Christopher T Chenelle

A Comparison of Leak Compensation During Pediatric Noninvasive Ventilation: A Lung Model Study

BACKGROUND: Ventilators used for noninvasive ventilation (NIV) must be able to synchronize in the presence of system leaks. We compared the ability of 7 ICU ventilators and 3 dedicated NIV ventilators to compensate for leaks during pediatric NIV. METHODS: Using a lung simulator, we compared the Maquet Servo-i, Dräger V500, Dräger Carina, Covidien PB840, Respironics V60, Respironics Vision, GE Healthcare/Engström Carestation, CareFusion Avea, Hamilton C3, and Hamilton G5 during increasing (n = 6) and decreasing leaks (n = 6). With a lung simulator we tested 4 leak levels (baseline [BL] 2–3 L/min, L1 5–6 L/min, L2 9–10 L/min, and L3 19–20 L/min); 3 patient weights (10, 20, and 30 kg); and 3 lung mechanics scenarios (normal, obstructive, and restrictive). The ventilator settings were NIV mode, pressure support of 10 cm H2O, and PEEP of 5 cm H2O. The synchronization rate (synchronized cycles/total simulated respirations) was recorded for each ventilator and each leak scenario. Synchronization was defined as triggering without auto-triggering, miss-triggering, delayed cycling, or premature cycling. RESULTS: The mean synchronization rate across all ventilators was 68 ± 27% (range 23–96%) and marked differences existed between the ventilators (P < .001). Significant differences in synchronization rate were observed between the 10-kg model (mean 57 ± 30%, range 17–93%), the 20-kg model (69 ± 30%, 25–98%), and the 30-kg models (77 ± 22%, 28–97%) (P < .001). The synchronization rate for the obstructive model (60 ± 30%, 9–94%) was significantly different from the normal model (71 ± 29%, 18–98%) and the restrictive model (72 ± 28%, 23–98%) (P < .001). The PB840 and the C3 had synchronization rates over 90% overall across all body weights, all lung mechanic profiles, and all leak levels. CONCLUSIONS: Leak compensation in NIV for pediatric use can partially compensate for leaks, but varies widely among ventilators, patient weights, and lung mechanics.

Comparison of commercial and noncommercial endotracheal tube-securing devices.

BACKGROUND: Tracheal intubation is used to establish a secure airway in patients who require mechanical ventilation. Unexpected extubation can have serious complications, including airway trauma and death. Various methods and devices have been developed to maintain endotracheal tube (ETT) security. Associated complications include pressure ulcers due to decreased tissue perfusion. Device consideration includes ease of use, rapid application, and low exerted pressure around the airway. METHODS: Sixteen ETT holders were evaluated under a series of simulated clinical conditions. ETT security was tested by measuring distance displaced after a tug. Nine of the 16 methods could be evaluated for speed of moving the ETT to the opposite side of the mouth. Sensors located on a mannequin measured applied forces when the head was rotated vertically or horizontally. Data were analyzed using multivariate analysis of variance, with P < .05. RESULTS: Median displacement of the ETT by the tug test was 0 cm (interquartile range of 0.0–0.10 cm, P < .001). The mean time to move the ETT from one side of the mouth to the other ranged from 1.25 ± 0.2 s to 34.4 ± 3.4 s (P < .001). Forces applied to the face with a vertical head lift ranged from < 0.2 newtons (N) to a maximum of 3.52 N (P < .001). Forces applied to the face with a horizontal rotation ranged from < 0.2 N to 3.52 N (P < .001). Commercial devices produced greater force than noncommercial devices. CONCLUSIONS: Noncommercial airway holders exert less force on a patients face than commercial devices. Airway stability is affected by the type of securing method. Many commercial holders allow for rapid but secure movement of the artificial airway from one side of the mouth to the other.

