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Postoperative Respiratory Failure After Cardiac Surgery: Use of Noninvasive Ventilation
Postoperative Respiratory Failure After Cardiac Surgery: Use of Noninvasive Ventilation Manuel García-Delgado, MD, Inés Navarrete, MD, Maria José García-Palma, MD, and Manuel Colmenero, MD Objectives: To analyze the use of noninvasive ventilation (NIV) in respiratory failure after extubation in patients after cardiac surgery, the factors associated with respiratory failure, and the need for reintubation. Design: Retrospective observational study. Setting: Intensive care unit in a university hospital. Participants: Patients (n ⴝ 63) with respiratory failure after extubation after cardiac surgery over a 3-year period. Interventions: Mechanical NIV. Measurements and Main Results: Demographic and surgical data, respiratory history, causes of postoperative respiratory failure, durations of mechanical ventilation and spontaneous breathing, gas exchange values, and the mortality rate were recorded. Of 1,225 postsurgical patients, 63 (5.1%) underwent NIV for respiratory failure after extubation. The median time from extubation to the NIV application was 40 hours (18-96 hours). The most frequent cause of
respiratory failure was lobar atelectasis (25.4%). The NIV failed in 52.4% of patients (33/63) who had a lower pH at 24 hours of treatment (7.35 v 7.42, p ⴝ 0.001) and a higher hospital mortality (51.5% v 6.7%, p ⴝ 0.001) than those in whom NIV was successful. An interval <24 hours from extubation to NIV was a predictive factor for NIV failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.9), whereas obesity was associated with NIV success (odds ratio, 0.22; 95% confidence interval, 0.05-0.91). Conclusions: Reintubation was required in half of the NIVtreated patients and was associated with an increased hospital mortality rate. Early respiratory failure after extubation (<24 hours) is a predictive factor for NIV failure. © 2012 Elsevier Inc. All rights reserved.
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are and are not likely to benefit from this therapy, thereby improving the indications for its application. The objective of this study was to investigate the use of NIV in the management of respiratory failure after extubation after cardiac surgery, recording the reintubation rate after NIV, and analyzing the factors associated with NIV failure in this patient population.
LMOST ALL CARDIAC SURGICAL patients have some degree of postoperative lung dysfunction. Most have an adequate pulmonary reserve and tolerate this dysfunction well, with minimal effects on oxygenation or breathing. In some patients, however, including those with a history of respiratory disease or with postoperative pneumonia or cardiogenic pulmonary edema, respiratory function can be impaired severely. This deterioration poses a serious problem associated with a longer hospital stay and higher mortality and morbidity. In the early postoperative phase, oxygenation can be impaired by ventilation/perfusion ratio changes and intrapulmonary shunt1; the possible factors include general anesthesia, the receipt of central respiratory depressants, median sternotomy, the presence of drainage tubes, cardiopulmonary bypass, blood-derivative transfusion, diaphragm dysfunction, and comorbidities, especially chronic obstructive pulmonary disease (COPD) and obesity. In recent years, protocols have included the presurgical assessment of the respiratory impairment risk,2,3 and strategies have been developed to decrease pulmonary complications, including the use of early extubation4 or minimally invasive surgery.5 The use of noninvasive ventilation (NIV) in acute respiratory failure has become widespread in recent years, and published data have suggested that it improves oxygenation and can decrease the reintubation rate in medical6 and surgical7,8 patients. NIV is ordered routinely in intensive care units (ICUs), where it has demonstrated its effectiveness to treat acute respiratory failure, especially in patients with COPD,9 acute heart failure,10 and immunodepression.11 It has been used for respiratory failure after extubation in multiple surgical settings, such as abdominal surgery,12 pulmonary resection,13 and cardiac surgery,14 achieving improvements in oxygenation and decreases in the reintubation rate. The authors hypothesized that the mechanisms underlying respiratory failure after cardiac surgery (eg, acute heart failure, pneumonia, and acute respiratory distress syndrome) are similar to those observed in other conditions for which NIV has proved useful. Given the high NIV failure rate in clinical practice, there is a need to identify subgroups of patients who
KEY WORDS: acute respiratory failure, cardiac surgery procedures, noninvasive ventilation, postoperative, reintubation
METHODS This observational study was conducted in a university hospital ICU to which all adult cardiac surgical patients are transferred from the operating room. The hospital has 1,200 beds and serves a population of 450,000 inhabitants, and the ICU has 42 beds and admits about 2,000 patients annually, of whom around 400 are postoperative cardiac surgical patients. Data were gathered retrospectively on patients admitted from September 2006 through September 2009 from the computerized ICU patient database. Data were gathered on demographics (age, sex, body mass index [BMI]), surgical variables (type of surgery, duration of cardiopulmonary bypass), respiratory history (COPD, obstructive sleep apnea syndrome, tobacco consumption, use of domiciliary NIV), causes of postoperative respiratory failure (atelectasis, acute cardiogenic edema, acute lung injury, respiratory pump failure with hypercapnia [partial pressure of arterial carbon dioxide {PaCO2} ⬎45 mmHg], pneumonia, pneumothorax, pleural effusion, or other), durations of mechanical ventilation (MV) (invasive and noninvasive), and spontaneous breathing, gas exchange values, reintubation rate, and hospital mortality. The criterion for NIV application was the onset of acute respiratory failure after initial extubation, defined by ⱖ1 of the following: hypoxemia (oxygen saturation [SaO2] ⬍90% or partial pressure of arterial oxygen ⬍80 mmHg with an inspired oxygen fraction [FIO2] ⬎0.5), respiratory acidosis (pH ⬍7.35 with PaCO2 ⬎45), a respiratory
From the Intensive Care Unit, Hospital Universitario Virgen de las Nieves, Granada, Spain. Address reprint requests to Manuel García-Delgado MD, Intensive Care Unit, Hospital Universitario Virgen de las Nieves, Avenida Fuerzas Armadas, 2, 18014 Granada, Spain. E-mail: mjgardel@ telefonica.net © 2012 Elsevier Inc. All rights reserved. 1053-0770/2603-0016$36.00/0 doi:10.1053/j.jvca.2011.11.007
Journal of Cardiothoracic and Vascular Anesthesia, Vol 26, No 3 (June), 2012: pp 443-447
443
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GARCÍA-DELGADO ET AL
Total ICU postsurgical populaon (n=1225) Paents dying under MV
and never extubated (n=62)
Extubated paents
(n=1163) ICU discharge
without new MV (n=1076)
Respiratory failure
considered a success when reintubation was not required and a failure when reintubation and invasive MV were necessary. Arterial blood samples for gas exchange measurements (partial pressure of arterial oxygen, PaCO2, and pH) were drawn at ⬍30 minutes before the mask was placed for NIV and at 4 to 6 and 24 hours after NIV initiation. ABL800-flex analyzers (Radiometer, Copenhagen, Denmark) were used for arterial gas exchange measurements. Qualitative variables were expressed as frequency and percentage and quantitative variables as mean ⫾ standard deviation when the data distribution was normal according to the Kolmogorov-Smirnov test or as median (interquartile range) when it was not. Student’s t and 2 tests were used to compare means of continuous and qualitative variables, respectively, and Student’s test for the related variables to analyze gas exchange variables as a function of time. The nonparametric MannWhitney test was used for variables that were not normally distributed. A logistic regression multivariate model was constructed to identify predictive factors for reintubation. A p value ⬍0.05 was considered statistically significant.
with MV applicaon
RESULTS
(n=87)
Of 1,225 patients admitted to the ICU after cardiac surgery during the 3-year study period, 63 (5.1%) were treated with NIV for respiratory failure after the first extubation (Fig 1). Table 1 presents the baseline characteristics and histories of these patients.
