Noninvasive positive pressure ventilation (NPPV) has been a popular topic of research studies. Multiple studies have shown it to be a preferred treatment option for patients with chronic obstructive pulmonary disease (COPD), as well as for those suffering from acute hypoxemic respiratory failure. Recent research also supports the use of NPPV as a successful tool to facilitate weaning from invasive mechanical ventilation, for both removing a patient from mechanical ventilation sooner and providing support for patients who ultimately fail extubation. NPPV may be a reasonable alternative for a patient who is at risk of failing extubation, or for the patient who does not meet all of the typical requirements for extubation.
Although invasive mechanical ventilation (MV) is a highly effective lifesaving procedure, it has the potential for producing many undesirable side effects. Invasive mechanical ventilation has been associated with ventilator-acquired pneumonia, resulting in associated high mortality rate, sinusitis, longer stays in the intensive care unit (ICU), lengthy hospital stays, and higher overall costs.1-5 Patients who fail to be liberated from the ventilator undergo costly hospital stays and have higher rates of mortality, sometimes as a result of consensual withdrawal of life support.
Researchers have reported that high levels of post-traumatic stress disorder symptoms are seen in one out of seven patients, 6 months following MV.6 Invasive mechanical ventilation is also a very time-intensive and expensive treatment for hospitals.7 In one study,8 the costs associated with invasive mechanical ventilation were approximately $1,190/day versus $191/day for NPPV.
Choosing the Right Patients
It is important to identify the patients who might be at a higher risk for extubation failure and who might benefit from NPPV. Research studies have demonstrated that the greatest success for NPPV has been experienced with COPD patients.9-20 The research also supports that the earlier a patient is removed from a mechanical ventilator, the higher the probability that they will be able to avoid complications, and the more likely they are to have a cost-effective method of treatment.
In a multicenter, randomized trial by Nava et al,9 a group of COPD patients with acute hypercapnic respiratory failure who were intubated for 48 hours were put on a spontaneous breathing trial (SBT). Patients who failed the weaning attempt were randomized either to receive NPPV by face mask following extubation or to remain intubated and continue receiving invasive mechanical ventilation. A follow-up of these patients 60 days later showed that the patients who received NPPV had a shorter weaning time, reduced time in the intensive care unit, a reduced incidence of nosocomial pneumonia, and improved survival rates (see Table).
In a multicenter, randomized controlled study in 2005 by Nava et al,10 a group of patients believed to be at risk of developing postextubation respiratory failure received either standard medical care or noninvasive ventilation. The NPPV group had a lower rein-tubation rate and a reduced mortality rate. The authors concluded that noninvasive ventilation was more effective in the prevention of postextubation respiratory failure than were standard methods.
Timing Is Everything
The keys to success with noninvasive ventilation may rest not only with proper patient selection, but also with the timing of decision-making. Knowing when to start NPPV, and likewise knowing when to stop NPPV, in a patient who is failing and requires intubation are both critical components to achieving positive outcomes. Using the appropriate ventilator and interface is also an important factor. Research has suggested that the sooner a patient is placed on NPPV after extubation, the better the chance of success. NPPV failure was most often seen when patients had already failed extubation and were in respiratory distress and failure before they were placed on NPPV. It should also be noted that many of the patients who failed noninvasive ventilation were classified as non-COPD patients.20-21 In a study by Esteban et al,21 which showed that patients who were placed on NPPV following the development of postextubation respiratory failure had an increased mortality rate compared to patients who were intubated, it appeared that in some cases there may have been a delay in making the decision to stop NPPV and intubate the patient, which resulted in a negative outcome. In this same study, although it was somewhat unclear as to the exact equipment used, it was suggested that a critical care ventilator was utilized with a “tight fitting face mask.” Patient comfort is a key component to success with NPPV, and although many of the current generation ventilators have begun incorporating noninvasive ventilation modes, these were likely not available when the Esteban research was performed. Another question that the authors themselves raised was related to the fact that their research included only a small number (10%) of COPD patients, the one group of patients for whom NPPV has been shown to be the most beneficial.
Good Outcomes with NPPV
Noninvasive positive pressure ventilation has been associated with higher survival rates and reductions of nosocomial infections.22 Weaning patients from MV and avoiding reintubation are both very important aspects of total patient care. The physiological principle behind using NPPV as a tool to wean patients from mechanical ventilatory support and as a method to prevent the need for reintubation is the manner in which NPPV can balance out the large negative deflections in intrathoracic pressures that are observed when patients are taken off mechanical ventilation.23 NPPV appears to increase the alveolar ventilation by attaining a slower and deeper breathing pattern. This results in a reduction in the work of breathing and improved ABG levels, therefore allowing for a better rate of success in patients following extubation.
Considering difficult to wean COPD patients, NPPV may provide an excellent option that benefits both the patient and the hospital. As mentioned previously, mechanical ventilation provided in the intensive care unit is extremely costly and requires a high level of resources. With proper monitoring and administration of the therapy by experienced clinicians, NPPV may be provided outside of the ICU for select patients.
One of the most exciting benefits of NPPV over MV is the ease with which patients can be removed from the system. Simply removing the interface (mask) to observe the patient’s ability to breathe without it creates a much easier method of weaning, when compared to the process of removing and possibly reinserting an endotracheal tube.
Kristie Mitton is an MS-RT student at Northeastern University, and is employed in the Respiratory Care Department; Paul Nuccio, RRT, FAARC, is director of respiratory care at Brigham and Women’s Hospital in Boston.
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- Heyland DK, Cook DJ, Griffith L, Keenan SP, Brun-Buisson C. The attributable morbidity and mortality of ventilator-associated pneumonia in the critically ill patient. The Canadian Critical Care Trials Group. Am J Respir Crit Care Med. 1999;159:249-56.
- Bigatello LM, Stelfox HT, Berra L, Schmidt U, Gettings EM. Outcome of patients undergoing prolonged mechanical ventilation after critical illness. Crit Care Med. 2007;35:1-7.
- Girard TD, Shintani AK, Jackson JC, et al. Risk factors for post-traumatic stress disorder symptoms following critical illness requiring mechanical ventilation: a prospective cohorts study. Crit Care. 2007;111:1-8.
- Cox CE, Carson SS, Govert JA, Chelluri L, Sanders GD. An economic evaluation of prolonged mechanical ventilation. Crit Care Med. 2007;35:1918-27.
- Plant PC, Owen JL, Parrott S, Elliott MW. Cost effectiveness of ward based non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease: economic analysis of randomized controlled trial. BMJ. 2003;326:956.
- Nava S, Ambrosino N, Clini E, et al. Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease. Ann Intern Med. 1998;128:721-8.
- Nava S, Gregoretti C, Fanfulla F, et al. Noninvasive ventilation to prevent respiratory failure after extubation in high risk patients. Crit Care Med. 2005;33:2465-70.
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- Keenan SP, Powers C, McCormack DG, Block G. Noninvasive positive-pressure ventilation for postextubation respiratory distress: a randomized controlled trial. JAMA. 2002;287:3238-3244.
- Esteban A, Vivar-Frutos F, Ferguson N, et al. Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med. 2004;350:2452-60.
- Girou E, Schortgen F, Delclaux C, et al. Association of noninvasive ventilation with nosocomial infections and survival in critically ill patients. JAMA. 2000;284:2361-7.
- Vitacca M, Ambrosino N, Clini E, et al. Physiological response to pressure support ventilation delivered before and after extubation in patients not capable of totally spontaneous autonomous breathing. Am J Respir Crit Care Med. 2001;164:638-41.