Inspiratory Peak Research Articles

Design and Build a Ventalitor Tester With PIP and PIF Waveform Displays As Validation (PIP)

PIP (Peak Inspiratory Pressure) is the highest level of pressure exerted into the lungs by the ventilator during inhalation. This PIP parameter is important for monitoring because inappropriate PIP values ​​can lead to fatal errors in patients. PIP should be kept below 20 to 25 cm H2O each time ventilation. This PIP control can be a value as well as a waveform. This waveform display is also used to validate the ventilator output. Checking the output on this ventilator is used using a ventilator tester. The purpose of this research is to get the accuracy and precision of the sensor to display the waveform and PIP value of the ventilator output. The procedure of this research is to use MPX5010GP to detect the pressure value on the ventilator and then display the value and waveform of the PIP. From this study, the results of the measurement of accuracy and precision from the MPX5010 sensor to detect PIP and display a waveform graph are said to be good. This is because the highest error value is ±6.27% at the 15 CmH20 setting. While the value of the largest standard deviation at the 15 CmH20 setting is 0.837 and the greatest uncertainty value at the 15 CmH20 setting is 0.033. Then, the largest correction value is found in the 25 CmH20 setting, which is 1.56. PIF monitoring is carried out to maximize service to patients and maximize ventilator care.

High Flow Oxygen Therapy – Risks and Rewards

Introduction High Flow Oxygen Therapy via Nasal Cannula (HFNC) has documented advantages over conventional oxygen therapy (COT). It’s been noted to improve the survival rate among patients with acute hypoxemic respiratory failure, and potentially reduce the incidence of more invasive care. Adjustable oxygen concentration and higher flows that match the inspiratory demand of the patient with respiratory distress result in less entrainment of room air, which dilutes the fraction of inspired oxygen (FiO2) and therefore reduces effectiveness of intended use. Higher flows have been demanded by the clinical community and are associated with a reduction of both PaCO2 and metabolic work. Newer High Flow devices offer higher flow rates up to 80 liters per minute. We examined whether the use of 60 and 80 liters per minute set flows would create an increased risk of gastric insufflation and possibly aspiration. Methods Bench study to compare the pressures generated using different flow rates in two commercially available HFNC devices in three different conditions: Open and closed system (mouth) breathing, breathing against active exhalation, and complete downstream occlusion. Results Our bench study found that high flow rate therapy did not elevate airway pressures to a level that would result in gastric distention and potential aspiration. In the open mouth test, the pressure ranged from minimum 0.2 to maximum of 1.3 cmH2O, and from minimum of 0.52 to 5.27 cmH2O in the closed mouth test. In the active breathing test, the pressures ranged from minimum 1.5 to 6 cmH2O. In the complete occlusion test, the pressures ranged from minimum 0.37 to 4.49 cmH2O. Conclusion Flows provided during HFNC therapy do not pose a hazard of creating high pressures which exceed esophageal opening pressure and pose a risk of gastric distention. The higher flow rates may reduce the risk associated with the potential false positive prediction of HFNC failure when therapy is not set to match the patient’s inspiratory peak flow demand. The benefit of higher flows to match the inspiratory demand provides a rarely recognized additional benefit of improving the accuracy of predictive indices such as the ROX index and allows for high flow therapy to more fully achieve its intended use.

Pressure and tidal volume delivery in extremely preterm infants at birth using different t-piece resuscitation devices

Infants <28weeks' gestation in need of inflations at birth were recorded with Respiratory Function Monitor. Two devices were used for resuscitation. Peak Inspiratory Pressure spikes were visible in all inflations with GE Panda and in none with Neo-Puff. There was no significant difference in mean Vte/kg between GE Panda and Neo-Puff.

Modeling of pulmonary deposition of agents of open and fixed dose triple combination therapies through two different low-resistance inhalers in COPD: a pilot study.

