Airway Pressure Monitoring Research Articles

Anesthetic management of a case of pulmonary alveolar proteinosis for whole lung lavage

Abstract Pulmonary Alveolar Proteinosis (PAP) is a rare disease of the lungs characterized by deposition of lipo-proteinaceous material in the alveoli. This leads to reduced lung compliance and V/Q mismatch, causing respiratory failure. Patients with PAP may be posted for Whole Lung Lavage (WLL) under anesthesia, which is a challenging case for anesthetists. Preexisting respiratory failure is complicated by requirement of single lung ventilation with the help of double lumen tube during the procedure. Intraoperative ventilation is difficult and is managed with blood gas and airway pressure monitoring. Some degree of hypoxemia and hypercapnia may have to be tolerated. Large volumes of fluid are instilled into the lung which may cause hypothermia, hypervolemia, and electrolyte disturbances. These patients frequently require elective ventilation and intensive care admission in the postoperative period. We report the case of a young woman with PAP, posted for unilateral WLL under anesthesia. We wish to highlight the possible challenges posed by this case and how to conduct a safe anesthesia for this patient.

Take an OSA pill and call me in the morning.

Take an OSA pill and call me in the morning.

Highly Sensitive Air Pressure Sensor Based on Fabry-Perot Interference

A highly sensitive optical fiber air pressure sensor based on Fabry–Perot interferometer is proposed and demonstrated. The sensor is fabricated by flat-cut single-mode optical fiber, capillary glass tube, stainless steel sleeve, nylon substrate, and metal aluminum film. The finite element simulation was performed in two steps using the COMSOL Multiphysics software. In the first step, the structural mechanics module is used to simulate the deformation of the membrane under a fixed pressure, so as to obtain the corresponding sensor cavity lengths under different pressure. In the second step, the wave optics module is used to get the reflection spectrum of the sensor under different cavity lengths. Then the linear relationship between the reflection spectral shift of the sensor and the pressure is obtained. Thus, the average spectral sensitivity of the sensor under air pressure is −3.10335 nm/KPa. A metal-aluminum thin film F-P cavity sensor was fabricated for experimental verification. According to the experimental results, when the air pressure ranges from 0 Pa to 1000 Pa, the spectral sensitivity of the sensor is as high as −3.10 nm/KPa. This is almost consistent with the simulation result. The sensor has exhibited potential application in the fields of measurement of airway pressure and environmental monitoring.

Bag valve resuscitator versus Mapleson C circuit during manual ventilation: A bench top study

BackgroundManual ventilation is life saving in critically ill patients. The lack of airway pressure monitoring makes it operator and device dependent. In this bench top-study, we compared a self- inflating bag valve resuscitator and a Mapleson C circuit during manual ventilation performed by critical care nurses under normal and pathologic conditions, with a special focus on delivered positive end expiratory pressure (PEEP). MethodsThree different respiratory patterns (normal, restrictive and obstructive) were reproduced by a breathing simulator. Twenty nurses provided manual ventilation with a specific ventilatory pattern. Airway pressure, tidal volume and respiratory rate were recorded. Absolute value, error (difference between recorded and target values) and variability of PEEP were analysed. Results3820 breathing traces were analysed. PEEP error was significantly higher with Mapelson C (43.3% vs 5.9% respectively, p < 0.001). This finding was confirmed regardless of operator skill and scenario. PEEP was more variable with Mapelson C (p < 0.05 in all scenarios). Ventilation of obstructive patients with Mapelson C resulted in higher PEEP levels compared to the reference value. Conversely, in the restrictive setting, PEEP was lower. Difference between PEEP and the minimum pressure recorded during the respiratory cycle was significantly higher with Mapelson C (p < 0.05). ConclusionsManual ventilation with a Mapleson C circuit delivered a less accurate and less stable PEEP level compared to a self-inflating bag valve resuscitator.

Going around in circles. Is there a continuing need to use the T-piece circuit in the practice of pediatric anesthesia?

