Chronic obstructive pulmonary disease * 9: management of ventilatory failure in COPD

Hypercapnic COPD patients and NIV at home: is there any benefit? Using the CAT and BODE index in an effort to prove benefits of NIV in these patients

Introduction

The benefits of long-term noninvasive ventilation (NIV) in stable COPD with chronic hypercapnic respiratory failure (CHRF) have been debated for many years due to the conflicting results observed in these patients.

Materials and methods

We investigated the effects of domiciliary NIV in stable hypercapnic COPD patients for a period of 1 year using COPD Assessment Test (CAT), BODE Index, and the number of acute exacerbations. NIV was administered in 57 stable COPD patients with CHRF in the spontaneous/timed mode. Spirometry, 6 minute walk test, Medical Research Council dyspnea scale, arterial blood gases, number of acute exacerbations, BODE Index, and CAT were assessed. Study participants were reassessed in the 1st, 6th, and 12th months after the initial evaluation.

Results

There was a significant improvement in COPD exacerbations (p<0.001), CAT (p<0.001), PO₂ (p<0.001), PCO₂ (p<0.001), and Medical Research Council dyspnea scale (p<0.001) in 1 year of follow-up. BODE Index was improved in the first 6 months (5.8±2.2 vs 4.8±2.4, p<0.001), but the improvement was not maintained.

Conclusion

In conclusion, domiciliary NIV in stable COPD patients with CHRF has beneficial effect on CAT, arterial blood gases, and number of acute exacerbations in a year of NIV use at home. A significant improvement in BODE Index from baseline to 12 months was found in patients aged >70 years, while for those aged <70, the improvement was not maintained after the sixth month.

Effects of neurally adjusted ventilatory assist on air distribution and dead space in patients with acute exacerbation of chronic obstructive pulmonary disease

Background

Neurally adjusted ventilatory assist (NAVA) could improve patient-ventilator interaction; its effects on ventilation distribution and dead space are still unknown. The aim of this study was to evaluate the effects of varying levels of assist during NAVA and pressure support ventilation (PSV) on ventilation distribution and dead space in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Methods

Fifteen mechanically ventilated patients with AECOPD were included in the study. The initial PSV levels were set to 10 cmH₂O for 10 min. Thereafter, the ventilator mode was changed to NAVA for another 10 min with the same electrical activity of the diaphragm as during PSV. Furthermore, the ventilation mode was switched between PSV and NAVA every 10 min in the following order: PSV 5 cmH₂O; NAVA 50%; PSV 15 cmH₂O; and NAVA 150% (relative to the initial NAVA support level). Ventilation distribution in the lung was evaluated in percentages in regions of interest (ROI) of four anteroposterior segments of equal height (ROI1 to ROI4 represents ventral, mid-ventral, mid-dorsal, and dorsal, respectively). Blood gases, ventilation distribution (electrical impedance tomography), diaphragm activity (B-mode ultrasonography), and dead space fraction (PeCO₂ and PaCO₂) were measured.

Results

The trigger and cycle delays were lower during NAVA than during PSV. The work of trigger was significantly lower during NAVA compared to PSV. The diaphragm activities based on ultrasonography were higher during NAVA compared to the same support level during PSV. The ventilation distribution in ROI4 increased significantly (P < 0.05) during NAVA compared to PSV (except for a support level of 50%). Similar results were found in ROI3 + 4. NAVA reduced dead space fraction compared to the corresponding support level of PSV.

Conclusions

NAVA was superior to PSV in AECOPD for increasing ventilation distribution in ROI4 and reducing dead space.

Trial registration

Clinicaltrials.gov, NCT02289573. Registered on 12 November 2014.

Comparison of global initiative for chronic obstructive pulmonary disease 2013 classification and body mass index, airflow obstruction, dyspnea, and exacerbations index in predicting mortality and exacerbations in elderly adults with chronic obstructive pulmonary disease

OBJECTIVES

To examine whether the Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) 2013 revision offers greater predictive ability than the body mass index, airflow obstruction, dyspnea, and exacerbations (BODEx) index in elderly adults with chronic obstructive pulmonary disease (COPD).

DESIGN

Prospective cohort study.

SETTING

University-affiliated medical center.

PARTICIPANTS

Taiwanese outpatients with COPD (N = 354).

MEASUREMENTS

Participants were classified as Group A (low risk with mild dyspnea), Group B (low risk with more-severe dyspnea), Group C (high risk with mild dyspnea), and Group D (high risk with more-severe dyspnea) for GOLD 2013 and from Quartile 1 (0-2 points) to 4 (7-9 points) for BODEx score. Ability to predict exacerbations and mortality was compared using logistic regression analysis with receiver operating characteristic (ROC) curve estimations and area under the ROC curve (AUC).

