Ventilator Pressure Waveforms Research Articles

Transcutaneous electromyographic respiratory muscle recordings to quantify patient\u2013ventilator interaction in mechanically ventilated children

BackgroundTo explore the feasibility of transcutaneous electromyographic respiratory muscle recordings to automatically quantify the synchronicity of patient–ventilator interaction in the pediatric intensive care unit.MethodsProspective observational study in a tertiary paediatric intensive care unit in an university hospital. Spontaneous breathing mechanically ventilated children < 18 years of age were eligible for inclusion. Patients underwent a 5-min continuous recording of ventilator pressure waveforms and transcutaneous electromyographic signal of the diaphragm. To evaluate patient–ventilator interaction, the obtained neural inspiration and ventilator pressurization timings were used to calculate trigger and cycle-off errors of each breath. Calculated errors were displayed in the dEMG-phase scale.ResultsData of 23 patients were used for analysis. Based on the dEMG-phase scale, the median rates of synchronous, dyssynchronous and asynchronous breaths as classified by the automated analysis were 12.2% (1.9–33.8), 47.5% (36.3–63.1), and 28.9% (6.6–49.0).ConclusionsThe dEMG-phase scale quantifying patient–ventilator breath synchronicity was demonstrated to be feasible and a reliable scale for mechanically ventilated children, reflected by high intra-class correlation coefficients. As this non-invasive tool is not restricted to a type of ventilator, it could easily be clinical implemented in the ventilated pediatric population. However; correlation studies between the EMG signal measured by surface EMG and esophageal catheters have to be performed.

Automatic detection of oesophageal intubation based on ventilation pressure waveforms shows high sensitivity and specificity in patients with pulmonary disease

BackgroundUnrecognised endotracheal tube misplacement in emergency intubations has a reported incidence of up to 17%. Current detection methods have many limitations restricting their reliability and availability in these circumstances.There is therefore a clinical need for a device that is small enough to be practical in emergency situations and that can detect oesophageal intubation within seconds. In a first reported evaluation, we demonstrated an algorithm based on pressure waveform analysis, able to determine tube location with high reliability in healthy patients.The aim of this study was to validate the specificity of the algorithm in patients with abnormal pulmonary compliance, and to demonstrate the reliability of a newly developed small device that incorporates the technology. Materials and methodsIntubated patients with mild to moderate lung injury, admitted to intensive care were included in the study. The device was connected to the endotracheal tube, and three test ventilations were performed in each patient. All diagnostic data were recorded on PC for subsequent specificity/sensitivity analysis. Results and discussionA total of 105 ventilations in 35 patients with lung injury were analysed. With the threshold D-value of 0.1, the system showed a 100% sensitivity and specificity to diagnose tube location. ConclusionThe algorithm retained its specificity in patients with decreased pulmonary compliance. We also demonstrated the feasibility to integrate sensors and diagnostic hardware in a small, portable hand-held device for convenient use in emergency situations.

Novel method to confirm tracheal intubation based on airway pressures: validation in patients with lung disease

Emergency endotracheal intubation results in accidental oesophageal intubation in up to 17% of patients often with disastrous consequences. We have previously published a highly specific and sensitive novel method to detect endotracheal intubation based on differences in ventilation pressure waveforms in the oesophagus and in the trachea in patients with healthy lungs [1]. A detection algorithm, based on differences in compliance/elasticity between the lung and the oesophagus, generated a D-value indicating tracheal intubation if D >0.5 and oesophageal intubation if D <0.5. The aim of the current study was to validate the algorithm in patients with lung disease.

