Critical Care Flashcards
Intubation and Mechanical Ventilation:
Who needs it
- Respiratory failure: lose the ability to ventilate adequately
- Hypoxemia
- Hypercarbia
- Inability to protect airway
- Failed non-invasive ventilation (BiPAP or CPAP)
- Procedures requiring general anesthesia
Rules for Intubation
- Always intubate under direct visualization of the vocal cords
- Always confirm ET tube placement with auscultation of all lung fields
- Follow up with a chest x-ray
- Proper position of ET tube is 3- 5cm above the carina
complications of ventilhation
- Reduced MAP after intubation and implementing mechanical ventilator support is common due to:
- Reduced venous return from positive pressure ventilation
- Reduced endogenous catecholamine secretion
- Administration of drugs used to facilitate intubation
- Usually volume responsive hypotension
What is the preferred method of ventilation for long term vent management
Tracheostomy
indications for tracheostomy
- Long-term or permanent airway obstruction
- Long-term mechanical ventilator
- Unable to clear their airway secretions
- Facilitate liberation from mechanical ventilator
benefits of tracheostomy
- Improved oral hygiene
- More comfortable
- Need for less sedation
- Can progress to speaking valves and normal eating practices possibly
- Decreases airway resistance and dead space -> lead to faster ventilator wean
- Easy access to airway
complications of tracheostomy
- Acute
- Hemorrhage
- Mal-positioning
- Pneumothorax/pneumomediastinum
- Neck hematoma
- Long Term
- Tracheoesophageal fistula
- Tracheo-innominate fistula
- Tracheomalacia
- Tracheal stenosis
name 4 types of ventilhator modes
- Ventilator modes:
- Volume control
- Pressure control
- Pressure support
- Non-invasive ventilation: BiPAP
Complications of mechanical ventilhation
- Barotrauma – pneumothorax, SQ emphysema, pneumomediastinum, pneumoperitoneium, alveolar rupture
- Lung injury
- Ventilation/perfusion mismatch
- Decreased hemodynamics
- Myopathy
- Ventilator assistant pneumonia
•Patients who can be Extubated
- Is the patient stable on minimal ventilator settings?
- FiO2 <50% with PaO2 by blood gas>60
- PEEP<10
- PS<7
- Did the patient pass a spontaneous breathing trial (SBT)?
- PSV with PS typically of 7 and PEEP of 5 (some institutions will do PS of 0)
- Rapid-shallow breathing index (RSBI) <100
- Ration of RR to TV
- No evidence of increased work of breathing or hemodynamic instability
•Fraction of inspiration oxygen (FiO2)
- Definition: fraction of oxygen in the volume being measured
- Room air: 21%
- 1-2L via nasal cannula: 25%
- 10L via nonrebreather: 50%
•Should be on the lowest possible FiO2 necessary to meet oxygenation goals, usually peripheral saturations between 90-96%
•Increased FiO2 can lead to oxygen toxicity, parenchymal injury, hypercapnia, and absorption atelectasis
•Positive end expiratory pressure (PEEP)
- Definition: pressure added at the end of expiration that prevents alveolar collapse
- Usual initial dose if 5 cm H20 but can increase up to 20 cm H20
- Recruits alveoli that have collapsed, which increases the surface area for gas exchange
- ARDS patients are typically treated with low TV and high PEEP
- Increased PEEP can lead to decreased cardiac function, barotrauma, and impaired cerebral venous outflow
•Tidal Volume (TV)
- Definition: the amount of air delivered with each breath
- Ideal TV is 6-8 mL/kg of IBW à use IDEAL weight
- Patients with ARDS should have low TV of <6 mL/kg of IBW
•Pressure Support (PS)
- Definition: a set pressure that is delivered during inspiration (driving pressure)
- Can be set anywhere from 0-30 mmH20, normal is usually 7-10 mmH20
- The higher the PS, the larger the patient’s TV will be
Volume Control
- These are good “set it and forget it” modes
- Less useful for awake patients
- Can be very uncomfortable for patients
Synchronized intermittent mandatory ventilation
- A good starter weaning mode that allows patients to take independent breaths between set breaths.