RESULTS

Mortality was 14.1% for GOLD Group A, 14.5% for Group B, 6.5% for Group C, and 35.8% for Group D and 15.2% for BODEx Quartile 1, 22.5% for Quartile 2, 28.1% for Quartile 3, and 79.2% for Quartile 4. Risk of exacerbation relative to Group A was 1.7 (95% confidence interval (CI) = 0.6-4.3) for Group B, 14.1 (95% CI = 4.6-43.2) for Group C, and 17.9 (95% CI = 7.6-42.0) for Group D. The AUC for the GOLD classification and BODEx index were 0.65 and 0.67 for mortality (P = .60) and 0.79 and 0.73 for exacerbation (P = .03).

CONCLUSION

The GOLD 2013 classification performed well in identifying individuals at risk of exacerbations, and its predictive ability for exacerbations was better than that of the BODEx index, although the predictive ability for mortality in elderly adults with COPD was poor for both indices.

End-tidal arterial CO2 partial pressure gradient in patients with severe hypercapnia undergoing noninvasive ventilation

BACKGROUND

Patients with severe hypercapnia represent a particularly serious condition in an emergency department (ED), requiring immediate attention. Noninvasive ventilation (NIV) is an integral part of the treatment for acute respiratory failure. The present study aimed to validate the measurement of end-tidal CO2 (EtCO2) as a noninvasive technique to evaluate the effectiveness of NIV in acute hypercapnic respiratory failure.

METHODS

Twenty consecutive patients admitted to the ED with severe dyspnea were enrolled in the study. NIV by means of bilevel positive airway pressure, was applied to the patients simultaneously with standard medical therapy and continued for 12 hours; the arterial blood gases and side-stream nasal/oral EtCO2 were measured at subsequent times: T0 (admission to the ED), T1h (after 1 hour), T6h (after 6 hours), and T12h (after 12 hours) during NIV treatment.

RESULTS

The arterial CO2 partial pressure (PaCO2)-EtCO2 gradient decreased progressively, reaching at T6h and T12h values lower than baseline (P < 0.001), while arterial pH increased during the observation period (P < 0.001). A positive correlation was found between EtCO2 and PaCO2 values (r = 0.89, P < 0.001) at the end of the observation period.

CONCLUSION

In our hypercapnic patients, the effectiveness of the NIV was evidenced by the progressive reduction of the PaCO2-EtCO2 gradient. The measurement of the CO2 gradient could be a reliable method in monitoring the effectiveness of NIV in acute hypercapnic respiratory failure in the ED.

[Non-invasive mechanical ventilation in COPD]

Non-invasive mechanical ventilation is the preferred method for the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). Primary contraindications and stopping criteria must be regarded to avoid delaying endotracheal intubation. The primary interface is usually a nasal-oral mask. Cautious sedation can facilitate non-invasive ventilation in some patients. Under certain circumstances non-invasive ventilation may enable successful extubation in COPD patients with prolonged weaning. COPD patients can also benefit from preventive non-invasive ventilation in order to avoid re-intubation after a planned extubation. Domiciliary nocturnal non-invasive ventilation is an option for some patients with COPD in chronic hypercapnic respiratory failure. This treatment should be established in a specialised unit.

Acid-base disorders in patients with chronic obstructive pulmonary disease: a pathophysiological review

The authors describe the pathophysiological mechanisms leading to development of acidosis in patients with chronic obstructive pulmonary disease and its deleterious effects on outcome and mortality rate. Renal compensatory adjustments consequent to acidosis are also described in detail with emphasis on differences between acute and chronic respiratory acidosis. Mixed acid-base disturbances due to comorbidity and side effects of some drugs in these patients are also examined, and practical considerations for a correct diagnosis are provided.

The effects of long-term noninvasive ventilation in hypercapnic COPD patients: a randomized controlled pilot study

Introduction

Noninvasive ventilation (NIV) is a well-established treatment for acute-on- chronic respiratory failure in hypercapnic COPD patients. Less is known about the effects of a long-term treatment with NIV in hypercapnic COPD patients and about the factors that may predict response in terms of improved oxygenation and lowered CO₂ retention.

