Predictors of failure of noninvasive positive pressure ventilation in patients with acute hypoxemic respiratory failure: a multi-center study

Predictors of noninvasive ventilation failure in patients with hematologic malignancy and acute respiratory failure

OBJECTIVES

The current trend to manage critically ill hematologic patients admitted with acute respiratory failure is to perform noninvasive ventilation to avoid endotracheal intubation. However, failure of noninvasive ventilation may lead to an increased mortality.

DESIGN

Retrospective study to determine the frequency of noninvasive ventilation failure and identify its determinants.

SETTING

Medical intensive care unit in a University hospital.

PATIENTS

All consecutive patients with hematologic malignancies admitted to the intensive care unit over a 10-yr period who received noninvasive ventilation.

RESULTS

A total of 99 patients were studied. Simplified Acute Physiology Score II at admission was 49 (median, interquartile range, 39-57). Fifty-three patients (54%) failed noninvasive ventilation and required endotracheal intubation. Their PaO2/FiO2 ratio was significantly lower (175 [101-236] vs. 248 [134-337]) and their respiratory rate under noninvasive ventilation was significantly higher (32 breaths/min [30-36] vs. 28 [27-30]). Forty-seven patients (89%) who failed noninvasive ventilation required vasopressors. Hospital mortality was 79% in those who failed noninvasive ventilation, and 41% in those who succeeded. Patients who failed noninvasive ventilation had a significantly longer intensive care unit stay (13 days [8-23] vs. 5 [2-8]) and a significantly higher rate of intensive care unit-acquired infections (32% compared with 7%). Factors independently associated with noninvasive ventilation failure by multivariate analysis were respiratory rate under noninvasive ventilation, longer delay between admission and noninvasive ventilation first use, need for vasopressors or renal replacement therapy, and acute respiratory distress syndrome.

CONCLUSIONS

Failure of noninvasive ventilation occurs in half the critically ill hematologic patients and is associated with an increased mortality. Predictors of noninvasive ventilation failure might be used to guide decisions regarding intubation.

Noninvasive ventilation for acute respiratory failure after lung resection: an observational study

BACKGROUND

A single prospective randomized study found that, in selected patients with acute respiratory failure (ARF) following lung resection, noninvasive ventilation (NIV) decreases the need for endotracheal mechanical ventilation and improves clinical outcome.

METHOD

We prospectively evaluated early NIV use for ARF after lung resection during a 4-year period in the setting of a medical and a surgical ICU of a university hospital. We documented demographics, initial clinical characteristics and clinical outcomes. NIV failure was defined as the need for tracheal intubation.

RESULTS

Among 690 patients at risk of severe complications following lung resection, 113 (16.3%) experienced ARF, which was initially supported by NIV in 89 (78.7%), including 59 with hypoxemic ARF (66.3%) and 30 with hypercapnic ARF (33.7%). The overall success rate of NIV was 85.3% (76/89). In-ICU mortality was 6.7% (6/89). The mortality rate following NIV failure was 46.1%. Predictive factors of NIV failure in univariate analysis were age (P = 0.046), previous cardiac comorbidities (P = 0.0075), postoperative pneumonia (P = 0.0016), admission in the surgical ICU (P = 0.034), no initial response to NIV (P < 0.0001) and occurrence of noninfectious complications (P = 0.037). Only two independent factors were significantly associated with NIV failure in multivariate analysis: cardiac comorbidities (odds ratio, 11.5; 95% confidence interval, 1.9-68.3; P = 0.007) and no initial response to NIV (odds ratio, 117.6; 95% confidence interval, 10.6-1305.8; P = 0.0001).

CONCLUSION

This prospective survey confirms the feasibility and efficacy of NIV in ARF following lung resection.

Factors predicting successful noninvasive ventilation in acute lung injury

PURPOSE

Noninvasive ventilation (NIV) has been successfully used to treat various forms of acute respiratory failure. It remains unclear whether NIV has potential as an effective therapeutic method in patients with acute lung injury (ALI). The aims of this study were to determine factors predicting the need for endotracheal intubation in ALI patients treated with NIV, and to promote the selection of patients suitable for NIV.

METHODS

We conducted a retrospective study of all patients admitted to the intensive care unit (ICU) of the Nippon Medical School Hospital from 2000 to 2006 with a diagnosis of ALI, in whom NIV was initiated.

RESULTS

A total of 47 patients with ALI received NIV, and 33 patients (70%) successfully avoided endotracheal intubation. Patients who required endotracheal intubation had a significantly higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and a significantly higher Simplified Acute Physiology Score (SAPS) II, and a significantly lower arterial pH. The respiratory rate decreased significantly within 1 h of starting NIV only in patients successfully treated with NIV. An APACHE II score of more than 17 (P = 0.022) and a respiratory rate of more than 25 breaths x min(-1) after 1 h of NIV (P = 0.024) were independent factors associated with the need for endotracheal intubation. Patients who avoided endotracheal intubation had a significantly lower ICU mortality rate and in-hospital mortality rate than patients who required endotracheal intubation.

CONCLUSION

We determined an APACHE II score of more than 17 and a respiratory rate of more than 25 breaths x min(-1) after 1 h of NIV as factors predicting the need for endotracheal intubation in ALI patients treated with NIV.

Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary edema

BACKGROUND

Non-invasive positive pressure ventilation (NPPV) has been widely used to alleviate signs and symptoms of respiratory distress due to cardiogenic pulmonary edema. NPPV prevents alveolar collapse and helps redistribute intra-alveolar fluid, improving pulmonary compliance and reducing the pressure of breathing.

OBJECTIVES

To determine the effectiveness and safety of NPPV in the treatment of adult patients with cardiogenic pulmonary edema.

SEARCH STRATEGY

We undertook a comprehensive search of the following databases in April 2005: CENTRAL, MEDLINE, EMBASE, CINAHL, DARE and LILACS. We also reviewed reference lists of included studies and contacted experts, equipment manufacturers, and the Cochrane Heart Group. We did not apply language restrictions.

SELECTION CRITERIA

We selected blinded or unblinded randomized or quasi-randomized clinical trials, reporting on adult patients with acute or acute-on-chronic cardiogenic pulmonary edema and where NPPV (continuous positive airway pressure (CPAP)) and/or bilevel NPPV plus standard medical care was compared with standard medical care alone.

DATA COLLECTION AND ANALYSIS

Two authors independently selected articles and abstracted data using a standardized data collection form. We evaluated study quality with emphasis on allocation concealment, adherence to the intention-to-treat principle and losses to follow-up.

MAIN RESULTS

We included 21 studies involving 1,071 participants. Compared to standard medical care, NPPV significantly reduced hospital mortality (RR 0.6, 95% CI 0.45 to 0.84) and endotracheal intubation (RR 0.53, 95% CI 0.34 to 0.83) with numbers needed to treat of 13 and 8, respectively. We found no difference in hospital length of stay with NPPV, however, intensive care unit stay was reduced by 1 day (WMD -1.07 days, 95% CI -1.60 to -0.53). Compared to standard medical care, we did not observe significant increases in the incidence of acute myocardial infarction with NPPV during (RR 1.24, 95% CI 0.79 to 1.95) or after (RR 0.82, 95% CI 0.09 to 7.54) its application.

