Ventilation: Basic Principles

Ventilation: Basic Principles

Jamie Ranse

Registered Nurse

Emergency Department

The Canberra Hospital

• Introduction to Ventilation Principles

• Respiratory Anatomy and Physiology

• Indications for Ventilation

• Modes of Ventilation

• Patient Management

• Complications

• Questions

Overview

• Ventilation is the movement of air into and out of the alveoli.

Introduction

Hudak, et al, 1997, Critical Care Nursing: A Holistic Approach (7th Edn), Lippincott, Philadelphia, USA

Mechanics of Ventilation:

• Elasticity

• Compliance

• Resistance

• Pressure

• Gravity

Introduction


• Respiratory Structures

• Respiratory Zones

• Partitioning of Respiratory Pressures

• Boyles Law

• Respiratory Volumes and Capacity

• Ventilation and Perfusion

Anatomy and Physiology


Porth CM, 1998, Pathophysiology (5th Edn), Lippincott, Philadelphia, USA

Respiratory Structures



Respiratory Zones



Partitioning of Respiratory Pressures



Boyles LawIncrease V = Decreased P

Decreased V = Increased P



Boyles Law

• Air flows from a region of higher pressure to a region of lower pressure.

• To initiate a breath, airflow into the lungs must be precipitated by a drop in alveolar pressures.



Respiratory Volumes and Capacity


perfusion without ventilation = shunt

normal ventilation and perfusion

ventilation without perfusion = dead space

airway

venous blood arterial blood


Ventilation

and

Perfusion

• Airway Compromise (potential)

• Respiratory Failure– pH: <7.25

– PaCO2: >50 mmHg

– PaO2: <50 mmHg

• Increased Work of Breathing

• Head Injury Management

Indications for Ventilation


• Support though illness• Reversal of hypoxemia• Reversal of acute respiratory acidosis• Relief of respiratory distress• Resting of the ventilatory muscles• Decrease in oxygen consumption• Reduction in intracranial pressures• Stabilisation of the chest wall

Objective of Ventilation


• freq

• Vt

• MV

• I:E ratio

• Trigger

• Ramp

Modes of Ventilation

Diepenbrock NH, 1999, Quick Reference to Critical Care, Lippincott, Philadelphia, USA: P166.

• Pmax

• Paw

• fspn

• MVspn

• PEEP

• Controlled – Pressure Control (PC)– Volume Control (VC)

• Supported– Continuous Positive Airway Pressure (CPAP) – Pressure Support (PS)

• Combined– SIMV (PC) + PS– SIMV (VC) + PS

Modes of Ventilation

Diepenbrock NH, 1999, Quick Reference to Critical Care, Lippincott, Philadelphia, USA: P166.

Modes of Ventilation: Control

Controlled Mechanical Ventilation:

• The Minute Volume is determined by the ventilator

• The patient has no option to override the ventilator


Pressure Control:

• A preset peak inspiratory pressure is delivered to the patient at a preset respiratory rate

• Volume is not preset and is determined by the mechanics of ventilation.

(elasticity, compliance, resistance, pressure, gravity)


Volume Control:

• A preset tidal volume is delivered at a present respiratory rate

• 7 – 10 mls/kg 50kg = 350 – 500mls

70kg = 490 – 700mls

90kg = 630 – 900mls

Modes of Ventilation: Support

Continuous Positive Airway Pressure:

• A spontaneous breathing mode, where the patient generates their own breath

• The ventilator maintains a constant positive pressure on expiration (PEEP)

• Aims to increase Functional Residual Capacity

Modes of Ventilation: Support

Pressure Support:

• A spontaneous breathing mode

• Need for additional support to achieve optimal tidal volumes

• Ventilator delivers a constant preset pressure on inspiration

CPAP + PS = BiPAP

Modes of Ventilation: Combined

Synchronised Intermitted Mandatory Ventilation:

• Similar to IMV

• If the patient initiates a breath and the ventilator synchronises so the ventilator doesn’t deliver a breath at the same time

Modes of Ventilation: Combined

SIMV (PC) + PS:

• Pressure controlled ventilation with pressure support on spontaneous breaths

SIMV (VC) + PS:

• Volume controlled ventilation with pressure support on spontaneous breaths

SIMV (VC) + PS

Freq: 10

Vt: 500

(MV = 5.0)

PEEP: 5

PS: 10

• Monitoring

• Suctioning

• Other– Sedation– Positioning– Oral and Eye Care

Patient Management

• ECG

• SpO2

• ETCO2

• Alarm limits• Air Entry / Work of Breathing• Ventilator observations and alarm limits• Full assessment

Patient Management:Monitoring

• PRN– Increasing airway pressures

– Decreasing SpO2

– Increased work of breathing

• Pre-oxygenate (100% oxygen)

• Less than 15 Seconds

Patient Management:Suctioning

Patient Management:Other

• Sedation– Propofol, Morphine and Midazolam

• Positioning– 2/24

• Oral and eye care– 2/24

• Airway– Aspiration, decreased clearance of secretions,

predisposition to infection

• Endotracheal Tube– Tube kinking, sputum plug, right main bronchus

intubation, tube migration, cuff failure, laryngeal oedema

• Mechanical– Ventilator malfunction, hypoventilation,

hyperventilation, barotrauma, pneumothorax

Complications

Questions

Ventilation: Basic Principles

Jamie Ranse

Registered Nurse

Emergency Department

The Canberra Hospital

Ventilation: Basic Principles

Health & Medicine

Transcript of Ventilation: Basic Principles