All About Home NIV

Respiratory Mechanics

Spontaneous Breathing

Upper airways Nose functions Warm inspired gas Filtre humidification

The lungs are surrounded by ribs and the pleural sac The lungs are surrounded by ribs and the pleural sac. When the ribs lift up and the chest expands , the lungs expand with them. The nose warms and humidifies the air passing into the lungs. Nasal air helps filter the air Air then passes down the wind pipe or trachea. Moving down, the trachea divides into two pipes called the bronchi, on for each lung. All along the windpipes there are very fine hairs called cilia. The cilia help prevent dust and other particles from passing into the lungs and have a wafting action to expel the particles. A cough will also be triggered to remove the particles. The bronchi again divide like branches of a tree until they reach the alveoli which are tiny air sacs. Oxygen passes from alveoli into the blood stream wilst, at the same time, carbon dioxide passes from the blood into the alveoli and is carried away when you breathe out. The diaphram is the most important muscle in breathing. It is a large dome shaped muscle that divides the lung area from the abdominal cavity . When diaphragm contracts the lungs expand and air is drawn in. Each air bag is covered by capillaries

What is spontaneous ventilation? Purpose of ventilation Supply fresh gas to the lungs, to be exchanged at the alveolar-capillary level through blood circulation Provide cells with adequate 02 (Oxygenation) get rid of CO2 (Alveolar ventilation) Maintain normal acid base balance

Arterial Blood Gases Normal values ABGs: Arterial Blood Gases Pa02 and PaC02 Oxygenation assessment Pa02 80-100 mmHg Sa02: 92% to 100% Ventilation assessment PaC02: 35-45 mmHg Acid base status pH:7,35-7,45

Some Definitions Tidal Volume (Vt) Quantity of air in the lungs in 1 inspiration Minute Ventilation Quantity of air in the lungs in 1 min (= Vt x respiratory rate) Hypoxemia state in which Pa02<60 mmHg (in the blood) Sa02<92% (Oxygen saturation) Hypoxia state in which there is inadequate 02 at the tissue level

Some Definitions Hypercapnia when PaC02 >45mmHg Hypocapnia Acidosis: pH<7,35 Alkalosis: pH>7,45 Acidosis happens when there is a increase of the PaCO2, which often happens for COPD patients

Spontaneous breathing At Rest Pressures Equal No Air Flow At rest thepressure in the alveoli is atmospheric. Since there is no pressure gradient between the mooth and alveoli, then there is no movment of air into the lungs.

Spontaneous breathing On Inspiration: Active phenomena Muscles Contract Pressure Changes Air Flows Into Lungs -2 -2 The goal of breathing is to get a certain volume of air into the lungs so that 02 can be exchanged between lungs and blood vaissels and then go to tissues. When a spontaneous inspiration is initiated, muscular effort is exerted by the contraction of the diaphragm and the external intercostal muscles. Inspiration is an active process that requires energy. Contraction of the inspiratory muscles enlarges the thoracic cavity. The lungs expand because they are pulled outward intraalveolar pressure becomes negative and then air at atmospheric pressure flows into the lungs Inspiration continues until intraalveolar pressure rises to equal atmospheric pressure The principle is : air simply moves from an area of high pressure to one of low pressure. Expiration is a passive process that occurs because of the elastic recoil of the lungs Whencontraction of inspiratory muslces ceases the thoracic cage and lungs recoil to their original size

Spontaneous breathing On Expiration: passive phenomena Muscles Contract Pressure Changes Air Flows out Lungs +15 +15 The goal of breathing is to get a certain volume of air into the lungs so that 02 can be exchanged between lungs and blood vaissels and then go to tissues. When a spontaneous inspiration is initiated, muscular effort is exerted by the contraction of the diaphragm and the external intercostal muscles. Inspiration is an active process that requires energy. Contraction of the inspiratory muscles enlarges the thoracic cavity. The lungs expand because they are pulled outward intraalveolar pressure becomes negative and then air at atmospheric pressure flows into the lungs Inspiration continues until intraalveolar pressure rises to equal atmospheric pressure The principle is : air simply moves from an area of high pressure to one of low pressure. Expiration is a passive process that occurs because of the elastic recoil of the lungs Whencontraction of inspiratory muslces ceases the thoracic cage and lungs recoil to their original size

