Factors predicting successful noninvasive ventilation in acute lung injury

Monitoring patients with acute respiratory failure during non-invasive respiratory support to minimize harm and identify treatment failure

Non-invasive respiratory support (NRS), including high flow nasal oxygen therapy, continuous positive airway pressure and non-invasive ventilation, is a cornerstone in the management of critically ill patients who develop acute respiratory failure (ARF). Overall, NRS reduces the work of breathing and relieves dyspnea in many patients with ARF, sometimes avoiding the need for intubation and invasive mechanical ventilation with variable efficacy across diverse clinical scenarios. Nonetheless, prolonged exposure to NRS in the presence of sustained high respiratory drive and effort can result in respiratory muscle fatigue, cardiovascular collapse, and impaired oxygen delivery to vital organs, leading to poor outcomes in patients who ultimately fail NRS and require intubation. Assessment of patients' baseline characteristics before starting NRS, close physiological monitoring to evaluate patients' response to respiratory support, adjustment of device settings and interface, and, most importantly, early identification of failure or of paramount importance to avoid the negative consequences of delayed intubation. This review highlights the role of respiratory monitoring across various modalities of NRS in patients with ARF including dyspnea, general respiratory parameters, measures of drive and effort, and lung imaging. It includes technical specificities related to the target population and emphasizes the importance of clinicians' physiological understanding and tailoring clinical decisions to individual patients' needs.

Volume OXygenation index in predicting the efficacy of early non-invasive ventilation in patients with acute hypoxic respiratory failure: A multicenter study

BACKGROUND

The Volume OXygenation (VOX) index was initially designed to predict treatment failure of high-flow nasal cannula therapy. However, its predictive power for non-invasive ventilation (NIV) remains uncertain.

OBJECTIVES

To evaluate the predictive capability of the VOX index regarding treatment failure in patients undergoing NIV.

METHODS

This retrospective study was conducted in three hospitals from September 2017 to September 2021. Patients with acute hypoxic respiratory failure (AHRF) who underwent early NIV treatment were categorized into high-risk and low-risk groups based on the 2-hour NIV VOX Youden index.

RESULTS

At 2 h of NIV, the area under the receiver operating characteristic curve for predicting NIV failure using the VOX index was 0.843 (95 % CI 0.805-0.882). Using a VOX value threshold of 20.45 to predict NIV failure, the sensitivity was 69.1 %, and the specificity was 94.4 %. Following NIV treatment, the low-risk group had a lower intubation rate (7.98 % vs. 77 %, P < 0.05) and mortality rate (4.79 % vs. 17.5 %, P < 0.05).

CONCLUSION

In early NIV treatment for AHRF, the VOX index obtained after 2 h of NIV demonstrates a strong predictive power for NIV failure. Patients with a VOX value > 20.45 have a low probability of NIV failure, suggesting that it can be used as an evaluation index to assess the efficacy of NIV.

PaCO2 is nonlinearly associated with NIV failure in patients with hypoxemic respiratory failure

OBJECTIVE

To explore the association between PaCO2 and noninvasive ventilation (NIV) failure in patients with hypoxemic respiratory failure.

METHODS

A retrospective study was performed in a respiratory ICU of a teaching hospital. Patients admitted to ICU between 2011 and 2019 were screened. We enrolled the patients with hypoxemic respiratory failure. However, patients who used NIV due to acute-on-chronic respiratory failure or heart failure were excluded. Data before the use of NIV were collected. Requirement of intubation was defined as NIV failure.

RESULTS

A total of 1029 patients were enrolled in final analysis. The rate of NIV failure was 45% (461/1029). A nonlinear relationship between PaCO2 and NIV failure was found by restricted cubic splines (p = 0.03). The inflection point was 32 mmHg. The rate of NIV failure was 42% (224/535) in patients with PaCO2 >32 mmHg. However, it increased to 48% (237/494) in those with PaCO2 ≤ 32 mmHg. The crude and adjusted hazard ratio (HR) for NIV failure was 1.36 (95%CI:1.13-1.64) and 1.23(1.01-1.49), respectively, if the patients with PaCO2 >32 mmHg were set as reference. In patients with PaCO2 ≤ 32 mmHg, one unit increment of PaCO2 was associated with 5% reduction of NIV failure. However, it did not associate with NIV failure in patients with PaCO2 >32 mmHg.

CONCLUSIONS

PaCO2 and NIV failure was nonlinear relationship. The inflection point was 32 mmHg. Below the inflection point, lower PaCO2 was associated with higher NIV failure. However, it did not associate with NIV failure above this point.

The role of ultrasound in predicting non-invasive ventilation outcomes: a systematic review

Purpose

To systematically review and compare ultrasonographic methods and their utility in predicting non-invasive ventilation (NIV) outcomes.

Methods

A systematic review was performed using the PubMed, Medline, Embase, and Cochrane databases from January 2015 to March 2023. The search terms included the following: ultrasound, diaphragm, lung, prediction, non-invasive, ventilation, and outcomes. The inclusion criteria were prospective cohort studies on adult patients requiring non-invasive ventilation in the emergency department or inpatient setting.

Results

Fifteen studies were analyzed, which comprised of 1,307 patients (n = 942 for lung ultrasound score studies; n = 365 patients for diaphragm dysfunction studies). Lung ultrasound scores (LUS) greater than 18 were associated with NIV failure with a sensitivity 62-90.5% and specificity 60-91.9%. Similarly, a diaphragm thickening fraction (DTF) of less than 20% was also associated with NIV failure with a sensitivity 80-84.6% and specificity 76.3-91.5%.

