Noninvasive ventilation reduces mortality in acute respiratory failure following lung resection

Respiratory failure following pulmonary resection

Improvements in the perioperative management of the patient undergoing pulmonary resections have reduced postoperative complication rates steadily in the last several decades. However, postresection respiratory failure, particularly lung injury with no discernible cause, remains a major cause of morbidity and mortality. Because the incidence of this entity is relatively low, the terminology, pathogenesis, and optimal management are poorly delineated in the literature. The purpose of this review is to describe the criteria used to define postresection lung injury, discuss the possible etiologic factors, and outline currently available treatment strategies.

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.

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.

Appropriate Ventilatory Settings for Thoracic Surgery: Intraoperative and Postoperative

Mechanical ventilation of patients undergoing thoracic surgery is often challenging. These patients frequently have significant underlying comorbidities, including cardiopulmonary disease, and often must undergo 1-lung ventilation. Perioperative respiratory complications are common and are multifactorial in etiology. Increasing evidence suggests that mechanical ventilation is associated with, and may even cause, lung damage in both sick and healthy patients. Gas exchange to provide acceptable end-organ oxygenation remains a primary goal but so too is minimization of risks for acute lung injury. Every ventilator strategy is associated with potential beneficial and adverse side effects. Understanding the impact of various ventilation strategies allows clinicians to provide optimal care for patients.

Noninvasive mechanical ventilation during the weaning process: facilitative, curative, or preventive?

To avoid the complications associated with endotracheal intubation, noninvasive positive-pressure ventilation (NPPV) has been proposed in the management of ventilator weaning in patients with acute respiratory failure (ARF) of various etiologies. Several studies have been performed to assess the benefit of NPPV in various weaning strategies, including permitting early extubation in patients who fail to meet standard extubation criteria (facilitation use), avoiding reintubation in patients who fail extubation (curative use), and preventing extubation failure in nonselected and selected patients (preventive use). NPPV has been successfully used in facilitating early extubation, particularly in patients with chronic obstructive pulmonary disease. In contrast, applying curative NPPV to treat postextubation ARF in nonselected populations may not be effective and could even be deleterious. Early use of NPPV was successful in preventing ARF after extubation, and decreased the need for reintubation in selected patients at risk of developing postextubation ARF. It is important that caregivers clearly differentiate among these application modalities of NPPV. The skills and expertise of both medical and nonmedical personnel are crucial predictive factors for the success of NPPV in the ventilator weaning process.

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.

Mechanical ventilation in patients with hypoxemia due to refractory heart failure

OBJECTIVE

The goal of this study was to evaluate the safety and efficacy of mechanical ventilation (MV), including noninvasive positive pressure ventilation (NPPV) and endotracheal intubation (ETI) in patients with very severe hypoxemia due to refractory heart failure (RHF).

METHODS

In addition to conventional treatment, eighteen patients with hypoxemia due to RHF were assigned to receive NPPV (n=10) or ETI (n=8) based on the severity of their clinical status. Arterial blood gas, PaO(2)/FiO(2), vital signs including respiratory rate (RR), heart rate (HR) and systolic blood pressure (SBP), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) were recorded before and after MV in each group.

RESULTS

The patients in the ETI group showed more severe hypoxemia and respiratory acidosis in comparison with the patients in the NPPV group. Both the NPPV and ETI significantly increased PaO(2), PaO(2)/FiO(2) and arterial oxygen saturation (SaO(2)) (p <0.01) and reduced RR and HR (p <0.01) after MV in comparison to that before MV. Both the NPPV and ETI significantly increased LVEF (p <0.05) and decreased LVEDV (p <0.01) at the time of weaning from MV in comparison to that before MV. Moreover, PaO(2) correlated with LVEF (r=0.882, p=0.01 and r=0.736, p=0.037) while it also inversely correlated with LVEDV (r=-0.645, p=0.044 and r=-0.756, p=0.030) at the time of weaning from MV in the NPPV and ETI groups, respectively. There were two failed cases in the NPPV group. They were transferred immediately to be treated with ETI and were equivalent to the others in the ETI group.

CONCLUSION

Both NPPV and ETI are safe and effective modalities for improving hypoxemia and left heart function in patients with RHF. These results suggest that invasive MV should be applied to very severe patients with RHF as quickly as possible when an expected clinical improvement cannot be obtained by NPPV.

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.

Non-invasive positive pressure ventilation for acute respiratory failure: justified or just hot air?

