Hypercapnic encephalopathy syndrome: a new frontier for non-invasive ventilation?

Neurologic Complications of Cardiac and Pulmonary Disease

OBJECTIVE

The heart and lungs work as a functional unit through a complex interplay. The cardiorespiratory system is responsible for the delivery of oxygen and energy substrates to the brain. Therefore, diseases of the heart and lungs can lead to various neurologic illnesses. This article reviews various cardiac and pulmonary pathologies that can lead to neurologic injury and discusses the relevant pathophysiologic mechanisms.

LATEST DEVELOPMENTS

We have lived through unprecedented times over the past 3 years with the emergence and rapid spread of the COVID-19 pandemic. Given the effects of COVID-19 on the lungs and heart, an increased incidence of hypoxic-ischemic brain injury and stroke associated with cardiorespiratory pathologies has been observed. Newer evidence has questioned the benefit of induced hypothermia in patients with out-of-hospital cardiac arrest. Further, global collaborative initiatives such as the Curing Coma Campaign are underway with the goal of improving the care of patients with coma and disorders of consciousness, including those resulting from cardiac and pulmonary pathologies.

ESSENTIAL POINTS

The neurologic complications of cardiorespiratory disorders are common and present in various forms such as stroke or hypoxic and anoxic injury related to cardiac or respiratory failure. With the emergence of the COVID-19 pandemic, neurologic complications have increased in recent years. Given the intimate and interdependent dynamics of the heart, lungs, and brain, it is crucial for neurologists to be aware of the interplay between these organs.

Characteristics of Obese Patients with Acute Hypercapnia Respiratory Failure Admitted in the Department of Pneumology: An Observational Study of a North African Population

BACKGROUND

Acute hypercapnic respiratory failure (AHRF) is a common life-threatening event in patients with obesity hypoventilation syndrome (OHS).

OBJECTIVES

To study the clinical pattern, noninvasive ventilatory support, as well as the short- and long-term outcomes of patients with OHS admitted in a ward because of AHRF.

METHODS

We conducted a retrospective cohort study including all adults with OHS aged ≥ 18 - year - old, admitted in a 90-bed-ward for AHRF.

RESULTS

A total of 44 patients were included. Fifteen (34.1%) and 29 (65.9%) patients were diagnosed with malignant OHS (mOHS) and nonmalignant OHS (non-mOHS), respectively, while 36 (81.8%) had coexisting obstructive sleep apnea hypopnea syndrome (OSAHS). Patients with mOHS had a significantly higher rate of heart failure (100% vs. 31%; p < 0.001), chronic renal insufficiency (CRI) (73.3% vs. 41.4%; p = 0.04), and dyslipidemia (66.7% vs. 34.5%; p = 0.04) than those with non-mOHS. The mean forced vital capacity (FVC) in our patients was of 59.5% ± 18.5 of the predicted value, lower than what is usually reported in stable patients with OHS. At hospital admission, more than two-thirds (n = 34, 77.3%) were misdiagnosed as having asthma exacerbation (n = 4, 4.9.1%), chronic obstructive pulmonary disease (COPD) exacerbation (n = 12, 27.3%) and/or heart failure (n = 29, 65.9%). Acute pulmonary oedema (ACPE) (n = 16, 36.4%) and acute viral bronchitis (n = 12, 27.3%) were the main identified causal factors, while no cause could be determined in 5 (11.4%) patients. Noninvasive positive pressure ventilation (NIPPV) using bilevel positive airway pressure (BIPAP) was very highly effective to treat AHRF, with only 2.27% of patients failing the modality. Median overall duration of ventilation was 9 hours per day (1.3-20) and was significantly longer in patients with mOHS than in those with non-mOHS (10 [6-18] vs. 8 [1.3-20], respectively; p = 0.01). Forty two of the forty-three patients discharged alive were treated with BIPAP or continuous positive airway pressure (CPAP) in 26 and 16 patients, respectively. The probability of survival was 90% at 12 months, while the probability of readmission for a new episode of AHRF was 56% at 6 months and 22% at 12 months, respectively.

CONCLUSION

AHRF in OHS patients is a life-threatening event which can be successfully and safely treated with BIPAP, with a low long-term mortality even in patients with mOHS.

Ventilator Support and Oxygen Therapy in Palliative and End-of-Life Care in the Elderly

Elderly patients suffering from chronic cardio-pulmonary diseases commonly experience acute respiratory failure. As in younger patients, a well-known therapeutic approach of noninvasive mechanical ventilation is able to prevent orotracheal intubation in a large number of severe scenarios in elderly patients. In addition, this type of ventilation is frequently applied in elderly patients who refuse intubation for invasive mechanical ventilation. The rate of failure of noninvasive ventilation may be reduced by means of the integration of new technological devices (i.e., high-flow nasal cannula, extracorporeal CO₂ removal, cough assistance and high-frequency chest wall oscillation, and fiberoptic bronchoscopy). Ethical issues with end-of-life decisions and the choice of the environment are not clearly defined in the treatment of elderly with acute respiratory insufficiency.