Conclusion

Predicting NIV failure can be difficult by routine initial clinical impression and diagnostic work up. This systematic review emphasizes the importance of using lung and diaphragm ultrasound, in particular the lung ultrasound score and diaphragm thickening fraction respectively, to accurately predict NIV failure, including the need for ICU-level of care, requiring invasive mechanical ventilation, and resulting in higher rates of mortality.

Acute dyspnea in the emergency department: a clinical review

Acute dyspnea represents one of the most frequent symptoms leading to emergency room evaluation. Its significant prognostic value warrants a careful evaluation. The differential diagnosis of dyspnea is complex due to the lack of specificity and the loose association between its intensity and the severity of the underlying pathological condition. The initial assessment of dyspnea calls for prompt diagnostic evaluation and identification of optimal monitoring strategy and provides information useful to allocate the patient to the most appropriate setting of care. In recent years, accumulating evidence indicated that lung ultrasound, along with echocardiography, represents the first rapid and non-invasive line of assessment that accurately differentiates heart, lung or extra-pulmonary involvement in patients with dyspnea. Moreover, non-invasive respiratory support modalities such as high-flow nasal oxygen and continuous positive airway pressure have aroused major clinical interest, in light of their efficacy and practicality to treat patients with dyspnea requiring ventilatory support, without using invasive mechanical ventilation. This clinical review is focused on the pathophysiology of acute dyspnea, on its clinical presentation and evaluation, including ultrasound-based diagnostic workup, and on available non-invasive modalities of respiratory support that may be required in patients with acute dyspnea secondary or associated with respiratory failure.

Helmet noninvasive ventilation in acute hypoxic respiratory failure

PURPOSE OF REVIEW

Invasive mechanical ventilation is a lifesaving intervention for patients with severe acute hypoxic respiratory failure (AHRF), but it is associated with neuromuscular, cognitive, and infectious complications. Noninvasive ventilation (NIV) may provide sufficient respiratory support without these complications. The helmet interface for NIV could address concerns raised for the use of NIV as first-line therapy in AHRF. This review will summarize and appraise the current evidence for helmet NIV in AHRF.

RECENT FINDINGS

There are only six randomized controlled trials comparing helmet NIV to standard nasal cannula, facemask NIV, or high-flow nasal oxygen in patients with AHRF. Lower rates of endotracheal intubations and fewer days of mechanical ventilation were reported, with inconsistent findings on patient survival. Facemask NIV may worsen preexisting lung injury, delay intubations, and be inferior at delivering lung protective ventilation strategies compared with mechanical ventilation. The helmet interface could circumvent some of these concerns through the delivery of higher positive end expiratory pressure and more uniform distribution of negative pleural pressure.

SUMMARY

There is limited evidence to support or refute the use of helmet NIV in AHRF. Further studies investigating the interface of helmet in NIV as a separate clinical entity are needed.

Advantages and drawbacks of helmet noninvasive support in acute respiratory failure

INTRODUCTION

Non-invasive ventilation (NIV) represents an effective strategy for managing acute respiratory failure. Facemask NIV is strongly recommended in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with hypercapnia and acute cardiogenic pulmonary edema (ACPE). Its role in managing acute hypoxemic respiratory failure (AHRF) remains a debated issue. NIV and continuous positive airway pressure (CPAP) delivered through the helmet are recently receiving growing interest for AHRF management.

AREAS COVERED

In this narrative review, we discuss the clinical applications of helmet support compared to the other available noninvasive strategies in the different phenotypes of acute respiratory failure.

EXPERT OPINION

Helmets enable the use of high positive end-expiratory pressure, which may protect from self-inflicted lung injury: in AHRF, the possible superiority of helmet support over other noninvasive strategies in terms of clinical outcome has been hypothesized in a network metanalysis and a randomized trial, but has not been confirmed by other investigations and warrants confirmation. In AECOPD patients, helmet efficacy may be inferior to that of face masks, and its use prompts caution due to the risk of CO₂ rebreathing. Helmet support can be safely applied in hypoxemic patients with ACPE, with no advantages over facemasks.

Non-invasive ventilation for acute hypoxemic respiratory failure, including COVID-19

Optimal initial non-invasive management of acute hypoxemic respiratory failure (AHRF), of both coronavirus disease 2019 (COVID-19) and non-COVID-19 etiologies, has been the subject of significant discussion. Avoidance of endotracheal intubation reduces related complications, but maintenance of spontaneous breathing with intense respiratory effort may increase risks of patients' self-inflicted lung injury, leading to delayed intubation and worse clinical outcomes. High-flow nasal oxygen is currently recommended as the optimal strategy for AHRF management for its simplicity and beneficial physiological effects. Non-invasive ventilation (NIV), delivered as either pressure support or continuous positive airway pressure via interfaces like face masks and helmets, can improve oxygenation and may be associated with reduced endotracheal intubation rates. However, treatment failure is common and associated with poor outcomes. Expertise and knowledge of the specific features of each interface are necessary to fully exploit their potential benefits and minimize risks. Strict clinical and physiological monitoring is necessary during any treatment to avoid delays in endotracheal intubation and protective ventilation. In this narrative review, we analyze the physiological benefits and risks of spontaneous breathing in AHRF, and the characteristics of tools for delivering NIV. The goal herein is to provide a contemporary, evidence-based overview of this highly relevant topic.

Prediction of Noninvasive Ventilation Failure in a Mixed Population Visiting the Emergency Department in a Tertiary Care Center in India

Background

Noninvasive ventilation (NIV) is an established first-line treatment of acute respiratory failure both in emergency departments (ED) and intensive care unit (ICU) settings. It is however not always successful.

