Current Respiratory Medicine Reviews - Volume 10, Issue 3, 2014

Retention of airway secretions is highly common in critically ill patients, on mechanical ventilation (MV). The endotracheal tube (ETT) plays a critical role in this context; indeed, upon inflation of the ETT cuff, mucociliary transport drastically impairs. Additionally, patients with neurological impairments or underlying diseases, i.e. asthma, chronic obstructive pulmonary disease, cystic fibrosis and non-cystic fibrosis bronchiectasis are at the greatest risk. Indeed, in these patients, MV rapidly disrupts the balance between overproduction of mucus and impaired clearance capabilities. Importantly, during MV, mechanically ventilated patients are positioned in the semi recumbent position and several laboratory studies suggested that in this position retained mucus might move toward the distal airways, driven by gravity. Additionally, airflow promotes clearance or retention of retained mucus, via a two-phase gas-liquid flow mechanism. In sedated, invasively ventilated patients, the inspiratory flow can be modulated through the ventilatory settings, and theoretically, mucus clearance could be promoted or hindered through adjustments of the ventilatory settings. Yet, these assumptions should be corroborated in large translational clinical trials. Importantly, humidification of respiratory gases plays an essential role in maintaining mucus clearance rate within the physiologic range. Thus, the most appropriate humidifier should be chosen on a case-by-case basis, and given the reported poor performance of heat-moisture exchanger during ventilation at high minute volumes, heated humidifiers should be a primary choice for patients requiring high ventilatory support. Finally, numerous drugs, commonly used in ventilated patients, i.e. oxygen, inhaled anesthetics, narcotics profoundly affect mucociliary clearance and increase mucus retention.

Intubation, mechanical ventilation and subsequent immobilization, sedation and drying of airways predisposes to retained secretions. This can lead to a number of complications including endotracheal tube occlusion, ventilator associated infection, hemodynamic compromise and life threatening hypoxemia. Identification of retained secretions can be difficult with a poor specificity for many components of the examination. Ideally, it is important to have a high confidence in the methods of detecting airways secretions in order to be able to effectively manage them in order to prevent an emergent situation developing. The various components of examination including auscultation, oxygenation status, radiology, pulmonary mechanics and waveform analysis are discussed together with validity and repeatability information. Two of the most promising areas for accurate bedside localization of secretions are auscultation and waveform analysis.

Secretion retention in the intubated and mechanically ventilated patient has been poorly described and investigated to date. There is no gold standard for the diagnosis or detection of secretion retention in the intubated and mechanically ventilated patient. Hence, the impact of secretion retention on patient outcomes is unknown and driven by either anecdote or opinion or by the use of surrogate measures. Surrogate measures such as the increased need for airway suctioning have been related to the increased re-intubation rates after elective extubation. In the intubated and mechanically ventilated patient secretion retention may impact on gas exchange, pulmonary complications such as atelectasis or pneumonia, endotracheal tube occlusion, need for change of artificial airway or therapeutic bronchoscopy or chest physiotherapy. Factors such as mucus volume, mucus viscosity, mucus depth, mucus location (peripheralised versus centralized secretions), patient factors (e.g. inspiratory and or expiratory muscle strength, pre-existing diseases such as COPD or neuromuscular disorders), and the interplay with intubation and mechanical ventilation or the combination thereof may determine whether patient outcomes are affected. In the intubated and mechanically ventilated patient the difficulties in the detection and monitoring the movement of secretions within the airways pose the greatest challenge to identifying the clinical impact and hence optimal methods to facilitate secretion clearance. This article will review the literature on secretion retention and patient outcomes in the intubated and mechanically ventilated patient.

Secretion retention is common in critically ill patients who are intubated and mechanically ventilated. Due to the presence of an artificial airway, sedation and analgesia and alterations in the physiological mechanism through which humidification of inspired air occurs, secretion clearance is often impaired in this cohort of patients, Therefore, a bundle of non-pharmacological strategies are routinely used to manage airway secretion retention. This review paper explores several preventative strategies used in the management of airway secretions, offering a clinical perspective on their use in patients who are intubated and mechanically ventilated, based on current literature. Furthermore, this article discusses several treatment modalities, including chest physiotherapy techniques, which may be employed clinically to manage secretion retention, and the efficacy surrounding such techniques.

