Effects of mechanical ventilation part II

what can a pneumothorax cause

Rapidly becomes a tension pneumothorax on the ventilator
1. Lung compression causes massive atelectasis, intrapulmonary shunting, and
hypoxemia
2. Compression of major blood vessels causes severe decrease in venous return and cardiac output

normal urine output

<400ml/24hrs

normal BUN

10 - 20 mg/dl

nromal creatine

.7 - 1.5

normal potassium

3 - 5

normal sodium

138 - 142

what increases/decreases with decreased renal function due to PPV

decreased urine output (<400ml/24hrs)

decreased Sodium (NA) 138 – 142 mEq/L

increased BUN (Blood Urea Nitrogen’s) 10 –20 mg/Dl
Increased Creatinine Levels (.7 to 1.5mg/Dl)
Increased Potassium (K) 3 –5 mEq/L

signs of GI bleeding and liver dysfunction

a. Increased prothrombin time >4sec
b. Increased bilirubin levels > 50mg/L
c. Decreased albumin < 20g/L
*Drugs that rely on liver perfusion to eliminate them, will have a prolonged effect on the patient due to decreased drug clearance*

how to prevent barotrauma in pts with ARDS

To avoid barotrauma in the ARDS patient, smaller tidal volumes, higher FIO2s, lower PaO2s, and higher PaCO2s ("permissive hypercapnia) are recommended

what are the specific targets in treating Acute Severe Lung Injury

PaO2

PaCO2

PEEP

Pplateau

VT

FIO2

I/E

PaO2 = 55 mm Hg or more
PaCO2 > 60 mm Hg
allow gradual increase buffer acid if pH < 7.25
PEEP = 10-15 cm H2O
Pplateau < 35-40 cm H2O
VT < 10 ml/kg
FIO2 = 0.80 or less
I/E ratio up to 1:1,
if no eauto-PEEP, may increase to 1.5:1

Hazards of Oxygen

A. Oxygen induced hypoventilation
B. Absorption atelectasis
C. Oxygen toxicity (use PEEP for FIO2 > 0.50)

autoPEEP mostly occurs in which kinds of pts

1. Obstructive airways disease
2. ARDS, burns, etc. requiring VE > 15-20 LPM
3. Small diameter tracheal tube

how to minimize autopeep

1. Minimizing RAW (bronchodilator therapy, suctioning, larger ETT)
2. Maximize E time
a. Increase flow to 80-100 LPM

b. Replace standard vent. circuit with low compressible volume circuit (decreases total VT delivered by ventilator thereby decreasing TI and increasing TE)
3. In COPD patient, add PEEP at or below auto-PEEP level to reduce WOB (withdraw this PEEP as auto-PEEP decreases).
4. Decrease minute volume if possible (allow PaCO2 to rise as along as pH > 7.30)

good lung up or down

good lung down

how to treat decreased CO

Treat with IV fluid therapy and ventilator maneuvers which decrease mean airway pressure