Materials and methods

Prospective, observational study was done among patients above 18 years presenting with acute respiratory failure initiated on NIV. Patients were placed in one of two groups covering successful NIV treatment and NIV failure. Two groups were compared on four variables: initial respiratory rate (RR), initial high-sensitivity C-reactive protein (hs-CRP), PaO₂/FiO₂ ratio (p/f ratio), and heart rate, acidosis, consciousness, oxygenation, and respiratory rate (HACOR) score at the end of 1 hour of initiation of NIV.

Results

A total of 104 patients fulfilling the inclusion criteria were included in the study, of which 55 (52.88%) were exclusively treated with NIV (NIV success group), and 49 (47.11%) required endotracheal intubation and mechanical ventilation (NIV failure group). Noninvasive ventilation failure group had a higher mean initial RR compared with NIV success group (40.65 ± 3.88 vs 31.98 ± 3.15, p <0.001). Mean initial PaO₂/FiO₂ ratio was also significantly lower in the NIV failure group (184.57 ± 50.33 vs 277.29 ± 34.70, p <0.001). Odds ratio for successful NIV treatment with a high initial RR was 0.503 (95% confidence interval (CI), 0.390-0.649) and with a higher initial PaO₂/FiO₂ ratio was 1.053 (95% CI: 1.032-1.071 and with a HACOR score of >5 at the end of 1 hour of initiation of NIV was highly associated with NIV failure (p <0.001). A high initial level of hs-CRP was 0.949 (95% CI: 0.927-0.970).

Conclusion

Noninvasive ventilation failure could be predicted with information available at presentation in ED, and unnecessary delay in endotracheal intubation could possibly be prevented.

How to cite this article

Mathen PG, Kumar KPG, Mohan N, Sreekrishnan TP, Nair SB, Krishnan AK, et al. Prediction of Noninvasive Ventilation Failure in a Mixed Population Visiting the Emergency Department in a Tertiary Care Center in India. Indian J Crit Care Med 2022;26(10):1115-1119.

Non-invasive ventilatory support and high-flow nasal oxygen as first-line treatment of acute hypoxemic respiratory failure and ARDS

The role of non-invasive respiratory support (high-flow nasal oxygen and noninvasive ventilation) in the management of acute hypoxemic respiratory failure and acute respiratory distress syndrome is debated. The oxygenation improvement coupled with lung and diaphragm protection produced by non-invasive support may help to avoid endotracheal intubation, which prevents the complications of sedation and invasive mechanical ventilation. However, spontaneous breathing in patients with lung injury carries the risk that vigorous inspiratory effort, combined or not with mechanical increases in inspiratory airway pressure, produces high transpulmonary pressure swings and local lung overstretch. This ultimately results in additional lung damage (patient self-inflicted lung injury), so that patients intubated after a trial of noninvasive support are burdened by increased mortality. Reducing inspiratory effort by high-flow nasal oxygen or delivery of sustained positive end-expiratory pressure through the helmet interface may reduce these risks. In this physiology-to-bedside review, we provide an updated overview about the role of noninvasive respiratory support strategies as early treatment of hypoxemic respiratory failure in the intensive care unit. Noninvasive strategies appear safe and effective in mild-to-moderate hypoxemia (PaO₂/FiO₂ > 150 mmHg), while they can yield delayed intubation with increased mortality in a significant proportion of moderate-to-severe (PaO₂/FiO₂ ≤ 150 mmHg) cases. High-flow nasal oxygen and helmet noninvasive ventilation represent the most promising techniques for first-line treatment of severe patients. However, no conclusive evidence allows to recommend a single approach over the others in case of moderate-to-severe hypoxemia. During any treatment, strict physiological monitoring remains of paramount importance to promptly detect the need for endotracheal intubation and not delay protective ventilation.

The predictive ability of SAPS II, APACHE II, SAPS III, and APACHE IV to assess outcome and duration of mechanical ventilation in respiratory intensive care unit

Objectives:

The objective is to determine utility of SAPS II, APACHE II, SAPS III, and APACHE IV scoring system in assessing outcome in mechanically ventilated patients in respiratory intensive care unit and to predict duration of mechanical ventilation (MV).

Materials and Methods:

A prospective observational study where 83 mechanically ventilated patients were grouped into Group 1 (n₁ = 40, NIV) and Group 2 (n₂ = 43, Invasive ventilation) was conducted. SAPS II, APACHE II, SAPS III, and APACHE IV scores based predicted mortality (PM) were collected at day 1, and day 3. Outcomes (on day 7) were grouped into negative and positive. (NIV-negative outcome = Home NIV, intubation or death; positive outcome = NIV free. Invasive group-positive outcome = Extubation; negative outcome = Death). Binary logistic regression was applied to predict duration of MV (> or < 5 days).

Results:

The data were analyzed using SPSS version 17.0 trials comparisons of PM on day 1 with SAPS II (P < 0.05) and APACHE IV (P < 0.007) were significant predictors of clinical outcomes in Group 1 where as in Group 2, none of the system could predict significantly. On day 3, Group 1 analysis revealed SAPS II (P < 0.002), SAPS III (P < 0.03), and APACHE IV (P < 0.004) based PM as significant predictors of outcome. APACHE II (P < 0.05) and APACHE IV (P < 0.02) PM were significant in Group 2. On day 3, APACHE IV could significantly predict (P < 0.05) duration of MV (>5 or < 5) while A-a gradient (P < 0.09) predicted poorly in Group 1. In Group 2, APACHE IV was a poor predictor (P < 0.09). Two full logistic regression models were also formulated for both the groups.

Conclusion:

Study concludes that day 3 severity scores are more significant predictors of outcome and duration. APACHE IV scoring system was found more effective than other systems, not only significantly differentiating outcomes of MV but also predicting duration of NIV.

