Quizzes

• Reverse trigger is present in all breaths: Esophageal swing happens after the machine triggered breaths
• Early cycle is present in every breath as expiration happens while the patient is still breathing
• Work shifting is present in every breath as the esophageal pressure goes down from 10 to the -ve in each breath
• Delayed cycling is not present in any breaths

https://www.journalmechanicalventilation.com/bridging-the-gap-enhancing-synchrony-in-mechanical-ventilation/

Chest Wall Compliance = Tidal Volume / End Insp Esophageal Pressure - End Exp Esophageal Pressure

https://www.journalmechanicalventilation.com/can-you-calculate-the-total-respiratory-lung-and-chest-wall-respiratory-mechanics-2/

In this figure, the end expiratory trans-pulmonary pressure is about -5 cmH2O which can cause atelectasis and atelectatrauma, keeping the end expiratory pressure around zero +/- 2 might mitigate atelectrauma

https://www.journalmechanicalventilation.com/mechanical-ventilation-review-part-1/

A: Expiratory Time Constant: about 0.7 seconds

B: Expiratory Time Constant: about 0.2 seconds

C: Expiratory Time Constant: about 1.8 seconds

https://www.journalmechanicalventilation.com/mechanical-ventilation-review-part-1/

This patient has elevated End tidal CO2 (PeCO2 normal about 35 mmHg) and elevated Volume of CO2 eliminated/minute (VCO2 normal 2.5-3 ml/kg/min) indicate increased production of CO2, all listed options can cause this except severe hypothyroidism as it causes decreased metabolism and thus VC02

The low inflection point or the airway closure point (red triangle) is about 11, also the maximum hysteresis (difference in volume between the inspiratory and expiratory tidal volume)

Hysteresis 

A: Stress Index of 1, PEEP ok

B: Stress Index > 1, Need to reduce PEEP for hyperdistention

C: Stress Index < 1, Need to increase PEEP for atelectasis

Stress Index

Alveolar Mechanics

PMI is the difference between the peak pressure (after the inspiratory pause) - the plateau pressure (Pressure support + PEEP)

https://www.journalmechanicalventilation.com/estimation-of-inspiratory-muscle-effort-using-three-common-indices-in-various-respiratory-models-a-bench-study/

Total respiratory compliance
= VT / Paw - PEEP Total

Total respiratory resistance
= PPIP - Pplat / V’

Chest wall compliance
= VT / End inspiratory Pes - End expiratory Pes

Chest wall resistance
= Peak Pes - End inspiratory Pes / V’

Lung compliance
= VT / End inspiratory PPL - End expiratory PPL

Lung resistance
= Peak PPL - End inspiratory PPL / V’

https://www.journalmechanicalventilation.com/can-you-calculate-the-total-respiratory-lung-and-chest-wall-respiratory-mechanics-2/

Patient-Ventilator Dyssynchronies

Patient-Ventilator Dyssynchronies

Patient-Ventilator Dyysynchronies