Non-invasive positive pressure ventilation (NIV) is the provision of mechanical positive airway pressure ventilatory support through the patient's upper airway through mask interface. Conditions in which it has been shown to be effective are acute cardiogenic pulmonary oedema and acute hypercapnic exacerbations of chronic obstructive pulmonary disease. In such conditions, NIV is associated with reduced intensive care unit demands, a reduction in intubation rates, reduced health-care expenditure and improved survival. Other conditions, such as hypercapnia of other cause, hypoxaemic respiratory failure and acute asthma, have supportive, but less conclusive data. Indications, contraindications and guidelines for the use of NIV are discussed.

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.

Noninvasive ventilation in patients with "do-not-intubate" orders: medium-term efficacy depends critically on patient selection

OBJECTIVE

Randomized clinical trials demonstrating benefits of noninvasive ventilation (NIV) systematically exclude patients with "do-not-intubate" (DNI) orders, but in daily clinical practice these patients are frequently treated with NIV. A recent North American study found a 43% hospital survival rate in patients with DNI orders. Our hypothesis was that, due to the very different social and cultural setting, written DNI orders in a southern European country would be restricted to a population with a poor outcome, independently of whether they receive NIV, and we analyzed hospital survival in patients receiving NIV and the impact of DNI orders on survival.

DESIGN AND SETTING

Retrospective cohort study in a general ICU in a university-affiliated hospital.

PATIENTS AND METHODS

All 233 patients treated with NIV during 2002-2004. We recorded clinical characteristics on admission, mortality risk by APACHE II and ICU and hospital outcome, and 6-month outcome.

RESULTS

Hospital survival was 66%. Survival was better in the 199 patients without DNI orders than in the 36 with DNI orders both during hospitalization (74% vs. 26%, OR 7.9) and after 6 months (64% vs. 15%, OR 10.2). In both groups the presence of COPD was associated with better prognosis during hospitalization, but not in the medium-term.

CONCLUSION

Our study suggests that NIV offers low expectations for medium-term survival in DNI patients.

Non-invasive ventilation in chronic obstructive pulmonary disease patients: helmet versus facial mask

RATIONALE

The helmet is a new interface with the potential of increasing the success rate of non-invasive ventilation by improving tolerance.

OBJECTIVES

To perform a physiological comparison between the helmet and the conventional facial mask in delivering non-invasive ventilation in hypercapnic patients with chronic obstructive pulmonary disease.

METHODS

Prospective, controlled, randomized study with cross-over design. In 10 patients we evaluated gas exchange, inspiratory effort, patient-ventilator synchrony and patient tolerance after 30 min of non-invasive ventilation delivered either by helmet or facial mask; both trials were preceded by periods of spontaneous unassisted breathing.

MEASUREMENTS

Arterial blood gases, inspiratory effort, duration of diaphragm contraction and ventilator assistance, effort-to-support delays (at the beginning and at the end of inspiration), number of ineffective efforts, and patient comfort.

MAIN RESULTS

Non-invasive ventilation improved gas exchange (p<0.05) and inspiratory effort (p<0.01) with both interfaces. The helmet, however, was less efficient than the mask in reducing inspiratory effort (p<0.05) and worsened the patient-ventilator synchrony, as indicated by the longer delays to trigger on (p<0.05) and cycle off (p<0.05) the mechanical assistance and by the number of ineffective efforts (p<0.005). Patient comfort was no different with the two interfaces.

CONCLUSIONS

Helmet and facial mask were equally tolerated and both were effective in ameliorating gas exchange and decreasing inspiratory effort. The helmet, however, was less efficient in decreasing inspiratory effort and worsened the patient-ventilator interaction.

Anticipating pulmonary complications after thoracotomy: the FLAM Score

Objective

Pulmonary complications after thoracotomy are the result of progressive changes in the respiratory status of the patient. A multifactorial score (FLAM score) was developed to identify postoperatively patients at higher risk for pulmonary complications at least 24 hours before the clinical diagnosis.

Methods

The FLAM score, created in 2002, is based on 7 parameters (dyspnea, chest X-ray, delivered oxygen, auscultation, cough, quality and quantity of bronchial secretions). To validate the FLAM score, we prospectively calculated scores during the first postoperative week in 300 consecutive patients submitted to posterolateral thoracotomy.

