Lung Mechanics and PIP Overview

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Questions and Answers

What is PIP?

Peak inspiratory pressure - highest pressure reached during inspiration, pressure used to deliver a set tidal volume.

What does PIP represent?

The pressure required to overcome airway resistance and inflate the lungs.

If the set tidal volume and set flow remain constant, what happens to the PIP?

It should remain constant unless there is a change in lung compliance or airway resistance.

What is lung compliance?

The condition of the chest wall and its ability to expand and hold air. Signup and view all the answers

What complications can occur that cause lung compliance to decrease?

Stiff lungs (ARDS, IPF), restrictive diseases (pneumonia, CHF, pleural effusion, pulmonary edema, fungal diseases), external compression of the lung. Signup and view all the answers

What is plateau pressure, and how is it acquired?

The pressure required to maintain a held breath in the lungs, acquired by an inspiratory hold maneuver using a ventilator. Signup and view all the answers

What does plateau pressure represent?

The condition of the lungs, but not the airways. Signup and view all the answers

What type of compliance is PIP used to calculate?

Dynamic compliance, because the measurement is taken while gas is in motion. Signup and view all the answers

What type of compliance is plateau pressure used to calculate?

Static compliance, because the measurement is taken while gas is in stasis. Signup and view all the answers

Between PIP and plateau pressure, which is always greater than the other?

PIP is always greater than plateau pressure. Signup and view all the answers

How do you get plateau pressure from a spontaneously breathing patient?

It is difficult if not impossible. Signup and view all the answers

How long are inspiratory pause maneuvers?

About 1 second. Signup and view all the answers

What kind of relationship does plateau pressure have with static compliance?

An inverse relationship. Signup and view all the answers

Patients with elevated plateau pressures may be difficult to bag. What can you do to counter this?

Use more PEEP (5+). Signup and view all the answers

How do you calculate static compliance?

(Exhaled tidal volume) divided by (plateau pressure - PEEP). Signup and view all the answers

How do you calculate dynamic compliance?

(Exhaled tidal volume) divided by (PIP - PEEP). Signup and view all the answers

What value can you calculate instead of dynamic compliance that would be more useful in assessing an increase in PIP?

Airway resistance. Signup and view all the answers

How do you estimate airway resistance? What is this also called?

PIP - Plateau Pressure; Transairway pressure. Signup and view all the answers

How do you calculate airway resistance?

(PIP - Plateau Pressure) divided by (Flow L/min divided by 60). Signup and view all the answers

If both PIP and plateau pressure are increasing at similar rates, what can you assume is the issue? Why?

Static compliance. If plateau pressure increases, the PIP will increase as well. Signup and view all the answers

If the PIP increases while the plateau remains the same, what does this tell you?

There is a problem with increased airway resistance. Signup and view all the answers

What does lung compliance tell you about the patient?

The condition of their lungs and whether or not they are getting better or worse throughout their stay at the hospital. Signup and view all the answers

What is airway resistance WNL?

0.6 - 2.4 cm H2O/L/sec (may increase to up to 6 for intubated patients). Signup and view all the answers

What is static compliance within normal limits?

60 - 100 mL/cm H2O. Signup and view all the answers

What are five factors that decrease static compliance? How can you treat it?

Atelectasis, pulmonary edema, pneumonia, ARDS, sepsis. Treat with PEEP and addressing the underlying cause. Signup and view all the answers

What are four factors that increase airway resistance? How can they be treated?

Bronchospasm (treated with beta agonist), secretions (treated with suctioning), kink in ETT (assess and replace if needed), foreign body aspiration (treated with bronchoscopy). Signup and view all the answers

Study Notes

PIP (Peak Inspiratory Pressure)

Indicates the highest pressure during lung inspiration.
Essential for delivering a set tidal volume to patients.

Significance of PIP

Represents the pressure needed to overcome airway resistance and inflate lungs.

PIP Constancy

Remains constant if tidal volume and flow are steady, unless lung compliance or airway resistance changes.

Lung Compliance

Reflects the chest wall’s ability to expand and retain air.

Complications Reducing Lung Compliance

Conditions include ARDS (Acute Respiratory Distress Syndrome), IPF (Idiopathic Pulmonary Fibrosis), pneumonia, CHF (Congestive Heart Failure), pleural effusion, pulmonary edema, and fungal diseases.
External lung compression also impacts compliance.

Plateau Pressure

Pressure used to maintain a breath in the lungs, measured via inspiratory hold on a ventilator.
Represents lung condition, excluding airway status.

Compliance Calculations

PIP is utilized for dynamic compliance calculations; measurements occur during gas motion.
Plateau pressure is associated with static compliance, measured during gas stasis.

Comparative Analysis of PIP and Plateau Pressure

PIP is consistently higher than plateau pressure.

Plateau Pressure Measurement in Spontaneously Breathing Patients

Difficult to obtain plateau pressure from non-ventilated patients.

Inspiratory Pause Duration

Typically lasts about 1 second during ventilator use.

Plateau Pressure and Static Compliance Relationship

Inverse correlation: if static compliance decreases, plateau pressure rises, indicating worsening lung conditions.

Elevated Plateau Pressure Management

Increase PEEP (Positive End-Expiratory Pressure) to facilitate bagging.

Static Compliance Calculation

Calculated as exhaled tidal volume divided by the difference between plateau pressure and PEEP.

Dynamic Compliance Calculation

Determined by exhaled tidal volume divided by the difference between PIP and PEEP.

Airway Resistance Assessment

More useful indicator for an increasing PIP value than dynamic compliance.
Airway resistance calculated by subtracting plateau pressure from PIP, also known as transairway pressure.

Airway Resistance Calculation

Determined as the difference between PIP and plateau pressure divided by flow (L/min divided by 60).

Issue Identification Through Pressure Measurements

If both PIP and plateau pressure rise at similar rates, lung static compliance is the main concern.
If PIP rises while plateau pressure remains stable, airway resistance is likely increased.

Lung Compliance Importance

Indicates patient’s lung condition and progress throughout hospital stay.

Airway Resistance Normal Values

Typical range is 0.6 - 2.4 cm H2O/L/sec; may rise to 6 for intubated patients.

Static Compliance Normal Limits

Falls within the range of 60 - 100 mL/cm H2O.

Factors Decreasing Static Compliance

Include atelectasis, pulmonary edema, pneumonia, ARDS, and sepsis.
Treated with PEEP and addressing underlying causes.

Factors Increasing Airway Resistance

Bronchospasm, secretions, kinking in endotracheal tube (ETT), and foreign body aspiration.
Managed with beta agonists, suctioning, catheter assessment for kinks, and bronchoscopy.

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Description

This quiz explores the concepts of Peak Inspiratory Pressure (PIP) and its significance in lung mechanics. You'll learn about factors influencing PIP, lung compliance, and complications affecting respiratory function. Test your understanding of these critical aspects of respiratory therapy.