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Where to perform noninvasive ventilation?

¹ St James's University Hospital, Leeds, UK, ² Dept of Pneumology, Hospital of Trieste, Trieste and ³ Respiratory Unit, Fondazione S.Maugeri, Pavia, Italy

CORRESPONDENCE: M. Elliott, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK. Fax: 44 1132066042. E-mail: mark_w.elliott@leedsth.NHS.UK

Keywords: High dependency unit, intensive care unit, noninvasive positive-pressure ventilation

Received: May 21, 2001
Accepted November 22, 2001

Abstract

Noninvasive positive-pressure ventilation (NPPV) has been shown to be a means of reducing the need for endotracheal intubation, which when effective reduces the complication rate and improves outcome. Because paralysis and sedation are not needed and because the patient is not necessarily dependent upon a machine for respiration, ventilation outside the intensive care unit (ICU) is an option. A number of studies have shown that NPPV for acute exacerbations of chronic obstructive pulmonary disease (COPD) can be effective in the non-ICU environment, though usually in patients with less severe exacerbations. However, there have been no direct comparisons of the application of NPPV in different locations.

The likelihood of success of the technique is an important factor in deciding where NPPV should be performed. Ready access to invasive ventilation is important when NPPV is not indicated from the outset or fails after an initial trial. In acute exacerbations of COPD, NPPV is less likely to be successful the more severe the exacerbation, as measured by the severity of acidosis. Good tolerance of NPPV, which translates into an improvement in pH and a fall in respiratory rate, predicts a successful outcome and is a useful way of monitoring progress.

NPPV has been shown to be cost effective both in the ICU and when performed on general wards. A dedicated intermediate care unit with particular expertise in noninvasive modes of ventilation may provide the best environment, both in terms of outcome, but also cost effectiveness.

The ideal location for noninvasive positive-pressure ventilation will vary from country to country and indeed from hospital to hospital, depending upon local factors. However, the most important factor is that staff be adequately trained in the technique and be available throughout the 24-h period.

Noninvasive positive-pressure ventilation (NPPV) has been shown to be an effective treatment for ventilatory failure, particularly resulting from acute exacerbations of chronic obstructive pulmonary disease (COPD) 1–10, but also hypoxaemic respiratory failure 11, community acquired pneumonia 12, cardiogenic pulmonary oedema 13, 14, following solid organ transplants 15, and in immunocompromised patients 16 in 16 randomized-controlled trials (RCTs). There have also been two RCTs of NPPV in weaning 17, 18. These studies have been performed in a variety of different countries in varying ward environments and have established NPPV as an important tool in the management of patients with respiratory failure.

Definitions

In any discussion concerning the location of an acute NPPV service it is important to note that the model of hospital care differs from country to country and that the "intensive care unit" (ICU), "high dependency unit (HDU)" and "general ward" will have different levels of staffing, facilities for monitoring etc. Therefore, care must be taken in the extrapolation of results obtained in one study environment to other hospitals and countries. The UK King's Fund panel 19 have defined intensive care as: "A service for patients with potentially recoverable diseases who can benefit from more detailed observation and treatment than is generally available in the standard wards and departments". Unfortunately, this broad definition does not assist in the problem of comparisons of individual ICUs between studies. The definition of HDU is even less clear with some HDUs allowing invasive monitoring whilst in others only noninvasive monitoring is performed. In some countries specific respiratory ICUs and intermediate ICUs have been developed.

For the purpose of this article the following definitions were used. ICU: a high ratio of staff to patients and facilities for invasive ventilation and monitoring; intermediate respiratory ICU or HDU: continuous monitoring of vital signs in a specified clinical area with a staffing ratio between an ICU and a general ward; general ward: unselected emergency admissions taken and therefore although most have a particular speciality interest, patients with a variety of conditions and degrees of severity are cared for in the same clinical area. Variable nurse staffing levels but not as intensive as HDUs and ICUs.

