Respiratory failure and intubation Flashcards
Assist control settings:
RR: 14-18 breaths per minute
Tidal Volume 8-10 ml/kg IBW
FiO2: 100
PEEP: 5
Get portable CXR
ABG in 30 minutes
If pO2 is high
decrease FiO2
to prevent long term oxygen poisoning. Usually happens when FIO2>50.
If pO2 is low
increase PEEP we don’t like too high of PEEP at first because of high risk for barotrauma.
If pCO2 is high
increase RR or increase TV
If pCO2 low
decrease RR decrease TV increase sedation
mechanical ventilation indications
severe rspiratory failure
impaired sensorium GCS score of
hemodynamic instability
difficulty clearing secretions
Pulmonary weaning from ventilator includes
SBT for 2 hrs RSBI (rapid shallow breathing index) <105 Good mental status strong cough absent upper airway lesions (cuff leak and can lift head)
When to consider tracheostomy
after 10-14 days of being ventilator
ET tube should be inserted to average depth of:
20-21 cm in women and 22-23 cm in men.
after intubation should see:
symmetrical rise and both lungs should have bilateral breath sounds.
what happens if you see asymmetrical rise of chest after intubation
may have endobronchial intubation or right mainstem bronchus because of its more vertical orientation. will lead to eventual collapse of left lung. Tx is to pull back ET tube by 3 cm.
Don’t be fooled! Esophageal intubuation can have normal waveform at first in end tidal CO2 capnography so what do next
the normal waveform will occur in first few ventilations with esophageal intubation and then flatline. Will need to reintubate the patient.
non invasive positive pressure ventilation indications (strongest evidence)
COPD (severe exacerbation or prevent extubation failure)
cardiogenic pulmonary edema
acute respiratory failure
- post operative hypoxemic respiratory failure
immunosuppressed pts
- facilitate early extubation
Contraindications to non invasive positive pressure ventilation
Medical instability (cardiac or respiratory distress, severe acidosis ph<7.1, non respiratory organ failure (unstable cardiac arrhythmia/hemodynamic instablility, GCS<10 or GI bleed. Also contraindicated in inability to protect airway (uncooperative or agitated, inability to clear secretions or aspiration risk mechanical issues - recent esophageal anastomosis, facial or neurological surgery, deformity or trauma upper airway obstruction
ARDS ventilator set up
mode: volume assist control tidal volume:
initially 8ml/kg IBW
Reduce to 4-6 ml/kg over 1-3 hrs
PEEP is 5-15 cm and use high
PEEP for moderate to severe ARDS
Resp Rate: <35/min
goal pH >7.2
PaO2/SaO2 55-80mg / 88-95%
ARDS plateau pressure goal
<30 cm H20
what works better low or high PEEP in ARDS
greater improvements in oxygenation with higher levels of PEEP without no difference in mortality between the two groups. the greater PEEP opens collapsed alveoli and spreads out tidal volume over more alveoli which decreases overall alveoli distension, and this allows for less barotrauma to alveoli since there’s cyclical atelectasis.
ideal position of ET tube is
2-6 cm from carina to allow for migration of head movement when neck is flexed the end of ET tube migrates towards carina.
treatment for moderate to severe COPD exacerbation with hypercapnic acidosis
NPPV or non invasive positive pressure ventilation can help decrease resp acidosis, tx failure, mortality and length of hospital stay
how long should someone be on NPPV and when should you escalate to intubation?
