Lecture 1 Mechanical Ventilation an Introduction

8/11/2019 Lecture 1 Mechanical Ventilation an Introduction

1/20

BASIC MECHANICAL

VENTILATION COURSE

LECTURE 1

MECHANICAL VENTILATION:AN INTRODUCTION

1

Thursday, April 18, 2013


2/20

LEARNING OBJECTIVES

To know the indication for intubation

and mechanical ventilation. To understand the conceptual

differences between positive and

negative pressure ventilation.



3/20

WHAT IS MECHANICAL VENTILATION

Mechanical ventilation is any means inwhich physical devices or machinesare used to either assist or replacespontaneous respiration.



4/20

NEGATIVE VS POSITIVE PRESSUREVENTILATION

Negative Pressure Ventilation - Pressure lowerthan atmospheric pressure is applied to theextrathoracic space during inspiration.

Positive Pressure Ventilation - Pressure higher than

atmospheric pressure is applied to theintraalveolar space during inspiration.



5/20

NEGATIVE VS POSITIVE PRESSURE VENTILATION

At Rest


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6/20

NEGATIVE PRESSURE VENTILATION


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7/20

NEGATIVE PRESSURE VENTILATION


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8/20

IRON LUNG


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9/20

IRON LUNG


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10/20

IRON LUNG


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11/20

IRON LUNG


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12/20

POSITIVE PRESSURE VENTILATION


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POSITIVE PRESSUREVENTILATION


13/20

POSITIVE PRESSURE VENTILATION


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G S OS SS


14/20

NEGATIVE VS POSITIVE PRESSUREVENTILATION

Major Advantages

No need for sedation

Negative Non-invasive

Pressure

Patient able to eat and talk

Probably lower risk of aspiration

Able to provide higher levels of FiO2

Positive More effective for providing large driving gradients

Pressure Increased ability to individualize treatmentCan provide full ventilatory support for unconscious patients



15/20

INDICATIONS FOR MECHANICALVENTILATION

Need for high levels of inspired oxygen (Hypoxicrespiratory failure)

Need for assisted ventilation ( hypercapnicrespiratory failure or surgical procedures)

Protection of airway against aspiration.

Relief of upper airway obstruction.



16/20


Clinical Scenario 1


17/20

Main Problem Associated Problem Associated Problem

Clinical Scenario 1A 22 year old male found collapsed in the street, pinpoint pupils, respiratory rateof 5 and a PH 7.12 , PCO2 of 70 mmHg, PO2 60mmHg.


SolutionThis man has ventilatory failure, as you can see from his high CO2. He is also somewhat hypoxemic, which is not surprising, as CO2 will displace O2 from thealveolus when it builds up (we know this from the alveolar gas equation: PAO2 = PiO2 PaCO2/R).

The combination of meiosis and bradypnea immediately suggests narcosis, which can be reversed, at least temporarily, with naloxone.

The mechanism of his respiratory failure is thus loss of respiratory drive due to opioids reducing the sensitivity of the respiratory center to carbon dioxide

Clinical Scenario 2


18/20

Clinical Scenario 2A 47 year old male with a two week history of upper respiratory tract infectionis admitted to ER with a history of bilateral lower limb weakness and shortnessof breath. Poor respiratory effort and his pCO2 is 70mmHg and pO2 60mmHg.

Main Problem X X


SolutionThis patient has ventilatory failure, as evidenced by his inability to clear carbon dioxide. His diagnosis turns out to be Guillain-Barre syndrome, which ischaracterized by motor, sensory and autonomic neural demyelination and thus neuropathy, which usually eventually reverses. The low FVC is a sign of poorphysiological reserve, and this patient requires controlled mechanical ventilation.

Clinical Scenario 3


19/20

Clinical Scenario 3A 74 year old female is admitted unconscious, GCS 3, Cheyne Stokes breathing pattern,in atrial fibrillation, BP 170/100mmHg, PCO2 70mmHg, PO2 60mmHg.

Main Problem

X

Main Problem


SolutionThis patient is failing to ventilate and failing to protect her airway. A comatose patient with this breathing pattern is a brain stem stroke until otherwise proven.The cause is either a bleed (hypertension) or an embolus (atrial fibrillation). Mechanical ventilation in this circumstance is invariably futile.


20/20

Thank You


Documents

Lecture 1 Mechanical Ventilation an Introduction