Respiratory failure mechanical ventilation: Difference between revisions
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==Mechanical ventilation== | ==Mechanical ventilation== | ||
Mechanical ventilation aims to correct abnormalities in oxygenation of the blood and tissues, reduce the respiratory effort and prevent dynamic hyperinflation. | Mechanical ventilation aims to correct abnormalities in oxygenation of the blood and tissues, reduce the respiratory effort and prevent dynamic hyperinflation. | ||
===Principles of Mechanical Ventilation=== | |||
*Mechanical ventilation is basically used to: | |||
**Increase PaO2 | |||
**Lower PaCO2 | |||
**Relieve respiratory effort | |||
===Indications=== | ===Indications=== | ||
| Line 44: | Line 50: | ||
*The tube is affixed in place using tape to prevent accidental extubation or further downward movement toward the main bronchus. | *The tube is affixed in place using tape to prevent accidental extubation or further downward movement toward the main bronchus. | ||
===Types of Mechanical Ventilation=== | ===Types of Mechanical Ventilation=== | ||
====Positive-pressure and Negative pressure ventilation==== | |||
*There are two ways in which a pressure gradient may be created to allow air into the lungs: | |||
**Increase the air pressure in the bronchi (positive pressure) | |||
**Decrease pressure in the alveoli (negative pressure) | |||
====Controlled and patient-initiated ventilation==== | |||
*Ventilatory support may be controlled or patient-initiated: | |||
**Controlled ventilation will deliver support independent of the patient's respiratory efforts | |||
**Patient-controlled ventilation allows ventilation to be delivered in sync with the patient's own spontaneous breathing. In this type of ventilation, the patient's breathing is detected through pressure and airflow trigger mechanisms. | |||
====Pressure-targeted and volume-targeted ventilation==== | |||
*With positive pressure ventilation, pressure or volume may be an independent variable: | |||
**In volume-targeted ventilation, the tidal volume is set by the physician or respiratory assistant, the pressure in this case is a dependent variable. | |||
***This means that airway pressure is the result of a set tidal volume and ispiratory volume, along with the patient's lung compliance, resistance and muscular activity. | |||
**In pressure-targeted ventilation, airway pressure is set, and the volume is dependent. | |||
***The tidal volume in this scenario is a result of inspiratory time, along with the patient's lung compliance, resistance and muscular activity. | |||
===Ventilator Modes=== | ===Ventilator Modes=== | ||
===Positive-End Expiratory Pressure=== | ===Positive-End Expiratory Pressure=== | ||
Revision as of 22:23, 9 March 2018
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Overview
Mechanical ventilation
Mechanical ventilation aims to correct abnormalities in oxygenation of the blood and tissues, reduce the respiratory effort and prevent dynamic hyperinflation.
Principles of Mechanical Ventilation
- Mechanical ventilation is basically used to:
- Increase PaO2
- Lower PaCO2
- Relieve respiratory effort
Indications
- Life threatening respiratory failure:[1][2][3]
- Severe respiratory failure with failure of non-invasive ventilation (NIV) in addition to rapid, shallow breathing, cardiopulmonary arrest, and severe hemodynamic compromise.
- Failure of noninvasive ventilation:
- Indications of failed NIV include:
- A lack of improvement in arterial carbon dioxide tension (PaCO2) and pH within 1.5 - 2 hours
- Encephalopathy
- Agitation
- Unclearable secretions
- Intolerable mask interface
- Decreased oxygen saturation
- Hemodynamic instability
- Indications of failed NIV include:
- Arterial blood gas abnormalities
- Incorrectable hypoxemia despite oxygen supplementation
- Severe respiratory acidosis unresponsive to therapy and/or NIV
Endotracheal intubation
- Endotracheal intubation acts as the connection between the ventilator and the patient.
- Intubation can be performed endotracheally or through a tracheostomy.
- The tube must be placed correctly, and this is confirmed through:
- Chest x-ray
- Chest auscultation
- Carbon dioxide detector
- Proper cuff pressure must be maintained and not exceed 25mmHg
- The airways should be suctioned to ensure patency of the airway:
- Suctioning may occur through an open or closed circuit suction catheter.
- Routine suctioning is not recommended as this may lead to complications such as:
- Desaturation
- Arrhythmias
- Bronchospasm
- Cough
- Entry of secretions into the lower respiratory tract
- The endotracheal tube insertion depth varies by gender and is measured from the lower incisors:
- In males: 23cm
- In females: 21cm
- The tube is affixed in place using tape to prevent accidental extubation or further downward movement toward the main bronchus.
Types of Mechanical Ventilation
Positive-pressure and Negative pressure ventilation
- There are two ways in which a pressure gradient may be created to allow air into the lungs:
- Increase the air pressure in the bronchi (positive pressure)
- Decrease pressure in the alveoli (negative pressure)
Controlled and patient-initiated ventilation
- Ventilatory support may be controlled or patient-initiated:
- Controlled ventilation will deliver support independent of the patient's respiratory efforts
- Patient-controlled ventilation allows ventilation to be delivered in sync with the patient's own spontaneous breathing. In this type of ventilation, the patient's breathing is detected through pressure and airflow trigger mechanisms.
Pressure-targeted and volume-targeted ventilation
- With positive pressure ventilation, pressure or volume may be an independent variable:
- In volume-targeted ventilation, the tidal volume is set by the physician or respiratory assistant, the pressure in this case is a dependent variable.
- This means that airway pressure is the result of a set tidal volume and ispiratory volume, along with the patient's lung compliance, resistance and muscular activity.
- In pressure-targeted ventilation, airway pressure is set, and the volume is dependent.
- The tidal volume in this scenario is a result of inspiratory time, along with the patient's lung compliance, resistance and muscular activity.
- In volume-targeted ventilation, the tidal volume is set by the physician or respiratory assistant, the pressure in this case is a dependent variable.
Ventilator Modes
Positive-End Expiratory Pressure
Inspiratory Flow
Ventilator Induced Lung Injury
References
- ↑ Davidson AC, Banham S, Elliott M, Kennedy D, Gelder C, Glossop A, Church AC, Creagh-Brown B, Dodd JW, Felton T, Foëx B, Mansfield L, McDonnell L, Parker R, Patterson CM, Sovani M, Thomas L (April 2016). "BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults". Thorax. 71 Suppl 2: ii1–35. doi:10.1136/thoraxjnl-2015-208209. PMID 26976648.
- ↑ Confalonieri M, Garuti G, Cattaruzza MS, Osborn JF, Antonelli M, Conti G, Kodric M, Resta O, Marchese S, Gregoretti C, Rossi A (February 2005). "A chart of failure risk for noninvasive ventilation in patients with COPD exacerbation". Eur. Respir. J. 25 (2): 348–55. doi:10.1183/09031936.05.00085304. PMID 15684302.
- ↑ Phua J, Kong K, Lee KH, Shen L, Lim TK (April 2005). "Noninvasive ventilation in hypercapnic acute respiratory failure due to chronic obstructive pulmonary disease vs. other conditions: effectiveness and predictors of failure". Intensive Care Med. 31 (4): 533–9. doi:10.1007/s00134-005-2582-8. PMID 15742175.