Invasive mechanical venlaon
Noninvasive venlaon
(n=24)
(n=63)
Fig 1. Flow diagram of the study population. MV, mechanical ventilation; ICU, intensive care unit.
Table 1. Baseline Characteristics of Patients Treated With Noninvasive Ventilation (n ⴝ 63) Mean ⫾ SD
rate ⬎25 beats/min, or clinical signs of increased respiratory workload or muscle fatigue (eg, use of accessory muscles, intercostal indrawing, or paradoxic abdominal movement). The criterion for reintubation was an observation of one of the following: cardiac arrest; respiratory arrest; consciousness impairment with an irregular respiratory rate or gasping for air; severe intolerance of NIV; hemodynamic instability (systolic blood pressure ⬍70 mmHg despite adequate volume supply and use of vasopressors, heart rate ⬍50 beats/min); no improvement in hypoxemia (SaO2 ⬍90% despite an increased FIO2), hypercapnia, or decreased pH; no improvement in clinical signs of fatigue; or the inability to clear secretions. The decision to reintubate was made by the treating physician. NIV was withdrawn if all the following conditions were met: the disappearance of the clinical signs of excessive respiratory work and muscle fatigue, a decreased respiratory rate, and improved respiratory acidosis (pH ⬎7.35 and PaCO2 ⬍45 mmHg) and hypoxemia (SaO2 ⱖ92% with FIO2 ⱕ0.5). Bilevel positive airway pressure Vision ventilators (Respironics, Inc, Murrysville, PA) were used, always with oronasal masks. The authors’ ICU has ⬎15 years’ experience with NIV in postoperative and respiratory patients, and all medical/nursing staff can apply this procedure. The initial ventilator support was 4 to 6 cmH2O of expiratory positive airway pressure and 10 to 14 cmH2O of inspiratory positive airway pressure. In patients with persistent hypoxemic respiratory failure (SaO2 ⬍90%), the expiratory positive airway pressure was increased in steps of 2 cmH2O. The minimum FIO2 level required to maintain a SaO2 ⬎92% was used. Patients with hypercapnic respiratory failure (PaCO2 ⬎45 mmHg) required increments of 2 cmH2O in the inspiratory positive airway pressure level to adjust the tidal volume and breathing rate. The procedure was
Age (y) Sex Male Female BMI (kg/m2) ⬎30 ⱕ30 Not recorded Respiratory history COPD Smoking tobacco Domiciliary NIV OSAS Urgent surgery Type of surgery Valve CABG CABG ⫹ valve Others CPB time (min) Causes of respiratory failure Lobar atelectasis Acute cardiogenic edema ALI/ARDS Hypercapnic pump failure Pneumonia Others (pneumothorax, shock)
n (%)
66 ⫾ 11 31 (49.2) 32 (50.8) 31 (49.2) 29 (46.0) 3 (4.8) 7 (11.1) 13 (20.6) 1 (1.6) 1 (1.6) 18 (28.6) 37 (58.7) 10 (15.9) 5 (7.9) 11 (17.5) 138 ⫾ 68 16 (25.4) 15 (23.8) 8 (12.7) 15 (23.8) 5 (7.9) 11 (17.5)
Abbreviations: ALI/ARDS, acute lung injury/acute respiratory distress syndrome; BMI, body mass index; CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; NIV, noninvasive ventilation; OSAS, obstructive sleep apnea syndrome; SD, standard deviation.
NIV FOR POSTOPERATIVE RESPIRATORY FAILURE
445
Table 2. Differences Between Groups for Success and Failure in Noninvasive Ventilation
Women (%) Urgent surgery (%) Type of surgery (%) Valve CABG CABG ⫹ valve Others Respiratory history (%) COPD Smoking tobacco Domiciliary NIV OSAS Obesity (BMI ⬎30 kg/m2) Cause of respiratory failure (%) Pneumonia ALI/ARDS Acute cardiogenic edema Lobar atelectasis Hypercapnic failure Others Age (y) CPB time (min) Initial MV time (h)
NIV Success (n ⫽ 30)
NIV Failure (n ⫽ 33)
50.0 20.0
51.5 36.4
63.3 20.0 6.7 10.0
54.5 12.1 9.1 24.2
10.0 20.0 3.3 3.3 66.7
12.1 21.2 0.0 0.0 39.4
10.0 10.0 16.7 36.7 16.7 20.0 65 ⫾ 12 128 ⫾ 90 115 ⫾ 174
6.1 15.2 15.2 15.2 30.3 36.0 67 ⫾ 9 113 ⫾ 67 145 ⫾ 167
p Value
NS NS NS
NS
7.40 ⫾ 0.08; p ⫽ 0.03) and 24 hours (7.38 ⫾ 0.08 v 7.42 ⫾ 0.05; p ⫽ 0.006). In the group requiring reintubation, no significant changes versus baseline were observed at either time point. After 24 hours of NIV, the pH was significantly lower in the patients who required intubation than in those who did not (7.35 ⫾ 0.06 v 7.42 ⫾ 0.05; p ⫽ 0.001). In the multivariate regression analysis, a duration of spontaneous breathing (from extubation to NIV application) ⬍24 hours emerged as a predictive factor for NIV failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.9; p ⫽ 0.02), whereas obesity (BMI ⬎30 kg/m2) was found to be a predictive factor for NIV success (odds ratio, 0.22; 95% confidence interval, 0.05-0.91; p ⫽ 0.03). DISCUSSION
NS
NS NS NS
Abbreviations: ALI/ARDS, acute lung injury/acute respiratory distress syndrome; BMI, body mass index; CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; CPB, cardiopulmonary bypass; MV, mechanical ventilation; NIV, noninvasive ventilation; NS, not significant; OSAS, obstructive sleep apnea syndrome.