Methods

In this study, we randomized 15 patients to a routine pharmacological treatment (n = 5, age 66 [standard deviation ± 6] years, FEV₁ 30.5 [±5.1] %pred, PaO₂ 65 [±6] mmHg, PaCO₂ 52.4 [±6.0] mmHg) or to a routine treatment and NIV (using the Synchrony BiPAP device [Respironics, Inc, Murrsville, PA]) (n = 10, age 65 [±7] years, FEV₁ 29.5 [±9.0] %pred, PaO₂ 59 [±13] mmHg, PaCO₂ 55.4 [±7.7] mmHg) for 6 months. We looked at arterial blood gasses, lung function parameters and performed a low-dose computed tomography of the thorax, which was later used for segmentation (providing lobe and airway volumes, iVlobe and iVaw) and post-processing with computer methods (providing airway resistance, iRaw) giving overall a functional image of the separate airways and lobes.

Results

In both groups there was a nonsignificant change in FEV₁ (NIV group 29.5 [9.0] to 38.5 [14.6] %pred, control group 30.5 [5.1] to 36.8 [8.7] mmHg). PaCO₂ dropped significantly only in the NIV group (NIV: 55.4 [7.7] → 44.5 [4.70], P = 0.0076; control: 52.4 [6.0] → 47.6 [8.2], NS). Patients actively treated with NIV developed a more inhomogeneous redistribution of mass flow than control patients. Subsequent analysis indicated that in NIV-treated patients that improve their blood gases, mass flow was also redistributed towards areas with higher vessel density and less emphysema, indicating that flow was redistributed towards areas with better perfusion. There was a highly significant correlation between the % increase in mass flow towards lobes with a blood vessel density of >9% and the increase in PaO₂. Improved ventilation–perfusion match and recruitment of previously occluded small airways can explain the improvement in blood gases.

Conclusion

We can conclude that in hypercapnic COPD patients treated with long-term NIV over 6 months, a mass flow redistribution occurs, providing a better ventilation–perfusion match and hence better blood gases and lung function. Control patients improve homogeneously in iVaw and iRaw, without improvement in gas exchange since there is no improved ventilation/perfusion ratio or increased alveolar ventilation. These differences in response can be detected through functional imaging, which gives a more detailed report on regional lung volumes and resistances than classical lung function tests do. Possibly only patients with localized small airway disease are good candidates for long-term NIV treatment. To confirm this and to see if better arterial blood gases also lead to better health related quality of life and longer survival, we have to study a larger population.

Treatment of respiratory failure in COPD

Patients with advanced COPD and acute or chronic respiratory failure are at high risk for death. Beyond pharmacological treatment, supplemental oxygen and mechanical ventilation are major treatment options. This review describes the physiological concepts underlying respiratory failure and its therapy, as well as important treatment outcomes. The rationale for the controlled supply of oxygen in acute hypoxic respiratory failure is undisputed. There is also a clear survival benefit from long-term oxygen therapy in patients with chronic hypoxia, while in mild, nocturnal, or exercise-induced hypoxemia such long-term benefits appear questionable. Furthermore, much evidence supports the use of non-invasive positive pressure ventilation in acute hypercapnic respiratory failure. It application reduces intubation and mortality rates, and the duration of intensive care unit or hospital stays, particularly in the presence of mild to moderate respiratory acidosis. COPD with chronic hypercapnic respiratory failure became a major indication for domiciliary mechanical ventilation, based on pathophysiological reasoning and on data regarding symptoms and quality of life. Still, however, its relevance for long-term survival has to be substantiated in prospective controlled studies. Such studies might preferentially recruit patients with repeated hypercapnic decompensation or a high risk for death, while ensuring effective ventilation and the patients’ adherence to therapy.

Current status of noninvasive ventilation in stable COPD patients

Noninvasive ventilation (NIV) has been one of the major advances in respiratory medicine in the last decade. NIV improves quality of life, prolongs survival, and improves gas exchange and sleep quality in restrictive patients, but evidence available now does not allow us to establish clear criteria for prescribing NIV in patients with chronic respiratory failure due to COPD. On the basis of the available studies, NIV should not be used as a treatment of choice for all patients with COPD, even when disease is severe. However, there is more evidence that NIV has an important effect in these patients. In fact, a selected group of patients may well benefit from domiciliary mechanical ventilation, and we need to be able to identify who they are. Moreover, NIV can be a new strategy to improve exercise tolerance in COPD patients.

