Tips for Respiratory Test

Here are some post conference concepts from M. Antaran.
This post is still under construction. I am typing these notes from my palmpilot recording. I will remove this comment when I have finished. So check back later.
ABG interpretations
4 points each x5 = 20
Level of hypoxemia or oxygenation (it might be normal)
Acid-base state-normal or (acidosis, alkalosis, respiratory, metabolic)
Is there compensation? if so.... partial or full

Mechanical ventilation
Used for alveolar ventilation (volume), which is the first process of the respiratory process.
Aids in the respiratory process but does not replace or complete it.
It is for (hopefully) giving adequate tidal volume at an adequate rate.

The most important Nursing consideration when Pt is artificially ventilated = ET tube placement
1. Listen for equal breath in both lungs. (If tube in too far, will ventilate R main stem only)
2. Tape the tube in place (chart ex. intubated 23 cm at the gumline) End of tube should be at least 2 "above the carina
If ETT touches carina, will cause pt to cough creating a neg pressure which works against the vent = barotrauma
If pt coughs = need Sx, obstruction, or tube touching carina

Barotrauma = oposing pressures in the thorax, pt coughs = membrane rupture = pneumothorax (sedate pt to prevent)
Volutrauma = hyperventilated too much, increased Tidal Volume, increased pleural pressure, alveoli pop = pneumothorax = hypoventilation
Anterior chest tube - for air
Lateral / posterior chest tube - for whatever is in the bases = fluids/blood
Can have combo pneumo/hemo thorax with barotrauma

Normal breathing with neg pressure generated in thorax
Vent = positive pressure (has to overcome built-in airway pressure = PIP or PAP not POOP
Peak Inspiratory Pressure or Peak Airway Pressure
Non compliant (stiff) lungs = high pressure = high PIP tells us pts lungs are not compliant and atelectatic
Normal PIP 20cm of H20 pressure
A high PIP = higher pressure needed to drive oxygen into the lungs to inflate the alveoli. Could see 40- 70 even (my ARDS pt was at 47)
PIP = the mean pressure that is in the airway
Bronchspasms and mucus plugs = higher PIP
PEEP = driving expiratory pressure to keep alveoli inflated
Pressure Support = driving inspiratory pressure to overcome the PIP and inflate the alveoli
On test could see.... On this pt the PIP is... (high, low, whatever)....

(The case study could be chest trauma)
Laceration or puncture = diffusion defect
Bronchospasm or mucus plugs = V/Q problems
Pneumothorax or hemothorax = hypoventilation problem
Cardiac output problems or obstruction by pulmonary emboli = High V/Q
Bilat Pneumonia with difuse infiltrates = Pysiologic shunt

Know the difference of the 4 types of hypoxemia
hypoventilation vs diffusion defect
V/Q imbalance vs physiologic shunt

4 Basic Vent Modes to know
FIO2 important
FIO2 driven by the PO2 desired
If PO2 is not at least 60 - will give higher FIO2 to get it higher
When blood gas is not known, will start vent at 40%
50% or higher creates O2 radicals
Resp Rate is driven by the PCO2
Tidal Volume (Vt) = the gas volume per breath - tend to stay (max) on the vent at 6-8cc/kg/breath
How we are assisting ventilation (Mode) PRVC, SIMV, IMV and AC
2 types of ventilators = pressure regulated and volume regulated
PRVC = pressure regulated volume control = combines a built in pressure to drive in the volume and pt does not get less than the volume that is dialed.
Adult lungs reach max volume size at age 25. Do not want to hypoventilate alveoli, volume based on the pt weight. Alveolar hypoventilation = hypoxemia
Children or pt with restrictive lung disease (ARDS)
Obstructive = low V/Q = obstruction in the airway - hypoxemia - have to overcome the pressure in the airway (COPD)
Asthma = restrictive - lose alveolar walls - bulla formed - component of COPD
Asthma - bronchitis - frequent pneumonia - secondary component of COPD
The PIP of bronchitis is the cause of the obstructive tendancy
Main Tx of obstructive tendancies is bronchodilation - to decrease the pulmonary vascular resistance
Restrictive - restriction in the lower airway
Obstructive - main problem in upper ariway
Restrictive - repeated pneumonia - loss of alveoli = diffusion defect - from surface area restriction
Restrictive - dont give too much Vt or lungs will 'pop' more
ARDS = diffused pneumonia - starts with (CXR) patchy consolidations throughout fields = diffusion defect
ARDS Syndrome - Initial insult - Histamine activation + biochemical mediators + O2 radicals = alveolar wall damage - significant atelectasis - white out in lung on CXR
Understanding this, will help understanding of the type of mode needed on the Vent
SIMV- Synchronized Intermittent Mandatory Ventilation - Good for weaning off vent.
Mandatory ventillation is rate given to pt.
Sensitive to pt's own respiratory drive. If rate set low, pt's central and peripheral chemo receptors will sense increasing CO2 and low O2 levels and cause pt to breath in addition to mandatory rate. Pt initiating own breaths is good indicator that the energy is available to start weaning from machine. Wise to put pt on SIMV right awayto get them back off ASAP.
IMV
AC - Rate and volume are mandatory (regardless of what pt tries to do) but pt could add to that and the vent would deliver preset volume.
Problem with this is if pt starts to increase rate to Ex. 30 breaths per minute and vent delivers preset volume of 550, pts lung will 'pop', Barotrauma. Sedate pt. This mode not used much,
To be continued.......