**6. Selection of interface**

Interfaces connect the patient's airway to the NPPV tubing. The main six interfaces for NPPV are nasal mask, full face or oronasal mask, total face mask, helmet mask, nasal pillow or plugs and mouthpieces. Usually made of silicone, masks need to be carefully fitted to the individual to obtain optimum results. Variations include the bubble-type mask, and gel masks. Mask fit can be enhanced using mask cushions and seal/support rings which are supplied with the mask.

**Nasal mask:** Nasal mask covers nose and does not cover mouth so allows speaking, drinking and cough also reduces the risk of vomiting and asphyxia. Disadvantages of nasal masks are air leaks if mouth opens, possible nasal skin damage and the need for patent nasal passages.

**Oronasal /Full face mask:** Oronasal mask cover the nose and mouth and can prove valuable in patients with nasal airway blockage or acute confusional state. Oronasal mask is

Noninvasive Positive-Pressure Ventilation Therapy in Patients with COPD 343

12. Monitor comfort, respiratory rate, oxygen saturation and dyspnea every 30 minute for

Predictors of NPPV failure are no improvement or a fall in pH and PC02, no change or a rise in breathing frequency after 1-2 hours and lack of cooperation. Delays in intubation of these patients run the risk of unanticipated respiratory or cardiac arrest with attended morbidity and mortality. NPPV failure occurs more frequently in the first hours of ventilation, and was reported to be predicted by the following clinical factors: severe acidosis, high severity score, severe impairment of consciousness, presence of co-morbidities and lack of improvement of arterial blood gases after 1-2 hours of initial ventilation (Ambrosino et al.

Complications of NPPV therapy are minor and preventable. Major complications of NPPV such as pneumothorax and pneumocephalus are so rare (Grunstein 2005). The most common complications effecting almost half of the patients who are administered NPPV are due to mask leak and/or mask pressure injury (Pepin et al. 1999; Hoffstein et al. 1992; Abisheganaden et al. 1998; Lojander, Brander, & Ammala 1999; Sanders, Gruendl, & Rogers

Rhinitis, Rhinorrhea

Anxiety Dry mucous membranes and thick secretions

Chest pain Barotrauma (pneumothorax, pneumocephalus)

pressure

Hypotension related to positive intrathoracic

1986). The main complications of NPPV therapy are listed in Table 2.

Insomnia Aspiration of gastric contents

**Due to Mask Due to Device** 

**General** Gastric distension

Headache Central Sleep Apnea

Mask allergy Sinusitis Conjunctivitis Tinnitus Dermatitis Otitis /ear pain Claustrophobia Epistaxis

13. Measure arterial blood gases at baseline and within 1 hour from the start.

duration should be as short as possible. 10. Protect site of skin pressure from the interface.

6-12 hours and then hourly.

1995; Elliott 2002; Nava & Ceriana 2004)

**8. Complications of NPPV** 

Facial and nasal pressure injury/

ulcerations / pain

Periodic Legs Movement

Table 2. Complications of NPPV Therapy

Syndrome

11. Consider use of mild sedation if the patient is agitated.

14. Humidification is advised for longer application.

are 4 cm H20 and 20 cm H20, respectively. PS should be increased in order to optimize CO2 removal and control of auto-positive end expiratory pressure (PEEP), according to the patient's tolerance. A backup rate (ST mode) should be used in all patients with low respiratory rate, in patients who unreliably trigger IPAP/EPAP cycle due to muscle weakness and in patients who do not achieve adequate ventilation or respiratory muscle rest with the maximum tolerated PS in the spontaneous mode. The inspiratory

recommended rather than nasal mask in patients who have ARF. Although there was no difference in endotracheal intubation or mortality rates, the oronasal mask was better tolerated (Keenan et al. 2011). The use of an oronasal mask seem a logical solution to maximize the NPPV efficacy, presumably due to lower leakage with oronasal mask compared to nasal mask in dyspneic patients who are mostly mouth-breathers (Carrey, Gottfried, & Levy 1990). However during long-term use the face mask can be poorly tolerated, thus causing a premature NPPV interruption (Carlucci et al. 2001).

**Total face mask:** Total face mask covers mouth, nose and eyes. Advantages of this type of masks are minor air leaks, little cooperation required and easy fitting application. Risks of asphyxia, claustrophobia, speaking difficulty are the main disadvantages.

**Helmet:** Helmet mask covers whole head and all or part of the neck without a contact with face. Advantages of this type of masks are minor air leaks, little cooperation required and absence of nasal or facial skin damage. The risk of vomiting, worsening of C02 clearance due to rebreathing, asynchrony with pressure support ventilation and discomfort of axillae are the disadvantages of the helmet.

**Nasal pillow or plugs:** These masks are inserted into the nostrils. This type of the mask may be suitable for claustrophobic patients with chronic stable COPD who do not need high pressures. Nasal irritation is the main disadvantage.

**Mouthpieces:** They are placed between lips and held in place by lip seal. Mouthpieces can be applied with other interfaces. The risk of vomiting and salivation, possible air leaks, gastric distension and speaking difficulty are the disadvantages of the mouthpieces. Mouthpiece ventilation is mainly used in patients with neuromuscular disease.