- Patient triggered breaths will not receive the set TV, but will receive the set PS
- Better preservation of respiratory muscle function
- If patient is tachypneic there is a high likelihood of vent dyssynchrony
Assist Control
- A good mode for patients that are sedated or newly intubated
- Clinicians set the minimal minute ventilation by setting the RR and TV
- Patient triggered breaths will receive the set TV
- If patient is tachypneic there is a high likelihood of Auto-PEEP (incomplete expiration prior to the initiation of the next breath leads to air trapping)
Pressure Control
Each breath is given a set amount of pressure via the ventilation
- The clinician is setting the inspiratory pressure and inspiratory time
- The resulting TV depends on the set driving pressure, TV will be varied
- Advantages: Can have strict control over the airway pressure which can help with barotrauma and fresh suture lines
Disadvantages
- Can not wean from this mode
- Can be very uncomfortable
Pressure Support
Only set the pressure support and PEEP
- The patient’s TV and RR are not set, rather the patient receives assistance with each breath
- Patient needs to initiate the breath
- The preset variable is the set amount of PS and PEEP
- Ideal for weaning
- More comfortable mode
Patient’s need close monitoring due to no set TV and minute ventilation and can lead to hypoventilation
Non-invasive ventilation: BiPAP
Used for non-intubated patients
- Used for patients with impending respiratory failure or who is struggling after extubation
- BiPAP provides assistance with the mechanics of ventilating (regulating oxygen and carbon dioxide)
- Can adjust the inspiratory and expiratory pressures to achieve a desired TV
Advantages:
- Can prevent intubation
- Intermittent use
Disadvantages:
- Claustrophobic, patients tend not to tolerate it
- Patient’s can not eat or drink while mask is on
- Can dry up secretions and cause a mucus plug
define Acute Respiratory Distress Syndrome (ARDS)
- Acute, diffuse, inflammation form of lung injury that is associated with a variety of etiologies
- High mortality rate: ~30%
criteria for dx of ARDS
- Bilateral infiltrates on chest x-ray
- Progressive respiratory failure
- Hypoxemia that does not respond to increase FiO2
most likely causes of ARDS
- Sepsis
- Pneumonia
- Trauma
- Multiple transfusions
- Aspiration of gastric contents
3 phases of ARDS
- Exudative
- Alveolar edema occurs in dependent regions from injury to the alveolar barrier
- High concentrations of inflammatory cytokines -> recruitment of leukocytes
- Usually occurs within 7 days of chest x-ray findings
- Proliferative
- Usually the next 7-21 days, associated with recovery
- can wean to extubation during this time, but still may have symptoms
- Fibrotic changes can happen late in this phase -> poor recovery predictor
- Fibrotic
- Not all patients move to this phase
- Develop interstitial fibrosis with emphysematous changes
- Increased risk of mortality
tx ARDS
- ARDS is a syndrome not a disease process -> TREAT UNDERLYING DISEASE
- Ventilator support!!!!
- Use the lowest possible settings for PEEP, TV, and FiO2 to achieve a PaO2 via arterial blood gas of 55 mmHg
- Protect lungs from barotrauma with low tidal volumes - Target <6 mL/kg of IBW
- Goal pH via arterial blood gas >7.3
- Avoid aggressive fluid resuscitation if possible, can cause worsening pulmonary edema
- Goal CVP < 4 and PCWP <8
- Balance between diuresis and end organ perfusion
- Prophylaxis against VTE and gastritis
- Avoid unnecessary procedures
- Aggressive treatment for suspected infections
why are low tida volums important in ARDS pts
- A large multicenter trial of ARDS patient found that TV of 6mL/kg with plateau pressures <30 cm H2O had significant improvement in mortality over TV of 12 mL/kg
- Over-ventilation caused more alveolar damage which worsened inflammation
- target a goal TV of 6-8 mL/kg
- always look out of elevated plateau pressures
indications for arterial lines
- Unstable patients who require vasopressor support
- Severely hypertensive patients requiring IV antihypertensive
- Strick blood pressure control for neuro patients
complicatios of arterial lines
- Arterial occlusion can cause limb ischemia
- Limit mobility
- Line infection -> rare for arterial lines to cause infection but is a possibility
possible sites of arterial lines
Brachial
Radial
Femoral
Axillary
what is the most central arterial lines / most accurate
femoral
Risk of vascular injury or retroperitoneal bleed à Higher risk of infection
which arterial line is most difficult to place but carries less risk of complete occlusion
Axillary
Durable, long lasting and rarely positional
Increased risk of vascular injury
Harder to compress, higher likelihood of hematoma
compare and contrast brachial bvs radial arterial lines
Brachial
Most comfortable for the patient usually
Larger artery then radial leads to less positional issues
If thrombus forms, risk of compromising whole arm
Radial
Least invasive
Smallest artery used, tends to be most positional/unreliable
Usually annoying to the patient
indications for Central Venous Lines
- More “long term” access (7-14 days verse 3 days for peripheral IV)
- Administration of certain medication
- Dialysis access
- Close monitoring of central pressures
- Frequent and recurrent lab draws
CVP Measurement & normal range
- Can obtain a central venous pressure (CVP) off a central line placed in the IJ or SC vein.
- Normal range is 0-8 mmHg
- This measurement is used in conjunction with other factors to determine fluid status
- Measurement should be made while patient is supine
- Normal respiratory variation is seen
complications of central venous lines
- Venous air embolism – keep patient in Trendelenburg position during placement
- Pneumothorax
- Catheter tip malposition – always check x-ray prior to use for IJ and SC lines
- Thrombotic occlusion
- Venous thrombosis – femoral line with highest risk
- Infection – line should ideally be changed every 7-14 days
what line are we highly cooncerned for infection and how do we monitor this ?
what are the common pathogens that cause infection?
- Most common pathogen is coag-negative staphylococci, Staph Aureus, gramnegative Bacilli
- should have a high suspicion for any patient with a central line that has been in for over 48 hours who has a new leukocytosis and fever
- Obtain blood cultures
- Remove line and replace in a new location if possible
- Start empiric antibiotics
central venous lines can be placed in..?
