Christos Dragoumanis

Ventilator-associated Pneumonia or Endotracheal Tube-associated Pneumonia?An Approach to the Pathogenesis and Preventive Strategies Emphasizing the Importance of Endotracheal Tube

Ventilator-associated pneumonia is the most common nosocomial infection in the intensive care unit, and it is associated with prolonged hospitalization, increased health care costs, and high attributable mortality. During the past several decades, numerous studies focused on the crucial role of the endotracheal tube (ETT) in the pathogenesis of ventilator-associated pneumonia. Tracheal intubation thwarts the cough reflex, compromises mucocilliary clearance, injures the tracheal epithelial surface, provides a direct conduit for rapid access of bacteria from upper into the lower respiratory tract, and allows the formation of biofilm on the ETT surface. The combination of these factors puts the mechanically ventilated patient at great jeopardy of developing ventilator-associated pneumonia. Many preventive strategies have arisen from this understanding: control of intracuff pressure, aspiration of subglottic secretions, decontamination of subglottic area, use of antiseptic impregnated ETTs, and elimination or prevention of the ETT biofilm formation. The authors review the role of ETT management for the prevention of the ventilator-associated pneumonia.

Prophylactic intravenous ondansetron and dolasetron in intrathecal morphine-induced pruritus: a randomized, double-blinded, placebo-controlled study.

Pruritus is the most common side effect of intrathecal morphine for postoperative pain relief. Activation of central 5-hydroxytryptamine subtype 3 (5-HT3) receptors is one of its possible mechanisms. The role of 5-HT3 antagonists in the prevention of pruritus has not been clearly established. In a prospective, randomized, double-blind, placebo-controlled study, we evaluated the efficacy of prophylactic administration of ondansetron and dolasetron for the prevention of intrathecal morphine-induced pruritus. The patients were randomized into 3 groups to receive either 4 mg ondansetron IV (group O, n = 35), 12.5 mg dolasetron IV (group D, n = 35) or 5 mL placebo (group P, n = 35) 30 min before administration of spinal anesthesia with 10 to 17.5 mg of 0.5% hyperbaric bupivacaine and 0.25 mg of morphine for urologic, orthopedic, or vascular surgery. Patients were evaluated for incidence and severity of pruritus at arrival to the postanesthesia care unit and at 2, 4, 8, and 24 h postoperatively. The incidence and severity of pruritus was significantly less frequent in the ondansetron and dolasetron groups compared with placebo (34%, 20%, and 66% respectively, P < 0.01). Patients who received 5-HT3 antagonist reported significantly less total severity of pruritus compared with placebo during the first 8 h and the severe pruritus was observed only in patients within P group (P group: 4 of 35; 11%, O or D group: 0 of 35; 0%, P < 0.05). We conclude that the prophylactic use of ondansetron and dolasetron helps to reduce the incidence and severity of intrathecal morphine-induced pruritus.

Relation of heart rate variability to serum levels of C-reactive protein, interleukin 6, and 10 in patients with sepsis and septic shock

PURPOSE The aim of the study was to investigate possible associations between different heart rate variability (HRV) indices and various biomarkers of inflammation in 45 septic patients. MATERIALS AND METHODS We daily assessed HRV in the time domain (SD of RR intervals [SDNN]), frequency domain (low [LF], high frequency [HF], LF/HF as an indicator of sympathovagal balance); the 2 values of SD (SD1, SD2) from the Poincaré plot; and measured C-reactive protein, interleukin 6, and interleukin 10 serum levels in patients with sepsis and mean Sequential Organ Failure Assessment score (SOFA) 10 or lower (n = 25) and septic shock (SOFA > 10, n = 20) for 6 days. RESULTS C-reactive protein exhibited significant negative correlations with LF (r = -0.78), LF/HF (r = -0.61), and SDNN (r = -0.79) and positive correlations with HF (r = 0.80) and SD1/SD2 (r = 0.66), whereas interleukin 10 was positively correlated with HF (r = 0.71) and negatively with LF (r = -0.89) and LF/HF (r = -0.66) in septic shock patients (P < .05 for all comparisons). Standard deviation of RR intervals and HF proved to be independent predictors of the severity of disease (beta slope [B] = -1.091; P = .013; 95% confidence interval [CI], -1.43 to -0.74, and B = 0.78; P = .022; 95% CI, 0.21-1.35, respectively). CONCLUSIONS Our data suggest that low HRV and sympathovagal balance during septic shock are associated with both an increased hyperinflammatory and antiinflammatory response.

