The complexity of patients living longer with multiple comorbidities means that more patients are requiring long-term non-invasive positive pressure ventilation (NPPV), both in hospital and at home. NPPV reverses or safely maintains the arterial acid-base balance associated with hypercapnic or type 2 respiratory failure. In the home environment, the main reasons for NPPV therapy are to preserve quality of life and maintain life expectancy, depending on the condition that is being treated (Simonds, 2012; Gale et al, 2015). For some patients, this therapy is used to reduce symptoms associated with more severe disease in later stages of life, such as breathlessness, sleep disturbance and daytime sleepiness. Although most patients commenced on NPPV will have been reviewed and assessed by a specialist team, having an understanding of the therapy and the challenges it presents can significantly help support patient compliance and has the potential to reduce the problems that patients experience. New data is emerging around the use of this therapy, especially for patients with chronic obstructive pulmonary disease (COPD), who have shown improved admission-free survival rates with NPPV (Criner et al, 2018). Thus, the potential of the application of NPPV in the home environment is increasing. With this, nurses and other healthcare practitioners may be asked to support patients receiving NPPV in the home environment, including the application of masks and support with equipment. Nurses having specialist knowledge and understanding of NPPV within the home environment will promote patient compliance and reduce hospital admissions and complications associated with NPPV therapy.
NPPV should not be confused with home continuous positive airway pressure (CPAP). To clarify, CPAP therapy is the application of a single pressure through the airway rather than bi-level. Some patients receive home CPAP for obstructive sleep apnoea (OSA) and obstructive sleep apnoea syndrome, and these machines and masks are similar to those used in bi-level therapies, so troubleshooting is similar. However, most of these patients will not have type 2 respiratory failure.
Type 2 respiratory failure or hypercapnic respiratory failure occurs when ventilation is ineffective (Smyth, 2005). This is when carbon dioxide is increasingly accumulated within the body (Nair and Peate, 2013) and can happen acutely or as a chronic condition. The causes of chronic type 2 respiratory failure are poor ventilation, failure of the respiratory muscles or ineffective transfer of oxygen and carbon dioxide in and out of the alveoli (Smyth, 2005). Accumulation of carbon dioxide in the body causes a change in the body's acid-base balance (Nair and Peate, 2013). Consequently, the pH of arterial blood drops to less than 7.35, making it increasingly acidic. If this continues, the body will compensate by producing additional bicarbonate (Shneerson, 2012). The production of bicarbonate reduces the hyperacidity caused by the carbon dioxide, but for some patients, this compensation is not effective. This can cause patients to symptomatically feel breathless (Shneerson, 2012) and generally unwell and have sleep disturbance, daytime sleepiness (somnolence) (Eng, 2006), mental lethargy and early-morning headaches. It is this long-term raised carbon dioxide and symptom burden that can be managed by the use of NPPV in the home environment.
This article discusses the care of patients with NPPV in the home environment. It looks at why patients require this therapy and describes the support and care that patients in the home environment may require to help maintain their compliance and concordance with NPPV.
Non-invasive positive pressure ventilation
NPPV has multiple functions to support breathing (Table 1). The ventilator provides positive pressure at two different levels that work in time with breathing: the inspiratory positive air pressure (IPAP), which is high, and expiratory positive air pressure (EPAP), which is low (Preston and Kelly, 2017). The use of the two different levels assists lung inflation on inspiration and supports expiration within the airway, thereby reducing any possible airway collapse. The difference between the two pressures is known as ‘pressure support’ (Preston and Kelly, 2017). The IPAP and pressure support inflate the alveoli, increasing the breath size (tidal volume) and allowing the patient to more efficiently exhale the retained carbon dioxide (Preston and Kelly, 2017). Using a higher EPAP helps support more alveoli or a collapsed larger airway and thus improving oxygenation; there should always be a difference in the two levels (Preston and Kelly, 2017). Pressure support is an important element of NPPV therapy, as this is when the body releases carbon dioxide. The IPAP and EPAP are set by the specialised healthcare team that reviews the patient's condition and are dependent on the patients' condition and their response to therapy (Preston and Kelly, 2017).
