Chapter 4 - Establishing the Need for Establishing Mechanical Ventilation Flashcards
What are the 3 definitions of ARF?
- Inability to maintain adequate O2 uptake (PaO2 or CaO2)
- Inability to adequately eliminate CO2
- Inability to maintain acceptable ABG’s
What are the 2 types of ARF?
Type 1 - Hypoxemic
Type 2 - Hypercarbic w/ some Hypoxemia
Causes of Hypoxic Lung Failure
- Serious V/Q mismatching
- Diffusion defects
- R to L shunt
- Alveolar Hypoventilation
Hypoxic Lung Failure Treatments
- Oxgen Therapy and/or CPAP
- Intubation
What is a “Regular” Shunt?
Some blood is going to areas that are under ventilated
What is a “True” Shunt?
NO ventilation where blood is going near a ventilator unit
What is Refractory Hypoxemia?
When there is no response to an increase of oxygen
Causes of Hypercapnic Respiratory Failure
- Ventilator Pump Failure (Resp. Muscles, Thoracic Cage, Nerves)
- Disorders (CNS, NMD, Disorders that increase WOB)
Hypercapnic Respiratory Failure Treatments
- NIPPV
- Intubation
In which type does Diaphoresis occurs?
Type II
What occurs during Hypoxia?
-Tachycardia and Tachypnea
What occurs during Hypercapnia
- Increased CO2
- Increased cerebral blood flow
- High levels of CO2 leading to CO2 narcosis
What does a Traumatic Brain Injury cause within the first 24 hours?
Reduction of blood flow to the brain by 50%
If patient is hyperventilating with a brain injury, what occurs?
Blood flow is reduced by another 50%.
75% total blood flow is cut off.
What is our target CO2 range for TBI patients?
35-45 but no less than 30 mmhg
What is given to reduce ICP for head injuries?
Osmotic diuretic (Mannitol)
Why do we not hyperventilate patients with TBI for more than 24 hours?
Reflex will go away and the ICP will go back up
If an ICP > 20 is sustained for 5 min, what can we do?
We can temporarily hyperventilate a patient between 30-35
What drugs impair neuromuscular function?
All Narcotics
What is a normal MIF and what is considered bad?
- Normal: -80 cmH20
- Bad: > -20 cm h20
What is a normal VC?
60-80 mL/kg
What is the VO2 percentage with normal WOB?
~1-4%
What are evidences of increased WOB?
- Increased RR and/or depth of respirations
- VO2 increases to 35-40%
What is the Normal and Critical values for MIF?
Normal: -100 to -50 cmH20
Critical: -20 to 0 cmH20
What is the Normal and Critical values for VC?
Normal: 65-75 mL/Kg
Critical: > 10ml per kg
What is the Normal and Critical values for Vt?
Normal: 4-8 mL/Kg
Critical:
What is the Normal and Critical values for RR?
Normal: 12-20/min
Critical: >35/min
What is the Normal and Critical values for PEFR?
Normal: 350-600L/min
Critical: 75-100L/min
What is the Normal and Critical values for VD/Vt?
Normal: .3-.4
Critical: .6
What are the standard criteria for Invasive Ventilation?
Normal Criteria: Support of pulmonary system until return to normal state, Reduce WOB, Restore Acid-Base balance, Improve O2 delivery.
What are the alternatives to Invasive Ventilation/
Supplemental O2: High Flow
Treatment of underlying cause
NIPPV
CPAP via T-piece
What are the Absolute contraindications for NIPPV?
Absolute: Cardio-Resp. Arrest, Acute instability of other organs, Upper airway obstruction, Inability to protect airway, Inability to clear secretions, Facial/Head trauma
What are the Relative contraindications for NIPPV?
Relative: Cardio-Pulmonary Instability, Inability to cooperate, copious secretions, Extreme obesity
What ABG values are associated with respiratory failure?
pH less than 7.25
paC02 50 mmhg and rising
PaO2 less than 90% of predicted.
How do you assess if a patient has an oxygenation problem?
Calculate the predicted PaO2.
Pa02 = 104.2 - (0.27 x age)
After that, if the Patient’s ABG is less than 90% of predicted. Its an oxygenation problem.
What are causes of Hypoxemic (Type I) respiratory failure?
5 causes
Serious V/Q Mismatching
Diffusion Defects
Right to Left Shunt (Not a true shunt because some blood goes through the pulmonary arteries)
Alveolar Hypoventilation
What are causes of Hypercapnic (Type II) Respiratory Failure?
2 main causes
Ventilatory Pump Failure
(Respiratory Muscles, Thoracic Cage, Nerves and Nerve Centers That Control Ventilation)
Disorders Leading To Ventilatory Pump Failure
(CNS Disorders, Neuromuscular Disorders, Disorders That Increase WOB)
What are signs and symptoms of Hypercapnia?
Increased CO2 levels - Hypercapnia
Increased cerebral blood flow/vasodilation – headaches
High levels of CO2 leading to CO2 narcosis
Untreated could lead to acidosis – arrhythmias – death
What is the mantra for spinal cord injuries? why?
C 3,4,5 keep your patient alive.
C3 injuries have loss of respiratory muscles
C4 and C5 injuries have the possibility of loss of voluntary muscles for respiration.
What is the protocol for patients with a traumatic brain injury in the first 24 hours?
Never hyperventilate in the first 24 hours
If patient is becoming hypercapnic,
place patient in a Phentobarbitol coma and paralytics to decrease o2 comsumption
what is the ABSOLUTE criteria for invasive ventilation?
Apnea,
Acute Vent. Failure,
Impending Vent. Failure,
Refractory Hypoxemia
What is the formula for Mean Arterial Pressure?
What value are you looking for?
(2 diastolic + 1 Systolic)/3 = MAP
You want Map above 60 (low is deceased blood supply to organs)
High MAP is increased Cardiac Work Load