Non-invasive ventilation in exacerbations of COPD

Randomized controlled trials have confirmed the evidence and helped to define when and where non invasive mechanical ventilation (NIV) should be the first line treatment of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Noninvasive ventilation has its best indication in moderate-to-severe respiratory acidosis in patients with AECOPD. For this indication, studies conducted in ICU, in wards and in accident and emergency departments confirmed its effectiveness in preventing endotracheal intubation and reducing mortality. The skill of the health care team promotes proper NIV utilization and improves the patient outcome. Patients with severe acidosis or with altered levels of consciousness due to hypercapnic acute respiratory failure are exposed to high risk of NIV failure. In these patients a NIV trial may be attempted in closely monitored clinical settings where prompt endotracheal intubation may be assured.

Non-invasive ventilation in chronic hypercapnic COPD patients with exacerbation and a pH of 7.35 or higher

BACKGROUND

Current guidelines suggest the use of non-invasive ventilation (NIV) in hypercapnic chronic obstructive pulmonary disease (COPD) exacerbations in patients presenting with a pH of 7.25-7.35. The aim of this study was to investigate the role of NIV in COPD patients with chronic hypercapnic respiratory failure admitted to the hospital with acute exacerbations and an arterial pH of 7.35 or higher.

METHODS

Forty-seven COPD patients with chronic hypercapnic respiratory failure admitted for exacerbations and with a pH of 7.35 or higher were randomized to receive standard medical therapy (control group) or medical therapy plus NIV (NIV group). Arterial blood gases were measured at baseline, after 1 h, 6 h, 12 h, 24 h, 48 h, and at discharge. Need for admission to intensive care unit (ICU), death, and duration of hospitalization were recorded. The final analysis included 42 patients (21 controls and 21 NIV patients).

RESULTS

NIV resulted in a shorter hospital stay (5.5+/-2.6 vs 10.1+/-4.4 days for controls, p=0.0004). Two patients from the control group were admitted to the ICU and one eventually died, whereas all NIV patients were successfully discharged. The NIV group showed a faster improvement in PaCO(2) and pH. At discharge, the NIV group had a lower PaCO(2) (6.5+/-0.6 kPa vs 7.5+/-1.1 kPa, p=0.01) but a comparable pH (7.43+/-0.03 vs 7.43+/-0.04, p=0.93). PaO(2) and PaO(2)/FiO(2) levels showed similar improvement in both groups at discharge.

CONCLUSION

Early administration of NIV in COPD patients with chronic hypercapnic respiratory failure admitted for acute exacerbations with a pH of 7.35 or higher results in a reduced hospital stay and faster improvement of arterial blood gases.

Devenir des patients BPCO traités par ventilation non invasive prolongée à domicile

BACKGROUND

The use of domiciliary non-invasive positive pressure ventilation (NIPPV) is still controversial in stable hypercapnic COPD.

METHODS

Records of COPD patients who received home NIPPV from 1990 to 2002 either following an acute exacerbation or because of stable hypercapnia were retrospectively reviewed.

RESULTS

Thirty-seven patients receiving long term oxygen therapy for 50 +/- 47 months were included. At inclusion, their mean +/- SD: FEV1 was 27 +/- 9% predicted, inspiratory capacity was 45 +/- 14% predicted, PaO2 breathing room air was 50 +/- 10 mm Hg, PaCO2 breathing room air = 53 +/- 8 mm Hg, PaCO2 with oxygen was 60 +/- 9 mm Hg. Median survival with NIPPV was 41 months. The 1-year, 3-year and 5-year survival rates with NIPPV were 92%, 62% and 24% respectively. Twelve months after onset of home NIPPV, PaCO2 breathing room air and with oxygen were significantly lower (47 +/- 8 mm Hg, p = 0.028 and 53 +/- 8 mm Hg, p = 0.005, respectively), inspiratory capacity was significantly improved (54 +/- 18% predicted, p = 0.033).

CONCLUSION

This study suggests that home NIPPV allows a lasting physiological stabilization in selected COPD patients, particularly those with an advanced disease, by reducing hypercapnia and improving inspiratory capacity.

The pathophysiology of emphysema: considerations for critical care nursing practice

Emphysema is caused by exposure to cigarette smoking as well as alpha(1)-antitrypsin deficiency. It has been estimated to cost the National Health Service (NHS) in excess of 800 million pounds per year in related health care costs. The challenges for Critical Care nurses are those associated with dynamic hyperinflation, Auto-PEEP, malnutrition and the weaning from invasive and non-invasive mechanical ventilation. In this paper we consider the impact of the pathophysiology of emphysema, its effects on other body systems as well as the impact acute exacerbations have when patients are admitted to the Intensive Care Unit.

The use of noninvasive mechanical ventilation in COPD with severe hypercapnic acidosis

STUDY OBJECTIVES

To compare the effect of noninvasive mechanical ventilation (NIV) in severely acidotic with mildly acidotic patients with acute hypercapnic chronic obstructive lung disease (COPD).