Predictive Factors for Failure of Noninvasive Ventilation in Adult Intensive Care Unit: A Retrospective Clinical Study

Background

Noninvasive ventilation (NIV) has been reported to be beneficial for patients with acute respiratory failure in intensive care unit (ICU); however, factors that influence the clinical outcome of NIV were unclarified. We aim to determine the factors that predict the failure of NIV in critically ill patients with acute respiratory failure (ARF). Setting. Adult mixed ICU in a medical university affiliated hospital. Patients and Methods. A retrospective clinical study using data from critical adult patients with initial NIV admitted to ICU in the period August 2016 to November 2017. Failure of NIV was regarded as patients needing invasive ventilation. Logistic regression was employed to determine the risk factor(s) for NIV, and a predictive model for NIV outcome was set up using risk factors.

Results

Of 101 included patients, 50 were unsuccessful. Although more than 20 variables were associated with NIV failure, multivariate logistic regression demonstrated that only ideal body weight (IBW) (OR 1.110 (95%1.027-1.201), P=0.009), the maximal heart rate during NIV period (HR-MAX) (OR 1.024 (1.004-1.046), P=0.021), the minimal respiratory rate during NIV period (RR-MIN) (OR 1.198(1.051-1.365), P=0.007), and the highest body temperature during NIV period (T-MAX) (OR 1.838(1.038-3.252), P=0.037) were independent risk factors for NIV failure. We set up a predictive model based on these independent risk factors, whose area under the receiver operating characteristic curve (AUROC) was 0.783 (95% CI: 0.676-0.899, P < 0.001), and the sensitivity and specificity of model were 68.75% and 71.43%, respectively, with the optimal cut-off value of 0.4863.

Conclusion

IBW, HR-MAX, RR-MIN, and T-MAX were associated with NIV failure in patients with ARF. A predictive model based on the risk factors could help to discriminate patients who are vulnerable to NIV failure.

Consideration of the respiratory support strategy of severe acute respiratory failure caused by SARS-CoV-2 infection in children

The recent ongoing outbreak of severe pneumonia associated with a novel coronavirus (SARS-CoV-2), currently of unknown origin, creates a world emergency that has put global public health institutions on high alert. At present there is limited clinical information of the SARS-CoV-2 and there is no specific treatment recommended, although technical guidances and suggestions have been developed and will continue to be updated as additional information becomes available. Preventive treatment has an important role to control and avoid the spread of severe respiratory disease, but often is difficult to obtain and sometimes cannot be effective to reduce the risk of deterioration of the underlining lung pathology. In order to define an effective and safe treatment for SARS-CoV-2-associated disease, we provide considerations on the actual treatments, on how to avoid complications and the undesirable side effects related to them and to select and apply earlier the most appropriate treatment. Approaching to treat severe respiratory disease in infants and children, the risks related to the development of atelectasis starting invasive or non-invasive ventilation support and the risk of oxygen toxicity must be taken into serious consideration. For an appropriate and effective approach to treat severe pediatric respiratory diseases, two main different strategies can be proposed according to the stage and severity of the patient conditions: patient in the initial phase and with non-severe lung pathology and patient with severe initial respiratory impairment and/or with delay in arrival to observation. The final outcome is strictly connected with the ability to apply an appropriate treatment early and to reduce all the complications that can arise during the intensive care admission.

Use of noninvasive ventilation in severe acute respiratory distress syndrome due to accidental chlorine inhalation: a case report

Acute respiratory distress syndrome is characterized by diffuse inflammatory lung injury and is classified as mild, moderate, and severe. Clinically, hypoxemia, bilateral opacities in lung images, and decreased pulmonary compliance are observed. Sepsis is one of the most prevalent causes of this condition (30 - 50%). Among the direct causes of acute respiratory distress syndrome, chlorine inhalation is an uncommon cause, generating mucosal and airway irritation in most cases. We present a case of severe acute respiratory distress syndrome after accidental inhalation of chlorine in a swimming pool, with noninvasive ventilation used as a treatment with good response in this case. We classified severe acute respiratory distress syndrome based on an oxygen partial pressure/oxygen inspired fraction ratio <100, although the Berlin classification is limited in considering patients with severe hypoxemia managed exclusively with noninvasive ventilation. The failure rate of noninvasive ventilation in cases of acute respiratory distress syndrome is approximately 52% and is associated with higher mortality. The possible complications of using noninvasive positive-pressure mechanical ventilation in cases of acute respiratory distress syndrome include delays in orotracheal intubation, which is performed in cases of poor clinical condition and with high support pressure levels, and deep inspiratory efforts, generating high tidal volumes and excessive transpulmonary pressures, which contribute to ventilation-related lung injury. Despite these complications, some studies have shown a decrease in the rates of orotracheal intubation in patients with acute respiratory distress syndrome with low severity scores, hemodynamic stability, and the absence of other organ dysfunctions.

Assessment of heart rate, acidosis, consciousness, oxygenation, and respiratory rate to predict noninvasive ventilation failure in hypoxemic patients

PURPOSE

To develop and validate a scale using variables easily obtained at the bedside for prediction of failure of noninvasive ventilation (NIV) in hypoxemic patients.

METHODS

The test cohort comprised 449 patients with hypoxemia who were receiving NIV. This cohort was used to develop a scale that considers heart rate, acidosis, consciousness, oxygenation, and respiratory rate (referred to as the HACOR scale) to predict NIV failure, defined as need for intubation after NIV intervention. The highest possible score was 25 points. To validate the scale, a separate group of 358 hypoxemic patients were enrolled in the validation cohort.