Evaluation of an Automated Endotracheal Tube Cuff Controller During Simulated Mechanical Ventilation

BACKGROUND: Maintaining endotracheal tube cuff pressure within a narrow range is an important factor in patient care. The goal of this study was to evaluate the IntelliCuff against the manual technique for maintaining cuff pressure during simulated mechanical ventilation with and without movement. METHODS: The IntelliCuff was compared to the manual technique of a manometer and syringe. Two independent studies were performed during mechanical ventilation: part 1, a 2-h trial incorporating continuous mannikin head movement; and part 2, an 8-h trial using a stationary trachea model. We set cuff pressure to 25 cm H2O, PEEP to 10 cm H2O, and peak inspiratory pressures to 20, 30, and 40 cm H2O. Clinical importance was defined as both statistically significant (P < .05) and clinically significant (pressure change [Δ] > 10%). RESULTS: In part 1, the change in cuff pressure from before to after ventilation was clinically important for the manual technique (P < .001, Δ = −39.6%) but not for the IntelliCuff (P = .02, Δ = 3.5%). In part 2, the change in cuff pressure from before to after ventilation was clinically important for the manual technique (P = .004, Δ = −14.39%) but not for the IntelliCuff (P = .20, Δ = 5.65%). CONCLUSIONS: There was a clinically important drop in manually set cuff pressure during simulated mechanical ventilation in a stationary model and an even larger drop with movement, but this was significantly reduced by the IntelliCuff in both scenarios. Additionally, we observed that cuff pressure varied directly with inspiratory airway pressure for both techniques, leading to elevated average cuff pressures.

Performance of Leak Compensation in All-Age ICU Ventilators During Volume-Targeted Neonatal Ventilation: A Lung Model Study

BACKGROUND: Volume-targeted ventilation is increasingly used in low birthweight infants because of the potential for reducing volutrauma and avoiding hypocapnea. However, it is not known what level of air leak is acceptable during neonatal volume-targeted ventilation when leak compensation is activated concurrently. METHODS: Four ICU ventilators (Servo-i, PB980, V500, and Avea) were compared in available invasive volume-targeted ventilation modes (pressure control continuous spontaneous ventilation [PC-CSV] and pressure control continuous mandatory ventilation [PC-CMV]). The Servo-i and PB980 were tested with (+) and without (−) their proximal flow sensor. The V500 and Avea were tested with their proximal flow sensor as indicated by their manufacturers. An ASL 5000 lung model was used to simulate 4 neonatal scenarios (body weight 0.5, 1, 2, and 4 kg). The ASL 5000 was ventilated via an endotracheal tube with 3 different leaks. Two minutes of data were collected after each change in leak level, and the asynchrony index was calculated. Tidal volume (VT) before and after the change in leak was assessed. RESULTS: The differences in delivered VT between before and after the change in leak were within ±5% in all scenarios with the PB980 (−/+) and V500. With the Servo-i (−/+), baseline VT was ≥10% greater than set VT during PC-CSV, and delivered VT markedly changed with leak. The Avea demonstrated persistent high VT in all leak scenarios. Across all ventilators, the median asynchrony index was 1% (interquartile range 0–27%) in PC-CSV and 1.8% (0–45%) in PC-CMV. The median asynchrony index was significantly higher in the Servo-i (−/+) than in the PB980 (−/+) and V500 in 1 and 2 kg scenarios during PC-CSV and PC-CMV. CONCLUSIONS: The PB980 and V500 were the only ventilators to acclimate to all leak scenarios and achieve targeted VT. Further clinical investigation is needed to validate the use of leak compensation during neonatal volume-targeted ventilation.

