CXR?
They are not always easily identifiable and in some people they may not be completely formed or may even be completely absent on CXR
What areas are you examining with a lateral view?
Oblique fissure, horizontal fissure, thoracic spine, retrocardiac space and retrosternal space
What structures can you identify with a PA view?
Aortic arch
Pulmonary trunk
Left atrial appendage
Left ventricle
Right ventricle
Superior vena cava
Right hemidiaphragm
Left hemidiaphragm
Horizontal fissure
What is the silhouette sign?
Something is coming into contact with the border of the heart/aorta which obscures the normal border
What is the air bronchogram sign?
We can visualize the bronchi now (normally it is obscured by alveoli) which generally indicates some sort of consolidation (this consolidation of non-air material allows us to see the bronchi)
Most disease states replace _____ with a pathological process that creates the visual change on xray?
Air
A consolidation radiologically transcribes to what?
A density corresponding to a segment or lobe, air bronchogram and no significant loss of lung volume
What are the radiologic criteria for absorptive atelectasis?
- A density corresponding to a segment or lobe
- significant signs of loss of volume
- compensatory hyperinflation of normal lung(s)
What are the steps in evaluating an abnormality on CXR?
- Identification of abnormal shadows
- Localization of lesion
- Identification of pathological process
- Identification of etiology
- Confirmation of clinical suspension
Where should a CVC tip lie?
lie between the most proximal venous valves of the subclavian or jugular veins and the right atrium
The loss of what generally indicates a pleural effusion/accumulation of fluid outside the lung?
Loss of the costo-phrenic angle
How can you differentiate RLL vs RML lobe PNA on CXR?
They occupy almost the same position on an CXR, the easy way to identify the difference is RLL PNA will occupy most/all of the costo-phrenic angle, RML should leave that angle intact
What is a Gohn complex?
A lesion caused by TB that consists of a calcified focus of infection and an associated lymph node
What type of radiation comes from the motion of atoms and combine electricity and magnetism?
Electromagnetic
What type of radiation only travels through substances?
Mechanical
What type of radiation is the result of unstable atomic nuclei?
Nuclear
What type of radiation is composed of electrons only and is frequently emitted from the sun?
Cosmic (beta) waves
What type of radiation does a CXR utilize?
Electromagnetic
What category of radiation does not knock off electrons, doesn’t break molecular bonds and is only harmful from it’s ability to produce heat?
Non-ionizing
What process creates ionizing radiation?
Some stimulus (the exact stimulus is not important for this class) causes a particle to lose an electron, as the ion is created energy/radiation is produced
What category of radiation are you most likely to encounter in patient care areas?
Ionizing
non-ionizing dominates the break room though
Of the EMS spectrum, what rays are not part of the visible spectrum?
Radio waves and gamma rays
X-rays are most similar to what other ray?
Light rays
both are electromagnetic energy and carried by photons
What is the relationship of wavelength to energy of a ray?
As wavelength shortens, energy drastically increases
Describe how light is emitted (same process as creating a photon)?
An external stimulus causes an electron to become excited and jump to a higher orbital. This state is energetically unfavorable; and so the electron will eventually go back to a lower energy orbital. When this occurs, energy is released as a photon
What type of tissue is more likely to be made of small atoms? Large atoms?
Small = soft tissue
Large = bones
Why are bones bright on an x-ray?
Because they are larger atoms they absorb more photons making them appear brighter. Smaller atoms, like soft tissue, absorb less making them grey. Since air has very little to no capability to absorb photons the pulmonary space has a tendency to appear black
Describe the basics of how an x-ray machine works
A filament in a cathode heats up, this energy causes electrons to leave the filament. An anode made of tungsten is positively charged and attracts the photons across the tube. As the photons leave this tube, they hit tissues and reflect to create the image.
What environmental factor can alter a CXR’s appearance?
Ambient light
What is the basic difference between a CT and a CXR?
Both use x-rays to create an image, a CT however uses x-rays along with computer processing to create a 3D image
What is a non-image related use for medical x-rays?
Radiation therapy for cancer
What s/e of radiation therapy is common across all anatomic locations?