AUTHORS' CONCLUSIONS

NPPV, especially CPAP, in addition to standard medical care is an effective and safe intervention for the treatment of adult patients with acute cardiogenic pulmonary edema.

Clinical practice guideline: non-invasive mechanical ventilation as treatment of acute respiratory failure

INTRODUCTION

Non-invasive mechanical ventilation (NIV) has been used to treat acute respiratory failure (ARF) for approximately 20 years. This guideline addresses the indications for, and limitations of, NIV as treatment for ARF according to evidence-based criteria.

METHODS

A panel of experts from 12 scientific medical societies reviewed circa 2900 publications. The panel judged the clinical relevance of these studies and assessed the evidence presented in each, then held two interdisciplinary consensus conferences to formulate guideline recommendations and algorithms.

RESULTS

Whenever possible, NIV should be preferred to invasive mechanical ventilation, in order to avoid the risk of ventilator and tube-associated complications such as nosocomial pneumonia (grade of recommendation A). Particularly in patients with hypercapnic ARF, NIV reduces the rate of hospital-acquired pneumonia, the length of hospital stay and mortality in the intensive care unit and in the hospital (grade of recommendation A). NIV (or continuous positive airway pressure) is also recommended in cardiogenic pulmonary edema (grade of recommendation A), as treatment for ARF in immunocompromised patients (grade of recommendation A), to prevent postextubation failure, to facilitate weaning in patients with hypercapnic ARF (grade of recommendation A), and to improve dyspnea in palliative care (grade of recommendation C). NIV is not generally recommended in patients with hypoxic ARF because of its high failure rate of 30% to over 50% in such patients.

DISCUSSION

Although evidence indicates that NIV can be used as the treatment of first choice for several indications, it is still underutilized in the acute setting. These guidelines provide evidence-based information about the indications for, and limitations of, NIV in the treatment of ARF.

Edema e hemorragia pulmonar por pressão negativa associados à obstrução das vias aéreas superiores

O edema pulmonar por pressão negativa associado à hemorragia como manifestação de obstrução das vias aéreas superiores é um problema incomum com potencial risco de morte. O principal mecanismo fisiopatológico envolvido é a geração de uma acentuada pressão negativa intratorácica que eleva tanto o volume vascular como a pressão transmural capilar pulmonar, causando risco de ruptura da membrana alvéolo-capilar. Relatamos o caso de um paciente do sexo masculino com hemorragia alveolar difusa após obstrução aguda das vias aéreas superiores causada pela formação de um abscesso cervical e mediastinal decorrente do implante de uma órtese traqueal metálica. O paciente foi tratado com drenagem do abscesso, antibioticoterapia e ventilação mecânica com pressão positiva. Este artigo enfatiza a importância de incluir essa entidade no diagnóstico diferencial da lesão pulmonar aguda após procedimentos que envolvam a manipulação das vias aéreas superiores.

Noninvasive positive-pressure ventilation in acute respiratory failure outside clinical trials: experience at the Massachusetts General Hospital

BACKGROUND

Noninvasive positive-pressure ventilation (NPPV) has been shown to be effective in select patients enrolled in clinical trials. However, few data are available on the use of NPPV as routine standard medical care for patients with respiratory failure outside of controlled trials.

MEASUREMENTS AND MAIN RESULTS

All patients receiving NPPV for a 1-yr period for acute or acute on chronic respiratory failure who did not select do not intubate/resuscitate status were evaluated. Demographic, physiological, and laboratory data were collected for as long as NPPV was provided. Data were recorded on 449 patients. Intubation rate was 18%, 24%, 38%, 40%, and 60%, respectively, for patients with cardiogenic pulmonary edema (n = 97), acute exacerbation of chronic obstructive pulmonary disease (n = 87), non-chronic obstructive pulmonary disease acute hypercapnic respiratory failure (n = 35), postextubation respiratory failure patients (n = 95), and acute hypoxemic respiratory failure (n = 144). The hospital mortality for patients with acute hypoxemic respiratory failure who failed NPPV was 64%. A logistic regression showed that baseline Simplified Acute Physiology Score II (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.05-1.10; p <.0001), Glasgow Coma Scale (OR, 0.76; 95% CI, 0.66-0.87; p <.0001), PaO2/FIO2 ratio (OR, 0.98; 95% CI, 0.93-0.99; p = .02), and serum albumin (OR, 0.30; 95% CI, 0.16-0.57; p < .001) were the variables associated with NPPV failure.

CONCLUSION

NPPV as routine standard medical care resulted in the intubation of a similar percentage of patients with respiratory failure due to cardiogenic pulmonary edema and chronic obstructive pulmonary disease exacerbation as shown in randomized controlled trials but in a higher percent of patients with hypoxemic respiratory failure than reported in these trials. NPPV failure was associated with high hospital mortality for patients with hypoxemic respiratory failure.

Noninvasive positive pressure ventilation in acute respiratory failure due to COPD vs other causes: effectiveness and predictors of failure in a respiratory ICU in North India

OBJECTIVES

To determine the effectiveness of noninvasive positive pressure ventilation (NIPPV), and the factors predicting failure of NIPPV in acute respiratory failure (ARF) due to chronic obstructive pulmonary disease (COPD) versus other causes of ARF.

PATIENTS AND METHODS

This was a prospective observational study and all patients with ARF requiring NIPPV over a one-and-a-half year period were enrolled in the study. We recorded the etiology of ARF and prospectively collected the data for heart rate, respiratory rate, arterial blood gases (pH, partial pressure of oxygen in the arterial blood [PaO2], partial pressure of carbon dioxide in arterial blood [PaCO2]) at baseline, one and four hours. The patients were further classified into two groups based on the etiology of ARF as COPD-ARF and ARF due to other causes. The primary outcome was the need for endotracheal intubation during the intensive care unit (ICU) stay.

RESULTS

During the study period, 248 patients were admitted in the ICU and of these 63 (25.4%; 24, COPD-ARF, 39, ARF due to other causes; 40 male and 23 female patients; mean [standard deviation] age of 45.7 [16.6] years) patients were initiated on NIPPV. Patients with ARF secondary to COPD were older, had higher APACHE II scores, lower respiratory rates, lower pH and higher PaCO2 levels compared to other causes of ARF. After one hour there was a significant decrease in respiratory rate and heart rate and decline in PaCO2 levels with increase in pH and PaO2 levels in patients successfully managed with NIPPV. However, there was no difference in improvement of clinical and blood gas parameters between the two groups except the rate of decline of pH at one and four hours and PaCO2 at one hour which was significantly faster in the COPD group. NIPPV failures were significantly higher in ARF due to other causes (15/39) than in ARF-COPD (3/24) (p = 0.03). The mean ICU and hospital stay and the hospital mortality were similar in the two groups. In the multivariate logistic regression model (after adjusting for gender, APACHE II scores and improvement in respiratory rate, pH, PaO2 and PaCO2 at one hour) only the etiology of ARF, ie, ARF-COPD, was associated with a decreased risk of NIPPV failure (odds ratio 0.23; 95% confidence interval, 0.58-0.9).