These definitions are based largely on staffing levels but the types of ventilator which are available within and outside the ICU also vary and may have an important effect upon the effectiveness of NPPV. The ability to deliver a high inspiratory oxygen fraction (F_I,O2) is of particular relevance in patients with hypoxaemic respiratory failure. Most portable ventilators do not have a gas blender and therefore it is impossible to deliver a high F_I,O2. In addition the operator does not know exactly what concentration of oxygen the patient is receiving. The principal limitation to the use of home ventilators during acute respiratory failure (ARF) is the lack of direct "on-line" monitoring of pressure, volume and flow provided by these devices. The evaluation of patient-ventilator asynchrony is very difficult if not impossible without visualization of flow and pressure waveforms 20. These are important features, especially during the first period of ventilation when it is important to assess the patient-ventilator interaction, respiratory mechanics, and the expired tidal volume (V_T) 21. A bench study has recently demonstrated the inaccuracy of V_T delivered by some home mechanical ventilators when the pressure imposed on the ventilator is increased to simulate high airway resistance 22. In other words, some of the commercially available devices fail to provide the desired V_T constantly during volume ventilation. This represents an evident limit on the use of these devices when the respiratory load is greatly increased as is the case in some patients with ARF. Newer ventilators specifically designed for NPPV in the hospital environment for patients with ARF overcome some of these problems.

Evidence for different locations for an acute noninvasive ventilation service

Chronic obstructive pulmonary disease
Most RCTs have studied patients with COPD and are therefore the main focus of this discussion. Early RCTs comparing NPPV with conventional therapy in the ICU showed that successful NPPV is possible. Most striking was the reduction in the need for intubation 2, 3, which in the largest study translated into improved survival and reduced length of both ICU and hospital stays 2. Complications, particularly pneumonia and other infectious complications were markedly reduced 2, 11, 15, 17. These studies were performed in units committed to the noninvasive approach and with particular expertize and this factor more than any other may have been important in determining the outcome. However, these studies do show that NPPV is feasible and, when successfully applied, effective.

The use of NPPV opens up new opportunities for the management of patients with ventilatory failure with regard to location. With NPPV paralysis and sedation are not needed and ventilation outside the ICU is an option. Treatment outside the ICU is an attractive option given the considerable pressure on ICU beds in some countries, the high costs and that for some patients admission to ICU is a distressing experience 23.

There have been a number of prospective randomized controlled studies of NPPV outside the ICU 1, 4–6, 8. These studies showed varying results with none providing a conclusive statement on the role of NPPV, largely because the studies lacked sufficient statistical power. In the largest study (n=236), performed in general respiratory wards in 13 centres, NPPV was applied by the usual ward staff using a bilevel device in the spontaneous mode according to a simple protocol 10. This was powered to pick up a 50% difference in "treatment failure", a surrogate for the need for intubation, defined by a priori criteria. Treatment failure was reduced from 27% to 15% by NPPV (p<0.05) and in-hospital mortality was also reduced from 20% to 10% (p<0.05). Subgroup analysis suggested that the outcome in patients with pH <7.3 after initial treatment was inferior to that in the studies performed in the ICU. It should be appreciated that it was not just location which differed between the ICU studies and this one; a very simple ventilator was used according to a protocol compared with more sophisticated individually adjusted ventilation in the ICU studies. However, this study does suggest that with adequate staff training NPPV can be applied with benefit outside the ICU by the usual ward staff and that early introduction of NPPV on a general ward results in a better outcome than providing no ventilatory support for acidotic patients outside the ICU. The study certainly does not suggest that NPPV should be performed on a general ward in preference to an ICU or a higher-dependency setting.