Inhalation therapy is a cornerstone of treating patients with chronic obstructive pulmonary disease (COPD). Inhaler devices might influence the effectiveness of inhalation therapy. We aimed to model and compare the deposition of acting agents of an open and a fixed dose combination (FDC) triple therapy and examine their repeatability. We recruited control subjects (Controls, n = 17) and patients with stable COPD (S-COPD, n = 13) and those during an acute exacerbation (AE-COPD, n = 12). Standard spirometry was followed by through-device inhalation maneuvers using a pressurized metered dose inhaler (pMDI) and a soft mist inhaler (SMI) to calculate deposition of fixed dose and open triple combination therapies by numerical modeling. Through-device inspiratory vital capacity (IVCd) and peak inspiratory flow (PIFd), as well as inhalation time (tin) and breath hold time (tbh) were used to calculate pulmonary (PD) and extrathoracic deposition (ETD) values. Deposition was calculated from two different inhalation maneuvers. There was no difference in forced expiratory volume in 1 s (FEV1) between patients (S-COPD: 42 ± 5% vs. AE-COPD: 35 ± 5% predicted). Spiriva® Respimat® showed significantly higher PD and lower ETD values in all COPD patients and Controls compared with the two pMDIs. For Foster® pMDI and Trimbow® pMDI similar PD were observed in Controls, while ETD between Controls and AE-COPD patients did significantly differ. There was no difference between COPD groups regarding the repeatability of calculated deposition values. Ranking the different inhalers by differences between the two deposition values calculated from separate maneuvers, Respimat® produced the smallest inter-measurement differences for PD. Our study is the first to model and compare PD using pMDIs and an SMI as triple combination in COPD. In conclusion, switching from FDC to open triple therapy in cases when adherence to devices is maintanined may contribute to better therapeutic effectiveness in individual cases using low resistance inhalers.

ABOLITION OF SAGITTAL T7-T10 DYNAMICS DURING FORCED VENTILATION IN LENKE 1A AIS PATIENTS AS COMPARED WITH HEALTHY SUBJECTS: AN UNDERLYING FACTOR OF RESPIRATORY LIMITATION IN AIS

To analyze the dynamics of the thoracic spine during deep breathing in AIS patients and in healthy matched controls.Case-control cross-sectional study. 20 AIS patients (18 girls, Cobb angle, 54.7±7.9°; Risser 1.35±1.2) and 15 healthy volunteers (11 girls) matched in age (12.5 versus 15.8 yr. mean age) were included. In AIS curves, the apex was located in T8 (14) and T9 (6). Conventional sagittal radiographs of the whole spine were performed at maximal inspiration and expiration. The ROM of each spinal thoracic functional segment (T1-T7, T7-T10, T10-T12), the global T1–T12 ROM were measured. Respiratory function was assess by forced vital capacity (FVC), expiratory volume (FEV1), FEV1/FVC, inspiratory vital capacity (IVC) and peak expiratory flow (PEF).In healthy subjects, the mean T1–T12 ROM during forced breathing was 16.7±3.8. AIS patients showed a T1-T12 ROM of 1.1±1.5 (p&lt;0.05) indicating a sagittal stiffness of thoracic spine. A wide T7–T10 ROM (15.3±3.0) was found in healthy controls (91.6% of the T1–T12 ROM). AIS patients showed only 0.4±1.4 ROM at T7-T10 (36.4% of the T1–T12 ROM) (p&lt;0.001). There was a significant correlation between T7-T10 ROM and IVC.Lenke 1A AIS patients show a restriction of the thoracic spine motion with an almost complete abolition of T7-T10 ROM, a crucial segment participating in the deep breathing. T7-T10 stiffness could explain the ventilatory limitations found in AIS patients.

Respiratory Function Tolerance of Rats with Vaying Degrees of Thoracic Volume Reduction.

