[Non-invasive mechanical ventilation in acute respiratory failure]

[Ermergency diagnostics and therapeutic management of acute dyspnea]

This article presents the relevant diagnostic examinations and principles for the initial management of acute dyspnea in detail. The emergency physician must work through broad differential diagnostic considerations while providing appropriate initial treatment for a potentially life-threatening disease. The airway, breathing and circulation are the primary focus for the emergency physician when beginning emergency management. As soon as these are stabilized, further clinical investigations and treatment can be continued. The appropriate place for further treatment is determined by risk stratification.

Pneumologie

Die Pneumologie und Beatmungsmedizin gehört zur Basis der Intensivmedizin. Die Abklärung der Dyspnoe, das Management des Asthma bronchiale, der akuten COPD-Exazerbation und des akuten Lungenversagens (ARDS) bilden die Säulen dieses Kapitels. Im Rahmen der bettseitigen Abklärung der Dyspnoe gewinnt die Lungen- bzw. Thoraxsonographie zunehmend an Bedeutung.

[Non-invasive and invasive out of hospital ventilation in chronic respiratory failure : Consensus report of the working group on ventilation and intensive care medicine of the Austrian Society of Pneumology]

The current consensus report was compiled under the patronage of the Austrian Society of Pneumology (Österreichischen Gesellschaft für Pneumologie, ÖGP) with the intention of providing practical guidelines for out-of-hospital ventilation that are in accordance with specific Austrian framework parameters and legal foundations. The guidelines are oriented toward a 2004 consensus ÖGP recommendation concerning the setup of long-term ventilated patients and the 2010 German Respiratory Society S2 guidelines on noninvasive and invasive ventilation of chronic respiratory insufficiency, adapted to national experiences and updated according to recent literature. In 11 chapters, the initiation, adjustment, and monitoring of out-of-hospital ventilation is described, as is the technical equipment and airway access. Additionally, the different indications-such as chronic obstructive pulmonary diseases, thoracic restrictive and neuromuscular diseases, obesity hypoventilation syndrome, and pediatric diseases-are discussed. Furthermore, the respiratory physiotherapy of adults and children on invasive and noninvasive long-term ventilation is addressed in detail.

[Acute cardiorenal syndromes]

Heart and kidney are closely interacting organs which function interdependently. Organ crosstalk between these two organs is based on humoral regulation and by inflammatory mediators, which are similar to those dominating systemic inflammation syndrome. The close interaction between heart and kidney results in organ dysfunction following both chronic and acute functional impairment of the respective counterpart. These changes are summarized under the term cardiorenal syndrome (CRS) which is subdivided into 5 types. In the setting of emergency medicine and intensive care units, CRS types 1 and 3 are the most common. CRS type 1 is characterized by acute kidney injury (AKI) developing as a consequence of acute heart failure. CRS type 3 is represented by acute cardiac failure following AKI, often occurring as a consequence of nephrotoxins. Diagnosis of CRS should preferably be made on basis of the Kidney Disease: Improving Global Outcomes (KDIGO) criteria for the diagnosis and staging of AKI. The cardiac diagnostic workup should include echocardiography, electrocardiogram (ECG), cardiac enzymes, and brain natriuretic peptide (BNP). The therapeutic approach in CRS is primarily aimed at treating the causative organ dysfunction. In case of CRS type 3 this means ensuring adequate kidney perfusion, cautious fluid management, and avoiding additional nephrotoxins. In case of diuretic resistant fluid overload, early initiation of extracorporeal fluid removal, preferably by renal replacement therapy, should be considered.

[Acute on chronic respiratory failure in interstitial pneumonias]

BACKGROUND

Acute exacerbations of idiopathic interstitial pneumonias and exacerbations of pleuropulmonary disease in connective tissue diseases are associated with a high mortality.

DIAGNOSTIC PROCEDURES

They have to be differentiated from respiratory failure in patients with interstitial lung disease as a result of infections, pulmonary embolism, cardiac failure and drug toxicity, because the latter can be treated causally. The extent and the invasivity of diagnostic procedures have to be adopted to the patient's situation. A rapid diagnosis is important in order to initiate therapies (antibiotics, anticoagulation, immunosuppression) in treatable causes of exacerbations.