Anesthetic equipment, including breathing circuits, has evolved over time. The T-piece circuit, in its various forms, was designed to meet the needs of its time. As equipment and techniques have moved on, it is timely to consider the place of the T-piece in modern pediatric anesthetic practice. Today the circle system is a ubiquitous part of anesthesia. When integrated with a modern anesthetic machine it offers precise control of ventilation together with continuous monitoring of airway pressure and flow: but at the cost of complexity. In comparison the T-piece offers a simple cheap lightweight design, so ergonomic in use that it almost becomes part of the anesthetist: but lacks the control and the barriers to unsafe use of more sophisticated systems. In addition, it requires high fresh gas flow adding to cost and environmental pollution. This pro-con debate discusses whether there remains a case for continuing to use the T-piece circuit in preference over other options. Possible indications for the T-Piece are discussed together with alternative strategies. The limitations of the circle system, the T-piece, and other alternative (such as self-inflating resuscitator bag) are discussed with respect to pediatric anesthetic practice.

An alternative model in the provision of CPAP in sleep apnea: a comparative cost analysis

BackgroundTo conduct a pilot study on an alternative model for the provision of respiratory therapies in sleep apnea-hypopnea syndrome (SAHS) by internalizing the service with the purchase, monitoring and control of continuous positive airway pressure (CPAP) equipment by the hospital.MethodsAn observational, prospective pilot study of comparative cost analysis by internalizing the service to include all patients up to a budget limit of 5000 euros. The cost of internalizing the service included the acquisition of CPAP equipment and all the necessary accessories in addition to the nursing days necessary to track the patients. Patient satisfaction was assessed by a survey of the hospital service.ResultsTwenty-one patients with 23,046 patient-days of follow-up were included. The cost of the internalized system was 6825.11 €. The cost of the outsourced system over the same period would have been 22,781.18 €; thus, the direct saving was 15,956.07 €. The cost per device per day of the internalized system was 0.30 € versus the 0.99 € that the outsourced system would have cost during the study period. In the satisfaction survey, 12 (70.6%) patients indicated that they preferred the service of the hospital over that of the external company. No patient preferred the outsourced system.ConclusionsThe internalization of CPAP service represents significant cost savings from a hospital perspective and an improvement in patients’ perceptions of the quality of service.

The Perioperative and Anesthetic Adverse Events in Thailand (PAAd Thai) Study of Endobronchial Intubation: An Analysis of 2,000 Incident Reports

Background: The Royal College of Anesthesiologists of Thailand hosted a multicentered project, namely the Perioperative and Anesthetic Adverse Events in Thailand (PAAd Thai) Study. Objective: The aims of the present study were to investigate incidences, contributing factors and suggested preventive strategies of anesthesia-related complications particularly the endobronchial intubation (EBI). Materials and Methods: The PAAd Thai study was a collaborative incident report among 22 hospitals across Thailand. After approval by the Institutional Ethical Committee, the structured incident report together with open ended data record form of anesthesia-related complications such as cardiac arrest, death within 24 hours, and respiratory complications including EBI were requested to be sent to the data management center together with monthly statistics of anesthesia service in each hospital for 12 months (between January 2015 and December 2015) on an anonymous and voluntary basis. The EBI reports were reviewed by three anesthesiologists. Any discretion was discussed to achieve a consensus. Descriptive statistics were used. Results: Among the first 2,000 incident reports, there were 23 EBIs, at the rate of 1.06:10,000 (95% CI 0.62 to 1.49) or 1.15% of all reports. Two-thirds of the incidents occurred in patients with age less than 5 years old and more than 60 years old, and in elective cases. The common sites of surgery were trunk, head and neck, and laparoscopic procedures. EBIs were diagnosed by pulse oximeter (13 cases, 54.0%), increased airway pressure (four cases, 17.2%) and clinical monitoring (four cases 17.2%). Common phases of detection were pre-induction (one case, 4.3%), induction (nine cases, 39.2%), maintenance (12 cases, 52.2%), and emergence (one case, 4.3%). Contributing factors were lack of knowledge, inexperience, and haste, while factors minimizing the incidents were having experience and vigilance. Suggested preventive strategies were additional training, including simulation, practice guidelines, improvement of supervision, and communication. Conclusion: The authors have found that EBI was uncommon, but it is one of the serious anesthesia-related adverse events. It can happen anytime during the entire course of anesthesia. Under these circumstances, careful monitoring and vigilance of the anesthesiologists is essential. Keywords: Anesthesia, Complication, Endobronchial intubation, Intubation, Hypoxia