To compare the effects of respiratory function on different degrees of reduced thoracic volume and evaluate the tolerance of rats with reduced thoracic volume, and to assess the feasibility of thoracic volume as a measure of the severity of rib fractures. A total of 24 10-week-old female Sprague-Dawley (SD) rats were randomly divided into four groups (n=6 in each group) according to the displacement degree of bilateral rib fractures (2, 4, 6, and 8 mm). The respiratory function of the rats（Tidal volume, Inspiration time, Expiration time, Breath rate, Minute volume, Peak inspiration flow) measured via whole-body barometric plethysmography before and after operation for 14 consecutive days. Respiratory function parameters of each group were analyzed. Chest CT scans were performed before and 14 days after operation, after that we reconstructed three-dimensional of the thoracic and lung and measured their volumes by computer software. We calculated the percentage of thoracic and lung volume reduction after operation. At the 14th day after the operation, the decline of thoracic volume rates of in the 2, 4, 6, and 8 mm groups were 5.20%, 9.01%, 16.67%, and 20.74%, respectively. The 8 mm group showed a significant reduction in lung volume. The postoperative tidal volumes were lower in each of the groups than the baseline values before the operation. The tidal volume of the 2 mm group gradually recovered after the operation and returned to a normal level (1.54 ± 0.07 mL) at 14th day after the operation. The tidal volume of the 4, 6, and 8 mm groups recovered gradually after the operation, but did not return to baseline level at the 14th day. In particular, the tidal volume of the 8 mm group was significantly lower than that of the other groups during the 14 days (1.23 ± 0.12 mL, p < 0.05). There were no significant changes in the inspiratory and expiratory times, peak inspiratory and expiratory flows, respiratory rate, and minute ventilation during the 14 days after the operation in each group. Displaced rib fractures lead to thoracic collapse and reduced thoracic volume, which can affect tidal volume in rats. The greater the decrease of thoracic volume, the more obvious the decrease of early tidal volume. The thoracic volume can be used as an objective parameter to evaluate the severity of multiple rib fractures. Early operation to restore thoracic volume may improve early respiratory function. Decreased thoracic volume affected respiratory function and can be compensated and recovered in the long term.

ESTROGEN ALLEVIATES POSTHEMORRHAGIC SHOCK MESENTERIC LYMPH-MEDIATED LUNG INJURY THROUGH AUTOPHAGY INHIBITION.

Background: Hemorrhagic shock-induced acute lung injury (ALI) is commonly associated with the posthemorrhagic shock mesenteric lymph (PHSML) return. Whether excessive autophagy is involved in PHSML-mediated ALI remains unclear. The relationship between estrogen treatment and PHSML or autophagy needs to verify. The current study will clarify the role of estrogen in reducing PHSML-mediated ALI through inhibition of autophagy. Methods: First, a hemorrhagic shock model in conscious rats was used to observe the effects of 17β-estradiol (E2) on intestinal blood flow, pulmonary function, intestinal and pulmonary morphology, and expression of autophagy marker proteins. Meanwhile, the effect of PHSML and autophagy agonist during E2 treatment was also investigated. Secondly, rat primary pulmonary microvascular endothelial cells were used to observe the effect of PHSML, PHSML plus E2, and E2-PHSML (PHSML obtained from rats treated by E2) on the cell viability. Results: Hemorrhagic shock induced intestinal and pulmonary tissue damage and increased wet/dry ratio, reduced intestinal blood flow, along with pulmonary dysfunction characterized by increased functional residual capacity and lung resistance and decreased inspiratory capacity and peak expiratory flow. Hemorrhagic shock also enhanced the autophagy levels in intestinal and pulmonary tissue, which was characterized by increased expressions of LC3 II/I and Beclin-1 and decreased expression of p62. E2 treatment significantly attenuated these adverse changes after hemorrhagic shock, which was reversed by PHSML or rapamycin administration. Importantly, PHSML incubation decreased the viability of pulmonary microvascular endothelial cells, while E2 coincubation or E2-treated lymph counteracted the adverse roles of PHSML. Conclusions: The role of estrogen reducing PHSML-mediated ALI is associated with the inhibition of autophagy.

In vivo measurements of lung function using respiratory-gated micro-computed tomography in a smoke-exposure model of chronic obstructive pulmonary disease.