Conditions other than chronic obstructive pulmonary disease
There are no RCTs of NPPV outside the ICU in hypoxaemic respiratory failure or weaning and it is therefore only in patients with exacerbations of COPD that there is an evidence base for NPPV use outside of the ICU. The study of Antonelli et al. 11 in which conventional mechanical ventilation and NPPV were compared in patients with acute hypoxic respiratory failure, showed NPPV to be as effective as conventional ventilation at improving gas exchange. Patients receiving NPPV had significantly lower rates of serious complications and those successfully treated with NPPV had shorter ICU stays. Post hoc subgroup analysis of patients with simplified acute physiological scores (SAPS) of <16 and those of 16 showed that patients in the latter group had similar outcomes irrespective of the type of ventilation. However, NPPV was superior to conventional mechanical ventilation in patients with SAPS <16.

As with acute exacerbations of COPD it would therefore appear that it is possible to successfully manage patients with milder disease with NPPV. Further data are needed but it would be reasonable for selected patients to have a trial of NPPV on an experienced noninvasive unit outside the ICU, although rapid access to intubation and mechanical ventilation must be available.

Should noninvasive ventilation be started in the emergency department?

The type of treatment that is undertaken in the the emergency department and the length of time that patients typically stay there varies from hospital to hospital and from country to country. In some, patients remain in the emergency department for a very short period whereas in others they may remain there for a day or more. Two studies in which NPPV was initiated in the emergency department 4, 6 both failed to show any advantage to NPPV over conventional therapy. There are a number of possible explanations for this, which include the fact that patients are usually admitted to the ICU when other therapies have failed whereas most of those presenting to the emergency department have not received any treatment and therefore a proportion are going to improve after initiation of standard medical therapy. In a 1-yr period prevalence study 24, 20% of 983 patients with acute exacerbations of COPD were acidotic on arrival at the emergency department in Leeds and of these 20% had completely corrected their pH by the time of arrival on the ward. There was a weak relationship between the oxygen tension in arterial blood on arrival at hospital and the presence of acidosis, suggesting that in at least some patients respiratory acidosis had been precipitated by high-flow oxygen therapy administered in the ambulance on the way to hospital. It is important to note that the only study that showed an unequivocal benefit from NPPV outside the ICU 10 recruited patients who remained acidotic and tachypnoeic on arrival on the ward after treatment in the emergency department. The need for rapid access to facilities for intubation and mechanical ventilation is an important message from the negative study of Wood et al. 6, in which there was a trend towards worse outcome with NPPV, which was attributed in part to delays in intubation in the NPPV group. It should also be noted that this was a mixed population of patients and the two groups were not well matched hence this may also have explained some of the differences. Further potential problems relating to the provision of NPPV in the emergency department include the wide heterogeneity of disorders treated there; staff need to be skilled in the management of disorders of many different organ systems and it may not be possible to train them adequately in NPPV given the many other demands placed upon them. Furthermore, COPD patients with acute ventilatory failure need a longer length of stay to recover a stable status than that generally available in the emergency department.

NPPV has been shown to be of benefit in patients with cardiogenic pulmonary oedema (CPO) 13, 14, 25 and if NPPV is to be administered to these patients it needs to be early on after admission, which will usually mean in the emergency department. Continuous positive airway pressure (CPAP) is the usual mode of choice, but it is important that ventilators capable of delivering a high F_I,O2 be available for when NPPV is necessary.

There are some patients with a variety of aetiologies for respiratory failure who present to the emergency department in extremis and require immediate ventilatory support, for whom intubation is not considered appropriate. This could be because the patient's previous history is well known or they have made an advance directive precluding intubation and mechanical ventilation. In these patients a trial of NPPV could be considered. In this situation it would be reasonable to start NPPV in the emergency department in order to stabilize the patient for transfer to the ward on which NPPV is normally performed. In other patients where the clinical findings suggest that intubation would not be appropriate, but the medical notes or a family member are not available, NPPV can be used to buy time to obtain further information or to allow the patient to recover to the point at which they can make their opinion about their future management known. However if there is no improvement the patient should be intubated and transferred to the ICU.