Changes of heart and respiratory rate dynamics during weaning from mechanical ventilation: A study of physiologic complexity in surgical critically ill patients

PURPOSE The aim of the study was to investigate heart rate (HR) and respiratory rate (RR) complexity in patients with weaning failure or success, using both linear and nonlinear techniques. MATERIALS AND METHODS Forty-two surgical patients were enrolled in the study. There were 24 who passed and 18 who failed a weaning trial. Signals were analyzed for 10 minutes during 2 phases: (1) pressure support (PS) ventilation (15-20 cm H(2)O) and (2) weaning trials with PS (5 cm H(2)O). Low- and high-frequency (LF, HF) components of HR signals, HR multiscale entropy (MSE), RR sample entropy, cross-sample entropy between cardiorespiratory signals, Poincaré plots, and α1 exponent were computed in all patients and during the 2 phases of PS. RESULTS Weaning failure patients exhibited significantly decreased RR sample entropy, LF, HF, and α1 exponent, compared with weaning success subjects (P < .001). Their changes were opposite between the 2 phases, except for MSE that increased between and within groups (P < .001). A new model including rapid shallow breathing index (RSBI), α1 exponent, RR, and cross-sample entropies predicted better weaning outcome compared with RSBI, airway occlusion pressure at 0.1 second (P(0.1)), and RSBI × P(0.1) (conventional model, R(2) = 0.887 vs 0.463; P < .001). Areas under the curve were 0.92 vs 0.86, respectively (P < .005). CONCLUSIONS We suggest that nonlinear analysis of cardiorespiratory dynamics has increased prognostic impact upon weaning outcome in surgical patients.

Negative-pressure acute tracheobronchial hemorrhage and pulmonary edema

Negative-pressure pulmonary edema is a well-known complication of an acute upper airway obstruction, which may rarely present as acute alveolar hemorrhage in cases of severe capillary stress failure. Hemorrhage from the central airways has also been reported as a rare manifestation of acute tracheobronchial injury, associated with severe disruption of the bronchial vasculature due to highly negative inspiratory pressure. In this clinical report, we describe a case of both acute tracheobronchial and alveolar hemorrhage in a young man, occurring immediately after extubation due to laryngospasm, diagnosed by bronchoscopy with bronchoalveolar lavage (BAL), measurement of the pulmonary edema fluid/plasma protein ratio, and by thoracic computed tomography (CT) scan. We propose that the patient experienced severe postobstructive negative-pressure pulmonary edema, related to increased permeability of the alveolar capillary membrane and a parallel loss of integrity of the bronchial vascular network. Our findings suggest that both changes in the bronchial circulation and mechanical stress failure of the more distal alveolar-capillary system may be induced by severe and acute upper-airway obstruction.

Biosignal analysis techniques for weaning outcome assessment

Discontinuation of mechanical ventilation in critically ill patients is a challenging task and involves a careful weighting of the benefits of early extubation and the risks of premature spontaneous breathing trial. Recently, apart from studying different physiological variables by means of descriptive statistical tests, breathing pattern variability analysis has been performed for the assessment of weaning readiness. A limited number of clinical studies implementing different weaning protocols in heterogeneous groups of patients and using a variable set of signal processing techniques have appeared in the critical care literature, with varying results. The purpose of this review article is 3-fold: (1) to describe the different signal processing techniques being implemented for the assessment of weaning readiness, (2) to provide insight into the pathophysiological mechanisms that may govern breath-to-breath variability/complexity in health and disease, and (3) to present results from the critical care literature derived from the application of biosignal analysis tools for the identification of possible weaning indices.

Apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical computed tomography pulmonary angiography.

Respiratory motion artifact in intubated and mechanically ventilated patients often reduces the quality of helical computed tomography pulmonary angiography (CTPA). Apneic oxygenation is a well established intra-operative technique that allows adequate oxygenation for short periods (up to 10 min) in sedated and paralyzed patients. We describe the use of the apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing CTPA.

A fatal case of recurrent amiodarone-induced thyrotoxicosis after percutaneous tracheotomy: a case report

BackgroundAmiodarone is a widely used antiarrythmic drug, which may produce secondary effects on the thyroid. In 14–18% of amiodarone-treated patients, there is overt thyroid dysfunction, usually in the form of amiodarone-induced thyrotoxicosis, which can be difficult to manage with standard medical treatment.Case presentationPresented is the case of a 65-year-old man, under chronic treatment of atrial fibrillation with amiodarone, who was admitted to the Intensive Care Unit with acute cardio-respiratory failure and fever. He was recently hospitalized with respiratory distress, attributed to amiodarone-induced pulmonary fibrosis. Clinical and laboratory investigation revealed thyrotoxicosis due to amiodarone treatment. He was begun on thionamide, prednisone and beta-blockers. After a short term improvement of his clinical status the patient underwent percutaneous tracheotomy due to weaning failure from mechanical ventilation, which led to the development of recurrent thyrotoxicosis, unresponsive to medical treatment. Finally, the patient developed multiple organ failure and died, seven days later.ConclusionWe suggest that percutaneous tracheotomy could precipitate a thyrotoxic crisis, particularly in non-euthyroid patients suffering from concurrent severe illness and should be performed only in parallel with emergency thyroid surgery, when indicated.