We hypothesize that in vivo respiratory-gated micro computed tomography (micro-CT) imaging can noninvasively provide structural and functional information about the lungs in a cigarette-exposure model of chronic obstructive pulmonary disease in mice. Female C57BL/6 mice were exposed to cigarette smoke or ambient air for 1, 3, or 6 months. Each mouse received a respiratory-gated micro-CT scan at baseline and another scan following the exposure period, while anaesthetized and free-breathing. Images were obtained representing end-expiration and peak inspiration, and measurements were performed to characterize the lung structure and compute functional metrics. Following the final micro-CT session, the mice were euthanized and the lungs prepared for histology. Following 6 months of smoke-exposure, the mice exhibited larger increases in end-expiration lung volume and functional residual capacity, and a reduction in weight gain when compared with air-exposed mice. The histogram of CT numbers in the lung obtained during end-expiration also showed a shift to lower CT numbers following 6 months of smoke-exposure, indicating increased air content within the lungs. The metrics suggested air-trapping in the lung, which is consistent with emphysema. In the 3-month exposure group, only the reduction in weight gain was significant compared with the air-exposed group. Histological analysis confirmed that the 6-month smoke-exposed mice likely developed centrilobular emphysema as measured by the mean linear intercept. Respiratory-gated micro-CT imaging of free-breathing mice at multiple respiratory phases is noninvasive and provides additional information about lung structure and function that complements postmortem techniques and could be used to monitor changes over time.

Analysis of physical function, muscle strength, and pulmonary function in surgical cancer patients: a prospective cohort study.

The aim of this study was to investigate mobility, physical functioning, peripheral muscle strength, inspiratory muscle strength and pulmonary function in surgical cancer patients admitted to an intensive care unit (ICU). We conducted a prospective cohort study with 85 patients. Mobility, physical functioning, peripheral muscle strength, inspiratory muscle strength, and pulmonary function were assessed using the following tests: ICU Mobility Scale (IMS); Chelsea Critical Care Physical Assessment (CPAx); handgrip strength and Medical Research Council Sum-Score (MRC-SS); maximal inspiratory pressure (MIP) and S-Index; and peak inspiratory flow, respectively. The assessments were undertaken at ICU admission and discharge. The data were analyzed using the Shapiro-Wilk and Wilcoxon tests and Spearman's correlation coefficient. Significant differences in inspiratory muscle strength, CPAx, grip strength, MRC-SS, MIP, S-Index, and peak inspiratory flow scores were observed between ICU admission and discharge. Grip strength showed a moderate correlation with MIP at admission and discharge. The findings also show a moderate correlation between S-Index scores and both MIP and peak inspiratory flow scores at admission and a strong correlation at discharge. Patients showed a gradual improvement in mobility, physical functioning, peripheral and inspiratory muscle strength, and inspiratory flow during their stay in the ICU.

Do Ultrasound Based Quantitative Hepatic Fat Content Measurements Have Differences Between Respiratory Phases?

The recently developed ultrasound based tools using attenuation coefficient (AC) and scatter distribution coefficient (SDC) values can be used to quantify hepatic fat content in patients with non-alcoholic fatty liver disease (NAFLD). However, currently the impact of respiratory phase on these measurements is not known. The purpose of this study is to compare AC and SDC measurements acquired at peak inspiration and end expiration phases. AC and SDC measurements were obtained in 50 patients with NAFLD. Tissue Attenuation Imaging (TAI) and Tissue Scatter Distribution Imaging (TSI) tools were utilized to measure AC and SDC values, respectively. Five measurements were performed at respiratory phases using TAI and TSI tools and the median values were noted. Subgroup analyses were performed and Wilcoxon signed rank test was used for comparison of the measurements. The median values of the AC measurements at peak inspiration and end expiration phases were 0.87 dB/cm/MHz and 0.89 dB/cm/MHz, respectively. The median values of the SDC measurements at peak inspiration and end expiration phases were 97.91 and 96.62, respectively. There were no statistically significant differences in AC and SDC measurements between the respiratory phases except for AC measurements in BMI <30 kg/m2 subgroup. Our results revealed that respiratory phases have no impact on SDC measurements. However, while the AC measurements in BMI ≥30 kg/m2 subgroup showed no significant difference, there was a significant difference in AC measurements in BMI <30 kg/m2 subgroup between the respiratory phases.