RESULTS

The failure rate of NIV was 47.8 and 39.4% in the test and validation cohorts, respectively. In the test cohort, patients with NIV failure had higher HACOR scores at initiation and after 1, 12, 24, and 48 h of NIV than those with successful NIV. At 1 h of NIV the area under the receiver operating characteristic curve was 0.88, showing good predictive power for NIV failure. Using 5 points as the cutoff value, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for NIV failure were 72.6, 90.2, 87.2, 78.1, and 81.8%, respectively. These results were confirmed in the validation cohort. Moreover, the diagnostic accuracy for NIV failure exceeded 80% in subgroups classified by diagnosis, age, or disease severity and also at 1, 12, 24, and 48 h of NIV. Among patients with NIV failure with a HACOR score of >5 at 1 h of NIV, hospital mortality was lower in those who received intubation at ≤12 h of NIV than in those intubated later [58/88 (66%) vs. 138/175 (79%); p = 0.03).

CONCLUSIONS

The HACOR scale variables are easily obtained at the bedside. The scale appears to be an effective way of predicting NIV failure in hypoxemic patients. Early intubation in high-risk patients may reduce hospital mortality.

Noninvasivepositive pressure ventilation vsinvasive mechanical ventilation as first-line therapy for acute hypoxemic respiratory failure in cancer patients

PURPOSE

The objective was to describe the characteristics and outcomes of critically ill cancer patients who received noninvasive positive pressure ventilation (NIPPV) vs invasive mechanical ventilation as first-line therapy for acute hypoxemic respiratory failure.

MATERIAL AND METHODS

A retrospective cohort study of consecutive adult intensive care unit (ICU) cancer patients who received either conventional invasive mechanical ventilation or NIPPV as first-line therapy for hypoxemic respiratory failure.

RESULTS

Of the 1614 patients included, the NIPPV failure group had the greatest hospital length of stay, ICU length of stay, ICU mortality (71.3%), and hospital mortality (79.5%) as compared with the other 2 groups (P < .0001). The variables independently associated with NIPPV failure included younger age (odds ratio [OR], 0.99; 95% confidence interval [CI], 0.98-0.99; P=.031), non-Caucasian race (OR, 1.61; 95% CI, 1.14-2.26; P=.006), presence of a hematologic malignancy (OR, 1.87; 95% CI, 1.33-2.64; P=.0003), and a higher Sequential Organ Failure Assessment score (OR, 1.12; 95% CI, 1.08-1.17; P < .0001). There was no difference in mortality when comparing early vs late intubation (less than or greater than 24 or 48 hours) for the NIPPV failure group.

CONCLUSION

Noninvasive positive pressure ventilation failure is an independent risk factor for ICU mortality, but NIPPV patients who avoided intubation had the best outcomes compared with the other groups. Early vs late intubation did not have a significant impact on outcomes.

Use of noninvasive ventilation in severe acute respiratory distress syndrome due to accidental chlorine inhalation: a case report

Acute respiratory distress syndrome is characterized by diffuse inflammatory lung injury and is classified as mild, moderate, and severe. Clinically, hypoxemia, bilateral opacities in lung images, and decreased pulmonary compliance are observed. Sepsis is one of the most prevalent causes of this condition (30 - 50%). Among the direct causes of acute respiratory distress syndrome, chlorine inhalation is an uncommon cause, generating mucosal and airway irritation in most cases. We present a case of severe acute respiratory distress syndrome after accidental inhalation of chlorine in a swimming pool, with noninvasive ventilation used as a treatment with good response in this case. We classified severe acute respiratory distress syndrome based on an oxygen partial pressure/oxygen inspired fraction ratio <100, although the Berlin classification is limited in considering patients with severe hypoxemia managed exclusively with noninvasive ventilation. The failure rate of noninvasive ventilation in cases of acute respiratory distress syndrome is approximately 52% and is associated with higher mortality. The possible complications of using noninvasive positive-pressure mechanical ventilation in cases of acute respiratory distress syndrome include delays in orotracheal intubation, which is performed in cases of poor clinical condition and with high support pressure levels, and deep inspiratory efforts, generating high tidal volumes and excessive transpulmonary pressures, which contribute to ventilation-related lung injury. Despite these complications, some studies have shown a decrease in the rates of orotracheal intubation in patients with acute respiratory distress syndrome with low severity scores, hemodynamic stability, and the absence of other organ dysfunctions.

Noninvasive ventilation on mortality of acute respiratory distress syndrome

[Purpose] The aim of this study was to assess the efficacy of noninvasive ventilation (NIV) in acute respiratory distress syndrome (ARDS). [Subjects and Methods] The clinical data of 58 patients with ARDS that required mechanical ventilation in two intensive care units (ICU) was reviewed. [Results] Endotracheal intubation was performed in 55.17% of the total patients and in 39.53% of the patients who received NIV treatment. The APACHE II score for patients who only received IV was significantly higher than those who only underwent NIV (25.67 ± 5.30 vs. 18.12 ± 7.20). However, there were no significant differences in 28-day/90-day survival rates, duration of mechanical ventilation, and length of ICU stay between these two groups. For patients from a NIV-to-IV group, the APACHE II scores before endotracheal intubation were higher than the scores from IV patients (26.12 ± 4.08 vs. 21.94 ± 6.10). The 90-day survival rate in the NIV-to-IV group was significantly lower than that of the IV-only group (23.5% vs. 73.3%), although there was no difference in the 28-day survival rate between the two groups. [Conclusion] The application of NIV reduces the percentage of patients requiring endotracheal intubation.