Spontaneous breathing End Expiration: Intrinsic PEEP Resistance creates a residual pressure at the end of expiration +5 +5 The goal of breathing is to get a certain volume of air into the lungs so that 02 can be exchanged between lungs and blood vaissels and then go to tissues. When a spontaneous inspiration is initiated, muscular effort is exerted by the contraction of the diaphragm and the external intercostal muscles. Inspiration is an active process that requires energy. Contraction of the inspiratory muscles enlarges the thoracic cavity. The lungs expand because they are pulled outward intraalveolar pressure becomes negative and then air at atmospheric pressure flows into the lungs Inspiration continues until intraalveolar pressure rises to equal atmospheric pressure The principle is : air simply moves from an area of high pressure to one of low pressure. Expiration is a passive process that occurs because of the elastic recoil of the lungs Whencontraction of inspiratory muslces ceases the thoracic cage and lungs recoil to their original size Extra work is needed to generate the following inspiration

Spontaneous breathing Opposing Forces to Ventilation Elastic recoil Resistance of the lungs to airflow Work of Breathing Inspiration is an active process and even if we are healthy, we need to spend energy to be able to breath. There are natural forces that opose to ventilation (movement of air into the lungs) Elastic recoil of the lungs Resistance to air flow (at the level of airways) The energy we need to spend to overcome these 2 forces is called work of breathing.

Opposing Forces to Ventilation Tendency of the Lungs to Resist Inflation Pressure / Volume = Elastance Resistance to Air Movement in the Airways Pressure / Flow rate = Airways Resistance

Breathing with Lung Disease Decreased Elastance Increased Resistance Stronger Muscle Contractions Required Larger Patient Effort Excessive Work of Breathing Respiratory Failure When a patient is presenting with a lung disease , the opposing forces to ventilation are increased and depending on the type of disease it could be increase in resistance (like COPD), increase in compliance (Pneumonia) The work required to overcome the opposing forces to ventilation would be highter. Therefore the work of breathing would be higher. The patient will not be able to maintain this high workload for a long time and this condition would lead to respiratory failure

Breathing with Lung Disease Flow and/or Volume Normal Disease Patient Effort

Consequences of Respiratory Failure Excessive Work of Breathing Respiratory Muscle Dysfunction Inadequate Alveolar Ventilation Severe Hypoxia The candidates for mechanical ventilation are those patients whose lungs can no longer provide adequate exchange of gases this inadequacy is reflected in the blood gases

Goals of Ventilatory Support Improve Alveolar Minute Ventilation Decrease the Work of Breathing Correct Gas Exchange Abnormalities I ’s important to understadn that ventilatory support does not cure he patient. It gives time while treatment is efficient.

Types of Ventilatory Support Invasive endotracheal tube tracheostomy Noninvasive mask 2 ways to give ventilatory support we will beb talking about Noninvasive ventilation and we’ll see later on what could be the benefit of such a ventilation

Home NIV Objectives Correct hypoventilation and associated syndromes (like OSA): Despite the leaks Ensuring a good comfort Preserving a good quality of sleep Provide a comfortable ventilation to ensure a good patient compliance May prefer comfortable parameters (IPAP, EPAP, RR) with a higher CO2 level Adapt the patient to his therapy takes time: if it has already failed once then it is even more difficult the second time!

Restrictive pathologies Obstructive pathologies Expected Results Restrictive pathologies Obstructive pathologies Short Term Symptoms relief Reduce desaturations Reduce desaturations and increase ventilation (overcome oxygen side effect) Long Term Reduce Pa C02 Improve survival Reduce decompensation episodes Reduce Pa CO2 Improve quality of life Reduce decompensations episodes risks (or at least severity)

Which pathologies would benefits from Home NIV?