IMPORTANCE OF VENTILATION

The prognosis for patients who are under invasive mechanical ventilation in acute exacerbations of interstitial lung disease is poor. Especially in acute exacerbations of idiopathic pulmonary fibrosis (IPF), there is no general recommendation for either invasive or for noninvasive ventilation. In acute exacerbations of other subtypes of interstitial pneumonia, either idiopathic or as a pulmonary manifestation of connective tissue disease, and in all secondary exacerbations of idiopathic interstitial pneumonias which offer further treatment options, the decision about mechanical ventilation requires a differentiated assessment.

LUNG TRANSPLANTATION

In younger patients with interstitial lung disease and a progressive disease, indication for lung transplantation should be made early and before an exacerbation. If patients listed for lung transplantation experience an acute exacerbation, bridging-to-transplant has to be discussed with the transplant unit. In cases without further causal treatment options palliative care must be initiated.

[Noninvasive ventilation in patients with persistent hypercapnia]

BACKGROUND

Chronic respiratory failure is caused by insufficiency of the inspiratory muscles, i.e. mainly the diaphragm, which represents the so-called "respiratory pump". Insufficiency of the respiratory pump causes hypercapnia.

THERAPEUTIC INTERVENTION

Diseases with chronic hypercapnia are characterized by reduced survival. Mechanical ventilation-mostly applied as noninvasive mechanical ventilation (NIV)-improves ventilation and unloads the inspiratory muscles.

INDICATION

Strong evidence supports the use of domiciliary NIV already in mild degrees of chronic respiratory failure caused by neuromuscular diseases, thoracic restrictions and obesity hypoventilation. In these diseases long-term NIV improves both physiological parameters (such as blood gases) and clinical outcome, e.g. exercise capacity, right heart dysfunction, sleep quality, disease-specific aspects of health-related quality of life (HRQL) and survival rate. In contrast, its influence on long-term survival in chronic obstructive pulmonary disease (COPD) patients is not clearly proven. Prescription of home NIV in COPD should therefore be restricted to severe degrees of chronic respiratory failure. Finally, there is an indication for domiciliary NIV in patients after prolonged weaning from mechanical ventilation. This paper elaborates underlying pathophysiology, diseases and how NIV works in chronic hypercapnic respiratory failure.

Noninvasive Mechanical Ventilation Guidelines and Standard Protocols for Noninvasive Mechanical Ventilation in Patients with High-Risk Infections

Noninvasive ventilation (NIV) is associated with lower rates of endotracheal intubation and decreased mortality in patients with acute respiratory failure. Therefore, NIV should be preferred to invasive ventilation whenever possible [1]. In clinical settings, most of the patients were treated by NIV because of pulmonary edema or exacerbated chronic obstructive lung disease (COPD) [2]. With endemic and high-risk infection, most of the critically ill patients develop acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS). Furthermore, NIV, an “aerosol-producing factor” might be regarded as a high-risk procedure for medical staff [3].

[Ventilation strategies for chronic obstructive pulmonary disease]

Chronic obstructive pulmonary disease (COPD) is considered to be one of the most frequent pulmonary diseases in industrialized countries. Non-invasive ventilation (NIV) is the first choice therapy in acute exacerbations of chronic hypercapnic respiratory failure (AE-COPD). Effective delivery of NIV requires a specialized interdisciplinary team with sufficient monitoring. NIV is delivered as assisted positive pressure ventilation where high inspiratory flow and peak pressure are required. The external positive end expiratory pressure (PEEP) should be adjusted to the intrinsic PEEP. Criteria of success are improvement in the clinical, especially neurological condition as well as improvement of pH and PaCO(2). Patients with a pH between 7.25 and 7.35 have demonstrated most benefit from NIV. In cases of patients not responding to NIV endotracheal intubation should be initiated in a timely manner. Assisted ventilation modes are preferred over controlled ventilation modes in intubated COPD patients. Settings of respirators have to be aimed at a reduction of intrinsic PEEP and dynamic hyperinflation. This includes sufficient external PEEP, long expiration times and low respiratory frequencies even allowing for permissive hypercapnia.