In summary, most patients presenting to an emergency department with an acute exacerbation of COPD do not need NPPV, but particular attention should be paid to controlled oxygen therapy. NPPV may be needed in a few patients who are in extremis and for whom intubation is not considered appropriate. If it is normal policy for patients to receive the first 24-h treatment in the emergency department, then NPPV should be started there in those who remain acidotic and tachypnoeic a short time after standard medication has been administered and oxygen therapy optimized. Noninvasive CPAP or bilevel ventilation for patients with acute CPO will usually be delivered in the emergency department. For these reasons it is necessary for staff working in the emergency department to be trained in, and to develop skills in NPPV. This may best be achieved by attachment and rotation through the unit providing the major focus for NPPV in the institution.

Where should noninvasive positive-pressure ventilation be performed?

Factors which need to be considered when deciding where NPPV should be performed are summarized in table 1. There have been no direct comparisons between outcome from NPPV in the ICU, in intermediate units and on a general ward and it is unlikely that there ever will be such a trial. It should be appreciated that while there is some overlap, the skills needed for NPPV are different to those required for invasive ventilation and the outcome from NPPV is likely to be better on a general ward where the staff have a lot of experience of NPPV than on an ICU with high nurse, therapist and doctor to patient ratios and a high level of monitoring, but little experience of NPPV. The patient's perspective is also important; many find their experience of ICU to be unpleasant 23 and the less intensive atmosphere of a noninvasive unit may be less distressing, although there is no evidence to support this assertion. Factors to be considered include whether or not intubation is felt to be appropriate should NPPV fail, the presence of other system failure, comorbidity, the severity of the respiratory failure and the likelihood of success with NPPV. Nurses, physiotherapists or respiratory therapists may be the primary-care giver and this will depend upon local availability, enthusiasm and expertize. Patients who cannot sustain ventilation for more than a minute or two when acutely unwell require continuous observation. Patients with this severity of ventilatory failure are often confused and usually require high inflation pressures. Continuous observation is needed to ensure that the patient does not remove the mask and that leaks are minimized. Even if the patient does not remove the mask there is a tendency for the Velcro straps of the head gear to gradually work loose with high pressures and for mask leaks to develop.

The best location for a NPPV service will depend critically upon local factors, particularly the skill levels of doctors, nurses and therapists in looking after patients receiving NPPV. Severely ill patients, who do not need NPPV, may benefit from the extra monitoring and nurse staffing available in a higher-dependency setting.

Monitoring

The monitoring required during NPPV is summarized in table 2. There are no RCTs which address the issue of whether monitoring improves outcome. Monitoring serves two roles; firstly safety to warn of impending catastrophe and secondly optimization of ventilator settings. Vitacca et al. 29 have shown that setting a ventilator on the basis of physiologically derived information results in more complete respiratory-muscle unloading than when the ventilator was set, by experienced operators, using clinical judgement alone. The evaluation of patient-ventilator asynchrony is difficult without visualization of flow and pressure waveforms 20. Ely et al. 30 showed that patients could be weaned from assisted ventilation more rapidly when the results of physiological measurements were made available to medical staff. Even for experienced practitioners decisions based on physiological measurements are superior to clinical judgement in setting the ventilator and deciding the appropriate management strategy. Further work is needed to establish which parameters should be monitored to optimize NPPV. It should be remembered however that high technology monitoring is never a substitute for good clinical observation 31.

