Late presentation of acute hypercapnic respiratory failure carries a high mortality risk in COPD patients treated with ward-based NIV

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

Clinical practice of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Non-invasive ventilation (NIV) is an evidence-based treatment for acute respiratory failure in chronic obstructive pulmonary disease (COPD). However, suboptimal application of NIV in clinical practice, possibly due to poor guideline adherence, can impact patient outcomes. This study aims to evaluate guideline adherence to NIV for acute COPD exacerbations and explore its impact on mortality.

METHODS

This retrospective study was performed in two Dutch medical centers from 2019 to 2021. All patients admitted to the pulmonary ward or intensive care unit with a COPD exacerbation were included. An indication for NIV was considered in the event of a respiratory acidosis.

RESULTS

A total of 1162 admissions (668 unique patients) were included. NIV was started in 154 of the 204 admissions (76%) where NIV was indicated upon admission. Among 78 admissions where patients deteriorated later on, NIV was started in 51 admissions (65%). Considering patients not receiving NIV due to contra-indications or patient refusal, the overall guideline adherence rate was 82%. Common reasons for not starting NIV when indicated included no perceived signs of respiratory distress, opting for comfort care only, and choosing a watchful waiting approach. Better survival was observed in patients who received NIV when indicated compared to those who did not.

CONCLUSIONS

The adherence to guidelines regarding NIV initiation is good. Nevertheless, further improving NIV treatment in clinical practice could be achieved through training healthcare professionals to increase awareness and reduce reluctance in utilizing NIV. By addressing these factors, patient outcomes may be further enhanced.

Hypercapnic Failure in Acute Exacerbated COPD Patients: Severe Airflow Limitation as an Early Warning Signal

BACKGROUND

Hypercapnic failure is a severe complication of COPD disease progression, which is associated with a high morbidity and mortality. The aim of this study was to examine the association of comorbidity and clinical risk factors with the development of hypercapnia in acute exacerbated COPD patients.

METHODS

In this retrospective monocentric cohort study, we examined the influence of the clinical parameters and the comorbidity of hospitalized patients with the acute exacerbation of COPD on the development of hypercapnia by performing multivariate logistic regression and a receiver operating characteristic analysis.

RESULTS

In total, 275 patient cases with COPD exacerbation were enrolled during the period from January 2011 until March 2015, where 104 patients (37.8%) with hypercapnia were identified. The logistic regression analysis revealed severe airflow limitation (decreased FEV1) as the main factor associated with the development of hypercapnia. In the ROC analysis, we determined an FEV1 of 42.12%, which was predicted with a sensitivity of 82.6% and specificity of 55%, and an absolute value of FEV1 of 0.8 L, with a sensitivity of 0.62 and specificity of 0.79 as the cut off points, respectively. We could not verify an association with the patient's condition or the laboratory surrogate parameters of organ failure.

CONCLUSION

Severe airflow limitation is an important risk factor that is associated with hypercapnic failure in acute exacerbated COPD patients. Validation in prospective cohorts is warranted and should focus on more intensive monitoring of these at-risk patients.

Ward-Based Noninvasive Ventilation for Acute Hypercapnic Respiratory Failure Unrelated to Chronic Obstructive Pulmonary Disease

Background

The use of ward-based noninvasive ventilation (NIV) for acute hypercapnic respiratory failure (AHRF) unrelated to chronic obstructive pulmonary disease (COPD) remains controversial. This study evaluated the outcomes and failure rates associated with NIV application in the ward-based setting for patients with AHRF unrelated to COPD.

Methods

A multicentre, retrospective cohort study of patients with AHRF unrelated to COPD was conducted. COPD was not the main reason for hospital admission, treated with ward-based NIV between February 2004 and December 2018. All AHRF patients were eligible; exclusion criteria comprised COPD patients, age < 18 years, pre-NIV pH < 7.35, or a lack of pre-NIV blood gas. In-hospital mortality was the primary outcome; univariable and multivariable models were constructed. The obesity-related AHRF group included patients with AHRF due to obesity hypoventilation syndrome (OHS), and the non-obesity-related AHRF group included patients with AHRF due to pneumonia, bronchiectasis, neuromuscular disease, or fluid overload.