SUN-595 Comparative Comorbidity Burden Among Patients with Prader-Willi Syndrome: A Population-Level Cohort Study

Prader-Willi syndrome (PWS) is a rare, complex multi-system genetic disorder characterized by hyperphagia and abnormal food-related behaviors that contribute to severe morbidity and early mortality and to a significant burden on patients and caregivers. The hyperphagia seen in people with PWS can result in significant obesity. This study assessed rates of comorbidities associated with obesity, including type II diabetes (T2D), cardiovascular disease (CVD), and sleep apnea (SA) in a large US PWS vs. a non-PWS cohort. Methods: T2D, CVD, and SA conditions for privately insured PWS and non-PWS patients aged <65 years were identified via ICD diagnosis codes in deidentified medical claims provided by IQVIA™ Health Plan Claims Data (1/2006 - 11/2018). Patients were grouped into age-bands of 0–2, 3–8, 9–17, 18–26, 27–34, 35–49, and 50–64 years. Patients were required to have ≥12 months of enrollment, and observations were segmented into 12-month patient years. Due to patient privacy, figures that represent fewer than 11 patients are not shared and are represented as a non-zero figure (NZF). Results: 5,060 PWS and 31,093 non-PWS patient years representing 1,461 and 9,656 unique patients were eligible for analysis. T2D was detected in 8% of PWS patients age 9–17 (vs a NZF in non-PWS), 19% (vs 1%) in ages 18–26, and 27% in ages 27–34, 35–49, and 50–64 (vs 2, 5, and 13%, respectively). Comorbid CVD was detected in 25% of PWS patients age 0–2 (vs 1% in non-PWS), 11% (vs 1%) in ages 3–8, 15% (vs 1%) in ages 9–17, 29% (vs 4%) in ages 18–26, 44% (vs 11%) in ages 27–34, 60% (vs 27%) in ages 35–49, and 78% (vs 53%) in ages 50–64. Sleep apnea was detected in a NZF of non-PWS patients aged 0–2 and in all age groups 3–8, 9–17, and 18–26, compared to 37%, 22%, 17%, and 18% of PWS patients, respectively. Sleep apnea prevalence in PWS patients was 18% (vs 1% in non-PWS) in ages 27–34, 15% (vs 3%) in ages 35–49, and 16% (vs 4%) in ages 50–64.The largest disparities between PWS and non-PWS T2D prevalence was observed in the 9–17 and 18–26 age groups. Manifestations of CVD in PWS patients ages 0–2 was characterized by high rates of congenital atrial septal and patient ductus arteriosus defects, and in adolescent and adult PWS patients featured markedly higher rates of hypertension and hyperlipidemia than non-PWS cohorts. The proportion of PWS patients with SA that also received continuous positive airway pressure or oxygen monitoring ranged from 38% to 71%. Conclusions: Across all age groups, compared to non-PWS subjects, individuals with PWS experience markedly higher rates of CVD, T2D, and SA. The increased rate of CVD in the earliest age groups is consistent with previously observed increases in congenital heart defects with PWS. The frequency and early age of onset of hypertension, hyperlipidemia, T2D and SA emphasize the need for even more aggressive management of underlying drivers such as hyperphagia and the resulting obesity and metabolic dysfunction.

The value of the pharyngeal airway pressure monitoring test in topodiagnosis of OSA