[Preventable mistakes during endotracheal intubation. Overview and concepts]

Endotracheal intubation is a standard procedure in anesthesiology as well as in intensive care medicine in many forms of assisted spontaneous breathing or controlled ventilation. In addition it continues to be the gold standard for airway protection in prehospital and in-hospital emergency medicine settings. Approaches will have to be considered to help prevent errors before they occur not only in the non-elective use of endotracheal intubation. The most common preventable situations are summarized in this paper.

[Difficult extubation]

Optimal timing of extubation following intubation substantially impacts on the prognosis of intensive care unit (ICU) patients whereby both early extubation with the risk of reintubation and delayed extubation with prolongation of mechanical ventilation need to be avoided. In most cases extubation is easy; in some cases, however, extubation may be extremely difficult or even impossible with two major reasons being responsible for this: firstly, laryngeal edema, where the cuff leak test and steroid treatment are well established procedures aimed at diagnosing and treating potential laryngeal complications and secondly, the presence of (chronic) respiratory failure despite sufficient treatment of acute respiratory failure. This can result in post-extubation failure following extubation or weaning failure and noninvasive ventilation has been increasingly used in both scenarios. Currently, specialised weaning centres are being established and certified in Germany aimed at managing the complex tasks for patients with prolonged weaning.

[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.

Short term non-invasive ventilation post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery - a randomized controlled trial

BACKGROUND

In the immediate postoperative period, obese patients are more likely to exhibit hypoxaemia due to atelectasis and impaired respiratory mechanics, changes which can be attenuated by non-invasive ventilation (NIV). The aim of the study was to evaluate the duration of any effects of early initiation of short term pressure support NIV vs. traditional oxygen delivery via venturi mask in obese patients during their stay in the PACU.

METHODS

After ethics committee approval and informed consent, we prospectively studied 60 obese patients (BMI 30-45) undergoing minor peripheral surgery. Half were randomly assigned to receive short term NIV during their PACU stay, while the others received routine treatment (supplemental oxygen via venturi mask). Premedication, general anaesthesia and respiratory settings were standardized. We measured arterial oxygen saturation by pulse oximetry and blood gas analysis on air breathing. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 1 h, 2 h, 6 h and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05.

RESULTS

There were no differences at the first assessment. During the PACU stay, pulmonary function in the NIV group was significantly better than in the controls (p < 0.0001). Blood gases and the alveolar to arterial oxygen partial pressure difference were also better (p < 0.03), but with the addition that overall improvements are of questionable clinical relevance. These effects persisted for at least 24 hours after surgery (p < 0.05).

CONCLUSION

Early initiation of short term NIV during in the PACU promotes more rapid recovery of postoperative lung function and oxygenation in the obese. The effect lasted 24 hours after discontinuation of NIV. Patient selection is necessary in order to establish clinically relevant improvements. TRIAL REGISTRATION#: DRKS00000751; http://www.germanctr.de.

[Bronchial asthma and chronic obstructive pulmonary disease with acute exacerbation: preclinical differential diagnostic and emergency treatment]

Chronic obstructive pulmonary disease (COPD) and bronchial asthma are the most common causes of obstructive pulmonary diseases and acute dyspnoea. In the preclinical emergency situation a distinction between bronchial asthma and exacerbated COPD is difficult because symptoms are similar. Although the preclinical measures differ only marginally, a differential diagnosis from other causes of respiratory obstruction and acute dyspnoea, such as cardiac decompensation, anaphylaxis, aspiration of foreign bodies, tension pneumothorax and inhalation trauma is necessary because alternative treatment options are required. In the treatment of COPD and bronchial asthma inhalative bronchodilatory beta(2)-mimetics are the first choice especially for serious obstructive emergencies because there is an unfavorable relationship between effect and side-effects for the intravenous route. Dosable aerosols, nebulization and if necessary, continuous nebulization, are appropriate application forms even for serious obstructive crises with the need of a respirator. In these cases a minimal inspiratory flow in patients is not required. Theophylline only plays a minor role to beta(2)-mimetics and anticholinergics as a bronchodilator in asthma and COPD guidelines, even in serious obstructive diseases. For severe asthma attacks the administration of magnesium is a possible additional option. Systemic intravenous administration of steroids has an anti-inflammatory effect and for this reason is the second column of treatment for both diseases. Invasive ventilation remains a last resort to ensure respiratory function and indications for this are given in patients with clinical signs of impending exhaustion of breathing.