2 hrs. if doesn’t improve or worsens needs intubation and mechanical ventilation.
criteria for ARDS
1 new or worsening respiratory symptoms during past week or within 1 week of known clinical insult
2 bilateral lung opacities - fluffy infiltrates that look like pulm edema
3 no signs of cardiac failure or fluid overload
4 Severity of hypoxemia defined by P/F ratio <300 with a PEEP >5
ARDS severity of hypoxemia as defined by
PaO2/FiO2 ratio <300 mmHG with PEEP>5 cm H20
mild ARDS: 200-300 mmHG
moderate: PF 100-200 mmHG
severe: PF< 100 mmHG
goal PaO2 for ARDS
55-80 mm Hg
why do we like low tidal volumes
6 ml/kg of IBW. Preferred compared to high tidal volume because it can cause over distension, alveolar rupture and gross barotrauma decreases mortality and number of ventilator days.
what helps to improve mortality in ARDS
early administration of neuromuscular blockers and prone positioning.
goal plateau pressure in ARDS
<30 cm H20
which pts should not have low tidal volumes or hypercapnia or respiratory acidosis?
those with increased ICP, cerebral edema, or seizure disorder.
Do we allow for permissive hypercapnia in ARDS?
yes as long as pH >7.20 because this means we can have less barotrauma as there’s lower tidal volume ventilation (aim for 4-6 ml/Kg of idea body weight) and so this allows for lower plateau pressure.
how to reduce risk for oxygen toxicity?
try to lower FIO2 when able to <60%.
PEEP is divided into
extrinsic and intrinsic components
extrinsic is provided by ventilator
intrinsic is component of air that remains in lungs due to incomplete expiration (auto peep)
who is at greater risk for autoPEEP?
those are those who are unable to complete exhalation before the start of next inspiratory cycle. This occurs over repeated breaths and end expiratory alveolar pressure rises above the extrinsic PEEP and results in auto PEEP
how to correct for auto PEEP?
reduce minute ventilation (reduction in tidal volume or respiratory rate) increasing expiratory time (using bronchodilators and inhaled corticosteroids to relieve airway obstruction)
visualization of PEEP and autoPEEP on pressure and flow
Paw= airway pressure Palv = alveolar pressure PEEP= positive end expiratory pressure
criteria for extubation failure
extubation failure is about 12-15% normally and if you have lower extubation rates you may need to try to extubate more people.
extubation failure is associated with
increased hospital mortality, increased risk of nosocomial pneumonia, and longer ICU stays and total hospital stays.
Fluid management in ARDs:
aim for a target of CVP<4mm and pulmonary artery occlusion pressure <8 mmHg
Pulmonary edema can develop easily in ARDs at any given hydrostatic pressure because the quality of intravascular hydrostatic pressure as oncotic pressure is unable to retain fluid in the capillaries.
Fluid restriction therefore can decrease risk fo developing pulmonary edema
Conservative management improves oxygenation index and lung injury score (PaO1/FiO2) ratio and resulted in fewer days on the ventilator or ICU.
how to treat a patient is in pain while ventilated?
see them over breathing, see grimacing, agitation, writhing or signs of sympathetic activation with tachycardia, hypertension, and tachypnea - see overbreathing the vent with resp alkalosis.
Give adequate pain control with IV opioids like fentanyl, hydromorphone, or morhpine to decrease physiological responses to pain (hypermetabolism, increased catabolism, and oxygen demand)
while intubated and on ventilator, causes of
Increased peak pressure and NORMAL plateau pressure:
Increased peak pressure and INCREASED plateau pressure:
peak airway pressure definition:
maximum pressure measured in tidal volume that is being delivered. Try to keep peak pressure <35 cm H2O prevent risk of barotrauma.
Equals the sum of resistive pressure (flow X resistance) and plateau pressure
Peak airway pressure = resistive pressure + plateau pressure
Peak pressures are dynamic pressures that measure resistance of flow of air delivered from ventilator and the amount of pressure to needed to inflate lung.
plateau pressure definition
plateau pressure is the pressure measured during an inspiratory hold maneuver, when pulmonary airflow and therefore resistive pressure are both 0. Keep plateau pressure <30 cm H2O to prevent barotrauma.