Results

During the study, 60 patients (20%) developed pulmonary complications during the postoperative period. The FLAM score progressively increased in complicated patients until the fourth postoperative day (mean 13.5 ± 11.9). FLAM scores in patients with complications were significantly higher (p < 0.05) at least 24 hours before the clinical diagnosis of complication, compared to FLAM scores in uncomplicated patients. ROC curves analysis showed that the cut-off value of FLAM with the best sensitivity and specificity for pulmonary complications was 9 (area under the curve 0.97). Based on the highest FLAM scores recorded, 4 risk classes were identified with increasing incidence of pulmonary complications and mortality.

Conclusion

Changes in FLAM score were evident at least 24 hours before the clinical diagnosis of pulmonary complications.

FLAM score can be used to categorize patients according to risk of respiratory morbidity and mortality and could be a useful tool in the postoperative management of patients undergoing thoracotomy.

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.

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).

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.

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.

Time of non-invasive ventilation

Non-invasive ventilation (NIV) is a safe, versatile and effective technique that can avert side effects and complications associated with endotracheal intubation. The success of NIV relies on several factors, including the type and severity of acute respiratory failure, the underlying disease, the location of treatment, and the experience of the team. The time factor is also important. NIV is primarily used to avert the need for endotracheal intubation in patients with early-stage acute respiratory failure and post-extubation respiratory failure. It can also be used as an alternative to invasive ventilation at a more advanced stage of acute respiratory failure or to facilitate the process of weaning from mechanical ventilation. NIV has been used to prevent development of acute respiratory failure or post-extubation respiratory failure. The number of days of NIV and hours of daily use differ, depending on the severity and course of the acute respiratory failure and the timing of application. In this review article, we analyse, compare and discuss the results of studies in which NIV was applied at various times during the evolution of acute respiratory failure.

Effects of Gas Leak on Triggering Function, Humidification, and Inspiratory Oxygen Fraction During Noninvasive Positive Airway Pressure Ventilation

OBJECTIVES

During noninvasive positive pressure ventilation (NPPV), the gas leak that commonly occurs around the mask can render NPPV ineffective. We evaluated the effects of gas leak on inspiratory trigger function during NPPV with bilevel pressure and ICU ventilators. In addition, we evaluated the effects of gas leak on fraction of inspired oxygen (Fio(2)) and humidification.

METHODS

Air leak was created at the airway opening of a model lung by establishing several different-size holes in the circuit. During simulated spontaneous breathing, we evaluated inspiratory trigger performance of two bilevel pressure ventilators (BiPAP Vision and BiPAP S/T-D; Respironics; Murrysville, PA) and two ICU ventilators (Puritan-Bennett 7200ae and Puritan-Bennett 840; Tyco Healthcare; Mansfield, MA). Inspiratory delay time and inspiratory trigger pressure were analyzed. Fio(2) at the airway opening and inside the model lung were evaluated during BiPAP S/T-D ventilation at supplemental oxygen flows of 3, 6, 9, 12 and 15 L/min. Measured oxygen concentration was compared to mathematically predicted levels. Finally, using two heated humidifiers, we evaluated the effect of gas leak on humidification.

RESULTS

The bilevel pressure ventilators triggered properly at all levels of gas leak, and inspiratory triggering was more effective than with the ICU ventilators. Delivered Fio(2) with the BiPAP S/T-D ventilator was affected by gas leak and could be predicted mathematically unless the gas leak was large. With large gas leaks, although relative humidity was maintained, absolute humidity decreased.

CONCLUSION

Gas leak affected triggering of ICU ventilators, Fio(2) of the BiPAP S/T-D ventilator, and humidity with both types of humidifiers.

Noninvasive positive pressure ventilation in the intensive care unit: A concise review

OBJECTIVE

To critically assess available high-level clinical studies regarding use of noninvasive positive pressure ventilation in varied intensive care unit settings.

DATA SOURCE

Search of pertinent articles within Ovid MEDLINE from 1975 to 2005, CINAHL from 1982 to 2005, EMBASE from 1988 to 2005, and Web of Science from 1993 to 2005.

STUDY SELECTION

Randomized, controlled clinical trials and cohort studies and observational studies the authors consider important or novel.

DATA EXTRACTION/SYNTHESIS

Performed equally by both authors with the use of an Excel data spreadsheet.

