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Respiratory Failure & Mechanical Ventilation

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62 years old female who was intubated for acute on chronic hypercapnic respiratory failure secondary to COPD exacerbation. Her ideal body weight is 67 Kg. CXR shows severely hyperinflated lungs.

Patient was placed on AC mode of ventilation with VT of 450 mL, RR of 22 per minute, and an inspiratory flow of 60 L/min. Her minute ventilation was 10 liters per minute.

Ibrahim Ameen
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Ventilator graphic of an intubated asthmatic patient on mechanical ventilation showing mild persistent flow at end of expiration indicating auto-PEEP:

The ventilator settings were changed as the following:

VT decreased from 470 to 420 mL.

Rate decreased from 20 to 16 breaths per minute but the patient is still breathing over.

The inspiratory time was decreased from 0.9 second to 0.6 second.

PRVC mode of ventilation with a targeted VT of 400, RR 26 and I:E ratio of 1:1.5. Notice the dynamic hyperinflation (autoPEEP) with persistent flow at end of expiration and the ineffective triggers.

Ventilator settings were adjusted to allow longer expiration by decreasing the rate to 20 per minute, and decreasing inspiratory time with I:E at 1:2.9. The volume was also increased to 450 ml.

Dynamic hyperinflation improved remarkably and now the ventilator is triggered with every inspiratory effort of the patient.

Ibrahim Ameen
Hussam Almasri
Osama BasHa

As you know, patients with severe asthma and status asthmaticus develop dynamic hyperinflation syndrome and autoPEEP meaning that the inhaled air does not get exhaled completely and the pressure is built up inside the alveoli. This is caused by not enough expiratory time due to the high time constant of the airways. My question, what will happen next if the process continues?

How does dynamic hyperinflation progress if no change in the expiratory time made on the ventilator?

  • 0%Continues to build till the lung ruptures

  • 0%Stops on its own due to increased driving pressure

  • 0%I do not know!

You may want to see this video to help you understand the concept.


47 years old female with status asthmatics who got intubated and placed on mechanical ventilation. An inspiratory hold was applied as shown in this snapshot of the ventilator screen:

Notice the limitation of the expiratory flow in the first breath before the inspiratory hold. Also notice that the peak pressure is elevated at 46 cm H2O, the plateau is elevated at 30 cm H2O and the difference is at 16 cm H2O representing the increased airway resistance due to bronchospasm.

Mouhmad Jamil

65 year-old male with acute respiratory failure secondary to pulmonary edema who was intubated and placed on mechanical ventilation. His course was complicated with left parietal occipital and temporal infarction. The following graphs have been observed;

Please identify the abnormality and answer the following question:

This patient-ventilator asynchrony is caused by:

  • 0%Early cycling

  • 0%Delayed cycling

  • 0%Flow asynchrony

  • 0%Malfunction

Ibrahim Ameen

Please notice the volume over time scalar as indicated by the light orange arrow and provide your feedback:


Please select your answer and you may provide your explanation in the comment section.

The noticed abnormality is caused by:

  • 0%Leak

  • 0%Auto-PEEP

  • 0%Malfunction


The respiratory drive is the intensity of the neural stimulus that determines how much the respiratory muscles contract. Excessive or low respiratory drive can be encountered in different clinical scenarios in patients on mechanical ventilation. High respiratory drive potentially leads to an injurious effect on the diaphragm (myotrauma), and on the lung (patient-self-inflicted lung injury). The low respiratory drive may cause disuse atrophy which leads to difficulty in weaning off the ventilator. Occlusion pressure at 100 ms (P 0.1) is the negative pressure measured 100 ms after the initiation of an inspiratory effort performed against a closed respiratory circuit and has been used as an indirect measure of the respiratory drive.

Please observe the P0.1 procedure and value in the. Above graph and provide your answer to this question:


Determinants of Effect of Extracorporeal CO2 Removal in Hypoxemic Respiratory Failure | NEJM Evidence

  • Ventilation strategy combining very low tidal volume (VT) with extracorporeal carbon dioxide removal (ECCO2R) is evaluated in patients with acute hypoxemic respiratory failure.

  • The effect of ECCO2R on mortality varies based on the ventilatory ratio (VR) and the severity of hypoxemia.

  • High VR (3 or higher) is associated with a higher probability of benefit and reduced mortality with the intervention.

  • Low VR (less than 3) is associated with a higher probability of increased mortality with the intervention.


There are two fundamental methods to control the delivery of a breath. The clinician can choose to keep either volume or pressure constant from breath to breath. The control variables most commonly used to describe modes of ventilation are volume-controlled (VC) ventilation and pressure-controlled (PC) ventilation. Within these two categories are multiple ways to tailor specific modes. In volume-controlled ventilator, clinician sets flow magnitude and pattern; the pressures used to deliver the set tidal volume will vary as a function of the patient’s pulmonary resistance and compliance and the his or her efforts in order to deliver that flow.

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