Fatigue
What is the most common s/e of radiation therapy above the abdomen? Most common s/e of the abdomen and below?
Above = hair loss
Abdomen and below = diarrhea
What areas of the body when exposed to radiation therapy can cause N/V?
Brain, pelvis and abdomen
What anatomic areas when exposed to radiation therapy can cause urinary changes?
Abdomen, rectum and pelvis
What is the allowable radiation dose for the whole body?
5,000 mrem
What is the allowable radiation dose for the extremities?
50,000 mrem
What is the allowable radiation dose for lens of the eye?
15,000 mrem
What is the allowable radiation dose for pregnancy?
500 mrem
How many mrem’s are released from a CXR?
5-10 mrem
How many mrem’s are released during a coronary angiogram?
1,500 mrem
How many mrem’s are released during an angioplasty?
5,700 mrem
How many mrem’s are released from a CT?
5,000 mrem
What 3 factors can affect radiation scatter?
Collimation - the “size” of the window that radiation is allowed to escape
Object thickness - the thicker the object, the more the radiation will scatter (this is partially why imaging on obese patients can be of poor quality)
Air gap - fairly straightforward; the longer the distance to travel, the more opportunity there is for scatter to occur
At what dose of mrem does transient erythema occur?
200,000 mrem
What dose of mrem is unlikely to cause fetal s/e after 20 weeks of gestation?
Less than 10,000 mrem
With a direct source of radiation, what is the relationship of distance to exposure rate?
For every doubling of distance (or factor increase by 2) you will decrease exposure rate by 1/4
(if you go from 2 to 8 feet, and starting mrem is say 100 mrem/min, you have doubled your starting distance 3 times, 2 -> 4 -> 6 -> 8, be VERY careful when doing this math and be comfortable with the difference between factor increases, which is what this is, and standard multiplication. So, you have 3 factor increases of distance, so you will multiply 100 by 0.25 3 times) -> 100 x 0.25 = 25 mrem/minute (first factor), 25 x 0.25 = 6.25 mrem/minute (2nd factor), 6.25 x 0.25 = 1.5626 mrem/minute (3rd factor). This illustrates why distance is so valuable in reducing radiation exposure
You are 3 feet away from a radiation source and receiving 750 mrem/min of radiation, you move away from the radiation source to 15 feet. What is your new exposure rate?
2.93 mrem/minute (remember, this is factor multiplication, for each doubling of the distance you reduce radiation exposure by 1/4 and in this scenario you have doubled the distance 4 times)
What occurs is you leave a dosimeter on your car dashboard?
Because it is being exposed to cosmic (beta) radiation it can falsely elevate/trip the dosimeter
The interactions between what create the images of an MRI?
The interactions between the static magnetic field and the individual atom nuclei
Why is MRI, in general, a safer option than a CT?
Because an MRI does not use ionizing radiation there are less cell death/damage risks
Describe how an MRI orients molecules/atoms to create images
The magnetic field orients the nuclei of hydrogen molecules to north/south poles and radio wave pulses change the orientation of specific atoms which radiates energy
What property allows MRI to create detailed pictures?
Each atom/molecule “resonates” at a unique frequency, and when exposed to the properties used in an MRI machine, each atom creates an image unique to that atom. So hydrogen will look different than iron
What is a T1 MRI image most useful in identifying?
Due to the good grey-white matter contrast, it is good to examine anatomy.
fat appears bright, water appears dark in T1
What is a T2 MRI image most useful in identifying?
Because of it’s ability to identify tissue edema, it is very useful in identifying tissue pathologies
How does fat and water appear on T1 vs T2 MRI images?
T1 = Fat is bright, water is dark
T2 = Fat is darker than water
What is the most common contrast medium used in MRI?
Gadolinium
How does gadolinium work?
It Alters the magnetic properties of nearby water molecules which enhances the quality of MRI images.
What pieces of equipment, in general, should not be introduced in a room with MRI?
Oxygen/nitrous oxide tanks
Anesthesia machine
Monitors
Infusion pumps
Stretchers
Crash carts
Most of these items are generally located just outside
What is the primary danger/risk of MRI?