Implications for staffing and training

Training requirements for NPPV are summarized in table 3. NPPV has been reported to be a time consuming procedure 42 but as with any new technique there is a learning curve and the same group have subsequently published more encouraging results 43. A number of studies in the ICU, have shown that to start with a significant amount of time is required to establish the patient on NPPV, but this drops off substantially in subsequent days 3, 44, 45. It is possible therefore that NPPV may have a much greater impact on nursing workload outside the ICU, where nurses have responsibility for a larger number of patients. In the study of Bott et al. 1 there was no difference in nursing workload, assessed by asking the senior nurse to rate, on a visual analogue scale, the amount of care needed in the conventional and NPPV groups. However, this is an insensitive way of measuring nursing needs and in addition some of the potential extra work associated with NPPV was performed by supernumerary research staff. In the study of Plant et al. 10, NPPV resulted in a modest increase in nursing workload, assessed using an end-of-bed log, in the first 8 h of the admission, equating to 26 min, but no difference was identified thereafter. However, there is no data on the effect of NPPV on the care that other patients on the ward received nor whether the outcome would have been better if the nurses had spent more time with the patients receiving NPPV. In other words although this study showed that NPPV was feasible in the general ward environment it does not mean that it was the optimal situation. Furthermore, even if good results can be obtained it may be at the expense of the care of other patients. Most of the centres that participated in the study had little or no previous experience of NPPV and therefore required training in mask fitting and application of NPPV. The mean amount of formal training given in the first 3 months of opening a ward by the research doctor and nurse was 7.6 h (sd 3.6). Thereafter each centre received 0.9 h·month^–1 (sd 0.82) to maintain the skills. It should be appreciated that there was no need to make subtle adjustments to the ventilator settings which were all done according to protocol. Much more training would be needed if more sophisticated ventilators were used. However, it underlines the fact that NPPV, in whatever location, is not just a question of purchasing the necessary equipment but also of staff training. Although a considerable amount of input is likely when a unit first starts to provide a NPPV service thereafter, as long as a critical mass of nurses and therapists remain, new staff will gain the necessary skills from their colleagues. In view of the fact that NPPV in the more severely-ill patient may require as much input as an invasively ventilated patient 44 there should usually be one nurse responsible for no more than three or four patients, though clearly this will be depend upon the care needs of the other patients. In the less severely affected patient NPPV can be successful with a lower level of staffing 10.

Economic analysis in medicine is complex and as a result many diagnostic and therapeutic technologies have been adopted into practice without any consideration of the economic implications. Even techniques with a clear clinical advantage may not be endorsed in the current healthcare climate without a favourable cost-effectiveness analysis. The first step in an economic analysis is to calculate the cost of an intervention. Relevant costs for ventilation include equipment, supplies, capital and overheads. More complex, is the calculation of the costs for the care of patients, including medical and paramedical time and the level of assistance, laboratory and pharmacy costs, nutrition and ventilation costs. The daily cost of NPPV has been reported to be similar to that of standard medical therapy 3 or invasive ventilation (calculated only on the first day of treatment) 44. According to the different studies and countries, the mean daily cost of NPPV varies from US$850 44 to US$1500 3, 46; the difference is mainly due to the salaries of the personnel, which are much higher in the USA than in Europe. The second step is to evaluate the outcome for the patients. The outcomes may be calculated in terms of economic resources saved or created, efficacy of the treatment in improving survival, or in the case of NPPV the rate of intubation, or as the impact of a technique to ameliorate quality of life.

Though the findings are not consistent it has been shown in some of the larger studies that NPPV can shorten the length of ICU and/or hospital stay, compared for example with medical therapy or invasive ventilation 2, 3, 7, 11, 15, 16. In no study has NPPV been shown to lengthen the duration of hospital stay. Although not the primary aim of the studies the finding of a reduced hospital, and particularly ICU length of stay, creates or saves resources and thereby indicates a cost benefit from NPPV.

Cost-effectiveness is the most "popular" way to perform an economic analysis. To date there is only one study analysing this in detail, in patients with an acute exacerbation of COPD, using base care modelled for a tertiary care teaching hospital 47. The two alternatives considered were NPPV and standard medical therapy, while the main outcomes modelled and calculated were costs, mortality and intubation rates. To determine clinical effectiveness Keenan et al. 47 used a meta-analysis of randomized trials. Then a decision tree was constructed and probabilities were applied at each chance node using research evidence and a comprehensive regional database. Keenan et al. 47 concluded that NPPV was more effective than standard treatment in reducing hospital mortality and at the same time less expensive, with a cost saving of about US$2,500 per patient admission. The major problem with this kind of analysis is that the clinical data come from different studies, not all with a well-defined selection of patients, so that applicability to a large population is not possible. Furthermore the different models and costs of healthcare in different countries, and indeed between different institutions within the same country, make comparisons very difficult.