DESIGN

Comparison of NIV in consecutively enrolled patients with acute hypercapnic COPD with mild (pH 7.25-7.35) or severe (pH<7.25) acidosis on time to normalise pH and improve PaCO(2), duration of NIV treatment, length of stay in hospital and survival. Results (meadian (IQR)): Twenty-nine patients had 36 episodes of acute hypercapnic respiratory failure: Seventeen with pH<7.25 and 19 with pH 7.25-7.34. Compared with the mildly acidotic group, the severely acidotic group took a similar length of time for pH to normalise and PaCO(2) improve (12 (6-34) vs 12 (4-28)h, respectively, P=0.42), with similar duration of NIV treatment (60 (35-96) vs 68 (36-48)h, respectively, P=0.25) and hospital length of stay (8 (7-18) vs 9 (5-17) days, respectively, P=0.61). Overall survival was 89%, with 95% in the mild and 82% in the severely acidotic groups.

CONCLUSIONS

Noninvasive ventilation is effective in the treatment of patients with severe acidosis due to acute hypercapnic COPD.

Evaluation of a pumping assist lung that uses a rotating fiber bundle

A paracorporeal respiratory assist lung (PRAL) is being developed for supplemental gas exchange to allow the native lungs of acute lung failure patients to heal. The device consists of a rotating annular microporous hollow fiber membrane bundle. The rotation augments the gas exchange efficiency of the device at constant flow-rate thereby uncoupling gas exchange and flow rate. The rotating fibers also enable the PRAL to pump the blood without the need for an additional pump or arterial cannulation. Blood flow rates will be between 500 and 750 ml/min with CO(2) removal rates of 100-130 ml/min. A prototype was manufactured with an overall surface area of 0.25 m. When rotated at 1500 rpm, CO(2) removal increased by 133% and O(2) transfer increased by 157% during an in vitro bovine blood study. The pumping of the rotating fiber bundle was assessed in a glycerol/water solution. At 1500 rpm, the PRAL generated 750 ml/min against 52 mm Hg pressure. Hemolysis of the device was assessed using in vitro bovine blood from a slaughterhouse. Plasma free hemoglobin levels were similar regardless of whether the rotating fibers were present in the PRAL, indicating that a rotating fiber bundle can be used to increase gas exchange without causing blood trauma.

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

OBJECTIVE

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

DESIGN AND SETTING

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

PATIENTS AND PARTICIPANTS

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

MEASUREMENTS AND RESULTS

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

CONCLUSIONS

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

Management of severe COPD

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide, and the burden of the disorder will continue to increase over the next 20 years despite medical intervention. Apart from smoking cessation, no approach or agent affects the rate of decline in lung function and progression of the disease. Especially in the later phase, COPD is a multicomponent disorder, and various integrated intervention strategies are needed as part of the optimum management programme. This seminar describes largely non-pharmacological interventions aimed at improving health status and function of disabled patients. Exacerbations become progressively more troublesome as baseline lung function declines, commonly necessitating hospital admission and associated with the development of acute respiratory failure.

Active cycle of breathing techniques in non-invasive ventilation for acute hypercapnic respiratory failure

We hypothesised that applying the active cycle of breathing techniques (ACBT) in patients with acute hypercapnic respiratory failure undergoing non-invasive ventilation would improve patient outcome. Thirty-four patients were randomised so that 17 patients with acute hypercapnic respiratory failure received the ACBT and non-invasive ventilation (ACBT group), and 17 patients received non-invasive ventilation alone (control group). The primary outcome measure was length of time requiring non-invasive ventilation, and secondary outcome measures were change in acute physiology score, change in arterial blood gas values, total duration of non-invasive ventilation, and length of stay in the intensive care unit. Although not significant, there was a greater decrease in arterial carbon dioxide pressure in the ACBT group compared to the control group (-21.41 mmHg vs -17.45 mmHg, p = 0.27). Total duration of ventilation tended to be shorter in the ACBT group than in the control group (64.9 hours vs 84.1 hours, p = 0.15). Length of time in need of non-invasive ventilation was significantly lower in the ACBT group than in the control group (5.0 days vs 6.7 days, p = 0.03). There was no significant difference in length of stay in the intensive care unit between the two groups (8.0 vs 9.4 days, p = 0.31). The use of ACBT may have positive effects in the treatment of patients with acute hypercapnic respiratory failure, resulting in a shorter length of time requiring non-invasive ventilation.