Changes in pontine and preBötzinger/Bötzinger complex neuronal activity during remifentanil-induced respiratory depression in decerebrate dogs.

Introduction: In vivo studies using selective, localized opioid antagonist injections or localized opioid receptor deletion have identified that systemic opioids dose-dependently depress respiratory output through effects in multiple respiratory-related brainstem areas. Methods: With approval of the subcommittee on animal studies of the Zablocki VA Medical Center, experiments were performed in 53 decerebrate, vagotomized, mechanically ventilated dogs of either sex during isocapnic hyperoxia. We performed single neuron recordings in the Pontine Respiratory Group (PRG, n = 432) and preBötzinger/Bötzinger complex region (preBötC/BötC, n = 213) before and during intravenous remifentanil infusion (0.1-1mcg/kg/min) and then until complete recovery of phrenic nerve activity. A generalized linear mixed model was used to determine changes in Fn with remifentanil and the statistical association between remifentanil-induced changes in Fn and changes in inspiratory and expiratory duration and peak phrenic activity. Analysis was controlled via random effects for animal, run, and neuron type. Results: Remifentanil decreased Fn in most neuron subtypes in the preBötC/BötC as well as in inspiratory (I), inspiratory-expiratory, expiratory (E) decrementing and non-respiratory modulated neurons in the PRG. The decrease in PRG inspiratory and non-respiratory modulated neuronal activity was associated with an increase in inspiratory duration. In the preBötC, the decrease in I-decrementing neuron activity was associated with an increase in expiratory and of E-decrementing activity with an increase in inspiratory duration. In contrast, decreased activity of I-augmenting neurons was associated with a decrease in inspiratory duration. Discussion: While statistical associations do not necessarily imply a causal relationship, our data suggest mechanisms for the opioid-induced increase in expiratory duration in the PRG and preBötC/BötC and how inspiratory failure at high opioid doses may result from a decrease in activity and decrease in slope of the pre-inspiratory ramp-like activity in preBötC/BötC pre-inspiratory neurons combined with a depression of preBötC/BötC I-augmenting neurons. Additional studies must clarify whether the observed changes in neuronal activity are due to direct neuronal inhibition or decreased excitatory inputs.

Design and Build a Ventilator Tester with a Peak Inspiratory Flow Waveform Display as Validation using the F1031V Sensor

The ventilator is a supporter of respiratory needs which is very important for the patient so that there are several parameters that must be monitored specifically, such as the measurement of pressure and flow rate used in the ventilator system, the accuracy of which must be in accordance with the accuracy of the respirator. One of the important parameters to monitor is PIF (Peak Inspiratory Flow) which is the peak inspiratory flow rate given through the ventilator. PIF that is too high or too low can cause adverse effects on the patient. PIF monitoring can be seen through the PIF value and waveform on the PIF. Monitoring the waveform of the PIF will be very useful to improve the results of using the ventilator. The purpose of this research is to get the accuracy and precision of the sensor to display the waveform of the ventilator output. The procedure carried out is to use the F1031V sensor to detect the flow generated by the ventilator and then detect the PIF value and PIF waveform. From this research, the measurement of accuracy and precision of the F1031V sensor to detect PIF and generate a waveform graph is said to be good. This is because the highest error value is ±2.04% at the 20 LPM setting. While the value of the largest standard deviation at the 30 LPM setting is 1.517 and the greatest uncertainty value at the 30 LPM setting is 0.061. Then, the largest correction value is found in the setting of 20 LPM and 30 LPM, namely 0.4. PIF monitoring is carried out to maximize patient care and reduce the breakdown time on the ventilator.

Ventilator hyperinflation – what settings generate an expiratory flow rate bias?