What is CRF? Chronic respiratory failure (CRF) may result from different pathologies, which make the body inept to bring oxygen and/or wash out its CO2. As a result there is a decrease of the PaO2 (hypoxemia) and/or an increase of the Pa CO2 (hypercapnia) noticed during blood gases analysis In comparison with OSA patients: OSA patients have healthy lungs. They « just » have upper airways obstructions. Therefore they need positive pressure to open the upper airways. CRF patients need « ventilation », CPAP does not provide ventilation as it does not provide pressure support

Chronic Respiratory Failure Patients Management « The management strategy is based on an individualized assessment of disease severity and response to various therapies. » Source: Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease GOLD scientific committee - NHLBI/WHO workshop summary - AJRCCM 2001 « The approach to the specific diseases in this category may not be entirely uniform » consensus conference, Chest 1999 « The current study also concludes that long term home NPPV should be tailored to the individual patient » Source: « Would Euclid Approve of How We Select Mechanical Ventilators » Carlon, Combs (US) - Chest 2002 Therapy depends upon the patient’s pathology type and severity

COPD and Ventilation

COPD Patient Some definitions Chronic Obstructive Pulmonary Disease is the name given to the progressive narrowing of the airways This narrowing may result from an obstruction of the airways in patients with Chronic Bronchitis (scarring of the airways and sputum secretion) or emphysema Emphysema Emphysema is brought about by cigarette smoking which results in chemical changes that destroy lung tissue: Loss of lung tissue: reduction of elasticity Airways tend to close Emphysema results principally from chronic infection caused by inhaling smoke

Phlegm damages the tissue COPD Swollen airways On COPD, the air sacs (alveoli) can collapse and the tissue besomes destroyed. The body has to work harder to breathe out and the effort can make more tubes collapse. Phlegm becomes trapped and is prone to infection.These effects are common in emphysema Alveoli collapse Phlegm damages the tissue Chronic Bronchitis Narrowed airways Emphysema

Pink puffer Emphysema dominant COPD COPD patients are very heterogeneous. Pink puffer have intrinsic PEEP Blue blotters are very often overlap syndrome with hypoxemia Blue bloater Bronchitis dominant Pink puffer Emphysema dominant

COPD Patient Therapies <70% FEV1/FVC <30% Mild stage Mild airflow limitation Moderate stage Worsening airflow limitation Severe stage Severe airflow limitation Drugs & Physiotherapy Long Term Oxygen Therapy Noninvasive Ventilation « As the disease progresses, hypoxemia occurs and hypercapnia is seen in advanced disease »  Source: Global Strategy for the Diagnosis, Management, and Preventation of Chronic Obstructive Pulmonary Disease GOLD scientific committee - NHLBI/WHO workshop summary - AJRCCM 2001

COPD Patient Oxygen Therapy LTOT (12-17hrs/day) has been shown to Increase survival Decrease hospitalization rate Adverse effects: Hypoventilation and CO2 retention Increased PaCO2 at night may contribute to arousals Sudden High PaCO2 deteriorate the gas balance and may lead to acidosis (exacerbation risks) LTOT to preserve vital organ function by ensuring an adequate delivery of oxygen If PaO2<70mmHg often ther is an Hypercapnia associated. « Whether LTOT improves sleep quality is unknown » Diagnosing patients with COPD and OSA – sleep review Normal gases: PaCO2=35-45mmHg PaO2=80-100mmHg SaO2>90% PH=7.35-7.45 Hypoxemia state in which Pa02<60 mmHg (in the blood) Sa02<92% (Oxygen saturation)