In the postoperative unit, the median duration of the initial MV (from surgery to extubation) was 8 hours (range, 5-24 hours) for all patients. In contrast, the median time of the initial MV was 38 hours (range, 8-211 hours) and the duration of spontaneous breathing (from extubation to NIV application) was 40 hours (range, 18-96 hours) in this subgroup of 63 patients. The global hospital mortality rate in this subgroup was 30.2% (n ⫽ 19). Reintubation was required by 33 patients, for an NIV failure rate of 52.4%; the hospital mortality was significantly higher (51.5% v 6.7%, p ⫽ 0.001) and the duration of NIV therapy was nonsignificantly longer (44 hours, 10-75 hours, v 22 hours, 10-58 hours; p ⫽ 0.51) in these patients (NIV failures) than in those who did not require reintubation (NIV successes). There was a higher frequency of a BMI ⬎30 kg/m2 (66.7% v 39.4%; p ⫽ 0.03) and a larger percentage of patients with lobar atelectasis as the cause of respiratory failure (36.7% v 15.2%; p ⫽ 0.049) among the NIV successes than among the NIV failures. No significant intergroup differences were found for the remaining clinical variables (Table 2). There were no intergroup differences in gas exchange data before NIV therapy (Table 3, Fig 2). In the group not requiring reintubation, an improvement in oxygenation (partial pressure of arterial oxygen/FIO2) versus baseline was observed at 6 hours (154 ⫾ 88 v 207 ⫾ 100; p ⫽ 0.01) and 24 hours (154 ⫾ 88 v 213 ⫾ 92; p ⫽ 0.01) of NIV, and an improvement in pH was recorded at 6 hours (7.38 ⫾ 0.08 v
The main findings of the present study were that reintubation was necessary for around 50% of postoperative cardiac surgical patients treated with NIV for respiratory failure after extubation and that NIV failure was associated with an increased mortality rate. The early onset (⬍24 hours) of respiratory failure after extubation was associated with NIV failure, and obesity was associated with NIV success. Reported NIV failure rates vary and depend on multiple factors, such as the experience of the medical teams, the type of patient population, the severity of the illness, and the timing of NIV application (before or after the onset of respiratory failure). NIV has shown greater benefits in medical patients with COPD or cardiogenic pulmonary edema, with low intubation rates of around 15% in most cases.15,16 There has been greater variability in respiratory failure after extubation, with reports of NIV failure rates ranging from 10% to 72%.17-20 In one study of patients in a postoperative recovery room after elective surgery (only 7.5% of cardiovascular surgeries), none of the 83 patients treated with NIV required reintubation.21 The cardiorespiratory status of postoperative cardiac surgical patients is less stable and is aggravated by the effects of cardiopulmonary bypass on the ventilation/perfusion ratio and extravascular lung water. The duration of initial MV (38 hours) was much longer in the present subgroup of patients re-
Table 3. Gas Exchange Values in Groups of Success and Failure of Noninvasive Ventilation
PaO2/FIO2 before NIV PaCO2 before NIV pH before NIV PaO2/FIO2 at 6 hours PaCO2 at 6 hours pH at 6 hours PaO2/FIO2 at 24 hours PaCO2 at 24 hours pH at 24 hours
NIV Success
NIV Failure
p Value
154 ⫾ 88 46 ⫾ 15 7.38 ⫾ 0.08 207 ⫾ 100* 44 ⫾ 13 7.40 ⫾ 0.08† 213 ⫾ 92* 42 ⫾ 10 7.42 ⫾ 0.05‡
149 ⫾ 47 45 ⫾ 9 7.36 ⫾ 0.08 186 ⫾ 81 43 ⫾ 9 7.36 ⫾ 0.08 187 ⫾ 66 44 ⫾ 9 7.35 ⫾ 0.06
NS NS NS NS NS NS NS NS 0.001
NOTE. At 6 hours, n ⫽ 29 in the NIV success group and n ⫽ 30 in the NIV failure group; at 24 hours, n ⫽ 28 in the NIV success group and n ⫽ 22 in the NIV failure group. Abbreviations: FIO2, fraction of inspired oxygen; NIV, noninvasive ventilation; NS, not significant; PaCO2, partial pressure of arterial carbon dioxide; PaO2, partial pressure of arterial oxygen. *p ⫽ 0.01, †p ⫽ 0.03, ‡p ⫽ 0.006 versus value before NIV.
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GARCÍA-DELGADO ET AL
PaO2 / FiO2
250
*
200
*
150 100 50
Pa CO2 (mmHg)
60 50 40
30 20 7,5
8
7,45
pH
# 7,4 7,35 7,3
Pre-NIV
6h
24 h
Fig 2. Gas exchange values in the NIV success (solid line) and NIV failure (dashed line) groups plotted against time. Mean values are shown. FIO2, fraction of inspired oxygen; NIV, noninvasive ventilation; PaCO2, partial pressure of arterial carbon dioxide; PaO2, partial pressure of arterial oxygen. * p ⴝ 0.01, # p ⴝ 0.03 and ⴥ p ⴝ 0.006 versus value before NIV.
quiring NIV than usually observed in the authors’ unit, where extubation is expected to take place in the first 8 to 12 hours. This finding indicates the higher frequency of postoperative complications in these patients, their more severe and unstable condition, and the greater possibility of NIV failure. Prolonged postoperative MV has been associated with higher rates of acute respiratory failure in cardiac surgical patients.22 Obesity is considered a risk factor for respiratory complications.23 Postoperative respiratory failure is increased in obese patients by their supine position during prolonged surgery, greater propensity to alveolar collapse and obstructive sleep apnea syndrome, and higher sensitivity to the respiratory depressive effect of sedating drugs and opiates.24 The benefits of NIV in obese patients are well documented. Joris et al12 reported that NIV increased the peak expiratory flow rate, forced vital capacity, and SaO2 on the first day after gastroplasty. El-Solh et al20 applied NIV immediately after extubation in severely obese patients (BMI ⱖ35 kg/m2) and found a decrease
in the respiratory failure rate and a tendency to a lower hospital mortality rate in the subgroup of patients with hypercapnia, which were attributable to increased lung volumes and lower atelectasis decreasing rates. The timing of postoperative NIV treatment is an important issue in evaluating its clinical effectiveness. Some clinical trials have found that the application of NIV therapy after the onset of respiratory failure produces no improvement in reintubation or mortality. Keenan et al19 studied a heterogenous group of (noncardiac surgical) patients who developed respiratory failure ⬍48 hours after extubation and found no difference in reintubation rates (69% v 72%; p ⫽ 0.79), hospital mortality, MV duration, or hospital stay between patients selected randomly for NIV treatment or standard therapy (supplemental oxygen, aggressive physiotherapy, and pharmacotherapy). A larger, multicenter study reported a similar reintubation rate (48%) between NIV-treated patients and those receiving standard treatment but found a higher ICU mortality rate in the former (25% v 14%; p ⫽ 0.048).18 However, the outcomes were superior when NIV was applied immediately after extubation, before the onset of respiratory failure. In a study of patients at high risk of respiratory failure after extubation,25 lower reintubation (8.3% v 24.4%; p ⫽ 0.02) and mortality (⫺10%; p ⬍ 0.01) rates were found in patients treated with NIV immediately after extubation than in those receiving standard medical treatment. Likewise, in a heterogenous group of mostly medical patients,26 the early use of NIV decreased the rates of respiratory failure after extubation (16% v 33%; p ⫽ 0.02) and ICU mortality (3% v 14%; p ⫽ 0.01), especially in patients with hypercapnia. Hypercapnic patients and those with chronic respiratory disease especially benefited from NIV therapy immediately after extubation.27,28 Although NIV was less effective in patients who required NIV earlier in the present study, this does not imply that its early application after extubation is less effective, but rather that NIV failure is more frequent when the respiratory failure occurs within 24 hours of extubation. This can be considered an extubation failure, which is associated with a persistence of the causes of respiratory failure or polyneuropathy, among other conditions. Studies have demonstrated that the prophylactic use of nasal continuous positive airway pressure improves oxygenation in postoperative cardiac surgical patients compared with conventional oxygen therapy14 and decreases the incidence of pneumonia, reintubation, and ICU readmission.29 In a recent study, the application of NIV in cardiac surgical patients developing hypoxemic respiratory failure improved their oxygenation and decreased the incidence of lung infections compared with patients with acute respiratory failure requiring immediate reintubation.30 The NIV failure rate was 22% to 25%, lower than in the present series, but the NIV application produced more complications related to the sternal wound compared with patients who received MV immediately. The limitations of the present study included its retrospective nature and the possible bias involved in gathering information from databases. For instance, the frequency of obstructive sleep apnea syndrome usually is underestimated in retrospective studies.20 There was a large proportion of hypercapnic respiratory failure in the present series, which likely was caused by the
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late application of NIV in hypoxemic respiratory failure rather than by the patients’ respiratory history, which may have contributed to the high reintubation rate found. A delay in reversing respiratory failure is associated with worse outcomes,31 and this is valid for the period before NIV (respiratory distress) and the period with NIV (in patients not treated effectively). In the present patients, NIV failure was associated with a longer duration of NIV treatment, and some patients possibly should have been reintubated earlier. The lack of randomized trials means that conclusions cannot be drawn on the effectiveness of NIV to avoid reintubation in
cardiac surgical patients with postoperative respiratory failure,8 but it appears useful in certain patient groups, such as the obese, and when applied at the appropriate time. Perhaps patients with respiratory failure soon after extubation (⬍24 hours) should be reintubated because of the high likelihood of NIV failure. ACKNOWLEDGMENTS The authors are grateful to Richard Davies for assistance with the English version of this report.