Stroke Classification: Critical Role of Unusually Large von Willebrand Factor Multimers and Tissue Factor on Clinical Phenotypes Based on Novel "Two-Path Unifying Theory" of Hemostasis

Stroke is a hemostatic disease associated with thrombosis/hemorrhage caused by intracranial vascular injury with spectrum of clinical phenotypes and variable prognostic outcomes. The genesis of different phenotypes of stroke is poorly understood due to our incomplete understanding of hemostasis and thrombosis. These shortcomings have handicapped properly recognizing each specific stroke syndrome and contributed to controversy in selecting therapeutic agents. Treatment recommendation for stroke syndromes has been exclusively derived from the result of laborious and expensive clinical trials. According to newly proposed "two-path unifying theory" of in vivo hemostasis, intracranial vascular injury would yield several unique stroke syndromes triggered by 3 distinctly different thrombogenetic mechanisms depending upon level of intracranial intravascular injury and character of formed blood clots. Five major phenotypes of stroke occur via thrombogenetic paths: (1) transient ischemic attack due to focal endothelial damage limited to endothelial cells (ECs), (2) acute ischemic stroke due to localized ECs and subendothelial tissue (SET) damage extending up to the outer vascular wall, (3) thrombo-hemorrhagic stroke due to localized vascular damage involving ECs and SET and extending beyond SET to extravascular tissue, (4) acute hemorrhagic stroke due to major localized intracranial hemorrhage/hematoma into the brain tissue or space between the coverings of the brain associated with vascular anomaly or obtuse trauma, and (5) encephalopathic stroke due to disseminated endotheliopathy leading to microthrombosis within the brain. New classification of stroke phenotypes would assist in selecting rational therapeutic regimen for each stroke syndrome and designing clinical trials to improve clinical outcome.

Bispectral index in hypercapnic encephalopathy associated with COPD exacerbation: a pilot study

BACKGROUND

Hypercapnic encephalopathy is relatively frequent in severe exacerbations of COPD (ECOPDs), with its intensity usually being evaluated through clinical scales. Bispectral index (BIS) is a relatively new technique, based on the analysis of the electroencephalographic signal, which provides a good approximation to the level of consciousness, having already been validated in anesthesia.

OBJECTIVE

The objective of the study was to evaluate the utility of BIS in the assessment of the intensity of hypercapnic encephalopathy in ECOPD patients.

PATIENTS AND METHODS

A total of ten ECOPD patients were included, and the level of brain activity was assessed using BIS and different scales: Glasgow Coma Scale, Ramsay Sedation Scale (RSS), and Richmond Agitation-Sedation Scale. The evaluation was performed both in the acute phase and 3 months after discharge.

RESULTS

BIS was recorded for a total of about 600 minutes. During ECOPD, BIS values ranged from 58.8 (95% CI: 48.6-69) for RSS score of 4 to 92.2 (95% CI: 90.1-94.3) for RSS score of 2. A significant correlation was observed between values obtained with BIS and those from the three scales, although the best fit was for RSS, followed by Glasgow and Richmond (r=-0.757, r=0.701, and r=0.615, respectively; P<0.001 for all). In the stable phase after discharge, BIS showed values considered as normal for a wake state (94.6; 95% CI: 91.7-97.9).

CONCLUSION

BIS may be useful for the objective early detection and automatic monitoring of the intensity of hypercapnic encephalopathy in ECOPD, facilitating the early detection and follow-up of this condition, which may avoid management problems in these patients.

Acidic Preconditioning Protects Against Ischemia-Reperfusion Lung Injury Via Inhibiting the Expression of Matrix Metalloproteinase 9

BACKGROUND

Acidic preconditioning (APC) has been demonstrated to protect against ischemia-reperfusion (IR)-induced lung injury, which could occur during lung transplantation or cardiopulmonary bypass. However, the pathophysiological mechanisms underlying IR lung injury and APC protection are not completely understood. The key factors responsible for the protective effects of APC are not clear. In this study, bioinformatics was used to predict the potential key factor in IR lung injury and explore the important mediator of the APC protective effect in IR lung injury.

