HOME NON INVASIVE POSITIVE PRESSURE VENTILATION BY AHMAD

HOME NON INVASIVE POSITIVE PRESSURE VENTILATION BY AHMAD YOUNES PROFESSOR OF THORACIC MEDICINE Mansoura Faculty of Medicine

Non-invasive ventilation • Non invasive ventilation refers to techniques that provide alveolar ventilation without an invasive artificial airway in place i. e. endotracheal or tracheostomy tube is not needed. • This can be accomplished by either negative or positive pressure.

Home Ventilation • Non Invasive Ventilaion A) Negative pressure ventilation B) Positive pressure ventilation (Pressure preset ventilation or volume preset ventilation or dual modes). • Invasive Ventilaion (Pressure preset ventilation or volume preset ventilation or dual modes). .

Non-invasive ventilation • In the vast majority of cases therapy will be delivered with positive pressure devices, although a few individuals still use negative pressure devices. • Negative pressure devices present a number of difficulties with regard to home ventilation including bulkiness, fit and comfort , they can induce significant upper airway obstruction , rendering therapy ineffective.

External Negative Pressure Ventilation • ENPV is provided by a variety of devices applied externally to the chest wall and abdomen. • These devices generate intermittent subatmospheric pressure and thus inspiratory airflow. • Exhalation is usually passive, resulting from the inward elastic recoil of the lung and chest wall.

Devices of ENPV • Tank ventilator “iron lung”: the most effective one. • Cuirass. • Jacket ventilator. • Hayek oscillator: the most recent variation of cuirass negative pressure ventilator

Iron-lung

Cuirrass

Non-invasive ventilation • Prior to the introduction of NIV in the mid 1980’s, home ventilation was restricted to negative pressure devices used primarily in patients with poliomyelitis, and tracheostomy ventilation used for patients with severe respiratory muscle weakness or total paralysis. • Both forms of ventilatory support were associated with significant practical difficulties, which meant that home ventilation was restricted to a small number of individuals usually with complex chronic health care needs.

Non Invasive Positive Pressure Ventilation • The simplicity, cost and acceptability of NIV has led to this approach being widely adopted by the respiratory community and accepted by patients to the extent that NIPPV is now considered first line therapy in the management of chronic respiratory failure. • Importantly, it is now recognized clinically that ventilatory support during sleep is all that is required to achieve sustained daytime improvements for most patients.

Non Invasive Positive Pressure Ventilation • European survey of home ventilation identified almost 22, 000 users in 16 countries, 87% of whom used non-invasive ventilation. • NIPPV is acceptable to patients on a long-term basis and can alleviate symptoms related to chronic hypoventilation , improving survival and quality of life.

Non Invasive Positive Pressure Ventilation • Volume preset ventilation delivers a stable tidal volume irrespective of the patient’s pulmonary system mechanics (compliance, resistance and active inspiration). In contrast, pressure preset ventilation delivers a set pressure during inspiration and expiration, and changes in the patient’s pulmonary mechanics directly influence the flow and the delivered tidal volume. • Most studies evaluating these two modes in patients with chronic respiratory failure have shown equivalent effects with respect to maintaining nocturnal gas exchange and improving daytime blood gases.

Non Invasive Positive Pressure Ventilation • Due to lower cost and greater patient comfort , most patients in the majority of centres are now prescribed pressure preset devices, mostly commonly, bilevel machines. • volume ventilators are recommended for patients with the most severe respiratory failure including those with tracheostomy and when continuous or near continuous ventilator support is needed. • A switch from pressure to volume preset ventilation may also be required in patients who are adherent to pressure preset ventilation but who fail to respond to treatment. • No difference in blood gas improvement, lung function or compliance with therapy was seen between the two modes.

Non Invasive Positive Pressure Ventilation • The pressure settings used in bilevel devices include the inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP), with the difference between the two determining the level of pressure support. • Volume preset ventilators are usually set in an assist / control or control mode of support. • Pressure preset devices may be set in an assist (“spontaneous”) mode where each breath is patient triggered; an assist / control (“spontaneous/ timed”) mode where breaths may be patient or machine triggered; and a control (“timed”) mode where all breaths are machine triggered only.

Non Invasive Positive Pressure Ventilation • A recent innovation in this area is that of autotitrating bilevel and trilevel devices. • The algorithms of these machines are designed to automatically titrate pressure support levels, and in some devices EPAP, based on minute ventilation or flow targets. • There is mounting evidence for the use of these devices in managing sleep disordered breathing in patients with central sleep apnoea / Cheyne– Stokes respiration.