A novel method to detect accidental oesophageal intubation based on ventilation pressure waveforms

a b s t r a c t Background: Emergency endotracheal intubation results in accidental oesophageal intubation in up to 17% of patients. This is frequently undetected thereby adding to the morbidity and mortality. No current method to detect accidental oesophageal intubation in an emergency setting is both highly sensitive and specific. We hypothesized that, based on differences between the mechanical properties of the oesoph- agus and the trachea/lung, ventilation pressures could discriminate between tracheal and oesophageal intubation. Such a technique would potentially not suffer some of the limitations of current methods to detect oesophageal intubation in emergency conditions such as noisy environment (making clinical assessment difficult) or low/no flow states (reducing the applicability of capnometry). The aim of our study was thus to develop and assess a technique that may more rapidly and accurately differentiate oesophageal from tracheal intubation based on airway pressure gradients. Materials and methods: Forty adult patients undergoing elective surgery were included. In 20 patients the trachea was intubated with an endotracheal tube; in 20 patients the oesophagus was purposefully intubated using an Easytube ® (Rush, Germany). In all patients, a thin air-filled catheter was inserted through the tube lumen until its tip was 1 cm from the distal end, and connected to a pressure transducer. Pressure was recorded simultaneously from a second catheter at the proximal end of the tube. For the first three manual ventilations in each patient, a parameter (D) based on temporal (dP/dt) and spatial (dP/ds) pressure gradients (and reflecting flow divided by elastance) was calculated and evaluated for its ability to discriminate between oesophageal and tracheal intubation. Results and discussion: For all tracheal ventilations, D-values were >0.5 (range 0.6-47.9), while for all oesophageal ventilations D-values were <0.5 (range 0.0005-0.07). Conclusion: This technique has the potential to provide a diagnosis of failed intubation within seconds with high sensitivity and specificity. © 2011 Elsevier Ireland Ltd. All rights reserved.

An automated and standardized neural index to quantify patient-ventilator interaction

IntroductionThe aim of this study was to validate an automated, objective and standardized algorithm for quantifying and displaying patient-ventilator interaction.MethodsUsing a new method to detect patient-ventilator synchrony, the present study re-analyzed previously acquired and published data from 24 mechanically ventilated adult patients (Colombo et al., Crit Care Med. 2011 Nov;39(11):2452–7). Patient-ventilator interactions were evaluated by comparing ventilator pressure and diaphragm electrical activity (EAdi) waveforms, recorded during pressure support ventilation. The EAdi and ventilator pressure waveforms were analyzed for their timings (manually and automatically determined), and the error between the two waveforms was quantified. A new index of patient-ventilator interaction (NeuroSync index), which is standardized and automated, was validated and compared to manual analysis and previously published indices of asynchrony.ResultsThe comparison of manual and automated detection methods produced high test-retest and inter-rater reliability (Intraclass correlation coefficient = 0.95). The NeuroSync index increased the sensitivity of detecting dyssynchronies, compared to previously published indices, which were found to only detect asynchronies.ConclusionThe present study introduces an automated method and the NeuroSync index to determine patient-ventilator interaction with a more sensitive analysis method than those previously described. A dashboard-style of graphical display allows a rapid overview of patient-ventilator interaction and breathing pattern at the bedside.

A novel method to detect accidental oesophageal intubation based on ventilation pressure waveforms

BackgroundEmergency endotracheal intubation results in accidental oesophageal intubation in up to 17% of patients. This is frequently undetected thereby adding to the morbidity and mortality. No current method to detect accidental oesophageal intubation in an emergency setting is both highly sensitive and specific. We hypothesized that, based on differences between the mechanical properties of the oesophagus and the trachea/lung, ventilation pressures could discriminate between tracheal and oesophageal intubation. Such a technique would potentially not suffer some of the limitations of current methods to detect oesophageal intubation in emergency conditions such as noisy environment (making clinical assessment difficult) or low/no flow states (reducing the applicability of capnometry). The aim of our study was thus to develop and assess a technique that may more rapidly and accurately differentiate oesophageal from tracheal intubation based on airway pressure gradients. Materials and methodsForty adult patients undergoing elective surgery were included. In 20 patients the trachea was intubated with an endotracheal tube; in 20 patients the oesophagus was purposefully intubated using an Easytube® (Rüsh, Germany). In all patients, a thin air-filled catheter was inserted through the tube lumen until its tip was 1cm from the distal end, and connected to a pressure transducer. Pressure was recorded simultaneously from a second catheter at the proximal end of the tube. For the first three manual ventilations in each patient, a parameter (D) based on temporal (dP/dt) and spatial (dP/ds) pressure gradients (and reflecting flow divided by elastance) was calculated and evaluated for its ability to discriminate between oesophageal and tracheal intubation. Results and discussionFor all tracheal ventilations, D-values were >0.5 (range 0.6–47.9), while for all oesophageal ventilations D-values were <0.5 (range 0.0005–0.07). ConclusionThis technique has the potential to provide a diagnosis of failed intubation within seconds with high sensitivity and specificity.