CONCLUSION

There is abundant level I evidence supporting the use of noninvasive positive pressure ventilation in such critical care settings as acute hypercapnic respiratory failure, particularly related to chronic obstructive pulmonary disease, and acute cardiogenic pulmonary edema. We also report on other clinical scenarios in which the data may be somewhat less compelling, but evidence favors a noninvasive positive pressure ventilation trial. Some well designed studies suggest that noninvasive positive pressure ventilation is not an appropriate intervention for patients who have failed endotracheal extubation.

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.

Bilevel noninvasive positive pressure ventilation for acute respiratory failure: Survey of Ontario practice*

OBJECTIVE

To determine physicians' stated practices regarding the use of bilevel noninvasive ventilation (NIV) for acute respiratory failure and the predictors of practice variation.

DESIGN

Cross-sectional postal survey.

SETTING

Province of Ontario, Canada.

PARTICIPANTS

Attending physicians and residents in four specialties at 15 teaching hospitals.

INTERVENTIONS

We used literature searches and focus groups to design questions related to NIV utilization with respect to frequency, location of and indications for use, awareness of supporting literature, and perceived efficacy. We assessed the survey's clinical sensibility and reliability. We used regression analyses to evaluate practice variation among hospitals and specialties and to determine predictors of more frequent NIV use, initiation of and continued use in nonmonitored settings, and use for specific indications.

MEASUREMENTS AND MAIN RESULTS

Three hundred eighty-five (48%) of 808 physicians responded; 242 used NIV. The two most common indications for NIV use were chronic obstructive pulmonary disease and congestive heart failure. NIV guidelines, protocols, or policies were available in 12 of 15 hospitals. We found variation in NIV utilization among specialties but not hospitals. Specialty (critical care and respirology versus internal and emergency medicine), fewer years of postgraduate experience, and a greater number of noninvasive ventilators were predictors of more frequent NIV use (all p < or = .001). Only 6% of respondents reported initiation of use and continued use most frequently in nonmonitored settings, which increased with the number of noninvasive ventilators (p = .02). Physician characteristics such as awareness of the literature were predictive of NIV use for exacerbations of chronic obstructive pulmonary disease, whereas perceived NIV efficacy was predictive of use for many indications, including congestive heart failure.

CONCLUSIONS

Self-reported practice variation for bilevel NIV exists among specialties but not hospitals and differs with respect to frequency, location of use, and use for specific indications. Some factors associated with variation in NIV use may be suitable targets for utilization improvement interventions.

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.

Acute lung injury and acute respiratory distress syndrome after pulmonary resection

The occurrence of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after thoracic surgery are perplexing and persistent problems. Variously described as postpneumonectomy pulmonary edema, noncardiogenic pulmonary edema, and postlung resection pulmonary edema, ALI and ARDS may be considered a single entity, with ALI being the less severe form of ARDS. It is characterized by the acute onset of hypoxemia with radiographic infiltrates consistent with pulmonary edema, without elevations in the pulmonary capillary wedge pressure. Although this syndrome does not occur frequently and is usually without identifiable cause, the mortality is high. However, the phenomenon has not been rigorously studied owing to the low incidence, with primarily retrospective case series reported. Thus, the nomenclature, risks, and pathogenesis are not well defined. Interest in this syndrome has recently been renewed as the rate of other perioperative complications has declined. ALI/ARDS is reviewed with a focus on potential etiologies and the spectrum of available interventions.

Intérêt de la ventilation non invasive (VNI) systématique en post-opératoire immédiat d’une résection pulmonaire pour prévenir les complications pulmonaires chez les patients BPCO (essai POPVNI)

BACKGROUND

Respiratory complications are common following pulmonary resection and cause a significant mortality. The use of non-invasive ventilation (NIV) in acute respiratory insufficiency (ARI) is now well recognised. The prophylactic use of NIV in the absence of ARI and/or hypercapnia may be equally justified for the physiological benefits expected in the post-operative period following pulmonary surgery. The aim of our study therefore is to evaluate the effectiveness of NIV in the prevention of pulmonary complications in the immediate post-operative care of patients with moderate and severe COPD.

METHODS

It will be a multicentre, prospective, randomised, parallel, open ended study of patients with moderate and severe COPD admitted to hospital for pulmonary resection.

EXPECTED RESULTS

To determine whether the setting up of NIV immediately post-operatively reduces the incidence of acute respiratory events (acute respiratory insufficiency) and to identify any sub-groups who receive greater benefit from NIV. This study should establish the place of NIV in the immediate post operative care following pulmonary resection.

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.