Another factor that may have a major impact on economic analysis is the location in which NPPV is performed. The opening of intermediate respiratory units, providing for example, noninvasive monitoring and NPPV, and not needing major expenditure on building a dedicated area with a better nurse/patient ratio than the general ward and some basic monitoring (i.e. electrocardiogram and arterial oxygen saturation), may be an excellent alternative to the "classical" ICU 26. It has been shown that the daily costs of a ventilated patient may be reduced by two-thirds, when NPPV is performed in a specialized respiratory unit, rather than in an ICU 27. These costs can be reduced still further when NPPV is performed on a general ward, though effectiveness may not be so good primarily because of fewer nurses to deliver care to an individual patient.

Despite the possible money savings, the system of payment is a major problem. If the reimbursments are made through the diagnosis-related group (DRG) system, the daily loss per patient is $350 46. In countries where reimbursement is made on the basis of DRGs there is an urgent need to provide adequate reimbursement for NPPV. If this is not done clinicians may be compelled, by their managers, to intubate patients because this attracts more realistic reimbursement. This is to the detriment of patients, because of the worse outcomes when NPPV is not used, and at a greater cost to payers.

Conclusion

Staff training and experience is more important than location, and adequate numbers of staff skilled in noninvasive positive-pressure ventilation must be available throughout the 24-h period. Because of the demands of looking after these acutely-ill patients, and to aid training and skill retention, noninvasive positive-pressure ventilation is usually best carried out in one single sex location with one nurse responsible for no more than three to four patients in total. Basic monitoring should be available. Whether this is called an intensive care unit, a high dependency unit or is part of a general ward is largely irrelevant. Available data suggests that noninvasive positive-pressure ventilation for acute and chronic respiratory failure is a cost- effective intervention.

Footnotes

Previous articles in this series: No. 1: Brochard L, Mancebo J, Elliott MW. Noninvasive ventilation for acute respiratory failure. Eur Respir J 2002; 19: 712–721. No. 2: Ferrer M, Bernadich O, Nava S, Torres A. Noinvasive ventilation after intubation and mechanical ventilation. Eur Respir J 2002; 19: 959–965.