CONCLUSIONS

NIPPV is more effective in preventing endotracheal intubation in ARF due to COPD than other causes, and the etiology of ARF is an important predictor of NIPPV failure.

Noninvasive ventilation in acute respiratory failure

BACKGROUND

Noninvasive ventilation has assumed an important role in the management of respiratory failure in critical care units, but it must be used selectively depending on the patient's diagnosis and clinical characteristics.

DATA

We review the strong evidence supporting the use of noninvasive ventilation for acute respiratory failure to prevent intubation in patients with chronic obstructive pulmonary disease exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with chronic obstructive pulmonary disease who require initial intubation. Weaker evidence supports consideration of noninvasive ventilation for chronic obstructive pulmonary disease patients with postoperative or postextubation respiratory failure; patients with acute respiratory failure due to asthma exacerbations, pneumonia, acute lung injury, or acute respiratory distress syndrome; during bronchoscopy; or as a means of preoxygenation before intubation in critically ill patients with severe hypoxemia.

CONCLUSION

Noninvasive ventilation has assumed an important role in managing patients with acute respiratory failure. Patients should be monitored closely for signs of noninvasive ventilation failure and promptly intubated before a crisis develops. The application of noninvasive ventilation by a trained and experienced intensive care unit team, with careful patient selection, should optimize patient outcomes.

Noninvasive ventilation for critical care

Noninvasive ventilation (NIV), the provision of ventilatory assistance without an artificial airway, has emerged as an important ventilatory modality in critical care. This has been fueled by evidence demonstrating improved outcomes in patients with respiratory failure due to COPD exacerbations, acute cardiogenic pulmonary edema, or immunocompromised states, and when NIV is used to facilitate extubation in COPD patients with failed spontaneous breathing trials. Numerous other applications are supported by weaker evidence. A trial of NIV is justified in patients with acute respiratory failure due to asthma exacerbations and postoperative states, extubation failure, hypoxemic respiratory failure, or a do-not-intubate status. Patients must be carefully selected according to available guidelines and clinical judgment, taking into account risk factors for NIV failure. Patients begun on NIV should be monitored closely in an ICU or other suitable setting until adequately stabilized, paying attention not only to vital signs and gas exchange, but also to comfort and tolerance. Patients not having a favorable initial response to NIV should be considered for intubation without delay. NIV is currently used in only a select minority of patients with acute respiratory failure, but with technical advances and new evidence on its proper application, this role is likely to further expand.

Noninvasive ventilation in patients with hypoxemic acute respiratory failure

PURPOSE OF REVIEW

To discuss the recent literature concerning the use of noninvasive ventilation for hypoxemic acute respiratory failure.

RECENT FINDINGS

The benefits of noninvasive ventilation for patients with hypoxemic acute respiratory failure are unclear. In immunocompromised patients and following thoracic surgery, there is a strong rationale for using noninvasive ventilation to treat acute respiratory failure. Prophylactic continuous positive airway pressure after abdominal or thoracic surgery and prophylactic noninvasive ventilation in patients at risk of extubation failure have proved beneficial. Recent studies show that noninvasive ventilation has a favourable impact in immunocompetent patients with acute lung injury/acute respiratory distress syndrome, but caution is required. In hypoxemic acute respiratory failure after extubation, one study reported excess mortality in patients treated with noninvasive ventilation, possibly related to the delay for intubation. A major issue is avoiding undue noninvasive ventilation prolongation and staying alert for predictors of early noninvasive ventilation failure. Caution, close monitoring, and broad experience are required.

SUMMARY

Hypoxemic acute respiratory failure may benefit from noninvasive ventilation or continuous positive airway pressure, but undue prolongation should be avoided. In postextubation respiratory failure there is no evidence for routine use of noninvasive ventilation.

Performance of noninvasive ventilation modes on ICU ventilators during pressure support: a bench model study

OBJECTIVE

Noninvasive ventilation (NIV) is often applied with ICU ventilators. However, leaks at the patient-ventilator interface interfere with several key ventilator functions. Many ICU ventilators feature an NIV-specific mode dedicated to preventing these problems. The present bench model study aimed to evaluate the performance of these modes.

DESIGN AND SETTING

Bench model study in an intensive care research laboratory of a university hospital.

METHODS

Eight ICU ventilators, widely available in Europe and featuring an NIV mode, were connected by an NIV mask to a lung model featuring a plastic head to mimic NIV conditions, driven by an ICU ventilator imitating patient effort. Tests were conducted in the absence and presence of leaks, the latter condition with and without activation of the NIV mode. Trigger delay, trigger-associated inspiratory workload, and pressurization were tested in conditions of normal respiratory mechanics, and cycling was also assessed in obstructive and restrictive conditions.

RESULTS

On most ventilators leaks led to an increase in trigger delay and workload, a decrease in pressurization, and delayed cycling. On most ventilators the NIV mode partly or totally corrected these problems, but with large variations between machines. Furthermore, on some ventilators the NIV mode worsened the leak-induced dysfunction.

CONCLUSIONS

The results of this bench-model NIV study confirm that leaks interfere with several key functions of ICU ventilators. Overall, NIV modes can correct part or all of this interference, but with wide variations between machines in terms of efficiency. Clinicians should be aware of these differences when applying NIV with an ICU ventilator.

Automatic adjustment of noninvasive pressure support with a bilevel home ventilator in patients with acute respiratory failure: a feasibility study

OBJECTIVE

To test the feasibility of applying noninvasive ventilation (NIV) using a prototype algorithm implemented in a bilevel ventilation device designed to adjust pressure support (PS) to maintain a clinician-set alveolar ventilation in patients with acute respiratory failure after initial stabilization.

DESIGN AND SETTING

Prospective crossover interventional study in an intensive care unit, university hospital.

PATIENTS

19 patients receiving NIV for acute hypercapnic respiratory failure (13 men, 6 women; mean age 70+/-11 years).

METHODS

The same bilevel ventilator was used with manually adjusted PS and with the automated algorithm (autoPS), set to maintain the same alveolar ventilation as in PS. Sequence (measurements at end of each period): (a) prior to initiating NIV (baseline 1); (b) 45 min with manually set PS; (c) 60 min without NIV; (d) 45 min with autoPS; (e) 60 min without NIV; (f) 45 min with manually set PS.

RESULTS

The magnitude of decrease in PaCO(2) and increase in pH with autoPS was comparable to that of conventional PS, with the same alveolar ventilation and level of PS. No technical problem occurred in autoPS mode, and no NIV trial had to be discontinued because of patient discomfort.