Home Non Invasive Positive Pressure Ventilation 1 - Uni-level positive airway pressure. A-CPAP B-Auto-CPAP 2 - Bi-level positive airway pressure. A- Fixed Bi-level positive airway pressure. B- Automatic Bi-level positive airway pressure eg. Average volume assured pressure support (AVAPS) or Volume compensation , Average volume assured pressure support with Automatic expiration (AVAPS-AE) , Intelligent volume assured pressure support (i. VAPS) 3 - Tri-level positive airway pressure (fixed and automatic). 4 - Automatic Bi-level or Tri-level positive airway pressure with servo-ventiation eg. Adaptive Servo Ventilation (ASV), Bi. PAP auto-SV , Anti-cyclic Servo-Ventilation (Ac. SV)

Home Non Invasive Positive Pressure Ventilation • Nocturnal Ventilatory Support ( sleep disordered breathing) Usually Pressure preset ventilators. • Nearly Continuous (>18 hours) Ventilatory Support (Nocturnal Ventilatory support + most daytime ventilatory support ) Usually Volume Preset Ventilators. • Continuous ventilatory support (Ventilator dependent individuals ) Life Support Ventilators ( BACK UP RATE , POWER FAILURE ALARMS , MASK OFF ALARMS , LOW PREASSURE ALARMS )

Goals of Non Invasive Positive Pressure Ventilation • For those with stable or slowly progressive disorders, the purpose of providing ongoing therapy is to increase survival while maintaining or improving the quality of life. • In rapidly progressive disorders, the primary goal is to palliate symptoms. • In a small group of individuals, such as those with cystic fibrosis, home NIPPV may provide a temporizing measure until transplantation is possible. • The non-invasive approach also permits earlier intervention in the course of the disease than is possible with invasive techniques , reduces acute care costs by decreasing hospital length of stay and readmissions , and simplifies the burden of care related to managing chronic respiratory failure in the home.

Patient Selection • Criteria for selecting patients for NIPPV: 1. Alert & cooperative. 2. Hemodynamic stability. 3. No need for endotracheal intubation: to protect airways or to remove excessive secretions. 4. No acute facial trauma. 5. Properly fitted mask. 6. No multi-organ dysfunction.

Exclusion criteria: 1. Respiratory arrest. 2. Cardiovascular instability (hypo tension, arrhythmias, myocardial infarction). 3. Somnolence impaired mental status, uncooperative patient. 4. High aspiration risk; Viscous or copious secretions. 5. Recent facial or gastro-esophageal surgery. 6. Crainio-facial trauma, fixed naso-pharyngeal abnormalities. 7. Burns. 8. Extreme obesity (>200% of ideal body wt).

Advantages of NIPPV • Better tolerance. • No need for sedation. • Patient can talk, eat, … Drawbacks of NIPPV • Claustrophobia. • Air leaks. • Facial skin necrosis • Gastric distension • Eye irritation.

Uni-level positive airway pressure Top: Normal pressure curve (pressure measured at the mouth level) breathing at ambient ("0") pressure; airway pressure is @ -3 cm H 2 O at peak of inspiration (I) and @ +3 cm H 2 O at peak of expiration (E). Bottom: Pressure curve when CPAP = 5 cm H 2 O; the baseline pressure against which the patient breathes is raised 5 cm H 2 O above ambient. I = peak of inspiration, E = peak of expiration.

CPAP from different manufacturers

This schematic tracing of delivered pressure over an entire night illustrates that the patient slept at a lower pressure for most of the night than a single fixed pressure that would be effective in all body positions. The APAP device increased pressure when the patient was supine.

Automatic CPAP

Fixed Bi-level Positive Airway Pressure curve when Bi. PAP = 10/5 cm H 2 O; The pressure is higher on inspiration than on expiration, but both pressures are above ambient. In this example IPAP is set as 10 cm H 2 O and EPAP is set as 5 cm H 2 O.

Bilevel machines from different manufactures

Bilevel Positive Airway Pressure -Average Volume Assured Pressure Support (Bi. PAP -AVAPS) , Volume Copensation

Bilevel Positive Airway Pressure -Average Volume Assured Pressure Support (Bi. PAP AVAPS) , Volume Copensation

Average Volume Assured Pressure Support – Automatic Expiration (AVAPS –AE )

AVAPS –AE Bi. PAP A 40 Ventilator , Prisma ST 30

Variable Positive Airway Pressure - Intelligent Volume Assured Pressure Support (VPAP - i. VAPS )

Intelligent back up rate (i. BR) stays out of the way at 2/3 spontaneous rate whenever the patient spontaneously triggers above 2/3 of the target. once the patient rate reach minimum back up rate (2/3 of the target ) i. BR increase towards patient spontaneous rate to maintain alveolar ventilation. Once spontaneous trigerring returns, i. BR drops back to 2/3 of the target / spontaneous rate.

Stellar 150 and VPAP™ ST with i. VAPS

Tri-level Positive Airway pressure The difference between IPAP and EPAP defines the tidal volume. The EEPAP varies automatically due to the level of the upper airway obstruction

Somnovent S/T , CR and Prisma S/T, Anti-cyclic Servo-Ventilation

Automatic Bi-level or Tri-level positive airway pressure Adaptive Servo Ventilation (ASV), Anti-cyclic Servo. Ventilation(Ac. SV) ASV is Bi. PAP with a twist. The IPAP and EPAP can vary, depending on the patient's needs. In some ASV-type machines the EPAP is fixed and only the IPAP changes; in others both can change. Basically, in ASV one or both pressures is continously adjusted, so that the ventilation delivered to the patient 'adapts' to the situation.

Prisma Ac. SV Bi. PAP auto SV VPAP adapt SV Medicraft ASV

Pathologic defaults

Stellar 150 pathologic default settings

Nearly Continuous (>18 hours) Ventilatory Support (Nocturnal Ventilatory support + most daytime ventilatory support ) or Continuous Ventilatory Support eg. Bi. PAP A 40 Ventilator VENTImotion 2 and VENTIlogic LS

Carrying Case. The bag is designed to attach the ventilator to a wheelchair