Projectile risk. Another concern is heating, particularly of metal components that have been implanted in someone
Dr. Mordecai gave an example of how she had the LINX procedure for acid reflux, and because of that she isn’t safe in an MRI room
Do the AANA standards of care have any changes/accommodations for a patient in MRI?
No, these standards apply regardless of the patient care setting
What type of MRI scans (think region of the body being scanned) have a high incidence rate of brachial plexus injury?
Abdominal scans - because you have to place the arms over the head to get them out of the way of the scan
What s/sx can occur if you approach the MRI field rapidly?
dizziness, HA, light flashes, nausea
What implantable devices should warrant caution before being exposed to an MRI? Which are generally safe?
Caution/may not be safe = Pacemakers, AICDs and insulin pumps
Generally safe = Heart valves, endovascular and biliary stents after the 8 week mark, coronary stents, vascular ports, IVC filters and most orthopedic implants
What type of stent is immediately safe for MRI (no waiting period necessary to allow for healing/attachment to native vessel)?
Coronary stents
What differences are present between normal light vs a laser?
A laser has a specific wavelength, a focused narrow beam and high intensity
Normal light = many/varying wavelengths and spreads out in many directions
What type of radiation does a laser make use of?
Electromagnetic
What are the 3 properties listed on the powerpoint that describe the behavior of lasers?
Monochromatic - all photons of a laser are of the same wavelength
Coherence - the travel of the photons is synchronous; they do NOT move randomly
Collimation - the laser beam photons are nearly perfectly parallel which allows for a very focused beam
What are the 3 primary lasers used in medicene?
Argon, CO2 and Nd:YAG lasers
What laser has minimal scatter/minimal damage to surrounding tissue making it preferable for vocal cord/oropharynx surgery?
CO2 laser
What laser has modest penetration (0.05 - 2mm) and is commonly used for dermatology?
Argon lasers
Why does a CO2 laser cause minimal to no to surrounding tissue?
The CO2 laser is well absorbed by water, meaning it disperses very little heat
What is the most powerful laser with deeper penetration of 2 - 6mm and useful in tumor debulking?
Nd:YAG lasers
What are the 2 primary risks we are concerned with when lasers are in use?
Atmospheric contamination (think condyloma surgery) and airway fire
What are the 5 hazards listed in lecture of laser use?
Atmospheric contamination, perforation of a vessel/structure, embolism (think air embolism from a hole in a vessel), inappropriate energy transfer and airway fire
Why are we so concerned about atmospheric contamination from laser procedures?
The plume of smoke can transmit particulates that can be carcinogenic in nature
What are the basic/generic safety considerations with laser use?
Laser glasses for provider
Laser glasses for patient with eyes taped
Windows covered
Laser plume masks for vaporized viruses and particulates
Appropriate suction
Water/saline irrigation on back table
Don’t tent drapes/have pockets of oxygen
What is the fire triad?
An ignition source, fuel (oxygen) and an oxidizer
What are the 2 major sources of OR fires?
ESU (electrical surgical units, think cautery devices) and lasers
What are some interventions you can use to help maintain airway fire safety?
Laser-resistant ETTs
Low-inspired (21% if possible) O2
Wet pledgets around the ETT
Methylene blue in the ETT cuff
Use scissors to cut into trachea instead of bouvie
Remove ETT during laser procedure and reinsert ETT prn sats
Why must TIVA be a backup if there are planned apneic periods during surgery due to airway fire concerns?
If you are apneic, you aren’t breathing in any volatile; you want to prevent surgical awareness, so you can use TIVA to help maintain anesthesia
What should be included in the anesthesia care plan if airway fire is of concern?
Methylene blue ETT cuff, saline gauze protection of face/airway, try to convince the surgeon that short repeated pulses of a laser is better instead of long/continuous, avoid O2 concentration of greater than 30%, avoid nitrous and communicate
What type of radiation does not travel through the air?
Mechanical
What generates contrast in an MRI?
The time until tissue relaxation when the radiofrequency is turned off (this is determined by the various densities of hydrogen nuclei in tissues and different chemical/physical properties)
What MRI image occurs when the magnetic vector relaxes?
T1
What MRI image occurs when the axial spin relaxes?