CONCLUSIONS

These results suggest that the alveolar ventilation based automatic control of PS during NIV with a bilevel device is feasible and leads to beneficial effects in patients with acute respiratory failure comparable to those of manually set PS. Further studies should now explore the potential of this system over longer periods in patients with acute and chronic respiratory failure.

A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome

OBJECTIVE

In randomized studies of heterogeneous patients with hypoxemic acute respiratory failure, noninvasive positive pressure ventilation (NPPV) was associated with a significant reduction in endotracheal intubation. The role of NPPV in patients with acute respiratory distress syndrome (ARDS) is still unclear. The objective was to investigate the application of NPPV as a first-line intervention in patients with early ARDS, describing what happens in everyday clinical practice in centers having expertise with NPPV.

DESIGN

Prospective, multiple-center cohort study.

SETTING

Three European intensive care units having expertise with NPPV.

PATIENTS

Between March 2002 and April 2004, 479 patients with ARDS were admitted to the intensive care units. Three hundred and thirty-two ARDS patients were already intubated, so 147 were eligible for the study.

INTERVENTIONS

Application of NPPV.

MEASUREMENTS AND MAIN RESULTS

NPPV improved gas exchange and avoided intubation in 79 patients (54%). Avoidance of intubation was associated with less ventilator-associated pneumonia (2% vs. 20%; p < .001) and a lower intensive care unit mortality rate (6% vs. 53%; p < .001). Intubation was more likely in patients who were older (p = .02), had a higher Simplified Acute Physiology Score (SAPS) II (p < .001), or needed a higher level of positive end-expiratory pressure (p = .03) and pressure support ventilation (p = .02). Only SAPS II >34 and a Pao2/Fio2 < or =175 after 1 hr of NPPV were independently associated with NPPV failure and need for endotracheal intubation.

CONCLUSIONS

In expert centers, NPPV applied as first-line intervention in ARDS avoided intubation in 54% of treated patients. A SAPS II >34 and the inability to improve Pao2/Fio2 after 1 hr of NPPV were predictors of failure.

Overview of respiratory failure in older adults

Older adults comprise 48% of the critically ill population in intensive care units and will continue to represent a substantial proportion of patients requiring intensive care for decades to come. Aging both decreases the reserve capacity of vital organs and increases the risk of concurrent illnesses that challenge the respiratory system, such as pneumonia, renal failure, or heart diseases. Because respiratory failure is one of the leading causes of death in intensive care units, implementation of strategies to prevent the need for reintubation should be considered early in the course of respiratory decompensation. For those who require mechanical ventilation, protocols to identify patients who are ready to wean should facilitate liberation from respiratory support and reduce complications of mechanical ventilation. Finally, allocation of potentially limited health care resources necessitates knowing about the risk-benefit of mechanical ventilation and other treatment for respiratory failure in this population.

[Bronchial obstruction in intensive care]

Bronchial obstruction due to one of the major pulmonary diseases asthma, COPD, or emphysema are a common problem in intensive care medicine as the leading cause or as comorbidity. While in pharmacological therapy no major changes have occurred during the last few years, two major advances have been reached in ventilation therapy which are in the focus of this review. First the non invasive ventilation (NIV) has been shown to prove efficient in treating acute on chronic respiratory failure in COPD patients and is capable of shortening the duration of hospital stay. In addition NIV can be used successfully in weaning after long time ventilator therapy and improve prognosis in COPD patients. Secondly the strategy of invasive ventilation therapy has changed significantly. "Permissive hypercapnia" is unequivocally established in severe bronchial obstruction in situations of limited ventilation. When intrinsic PEEP and elevated airway resistance are present PEEP may be useful and the upper limit of airways peak pressure that we are used to in "protective ventilation" of ARDS patients can be necessary and useful to exceed.

Danger of helmet continuous positive airway pressure during failure of fresh gas source supply

OBJECTIVE

To assess the behavior of different helmets after discontinuation of fresh gas flow by disconnection at the helmet inlet, flow generator, or gas source.

DESIGN AND SETTING

Randomized physiological study in a university research laboratory.

PATIENTS

Five healthy volunteers.

INTERVENTION

CPAP (FIO2 50%, PEEP 5 cmH2O) delivered in random sequence with three different helmets: 4Vent (Rüsch), PN500 (Harol), CaStar (StarMed) with antisuffocation valve open or locked. For each helmet all three disconnections were randomly employed up to 4 min.

MEASUREMENTS AND RESULTS

During flow disconnection we measured: respiratory rate and tidal volume by respitrace; inspiratory and expiratory CO2 concentration, and FIO2 from a nostril; SpO2 by pulse oxymetry. Independently of the site of disconnection we observed a fast increase in CO2 rebreathing and minute ventilation, associated with a decrease in inspired O2 concentration. In the absence of an operational safety valve, larger helmet size and lower resistance of the inlet hose resulted in slower increase in CO2 rebreathing. The presence of the safety valve limited the rebreathing of CO2, and the increase in minute ventilation but did not protect from a decrease in FIO2 and loss of PEEP.

CONCLUSIONS

While the use of a safety valve proved effective in limiting CO2 rebreathing, it did not protect from the risk of hypoxia related to decrease in FIO2 and loss of PEEP. In addition to a safety antisuffocation valve, a dedicated monitoring and alarming systems are needed to employ helmet CPAP safely.

Noninvasive ventilation for acute lung injury: how often should we try, how often should we fail?

The selection of patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) to receive noninvasive ventilation (NIV) is challenging, partly because there are few reliable selection criteria. The study by Rana and colleagues in the previous issue of Critical Care identifies metabolic acidosis and a lower oxygenation index as predictors of NIV failure, although it is unable to identify threshold values. It also demonstrates that treating patients with NIV for ALI/ARDS and shock is an exercise in futility. Future studies need to focus on criteria that will enable selection of patients for whom NIV will have a high likelihood of success.

Benefits and risks of success or failure of noninvasive ventilation

OBJECTIVE

Noninvasive ventilation (NIV) fails more frequently for de novo acute respiratory failure (de novo) than for cardiogenic pulmonary edema (CPE) or acute-on-chronic respiratory failure (AOC). The impact of NIV failure and success was compared between de novo and CPE or AOC after adjustment for disease severity.

SETTINGS

Patients requiring ventilatory support were enrolled in a prospective survey in 70 French ICUs. Of 1076 patients requiring ventilatory support, 524 were eligible, including 299 de novo (NIV use, 30%) and 225 CPE-AOC (NIV use, 55%).

DESIGN AND ANALYSIS

Independent risk factors associated with mortality and length of stay were identified by logistic regression analysis. The adjusted outcome of NIV success or failure was compared to that with endotracheal intubation without NIV.