Objective:To analyses the value of an improved methods of Muller's test, pharyngeal airway pressure monitoring test（PAPMT）, in topodiagnosis of OSA. Method:One hundred and one cases with OSA（AHI≥5 times per hour） and 30 normal adults were included in the study. Under the pressure monitoring, the electronic laryngoscope were stayed at the palatopharyngeal and glossopharyngeum. First, observe the maximum expiratory pressure and the minimum spiratory pressure. And then measure and record changes of pharynx cross-sectional area at palatopharyngeal and glossopharyngeum under the different pressure. At Last, analyses the correlation between changes of Pharynx cross-sectional area with polysomnography（PSG）. Result:①In 101 cases with OSA, the maximal inspiratory pressure of Müller's manerver distribution is between 1 and 8 kPa. ②The changes of pharynx cross-sectional area of OSA at palatopharyngeal and glossopharyngeum is significantly greater than the control group, and there were obvious differences between OSA and the control group. ③In OSA group, the plug rate at palatopharyngea was 96% and the plug rate at glossopharyngeum is 34% at the minimum pressure. There are no cases have pharynx jams at the control group. ④The main cause of the palatopharyngeal obstruction was strictures in left and right（73%）, and the anatomical factors causing obstruction mainly were, thicken of the pharyngeal wall. The main cause of the hypopharyngeal obstruction was strictures in front and back（71%）, and the redundant lymph tissue at tongue base and posterior displacement of the tongue base, and collapse of pharyngeal wall played an important role at tongue-pharyngeal obstruction. ⑤The changes of pharynx cross-sectional area at palatopharyngeal and glossopharyngeum when the pressure is ±4 kPa is greater than when the pressure is ±2 kPa. ⑥When the pressure is ±2 kPa, The changes of pharynx cross-sectional area at palatopharyngeal is greater than at glossopharyngeum. ⑦Diminished pharyngeal apertures and collapsibility were associated with increased rates of apnea and hypopnea index and the suction pressure（P<0.05）. Conclusion:①PAPMT is able to measure and calculate the changes of pharynx cross-sectional area, determine the site of obstruction, and help the treatment. ②The primary site of obstruction is at velopharyngeal in OSA group. ③The changes of pharynx cross-sectional area at palatopharyngeal and glossopharyngeum of patients can reflects the severity of the OSA.

Reply to Chalkias and Xanthos: Airway Pressure Monitoring May Improve Small Airway Flow, Hemodynamics, and Tissue Oxygenation

Reply to Chalkias and Xanthos: Airway Pressure Monitoring May Improve Small Airway Flow, Hemodynamics, and Tissue Oxygenation

Interpretation of the transpulmonary pressure in the critically ill patient.

Mechanical ventilation is a life-saving procedure, which takes over the function of the respiratory muscles while buying time for healing to take place. However, it can also promote or worsen lung injury, so that careful monitoring of respiratory mechanics is suggested to titrate the level of support and avoid injurious pressures and volumes to develop. Standard monitoring includes flow, volume and airway pressure (Paw). However, Paw represents the pressure acting on the respiratory system as a whole, and does not allow to differentiate the part of pressure that is spent di distend the chest wall. Moreover, if spontaneous breathing efforts are allowed, the Paw is the sum of that applied by the ventilator and that generated by the patient. As a consequence, monitoring of Paw has significant shortcomings. Assessment of esophageal pressure (Pes), as a surrogate for pleural pressure (Ppl), may allow the clinicians to discriminate between the elastic behaviour of the lung and the chest wall, and to calculate the degree of spontaneous respiratory effort. In the present review, the characteristics and limitations of airway and transpulmonary pressure monitoring will be presented; we will highlight the different assumptions underlying the various methods for measuring transpulmonary pressure (i.e., the elastance-derived and the release-derived method, and the direct measurement), as well as the potential application of transpulmonary pressure assessment during both controlled and spontaneous/assisted mechanical ventilation in critically ill patients.

Microbiological monitoring of continuous positive airway pressure and resuscitation equipment in very-low birth weight infants.

BackgroundTo investigate the colonization of respiratory equipment and the rate of respiratory infections of very-low birth weight (VLBW) infants.MethodsThe prospective study includes 26 VLBW infants on continuous airway pressure (CPAP) from September until December 2012. Swabs from respiratory equipment and colonization/infections were evaluated.ResultsA total of 603 swabs was cultured with 298 isolates; 59% of cultures from CPAP equipment (n=337; 95% confidence interval (CI; 54;64)) and 19% from ambu bags (n=51; 95% CI (14;24)) were positive. Overall, 181/201 CPAP prongs and masks hosted 221 microorganisms. Colonization on days 3 and 7 were 93% and 87%, respectively, with an increase in pathogens and a decrease in skin flora (79% vs. 68%). Comparing the 58 paired swab results from days 3 and 7 showed an increase in Gram-negative bacteria (P=0.014). Eighteen infants had positive weekly screening results, with similar colonization of CPAP equipment, dominated by Enterobacteriacae. Pneumonia was diagnosed in two infants.ConclusionOf the CPAP equipment close to the patient, 90% was colonized with microorganisms increasing during 1 week of CPAP. The pathogens were dominated by gastrointestinal bacteria, and persisted over weeks. Frequent cleaning did not prevent pneumonia, although pneumonia rates were rare.