T2
What does the bat wing pattern on a CXR indicate?
Fulminant pulmonary edema from CHF
What condition occurs due to transposition of a loop of large intestine in between the diaphragm and the liver without pain?
Chilaiditi sign
Chilaiditi sign is the anatomic variant without s/sx like pain, SOB or torsion. Once the extra s/sx occur, it becomes Chilaiditi syndrome
The anatomical variant of Chilaiditi sign/syndrome mimics what medical emergency on CXR?
Bowel perforation
What 3 factors contribute to the depth of a thermal injury?
Contact temperature
Duration of contact
Thickness of skin
What layers of the skin are generally involved in heat burns?
The epidermis and dermis
What is the primary concern at the cellular level with an electrical burn?
Disruption of membrane potential
A friction burn is a combination of what 2 types of burns?
Mechanical and heat
The magnitude of an electrical burn depends on what 3 factors?
Pathway of current
Resistance to current flow
Strength and duration of current flow
What caustic reactions can be caused by a chemical burn?
pH alteration
Disruption of cell membranes
Direct toxic effect on metabolic process
The magnitude of a chemical burn is related to what 2 factors?
The duration of exposure
Nature of the agent
Acidic agents cause necrosis by using what?
Necrosis by coagulation
Alkali agents cause necrosis by using what?
Necrosis by liquefaction
What burn type is most likely to have weird/irregular injury patterns?
Chemical burn (think splash pattern from a liquid or aerosolized spread from a powder)
The magnitude of a radiation burn relies on what 2 factors?
Dose and time of exposure
Types of particles
________causes damage from radiation burns
Ionization
What are the examples from lecture of radiation burns?
Sunburns
Therapeutic radiation
Diagnostic procedures
Nuclear industry workers
What type of burn is not included in TBSA?
1st degree burns
What populations tend to have deeper burns related to thin skin?
Adults over 55 and kids under 5
Due to burns ability to evolve/change in the early period, when does true staging of a burn occur?
24 - 72 hours after the initial burn
What is the primary difference between superficial and deep partial thickness burns?
Deep extend more deeply into the dermis with less pain, have a longer healing period of 21 - 28 days and require skin grafting
What type of burn has a surface that is dry and inelastic?
3rd degree burns
1st degree burns are dry with/without small blisters
List the rule of 9’s for each body region for an adult
Head = 9%
Each arm = 9%
Each leg = 18%
Trunk = 36% total
Perineum = 1%
for each above except perineum, they account for TOTAL area of each region, anterior and posterior account for half of that total. So anterior trunk would be 18%, posterior left arm would be 4.5%
The palmar method of estimating burns account for how much TBSA measured?
The palm of the patient is approximately 1% BSA
How does being obese change burn estimation?
Underestimate torso burns
Overestimate extremity burns
Android (fat accumulates in the upper part of body mainly abdomen/chest) vs gynecoid (pear shape) shape important
At what TBSA do patients develop severe enough burn shock to warrant IV resuscitation and admission to the ICU?
Greater than 20% TBSA
Why are we starting to become more cautious about fluid resuscitation in burn patients?
Over resuscitation can cause abdominal compartment syndrome, pulmonary edema/ARDS
What are the general metabolic responses to trauma/burns?
Auto-cannibalism - leading to loss of fat, loss of lean body mass (proteolysis), gluconeogenesis, lipolysis, hyper-metabolism and insulin resistance
What metabolic effects occur with a greater than 40% BSA burn?
Metabolic rate doubles
Cannibalism for months
Immunodepression, recurrent infections, poor wound healing
Increases in cortisol, catecholamines, and glucagon lead to what changes in carbohydrate metabolism in a burn patient?
Accelerated hepatic gluconeogenesis
Peripheral insulin resistance (50-70%) -> (causes post-receptor defect hindering uptake related to the extent of the burn which can last up to 3 years)
Impaired intracellular glucose transport
Accelerated lipolysis is caused by what in a burn patient?
Excessive B2/3 adrenergic stimulation (this in turn is stimulated by elevated glucagon, TNF and IL)
treat with beta blockade to reduce lipid oxidation and therefore decrease metabolic rate
The loss of muscle mass in a burn patient is proportional to what?