RESULTS

NIV success was independently associated with survival in both de novo, adjusted OR 0.05 (95% CI 0.01-0.42), and CPE-AOC OR 0.03 (CI 0.01-0.24). NIV failure was associated with ICU mortality in the de novo group (OR 3.24, CI 1.61-6.53) but not in the CPE-AOC group. Nosocomial pneumonia was less common in patients successful with NIV. NIV failure was associated with a longer ICU stay in CPE-AOC only. The overall use of NIV was independently associated with a better outcome only in CPE-AOC patients (OR 0.33, CI 0.15-0.73).

CONCLUSION

The effect of NIV differs between de novo and CPE-AOC patients because NIV failure is associated with increased mortality for de novo patients. This finding should raise a note of caution when applying NIV in this indication.

Negative-pressure pulmonary edema after resection of mediastinum thyroid goiter

Negative-pressure pulmonary edema (NPPE) is an uncommon but life-threatening complication of acute or chronic upper airway obstruction; however, there are few reports of NPPE after giant goiter resection. We report a case with severe NPPE induced by the resection of a mediastinum thyroid goiter. The patient was successfully treated by non-invasive positive airway ventilation (NPPV).

Management of acute ventilatory failure

Acute ventilatory failure is a challenging yet increasingly common medical emergency reflecting the growing burden of respiratory disease. It is not a diagnosis in itself but the end result of a diversity of disease processes culminating in arterial hypoxaemia and hypercapnia. This review focuses on key management issues including giving appropriate oxygen therapy, treatment of the underlying aetiology as well as any precipitant factors and provision of assisted ventilation if required. Ventilatory assistance can be provided both invasively and non-invasively and the indications for either or both forms of assisted ventilation are discussed. Further emphasis is needed regarding advanced directives of care and clinicians should be aware of ethical issues regarding assisted ventilation.

Automatic adjustment of pressure support by a computer-driven knowledge-based system during noninvasive ventilation: a feasibility study

OBJECTIVE

To evaluate the feasibility of using a knowledge-based system designed to automatically titrate pressure support (PS) to maintain the patient in a "respiratory comfort zone" during noninvasive ventilation (NIV) in patients with acute respiratory failure.

DESIGN AND SETTING

Prospective crossover interventional study in an intensive care unit of a university hospital.

PATIENTS

Twenty patients.

INTERVENTIONS

After initial NIV setting and startup in conventional PS by the chest physiotherapist NIV was continued for 45 min with the automated PS activated.

MEASUREMENTS AND RESULTS

During automated PS minute-volume was maintained constant while respiratory rate decreased significantly from its pre-NIV value (20+/-3 vs. 25+/-3 bpm). There was a trend towards a progressive lowering of dyspnea. In hypercapnic patients PaCO(2) decreased significantly from 61+/-9 to 51+/-2 mmHg, and pH increased significantly from 7.31+/-0.05 to 7.35+/-0.03. Automated PS was well tolerated. Two system malfunctions occurred prompting physiotherapist intervention.

CONCLUSIONS

The results of this feasibility study suggest that the system can be used during NIV in patients with acute respiratory failure. Further studies should now determine whether it can improve patient-ventilator interaction and reduce caregiver workload.

Increased use of noninvasive ventilation in French intensive care units

OBJECTIVES

A prospective survey of French intensive care units (ICUs) in 1997 showed moderate and variable use of noninvasive ventilation (NIV). This study examined changes in NIV use in French ICUs after the intervening 5years.

SETTINGS

Patients were enrolled in a prospective survey in 70 French ICUs.

METHODS

Three-week survey, with prospective inclusion of all patients requiring ventilatory support.

MEASUREMENTS AND RESULTS

Overall 1,076 patients received ventilatory support (55% of admissions). First-line NIV was significantly more common than 5years earlier, overall (23% vs. 16%) and especially in patients not intubated before ICU admission (52% vs. 35%). Reasons for respiratory failure were coma (33%), cardiogenic pulmonary edema (8%), acute-on-chronic respiratory failure (17%), and de novo respiratory failure (41%). Significant increases in NIV use were noted for acute-on-chronic respiratory failure (64% vs. 50%) and de novo respiratory failure (22% vs. 14%). Among patients given NIV, 38% subsequently required endotracheal intubation (not significantly different). Independent risk factors for NIV failure were high SAPS II and de novo respiratory failure, whereas factors associated with success were good NIV tolerance and high body mass index.

CONCLUSIONS

NIV use has significantly increased in French ICUs during the past 5years, and the success rate has remained unchanged. In patients not previously intubated, NIV is the leading first-line ventilation modality. The proportion of patients successfully treated with NIV increased significantly over the 5-year period (13% vs. 9% of all patients receiving ventilatory support).

Failure of non-invasive ventilation in patients with acute lung injury: observational cohort study

INTRODUCTION

The role of non-invasive positive pressure ventilation (NIPPV) in the treatment of acute lung injury (ALI) is controversial. We sought to assess the outcome of ALI that was initially treated with NIPPV and to identify specific risk factors for NIPPV failure.

METHODS

In this observational cohort study at the two intensive care units of a tertiary center, we identified consecutive patients with ALI who were initially treated with NIPPV. Data on demographics, APACHE III scores, degree of hypoxemia, ALI risk factors and NIPPV respiratory parameters were recorded. Univariate and multivariate regression analyses were performed to identify risk factors for NIPPV failure.

RESULTS

Of 79 consecutive patients who met the inclusion criteria, 23 were excluded because of a do not resuscitate order and two did not give research authorization. Of the remaining 54 patients, 38 (70.3%) failed NIPPV, among them all 19 patients with shock. In a stepwise logistic regression restricted to patients without shock, metabolic acidosis (odds ratio 1.27, 95% confidence interval (CI) 1.03 to 0.07 per unit of base deficit) and severe hypoxemia (odds ratio 1.03, 95%CI 1.01 to 1.05 per unit decrease in ratio of arterial partial pressure of O2 and inspired O2 concentration--PaO2/FiO2) predicted NIPPV failure. In patients who failed NIPPV, the observed mortality was higher than APACHE predicted mortality (68% versus 39%, p < 0.01).

CONCLUSION

NIPPV should be tried very cautiously or not at all in patients with ALI who have shock, metabolic acidosis or profound hypoxemia.

Is there a role for noninvasive ventilation in acute respiratory distress syndrome? A meta-analysis

The role of noninvasive ventilation (NIV) in the management of acute respiratory distress syndrome (ARDS) is controversial. The aim of this study was to assess the effect of NIV on the rate of endotracheal intubation and intensive care unit (ICU) mortality in patients with ARDS. We searched the MEDLINE database for relevant studies published from 1980 to September 2005, and included studies if (a) the design was a randomized controlled trial; (b) patients had ARDS irrespective of the underlying etiology; (c) the interventions compared NIV and medical therapy with medical therapy alone; and (d) outcomes included need for endotracheal intubation and/or ICU survival. The addition of NIV to standard care in the setting of ARDS did not reduce the rate of endotracheal intubation (absolute risk reduction (RR) 13.5%, 95% confidence interval (CI) -5.2% to 31.3%), and had no effect on ICU survival (absolute RR 4.8%, 95% CI -12.8% to 22.1%). However, the trial results were significantly heterogeneous. Thus, current evidence suggests that patients with ARDS are unlikely to have any significant benefits on outcome when NIV is added to standard therapy. However, this analysis is limited by the presence of significant heterogeneity; hence large randomized controlled trials are required to settle this issue.