References

1. Bott J, Carroll MP, Conway JH, et al. Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease. Lancet 1993;341:1555–1557.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
2. Brochard L, Mancebo J, Wysocki M, et al. Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonay disease. N Engl J Med 1995;333:817–822.[Abstract/Free Full Text]
3. Kramer N, Meyer TJ, Meharg J, Cece RD, Hill NS. Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med 1995;151:1799–1806.[Abstract]
4. Barbe F, Togores B, Rubi M, Pons S, Maimo A, Agusti AGN. Noninvasive ventilatory support does not facilitate recovery from acute respiratory failure in chronic obstructive pulmonary disease. Eur Respir J 1996;9:1240–1245.[Abstract]
5. Angus RM, Ahmed AA, Fenwick LJ, Peacock AJ. Comparison of the acute effects on gas exchange of nasal ventilation and doxapram in exacerbations of chronic obstructive pulmonary disease. Thorax 1996;51:1048–1050.[Abstract/Free Full Text]
6. Wood KA, Lewis L, Von Harz B, Kollef MH. The use of noninvasive positive pressure ventilation in the Emergency Department. Chest 1998;113:1339–1346.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
7. Celikel T, Sungur M, Ceyhan B, Karakurt S. Comparison of noninvasive positive pressure ventilation with standard medical therapy in hypercapnic acute respiratory failure. Chest 1998;114:1636–1642.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
8. Bardi G, Pierotello R, Desideri M, Valdisseri L, Bottai M, Palla A. Nasal ventilation in COPD exacerbations: early and late results of a prospective, controlled study. Eur Respir J 2000;15:98–104.[Abstract]
9. Martin TJ, Hovis JD, Costantino JP, et al. A randomized, prospective evaluation of noninvasive ventilation for acute respiratory failure. Am J Respir Crit Care Med 2000;161:807–813.[Abstract/Free Full Text]
10. Plant PK, Owen JL, Elliott MW. Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: a multicentre randomised controlled trial. Lancet 2000;355:1931–1935.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
11. Antonelli M, Conti G, Rocco M, et al. A comparison of noninvasive positive-pressure ventilation and conventional mechanical ventilation in patients with acute respiratory failure. N Engl J Med 1998;339:429–435.[Abstract/Free Full Text]
12. Confalonieri M, Potena A, Carbone G, Porta RD, Tolley EA, Meduri UG. Acute respiratory failure in patients with severe community-acquired pneumonia. A prospective randomized evaluation of noninvasive ventilation. Am J Respir Crit Care Med 1999;160:1585–1591.[Abstract/Free Full Text]
13. Mehta S, Jay GD, Woolard RH, et al. Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary oedema. Crit Care Med 1997;25:620–628.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
14. Masip J, Betbese AJ, Paez J, et al. Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardiogenic pulmonary oedema: a randomised trial. Lancet 2000;356:2126–2132.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
15. Antonelli M, Conti G, Bufi M, et al. Noninvasive ventilation for treatment of acute respiratory failure in patients undergoing solid organ transplantation: a randomized trial. JAMA 2000;283:235–241.[Abstract/Free Full Text]
16. Hilbert G, Gruson D, Vargas F, et al. Noninvasive ventilation in immunosuppressed patients with pulmonary infiltrates, fever, and acute respiratory failure. N Engl J Med 2001;344:481–487.[Abstract/Free Full Text]
17. 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. A randomized, controlled trial. Ann Intern Med 1998;128:721–728.[Abstract/Free Full Text]
18. Girault C, Daudenthun I, Chevron V, Tamion F, Leroy J, Bonmarchand G. Noninvasive ventilation as a systematic extubation and weaning technique in acute-on-chronic respiratory failure. A prospective, randomized controlled study. Am J Respir Crit Care Med 1999;160:86–92.[Abstract/Free Full Text]
19. Anonymous. Intensive care in the United Kingdom: report from the King's Fund panel. Anaesthesia 1989;44:428–431.[Web of Science][Medline] [Order article via Infotrieve]
20. Kacmarek RM. NIPPV: patient-ventilator synchrony, the difference between success and failure? Intensive Care Med 1999;25:645–647.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
21. Calderini E, Confalonieri M, Puccio PG, Francavilla N, Stella L, Gregoretti C. Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger. Intensive Care Med 1999;25:662–667.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
22. Lofaso F, Fodil R, Lorino H, et al. Inaccuracy of tidal volume delivered by home mechanical ventilators. Eur Respir J 2000;15:338–341.[Abstract]
23. Easton C, MacKenzie F. Sensory-perceptual alterations: delirium in the intensive care unit. Heart Lung 1988;17:229–237.[Web of Science][Medline] [Order article via Infotrieve]
24. Plant PK, Owen J, Elliott MW. One year period prevalance study of respiratory acidosis in acute exacerbation of COPD; implications for the provision of non-invasive ventilation and oxygen administration. Thorax 2000;55:550–554.[Abstract/Free Full Text]
25. Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive pressure airway support on mortality and the need for intubation in cardiogenic pulmonary edema: a systematic review. Chest 1998;114:1185–1192.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
26. Nava S, Confalonieri M, Rampulla C. Intermediate respiratory intensive care units in Europe: a European perspective. Thorax 1998;53:798–802.[Free Full Text]
27. Elpern EH, Silver MR, Rosen RL, Bone RC. The noninvasive respiratory care unit. Patterns of use and financial implications. Chest 1991;99:205–208.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
28. Confalonieri M, Gorini M, Ambrosino N, Mollica C, Corrado A. Respiratory intensive care units in Italy: a national census and prospective cohort study. Thorax 2001;56:373–378.[Abstract/Free Full Text]
29. Vitacca M, Nava S, Confalonieri M, et al. The appropriate setting of noninvasive pressure support ventilation in stable COPD patients. Chest 2000;118:1286–1293.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
30. Ely EW, Baker AM, Dunagan DP, et al. Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously. N Engl J Med 1996;335:1864–1869.[Abstract/Free Full Text]
31. Tobin MJ. Respiratory monitoring. JAMA 1990;264:244–251.[Abstract/Free Full Text]
32. Jubran A, Tobin MJ. Reliability of pulse oximetry in titrating supplemental oxygen therapy in ventilator-dependent patients. Chest 1990;97:1420–1425.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
33. Stradling JR. Hypercapnia during oxygen therapy in airways obstruction: a reappraisal. Thorax 1986;41:897–902.[Free Full Text]
34. Ambrosino N, Foglio K, Rubini F, Clini E, Nava S, Vitacca M. Non-invasive mechanical ventilation in acute respiratory failure due to chronic obstructive airways disease: correlates for success. Thorax 1995;50:755–757.[Abstract/Free Full Text]
35. Meduri GU, Abou-Shala N, Fox RC, Jones CB, Leeper KV, Wunderink RG. Noninvasive face mask mechanical ventilation in patients with acute hypercapneic respiratory failure. Chest 1991;100:445–454.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
36. Soo Hoo GW, Santiago S, Williams AJ. Nasal mechanical ventilation for hypercapnic respiratory failure in chronic obstructive pulmonary disease: determinants of success and failure. Crit Care Med 1994;22:1253–1261.[Web of Science][Medline] [Order article via Infotrieve]
37. Meduri GU, Turner RE, Abou-Shala N, Wunderink R, Tolley E. Noninvasive positive pressure ventilation via face mask. First line intervention in patients with acute hypercapnic and hypoxemic respiratory failure. Chest 1996;109:179–193.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
38. Poponick JM, Renston JP, Bennett RP, Emerman CL. Use of a ventilatory support system (BiPAP) for acute respiratory failure in the emergency department. Chest 1999;116:166–171.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
39. Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med 1991;324:1445–1450.[Abstract]
40. Anton A, Guell R, Gomez J, et al. Predicting the result of noninvasive ventilation in severe acute exacerbations of patients with chronic airflow limitation. Chest 2000;117:828–833.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
41. Plant PK, Owen JL, Elliott MW. Non-invasive ventilation in acute exacerbations of chronic obstructive pulmonary disease: long term survival and predictors of in-hospital outcome. Thorax 2001;56:708–712.[Abstract/Free Full Text]
42. Chevrolet JC, Jolliet P, Abajo B, Toussi A, Louis M. Nasal positive pressure ventilation in patients with acute respiratory failure. Chest 1991;100:775–782.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
43. Chevrolet JC, Jolliet P. Workload on non-invasive ventilation in acute respiratory failure In: Vincent JL, ed. Year book of intensive and emergency medicineBerlin. Springer, 1997; pp. 505–513.
44. Nava S, Evangelisti I, Rampulla C, Compagnoni ML, Fracchia C, Rubini F. Human and financial costs of noninvasive mechanical ventilation in patients affected by COPD and acute respiratory failure. Chest 1997;111:1631–1638.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
45. Hilbert G, Gruson D, Vargas F, et al. Noninvasive ventilation for acute respiratory failure. Quite low time consumption for nurses. Eur Respir J 2000;16:710–716.[Abstract]
46. Criner GJ, Kreimer DT, Tomaselli M, Pierson W, Evans D. Financial implications of noninvasive positive pressure ventilation (NPPV). Chest 1995;108:475–481.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
47. Keenan SP, Gregor J, Sibbald WJ, Cook DJ. Gafni A. Noninvasive positive pressure ventilation in the setting of severe, acute exacerbations of chronic obstructive pulmonary disease: More effective and less expensive. Crit Care Med 2000;28:2094–2102.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]

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