METHODS

First, we screened GSE6730, which is related to both lung injury and IR in Gene Expression Omnibus, and STRING was used later to select the genes in GSE6730 needed in the future. Animal models were established and classified to validate the effect of matrix metalloproteinase 9 (MMP-9) on lung injury after IR by adding a selective inhibitor (4-phenoxyphenylsulfonyl) methylthiirane, MMP-9 inhibitor. Next, for better understanding of APC inhibition of the expression of MMP-9 in lung injury, assessment of lung tissues, Western blot analysis, and RNA extraction and reverse transcription quantitative polymerase chain reaction were conducted.

RESULTS

MMP-9 was identified to be overexpressed after IR according to the analysis on GSE67370. MMP-9 was an unknown gene in relation to acute lung injury and found to be associated with interleukin (IL)-1B, IL-6, and IL-8. The expressions of these inflammatory factors, including MMP-9, were all elevated in IR. Furthermore, lung injury was ameliorated, and the level of MMP-9 was lower when an MMP-9 inhibitor, (4-phenoxyphenylsulfonyl) methylthiirane, was added. Compared with group IR, APC reversed the ischemia-induced lung injury, and the level of MMP-9 was lower, and the concentrations of IL-1β, IL-6, and IL-8 were decreased.

CONCLUSIONS

Our findings reveal a novel mechanism indicating that IR induces higher expression of MMP-9 in lung injury by increasing the expression of inflammation-related factors. APC might protect against IR lung injury by inhibiting the expression of MMP-9.

Early use of noninvasive techniques for clearing respiratory secretions during noninvasive positive-pressure ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease and hypercapnic encephalopathy: A prospective cohort study

Noninvasive positive-pressure ventilation (NPPV) might be superior to conventional mechanical ventilation (CMV) in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPDs). Inefficient clearance of respiratory secretions provokes NPPV failure in patients with hypercapnic encephalopathy (HE). This study compared CMV and NPPV combined with a noninvasive strategy for clearing secretions in HE and AECOPD patients.The present study is a prospective cohort study of AECOPD and HE patients enrolled between October 2013 and August 2015 in a critical care unit of a major university teaching hospital in China.A total of 74 patients received NPPV and 90 patients received CMV. Inclusion criteria included the following: physician-diagnosed AECOPD, spontaneous airway clearance of excessive secretions, arterial blood gas analysis requiring intensive care, moderate-to-severe dyspnea, and a Kelly-Matthay scale score of 3 to 5. Exclusion criteria included the following: preexisting psychiatric/neurological disorders unrelated to HE, upper gastrointestinal bleeding, upper airway obstruction, acute coronary syndromes, preadmission tracheostomy or endotracheal intubation, and urgent endotracheal intubation for cardiovascular, psychomotor agitation, or severe hemodynamic conditions.Intensive care unit participants were managed by NPPV. Participants received standard treatment consisting of controlled oxygen therapy during NPPV-free periods; antibiotics, intravenous doxofylline, corticosteroids (e.g., salbutamol and ambroxol), and subcutaneous low-molecular-weight heparin; and therapy for comorbidities if necessary. Nasogastric tubes were inserted only in participants who developed gastric distension. No pharmacological sedation was administered.The primary and secondary outcome measures included comparative complication rates, durations of ventilation and hospitalization, number of invasive devices/patient, and in-hospital and 1-year mortality rates.Arterial blood gases and sensorium levels improved significantly within 2 hours in the NPPV group with lower hospital mortality, fewer complications and invasive devices/patient, and superior weaning off mechanical ventilation. Mechanical ventilation duration, hospital stay, or 1-year mortality was similar between groups.NPPV combined with a noninvasive strategy to clear secretions during the first 2 hours may offer advantages over CMV in treating AECOPD patients complicated by HE.

Challenges on non-invasive ventilation to treat acute respiratory failure in the elderly

Acute respiratory failure is a frequent complication in elderly patients especially if suffering from chronic cardio-pulmonary diseases. Non-invasive mechanical ventilation constitutes a successful therapeutic tool in the elderly as, like in younger patients, it is able to prevent endotracheal intubation in a wide range of acute conditions; moreover, this ventilator technique is largely applied in the elderly in whom invasive mechanical ventilation is considered not appropriated. Furthermore, the integration of new technological devices, ethical issues and environment of treatment are still largely debated in the treatment of acute respiratory failure in the elderly.

This review aims at reporting and critically analyzing the peculiarities in the management of acute respiratory failure in elderly people, the role of noninvasive mechanical ventilation, the potential advantages of applying alternative or integrated therapeutic tools (i.e. high-flow nasal cannula oxygen therapy, non-invasive and invasive cough assist devices and low-flow carbon-dioxide extracorporeal systems), drawbacks in physician’s communication and “end of life” decisions. As several areas of this topic are not supported by evidence-based data, this report takes in account also “real-life” data as well as author’s experience.