ObjectivesTo determine which mechanical ventilation settings influence the attainment of expiratory flow rate characteristics that may promote secretion mobilisation during ventilator hyperinflation (VHI). DesignProspective, single centre study. SettingIntensive care unit, tertiary metropolitan hospital. ParticipantsTwenty-four patients receiving mechanical ventilation. InterventionsPatients were recruited to either a low PEEP or high PEEP group (5–9 cmH2O or 10–15 cmH2O PEEP respectively). Each group had three hyperinflation protocols applied. Main outcome measuresPeak inspiratory flow rates (PIFR) and peak expiratory flow rates (PEFR) were measured and reported as PIFR/PEFR of less than or equal to 0.9; a PEFR-PIFR greater than or equal to 33 L/min; and PEFR greater than or equal to 40 L/min. ResultsIn both the low and high PEEP groups, VHI protocols using volume-controlled ventilation were significantly better at generating expiratory flow rate bias compared to pressure-controlled or Pressure Support ventilation. An expiratory flow rate bias was also achieved when VHI was performed in volume-controlled ventilation with either a peak inspiratory pressure target of 35 cmH2O or a driving pressure of 20 cmH2O. Median heart rate and blood pressure values did not change during VHI, but transient reductions in blood pressure were present in six participants (25%). ConclusionsVHI performed using volume-controlled ventilation was more effective than pressure-controlled or Pressure Support ventilation to generate an expiratory flow rate bias. Contribution of the PaperMechanical ventilator settings can be altered to perform hyperinflation and achieve expiratory flow rate properties that may increase the mobilisation of airway secretions. The results demonstrate that to achieve these properties:•Volume-controlled ventilation appears superior to pressure-controlled and Pressure Support ventilation.•Delivering volume-controlled breaths to a volume that result in a peak pressure of 35 cmH2O or using a driving pressure of 20 cmH2O appear to be equally effective.•Limiting the change in pressure to 20 cmH2O results in significantly lower tidal volumes and may still be effective for airway clearance in people on mechanical ventilation with either high or low PEEP.

O054 Genioglossus neural drive and upper airway dilation in people with obstructive sleep apnoea during wakefulness

Abstract Introduction Genioglossus neural drive and the ensuing tongue dilatory movement may be dissociated in obstructive sleep apnoea (OSA), but this has not been studied. This study aimed to investigate this relationship and its potential role in OSA pathophysiology. Methods During awake nasal breathing in the supine position, inspiratory tongue dilatory movement, quantified with tagged magnetic resonance imaging, and inspiratory peak genioglossus electromyography (EMG) normalised to the maximum voluntary contraction (tongue protrusion), were measured in 4 tongue neuromuscular compartments from 8 controls [apnea-hypopnea index (AHI)&amp;lt;5 events/h] and 34 patients with untreated OSA [AHI&amp;gt;10 events/h]. Results Although larger inspiratory dilatory movement was associated with increased drive to genioglossus (partial Spearman, r=0.23, p=0.016, n=115/68% of compartments), in 14% of the compartments (n=16), there was a large dilatory (&amp;gt;1mm) movement but minimal EMG (&amp;lt;4th percentile). This occurred only in the horizontal compartment. In another group of 18 compartments (16%), there was a large peak EMG (&amp;gt;4th percentile) but minimal dilatory movement (&amp;lt;1mm). This occurred more commonly in the oblique compartments. Dissociation between the amplitude of the peak EMG and inspiratory tongue dilatory movement was most commonly seen in severe OSA patients (AHI&amp;gt;30 events/h, Fisher's exact test, p=0.047). Conclusions Inspiratory tongue dilatory function generally remains closely linked to muscle drive during wakefulness, with larger movement associated with higher peak EMG. However, for approximately one-third of the neuromuscular tongue compartments, neural drive was dissociated from the dilatory motion in severe OSA patients. This may contribute to OSA pathogenesis and have implications for neural stimulation therapy targets.