Respiratory failure after stem cell transplantation: improved outcome with non-invasive ventilation

We retrospectively analyzed the efficacy of non-invasive ventilation in 35 patients with acute hypoxemic respiratory failure after autologous or allogeneic stem cell transplantation (SCT). Non-invasive ventilation was delivered by a standard face mask or helmet. Decisions to intubate were made according to standard criteria. Between 1993 and 2003, 836 patients underwent an autologous or allogeneic bone marrow or SCT. Eighty-two patients developed respiratory failure. Of these, 47 patients were initially intubated and mechanically ventilated. None of these patients survived. Thirty-five patients initially underwent non-invasive ventilation at the bone marrow transplant unit. Seven of these patients survived and were discharged from the hospital (20%). Eleven of the 35 (31%) patients improved within the first 4 h of non-invasive ventilation with respect to oxygenation and were regarded as responders. Seven of these patients survived to hospital discharge (64%), while all non-responders died (P<0.001). In all survivors, the partial pressure of arterial oxygen (PaO2) improved after the initiation of non-invasive ventilation. In non-survivors, PaO2 improved in only 4 of 28 patients (17%) (P<0.0001). Non-invasive ventilation in patients with acute respiratory failure after SCT could improve prognosis in a carefully selected group of patients.

Noninvasive ventilation improves preoxygenation before intubation of hypoxic patients

RATIONALE

Critically ill patients are predisposed to oxyhemoglobin desaturation during intubation.

OBJECTIVES

To find out whether noninvasive ventilation (NIV), as a preoxygenation method, is more effective at reducing arterial oxyhemoglobin desaturation than usual preoxygenation during orotracheal intubation in hypoxemic, critically ill patients.

METHODS

Prospective randomized study performed in two surgical/medical intensive care units (ICUs). Preoxygenation was performed, before a rapid sequence intubation, for a 3-min period using a nonrebreather bag-valve mask (control group) or pressure support ventilation delivered by an ICU ventilator through a face mask (NIV group) according to the randomization.

MEASUREMENTS AND MAIN RESULTS

The control (n = 26) and NIV (n = 27) groups were similar in terms of age, disease severity, diagnosis at admission, and pulse oxymetry values (Sp(O(2))) before preoxygenation. At the end of preoxygenation, Sp(O(2)) was higher in the NIV group as compared with the control group (98 +/- 2 vs. 93 +/- 6%, p < 0.001). During the intubation procedure, the lower Sp(O(2)) values were observed in the control group (81 +/- 15 vs. 93 +/- 8%, p < 0.001). Twelve (46%) patients in the control group and two (7%) in the NIV group had an Sp(O(2)) below 80% (p < 0.01). Five minutes after intubation, Sp(O(2)) values were still better in the NIV group as compared with the control group (98 +/- 2 vs. 94 +/- 6%, p < 0.01). Regurgitations (n = 3; 6%) and new infiltrates on post-procedure chest X ray (n = 4; 8%) were observed with no significant difference between groups.

CONCLUSION

For the intubation of hypoxemic patients, preoxygenation using NIV is more effective at reducing arterial oxyhemoglobin desaturation than the usual method.

Avian influenza (H5N1): implications for intensive care

Background

As influenza A/H5N1 spreads around the globe the risk of an epidemic increases.

Discussion

Review of the cases of influenza A/H5N1 reported to date demonstrates that it causes a severe illness, with a high proportion of patients (63%) requiring advanced organ support. Of these approx. 68% develop multiorgan failure, at least 54% develop acute respiratory distress syndrome, and 90% die. Disease progression is rapid, with a median time from presentation to hospital to requirement for advanced organ support of only 2 days.

Conclusion

The infectious nature, severity and clinical manifestations of the disease and its potential for pandemic spread have considerable implications for intensive care in terms of infection control, patient management, staff morale and intensive care expansion.

Noninvasive Positive Pressure Ventilation in Patients with Respiratory Failure due to Severe Acute Pancreatitis

BACKGROUND

Patients with acute pancreatitis (AP) who require mechanical ventilation have high morbidity and mortality rates. Noninvasive positive pressure ventilation (NPPV) delivered through a mask has become increasingly popular for the treatment of acute respiratory failure (ARF) and may limit some mechanical ventilation complications.

OBJECTIVES

The purpose of this retrospective, observational study was to evaluate our clinical experience with the use of NPPV in AP patients with ARF.

METHODS

From 1997 to 2003, we documented clinical data, gas exchange and outcome of the 62 AP patients admitted to our intensive care unit. Patients who benefited from NPPV (success) were compared with those who failed (intubated).

RESULTS

Twenty-nine patients were intubated at admission and 5 did not develop ARF. Of the 28 patients treated with NPPV, 15 were not intubated (54%). Both groups had a similar PaO(2)/FiO(2) ratio (142 +/- 21 vs. 133 +/- 20; p = 0.127) and severity of illness (Ranson and Balthazar scores). Presence of atelectasis, bilateral alveolar infiltrates and abdominal distension were associated with failure of NPPV. Oxygenation improved and respiratory rate decreased significantly only in the success group. Additionally, the length of stay at the intensive care unit was significantly lower in the success group.

CONCLUSION

NPPV is feasible and safe to treat ARF in selected patients with AP who require ventilatory support.

Non-invasive ventilation as a first-line treatment for acute respiratory failure: "real life" experience in the emergency department

OBJECTIVE

To describe our experience with non-invasive ventilation (NIV) for patients with acute respiratory failure (ARF) in the emergency department (ED).

METHODS

A prospective/retrospective, observational study on 190 patients with ARF (mean +/-SD age 72.2+/-12.9 years, mean APACHE II score 18.9+/-5.9), who received 200 NIV trials in an ED. We analysed the NIV register data (prospectively collected) and medical records (retrospective data abstraction) and evaluated clinical indications for NIV, patient outcomes, and predictive factors for success and death. NIV success was defined as tolerance of the procedure and no need for endotracheal intubation (ETI).

RESULTS

Main indications to NIV were cardiogenic pulmonary oedema (CPE) (70 trials), acute exacerbation of COPD (39), both CPE and acute exacerbation of COPD (11), pneumonia (48), decompensation of obesity/hypoventilation (6), other conditions (26). The procedure was successful in 60.5% of trials. Global mortality was 34.5%, similar to the APACHE II predicted mortality of 32%. ETI rates were 6.5% and tracheostomy rates 1%. The improvement of pH within six hours after NIV initiation was predictive of survival in the hypercapnic group.