Telemedicine Applications in Sleep Disordered Breathing

Telemedicine as a means of remote patient-physician interaction is growing and virtual consultations with sleep specialists are feasible. Potential benefits of telemedicine include improved access to health care, reduced waiting time for appointments, and increased adherence to treatment plans. Telematic communications and new information technologies could also be useful to establish diagnostic and therapeutic strategies. It is important to install cost-efficient technologies for an initial simple diagnosis, rapid treatment initiation and for long-term monitoring of treatment adherence and compliance. Diagnostic telemedicine applications include telemonitored polysomnography, long-term polygraphic monitoring, and remote continuous positive airway pressure titration and monitoring.

Abstract PR574

Background & Objectives: Percutaneous trans-tracheal and subglottic cannulation jet ventilation techniques are well established in current practice(1,2,3). However, when oxygenation via either route is not possible eg abnormal tracheal anatomy, hand-held high frequency jet ventilation (HFJV) using a Venturi needle trans-stomally is a recognised, safe technique in short, non-laser supra-glottic procedures(4). Percutaneous tracheostomy techniques have been studied(4). However, there are no studies clarifying the optimum angle for hand-held jet ventilation needle position to obtain appropriate tidal volumes. Aim:We evaluated the optimal maximal tidal volume obtained at three pre-determined angles of manual trans-stomal HFJV. Materials & Methods: A benchtop manikin study was performed to assess the maximal tidal volume obtained using a Venturi Jet ventilation needle manually held at 3 pre-determined angles; 45, 60 and 75 degrees measured using a digital protractor from the trans-stomal site. An 8mm standard Portex tracheostomy stoma was created. HFJV was delivered (constant pressure = 2 bar; frequency = 100min-1) via the needle attached to an automated Jet ventilator equipped with airway pressure monitoring and automatic gas cut-off. The needle was manually held at a constant distance of 2cm and tidal volume measured with spirometry attached to a 2 litre manual ventilation bag. Results: A one-way ANOVA was calculated for the observed tidal volumes at each angle, detecting a statistically significant difference between groups [F(2.15) 8.21 p=0.0390]. Correlation coefficients(R) were calculated between groups showing a positive association between all angles: the greatest between 75 vs 60 degrees R=0.75, with 65 vs 45 degrees R= 0.63 following, and finally and 75 vs 45 degrees R=0.47. Median and interquartile ranges were plotted (Fig.1) showing an increase in tidal volumes with increase in angle.Conclusion: This study demonstrated a statistically significant difference in observed tidal volumes when only changing the angle of Venturi needle HFJV application. A positive correlation between all angles showed larger tidal volumes were obtained at steeper angles with volumes increasing over time at a constant angle. This has clinical relevance in post-laryngectomy patients undergoing short, supra-glottic procedures in maintaining adequate oxygenation for their duration. Limitations include a small data set. Future work should focus on evaluation in the clinical setting using a variety of angles, jet ventilation needles and patient groups.

The obese patient undergoing nonbariatric surgery.

This article provides the reader with recent findings on the pathophysiology of comorbidities in the obese, as well as evidence-based treatment options to deal with perioperative respiratory challenges. Our understanding of obesity-associated asthma, obstructive sleep apnea, and obesity hypoventilation syndrome is still expanding. Routine screening for obstructive sleep apnea using the STOP-Bang score might identify high-risk patients that benefit from perioperative continuous positive airway pressure and close postoperative monitoring. Measures to most effectively support respiratory function during induction of and emergence from anesthesia include optimal patient positioning and use of noninvasive positive pressure ventilation. Appropriate mechanical ventilation settings are under investigation, so that only the use of protective low tidal volumes could be currently recommended. A multimodal approach consisting of adjuvants, as well as regional anesthesia/analgesia techniques reduces the need for systemic opioids and related respiratory complications. Anesthesia of obese patients for nonbariatric surgical procedures requires knowledge of typical comorbidities and their respective treatment options. Apart from cardiovascular diseases associated with the metabolic syndrome, awareness of any pulmonary dysfunction is of paramount. A multimodal analgesia approach may be useful to reduce postoperative pulmonary complications.