Does noninvasive positive pressure ventilation improve outcome in acute hypoxemic respiratory failure? A systematic review

CONTEXT

The results of studies on noninvasive positive pressure ventilation (NPPV) for acute hypoxemic respiratory failure unrelated to cardiogenic pulmonary edema have been inconsistent.

OBJECTIVE

To assess the effect of NPPV on the rate of endotracheal intubation, intensive care unit and hospital length of stay, and mortality for patients with acute hypoxemic respiratory failure not due to cardiogenic pulmonary edema.

DATA SOURCE

We searched the databases of MEDLINE (1980 to October 2003) and EMBASE (1990 to October 2003). Additional data sources included the Cochrane Library, personal files, abstract proceedings, reference lists of selected articles, and expert contact.

STUDY SELECTION

We included studies if a) the design was a randomized controlled trial; b) patients had acute hypoxemic respiratory failure not due to cardiogenic pulmonary edema; c) the interventions compared noninvasive ventilation and standard therapy with standard therapy alone; and d) outcomes included need for endotracheal intubation, length of intensive care unit or hospital stay, or intensive care unit or hospital survival.

DATA EXTRACTION

In duplicate and independently, we abstracted data to evaluate methodological quality and results.

DATA SYNTHESIS

The addition of NPPV to standard care in the setting of acute hypoxemic respiratory failure reduced the rate of endotracheal intubation (absolute risk reduction 23%, 95% confidence interval 10-35%), ICU length of stay (absolute reduction 2 days, 95% confidence interval 1-3 days), and ICU mortality (absolute risk reduction 17%, 95% confidence interval 8-26%). However, trial results were significantly heterogeneous.

CONCLUSION

Randomized trials suggest that patients with acute hypoxemic respiratory failure are less likely to require endotracheal intubation when NPPV is added to standard therapy. However, the effect on mortality is less clear, and the heterogeneity found among studies suggests that effectiveness varies among different populations. As a result, the literature does not support the routine use of NPPV in all patients with acute hypoxemic respiratory failure.

Continuous Positive Airway Pressure Versus Noninvasive Pressure Support Ventilation to Treat Atelectasis After Cardiac Surgery

Atelectasis is common after cardiac surgery and may result in impaired gas exchange. Continuous positive airway pressure (CPAP) is often used to prevent or treat postoperative atelectasis. We hypothesized that noninvasive pressure support ventilation (NIPSV) by increasing tidal volume could improve the evolution of atelectasis more than CPAP. One-hundred-fifty patients admitted to our surgical intensive care unit (SICU) with a Radiological Atelectasis Score >or=2 after cardiac surgery were randomly assigned to receive either CPAP or NIPSV four times a day for 30 min. Positive end-expiratory pressure was set at 5 cm H(2)O in both groups. In the NIPSV group, pressure support was set to provide a tidal volume of 8-10 mL/kg. At SICU discharge, we observed an improvement of the Radiological Atelectasis Score in 60% of the patients with NIPSV versus 40% of those receiving CPAP (P = 0.02). There was no difference in oxygenation (Pao(2)/fraction of inspired oxygen at SICU discharge: 280 +/- 38 in the CPAP group versus 301 +/- 40 in the NIPSV group), pulmonary function tests, or length of stay. Minor complications, such as gastric distensions, were similar in the two groups. NIPSV was superior to CPAP regarding the improvement of atelectasis based on radiological score but did not confer any additional clinical benefit, raising the question of its usefulness for altering outcome.

Clinical review: Noninvasive ventilation in the clinical setting--experience from the past 10 years

This brief review analyses the progress of noninvasive ventilation (NIV) over the last decade. NIV has gained the dignity of first line intervention for acute exacerbation of chronic obstructive pulmonary disease, assuring reduction of the intubation rate, rate of infection and mortality. Despite positive results, NIV still remains controversial as a treatment for acute hypoxemic respiratory failure, largely due to the different pathophysiology of hypoxemia. The infection rate reduction effect achieved by NIV application is crucial for immunocompromised patients for whom the endotracheal intubation represents a high risk. Improvements in skills acquired with experience over time progressively allowed successful treatment of more severe patients.

Salvage intensive care following initial recovery from pulmonary resection: is it justified?

BACKGROUND

There is little objective evidence concerning the outcome of thoracic surgical patients who suffer postoperative complications. We assessed the outcome and cost of care for patients admitted to the intensive care unit after initial recovery from pulmonary resection in a high dependency unit.