REFERENCES 1. Ng CS, Wan S, Yim AP, et al: Pulmonary dysfunction after cardiac surgery. Chest 121:1269-1277, 2002 2. Légaré JF, Hirsch GM, Buth KJ, et al: Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting. Eur J Cardiothorac Surg 20:930-936, 2001 3. Filsoufi F, Rahmanian PB, Castillo JG, et al: Predictors and early and late outcomes of respiratory failure in contemporary cardiac surgery. Chest 133:713-721, 2008 4. Meade MO, Guyatt G, Butler R, et al: Trials comparing early vs late extubation following cardiovascular surgery. Chest 120:445S453S, 2001 5. Foghsgaard S, Gazi D, Bach K, et al: Minimally invasive aortic valve replacement reduces atelectasis in cardiac intensive care. Acute Card Care 11:169-172, 2009 6. Honrubia T, García López FJ, Franco N, et al: Noninvasive vs conventional mechanical ventilation in acute respiratory failure: A multicenter, randomized controlled trial. Chest 128:3916-3924, 2005 7. Squadrone V, Coha M, Cerutti E, et al: Continuous positive airway pressure for treatment of postoperative hypoxemia: A randomized controlled trial. JAMA 293:589-595, 2005 8. Chiumello D, Chevallard G, Gregoretti C: Non-invasive ventilation in postoperative patients: A systematic review. Intensive Care Med 37:918-929, 2011 9. Lightowler JV, Wedzicha JA, Elliott MW, et al: Non-invasive positive pressure ventilation to treat respiratory failure resulting from exacerbations of chronic obstructive pulmonary disease: Cochrane systematic review and meta-analysis. BMJ 326:185-189, 2003 10. Masip J, Roque M, Sánchez B, et al: Noninvasive ventilation in acute cardiogenic pulmonary edema: Systematic review and metaanalysis. JAMA 294:3124-3130, 2005 11. Hilbert G, Gruson D, Vargas F, et al: Noninvasive ventilation in immunosuppressed patients with pulmonary infiltrates, fever, and acute respiratory failure. N Engl J Med 344:481-487, 2001 12. Joris JL, Sottiaux TM, Chiche JD, et al: Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on the postoperative pulmonary restrictive syndrome in obese patients undergoing gastroplasty. Chest 111:665-670, 1997 13. Auriant I, Jallot A, Hervé P, et al: Noninvasive ventilation reduces mortality in acute respiratory failure following lung resection. Am J Respir Crit Care Med 164:1231-1235, 2001 14. Lopes CR, Brandao CMA, Nozawa E, et al: Benefits of noninvasive ventilation after extubation in the postoperative period of heart surgery. Rev Bras Cir Cardiovasc 23:344-350, 2008 15. Plant PK, Owen JL, Elliott MW: Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: A multicentre randomised controlled trial. Lancet 355:1931-1935, 2000 16. Masip J, Betbesé AJ, Páez J, et al: Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardio-
genic pulmonary oedema: A randomised trial. Lancet 356:2126-2132, 2000 17. Badiger R, Green M, Hackwood H, et al: Non-invasive ventilation in surgical patients in a district general hospital. J Anesth 59:967-970, 2004 18. Esteban A, Frutos-Vivar F, Ferguson ND, et al: Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med 350:2452-2460, 2004 19. Keenan SP, Powers C, McCormack DG, et al: Noninvasive positive-pressure ventilation for postextubation respiratory distress: A randomized controlled trial. JAMA 287:3238-3244, 2002 20. El-Solh AA, Aquilina A, Pineda L, et al: Noninvasive ventilation for prevention of post-extubation respiratory failure in obese patients. Eur Respir J 28:588-595, 2006 21. Battisti A, Michotte JB, Tassaux D, et al: Non-invasive ventilation in the recovery room for postoperative respiratory failure: A feasibility study. Swiss Med Wkly 135:339-343, 2005 22. Kilger E, Möhnle P, Nassau K, et al: Noninvasive mechanical ventilation in patients with acute respiratory failure after cardiac surgery. Heart Surg Forum 13:E91-E95, 2010 23. Akinnusi ME, Pineda LA, El Solh AA: Effect of obesity on intensive care morbidity and mortality: A meta-analysis. Crit Care Med 36:151-158, 2008 24. Benumof JL: Obstructive sleep apnea in the adult obese patient: Implications for airway management. J Clin Anesth 13:144-156, 2001 25. Nava S, Gregoretti C, Fanfulla F, et al: Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med 33:2465-2470, 2005 26. Ferrer M, Valencia M, Nicolas JM, et al: Early noninvasive ventilation averts extubation failure in patients at risk: A randomized trial. Am J Respir Crit Care Med 173:164-170, 2006 27. Ferrer M, Sellarés J, Valencia M, et al: Non-invasive ventilation after extubation in hypercapnic patients with chronic respiratory disorders: Randomised controlled trial. Lancet 374:1082-1088, 2009 28. Hilbert G, Gruson D, Portel L, et al: Noninvasive pressure support ventilation in COPD patients with postextubation hypercapnic respiratory insufficiency. Eur Respir J 11:1349-1353, 1998 29. Zarbock A, Mueller E, Netzer S, et al: Prophylactic nasal continuous positive airway pressure following cardiac surgery protects from postoperative pulmonary complications: A prospective, randomized, controlled trial in 500 patients. Chest 135:1252-1259, 2009 30. Boeken U, Schurr P, Kurt M, et al: Early reintubation after cardiac operations: Impact of nasal continuous positive airway pressure (nCPAP) and noninvasive positive pressure ventilation (NPPV). J Thorac Cardiovasc Surg 58:398-402, 2010 31. Epstein SK, Ciobotaru RL: Independent effects of etiology of failure and time of reintubation on outcome for patients failing extubation. Am J Respir Crit Care Med 4:161-165, 1998
respiratory failure was lobar atelectasis (25.4%). The NIV failed in 52.4% of patients (33/63) who had a lower pH at 24 hours of treatment (7.35 v 7.42, p ⴝ 0.001) and a higher hospital mortality (51.5% v 6.7%, p ⴝ 0.001) than those in whom NIV was successful. An interval <24 hours from extubation to NIV was a predictive factor for NIV failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.9), whereas obesity was associated with NIV success (odds ratio, 0.22; 95% confidence interval, 0.05-0.91). Conclusions: Reintubation was required in half of the NIVtreated patients and was associated with an increased hospital mortality rate. Early respiratory failure after extubation (<24 hours) is a predictive factor for NIV failure. © 2012 Elsevier Inc. All rights reserved.