Pectus excavatum in motion: dynamic evaluation using real-time MRI

ObjectivesThe breathing phase for the determination of thoracic indices in patients with pectus excavatum is not standardized. The aim of this study was to identify the best period for reliable assessments of morphologic indices by dynamic observations of the chest wall using real-time MRI.MethodsIn this prospective study, patients with pectus excavatum underwent morphologic evaluation by real-time MRI at 3 T between January 2020 and June 2021. The Haller index (HI), correction index (CI), modified asymmetry index (AI), and modified eccentricity index (EI) were determined during free, quiet, and forced breathing respectively. Breathing-related differences in the thoracic indices were analyzed with the Wilcoxon signed-rank test. Motion of the anterior chest wall was analyzed as well.ResultsA total of 56 patients (11 females and 45 males, median age 15.4 years, interquartile range 14.3–16.9) were included. In quiet expiration, the median HI in the cohort equaled 5.7 (4.5–7.2). The median absolute differences (Δ) in the thoracic indices between peak inspiration and peak expiration were ΔHI = 1.1 (0.7–1.6, p < .001), ΔCI = 4.8% (1.3–7.5%, p < .001), ΔAI = 3.0% (1.0–5.0%, p < .001), and ΔEI = 8.0% (3.0–14.0%, p < .05). The indices varied significantly during different inspiratory phases, but not during expiration (p > .05 each). Furthermore, the dynamic evaluation revealed three distinctive movement patterns of the funnel chest.ConclusionsReal-time MRI reveals patterns of chest wall motion and indicate that thoracic indices of pectus excavatum should be assessed in the end-expiratory phase of quiet expiration.Key Points• The thoracic indices in patients with pectus excavatum depend on the breathing phase.• Quiet expiration represents the best breathing phase for determining thoracic indices.• Real-time MRI can identify different chest wall motion patterns in pectus excavatum.

NOVEL INSIGHTS GAINED FROM AN INTEGRATED ELECTRONIC INHALER IN PATIENTS WITH SEVERE ASTHMA TREATED WITH BIOLOGICS

NOVEL INSIGHTS GAINED FROM AN INTEGRATED ELECTRONIC INHALER IN PATIENTS WITH SEVERE ASTHMA TREATED WITH BIOLOGICS

A model of transient laryngeal hemiplegia in dogs through conduction blockade of the recurrent laryngeal nerve.

To create a model of transient unilateral laryngeal paralysis (LP) that will allow the study of cricoarytenoideus dorsalis dysfunction and a method for quantification of varying degrees of LP in dogs. 5 castrated male research Beagles. Between January and February 2018, dogs were anesthetized and instrumented with a laryngeal mask airway and a flexible endoscope to record the rima glottidis. The left or right recurrent laryngeal nerve (RLn) was localized using ultrasonography and electrical stimulation, then conduction blockade was induced with perineural lidocaine. The normalized glottal gap area (NGGA) was measured before and every 15 minutes after the block. Inspired 10% carbon dioxide (CO2) was administered for 1 minute at each sampling time. The inspiratory increase in NGGA (total and each side) was measured at peak inspiration. The change in hemi-NGGA for the control side versus the anesthetized side was evaluated with a mixed-effect model. During CO2 stimulation, the increase in inspiratory hemi-NGGA was consistently less (P < .001) for the treated side (-8% to 13%) versus the control side (49% to 82%). A compensatory increase (larger than at baseline) in the control hemi-NGGA was observed. The total NGGA remained unaffected. Unilateral local anesthesia of the RLn produced transient unilateral LP with a compensatory increase in the hemi-NGGA for the contralateral side. This model could facilitate the evaluation of respiratory dynamics, establishment of a grading system, and collection of other important information that is otherwise difficult to obtain in dogs with LP.

Respiratory-Induced Amplitude Modulation of Forcecardiography Signals.