Plateau pressure equals sum of elastic pressure (elastance X tidal volume) and positive end expiratory pressure
Plateau pressure = elastic pressure + PEEP
Plateau pressures are static lung pressures that give an estimate of lung compliance
peak pressure equation
Equals the sum of resistive pressure (flow X resistance) and plateau pressure
Peak airway pressure = resistive pressure + plateau pressure
what to we try to keep peak pressures below:
Try to keep <35 cm H2O to prevent barotrauma
Equals the sum of resistive pressure (flow X resistance) and plateau pressure
Peak airway pressure = resistive pressure + plateau pressure
equation for plateau pressure
Plateau pressure equals sum of elastic pressure (elastance X tidal volume) and positive end expiratory pressure
Plateau pressure = elastic pressure + PEEP
ideal plateau pressure should be below
Keep plateau pressure <30 cm H2O to prevent barotrauma.
how are elastance aned compliance related?
inversely related so decreased compliance (pulmonary fibrosis) will have stiffer lungs and higher elastic pressure
increased peak pressure with unchanged plateau pressure means that
there’s increased airway resistance without change in lung compliance.
This means increased flow resistance from either: mucus plug, biting the tube, or bronchospasm
Treatment of mucus plug
increased suctioning
increased peak pressure and increased plateau pressure in a ventilated pt means:
this means there’s higher overal pressure in the closed system with the higher normal peak airway pressure
The higher overall plateau pressure may from increased elastic pressure or decreased compliance of the lung from either a pneumothorax, pulmonary edema, pneumonia, atelectasis or right mainstem intubation.
benefit of non invasive positive pressure ventilation in heart failure?
NPPV increases intrathoracic pressure and reduces venous return and decreases right and left ventricular preload and improves cardiac output with the Frank Starling relationship.
It helps with cardiogenic pulmonary edema because of the increased preload from the reduced LV function and increased LV filling pressures and left atrial pressure (preload is increased) and these elevated pressures are eventually transmitted to the pulmonary capillaries that leads to fluid transudation.
laryngospasm after thyroidectomy is a
What causes this?
is a medcial emergency
stridor after thyroidectomy plays a clue to cause
if respiratory distress or stridor is apparent after extubation then there’s bilateral recurrent laryngeal nerve injury
If stridor appears within a few hours of surgery it’s probably a wound hematoma with tracheal compression. Need to remove the bandages and look.
If stridor appears even lader and preceded by paresthesias and muscle cramps then its likely hypoglycemia from transient hypoparathroidism or inadavertent parathyroidectomy
what is tracheomalacia?
diffuse or segmental tracheal weakness,
presents with dypsnea, cough, increased sputum production, wheezing, and stridor.
what causes tracheomalacia?
prolonged intubation, chest wall trauma, severe emphysema, compression from a lesion
what is the RSBI is rapid shallow breathing index
and how is it calculated and what is its role in determining if someone can be extubated?
intubated pt is breating RR 28 and tidal volume is 200 ml
RSBI is rapid shallow breathing index and if this ratio is <105 will be ok to extubate
it’s calculated by the Respiratory Rate / tidal volume
28/ 200 ml in LITERS or 28/0.2 = 140 which is too high. Probably will fail extubation. Needs to remain on assist control
tracheostomy indications
long term mechanical ventilation -can’t remain intubated for >14 days. generally done after 11 days internationally
weaning failure
upper airway obstruction
copious secretions.
Goals for ARDS:
low tidal volume 4-6 cm3
ok for permissive pCO2 as long as pH>7.2
pO2>55
Peak pressure <30
how to determine if someone is brain dead?
Prior to the bedside apnea test, they are pre-oxygenated with 100% oxygen for 10 minutes using exisitng ventilatory support and then mechanical ventilation is discontinued.
Then they are observed for spontaneous respirations for 10 minutes. if respirations are observed then apnea test is negative and pt is not brain dead.
pt must be HDS, body temp >36 C and normal pH and normal PaCO2/PaO2 levels.
Apnea testing objectively confirms brainstem failure if pt cannot generate sponataneous breaths or trigger the ventilator in response to PaCO2 >10 minutes after disabling control mode.