A
are and are not likely to benefit from this therapy, thereby improving the indications for its application. The objective of this study was to investigate the use of NIV in the management of respiratory failure after extubation after cardiac surgery, recording the reintubation rate after NIV, and analyzing the factors associated with NIV failure in this patient population.
LMOST ALL CARDIAC SURGICAL patients have some degree of postoperative lung dysfunction. Most have an adequate pulmonary reserve and tolerate this dysfunction well, with minimal effects on oxygenation or breathing. In some patients, however, including those with a history of respiratory disease or with postoperative pneumonia or cardiogenic pulmonary edema, respiratory function can be impaired severely. This deterioration poses a serious problem associated with a longer hospital stay and higher mortality and morbidity. In the early postoperative phase, oxygenation can be impaired by ventilation/perfusion ratio changes and intrapulmonary shunt1; the possible factors include general anesthesia, the receipt of central respiratory depressants, median sternotomy, the presence of drainage tubes, cardiopulmonary bypass, blood-derivative transfusion, diaphragm dysfunction, and comorbidities, especially chronic obstructive pulmonary disease (COPD) and obesity. In recent years, protocols have included the presurgical assessment of the respiratory impairment risk,2,3 and strategies have been developed to decrease pulmonary complications, including the use of early extubation4 or minimally invasive surgery.5 The use of noninvasive ventilation (NIV) in acute respiratory failure has become widespread in recent years, and published data have suggested that it improves oxygenation and can decrease the reintubation rate in medical6 and surgical7,8 patients. NIV is ordered routinely in intensive care units (ICUs), where it has demonstrated its effectiveness to treat acute respiratory failure, especially in patients with COPD,9 acute heart failure,10 and immunodepression.11 It has been used for respiratory failure after extubation in multiple surgical settings, such as abdominal surgery,12 pulmonary resection,13 and cardiac surgery,14 achieving improvements in oxygenation and decreases in the reintubation rate. The authors hypothesized that the mechanisms underlying respiratory failure after cardiac surgery (eg, acute heart failure, pneumonia, and acute respiratory distress syndrome) are similar to those observed in other conditions for which NIV has proved useful. Given the high NIV failure rate in clinical practice, there is a need to identify subgroups of patients who
KEY WORDS: acute respiratory failure, cardiac surgery procedures, noninvasive ventilation, postoperative, reintubation
METHODS This observational study was conducted in a university hospital ICU to which all adult cardiac surgical patients are transferred from the operating room. The hospital has 1,200 beds and serves a population of 450,000 inhabitants, and the ICU has 42 beds and admits about 2,000 patients annually, of whom around 400 are postoperative cardiac surgical patients. Data were gathered retrospectively on patients admitted from September 2006 through September 2009 from the computerized ICU patient database. Data were gathered on demographics (age, sex, body mass index [BMI]), surgical variables (type of surgery, duration of cardiopulmonary bypass), respiratory history (COPD, obstructive sleep apnea syndrome, tobacco consumption, use of domiciliary NIV), causes of postoperative respiratory failure (atelectasis, acute cardiogenic edema, acute lung injury, respiratory pump failure with hypercapnia [partial pressure of arterial carbon dioxide {PaCO2} ⬎45 mmHg], pneumonia, pneumothorax, pleural effusion, or other), durations of mechanical ventilation (MV) (invasive and noninvasive), and spontaneous breathing, gas exchange values, reintubation rate, and hospital mortality. The criterion for NIV application was the onset of acute respiratory failure after initial extubation, defined by ⱖ1 of the following: hypoxemia (oxygen saturation [SaO2] ⬍90% or partial pressure of arterial oxygen ⬍80 mmHg with an inspired oxygen fraction [FIO2] ⬎0.5), respiratory acidosis (pH ⬍7.35 with PaCO2 ⬎45), a respiratory
From the Intensive Care Unit, Hospital Universitario Virgen de las Nieves, Granada, Spain. Address reprint requests to Manuel García-Delgado MD, Intensive Care Unit, Hospital Universitario Virgen de las Nieves, Avenida Fuerzas Armadas, 2, 18014 Granada, Spain. E-mail: mjgardel@ telefonica.net © 2012 Elsevier Inc. All rights reserved. 1053-0770/2603-0016$36.00/0 doi:10.1053/j.jvca.2011.11.007
Journal of Cardiothoracic and Vascular Anesthesia, Vol 26, No 3 (June), 2012: pp 443-447
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Total ICU postsurgical populaon (n=1225) Paents dying under MV
and never extubated (n=62)
Extubated paents
(n=1163) ICU discharge
without new MV (n=1076)
Respiratory failure
considered a success when reintubation was not required and a failure when reintubation and invasive MV were necessary. Arterial blood samples for gas exchange measurements (partial pressure of arterial oxygen, PaCO2, and pH) were drawn at ⬍30 minutes before the mask was placed for NIV and at 4 to 6 and 24 hours after NIV initiation. ABL800-flex analyzers (Radiometer, Copenhagen, Denmark) were used for arterial gas exchange measurements. Qualitative variables were expressed as frequency and percentage and quantitative variables as mean ⫾ standard deviation when the data distribution was normal according to the Kolmogorov-Smirnov test or as median (interquartile range) when it was not. Student’s t and 2 tests were used to compare means of continuous and qualitative variables, respectively, and Student’s test for the related variables to analyze gas exchange variables as a function of time. The nonparametric MannWhitney test was used for variables that were not normally distributed. A logistic regression multivariate model was constructed to identify predictive factors for reintubation. A p value ⬍0.05 was considered statistically significant.
with MV applicaon
RESULTS
(n=87)
Of 1,225 patients admitted to the ICU after cardiac surgery during the 3-year study period, 63 (5.1%) were treated with NIV for respiratory failure after the first extubation (Fig 1). Table 1 presents the baseline characteristics and histories of these patients.