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Use
There are various conditions that necessitate the use of NPPV:
In NPPV, a secure-fitting mask is used as the interface between the patient and the ventilator, thus avoiding complications associated with other forms of interface, such as tracheostomy (Hilbert et al, 2008). The use of the mask in NPPV leaves the upper airway complete in comparison to the use of endotracheal systems, thus preserving the airway's defence mechanisms; further, the use of the mask allows patients to eat, drink, talk and expectorate secretions (Brill, 2014).
The goals of NPPV differ according to the clinical context (Hilbert et al, 2008). Before therapy is started, its benefits should be discussed with patients. This is especially prudent in the case of COPD or neuromuscular conditions, where NPPV is being used to support the work of breathing and palliate patient symptoms (Halliwell, 2016). Long-term use of NPPV aims at reversing hypercapnia and hypercapnic respiratory failure, thereby reducing hospital admissions with acute type 2 respiratory failure and improving quality of life (Murphy et al, 2017). NPPV at home is deemed to have failed when the patient's respiratory failure continues to progress despite the therapy (Brill, 2014). Regular review by a specialised healthcare practitioner is therefore required. This may be a respiratory specialist nurse or a respiratory consultant, depending on local service provision, and take place either in the home environment or a secondary care setting. Ando et al (2014) suggested that some patient groups psychologically struggle with NPPV therapy. For example, they found that understanding the psychological impact of NPPV in the short and long term is particularly important in the case of patients with motor neurone disease. Similarly, Tissot et al (2015) found that older adults using NPPV for 6 months failed to show improvements in quality of life. Thus, the pathophysiological reason and rate of disease deterioration, rather than the use of ventilation, are indicative of the prognosis for many patients.
Some of the reasons cited by patients for not using NPPV therapy are the noisiness of the machine, feeling more breathless, conjunctivitis, excessively high pressure causing discomfort during use, headaches and sleep disturbance (Cheng et al, 2012).
Depending on their condition, patients may have a perceived improvement in quality of life when NPPV is introduced and used for a few weeks (Shneerson, 2012; Simonds, 2012; Baxter et al, 2013; Gale et al, 2015). For some, this therapy changes as their disease progresses, for example, patients with neuromuscular disease may increase NPPV use with disease progression. Health professionals need to understand that NPPV systems are cumbersome and may not have the desired effect that the patient wishes or that the effect of therapy may change with time. For example, patients with neuromuscular conditions could go from overnight use to use during the day and night (Shneerson, 2012; Baxter et al, 2013). After a while, patients may bring up the possibility of reducing use and the impact this would have on quality and quantity of life (Bridge et al, 2013). Patients with motor neurone disease are reported as experiencing reduced anxiety and discomfort when NPPV is used in the end-of-life phase of disease (Baxter et al, 2013). Patient-perceived benefit is an important factor in therapy compliance (Baxter et al, 2013). For a select group of patients with COPD, using this therapy overnight may have the benefit of reducing exacerbation and readmission rates, although there is little evidence to suggest that NPPV therapy changes the mortality rate in these individuals (Murphy et al, 2017). Because of the gradual onset of COPD symptoms, the multiple associated co-morbidities and poor understanding of the disease process, many patients fail to understand that their condition is life-limiting (Gott et al, 2009). It should be recognised that some patients using ventilation therapies are at a point where consideration should be given to the introduction and development of anticipatory care plans and an understanding of patients' long-term wishes should be highlighted (Baxter et al, 2013; Gale et al, 2015). This is especially important in the case of COPD and neuro-muscular disorders when NPPV is being used as supportive end-of-life therapy (Baxter et al, 2013).
