Biphasic Cuirass Ventilation
Encyclopedia
Biphasic cuirass ventilation (BCV) is a method of ventilation
which requires the patient to wear an upper body shell or cuirass
, so named after the body armor worn by medieval soldiers. The ventilation is biphasic because the cuirass is attached to a pump which actively controls both the inspiratory
and expiratory
phases of the respiratory cycle. This method has also been described as 'Negative Pressure Ventilation' (NPV), 'External Chest Wall Oscillation' (ECWO), 'External Chest Wall Compression' (ECWC) and 'External High Frequency Oscillation' (EHFO). BCV may be considered a refinement of the iron lung
ventilator. Biphasic cuirass ventilation was developed by the late Dr Zamir Hayek, a pioneer in the field of assisted ventilation. Some of Dr Hayek's previous inventions include the Hayek Oscillator, an early form of the technology.
As the ventilation provided by the cuirass is biphasic, it is possible to achieve both large breaths (tidal volume
s) and a high respiratory rate
(from 6 to 1200 breaths per minute). The biphasic function allows control over the I:E ratio, which is the ratio between the time allowed for inspiration (pumping air out of the cuirass and creating a negative pressure around the chest) and expiration (pumping air into the cuirass and creating an increase in pressure around the chest.) Most other types of ventilation depend on the passive recoil of the patient's chest, which limits the respiratory rate.
. Unlike intermittent positive pressure ventilation (IPPV), BCV is active in both the inspiratory and expiratory phases (biphasic). This allows greater control over the tidal volume
s and respiratory rate. BCV may also help to maintain and redevelop the respiratory muscles which may weaken with respiratory failure and mechanical ventilation, this allows patients to be weaned from a ventilator. BCV also does not impair cardiac function, as IPPV does. BCV is often used as an aid in patients with poor cardiac output.
Unlike conventional negative pressure ventilation, biphasic cuirass ventilation is able to quickly reduce any harmful buildup of CO2 using its active expiratory phase. Many published papers and case studies now show how effective BCV is at reducing CO2 buildup. It has also now been shown that the most effective ventilation frequency to reduce CO2 when using BCV is 60 cycles per minute. The oscillations caused by BCV assist in the removal of secretions which are a symptom of many respiratory diseases. Lastly, because BCV does not require the patient to be intubated or to have a tracheostomy, patients can have BCV at home.
BCV has also been successfully used in a case of failed fiberoptic intubation, in microlaryngeal surgery, and after paediatric cardiac operations.
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
which requires the patient to wear an upper body shell or cuirass
Cuirass
A cuirass is a piece of armour, formed of a single or multiple pieces of metal or other rigid material, which covers the front of the torso...
, so named after the body armor worn by medieval soldiers. The ventilation is biphasic because the cuirass is attached to a pump which actively controls both the inspiratory
Inhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....
and expiratory
Exhalation
Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....
phases of the respiratory cycle. This method has also been described as 'Negative Pressure Ventilation' (NPV), 'External Chest Wall Oscillation' (ECWO), 'External Chest Wall Compression' (ECWC) and 'External High Frequency Oscillation' (EHFO). BCV may be considered a refinement of the iron lung
Iron lung
A negative pressure ventilator is a form of medical ventilator that enables a person to breathe when normal muscle control has been lost or the work of breathing exceeds the person's ability....
ventilator. Biphasic cuirass ventilation was developed by the late Dr Zamir Hayek, a pioneer in the field of assisted ventilation. Some of Dr Hayek's previous inventions include the Hayek Oscillator, an early form of the technology.
As the ventilation provided by the cuirass is biphasic, it is possible to achieve both large breaths (tidal volume
Tidal volume
Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied.Typical values are around 500ml or 7ml/kg bodyweight.-Mechanical Ventilation:...
s) and a high respiratory rate
Respiratory rate
Respiratory rate is also known by respiration rate, pulmonary ventilation rate, ventilation rate, or breathing frequency is the number of breaths taken within a set amount of time, typically 60 seconds....
(from 6 to 1200 breaths per minute). The biphasic function allows control over the I:E ratio, which is the ratio between the time allowed for inspiration (pumping air out of the cuirass and creating a negative pressure around the chest) and expiration (pumping air into the cuirass and creating an increase in pressure around the chest.) Most other types of ventilation depend on the passive recoil of the patient's chest, which limits the respiratory rate.
Uses
BCV has been successfully used on patients with:- Acute respiratory failure
- Chronic obstructive pulmonary diseaseChronic obstructive pulmonary diseaseChronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
(COPD) - Neuromuscular (e.g. SMA, Duchennes, etc.)
- Head and spinal injuries
- Problems with weaning from positive pressure ventilation (PPV)
- Ventilation during anesthesia in ear, nose, and throat (ENT) procedures
- Cystic fibrosisCystic fibrosisCystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...
(CF), and those who require physiotherapy - AIDSAIDSAcquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
related lung disease - AsthmaAsthmaAsthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
- Ventilation post-operation Eg. post-coronary bypass, Fontan, Fallot, post-pneumonectomy
- Ondine's curseOndine's curseOndine's Curse, also called congenital central hypoventilation syndrome or primary alveolar hypoventilation, is a respiratory disorder that is fatal if untreated...
Advantages
BCV is non-invasive and therefore avoids some of the problems associated with invasive ventilation such as infection and barotraumaBarotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...
. Unlike intermittent positive pressure ventilation (IPPV), BCV is active in both the inspiratory and expiratory phases (biphasic). This allows greater control over the tidal volume
Tidal volume
Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied.Typical values are around 500ml or 7ml/kg bodyweight.-Mechanical Ventilation:...
s and respiratory rate. BCV may also help to maintain and redevelop the respiratory muscles which may weaken with respiratory failure and mechanical ventilation, this allows patients to be weaned from a ventilator. BCV also does not impair cardiac function, as IPPV does. BCV is often used as an aid in patients with poor cardiac output.
Unlike conventional negative pressure ventilation, biphasic cuirass ventilation is able to quickly reduce any harmful buildup of CO2 using its active expiratory phase. Many published papers and case studies now show how effective BCV is at reducing CO2 buildup. It has also now been shown that the most effective ventilation frequency to reduce CO2 when using BCV is 60 cycles per minute. The oscillations caused by BCV assist in the removal of secretions which are a symptom of many respiratory diseases. Lastly, because BCV does not require the patient to be intubated or to have a tracheostomy, patients can have BCV at home.
BCV has also been successfully used in a case of failed fiberoptic intubation, in microlaryngeal surgery, and after paediatric cardiac operations.