CONCLUSIONS

Our results confirm the global efficacy of NIV in an ED setting, and show that, in spite of lower success rate in "real practice" in comparison with RCTs, an intermediate care unit can represent an appropriate and less expensive setting to perform this technique. The low rate of ETI seems to be because of the high number of patients for whom NIV was used as "ceiling" treatment.

Outcomes of Patients With Acute Respiratory Failure After Abdominal Surgery Treated With Noninvasive Positive Pressure Ventilation

OBJECTIVES

Little is known about the physiologic and clinical effects of noninvasive positive pressure ventilation (NPPV) in patients who have acute respiratory failure (ARF) after abdominal surgery. We evaluated our clinical experience with the use of NPPV in the treatment of ARF after abdominal surgery.

METHODS

We prospectively evaluated NPPV use during a 2-year period in a medical-surgical ICU of a university hospital. We documented demographic and diagnostic data, gas exchange, and clinical outcomes. We compared patients who were not intubated to those who were intubated after a trial of NPPV.

RESULTS

Of 72 patients with ARF after abdominal surgery who were treated with NPPV, 48 patients avoided intubation (67%). Patients in the intubated and nonintubated groups had similar demographic characteristics, and similar American Society of Anesthesiologists physical status and simplified acute physiology score II scores at admission. The intubated group had a significantly lower Pa(O2)/fraction of inspired oxygen (Fi(O2)) ratio (123 +/- 62 mm Hg vs 194 +/- 76 mm Hg, p < 0.01) and more extended bilateral alveolar infiltrates (67% vs 31%, p < 0.01) than the non-intubated group. Within the first NPPV observation period, the Pa(O2)/Fi(O2) increased (+ 36 +/- 29% [+/- SD], p = 0.04) and the respiratory rate decreased (28.2 +/- 3.4 breaths/min vs 23.1 +/- 3.8 breaths/min, p < 0.01) significantly only in the non-intubated group. The non-intubated group had significantly lower length of ICU stay (17.3 +/- 10.9 days vs 34.1 +/- 28.5 days, p < 0.01) and mortality rate (6% vs 29%, p < 0.01).

CONCLUSION

NPPV may be an alternative to conventional ventilation in selected patients with ARF after abdominal surgery who require ventilatory support.

Noninvasive positive pressure ventilation reverses acute respiratory failure in select “do-not-intubate” patients

OBJECTIVE

To determine the outcome from the use of noninvasive positive pressure ventilation (NPPV) in "do-not-intubate" (DNI) patients in acute respiratory failure.

DESIGN

Prospective observational study.

SETTING

University-affiliated large medical center.

PATIENTS

All patients with DNI status who received NPPV for a 1-yr period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic, physiologic, and laboratory data were collected before initiation, 2 hrs after initiation, and each morning and evening for as long as NPPV was provided. Data were recorded on 137 episodes of acute respiratory failure in 131 DNI patients. Hospital mortality rate was 37.5% in 24 patients with an exacerbation of chronic obstructive pulmonary disease (COPD), 39% in 28 patients with acute cardiogenic pulmonary edema, 68% in nine patients with non-COPD hypercapnic ventilatory failure, 77% in 13 post-extubation respiratory failure patients, and 86% in 57 patients with hypoxemic respiratory failure. Advanced cancer was present in 40 patients and was associated with increased risk of death (85% mortality rate, p = .002). A score based on the Simplified Acute Physiology Score (SAPS) II and serum albumin level calculated before NPPV was predictive of hospital outcome.

CONCLUSIONS

NPPV is successful in reversing acute respiratory failure and preventing hospital mortality in DNI patients with COPD and cardiogenic pulmonary edema but not in patients with post-extubation failure, hypoxemic respiratory failure, or end-stage cancer. An easy-to-calculate score combining SAPS II and serum albumin level is a good prediction of outcome in DNI patients receiving NPPV.

Physiologic effects of noninvasive ventilation during acute lung injury

A prospective, crossover, physiologic study was performed in 10 patients with acute lung injury to assess the respective short-term effects of noninvasive pressure-support ventilation and continuous positive airway pressure. We measured breathing pattern, neuromuscular drive, inspiratory muscle effort, arterial blood gases, and dyspnea while breathing with minimal support and the equipment for measurements, with two combinations of pressure-support ventilation above positive end-expiratory pressure (10-10 and 15-5 cm H2O), and with continuous positive airway pressure (10 cm H2O). Tidal volume was increased with pressure support, and not with continuous positive airway pressure. Neuromuscular drive and inspiratory muscle effort were lower with the two pressure-support ventilation levels than with other situations (p < 0.05). Dyspnea relief was significantly better with high-level pressure-support ventilation (15-5 cm H2O; p < 0.001). Oxygenation improved when 10 cm H2O positive end-expiratory pressure was applied, alone or in combination. We conclude that, in patients with acute lung injury (1) noninvasive pressure-support ventilation combined with positive end-expiratory pressure is needed to reduce inspiratory muscle effort; (2) continuous positive airway pressure, in this setting, improves oxygenation but fails to unload the respiratory muscles; and (3) pressure-support levels of 10 and 15 cm H2O provide similar unloading but differ in their effects on dyspnea.

Noninvasive bilevel positive pressure ventilation in patients with blunt thoracic trauma

BACKGROUND

Noninvasive bilevel positive pressure ventilation (N-BiPAP) has an established role in providing respiratory support in patients with acute respiratory failure. The significant advantage of N-BiPAP is to avoid endotracheal intubation and its complications. Currently there are no data that support N-BiPAP as first-line treatment in patients with blunt thoracic trauma.

OBJECTIVE

To evaluate the safety and efficacy of N-BiPAP in patients with acute respiratory failure due to blunt thoracic trauma.

METHODS

Prospective observational study. Twenty-two patients with blunt chest trauma (mean injury severity score 26 +/- 9) were studied. N-BiPAP was applied via a tight-fitting full or total-face mask, combined with regional anesthesia in all patients.

RESULTS

N-BiPAP resulted in significant changes in blood gasses, heart rate and breathing frequency at 1 h. Eighteen out of 22 patients avoided intubation and were discharged from the ICU (success group). Four patients met predefined criteria and required intubation (failure group) within 24 h after N-BiPAP. Three of the patients in the failure group survived while 1 developed septic shock and died. The acute response of oxygenation to N-BiPAP differed significantly between groups, being higher in the success group. Complications related to N-BiPAP were minor, consisting of nose bridge injury (1 patient) and gastric distention (1 patient).

CONCLUSIONS

N-BiPAP administration could be a safe and effective method to improve the gas exchange in patients with acute respiratory failure due to blunt thoracic trauma.

Noninvasive ventilation in hypercapnic acute respiratory failure due to chronic obstructive pulmonary disease vs. other conditions: effectiveness and predictors of failure

OBJECTIVE

This study compared the effectiveness of noninvasive ventilation (NIV) and the risk factors for NIV failure in hypercapnic acute respiratory failure (ARF) due to chronic obstructive pulmonary disease (COPD) vs. non-COPD conditions.