Interface—mask or nasal pillows (cannula)
There are a significant number of mask types and various different equipment manufacturers. It is important for community nurses to be clear about what equipment the patient is using, ensure replacements and ensure that discussions about equipment are appropriate for the individual patient. For example, some facemasks have ports to entrain oxygen while others do not. Training, education and support around the interface play an important role in ensuring patients can manage and comply with therapy (Eng, 2006; Scaffardi et al, 2013). While the therapy is well tolerated once the patient has adjusted to the sensation of the pressures, it needs to be managed, especially at the beginning; this will improve acceptance of the therapy and thus aid compliance (Brill, 2014).
NPPV can be administered to patients through numerous different types of interfaces: face masks that cover the nose and mouth (full-face mask or oronasal mask); nasal masks, which cover the nose area and leave the mouth free; and ‘nasal pillows’ that fit into the nostrils (Figure 1) (Hilbert et al, 2008; Preston and Kelly, 2017). In the home environment, the interfaces most commonly used are a full-face or nasal mask secured firmly, but not tightly, with a head-strap (Figure 2; Brill, 2014). Understanding the principles of mask fitting can help reduce problems such as skin necrosis associated with a poorly fitting interface and can maximise comfort (Brill, 2014). The choice of mask type mostly depends on the patient's ability to use it and comfort they experience.
Full-face mask
The full-face mask allows delivery of higher ventilation pressures with patients experiencing a smaller quantity of leak (air loss through the mask or mouth), and it permits mouth breathing (Hilbert et al, 2008). Thus, overall ventilation is improved, as a leak or poor mask fit would mean that the IPAP and EPAP are less effective. However, the full-face mask is considered less comfortable, and it could ventilate the mouth and cheeks thereby increasing the ‘dead space’ (Basner, 2015). It can also hamper communication as it covers the mouth (Baxter et al, 2013) and potentially restrict oral intake (Hilbert et al, 2008), especially if the therapy is administered during the day. Carers may struggle to maintain oral hygiene, especially if the patient is using the therapy for significant lengths of time during the day and has reduced oral intake. Patients also complain that the full-face mask can feel claustrophobic (Baxter et al, 2013; Credland, 2013). They are also at risk of aspiration if they vomit and are unable to remove the mask independently. Lastly, gastric distention associated with patients who experience excessive air swallowing (aerophagia) during therapy can be a troublesome long-term side effect (Basner, 2015).
Nasal mask
Nasal masks necessitate a patent nasal passage and require the mouth to be closed when in use in order to minimise air leak, which some patients can find challenging. Leaks through the mouth decrease alveolar ventilation and may decrease the efficacy of NPPV, although research has suggested that if chosen appropriately, the interface should not limit clinical efficacy (Brill, 2014). Navalesi et al (2000) suggested that when masks are used for prolonged durations, the nasal mask is preferred. In contrast, Brill (2014) suggested that nasal pillows may be more comfortable.
Some good practice points related to the use of these interfaces are as follows:
NPPV ports
In the home environment, the masks or hose have a port to allow the entraining of oxygen therapy. When oxygen is not being used, these ports need to be closed. Some ventilator machines also contain oxygen-entraining ports. Oxygen will be titrated on initiation to reach a target saturation that is appropriate for that patient depending on their condition (O'Driscoll et al, 2017).
Masks have an exhalation port that is designed to allow carbon dioxide to escape from the system to limit the possibility of the patient re-breathing it, and these should always be left uncovered (Brill, 2014; Selim et al, 2018). The only area around the mask or hose where any movement of air or gases should be felt is where there are exhalation ports, and it is important to regularly check there is still air flow through these (Brill, 2014). It is also important to understand that patients may use different mask systems in hospital from those provided for long-term use, and they may verbalise the differences in air movement that they experience.