Comparison of different scores as predictors of mechanical ventilation in drug overdose patients

The decision of intubation and mechanical ventilation in poisoned patients with impaired consciousness can be a difficult task. The present study aimed to evaluate the power of Glasgow Coma Scale (GCS), acute physiology and chronic health evaluation (APACHE II), rapid acute physiology score (RAPS) and rapid emergency medicine score (REMS) at admission in predicting the need of intubation and mechanical ventilation in drug overdose patients with disturbed consciousness level (DCL). This prospective observational study was conducted on 104 poisoned patients who were admitted to Tanta Toxicological Unit with a DCL. Four scoring systems (GCS, APACHE II, RAPS and REMS) were recorded for all patients on admission. Discrimination was evaluated using receiver operating characteristics curve and calculating the area under the curve (AUC). Twenty-four cases required mechanical ventilation. The mechanically ventilated patients had significantly lower value of GCS and higher values of APACHE II, REMS and RAPS than other group ( p < 0.001). Although the APACHE II score has the best AUC value (0.796) in predicting mechanical ventilation, there was no statistically significant difference between the four scores. GCS > 8 had 100% negative predictive value, while REMS > 8 had 100% positive predictive value.

Acute respiratory distress syndrome: Predictors of noninvasive ventilation failure and intensive care unit mortality in clinical practice

PURPOSE

Noninvasive ventilation (NIV) is used as an initial ventilatory support in acute respiratory distress syndrome (ARDS), but its utility is unclear, and persistence in those who do not improve may delay intubation and lead to adverse outcomes. Hence, it becomes imperative to have a clear understanding of selecting patients who will benefit from this modality.

METHODS

In this prospective observational study, we included all consecutive adults, over a 3-year period, who fulfilled criteria for ARDS by the Berlin definition. Basic demographics, ventilatory support, intensive care unit course, and outcome were recorded.

RESULTS

Of 170 patients, 96 (56.47%) were initially managed with NIV. Noninvasive ventilation failure was seen in 42 (43.75%) of 96, and low baseline PaO2/FIO2, shock, and ARDS severity were associated with NIV failure. Overall intensive care unit mortality was 63 (37.1%) of 170, and high Acute Physiology and Chronic Health Evaluation II score, low PaO2/FIO2, shock, and ARDS severity were associated with increased mortality. Noninvasive ventilation failure and mortality were significantly higher in moderate and severe ARDS.

CONCLUSIONS

Noninvasive ventilation maybe useful in selected patients with mild ARDS but should be used with great caution in moderate and severe ARDS, as failure risk is high. In addition, low PaO2/FIO2 and shock are associated with NIV failure. Acute Physiology and Chronic Health Evaluation II score, shock, low PaO2/FIO2, and ARDS severity are associated with increased mortality.

A study on the role of noninvasive ventilation in mild-to-moderate acute respiratory distress syndrome

Aim:

There is sparse data on the role of noninvasive ventilation (NIV) in acute respiratory distress syndrome (ARDS) from India. Herein, we report our experience with the use of NIV in mild to moderate ARDS.

Materials and Methods:

This was a prospective observational study involving consecutive subjects of ARDS treated with NIV using an oronasal mask. Patients were monitored clinically with serial arterial blood gas analysis. The success of NIV, duration of NIV use, Intensive Care Unit stay, hospital mortality, and improvement in clinical and blood gas parameters were assessed. The success of NIV was defined as prevention of endotracheal intubation.

Results:

A total of 41 subjects (27 women, mean age: 30.9 years) were included in the study. Tropical infections followed by abdominal sepsis were the most common causes of ARDS. The use of NIV was successful in 18 (44%) subjects, while 23 subjects required intubation. The median time to intubation was 3 h. Overall, 19 (46.3%) deaths were encountered, all in those requiring invasive ventilation. The mean duration of ventilation was significantly higher in the intubated patients (7.1 vs. 2.6 days, P = 0.004). Univariate analysis revealed a lack of improvement in PaO₂/FiO₂ at 1 h and high baseline Acute Physiology and Chronic Health Evaluation II (APACHE II) as predictors of NIV failure.

Conclusions:

Use of NIV in mild to moderate ARDS helped in avoiding intubation in about 44% of the subjects. A baseline APACHE II score of >17 and a PaO₂/FiO₂ ratio <150 at 1 h predicts NIV failure.

Mortality Prediction in Patients Undergoing Non-Invasive Ventilation in Intermediate Care

Background

Intermediate Care Units (ImCU) have become an alternative scenario to perform Non-Invasive Ventilation (NIV). The limited number of prognostic studies in this population support the need of mortality prediction evaluation in this context.

Objective

The objective of this study is to analyze the performance of Simplified Acute Physiology Score (SAPS) II and 3 in patients undergoing NIV in an ImCU. Additionally, we searched for new variables that could be useful to customize these scores, in order to improve mortality prediction.

Design

Cohort study with prospectively collected data from all patients admitted to a single center ImCU who received NIV. The SAPS II and 3 scores with their respective predicted mortality rates were calculated. Discrimination and calibration were evaluated by calculating the area under the receiver operating characteristic curve (AUC) and with the Hosmer-Lemeshow goodness of fit test for the models, respectively. Binary logistic regression was used to identify new variables to customize the scores for mortality prediction in this setting.

Patients

The study included 241 patients consecutively admitted to an ImCU staffed by hospitalists from April 2006 to December 2013.

Key Results

The observed in-hospital mortality was 32.4% resulting in a Standardized Mortality Ratio (SMR) of 1.35 for SAPS II and 0.68 for SAPS 3. Mortality discrimination based on the AUC was 0.73 for SAPS II and 0.69 for SAPS 3. Customized models including immunosuppression, chronic obstructive pulmonary disease (COPD), acute pulmonary edema (APE), lactic acid, pCO2 and haemoglobin levels showed better discrimination than old scores with similar calibration power.

Conclusions

These results suggest that SAPS II and 3 should be customized with additional patient-risk factors to improve mortality prediction in patients undergoing NIV in intermediate care.