Transpulmonary pressure monitoring during mechanical ventilation: a bench-to-bedside review.

Different ventilation strategies have been suggested in the past in patients with acute respiratory distress syndrome (ARDS). Airway pressure monitoring alone is inadequate to assure optimal ventilatory support in ARDS patients. The assessment of transpulmonary pressure (PTP) can help clinicians to tailor mechanical ventilation to the individual patient needs. Transpulmonary pressure monitoring, defined as airway pressure (Paw) minus intrathoracic pressure (ITP), provides essential information about chest wall mechanics and its effects on the respiratory system and lung mechanics. The positioning of an esophageal catheter is required to measure the esophageal pressure (Peso), which is clinically used as a surrogate for ITP or pleural pressure (Ppl), and calculates the transpulmonary pressure. The benefits of such a ventilation approach are avoiding excessive lung stress and individualizing the positive end-expiratory pressure (PEEP) setting. The aim is to prevent over-distention of alveoli and the cyclic recruitment/derecruitment or shear stress of lung parenchyma, mechanisms associated with ventilator-induced lung injury (VILI). Knowledge of the real lung distending pressure, i.e. the transpulmonary pressure, has shown to be useful in both controlled and assisted mechanical ventilation. In the latter ventilator modes, Peso measurement allows one to assess a patient's respiratory effort, patient-ventilator asynchrony, intrinsic PEEP and the calculation of work of breathing. Conditions that have an impact on Peso, such as abdominal hypertension, will also be discussed briefly.

Evaluation of Monitoring of Continuous Positive Airway Pressure (CPAP) Therapy Compliance in Primary Care Setting: A Quality Initiative Project

Evaluation of Monitoring of Continuous Positive Airway Pressure (CPAP) Therapy Compliance in Primary Care Setting: A Quality Initiative Project

Performance assessment of a medical device for home monitoring of CPAP treatment in patients with obstructive sleep apnoea syndrome

Introduction Home monitoring of Continuous Positive Airway Pressure (CPAP) treatment is key to ensure on the long term patient compliance and normalisation of the apnoea-hypopnoea index (AHI). Those parameters are currently collected from CPAP devices in a heterogeneous manner as different parameters are measured and proprietary detection algorithms score differently respiratory events. The AL539 device was developed to allow remote control of treatment duration and of several efficacy parameters including residual AHI, in adults with obstructive sleep apnoea syndrome (OSA), whatever the CPAP they use. To assess the performance of the AL539 device, by comparing its measurements (CPAP treatment duration and residual AHI) to those obtained by respiratory polygraphy (Embletta GOLD®), used as reference. Materials and methods Monocentric, prospective, single-group clinical trial. Adult patients with OSA equipped with a CPAP for at least 2 months and requiring an in-lab control respiratory polygraphy were included (82% males, mean age 61 yrs, BMI ranging 23–41 kg/m 2 ). Recordings were performed while using their usual CPAP and interface. Descriptive analyses on 14 patients are presented. Results Recordings were performed with 6 different CPAPs and 3 different interfaces (nasal mask, face mask and nasal pillow). Minimum duration of the recording night was 6.75 h. Mean duration of CPAP treatment measured by the AL539 and the polygraph were similar, with an absolute difference of 2.4 min overall on the recording night (95% confidence interval −0.2 to 5.1). AHI derived from polygraphic data was 6.4 3.4/h, and mean absolute difference of the corresponding AHI estimated by AL539 was 2.5/h (95% confidence interval 1.4–3.6). Conclusion AL539 allows a precise measurement of CPAP treatment duration. As expected by the difference in the methods used to score respiratory events, AL539. Acknowledgement Acknowledgements to sleep technologists of sleep center of Hotel-Dieu.

Anesthetic Management of Patients With Anterior Mediastinal Masses Undergoing Chamberlain Procedure (Anterior Mediastinostomy)

Anesthetic Management of Patients With Anterior Mediastinal Masses Undergoing Chamberlain Procedure (Anterior Mediastinostomy)

Brain death after Concorde positioning for supracerebellar-infratentorial approach: Unanswered questions and lessons learned

Brain death after Concorde positioning for supracerebellar-infratentorial approach: Unanswered questions and lessons learned