The degree of stress, or rather the severity of the burn. In severe burns the loss of skeletal muscle can be doubled
What are the secondary priorities after burn stabilization?
Pain control
Thromboprophylaxis
Wound closure
Nutritional support
Control of hyper-metabolism
Prevention of infection
What administration route is generally contraindicated in burn patients?
IM route
What 3 factors from a burn lead to copious loss of fluid?
Impaired endothelial barrier
Increased capillary permeability
Loss of intravascular oncotic pressure
Aggressive fluid resuscitation is generally indicated for what BSA?
Greater than 15% BSA
What should be considered on day 2 after fluid resuscitation?
Colloid administration
How does the parkland formula calculate fluid needs?
4 ml/kg/%BSA (2 ml/kg/BSA in the first 8 hours, the other 2 ml/kg/BSA in the next 16 hours)
What is the army rule of 10 for adult burns?
10 ml/hr x TBSA, if over 80 kg add 100 ml per 10 kg to the hourly rate (so if you are 100 kg, you would add 200 ml/hr to the calculated rate)
Based on the parkland formula, how much fluid resuscitation is needed for a 60% TBSA for a 80 kg patient?
4 x 80 x 60 = 19,200 mL
Base on the army formula, how much fluid resuscitation per hour is needed for a 115 kg patient with a 35% TBSA?
10 x 35 + (35 x 10) = 700 ml/hr
*Some math was simplified here, you add 100 ml per 10 kg, which can be simplified to 10 ml per kg over 80 kg. In this case, it’s 35 kg over 80, so 35 x 10 = 350 ml)
What findings upon an assessment of a burn warrant transfer to a certified burn center?
Full thickness > 10% BSA
High voltage electrical burns
Chemical burns
Associated inhalation injury
Face, hands, feet, perineum, major joint burn(s)
What is the goal UOP with burn fluid resuscitation?
1 cc/kg of UOP (the slide does NOT specify a timeframe, I’m assuming it’s hourly)
Why is LR the crystalloid of choice rather than NS?
Large volume administration of NS can cause hyper-natremic hyperchloremic acidosis
What is the max fluid rate/hour in burn resuscitation? Max total volume in 24 hours?
Hourly = 1500 ml/hr
Total in 24 = 250 ml/kg
If children are under 20 kg, what maintenance fluid is added?
D5LR
If under 14 years old and under 40 kg, what fluid resuscitation formula do you use?
2 - 4 ml (of LR) per kg x kg x %TBSA
goal UOP of 0.5 - 1 ml/kg/hr
What is the albumin infusion rate for a 30 - 49% TBSA for less than 70 kg? 70 - 90? Over 90?
<70 = 30 ml/hr
70 - 90 = 40 ml/hr
>90 = 50 ml/hr
What is the albumin infusion rate for a 50 - 69% TBSA for less than 70 kg? 70 - 90? Over 90?
<70 = 70 ml/hr
70 - 90 = 80 ml/hr
>90 = 90 ml/hr
What is the albumin infusion rate for a 70% or greater TBSA for less than 70 kg? 70 - 90? Over 90?
<70 = 110 ml/hr
70 - 90 = 140 ml/hr
>90 = 160 ml/hr
What is the pediatric colloid infusion rate?
4 - 7 ml/kg at the rate of 0.5 ml/minute
What are the 2 cardiac “phases” during a burn?
The resuscitative phase or the ebb state (simple version is, CO is low, SVR is high)
The post-initial burn or flow state (CO is high, heart is hyperdynamic and SVR is decreased -> give beta blockers)
With a circumferential burn, what procedure can help alleviate the restrictive lung defect?
Escharotomy
What pulmonary effects begin immediately after a burn?
Pulmonary hypertension
Pulmonary capillary alveolar membrane disruption
Decreased plasma oncotic pressure
Increased extravascular lung water…impaired gas exchange
Bronchospasm is common -> bronchodilator therapy
What carboxyhemoglobin level would you expect after an inhalation injury?
Greater than 10%
What topical antibiotic is contraindicated in facial burns?