Internal Jugular
Femoral
Subclavian
- The “ideal vein” -> Least risk of infection
- Most difficult to place
Subclavian
- Increased risk of pneumothorax & hematoma
- Most comfortable
- Unable to use ultrasound
•Best venous site for emergency access
Femoral
- Easily accessible -> US guided below inguinal ligament – otherwise high risk for RP bleed
- Risk for vascular injury -> Increased risk of bleeding
- Limited mobility
- Increase risk of infection
best venous site for for Swans and pacing wires
Internal Jugular
- Easily accessible using ultrasound
- Provides a “straight shot” to the right atrium
- Uncomfortable for patients
what is a Swan-Ganz Catheters
•A specialized catheter that gives continuous measurements of right heart filling pressures and indirect left heart filling pressures
Swan-Ganz Catheters measure
•Central venous pressure (CVP) - which is equal to the RA pressure (Normal < 8 mmHg)
•Right ventricular pressure (RV) -Normal (systolic/diastolic) 15-30/0-8 mmHg
•Pulmonary artery pressure (PAP) - Normal (systolic/diastolic) 15-30/4-12 mmHg
•Pulmonary capillary wedge pressure (PCWP)- •this is obtained when the balloon is inflated and gives you an estimated of the left side heart pressure (most inaccurate measurement of swan-Ganz catheters) •Normal <12 mmHg
•Can measure cardiac output and mixed venous oxygen saturation
•Cardiac output (CO) - done with thermo-dilution, normal 3-7 L/minute
•Cardiac index (CI)- •relates cardiac output from the LV to body surface area, normal >2.2 L/min
•Mixed venous oxygen saturation (SVO2) - the percentage of oxygen bound to hemoglobin in blood returned to the PA (Normal >60%)
complications of Swan-Ganz Catheters
- Mal-positioning
- Myocardial or pulmonary injury – always advance Swan-Ganz catheter with the balloon inflated
- Cardiac valve injury – always pull back the Swan-Ganz catheter with the balloon deflated
- Cardiac arrhythmias – if tip is in the RV can irritate myocardium and cause SVT, VT, Afib, ect
- Infection – similar to central line
- Pulmonary artery rupture – rare but deadly complication caused by overwedging Swan-Ganz catheter and rupturing the PA
ICU Medications
Vasopressors - Keep blood pressure up
Inotropes- augment CO/CI
Anti-HTN- keep blood pressure down
vasopressors include
Norepinephrine (levophed) - may cause arrhythmias or peripheral ischemia in higher doses
Phenylephrine (Neo-Synephrine) - bradycardia
Vasopressin (Pitressin) - may cause coronary constriction
Inotropes include
Dobutamine (Dobutrex) - may cause arrhythmias, worsening HCM
Epinephrine - Lactic acidosis
Milrinone - Hypotension, Arrhythmias, Headache renal function
Dopamine - may cause arrhythmias
Anti-HTN include
Esmolol (Brevibloc) - slows AV conduction -> bradycardia or heart block
Nicardipine (Cardene) - critical aortic stenosis
Nitroglycerin (Tridil) - Headache, increases ICP
Nitroprusside (Nipride) - cyanide accumulation, Kidney, liver
when is the only time we do not food pts in ICU
Only time we do not feed if in patient is in shock-> risk of bowel ischemi
when shoudl we start a feeding tube
- When there is inadequate nutrition for 3 days or there is a high risk of aspiration
- Do not start enteric feeds for patients in shock -> risk of ischemic bowel
complications of tube feeds
- Aspiration –can be reduced by having head of bed 30° or higher
- Diarrhea – very common with tube feeds, can change formula or add fiber
- Skin or mucosal damage
•Total Peripheral Nutrition (TPN)
- Indicated when enteral nitration is not possible
- Usually wait 5-7 days without nutrition prior to starting
- High complication risk – infection risk
- Needs central line, with a dedicated port
- Dose not prevent intestinal atrophy
before using NG tube what must you always do
confrim w/ CXR that the tube is in the correct place
•Ideal vent mode for for weaning
Pressure Support
- The patient’s TV and RR are not set, rather the patient receives assistance with each breath
- Patient needs to initiate the breath
•Used for patients with impending respiratory failure or who is struggling after extubation
Non-invasive ventilation: BiPAP
- BiPAP provides assistance with the mechanics of ventilating (regulating oxygen and carbon dioxide)
- Can adjust the inspiratory and expiratory pressures to achieve a desired TV
Advantages:
- Can prevent intubation
- Intermittent use
Disadvantages:
- Claustrophobic, patients tend not to tolerate it
- Patient’s can not eat or drink while mask is on
- Can dry up secretions and cause a mucus plug
- The clinician is setting the inspiratory pressure and inspiratory time
- The resulting TV depends on the set driving pressure, TV will be varied
Pressure Control
Each breath is given a set amount of pressure via the ventilation
•Advantages: Can have strict control over the airway pressure which can help with barotrauma and fresh suture lines
Disadvantages
- Can not wean from this mode
- Can be very uncomfortable