A user-independent algorithm for detection of oesophageal intubation based on ventilation pressure waveforms: Validation in a prehospital setting

A user-independent algorithm for detection of oesophageal intubation based on ventilation pressure waveforms: Validation in a prehospital setting

A novel method to detect accidental oesophageal intubation based on ventilation pressure waveforms

a b s t r a c t Background: Emergency endotracheal intubation results in accidental oesophageal intubation in up to 17% of patients. This is frequently undetected thereby adding to the morbidity and mortality. No current method to detect accidental oesophageal intubation in an emergency setting is both highly sensitive and specific. We hypothesized that, based on differences between the mechanical properties of the oesoph- agus and the trachea/lung, ventilation pressures could discriminate between tracheal and oesophageal intubation. Such a technique would potentially not suffer some of the limitations of current methods to detect oesophageal intubation in emergency conditions such as noisy environment (making clinical assessment difficult) or low/no flow states (reducing the applicability of capnometry). The aim of our study was thus to develop and assess a technique that may more rapidly and accurately differentiate oesophageal from tracheal intubation based on airway pressure gradients. Materials and methods: Forty adult patients undergoing elective surgery were included. In 20 patients the trachea was intubated with an endotracheal tube; in 20 patients the oesophagus was purposefully intubated using an Easytube ® (Rush, Germany). In all patients, a thin air-filled catheter was inserted through the tube lumen until its tip was 1 cm from the distal end, and connected to a pressure transducer. Pressure was recorded simultaneously from a second catheter at the proximal end of the tube. For the first three manual ventilations in each patient, a parameter (D) based on temporal (dP/dt) and spatial (dP/ds) pressure gradients (and reflecting flow divided by elastance) was calculated and evaluated for its ability to discriminate between oesophageal and tracheal intubation. Results and discussion: For all tracheal ventilations, D-values were >0.5 (range 0.6-47.9), while for all oesophageal ventilations D-values were <0.5 (range 0.0005-0.07). Conclusion: This technique has the potential to provide a diagnosis of failed intubation within seconds with high sensitivity and specificity. © 2011 Elsevier Ireland Ltd. All rights reserved.

Innovative Life Support in the Acute Respiratory Distress Syndrome

An expanding number of techniques that can provide adequate oxygenation and carbon dioxide elimination in acute respiratory distress syndrome (ARDS) are available for the critical care expert. These include mechanical ventilation with positive end-expiratory pressure (PEEP) 1 and newer modifications of the ventilator's pressure waveforms. 2 In addition, extracorporeal life support (ECLS) using a membrane oxygenator can nearly match the success rate achieved by mechanical ventilation using inverse ratio mechanical ventilation and PEEP in ARDS. These observations were obtained in a randomized controlled clinical trial 3 ; the survival rate was 35% to 40% in ARDS patients who, by previous entry criteria, had only a 10% salvage rate. 4 See also p 383. A new innovation in supportive care, partial liquid ventilation using a perfluorocarbon (PFC) instilled directly into the trachea until airways and alveolar units were partially flooded, appears to be another alternative that can be applied if any one