COPD Patients Home NIV Therapy Conflicting results of studies COPD population likely to benefit from NIPPV : Substantial daytime CO2 retention Severe airway obstruction Nocturnal oxygen desaturation Benefits: Reduce nocturnal hypoventilation: allows respiratory centre to reset, improves daytime hypercapnia. Improve sleep quality by reduced episodes of hypoventilation and desaturations Resting chronically fatigued respiratory muscles, allowing recovery of inspiratory muscle function Decrease Decompensation episodes risks/severity Benefits: improve patient quality of life Criteria usually followed in the daily practice to select proper candidates: Repeated decompensation episodes in the last 3 months Acceptation of the therapy (compliance: 8hrs ventilation at night When you speak to physicians who are not convinced on COPD ventilation (or if they still daoubt on the benefit of NIV) you can refer ro the conference consensus. Assumptions for NIV & COPD: Prevent from exacerbation or reduce severity of exacerbations, reduce re hospitalization rate But the COPD who benefit from NIV should be carefully selected: those who are hypoxemic (acidosis risks: exacerbations) and those who still desaturate at night with LTOT (prevalence unknown) In UK, in most Nordic countries, in Greece, COPD patients are only ventilated at hospital in the case of ACRF and very rarely at home: there is here a huge potential to increase the market size by increasing the number of ventilated COPD patients Source: Consensus conference : « Clinical indications for noninvasive positive pressure ventilation in chronic respiratory failure due to restrictive lung disease, COPD and Nocturnal hypoventilation » Chest 1999

COPD Patient & NonInvasive Ventilation Gas exchange criteria Daytime PaCO2 > 55 mmHg or Nocturnal oxygen desaturation : SaO2 < 88% for > 5 min sustained while receiving oxygen therapy (<2l) PaCO2 of 50-54 mmHg and hospitalization related to recurrent episodes of hypercapnic respiratory failure (> 2 episodes in 1 year) Source: Consensus conference - Chest 1999 In the consensus conference they give indications on the way to select COPD candidates for Home NIV Improvment of ABG at night lead to daytime PaCO2 improvement A Simonds decided to ventilated COPD patients to reduce her cost of hospitalizatio since decompensation of COPD patients was taking a big part of the budget. Criteria usually followed in the daily practice: Repeated decompensation episodes in the last 3 months High CO2 level Acceptation of the therapy (compliance: 8hrs ventilation at night)

Evidence Statements from NICE Addition of NIV to LTOT improved daytime PaCO2 during oxygen breathing Resting dyspnoea improved in NIV+LTOT group, and was significantly better at month 24 After 2 years QOL was significantly improved Overall hospital admissions decreased by 45% in the NIV+LTOT group compared with increase of 27% in LTOT (follow back period of 12 months) http://thorax.bmjjournals.com/content/vol59/suppl_1/ The evidence statements in the NICE Guidelines (published in Thorax 2004) are primarily drawn from the study published by Clini et al in European respiratory Journal in 2002. This was an italian multicentre trial involving 122 patients randomised to LTOT+ NIV or LTOT alone. Addition of NIV in these stable COPD patients reduced daytime CO2 retention and improved quality of life scores. Although hospital admissions in the follow up period were not significantly different, but overall hospital admissions decreased by 45% in the NIV+LTOT group compared with increase of 27% in LTOT only group when the followback period of 12 months before the study was taken into account. Survival was similar. There were significant benefits from use of nocturnal NIV, although further work is necessary to evaluate the effects of NIV on reducing severity and frequency of acute exacerbations

NICE Recommendation Adequately treated patients with chronic hypercapnic respiratory failure who have required assisted ventilation (whether invasive or non-invasive) during an exacerbation or who are hypercapnic or acidotic on LTOT should be referred to a specialist centre for consideration of long-term NIV. There are additional inconsistent data from small no of studies on small numbers of patients that NIV produces improvements in blood gases, dyspnoea, QOL and exacerbation rates Patients with chronic hypercapnic respiratory failure who have been ventilated during an exacerbation or who are intolerant of LTOT may get improvements in blood gases, dyspnoea, QOL and exacerbation rates when treated with NIV. Chronic Obstructive Pulmonary Disease: National clinical guideline on management of chronic obstructive pulmonary disease in adults in primary and secondary care Thorax 2004;59(suppl 1) 1-232