Transbronchial needle aspiration biopsy (TBNA) was developed in the 1980’s as a technique for mediastinal and hilar lymph node biopsy. This offered pulmonologists and patients a minimally invasive technique for mediastinal non-small cell lung cancer staging and served as an alternative to surgical mediastinoscopy. Over the last few decades there are new additions to this technique using guided TBNA with endobronchial ultrasound (EBUS) and the use navigational bronchoscopy for peripheral lung TBNA. The future of TBNA may potentially transition from a diagnostic tool to a therapeutic instrument by locally injecting medications.

Background: Nocturnal blood pressure (NBP) abnormalities are often encountered in obstructive sleep apnea (OSA) patients. Both phenomena are associated with increased cardiovascular morbidity and mortality in general hypertensives. The aim of the study was to determine the prevalence of target organ damage (TOD) in different nighttime blood pressure patterns of newly diagnosed OSA patients with early hypertension. Materials and Methods: Seventy-four patients participated in the study. OSA was verified by a polysomnography. All patients had controlled hypertension. 24-hour BP monitoring divided participants into: 39 (NH) - nocturnal hypertensives; 18 NND - nocturnal normotensive dippers, (NBP fall>10%, NBP<120/70mmHg); 17 (NNN) - nocturnal normotensive non-dippers (NBP fall<10%, NBP<120/70mmHg). Anthropological glucometabolic and sleep study characteristics were collected. Cardiac damage (left ventricular mass index - LVMI, relative wall thickness - RWT) was assessed by a standard echocardiography; renal damage by microalbuminuria and vascular damage by ultrasonography of the carotid vessels. Results: Left ventricular hypertrophy (LVH) was met in 33% of the dippers, 64.7% of NNN and in 62.6% of NH. LVMI in non-dippers was higher when compared to dippers (127.71± 8.71 vs 109.1± 4.9g/m2, p=0.03) and nearly identical to those in patients with NH (127.71± 8.71 vs 124.18 ± 5.92g/m2, p=0.42). Microalbuminuria was present in 3% and 6% of dippers/non-dippers and in 51% of NH. IMT and RWT were within the same range in the three groups. Multivariate regression analysis showed that: LVMI correlated positively to age and sleep time at SaO2<90%; RWT correlated positively to BMI, age and AHI. IMT and microalbuminuria correlated to none of the parameters. Conclusion: In newly diagnosed OSA patients with early hypertension (duration <3 years) TOD was detected mostly at cardiac level. It was presented by an increased LVMI, that was associated with the age and the sleep time at SaO2<90%.

Background: Hypertensive obstructive sleep apnea (OSA) patients are more likely to have nocturnal blood pressure (NBP) abnormalities than hypertensives without it. The establishment of predictors of NBP abnormalities would be of clinical significance. Aim: To determine the role of anthropometric, glucometabolic and sleep study parameters in the detection of OSA patients with NBP abnormalities. Materials and Methods: Eighty-seven patients with newly diagnosed OSA and hypertension participated in the study. OSA was verified by a polysomnography. An ambulatory 24-hour BP monitoring was done to discern (NH) - nocturnal hypertensives (NBP >120/70mmHg) from (NN) - nocturnal normotensives. Results: Risk factors of NH did not differ significantly from those in NN. From all the conventional cardiovascular risk factor parameters only the duration of sleep at SaO2<90% was significantly longer in NH ( p=0.009), as well as, the levels of HbA1C (p=0.024). After adjustment for confounding factors in a multiple regression model only the time of sleep at SaO2<90% remained as an independent predictor. HbA1C levels were of borderline significance. Conclusion: The time of sleep at SaO2 <90%may be applied for the detection of NBP abnormalities in severe OSA patients.