Esophageal Pressure Monitoring

Question 1

Esophageal Pressure Monitoring in a Nutshell

Answer 1

Using Transpulmonary Pressures to Guide Ventilation

Question 2

Airway Pressure (Paw)

Answer 2

Paw=Ptp - Ppl

Reflects pressure required to inflate both the lungs and the chest wall

Question 3

Paw Measured

Answer 3

Plateau pressure during inspiratory pause

Total PEEP during an expiratory

So Paw = Palv during pause maneuvers because there is no flow

Question 4

When does pleural pressure =atmospheric pressure

Answer 4

There is two times when the pleural pressure=atmospheric pressure

Airway opening

Mouth pressure

These two times are when esophageal balloon pressure is measuring

Question 5

Lung Protective Ventilation

Answer 5

Target VT 4-6 mL/kg

Keep airway plateau pressure < 30 cmH2O

Set PEEP according to ARDSnet tables

This approach assumes pleural pressure is negligible

Question 6

Pleural Pressure (Ppl)

Answer 6

Reflects the pressure in the pleural space

Question 7

Pleural Pressure (Ppl) Affected By

Answer 7

Affected by an increase intra-abdominal pressure or a decreased chest wall compliance

Question 8

Pleural Pressure Measured

Answer 8

Can be estimated through esophageal pressure monitoring

To measure pleural pressure is a contentious point. It is thought to be pressure in the chest but not in the lungs, so if we can pass a catheter in the chest but not in the lungs we can measure the pleural pressure which is the though process behind esophageal pressure

Question 9

What Will Increase Pleural Pressure

Answer 9

Obesity

Ascites

Ileus

Bowel Edema

Post Fluid Resuscitation edema of abdominal tissues

Nearly 30% of patients admitted to ICU have an abnormally high intra-abdominal pressure which leads to increased chest wall elastance”

Question 10

Determining Transpulmonary Pressure

Answer 10

Requires measurement of esophageal pressures via an esophageal balloon

Pe is thought to reflect Ppl- No solid evidence base to support this yet

Question 11

What is the Esophageal pressure balloon measuring

Answer 11

It is measuring the pressure in the thorax cavity and then from there you can subtract that from the pressure that the ventilator is giving you because that is the pressure in the thorax cavity as well as the lungs

Question 12

Calculating Ptp

Answer 12

Ptp = Paw – Pe

Question 13

Inserting the esophageal balloon monitor

Answer 13

Insert to 60 cm…pull back to 40 cm. Should see cardiac oscillations

Can push on belly as a check to see temp spike in pressure

Smallest catheter is 6 Fr

Question 14

Performing an Esophageal Pressure Monitoring

Answer 14

Perform and inspiratory hold and determine what you Ptp is, we do this in order to make sure that we are ventilating the lungs at a safe pressure (<30 cmH2O)

Then perform an expiratory pause to see if Ptp is positive which is recommended in order to maintain recruitment of alveoli

Question 15

How Common is Intra-Abdominal Pressure

Answer 15

>12 mmHg-58.8%

>15 mmHg-28.9%

>20 mmHg-8.2%

Question 16

Increase Pleural Pressure

Answer 16

Increased pleural pressure (and thus a decreased Ptp) are caused by both an increase in intra-abdominal pressure anda decrease in chest wall compliance!

Question 17

bladder pressure and abdominal pressure

Answer 17

bladder pressure and abdominal pressure are correlated but can’t predict. If see an increase in bladder pressure than it is a red flag.

Question 18

Delta Ptp

Answer 18

Measurement of lung stress

Ptp = Ptpplateau- PtpPEEP

Lung stress = k x strain

K = 13.5 cmH2O = a constant for specific lung elastance

Lung strain = Ptp ÷ 13.5

Lung strain of 2 is considered lethal! (A Ptp of 20 cmH2O)