Invasive mechanical venlaon
Noninvasive venlaon
(n=24)
(n=63)
Fig 1. Flow diagram of the study population. MV, mechanical ventilation; ICU, intensive care unit.
Table 1. Baseline Characteristics of Patients Treated With Noninvasive Ventilation (n ⴝ 63) Mean ⫾ SD
rate ⬎25 beats/min, or clinical signs of increased respiratory workload or muscle fatigue (eg, use of accessory muscles, intercostal indrawing, or paradoxic abdominal movement). The criterion for reintubation was an observation of one of the following: cardiac arrest; respiratory arrest; consciousness impairment with an irregular respiratory rate or gasping for air; severe intolerance of NIV; hemodynamic instability (systolic blood pressure ⬍70 mmHg despite adequate volume supply and use of vasopressors, heart rate ⬍50 beats/min); no improvement in hypoxemia (SaO2 ⬍90% despite an increased FIO2), hypercapnia, or decreased pH; no improvement in clinical signs of fatigue; or the inability to clear secretions. The decision to reintubate was made by the treating physician. NIV was withdrawn if all the following conditions were met: the disappearance of the clinical signs of excessive respiratory work and muscle fatigue, a decreased respiratory rate, and improved respiratory acidosis (pH ⬎7.35 and PaCO2 ⬍45 mmHg) and hypoxemia (SaO2 ⱖ92% with FIO2 ⱕ0.5). Bilevel positive airway pressure Vision ventilators (Respironics, Inc, Murrysville, PA) were used, always with oronasal masks. The authors’ ICU has ⬎15 years’ experience with NIV in postoperative and respiratory patients, and all medical/nursing staff can apply this procedure. The initial ventilator support was 4 to 6 cmH2O of expiratory positive airway pressure and 10 to 14 cmH2O of inspiratory positive airway pressure. In patients with persistent hypoxemic respiratory failure (SaO2 ⬍90%), the expiratory positive airway pressure was increased in steps of 2 cmH2O. The minimum FIO2 level required to maintain a SaO2 ⬎92% was used. Patients with hypercapnic respiratory failure (PaCO2 ⬎45 mmHg) required increments of 2 cmH2O in the inspiratory positive airway pressure level to adjust the tidal volume and breathing rate. The procedure was
Age (y) Sex Male Female BMI (kg/m2) ⬎30 ⱕ30 Not recorded Respiratory history COPD Smoking tobacco Domiciliary NIV OSAS Urgent surgery Type of surgery Valve CABG CABG ⫹ valve Others CPB time (min) Causes of respiratory failure Lobar atelectasis Acute cardiogenic edema ALI/ARDS Hypercapnic pump failure Pneumonia Others (pneumothorax, shock)
n (%)
66 ⫾ 11 31 (49.2) 32 (50.8) 31 (49.2) 29 (46.0) 3 (4.8) 7 (11.1) 13 (20.6) 1 (1.6) 1 (1.6) 18 (28.6) 37 (58.7) 10 (15.9) 5 (7.9) 11 (17.5) 138 ⫾ 68 16 (25.4) 15 (23.8) 8 (12.7) 15 (23.8) 5 (7.9) 11 (17.5)
Abbreviations: ALI/ARDS, acute lung injury/acute respiratory distress syndrome; BMI, body mass index; CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; NIV, noninvasive ventilation; OSAS, obstructive sleep apnea syndrome; SD, standard deviation.
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445
Table 2. Differences Between Groups for Success and Failure in Noninvasive Ventilation
Women (%) Urgent surgery (%) Type of surgery (%) Valve CABG CABG ⫹ valve Others Respiratory history (%) COPD Smoking tobacco Domiciliary NIV OSAS Obesity (BMI ⬎30 kg/m2) Cause of respiratory failure (%) Pneumonia ALI/ARDS Acute cardiogenic edema Lobar atelectasis Hypercapnic failure Others Age (y) CPB time (min) Initial MV time (h)
NIV Success (n ⫽ 30)
NIV Failure (n ⫽ 33)
50.0 20.0
51.5 36.4
63.3 20.0 6.7 10.0
54.5 12.1 9.1 24.2
10.0 20.0 3.3 3.3 66.7
12.1 21.2 0.0 0.0 39.4
10.0 10.0 16.7 36.7 16.7 20.0 65 ⫾ 12 128 ⫾ 90 115 ⫾ 174
6.1 15.2 15.2 15.2 30.3 36.0 67 ⫾ 9 113 ⫾ 67 145 ⫾ 167
p Value
NS NS NS
NS
7.40 ⫾ 0.08; p ⫽ 0.03) and 24 hours (7.38 ⫾ 0.08 v 7.42 ⫾ 0.05; p ⫽ 0.006). In the group requiring reintubation, no significant changes versus baseline were observed at either time point. After 24 hours of NIV, the pH was significantly lower in the patients who required intubation than in those who did not (7.35 ⫾ 0.06 v 7.42 ⫾ 0.05; p ⫽ 0.001). In the multivariate regression analysis, a duration of spontaneous breathing (from extubation to NIV application) ⬍24 hours emerged as a predictive factor for NIV failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.9; p ⫽ 0.02), whereas obesity (BMI ⬎30 kg/m2) was found to be a predictive factor for NIV success (odds ratio, 0.22; 95% confidence interval, 0.05-0.91; p ⫽ 0.03). DISCUSSION
NS
NS NS NS
Abbreviations: ALI/ARDS, acute lung injury/acute respiratory distress syndrome; BMI, body mass index; CABG, coronary artery bypass grafting; COPD, chronic obstructive pulmonary disease; CPB, cardiopulmonary bypass; MV, mechanical ventilation; NIV, noninvasive ventilation; NS, not significant; OSAS, obstructive sleep apnea syndrome.
