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Fall, 2018

FreshAireTM VitalAire's publication for Healthcare Professionals to help you stay up-to-date on a variety of respiratory related topics.

Please email us at freshaire@vitalaire.ca if you have suggestions on topics you would like highlighted in the next FreshAireTM publication.

NIV for COPD, where are we now?

Chronic Obstructive Pulmonary Disease (COPD) remains a common cause of mortality worldwide. Non-Invasive Ventilation (NIV) has proven to be an efficient tool in both the acute hospital and chronic home care setting. Its use in chronic hypercapnic respiratory failure complicating COPD is well established since the mid-1990’s and is now a standard component of the management of these patients. However, it is important to identify a way to predict NIV failure prior to initiating the therapy, to either provide a more intensive treatment with invasive ventilation or to go with a more conservative and palliative approach. Once NIV has been initiated, the timing and the approach of withdrawal need to be considered. NIV is even considered as a gold standard therapy to treat acute decompensated respiratory failure. NIV is also used to wean a patient from invasive ventilation and in situations when the patient is not suitable for invasive ventilation.

The use of NIV in chronic hypercapnic respiratory failure complicating COPD is well established since the mid-1990’s and is now a standard component of the management of these patients. Established criteria for patient selection include persistent acidosis (pH<7.35), hypercapnia (pCO2>6.5kPa) or tachypnoea (respiratory rate >22 breaths per minute) despite the use of bronchodilators and oxygen therapy. However, the failure rate of NIV is still as high as 20-30% so it’s crucial to refine these criteria. NIV failure is associated with higher in-hospital mortality, length of hospital and critical care stay than NIV success. It is important to identify a way to predict NIV success or failure prior to initiating the therapy, to either provide a more intensive treatment with invasive ventilation or to go with a more conservative and palliative approach. Some indicators that may predict NIV failure are younger age, lower PaCO2 and high arterial lactate, evidence of diaphragmatic dysfunction, persistent tachycardia and acidosis after one hour of NIV initiation. Once NIV has been initiated in acute setting, the timing of withdrawal needs to be considered: however there are contradictory studies on the approach in which NIV should be discontinued, either progressively to avoid the relapse of the hypercapnic failure or immediately.

Discrepancy in results of recent studies on the use of NIV at home for COPD patients suffering of chronic hypercapnic respiratory failure might be related to the selection of patients to undergo and get benefits of the NIV treatment. Obesity appears to be a protective factor in this group of patients: those with a BMI>30kg/m2 who have received home NIV seem to have a longer survival compared to patients with a lower BMI. This obesity paradox has been observed in invasive mechanical ventilation as well. NIV is a therapy often considered in palliative care as it relieves breathlessness. It is used in nearly one third of COPD patients stage 4. However, perceptions amongst patients and clinicians about NIV may be negative: NIV can prolong suffering during the dying process since the mask can be uncomfortable, claustrophobic and may impede communication with friends and relatives. So it is important to document and communicate with the patients and their caregivers on the intended goals of the NIV therapy, its rationale, the expected response, the treatment escalation and/or the withdrawal of therapy, at its initial stage. NIV treatment for COPD patients can also be associated with pulmonary rehabilitation: in this case the combination of both allows to deliver a larger improvement on blood gases.

High Flow humidified oxygen via Nasal Cannula (HFNC) is an emerging method of humidified and heated oxygen delivery which allows an accurate and constant FiO2 to be delivered at high flow rates which can additionally create a small positive mean airway pressure. It is well tolerated by patients and there is evidence to support its use in the critical care setting in non-hypercapnic acute hypoxaemic respiratory failure and post-extubation. HFNC also appears to reduce PaCO2 in stable hypercapnic COPD patients. NIV is the accepted standard of care; however, HFNC may be an option to allow breaks from NIV either to enhance its efficacy or for those unable to tolerate it.

NIV is an effective treatment in COPD patients suffering of hypercapnic respiratory failure. Determining accurate criteria to predict the rate of NIV success remains a challenge but recent studies have provided ome insight into possible indicators. The evidence supporting the use of domiciliary NIV in patients who have previously suffered from an acute hypercapnic episode and remain persistently hypercapnic continues to grow. Finally, use of HFNC continues to grow and may have a role in hypercapnic respiratory failure patients who are unable to receive NIV or invasive mechanical ventilation.
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Oxygen-enriched high-flow nasal cannula therapy for hypercapnic COPD patients.