Results

In total, 479 patients were included in the analysis; 80.2% of patients survived to hospital discharge. Obesity-related AHRF was the indication for NIV in 39.2% of all episodes and was the aetiology with the highest rate of survival to hospital discharge (93.1%). In the multivariable analysis, factors associated with a higher risk of in-hospital mortality were increased age (odds ratio, 95% CI: 1.034, 1.017–1.051, P < 0.001) and pneumonia on admission (5.313, 2.326–12.131, P < 0.001). In the obesity-related AHRF group, pre-NIV pH < 7.15 was associated with significantly increased in-hospital mortality (7.800, 1.843–33.013, P=0.005); however, a pre-NIV pH 7.15–7.25 was not associated with increased in-hospital mortality (2.035, 0.523–7.915, P=0.305).

Conclusion

Pre-NIV pH and age have been identified as important predictors of surviving ward-based NIV treatment. Moreover, these data support the use of NIV in ward-based settings for obesity-related AHRF patients with pre-NIV pH thresholds down to 7.15. However, future controlled trials are required to confirm the effectiveness of NIV use outside critical care settings for obesity-related AHRF.

Development and Relevance of Hypercapnia in COPD

Background

Identification of patients who may become hypercapnic, or develop acidotic hypercapnic respiratory failure (AHRF), is important in chronic obstructive pulmonary disease (COPD) to avoid hospital admission and select patients for use of home NIV. This study aimed to identify factors associated with presence and development of hypercapnia.

Methods

1224 patients, 637 with COPD and 587 with alpha 1 antitrypsin deficiency (AATD), from 4 previously established patient cohorts, were included in cross-sectional analyses of hypercapnia (PaCO₂ ≥ 6.5 kPa or 48.8 mmHg), focusing on phenotypic features of COPD and mortality. Longitudinal associations of rising PaCO₂ were also assessed. A second cohort of 160 COPD patients underwent sleep studies and 1-year follow-up, analysing in a similar way, incorporating additional information from their sleep studies if appropriate.

Results

Hypercapnia was 15 times more common in usual COPD than AATD (p < 0.01) after adjustment for baseline differences by regression. Independent predictors of hypercapnia in COPD included FEV₁ and current use of oxygen; these variables, together with lack of emphysema, explained 11% of variance in CO₂. Increasing PaCO₂ also associated with higher risk of death (p=0.03). 44/160 patients exhibited sleep disordered breathing. The sleep study cohort also showed an association of low FEV₁ with hypercapnia. Prior hospital admission for AHRF was also clinically significant, being a feature of almost double the number of hypercapnic patients in both test and sleep study COPD cohorts.

Conclusion

Lower FEV₁ and prior AHRF are the main associations of hypercapnia in COPD, which carries a poor prognosis, particularly worsening over time.

Non-Invasive Ventilation in a Non-Standard Setting – Is it Safe to Ventilate Outside the ICU?

Non-invasive ventilation (NIV) is considered a fundamental method in treating patients with various disorders, requiring respiratory support. Often the lack of beds in the intensive care unit (ICU) and the concomitant medical conditions, which refer patients as unsuitable for aggressive treatment in the ICU, highlight the need of NIV application in general non-monitored wards and unusual settings – most commonly emergency departments, high-dependency units, pulmonary wards, and even ambulances. Recent studies suggest faster improvement of all physiological variables, reduced intubation rates, postoperative pulmonary complications and hospital mortality with better outcome and quality of life by early well-monitored ward-based NIV compared to standard medical therapy in patients with exacerbation of a chronic obstructive pulmonary disease, after a surgical procedure or acute hypoxemic respiratory failure in hematologic malignancies. NIV is a ceiling of treatment and a comfort measure in many patients with do-not-intubate orders due to terminal illnesses. NIV is beneficial only by proper administration with appropriate monitoring and screening for early NIV failure. Successful NIV application in a ward requires a well-equipped area and adequately trained multidisciplinary team. It could be initiated not only by attending physicians, respiratory technicians, and nurses but also by medical emergency teams. Ward-based NIV is supposed to be more cost-effective than NIV in the ICU, but further investigation is required to establish the safety and efficacy in hospital wards with a low nurse to patient ratio.