Silvadene cream
What antibiotic would you use for the eye lids? The eyes?
Lids = bacitracin
Eyes = erythromycin
What type of poisoning would you be concerned about from an inhalation injury from a car fire? Tx?
Cyanide poisoning, treat with vitamin B-12 (cyanocobalamin)
What route of entereal nutrition administration is ideal for burn patients?
J-tube (jejunum) -> allows for continuous tube feed with minimal aspiration risk. Advantageous, especially with the high liklihood of multiple OR trips
What factors greatly alter the pharmacokinetics/dynamics of drugs after a burn?
Plasma protein concentration is changed d/t loss of albumin and increases in free fractions/VD, alterations in ACh receptors (they are upregulated after a burn) and changes in CO (ebb/flow)
Why must Sux be used with extreme caution in burn patients?
D/t upregulation of nACh receptors, they are very sensitive to Sux
What paralytic are burn (greater than 25% BSA) patients resistant to?
Non-depolarizers
T/F: The severity of a burn correlates to the patients sensitivity to a depolarizer?
False
Do AANA standards of care make changes/accommodations for burn patients?
No; however it may be harder to keep devices attached. You may need to suture devices or place electrodes in weird places
What airway assessment findings indicate an inhalational injury?
Hoarseness, wheezing, SOB
Carbonaceous sputum
Singed nasal & facial hairs
Deep facial burns
Comatose patient
>40% TBSA
When is propofol a good choice for burn induction?
During the flow phase (the heart is hyperdynamic here)
When is ketamine a good choice for a burn patient induction?
During the ebb phase (the CO is low, and ketamine will help preserve the CO)
Why must etomidate be used with care in burn patients?
D/t adrenal insufficiency concerns
What is the ratio for blood volume lost per burn excised/autograft harvested?
2.6% blood volume lost per 1% burn excised/autograft harvest
What are some interventions to help reduce blood loss related to burn injury?
Use of topical thrombin, staged procedures, subq vasoconstrictors
What are the choice vasopressors in burn related shock?
Vaso and Levo
If CVP is less than goal, how much do you increase IVF rate?
By 20 - 25%
What drugs make up tumescent LA?
1g of lidocaine + epi + 10 mEq of bicarb per 1000 cc of NaCl
What is the max dose of tumescent LA?
55 mg/kg
the burn slide says the max is mg/kg, prior anesthesia pharm lecture says its 55 ml/kg, not sure which one to stick with
What are the pros/cons of tumescent LA?
Pros: Decreased blood loss, easy excision of granulation tissue, shorter surgery and no hematoma/bruising
Cons: The large amounts of lidocaine and epi can have unpredictable effects on the heart
What must be done if nebulized heparin is indicated in an inhalation burn injury?
You must coadminister it with albuterol, otherwise bronchospasm may occur
What are your goal pCO2 and pH for a burn patient (assuming they are mechanically ventilated)?
PCO2 of 30 - 35, pH greater than 7.2
A bladder pressure of what indicates early intra-abdominal hypertension? What pressure indicates compartment syndrome?
IAH = greater than 12 mmHg
Compartment = greater than 20 mmHg (do a stat ex-lap)
What are the basic anesthesia post-op management goals in a burn patient?
DVT prophylaxis, Beta blocker admin, Nutritional support, Temp control
What surgical procedure may be used to alleviate extremity pressure to allow for return of a pulse?
Escharotomy
Does scrotal swelling require treatment in a burn patient?
No, even extreme swelling does not warrant treatment
T/F: abx and steroids are indicated in burn resuscitation?
False
they may be needed later AFTER resuscitation d/t the patients now immunocompromised state
What are the burn dressings listed in lecture?
Topical antibiotics Silvadene and Sulfamylon
Silver dressings
Silverton water or saline every 8 hours
Silver nitrate
Temporary skin substitutes such as Biobrane
No Silvadene to the face
What condition could allow for easy visualization of the fissures of the lungs on CXR?
Fluid within the pleural space or if the visceral pleura is thickened
Fluid losses in a burn patient are a function of what 2 factors?
Burn size and patient weight
What burns generally require higher volumes of fluid resuscitation?