Can continuous oral suctioning with a saliva ejector in critically ill people be more effective

We congratulate Chow and colleagues (Chow et al., 2) on their work evaluating continuous oral suctioning S) as a preventive measure for ventilator-associated umonia (VAP). In their article Chow et al. (2012) show t implementation of COS using a saliva ejector in ically ill patients offers a new option for prevention of . Taking this opportunity, we would like to make some ments about this method of continuous oral suction. The main elements of VAP pathogenesis are the pharyngeal colonization of the critically ill patient h nosocomial pathogens, artificial ventilation through otracheal tube (ET), which interferes with natural ay protection mechanisms and the microaspirations of taminated oropharyngeal secretions (Zolfaghari and ncoll, 2011). Oropharyngeal secretions in the critically re made up of saliva and mucus from the nasal cavity rhinopharinx. The main component of these secretions aliva, produced mainly by the three major, paired vary glands of the oral cavity (the parotid, the mandibular, and the sublingual glands) and by 600– 0 minor salivary glands which line the oral cavity and pharynx, contributing only a small portion of total vary production. Saliva is produced continuously with ying rate (0.1–4 mL/min) depending on the degree of ulation (Despopoulos and Silbernagl, 2003). Normally retions produced by the mucosa of upper airway ities and the salivary glands are swallowed. When se secretions enter the lower airway they are expectod by activation of the cough reflex. In the intubated and ated critically ill patient the physiological mechanisms management of secretions are depressed or abolished sedation and presence of ET within the airway. sequently the oropharyngeal secretions are accumud by gravity into the lower (laryngeal) part of the rynx and then overflow into the subglottic space. The glottic space is sealed by the remaining tracheobronal tree by the inflated endotracheal tube (ET) cuff. Micro escapes around the cuff play a key role in pathogenesis of VAP (Seegobin and van Hasselt, 1986). Currently, in the critically ill intubated patients the manual oral suction, the drainage of the subglottic space and the sealing of the trachea by the endotracheal tube cuff are the three barriers against aspiration of secretions into the lower airway. Theoretically, if secretions were effectively removed from the oropharynx by suction they would never reach the subglottic space and subsequently could not be aspirated. Chow et al. (2012) performed COS in intubated critically ill patients using a device designated for suction during dental surgery, the saliva ejector (Orsing Hygoformic Saliva Ejector Adult Universal); spiral tubing, equipped with five holes at the inner rim of the spiral head for suction. A saliva ejector was connected to 100 mmHg of continuous suction for the drainage of saliva. The device was put between the patient’s cheek and teeth. When the patient changed position, the saliva ejector was placed on the dependent side to ensure better clearance of saliva. It seems logical to place the saliva ejector between the patient’s cheek and teeth as this is the site of the parotid duct: the outflow of the largest of the salivary glands – the parotid gland. However when placed close to the opening of the parotid duct, even in the dependent side, the saliva ejector is able to evacuate only one proportion of the total amount of the secretions of the upper airways, that produced by the one parotid gland. In the semi-recumbent body position the remaining oral secretions flow by gravity and accumulate in the laryngopharynx. These secretions subsequently overflow into the subglottic space and increase the risk of microaspirations. In our opinion an alternative and better position for the placement of a device for COS is the laryngopharynx, as this position is the lower part of pharynx and lies in front of the intubated glottis. Applying COS in this position could probably increase its effectiveness and improve the ability of this intervention to prevent VAP.

Changes of Heart and Respiratory Rate Dynamics During Weaning From Mechanical Ventilation: A Study of Physiologic Complexity in Surgical Critically Ill Patients

Purpose: The aim of the study was to investigate heart rate (HR) and respiratory rate (RR) complexity in patients with weaning failure or success, using both linear and nonlinear techniques. Materials and Methods: Forty-two surgical patients were enrolled in the study. There were 24 who passed and 18 who failed a weaning trial. Signals were analyzed for 10 minutes during 2 phases: (1) pressure support (PS) ventilation (15-20 cm H2O) and (2) weaning trials with PS (5 cm H2O). Low- and high-frequency (LF, HF) components of HR signals, HR multiscale entropy (MSE), RR sample entropy, cross-sample entropy between cardiorespiratory signals, Poincare plots, and α1 exponent were computed in all patients and during the 2 phases of PS. Results: Weaning failure patients exhibited significantly decreased RR sample entropy, LF, HF, and α1 exponent, compared with weaning success subjects (P b .001). Their changes were opposite between the 2 phases, except for MSE that increased between and within groups (P b .001). A new model including rapid shallow breathing index (RSBI), α1 exponent, RR, and cross-sample entropies predicted better weaning outcome compared with RSBI, airway occlusion pressure at 0.1 second (P0.1), and RSBI × P0.1 (conventional model, R 2 = 0.887 vs 0.463; P b .001). Areas under the curve were 0.92 vs 0.86, respectively (P b .005). Conclusions: We suggest that nonlinear analysis of cardiorespiratory dynamics has increased prognostic impact upon weaning outcome in surgical patients.