Forcecardiography (FCG) is a novel technique that records the weak forces induced on the chest wall by cardio-respiratory activity, by using specific force sensors. FCG sensors feature a wide frequency band, which allows us to capture respiration, heart wall motion, heart valves opening and closing (similar to the Seismocardiogram, SCG) and heart sounds, all simultaneously from a single contact point on the chest. As a result, the raw FCG sensors signals exhibit a large component related to the respiratory activity, referred to as a Forcerespirogram (FRG), with a much smaller, superimposed component related to the cardiac activity (the actual FCG) that contains both infrasonic vibrations, referred to as LF-FCG and HF-FCG, and heart sounds. Although respiration can be readily monitored by extracting the very low-frequency component of the raw FCG signal (FRG), it has been observed that the respiratory activity also influences other FCG components, particularly causing amplitude modulations (AM). This preliminary study aimed to assess the consistency of the amplitude modulations of the LF-FCG and HF-FCG signals within the respiratory cycle. A retrospective analysis was performed on the FCG signals acquired in a previous study on six healthy subjects at rest, during quiet breathing. To this aim, the AM of LF-FCG and HF-FCG were first extracted via a linear envelope (LE) operation, consisting of rectification followed by low-pass filtering; then, the inspiratory peaks were located both in the LE of LF-FCG and HF-FCG, and in the reference respiratory signal (FRG). Finally, the inter-breath intervals were extracted from the obtained inspiratory peaks, and further analyzed via statistical analyses. The AM of HF-FCG exhibited higher consistency within the respiratory cycle, as compared to the LF-FCG. Indeed, the inspiratory peaks were recognized with a sensitivity and positive predictive value (PPV) in excess of 99% in the LE of HF-FCG, and with a sensitivity and PPV of 96.7% and 92.6%, respectively, in the LE of LF-FCG. In addition, the inter-breath intervals estimated from the HF-FCG scored a higher R2 value (0.95 vs. 0.86) and lower limits of agreement (± 0.710 s vs. ±1.34 s) as compared to LF-FCG, by considering those extracted from the FRG as the reference. The obtained results are consistent with those observed in previous studies on SCG. A possible explanation of these results was discussed. However, the preliminary results obtained in this study must be confirmed on a larger cohort of subjects and in different experimental conditions.

What factors influence the R value in data-driven respiratory gating technique? A phantom study.

The R value is adopted as a metric for the effectiveness of the respiratory waveform in the Advanced Motion Free implemented in the PET scanner as the data-driven respiratory gating (DDG) algorithm. The effects of changes in various factors on R values were evaluated by phantom analysis. We used a programmable respiratory motion phantom QUASAR with a sphere filled with an 18F solution. Respiratory motion simulation was performed by changing the sphere diameter, radioactivity concentration, amplitude, respiratory cycle, and respiratory waveform shape. Three evaluations were performed. (1) The power spectra calculated from the input waveforms were evaluated. (2) The effects of changes in the factors on the R value were evaluated. (3) DDG waveforms and inspiratory peak intervals were compared with the input waveform data set. The R values were increased and converged to a certain value as sphere diameter, radioactivity concentration, and amplitude gradually increased. The respiratory cycle showed the highest R value at 7.5 s, and the graph showed an upward convex pattern. The R value of the sinusoid waveform was higher than that of the typical waveform. There was a relationship between the power spectrum of the input waveform and R value. The visual score was also lower in the condition with a lower R value. In cases of no sphere, radioactivity, or motion, and a fast respiratory cycle, peak intervals were not accurately acquired. Factors affecting the R value were sphere diameter, radioactivity concentration, amplitude, respiratory cycle, and respiratory waveform shape.

Accuracy and Sensitivity of Clinical Parameters in Predicting Successful Extubation in Patients with Acute Brain Injury.

Background: Brain injuries are frequent causes of intubation and mechanical ventilation. The aim of this study was to investigate the accuracy and sensitivity of clinical parameters in predicting successful extubation in patients with acute brain injury. Methods: Six hundred and forty-four patients assisted at a high-complexity hospital were recruited. Patients were divided as for successful or failed extubation. The VISAGE score, maximum inspiratory and expiratory pressures, peak cough flow, and airway occlusion pressure at 0.1 s were used as predictors. Logistic regression analyses using ROC-curve identified values of accuracy and sensitivity. The Hosmer–Lemeshow test and the stepwise method calibrated the statistical model. Results: VISAGE score (odds ratio of 1.975), maximum inspiratory pressure (odds ratio of 1.024), and peak cough flow (odds ratio of 0.981) are factors consistent in distinguishing success from failure extubation. The ROC curve presented an accuracy of 79.7% and a sensitivity of 95.8%. Conclusions: VISAGE score, maximum inspiratory pressure and peak cough flow showed good accuracy and sensitivity in predicting successful extubation in patients with acute brain injury. The greater impact of VISAGE score indicates that patients’ neurological profile should be considered in association with ventilatory parameters in the decision of extubation.