Endotracheal Tubes Cleaned With a Novel Mechanism for Secretion Removal: A Randomized Controlled Clinical Study

INTRODUCTION: Intubation compromises mucus clearance, allowing secretions to accumulate inside the endotracheal tube (ETT). The purpose of this trial was to evaluate a novel device for ETT cleaning. We hypothesized that its routine use would reduce tube occlusion due to mucus accumulation, while decreasing airway bacterial colonization. METHODS: Subjects were randomized to either the use of the device every 8 h, or the institutional standard of care (blind tracheal suction) only. ETTs were collected at extubation and analyzed with high-resolution computed tomography (HRCT) for quantification of mucus volume. Microbiological testing was performed on biofilm samples. Vital signs and ventilatory settings were collected at the bedside. In-hospital follow-up was conducted, and a final evaluation survey was completed by respiratory therapists. RESULTS: Seventy-four subjects expected to remain intubated for longer than 48 h were enrolled (77 ETTs, 37 treatment vs 40 controls). Treated tubes showed reduced mucus accumulation (0.56 ± 0.12 vs 0.71 ± 0.28 mL; P = .004) and reduced occlusion (6.3 ± 1.7 vs 8.9 ± 7.6%; P = .039). The HRCT slice showing the narrowest lumen within each ETT exhibited less occlusion in cleaned tubes (10.6 ± 8.0 vs 17.7 ± 13.4%, 95% CI: 2–12.1; P = .007). Data on microbial colonization showed a trend in the treatment group toward a reduced ETT-based biomass of bacteria known to cause ventilator-associated pneumonia. No adverse events were reported. The staff was satisfied by the overall safety and feasibility of the device. CONCLUSION: The endOclear is a safe and effective device. It prevents luminal occlusion, thereby better preserving ETT nominal function.

Effects of Leak Compensation on Patient-Ventilator Synchrony During Premature/Neonatal Invasive and Noninvasive Ventilation: A Lung Model Study

BACKGROUND: During both nasal noninvasive ventilation (NIV) and invasive ventilation of neonates, the presence of air leaks causes triggering and cycling asynchrony. METHODS: Five ICU ventilators (PB840, PB980, Servo-i, V500, and Avea) were compared in available invasive ventilation and NIV ventilator modes (pressure control continuous spontaneous ventilation [PC-CSV] and pressure control continuous mandatory ventilation [PC-CMV]). The V500 and Avea do not provide PC-CSV and PC-CMV in NIV. The Servo-i and Avea were tested with and without their proximal flow sensor. The ASL 5000 lung model (version 3.5) was used to simulate 4 neonatal scenarios (body weight 0.5, 1, 2, and 4 kg). The ASL 5000 was ventilated via endotracheal tube (invasive ventilation) or nasal cannula (NIV) with 4 different leaks. RESULTS: The Avea (without flow sensor) during invasive ventilation and Servo-i and PB840 during NIV were not triggered by inspiratory efforts of the ASL 5000 at the baseline leak in the 0.5 kg scenario. In invasive ventilation, overall (median) asynchrony index was significantly lower with the PB980 (1%) and V500 (3%) than with the Servo-i (with flow sensor, 50%; without flow sensor, 50%) and Avea (with sensor, 50%; without sensor, 62%) (P < .05 for all comparisons). The PB840 (33%) was significantly different from all ventilators (P < .05). In NIV, the asynchrony index was significantly lower in PB980 (2%) than in the Servo-i (with sensor, 100%; without sensor, 100%) and PB840 (75%) (P < .05 for both). There was no difference in asynchrony index between PC-CSV and PC-CMV in all tested conditions and ventilators. CONCLUSIONS: The ability of leak compensation to prevent asynchronous breathing varied widely between ventilators and lung mechanics. The PB980 and V500 were the only two ventilators to acclimate to all leak scenarios in invasive ventilation, and PB980 was the only ventilator to acclimate to all leak scenarios in NIV.