The choice of the setting and of the timing of non-invasive mechanical ventilation in elderly people with advanced cardiopulmonary disease should be carefully evaluated together with the chance of using integrated or alternative supportive devices. Last but not least, economic and ethical issues may often challenges the behavior of the physicians towards elderly people who are hospitalized for acute respiratory failure at the end stage of their cardiopulmonary and neoplastic diseases.

Successful management of acute respiratory failure with noninvasive mechanical ventilation after drowning, in an epileptic-patient

Sea drowning is a common cause of accidental death worldwide. Respiratory complications such as acute pulmonary oedema, which is often complicated by acute respiratory distress syndrome, is often seen. Noninvasive ventilation is already widely used as a first approach to treat acute respiratory failure resulting from multiple diseases. We report a case of a 45 year old man with a history of epilepsy, motor and mental handicap who developed acute respiratory failure secondary to sea water drowning after an epileptic crisis. We illustrate successful and rapid management of this case with noninvasive ventilation. We emphasize the advantages and limitations of using noninvasive ventilation to treat acute respiratory failure due to sea water drowning syndrome.

Mechanical ventilation in patients with chronic obstructive pulmonary disease and bronchial asthma

Chronic obstructive pulmonary disease (COPD) and bronchial asthma often complicate the surgical patients, leading to post-operative morbidity and mortality. Many authors have tried to predict post-operative pulmonary complications but not specifically in COPD. The aim of this review is to provide recent evidence-based guidelines regarding predictors and ventilatory strategies for mechanical ventilation in COPD and bronchial asthma patients. Using Google search for indexing databases, a search for articles published was performed using various combinations of the following search terms: ‘Predictors’; ‘mechanical ventilation’; COPD’; ‘COPD’; ‘bronchial asthma’; ‘recent strategies’. Additional sources were also identified by exploring the primary reference list.

Safety and efficacy of dexmedetomidine for long-term sedation in critically ill patients

Purpose

We evaluated the safety and efficacy of long-term administration of dexmedetomidine in patients in the intensive care unit (ICU). Primary endpoint was the incidence of hypotension, hypertension, and bradycardia. Secondary endpoints were withdrawal symptoms, rebound effects, the duration of sedation with Richmond Agitation-Sedation Scale (RASS) ≤ 0 relative to the total infusion time of dexmedetomidine, and the dose of additional sedatives or analgesics.

Methods

Dexmedetomidine 0.2–0.7 μg/kg/h was continuously infused for maintaining RASS ≤ 0 in patients requiring sedation in the ICU. Safety and efficacy of short-term (≤24 h) and long-term (>24 h) dexmedetomidine administration were compared.

Results

Seventy-five surgical and medical ICU patients were administered dexmedetomidine. The incidence of hypotension, hypertension, and bradycardia that occurred after 24 h (long-term) was not significantly different from that occurring within 24 h (short-term) (P = 0.546, 0.513, and 0.486, respectively). Regarding withdrawal symptoms, one event each of hypertension and headache occurred after the end of infusion, but both were mild in severity. Increases of mean arterial blood pressure and heart rate after terminating the infusion of dexmedetomidine were not associated with the increasing duration of its infusion. The ratio of duration with RASS ≤ 0 was ≥ 85 % until day 20, except day 9 (70 %) and day 10 (75 %). There was no increase in the dose of additional sedatives or analgesics after the first 24-h treatment period.

Conclusions

Long-term safety of dexmedetomidine compared to its use for 24 h was confirmed. Dexmedetomidine was useful to maintain an adequate sedation level (RASS ≤ 0) during long-term infusion.

Respiratory High-Dependency Care Units for the burden of acute respiratory failure

The burden of acute respiratory failure (ARF) has become one of the greatest epidemiological challenges for the modern health systems. Consistently, the imbalance between the increasing prevalence of acutely de-compensated respiratory diseases and the shortage of high-daily cost ICU beds has stimulated new health cost-effective solutions. Respiratory High-Dependency Care Units (RHDCU) provide a specialised environment for patients who require an "intermediate" level of care between the ICU and the ward, where non-invasive monitoring and assisted ventilation techniques are preferentially applied. Since they are dedicated to the management of "mono-organ" decompensations, treatment of ARF patients in RHDCU avoids the dangerous "under-assistance" in the ward and unnecessary "over-assistance" in ICU. RHDCUs provide a specialised quality of care for ARF with health resources optimisation and their spread throughout health systems has been driven by their high-level of expertise in non-invasive ventilation (NIV), weaning from invasive ventilation, tracheostomy care, and discharging planning for ventilator-dependent patients.