Evaluation of efficacy of non-invasive ventilation in Non-COPD and non-trauma patients with acute hypoxemic respiratory failure: A systematic review and meta-analysis

Non-invasive ventilation (NIV) has been widely supported in the past two decades as an effective application in avoiding the need for endotracheal intubation (ETI) and reducing associated mortality in acute hypoxemic respiratory failure (AHRF) patients. However, the efficacy of NIV in AHRF patients, non-related to chronic obstructive pulmonary disease (COPD) and trauma is still controversial in the field of medical research. This retrospective study aimed to evaluate the efficacy of NIV as an adjunctive therapy in non-COPD and non-traumatic AHRF patients. Data of 11 randomized control trials (RCTs), which were conducted between 1990 and 2010 to determine the efficacy of NIV in non-COPD and non-traumatic AHRF patients, were reviewed from the PUBMED, MEDLINE, Cochrane Library, and EMBASE databases. Parameters monitored in this study included the ETI rate, fatal complications, mortality rate of patients, and their ICU and hospital duration of stay. Overall results showed a statistically significant decrease in the rate of ETI, mortality, and fatal complications along with reduced ICU and hospital length of stay in non-COPD and non-trauma AHRF patients of various etiologies. This systematic review suggests that non-COPD and non-trauma AHRF patients can potentially benefit from NIV as compared with conventional treatment methods. Observations from various cohort studies, observational studies, and previously published literature advocate on the efficacy of NIV for treating non-COPD and non-traumatic AHRF patients. However, considering the diversity of studied populations, further studies and more specific trials on less heterogeneous AHRF patient groups are needed to focus on this aspect.

Can non-invasive positive pressure ventilation prevent endotracheal intubation in acute lung injury/acute respiratory distress syndrome? A meta-analysis

The role of non-invasive positive pressure ventilation (NIPPV) in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is controversial. The aim of this study was to investigate whether NIPPV could prevent endotracheal intubation and decrease mortality rate in patients with ALI/ARDS. Randomized controlled trials (RCT) which reported endotracheal intubation and mortality rate in patients with ALI/ARDS treated by NIPPV were identified in Pubmed, Medline, Embase, Central Cochrane Controlled Trials Register, Chinese National Knowledge Infrastructure, reference lists and by manual searches. Fixed- and random-effects models were used to calculate pooled relative risks. This meta-analysis included six RCT involving 227 patients. The results showed that endotracheal intubation rate was lower in NIPPV (95% confidence interval (CI): 0.44-0.80, z = 3.44, P = 0.0006), but no significant difference was found either in intensive care unit (ICU) mortality (95% CI: 0.45-1.07, z = 1.65, P = 0.10) or in hospital mortality (95% CI: 0.17-1.58, z = 1.16, P = 0.25). Only two studies discussed the aetiology of ALI/ARDS as pulmonary or extra-pulmonary, and neither showed statistical heterogeneity (I(2)  = 0%, χ(2)  = 0.31, P = 0.58), nor a significant difference in endotracheal intubation rate (95% CI: 0.35-9.08, z = 0.69, P = 0.49). In conclusion, the early use of NIPPV can decrease the endotracheal intubation rate in patients with ALI/ARDS, but does not change the mortality of these patients.

Timing of noninvasive ventilation failure: causes, risk factors, and potential remedies

Background

Identifying the predictors of noninvasive ventilation (NIV) failure has attracted significant interest because of the strong link between failure and poor outcomes. However, very little attention has been paid to the timing of the failure. This narrative review focuses on the causes of NIV failure and risk factors and potential remedies for NIV failure, based on the timing factor.

Results

The possible causes of immediate failure (within minutes to <1 h) are a weak cough reflex, excessive secretions, hypercapnic encephalopathy, intolerance, agitation, and patient-ventilator asynchrony. The major potential interventions include chest physiotherapeutic techniques, early fiberoptic bronchoscopy, changing ventilator settings, and judicious sedation. The risk factors for early failure (within 1 to 48 h) may differ for hypercapnic and hypoxemic respiratory failure. However, most cases of early failure are due to poor arterial blood gas (ABGs) and an inability to promptly correct them, increased severity of illness, and the persistence of a high respiratory rate. Despite a satisfactory initial response, late failure (48 h after NIV) can occur and may be related to sleep disturbance.

Conclusions

Every clinician dealing with NIV should be aware of these risk factors and the predicted parameters of NIV failure that may change during the application of NIV. Close monitoring is required to detect early and late signs of deterioration, thereby preventing unavoidable delays in intubation.

Rapid Shallow Breathing Index Survey, a Predictor of non-Invasive Ventilation Necessity in Patients With Chronic Obstructive Pulmonary Disease Exacerbation: An Analytical Descriptive Prospective Study

Background:

Patients with Chronic Obstructive Pulmonary Disease (COPD) are susceptible to respiratory failure which would ultimately lead to their hospitalization. Need to Non-Invasive Ventilation (NIV) is considered as the choice respiratory support in acute respiratory failure and is associated with a beneficial role in patients with COPD exacerbation. Hence, determining patients that would benefit NIV could be of great assistance.

Objectives:

We aimed at evaluating the use of Rapid Shallow Breathing Index (a ratio determined by the frequency (f) divided by the tidal volume (VT)) in NIV requirement in COPD patients.

Patients and Methods:

In a prospective descriptive study, ninety eight patients over 40 years old with documented COPD exacerbation who were referred to emergency department of Imam Reza hospital, Tabriz, Iran were studied. Rapid Shallow Breathing Index (RSBI), ABG parameters and APACHE II scoring were measured in each patient. Quantitative data were analyzed by Student's t-test and One-way ANOVA and qualitative data were analyzed using chi square (X2). Findings were analyzed with SPSS software version 16.