Restrictive Patients and Ventilation

Restrictive Patients Different Diseases Obese Hypoventilation Chest wall deformities Kyphoscoliosis Sequel of tuberculosis Non progressive or slowly progressive neuromuscular disorders Central hypoventilation Spinal cord injury, spinal muscular dystrophy Myopathies Sequel of Poliomyelitis Progressive neuromuscular disorders Amyotrophic Lateral Sclerosis (ALS) Duchenne muscular dystrophy Chest wall deformities  Kyphoscoliosis: posterior curvature of the spine: -         Breath sounds -         Dyspnea -         Increased PaCO2 -         Atelectasis -         Recurrent pulmonary infections.  Sequel of tuberculosis: Tuberculosis is an inflammatory pathology: bacterial infection that leads to lesions. The lung compliance can be reduced. Slow progressive and non-progressive disorders Central Hypoventilation: the metabolic control of the ventilation is abnormal and may lead to apnoeic episodes. Hypoventilation may have different causes: brainstem lesions, obesity, congenital..etc and it is characterized by hypercapnic respiratory failures. There is a huge variation of the level of ventilation dependency. Spinal cord injuries: Deficit in sensation and motor functions due to accident, brainstem ... The degree which individual patients are affected depends on the level and extent of the spinal cord lesion. Post polio syndrome: (PPS) is a condition that can strike polio survivors anywhere from 10 to 40 years after recovery from the initial condition. PPS is characterized by the further weakening of muscles that were previously injured. The severity of PPS depends on the severity of the first bout, however, the condition is not life threatening. Poliomyelitis is caused by a virus that leads to a progressive paralysis. Progressive neuromuscular diseases ALS: It attacks nerve cells in the brain and spinal cord. As the nerve cells die, the brain’s ability to initiate and control muscle movement is lost. In the later stages of the disease, patients become paralyzed and ultimately die. ALS patients’ ability to think, their sense of sight, taste, touch, hearing, and smell, as well as muscles of the eyes and bladder are not affected by the disease. Muscular dystrophy: it is a group of genetic disorders characterized by progressive muscle weakness and degeneration in different muscles of the body. This group of diseases has three common features: They are hereditary They are progressive Each has a pattern of muscle weakness different from the other forms. Duchenne and Becker muscular dystrophy are the only types of the disease that can be inherited

Restrictive Patients Pathology Progression <50% FVC <20% Mild stage Moderate stage Severe stage Physiotherapy Noninvasive Ventilation Invasive ventilation Early Stage: preventive ventilation Moderate and severe stages: needed ventilation The dependence to the ventilation increases FVC: Forced Vital Capacity Home ventilation can be initiate quite early on restrictive patients to adapt him progessivly and avoid exacerbation episodes. From the book “assistance ventilatoire à domicile”: Needed ventilation if: PaCO2 > 45 mmHg Or Nocturnal desaturation : SaO2 < 88% for > 5 min Source: book “Assistance Ventilatoire à Domicile” D Robert, B.J. Make, P Léger, A. L. Goldberg, J. Paulus, T. Willig – 1994 Source: Consensus Conference - Chest 1999

Restrictive Patients “More recent reviews have cited the advantages of pressure targeted devices for comfort and their ability to compensate for leaks. Volume targeted equipment may be favorable for many patients simply because triggering mechanism are more adjustable and pressure targeted systems are not able to guarantee a minimum minute ventilation.” Source: Consensus Conference - Chest 1999 10 years ago: Invasive ventilation/volume at the late stage of the disease Today: Start at the early stage in pressure support Use security functions while patient becomes dependant Ends up with invasive ventilation (< 5% of patients) With restrictive patients physicians try to find the good combination between comfort and safety, but most of the time they choose to give advantage to the Safety The problem of restrictive patients is to deliver the right tidal volume that is why first volume ventilation was used

Restrictive Patients When shall we start NIV? Gas exchange criteria PaCO2 > 45mmHg Or SaO2<88% during 5min Or VC<50% of predicted Source: Consensus conference - Chest 1999