In the postoperative unit, the median duration of the initial MV (from surgery to extubation) was 8 hours (range, 5-24 hours) for all patients. In contrast, the median time of the initial MV was 38 hours (range, 8-211 hours) and the duration of spontaneous breathing (from extubation to NIV application) was 40 hours (range, 18-96 hours) in this subgroup of 63 patients. The global hospital mortality rate in this subgroup was 30.2% (n ⫽ 19). Reintubation was required by 33 patients, for an NIV failure rate of 52.4%; the hospital mortality was significantly higher (51.5% v 6.7%, p ⫽ 0.001) and the duration of NIV therapy was nonsignificantly longer (44 hours, 10-75 hours, v 22 hours, 10-58 hours; p ⫽ 0.51) in these patients (NIV failures) than in those who did not require reintubation (NIV successes). There was a higher frequency of a BMI ⬎30 kg/m2 (66.7% v 39.4%; p ⫽ 0.03) and a larger percentage of patients with lobar atelectasis as the cause of respiratory failure (36.7% v 15.2%; p ⫽ 0.049) among the NIV successes than among the NIV failures. No significant intergroup differences were found for the remaining clinical variables (Table 2). There were no intergroup differences in gas exchange data before NIV therapy (Table 3, Fig 2). In the group not requiring reintubation, an improvement in oxygenation (partial pressure of arterial oxygen/FIO2) versus baseline was observed at 6 hours (154 ⫾ 88 v 207 ⫾ 100; p ⫽ 0.01) and 24 hours (154 ⫾ 88 v 213 ⫾ 92; p ⫽ 0.01) of NIV, and an improvement in pH was recorded at 6 hours (7.38 ⫾ 0.08 v
The main findings of the present study were that reintubation was necessary for around 50% of postoperative cardiac surgical patients treated with NIV for respiratory failure after extubation and that NIV failure was associated with an increased mortality rate. The early onset (⬍24 hours) of respiratory failure after extubation was associated with NIV failure, and obesity was associated with NIV success. Reported NIV failure rates vary and depend on multiple factors, such as the experience of the medical teams, the type of patient population, the severity of the illness, and the timing of NIV application (before or after the onset of respiratory failure). NIV has shown greater benefits in medical patients with COPD or cardiogenic pulmonary edema, with low intubation rates of around 15% in most cases.15,16 There has been greater variability in respiratory failure after extubation, with reports of NIV failure rates ranging from 10% to 72%.17-20 In one study of patients in a postoperative recovery room after elective surgery (only 7.5% of cardiovascular surgeries), none of the 83 patients treated with NIV required reintubation.21 The cardiorespiratory status of postoperative cardiac surgical patients is less stable and is aggravated by the effects of cardiopulmonary bypass on the ventilation/perfusion ratio and extravascular lung water. The duration of initial MV (38 hours) was much longer in the present subgroup of patients re-
Table 3. Gas Exchange Values in Groups of Success and Failure of Noninvasive Ventilation
PaO2/FIO2 before NIV PaCO2 before NIV pH before NIV PaO2/FIO2 at 6 hours PaCO2 at 6 hours pH at 6 hours PaO2/FIO2 at 24 hours PaCO2 at 24 hours pH at 24 hours
NIV Success
NIV Failure
p Value
154 ⫾ 88 46 ⫾ 15 7.38 ⫾ 0.08 207 ⫾ 100* 44 ⫾ 13 7.40 ⫾ 0.08† 213 ⫾ 92* 42 ⫾ 10 7.42 ⫾ 0.05‡
149 ⫾ 47 45 ⫾ 9 7.36 ⫾ 0.08 186 ⫾ 81 43 ⫾ 9 7.36 ⫾ 0.08 187 ⫾ 66 44 ⫾ 9 7.35 ⫾ 0.06
NS NS NS NS NS NS NS NS 0.001
NOTE. At 6 hours, n ⫽ 29 in the NIV success group and n ⫽ 30 in the NIV failure group; at 24 hours, n ⫽ 28 in the NIV success group and n ⫽ 22 in the NIV failure group. Abbreviations: FIO2, fraction of inspired oxygen; NIV, noninvasive ventilation; NS, not significant; PaCO2, partial pressure of arterial carbon dioxide; PaO2, partial pressure of arterial oxygen. *p ⫽ 0.01, †p ⫽ 0.03, ‡p ⫽ 0.006 versus value before NIV.
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PaO2 / FiO2
250
*
200
*
150 100 50
Pa CO2 (mmHg)
60 50 40
30 20 7,5
8
7,45
pH
# 7,4 7,35 7,3
Pre-NIV
6h
24 h
Fig 2. Gas exchange values in the NIV success (solid line) and NIV failure (dashed line) groups plotted against time. Mean values are shown. FIO2, fraction of inspired oxygen; NIV, noninvasive ventilation; PaCO2, partial pressure of arterial carbon dioxide; PaO2, partial pressure of arterial oxygen. * p ⴝ 0.01, # p ⴝ 0.03 and ⴥ p ⴝ 0.006 versus value before NIV.
quiring NIV than usually observed in the authors’ unit, where extubation is expected to take place in the first 8 to 12 hours. This finding indicates the higher frequency of postoperative complications in these patients, their more severe and unstable condition, and the greater possibility of NIV failure. Prolonged postoperative MV has been associated with higher rates of acute respiratory failure in cardiac surgical patients.22 Obesity is considered a risk factor for respiratory complications.23 Postoperative respiratory failure is increased in obese patients by their supine position during prolonged surgery, greater propensity to alveolar collapse and obstructive sleep apnea syndrome, and higher sensitivity to the respiratory depressive effect of sedating drugs and opiates.24 The benefits of NIV in obese patients are well documented. Joris et al12 reported that NIV increased the peak expiratory flow rate, forced vital capacity, and SaO2 on the first day after gastroplasty. El-Solh et al20 applied NIV immediately after extubation in severely obese patients (BMI ⱖ35 kg/m2) and found a decrease
in the respiratory failure rate and a tendency to a lower hospital mortality rate in the subgroup of patients with hypercapnia, which were attributable to increased lung volumes and lower atelectasis decreasing rates. The timing of postoperative NIV treatment is an important issue in evaluating its clinical effectiveness. Some clinical trials have found that the application of NIV therapy after the onset of respiratory failure produces no improvement in reintubation or mortality. Keenan et al19 studied a heterogenous group of (noncardiac surgical) patients who developed respiratory failure ⬍48 hours after extubation and found no difference in reintubation rates (69% v 72%; p ⫽ 0.79), hospital mortality, MV duration, or hospital stay between patients selected randomly for NIV treatment or standard therapy (supplemental oxygen, aggressive physiotherapy, and pharmacotherapy). A larger, multicenter study reported a similar reintubation rate (48%) between NIV-treated patients and those receiving standard treatment but found a higher ICU mortality rate in the former (25% v 14%; p ⫽ 0.048).18 However, the outcomes were superior when NIV was applied immediately after extubation, before the onset of respiratory failure. In a study of patients at high risk of respiratory failure after extubation,25 lower reintubation (8.3% v 24.4%; p ⫽ 0.02) and mortality (⫺10%; p ⬍ 0.01) rates were found in patients treated with NIV immediately after extubation than in those receiving standard medical treatment. Likewise, in a heterogenous group of mostly medical patients,26 the early use of NIV decreased the rates of respiratory failure after extubation (16% v 33%; p ⫽ 0.02) and ICU mortality (3% v 14%; p ⫽ 0.01), especially in patients with hypercapnia. Hypercapnic patients and those with chronic respiratory disease especially benefited from NIV therapy immediately after extubation.27,28 Although NIV was less effective in patients who required NIV earlier in the present study, this does not imply that its early application after extubation is less effective, but rather that NIV failure is more frequent when the respiratory failure occurs within 24 hours of extubation. This can be considered an extubation failure, which is associated with a persistence of the causes of respiratory failure or polyneuropathy, among other conditions. Studies have demonstrated that the prophylactic use of nasal continuous positive airway pressure improves oxygenation in postoperative cardiac surgical patients compared with conventional oxygen therapy14 and decreases the incidence of pneumonia, reintubation, and ICU readmission.29 In a recent study, the application of NIV in cardiac surgical patients developing hypoxemic respiratory failure improved their oxygenation and decreased the incidence of lung infections compared with patients with acute respiratory failure requiring immediate reintubation.30 The NIV failure rate was 22% to 25%, lower than in the present series, but the NIV application produced more complications related to the sternal wound compared with patients who received MV immediately. The limitations of the present study included its retrospective nature and the possible bias involved in gathering information from databases. For instance, the frequency of obstructive sleep apnea syndrome usually is underestimated in retrospective studies.20 There was a large proportion of hypercapnic respiratory failure in the present series, which likely was caused by the
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late application of NIV in hypoxemic respiratory failure rather than by the patients’ respiratory history, which may have contributed to the high reintubation rate found. A delay in reversing respiratory failure is associated with worse outcomes,31 and this is valid for the period before NIV (respiratory distress) and the period with NIV (in patients not treated effectively). In the present patients, NIV failure was associated with a longer duration of NIV treatment, and some patients possibly should have been reintubated earlier. The lack of randomized trials means that conclusions cannot be drawn on the effectiveness of NIV to avoid reintubation in
cardiac surgical patients with postoperative respiratory failure,8 but it appears useful in certain patient groups, such as the obese, and when applied at the appropriate time. Perhaps patients with respiratory failure soon after extubation (⬍24 hours) should be reintubated because of the high likelihood of NIV failure. ACKNOWLEDGMENTS The authors are grateful to Richard Davies for assistance with the English version of this report.