Inhaled burns, electrical burns, or delayed resuscitation
At what carboxyHgb level do overt s/sx (HA, N/V) begin to occur?
15 - 20%
At what carboxyHgb level do s/sx of severe toxicity (seizure, ARF or myocardial ischemia) occur?
20 - 25%
At what carboxyHgb level do unconsciousness/death occur?
Greater than 25%
Of the bipolar limb leads, which is +/+, +/- and -/-?
+/+ = LL
+/- = LA
-/- = RA
What part of the heart do the traditional limb leads monitor?
The inferior aspect of the heart
What parts of the heart do the precordial leads monitor?
The anterolateral aspects of the heart
What does V1/2 monitor?
The septal wall
What does V3/4 monitor?
The anterior wall
What does V5/6 monitor?
The lateral wall
In RVH, what EKG changes would you expect to see?
Greater depolarization toward V1 and the QRS in V1 gets very positive with small R waves
In LVH, what EKG changes would you expect to see?
Large S waves in V1, larger R wave in V5
What EKG change is indicative of myocardial ischemia?
Inverted symmetrical T-waves
What EKG change is indicative of myocardial injury?
ST changes
What EKG change is indicative of myocardial infarction?
Q waves - this indicates necrosis of an old infarct (this is the bump after the QRS)
What type of pacer lead is more sensitive to EMI (electromagnetic interference)?
Unipolar
What type of pacer lead has multiple electrodes within 1 lead but accesses multiple chambers of the heart?
Multipolar
List what each roman numeral in a pacer is meant to identify
I = chambers paced
II = chambers sensed
III = response to sensing
IV = rate modulation
V = multi-site pacing
What does inhibition of III on a pacer do?
This means if the pacer sense a spontaneous depolarization, the pacer won’t activate/pace
What type of pacing is most common to see if the patient has dilated cardiomyopathy?
Bi-ventricular pacing (you have leads in the RA, and both ventricles) for cardiac resynchronization or CRT
What are the basic criteria for a patient to be placed on Bi-V pacing?
Moderate/severe CHF (EF less than 35% ish), intraventricular conduction delays (BBB) or a history of cardiac arrest
What modes are asynchronous pacing with no rate modulation?
DOO and VOO
If you place a magnet on a pacer, what mode should the pacer default to?
Asynchronous mode with no rate modulation (DOO or VOO)
What kind of cautery device must be used with care in the presence of an AICD/BiV?
Monopolar cautery (in bipolar, the current is localized to the 2 electrodes making it safer for pacers)
What is the primary thing an AICD measures? Secondary measurement?
Primary = R-R interval
Secondary = QRS
Where is a CVP line supposed to terminate?
At the junction of the RA and IVC
What 2 factors is CVP highly dependent on?
Blood volume and vascular tone
Normal CVP range?
1 - 7 mmHg
How does PPV affect CVP?
It artificially increases it
How does a pericardial effusion affect CVP?
It increases it
List the CVP waveforms and what they measure
A wave = atrial kick, occurs after the P-wave
C wave = isovolumetric contraction of the ventricle causing the tricuspid to bulge backwards, occurs after the R wave
X descent = decrease in atrial pressure during systole
V wave = venous filling of the atrium, occurs during late systole after the T-wave
Y descent = tricuspid valve opens and blood goes into the ventricle, occurs after the v-wave and also after the T-wave
How does A. Fib change the CVP waveform?
No A-wave and a larger C-wave (loss of atrial kick means more blood stays behind in the atria)
How does tricuspid regurgitation change the CVP waveform?
No x-descent because the valve is incompetent (blood flows backwards through the valve)
How does tricuspid stenosis change the CVP waveform?
You have a tall A wave with a y-descent of longer duration and lower amplitude
What does each lumen of the PA catheter do?
Distal end monitors PAP, the 30 cm proximal port monitors CVP, the 3rd lumen leads to a balloon at the tip and the 4th lumen houses the temperature thermistor
Describe at what point on the PA catheter you would find the: RA, RV, Pa and where you would wedge the catheter
RA = 20 - 25 cm
RV = 30 - 35 cm
Pa = 40 - 45 cm
Wedge = 45 - 55 cm
What are 2 s/sx from lecture that can indicate Pa rupture?