METHODS

In a single surgeon's practice, over a 3-year period, 28 patients [22 male, median age 66 years old (range 48-80 years old)] required intensive care admission. Preoperative pulmonary function, reason for initial operation, cause of intensive care admission, interventions, and outcome in hospital and at 6 months was studied. The cost of care provided was estimated.

RESULTS

The major reason for intensive care admission was respiratory failure; 61% of patients required mechanical ventilation and 54% renal support. All 4 patients who required both mechanical ventilation and hemofiltration died. Intensive care and 6-month survival were 54% and 36%, respectively. On univarate analysis mechanical ventilation and renal support predicted both hospital mortality (p < 0.001 and p = 0.003) and 6-month mortality (p = 0.003 and p = 0.01). Patients who died in intensive care stayed longer (median stay 9 vs 3 days; p = 0.04) at a higher cost per patient (median cost $6975 vs $19,375; p = 0.04) than those who survived.

CONCLUSIONS

Patients who suffer complications after lung resection and require salvage intensive care, particularly mechanical ventilation, have a poor prognosis. In the light of this data the onset of two-organ failure should prompt an informed discussion as to whether escalation of treatment is in the patient's best interest.

[Phoning study about postoperative practice and application of non-invasive ventilation]

OBJECTIVES

Incidence and management of positive pressure non-invasive ventilation (NIV) in intensive care unit (ICU) in the postoperative period.

STUDY DESIGN

Phoning study performed on September 2001 in 60 ICU of south of France (public: 47, private: 13, medical: 11, surgical: 20, medical-surgical: 29), which were randomized from a national list.

RESULTS

NIV was used currently on 55% and casually on 35% of the units. Ten percent of ICU, which never use NIV, were surgical on 83% with a lower number of bed (7 +/- 3 vs. 12 +/- 5). The most often humidification device used was a Heat and Moisture Exchanger (HME) (52%), a Heated Humidifier (HH) (26%), either (4%) and none device (19%). ICU that never used a humidification device used a home ventilator in 30%. Ventilators used were more often heavy ICU ventilators (80%) with a facial mask (89%). NIV was performed exclusively by physicians in 15% of cases and in collaboration after the first application in 71% of cases. Sixty-nine % of intensivists used NIV as a first choice for the treatment of acute postoperative respiratory failure and 54% of intensivists for the treatment of postoperative atelectasis.

CONCLUSION

Use of NIV increases in ICU, particularly in surgical units. Practices are different between ICU. An HME is the most frequently humidification device used.

Risk Factors for Acute Lung Injury After Thoracic Surgery for Lung Cancer

Acute lung injury (ALI) may complicate thoracic surgery and is a major contributor to postoperative mortality. We analyzed risk factors for ALI in a cohort of 879 consecutive patients who underwent pulmonary resections for non-small cell lung carcinoma. Clinical, anesthetic, surgical, radiological, biochemical, and histopathologic data were prospectively collected. The total incidence of ALI was 4.2% (n = 37). In 10 cases, intercurrent complications (bronchopneumonia, n = 5; bronchopulmonary fistula, n = 2; gastric aspiration, n = 2; thromboembolism, n = 1) triggered the onset of ALI 3 to 12 days after surgery, and this was associated with a 60% mortality rate (secondary ALI). In the remaining 27 patients, no clinical adverse event preceded the development of ALI-0 to 3 days after surgery-that was associated with a 26% mortality rate (primary ALI). Four independent risk factors for primary ALI were identified: high intraoperative ventilatory pressure index (odds ratio, 3.5; 95% confidence interval, 1.7-8.4), excessive fluid infusion (odds ratio, 2.9; 95% confidence interval, 1.9-7.4), pneumonectomy (odds ratio, 2.8; 95% confidence interval, 1.4-6.3), and preoperative alcohol abuse (odds ratio, 1.9; 95% confidence interval, 1.1-4.6). In conclusion, we describe two clinical forms of post-thoracotomy ALI: 1). delayed-onset ALI triggered by intercurrent complications and 2). an early form of ALI amenable to risk-reducing strategies, including preoperative alcohol abstinence, lung-protective ventilatory modes, and limited fluid intake.

IMPLICATIONS

In an observational study including all patients undergoing lung surgery, we describe two clinical forms of acute lung injury (ALI): a delayed-onset form triggered by intercurrent complications and an early form associated with preoperative alcohol consumption, pneumonectomy, high intraoperative pressure index, and excessive fluid intake over the first 24 h.