Air leaks
Air leaks around the mask or from the mouth limit the efficacy of the device and interface. Air leaks can potentially prevent adequate ventilatory assistance in patients, especially those who require high IPAPs. Air leak is often a cause of therapy failure: it causes noise, which disturbs sleep, and therefore appropriate fitting of the mask is an important part of managing the therapy (Brill, 2014).
Most ventilatory machines will sound an alarm and compensate for a leak if set appropriately. Leaks can also be heard (Brill, 2014). Once the mask is fitted and the machine turned on, it is advisable to gently feel around the mask to assess if small leaks are present. A common place for mask leak is around the eyes, and this can cause conjunctivitis and eye irritation and therefore should be carefully monitored (Brill, 2014; Credland, 2013; Hilbert et al, 2008). Irrespective of the type, a well-fitted mask should not impinge on the corners of the eyes or lips (Brill, 2014).
Leaks can also occur if the mask is fitted with the patient's dentures in, as the shape of their face changes when the dentures are removed. It is important to ensure that patients understand the importance of maintaining their face shape with their dentures when wearing the mask. The shape of the face may also change if the patient changes their position from the one in which the mask was fitted. For example, the face changes shape from sitting to lying, and masks should be fitted with the patient in the position they are most likely to be receiving therapy in, which is usually lying down. When looking after a patient at home, this will need to be taken into consideration if patients' positions are changed for comfort.
Another situation in which leaks are common is when patients have beards. The mask cannot fit snugly on to the contours of a face covered by a beard. Mask fit can be ensured by having the patient clean shaven. It is important to remember if the patient chooses not to shave, the additional facial hair will affect mask fit and consequently, the therapeutic efficacy.
Head straps provide a mechanism for securing the mask and are designed to work with a specific mask (Figure 3; Hilbert et al, 2008). Movement and adjustment of the supporting straps around the patient's head can change the fit of the mask and reduce leaks (Brill, 2014). Attachment systems, including magnetic or Velcro attachments, have been developed to help preserve patient independence and maintain patient comfort. Chin straps can support the chin if the patient struggles to keep their mouth closed. An open mouth will reduce the efficacy of the therapy, as it allows some air to escape. However, Brill (2014) suggested that patients may find a chin strap uncomfortable.
The reusable home equipment for NPPV systems lasts for approximately 6–12 months, depending on how well the components are taken care of (according to the manufacturers' instructions). For example, head straps can stretch and cause the mask to become ill fitting. The patient's skin leaves a residue on the mask and straps, and it is important that they are cleaned regularly. The mask should be cleaned according to the manufacturer's instructions to maintain its integrity and durability.
The following good practice points should be noted with regard to leaks:
Facial skin breakdown
While complications with NPPV tend to be minor, Mottard et al (2014) reported that up to 50% of patients may experience skin breakdown. Both nasal and full-face masks can cause pressure necrosis of the skin over the nasal bridge if fitted too tightly (Hilbert et al, 2008; Mottard et al, 2014). Avoiding this complication requires careful attention in the mask selection process and involves using cushioning materials and ‘rest’ periods if the patient is using the therapy during the day, to help reduce the pressure on the bridge of the nose (Hilbert et al, 2008; Brill, 2014). Mask fit is therefore a fundamental aspect of NPPV therapy. The cushion on the mask that is in contact with the skin occasionally reacts with the skin and causes a rash (Brill, 2014). The mask may need to be changed then, so patients should be directed to discuss this with specialised healthcare practitioners. Protective creams are not recommended, as they affect the integrity of the mask. Ongoing monitoring of the nasal bridge by the patient or carer is helpful, as prevention of pressure sores will promote compliance and reduce discomfort created by skin necrosis (Brill, 2014). Other factors such as underlying comorbidities also affect the integrity of the skin (Brill, 2014). A change of interface may be warranted if the patient is starting to develop skin breakdown. Use of pressure dressings to reduce the pressure on the bridge of the nose may be helpful but again, could affect the fit of the interface (Eng, 2006; Brill, 2014).