As for non-invasive ventilation (NIV), the use of oxygen enriched high-flow nasal cannula (HFNC) therapy in acute setting is widely accepted while the clinical benefit to use it at home remains unclear. Patients with end stage COPD frequently develop exacerbations resulting in severely impaired quality of life. As such, the Global Initiative for Obstructive Lung Disease (GOLD) guidelines recommend not only the prevention of disease progression but also the improvement of the quality of life of patients. The use of NIV to treat chronic hypercapnia patients becomes standard. However, discomfort with the facial or nasal interface is one of the main reasons for discontinuation of NIV. High-flow nasal cannula therapy (HFNC), or nasal high-flow therapy, is an alternative therapy developed for respiratory support mainly in the acute setting. Is HFNC suitable for a use at home? is an emerging therapy developed for respiratory support in the acute setting. HFNC has a lower level of positive airway pressure than NIV and decreases inspiratory resistance. In the acute setting, the short-term use of HFNC increases tidal volume, decreases respiratory rate and improves hypercapnia compared with LTOT or spontaneous breathing. HFNC also reduces inspiratory effort and improves lung volume and compliance in patients with acute hypoxemic respiratory failure.

A recent study has been conducted in Japan to compare the effects of HFNC combined with long-term oxygen therapy (LTOT) versus long-term oxygen therapy only in 32 patients with stable hypercapnic COPD. Participants were randomized to receive either 6 weeks of HFNC associated with LTOT followed by 6 weeks of LTOT only or 6 weeks of LTOT only followed by HFNC and LTOT. Study participants allocated to HFNC/LTOT were instructed to use HFNC for at least 4 hours per night during sleep at flow rates between 30 and 40 liters per minute in addition to LTOT. HFNC was administered using myAIRVO 2 device (Fisher & Paykel Healthcare), which provides humidification and high-flow medical gas via an Optiflow nasal cannula interface (Fisher & PaykelHealthcare). The nocturnal oxygen flow rate was adapted to maintain the peripheral oxygen saturation (SpO2) above 88%. In case of discomfort, the flow rate could be decreased to a minimum of 20 L/min. The effective time of use of myAIRVO 2 was obtained from the machine record. Health-related quality of life was assessed using the St. Georges’s Respiratory Questionnaire for COPD. To monitor the effects of both therapies, arterial blood gas were analyzed at the beginning and end of each treatment period, SpO2 was measured using pulse oximetry, and pulmonary function tests were performed according to GOLD recommendations. Nocturnal PtCO2 was also recorded. The most common adverse event related to HFNC was nighttime sweating but none of the affected participants discontinued their treatment.

This study is the first randomized crossover trial to compare home use of HFNC/LTOT with LTOT only for hypercapnic COPD patients. The main finding is that the addition of HFNC to conventional LTOT improved the health-related quality of life. The largest benefit was observed in the symptom score. However, the addition of HFNC did not improve pulmonary function, exercise capacity or physical activity, suggesting that HFNC improves the quality of life through mechanisms that may be independent of lungs and exercise capacity. This study also showed that the use of HFNC decreased PaCO2 by approximately 4mm.

This study has some limitations: the patients were not blinded to the treatment and the coexistence of sleep disorders was not screened during the study: the improvement of quality of life might be due in part to changes in sleep quality thanks to the use of HFNC.

Delivery of heated and humidified oxygen at high flow rates through nasal cannulas is an innovative and powerful technique that is currently changing the management of patients with respiratory failure. Its mechanisms of action and potential clinical benefits can definitely help to improve the management of patients with acute respiratory failure.
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Ask an expert: What makes Non-Invasive Ventilation so special?

We wanted to hear the perspective of a VitalAire respiratory therapists on the use of non-invasive ventilation at home. Susan Carlyle, Respiratory Therapist at VitalAire for 35 years and who has been involved in level 3 studies, CPAP and BiPAP therapy for 6 years, has agreed to answer our questions.

● Can you describe in few words what is NIV and the conditions NIV is used at home (vs in acute care)?
Non-Invasive therapy is used at home to support the patients breathing while sleeping at night in order to maintain good O2 levels and keep CO2 levels normal. NIV keeps them feeling well and out of hospital.The patients apply an interface just like they do for CPAP therapy. Actually, the BIPAP unit looks just like a CPAP/APAP machine. The CPAP/APAP will deliver a single pressure whether they are breathing in or out while a BIPAP machine will deliver 2 pressures: a higher one when breathing in and a lower one when breathing out.

● Which conditions do your NIV patients have?
NIV is generally prescribed for patients suffering of the following conditions: neuromuscular pathologies such as ALS, muscular dystrophy, multiple sclerosis; restrictive pathologies such as kyphoscoliosis (curvature of spine) or severe Obstructive Sleep Apnea (OSA) with hypoventilation.