Performance of the PneuX System: A Bench Study Comparison With 4 Other Endotracheal Tube Cuffs

BACKGROUND: Cuff design affects microaspiration, a risk factor for pneumonia. We questioned whether the PneuX low-volume fold-free cuff design would prevent cuff leakage and maintain the same tracheal wall pressure as high-volume, low-pressure (HVLP) cuffs. METHODS: We evaluated 4 HVLP-cuffed endotracheal tubes (ETTs), Hi-Lo (polyvinyl chloride [PVC]), Microcuff (polyurethane [PU]), SealGuard (PU + tapered), and TaperGuard (PVC + tapered), and the PneuX with its dedicated tracheal seal monitor. In Part 1, we determined tracheal wall pressure using each cuffs capacity to support water columns across recommended intracuff pressures. In Part 2, we evaluated the tracheal seal monitor function at recommended settings. In Part 3, we compared leakage volumes of all ETTs during 30 min of simulated mechanical ventilation or during 8 h if no leak occurred. Parts 1 and 3 were performed with/without lubrication and PEEP. RESULTS: In Part 1, PneuX cuffs exerted an average tracheal wall pressure of 27.4 ± 2.4 cm H2O at the recommended intracuff pressure of approximately 80 cm H2O. Tracheal wall pressure did not differ among HVLP cuffs (19.6 ± 1.4 to 29.5 ± 1.4 cm H2O). In Part 2, preinflation intracuff pressure affected the time to obtain tracheal seal monitor pressure attainment (P < .01). The tracheal seal monitor generated average calculated tracheal wall pressure of 33.4 ± 1.2 cm H2O. In Part 3, PneuX ETT showed no leak across 8 h for all trials. Overall, leakage volume was lower with PU (P < .01) and PneuX (P < .01) than with PVC cuffs, regardless of shape, and lower with lubrication and/or PEEP (all P < .01). In each HVLP cuff, lubrication alone eliminated leak at an intracuff pressure of ≤30 cm H2O. CONCLUSIONS: The PneuX cuff generally exerted acceptable tracheal wall pressure, but the tracheal wall pressure monitor allowed pressures exceeding 30 cm H2O in some trials and was the only ETT to prevent leak in all tests. For HVLP cuffs, leak was reduced by PU and PEEP and eliminated by lubrication.

Ventilation Efficacy of Video-Laryngoscopes Equipped With a Ventilation Feature

INTRODUCTION: Achieving effective ventilation is challenging for anesthesia care providers and emergency medical personnel, as difficult mask ventilation and difficult intubation frequently occur. The aim of this study was to determine whether video-laryngoscopes equipped with a ventilation feature can produce effective ventilation. METHODS: An intubation mannequin with its trachea connected to a model lung with compliance 50 (normal compliance: C50) and 20 mL/cm H2O (low compliance: C20) was used. Ventilation was established via a ventilation catheter (inner diameter 3.5 mm, 50 cm length) extending to the tip of the video-laryngoscope blade. Three different views of the vocal cords (grade 1, vocal cords fully visualized; grade 2, partial vocal cord visualization; grade 3, only epiglottis visualized) were tested. Ventilation was provided by jet ventilator (Jet). The Jet was operated at 10, 15, and 20 psi (Jet10, Jet15, and Jet20). Effective tidal volume (VT) was defined as a VT greater than anatomical dead space (150 mL). RESULTS: In C50, Jet15 and Jet20 generated effective VT in all vocal cord views (for Jet15: grade 1, 663 ± 33 mL; grade 2, 363 ± 25 mL; and grade 3, 198 ± 9 mL; for Jet20: grade 1, 1,005 ± 114 mL; grade 2, 484 ± 38 mL; grade 3, 268 ± 8 mL, respectively). In C20, Jet15 and Jet20 generated effective VT in grades 1 and 2 (Jet15: grade 1, 288 ± 8 mL; grade 2, 160 ± 20 mL; grade 3, 81 ± 7 mL; Jet20: grade 1, 421 ± 20 mL; grade 2, 222 ± 16 mL; grade 3, 111 ± 8 mL, respectively). Jet10 achieved effective VT in grade 1 and 2 (grade 1, 354 ± 6 mL; grade 2, 223 ± 37 mL, respectively) in C50 and grade 1 (163 ± 12 mL) in C20. CONCLUSIONS: Video-laryngoscopes equipped with a ventilation feature provided effective VT in simulated clinical scenarios. Further clinical study is required to validate these findings.