Ensuring that there is minimal friction and pressure from the mask and regular skin protection are important factors for reducing the occurrence of skin breakdown. It is important to keep the mask in place, using the minimum amount of pressure possible while maintaining the efficacy of the therapy (Brill, 2014).
Some good practice points to bear in mind are as follows:
Dexterity
Patient dexterity can change over time and where a person could previously manage their mask fitting, they may start to struggle with the tightness or general comfort. Different fastenings can help ease the struggles associated with fitting, for example, Velcro or magnetic fastenings. Monitoring the patient's ability to fit and remove the mask is an important part of care, as interface fit affects the efficacy of therapy.
Ventilators
Ventilators employed for long-term use at home are usually lightweight, free-standing devices with limited alarm systems that have been specifically designed for non-invasive respiratory support (Figure 4).
Newer systems can relay data to the supporting specialist health professionals to allow understanding of device compliance. They also have features to allow the machine pressures to be altered remotely, thereby allowing titration of therapy while the patient remains at home. Aspects such as leakage from the system can also be reviewed, so discussion with the specialist NPPV team may help ensure and give reassurance that patients are receiving the most effective therapy. Some long-term ventilators do not use remote monitoring systems. For these, the pressures are set at the optimum level, and this helps maintain stability and levels that the patient can tolerate. These are likely to only be adjusted when a patient is reviewed.
Ventilator devices do need ongoing care: they should be cleaned and the external filters should be changed according to the manufacturer's instructions. Patients and carers should be advised of the machines' requirements as part of the education and set-up process.
Humidification
Some patients experience dryness of the mouth (xerostomia) or nose, associated with high pressures of air or air and oxygen combinations that are being driven into the patient by the ventilator (Brill, 2014; Gale et al, 2015). This can be reduced with the use of protective creams for the lips and nasal passages. Care needs to be taken with the protective creams that are recommended, as creams with high amounts of petroleum are not suitable (Hardinge et al, 2015). Water-based creams are preferred, and checking the ingredients is good practice. If creams are not effective, then the use of humidification units attached to the ventilator can help some patients. These units require cleaning on a daily basis. They should be left to dry and then filled with cooled boiled water to reduce contamination (per the manufacturer's instructions). Recognising that a patient is experiencing problems such as dry mouth, epistaxis or rhinitis is important, as all of these can be resolved with the introduction of humidification (Strollo and Coleman, 2015). The use of a humidification unit may also mean that the hose needs to be changed to provide a heating element, as this reduces the amount of ‘rainout’ that occurs with the humidified air travelling through the hose to the patient. A cold hose causes the air to cool down more rapidly and create water droplets in the hose.
Backup and support
Some ventilators are provided with a backup battery, and some specialist areas provide additional ventilator machines especially for conditions where the patient will quickly deteriorate or symptomatically become uncomfortable if the therapy is not available, for example, some neurological conditions. There are, however, some conditions, such as obesity hypoventilation, where occasional failure to use the therapy is unlikely to be severely detrimental to the patient. It is important to ensure there is an understanding of accessibility of back up or replacement systems so that patient safety is maintained and carers and health professionals feel supported. Different areas will have different support processes in place, so understanding and documenting local processes is important. As a good practice point, nurses should ensure that patients and carers are aware of where to access new equipment.
Conclusion
NPPV is used in a number of different conditions that are associated with chronic type 2 respiratory failure. It is becoming common for this therapy to be administered within the home environment. Therefore, it is important that heathcare practitioners understand the principles of the NPPV therapy, its use and the challenges it can present for patients. Some vital aspects that need consideration include the importance of good mask fit, the complications that patients can experience with the therapy and how these influence its efficacy. Thereby, nurses can improve how the patient's care is managed within the home environment. Nurses developing specialist knowledge and understanding of NPPV within the home environment will promote patient compliance and reduce hospital admissions and complications from NPPV therapy.