Hemoptysis and hypotension (potentially profound hypotension)
What are some treatment options of Pa rupture?
Ensure adequate oxygenation (endobronchial intubation, single or double lumen tube), PEEP to tamponade bleeding, reverse anticoagulation (unless on bypass), bronchoscopy to control bleeding, float balloon into the rupture, but surgery at some point must be done
PAWP is a measurement of what?
Indirect measurement of LAP
Where should the PAC tip be?
Zone 3
LVEDP is a poor estimate of what?
Compliance
Aortic regurgitation
PEEP
VSD
Mitral stenosis/regurg
Mitral regurg creates what changes on the PAC waveform?
Tall V-wave, C wave fuses with the V wave, no x descent
PAC waveform changes have no sensitivity to LA compliance or volume
Mitral stenosis creates what changes on the PAC waveform?
Slurred early Y-descent and the A-wave may be absent (especially if they are in A. Fib)
What PAC changes occur with an acute LV MI?
Tall A-waves, LVEDV and LVEDP increase, PAWP increases
Assuming Hgb, arterial saturation and oxygen consumption are static, what is the relationship of a mixed Vbg and CO?
An indirect indicator of CO; if mVbg decreases then CO is likely decreasing
What is the CO equation?
CO = SV x HR
What is a normal CO?
5 L/min
What is a normal SV?
75 ml
What is a normal SVR?
1200 dynes/sec/cm^5
What is a normal PVR?
80 dynes/sec/cm^5
What is a normal mixed venous saturation?
75%
Describe how bolus thermodilution works
You inject a cold liquid, and based on the temperature change you measure CO. If CO is high, the fluid doesn’t have time to increase in temperature (or rather, the temperature of the fluid doesn’t change much), if CO is low, the fluid has more time to increase in temperature and CO is low
What conditions can make thermodilution inaccurate?
Intra-cardiac shunts
Tricuspid/pulmonic regurgitation
Mishandling of the injectate
Fluctuations in temperature
Rapid fluid infusion
When is CCO (continuous cardiac output) more accurate?
When the patient is under positive pressure ventilation
Why is pulse contour not as accurate as CCO?
It relies on an algorithm to determine CO and ventricular compliance
What are the downsides to using pulse contour to estimate CO?
Several conditions can make it inaccurate as it relies on an arterial waveform; atrial fibrillation, site of arterial puncture can change it, quality of arterial trace (this is affected by vasopressors) and requires frequent re-calibration
What mode of an echo uses narrow beams to measure tissue planes?
M-mode
good to examine something like a ventricular wall mass
What echo mode shows real time motion and shows function?
2-D
What echo mode determines speed/direction?
Doppler - it also makes use of color
What are the primary windows used for an echo?
Parasternal: 3-5 ICS
Apical: @PMI
Subcostal: just below xiphoid
What is the great overall echo view?
Parasternal Long Axis
What echo view is good for LV function/volume assessment?
Parasternal short axis
What echo view is good to compare the ventricles, tricuspid/mitral valve function and examine the descending aorta?
Apical four chamber
What echo view allows for examination of all 4 chambers and is the best choice to diagnose a pericardial effusion?
Subscostal four chamber view
What echo view is best to determine fluid status?
Subcostal IVC - allows you to directly examine the IVC
Contraindications to a TEE?
Esophageal varices or laparoscopic banding
What types of burns generally require skin grafting and/or other invasive surgery to fix?
Deep partial thickness (2nd degree) and 3rd degree burns
What is the relationship of cortisol, TNF, IL-1 and IL-6 to protein metabolism?
Cortisol improves it, the rest worsen it
What is the pediatric fluid resuscitation rate using the US army ISR rule of 10?
3 x TBSA x kg
When do you start colloids in a burn patient?
If at the 8 - 12 hour mark the hourly fluid rate exceeds 1500 ml/hr or the projected 24 hour total approaches 250 ml/kg start 5% albumin infusion
Where would a pericardial effusion most likely be found on an echo?
Next to the right heart using a subcostal 4 chamber view