● Is it difficult for patients to adhere to this kind of treatment?
Indeed, it is difficult for the patients as side effects like dry mouth can be quite disturbing. The patients need to be convinced and committed to adhere to their therapy. In some cases, they feel so much better or they realize they can’t breathe without the therapy. In other cases, they’re coping with pain, anxiety, insomnia and compliance is then difficult to achieve. The success of NIV therapy depends on the collaboration that exists between the patient, the respiratory therapist and the physician: the care team shall help them adapt to the treatment.

● Do you think NIV could be more widely used?
As the morbid obesity rates increase causing more OSA patients to move from CPAP to BIPAP or to start directly with BIPAP, the use of NIV should become more prevalent with the time. The use of NIV would benefit from a rising awareness of the different ventilation modes available in a BIPAP machine, as well as the benefits of the therapy when started sooner rather than later for other conditions than OSA.

● Can you tell us success stories of patients using NIV?
A young woman coping with multiple sclerosis, a diaphragm dysfunction and a recent ARDS was prescribed oxygen at 2-3 lpm. She is a wife and mother of 2 teenagers and a 4 year old. Since being discharged from hospital, activities of daily living are extremly difficult. Her global weakness was even present in her voice. She was admitted to a hospital-based intensive rehabilitation program where she was started on BIPAP therapy PC mode. On the first night she was able to sleep 8 hours on the BIPAP. She noticed a difference the next morning, as she felt more rested, and her voice was stronger.

A gentleman with COPD, obesity and hypoventilation, on oxygen 24/7 was started on BIPAP in July 2015. He was very angry and in denial and he couldn’t tolerate the pressure to the point where he returned his BIPAP. In December 2017, he decided to give it another try as he lost his driver’s license and wanted his independence back. We started him on a lower pressure this time and gradually increased it over a month. He is now using his BIPAP 7-8 hours per night and noticing he has more energy: he’s not as breathless as prior to the therapy and he has applied to get his driver’s license back.
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Product update: AirMini, the smallest CPAP in the world

AirMini is the smallest portable CPAP on the market today, weighing less than a pound and fitting in the palm of your hand. AirMini features HumidX™ and HumidX™ Plus, waterless humidification systems. These 2 humidification systems are small heat and moisture exchangers (HME) that are designed to provide comfortable and effective humidification. The therapy modes CPAP, AutoSet™ (with Response option) and AutoSet for Her are available in AirMini. AirMini is conveniently controled with the AirMini application available for both iOS and Android phones.

During expiration, heat and moisture are capture and stored within the HME’s tiny paper ridges. During inspiration, this heat and moisture are released to humidify the air breath in. HumidX is the standard HME system for most climates and sleep environments while HumidX Plus has been optimized for dry and high altitude environments where humidity levels are low. These HME systems allow the CPAP user to be very mobile with this travel CPAP, as no water is necessary to humidify the air delivered by the machine.

The therapy modes CPAP, AutoSet™ (with Response option) and AutoSet for Her are available in AirMini. Unlike the AirSense™ 10 series, where different devices offer different therapy modes, the AirMini includes all three of these therapy modes.

AirMini is conveniently controled with the AirMini application available for both iOS and Android phones. The app enables to adjust the comfort settings of the unit so the therapy can get as comfortable as possible. The app also provides a 30-day therapy history and a daily therapy score each morning so the patient can stay informed and motivated. ResMed's AirMini now cloud-connects to the AirView remote monitoring platform. The connectivity between AirMini and AirView enables both clinicians and clients to see clients' nightly data, verify adherence, and spot therapy issues.
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TO GO FURTHER

NIV :

Life behind the mask: the patient experience of NIV

https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(14)70267-X/abstract?code=lancet-site

Non-invasive ventilation in acute respiratory failure

British Thoracic Society Standards of Care Committee
http://thorax.bmj.com/content/57/3/192

HFNC :

St George's Respiratory Questionnaire for COPD:

http://www.healthstatus.sgul.ac.uk/sgrq

High-flow nasal cannula: recommendations for daily practice in pediatrics

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4273693/ Christophe Milési, Mathilde Boubal, Aurélien Jacquot, Julien Baleine, Sabine Durand, Marti Pons Odena, and Gilles Cambonie

High-flow nasal cannula support therapy: new insights and improving performance

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5359952/ Gonzalo Hernandez, Oriol Roca, Laura Colinas

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