REFERENCES 1. Ng CS, Wan S, Yim AP, et al: Pulmonary dysfunction after cardiac surgery. Chest 121:1269-1277, 2002 2. Légaré JF, Hirsch GM, Buth KJ, et al: Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting. Eur J Cardiothorac Surg 20:930-936, 2001 3. Filsoufi F, Rahmanian PB, Castillo JG, et al: Predictors and early and late outcomes of respiratory failure in contemporary cardiac surgery. Chest 133:713-721, 2008 4. Meade MO, Guyatt G, Butler R, et al: Trials comparing early vs late extubation following cardiovascular surgery. Chest 120:445S453S, 2001 5. Foghsgaard S, Gazi D, Bach K, et al: Minimally invasive aortic valve replacement reduces atelectasis in cardiac intensive care. Acute Card Care 11:169-172, 2009 6. Honrubia T, García López FJ, Franco N, et al: Noninvasive vs conventional mechanical ventilation in acute respiratory failure: A multicenter, randomized controlled trial. Chest 128:3916-3924, 2005 7. Squadrone V, Coha M, Cerutti E, et al: Continuous positive airway pressure for treatment of postoperative hypoxemia: A randomized controlled trial. JAMA 293:589-595, 2005 8. Chiumello D, Chevallard G, Gregoretti C: Non-invasive ventilation in postoperative patients: A systematic review. Intensive Care Med 37:918-929, 2011 9. Lightowler JV, Wedzicha JA, Elliott MW, et al: Non-invasive positive pressure ventilation to treat respiratory failure resulting from exacerbations of chronic obstructive pulmonary disease: Cochrane systematic review and meta-analysis. BMJ 326:185-189, 2003 10. Masip J, Roque M, Sánchez B, et al: Noninvasive ventilation in acute cardiogenic pulmonary edema: Systematic review and metaanalysis. JAMA 294:3124-3130, 2005 11. Hilbert G, Gruson D, Vargas F, et al: Noninvasive ventilation in immunosuppressed patients with pulmonary infiltrates, fever, and acute respiratory failure. N Engl J Med 344:481-487, 2001 12. Joris JL, Sottiaux TM, Chiche JD, et al: Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on the postoperative pulmonary restrictive syndrome in obese patients undergoing gastroplasty. Chest 111:665-670, 1997 13. Auriant I, Jallot A, Hervé P, et al: Noninvasive ventilation reduces mortality in acute respiratory failure following lung resection. Am J Respir Crit Care Med 164:1231-1235, 2001 14. Lopes CR, Brandao CMA, Nozawa E, et al: Benefits of noninvasive ventilation after extubation in the postoperative period of heart surgery. Rev Bras Cir Cardiovasc 23:344-350, 2008 15. Plant PK, Owen JL, Elliott MW: Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: A multicentre randomised controlled trial. Lancet 355:1931-1935, 2000 16. Masip J, Betbesé AJ, Páez J, et al: Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardio-
genic pulmonary oedema: A randomised trial. Lancet 356:2126-2132, 2000 17. Badiger R, Green M, Hackwood H, et al: Non-invasive ventilation in surgical patients in a district general hospital. J Anesth 59:967-970, 2004 18. Esteban A, Frutos-Vivar F, Ferguson ND, et al: Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med 350:2452-2460, 2004 19. Keenan SP, Powers C, McCormack DG, et al: Noninvasive positive-pressure ventilation for postextubation respiratory distress: A randomized controlled trial. JAMA 287:3238-3244, 2002 20. El-Solh AA, Aquilina A, Pineda L, et al: Noninvasive ventilation for prevention of post-extubation respiratory failure in obese patients. Eur Respir J 28:588-595, 2006 21. Battisti A, Michotte JB, Tassaux D, et al: Non-invasive ventilation in the recovery room for postoperative respiratory failure: A feasibility study. Swiss Med Wkly 135:339-343, 2005 22. Kilger E, Möhnle P, Nassau K, et al: Noninvasive mechanical ventilation in patients with acute respiratory failure after cardiac surgery. Heart Surg Forum 13:E91-E95, 2010 23. Akinnusi ME, Pineda LA, El Solh AA: Effect of obesity on intensive care morbidity and mortality: A meta-analysis. Crit Care Med 36:151-158, 2008 24. Benumof JL: Obstructive sleep apnea in the adult obese patient: Implications for airway management. J Clin Anesth 13:144-156, 2001 25. Nava S, Gregoretti C, Fanfulla F, et al: Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med 33:2465-2470, 2005 26. Ferrer M, Valencia M, Nicolas JM, et al: Early noninvasive ventilation averts extubation failure in patients at risk: A randomized trial. Am J Respir Crit Care Med 173:164-170, 2006 27. Ferrer M, Sellarés J, Valencia M, et al: Non-invasive ventilation after extubation in hypercapnic patients with chronic respiratory disorders: Randomised controlled trial. Lancet 374:1082-1088, 2009 28. Hilbert G, Gruson D, Portel L, et al: Noninvasive pressure support ventilation in COPD patients with postextubation hypercapnic respiratory insufficiency. Eur Respir J 11:1349-1353, 1998 29. Zarbock A, Mueller E, Netzer S, et al: Prophylactic nasal continuous positive airway pressure following cardiac surgery protects from postoperative pulmonary complications: A prospective, randomized, controlled trial in 500 patients. Chest 135:1252-1259, 2009 30. Boeken U, Schurr P, Kurt M, et al: Early reintubation after cardiac operations: Impact of nasal continuous positive airway pressure (nCPAP) and noninvasive positive pressure ventilation (NPPV). J Thorac Cardiovasc Surg 58:398-402, 2010 31. Epstein SK, Ciobotaru RL: Independent effects of etiology of failure and time of reintubation on outcome for patients failing extubation. Am J Respir Crit Care Med 4:161-165, 1998