DESIGN AND SETTING

Prospective cohort study in the medical intensive care unit of a university hospital.

PATIENTS AND PARTICIPANTS

111 patients with hypercapnic ARF, 43 of whom had COPD exacerbations and 68 other conditions. Baseline characteristics of the two groups were similar.

MEASUREMENTS AND RESULTS

The risk of NIV failure, defined as the need for endotracheal intubation, was significantly lower in COPD than in other conditions (19% vs. 47%). High APACHE II score was an independent predictor of NIV failure in COPD (OR 5.38 per 5 points). The presence of pneumonia (OR 5.63), high APACHE II score (OR 2.59 per 5 points), rapid heart rate (OR 1.22 per 5 beats/min), and high PaCO(2) 1 h after NIV (OR 1.22 per 5 mmHg) were independent predictors of NIV failure in the non-COPD group. Failure of NIV independently predicted mortality (OR 10.53).

CONCLUSIONS

Noninvasive ventilation was more effective in preventing endotracheal intubation in hypercapnic ARF due to COPD than non-COPD conditions. High APACHE II score predicted NIV failure in both groups. Noninvasive ventilation was least effective in patients with hypercapnic ARF due to pneumonia.

Noninvasive Positive-Pressure Ventilation To Treat Hypercapnic Coma Secondary to Respiratory Failure

INTRODUCTION

Hypercapnic coma secondary to acute respiratory failure (ARF) is considered to be a contraindication to the use of treatment with noninvasive positive-pressure ventilation (NPPV). However, intubation exposes these patients to the risk of complications such as nosocomial pneumonia, sepsis, and even death.

PATIENTS AND METHODS

We performed a prospective, open, noncontrolled study to assess the outcomes of NPPV therapy in patients with a Glasgow coma scale (GCS) score of </= 8 points due to ARF. The primary goal of the study was to determine the success of NPPV therapy (defined as a response to therapy allowing the patient to avoid endotracheal intubation, and to survive a stay in the ICU and at least 24 h on a medical ward) in patients with hypercapnic coma, compared to those who started NPPV therapy while awake. The secondary goal of the study was to identify the variables that can predict a failure of NPPV therapy in these patients.

RESULTS

A total of 76 coma patients (80%) responded to NPPV therapy, and 605 patients with GCS scores > 8 responded to therapy (70%; p = 0.04). A total of 25 coma patients died in the hospital (26.3%), and 287 noncoma patients died in the hospital (33.2%; p = 0.17). The variables related to the success of NPPV therapy were GCS score 1 h posttherapy (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.53 to 3.53) and higher levels of multiorgan dysfunction, as measured by the maximum sequential organ failure assessment index score reached during NPPV therapy (OR, 0.72; 95% CI, 0.55 to 0.92).

CONCLUSIONS

We concluded that selected patients with hypercapnic coma secondary to ARF can be treated as successfully with NPPV as awake patients with ARF.

Factores de predicción del éxito de la ventilación no invasiva en el tratamiento del edema agudo de pulmón cardiogénico

BACKGROUND AND OBJECTIVE

Recent studies support the use of non invasive ventilation (NIV) in patients with acute cardiogenic pulmonary edema (ACPE). We aimed to evaluate the factors related to the success of the technique in patients admitted to an intensive care unit (ICU) with ACPE.

PATIENTS AND METHOD

An observational prospective study was performed in ICU.199 consecutive patients were enrolled with ACPE at admission who received treatment with NIV and standardized pharmacological treatment. The success of the NIV was achieved when endotracheal intubation was avoided and patients were alive without dyspnea within and 24 hours after discharge from the ICU. Clinical, physiological and gasometric parameters were analyzed at admission and one hour after starting NIV.

RESULTS

Patient's age was 74 years. 43% were male. The SAPS II was 45. 74.4% of the patients were successfully treated with NIV. 12.6% required endotracheal intubation. In a multivariate analysis, the success of the technique (values expressed as odds ratio [95% confidence interval]) was related to: SAPS II (0.95 [0.91-0.99]); the place of admission (6.78 [1.85-24.79]); value of PCO2 at admission (1.05 [1.01-1.09]); PO2/FiO2 index (1.03 [1.01-1.06]) and respiratory frequency (0.91 [0.84-0.99]) within the first hour; SOFA (acute failure organics score) (0.62 [0.49-0.78]); concomittant acute myocardial infarction (AMI) (0.05 [0.01-0.22]) and number of complications (0.17 [0.47-0.65]). The hospital mortality rate was 32.7%. The non intubation order (0.12 [0.04-0.32]) and the success of the technique (100.03 [28.71-348.47]) were related to the hospital mortality.

CONCLUSIONS

The success of NIV in the treatment of ACPE is related to a lower SAPS II, admission at the emergency department, elevated PCO2 at admission, improvement of the PO2/FiO2 index and the respiratory rate within the first hour. The non intubation order and the success of the technique were related to the hospital mortality.

Acute respiratory failure in the cancer patient: the role of non-invasive mechanical ventilation

The most common cause of ICU admission in patients affected by a hematologic or solid cancer is acute respiratory failure, often associated with a respiratory infection. The prognosis of these critically ill patients is disappointingly low especially if they require endotracheal intubation. In the last 10 years, non-invasive mechanical ventilation (NIV), delivered through a face or nose mask, has been increasingly used as an alternative to invasive ventilation. There is good evidence that, compared to the standard medical therapy alone or with invasive mechanical ventilation, NIV may improve survival and reduce the rate of infectious complications in patients affected by hematologic cancers. Patients with a solid tumor and "reversible" acute respiratory failure are also likely to benefit from NIV, while the use of NIV in palliative care of terminally ill patients still needs to be elucidated. The success of NIV is strictly dependent on its "early" use and on the experience of the staff involved.

How to choose a mechanical ventilator

PURPOSE OF REVIEW

To provide some practical and clinical considerations that may guide users through the decision process when choosing mechanical ventilators

RECENT FINDINGS

Although the complexity of mechanical ventilators is steadily increasing, the importance of many devices developed over the course of the technical evolution is still a matter of discussion. Recent data demonstrate that the technical performance of equivalent ventilators (ie, machines of the same generation and category) is pretty similar, suggesting that the different manufacturers keep in step with new developments. Thus, other factors than technical limitations will probably influence the choice of ventilators. Among them the ability of the staff to understand the rationale of the different devices and controls as well as deal with the complexity of the ventilator may be particularly important.

SUMMARY

Choosing mechanical ventilators should begin by defining the algorithms of how to ventilate a patient. Once this is done, a ventilator should allow the transformation of specific strategies into practice and the adaptation of the mechanical support to the needs of the individual patient. This procedure is crucially important, because ventilator therapy should always be determined by the physician and based on solid physiologic rationales rather than by the technical features of the machine.