Results:

Patients requiring NIV included 43.9 % of all studied patients. RSBI and APACHE II score with sensitivity of 94.8 %, (cut off point = 110) and 72 % (cut off point = 14) respectively, had high diagnostic sensitivity and also the ability to predict patients requiring NIV. None of ABG parameters solely played a significant role in determining patients requiring NIV.

Conclusions:

RSBI and APACHE II score in patients with COPD exacerbation are of the ability to predict NIV requirement, as a predicting factor of Non-Invasive Ventilation requirement.

Noninvasive positive pressure ventilation for the treatment of acute respiratory distress syndrome following esophagectomy for esophageal cancer: a clinical comparative study

OBJECTIVE

To evaluate the therapeutic efficacy of noninvasive positive pressure ventilation (NPPV) in the treatment of acute respiratory distress syndrome (ARDS) following esophagectomy for esophageal cancer.

METHODS

In this retrospective evaluation, we included 64 patients with ARDS following esophagectomy for esophageal cancer between January 2009 and December 2011. The primary evaluations were 28-day fatality and actual fatality. The secondary evaluations were sex, age, onset time, pH value, PaO2/FiO2, sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation (APACHE-II) score, and presence or absence after surgery of major surgery-related complications such as cardiac arrest, anastomotic fistula, and acute renal dysfunction.

RESULTS

NPPV applied as the first-line intervention for ARDS following esophagectomy for esophageal cancer avoided intubation in 30 patients (30/64, 48.4%). There were no significant differences in gender, age, PaO2/FiO2, SOFA score, or APACHE-II score between the NPPV group and the patients who required invasive positive pressure ventilation (IPPV group) (P>0.05) at the time of onset, while differences in the PaO2/FiO2 (P<0.05) after 24 h of NPPV and presence of major surgery-related complications were highly significant (P<0.01).

CONCLUSIONS

NPPV may be an effective option for the treatment of ARDS/acute lung injury (ALI) following esophagectomy for esophageal cancer. However, conversion to invasive mechanical ventilation should be considered in patients with severe postoperative complications such as acute renal dysfunction and cardiac arrest and in those with PaO2/FiO2 <180 after 2 h of NPPV.

Aggressive treatment with noninvasive ventilation for mild acute hypoxemic respiratory failure after cardiovascular surgery: retrospective observational study

Background

Acute hypoxemic respiratory failure (AHRF) is one of the most serious complications after cardiovascular surgery. It remains unclear whether noninvasive ventilation (NIV) has potential as an effective therapy for AHRF after cardiovascular surgery, although many reports have described the use of NIV for AHRF after extubation. The aim of this study was to investigate the effectiveness of NIV in the early stage of mild AHRF after cardiovascular surgery.

Methods

We retrospectively analyzed all patients admitted to the intensive care unit after cardiovascular surgery, whose oxygenation transfer (PaO₂/FIO₂) deteriorated mildly after extubation, and in whom NIV was initiated. A two-way analysis of variance and the Bonferroni multiple comparisons procedure, the Mann–Whitney test, Fisher’s exact test or the χ²test was performed.

Results

A total of 94 patients with AHRF received NIV, of whom 89 patients (94%) successfully avoided endotracheal intubation (successful group) and five patients required reintubation (reintubation group). All patients, including the reintubated patients, were successfully weaned from mechanical ventilation and discharged from the intensive care unit. In the successful group, PaO₂/FIO₂ improved and the respiratory rate decreased significantly within 1 h after the start of NIV, and the improvement in PaO₂/FIO₂ remained during the whole NIV period.

Conclusion

We conclude that NIV is beneficial for mild AHRF after cardiovascular surgery when it is started within 3 h after mild deterioration of PaO₂/FIO₂. We also think that it is important not to hesitate before performing reintubation when NIV is judged to be ineffective.

The utility of clinical predictors of acute lung injury: towards prevention and earlier recognition

Despite significant advances in our understanding of the pathophysiology of acute lung injury, a lung-protective strategy of mechanical ventilation remains the only therapy with a proven survival advantage. Numerous pharmacologic therapies have failed to show benefit in multicenter clinical trials. The paradigm of early, goal-directed therapy of sepsis suggests greater clinical benefit may derive from initiating therapy prior to the onset of respiratory failure that requires mechanical ventilation. Thus, there is heightened interest in more accurate and complete characterization of high-risk patient populations and identification of patients in the early stage of acute lung injury, prior to the need for mechanical ventilation. This article discusses the growing literature on clinical predictors of acute lung injury (including risk factors for specific subgroups) with an emphasis on transfusion-related risk factors and recent research targeting the early identification of high-risk patients and those with early acute lung injury prior to the onset of respiratory failure.

Noninvasive positive pressure ventilation in patients with perioperative negative pressure pulmonary edema

Negative pressure pulmonary edema (NPPE) is a noncardiogenic pathological process that is treated with invasive ventilation via a tracheal tube. To investigate the feasibility and safety of noninvasive positive pressure ventilation (NPPV) as an alternative treatment for NPPE, we retrospectively reviewed charts of 15 perioperative NPPE patients. Eight patients were treated by NPPV and 7 were treated by invasive ventilation. Patient characteristics, duration of NPPV, duration of intensive care unit (ICU) stay, and maximum airway pressure were investigated for the NPPV-treated patients. All patients treated by NPPV had a patent airway after complete relief of the airway obstruction and recovered from NPPE symptoms within one postoperative day. Arterial blood gas analysis showed a significant improvement in the PaO(2)/FiO(2) ratio from 132 + or - 30 mmHg in the operating room to 282 + or - 77 mmHg at discontinuation of NPPV. Serious complications, such as ventilator-associated pneumonia or aspiration pneumonia, did not occur, and intubation was not required for any patient. Favorable outcomes in these cases suggest that NPPV could be a feasible and safe alternative for treating NPPE if the patency of the airway is restored.