Inspiratory Tidal Volume Research Articles

Streamlined Liner of the Pharynx Airway: Randomised Comparison of Size Selection Strategies with Regard to Patient Height versus Thyroid Cartilage Width

Introduction Streamlined Liner of the Pharynx Airway (SLIPA) is a disposable supraglottic airway. There are two strategies to select the size of SLIPA: by height and width of thyroid cartilage. This study compared the utility of the two strategies in selecting the optimal size. Methods One hundred forty-two patients were randomly divided into two groups with size selection by height (H) and the maximal width of the thyroid cartilage (T). The SLIPA size was selected by height in group H, and by the width of thyroid cartilage in group T. After inserting SLIPA, the investigator made note of the oropharyngeal leakage pressure (OLP) and the degree of insertion difficulty. We set the OLP as a primary outcome. In cases of an OLP <15 cmH2O, the investigator manipulated the apparatus to try to reposition it. If air still leaked, another attempt was made using a SLIPA one size larger until an OLP >15 cmH2O was achieved in up to three attempts. After insertion, the investigator measured the inspiratory and expiratory tidal volume. Post-operatively, the presence of blood or regurgitated fluid on the device was evaluated. Results OLP for group T was higher than that of group H (p=0.009). The need for manipulation and the leak fraction was higher in group H than in group T (p=0.008 and 0.034, respectively). The degree of insertion difficulty, number of trials and incidence of blood and regurgitated fluid on the device were similar between the two groups. Conclusions Both the width and height of thyroid cartilage can be used for selecting the optimal SLIPA size. (Hong Kong j.emerg.med. 2015;22:303-311)

Activation of human inspiratory muscles in an upside-down posture

During quiet breathing, activation of obligatory inspiratory muscles differs in timing and magnitude. To test the hypothesis that this coordinated activation can be modified, we determined the effect of the upside-down posture compared with standing and lying supine. Subjects (n=14) breathed through a pneumotachometer with calibrated inductance bands around the chest wall and abdomen. Surface electromyographic activity (EMG) was recorded from the scalene muscles. Crural diaphragmatic EMG and oesophageal and gastric pressures were measured in a subset of six subjects. Quiet breathing and standard lung function manoeuvres were performed. The upside-down posture reduced end-expiratory lung volume. During quiet breathing, for the same inspiratory airflow and tidal volume, ribcage contribution decreased, abdominal contribution increased and transdiaphragmatic pressure swing doubled in the upside-down posture compared to standing (p<0.05). Despite this, crural diaphragm EMG was unchanged, whereas scalene muscle EMG was reduced by ∼half (p<0.05). Thus, the mechanical effect of an upside-down posture differentially affects inspiratory muscle activation.

Stimulation of Respiratory Motor Output and Ventilation in a Murine Model of Pompe Disease by Ampakines.

Pompe disease results from a mutation in the acid α-glucosidase gene leading to lysosomal glycogen accumulation. Respiratory insufficiency is common, and the current U.S. Food and Drug Administration-approved treatment, enzyme replacement, has limited effectiveness. Ampakines are drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses and can increase respiratory motor drive. Recent work indicates that respiratory motor drive can be blunted in Pompe disease, and thus pharmacologic stimulation of breathing may be beneficial. Using a murine Pompe model with the most severe clinical genotype (the Gaa(-/-) mouse), our primary objective was to test the hypothesis that ampakines can stimulate respiratory motor output and increase ventilation. Our second objective was to confirm that neuropathology was present in Pompe mouse medullary respiratory control neurons. The impact of ampakine CX717 on breathing was determined via phrenic and hypoglossal nerve recordings in anesthetized mice and whole-body plethysmography in unanesthetized mice. The medulla was examined using standard histological methods coupled with immunochemical markers of respiratory control neurons. Ampakine CX717 robustly increased phrenic and hypoglossal inspiratory bursting and reduced respiratory cycle variability in anesthetized Pompe mice, and it increased inspiratory tidal volume in unanesthetized Pompe mice. CX717 did not significantly alter these variables in wild-type mice. Medullary respiratory neurons showed extensive histopathology in Pompe mice. Ampakines stimulate respiratory neuromotor output and ventilation in Pompe mice, and therefore they have potential as an adjunctive therapy in Pompe disease.

Monitoring tidal volumes in preterm infants at birth: mask versus endotracheal ventilation

ObjectiveUpper airway distention during mask ventilation could reduce gas volumes entering the lung compared with ventilation via an endotracheal tube. Therefore, respiratory tract volumes were measured in lambs and tidal...

Effects of different levels of pressure support on intra-individual breath-to-breath variability.

Evidence exists that during pressure support ventilation (PSV), the addition of an extrinsic (ie, ventilator-generated) breath-to-breath variability (BBV) of breathing pattern improves respiratory function. If BBV is beneficial per se, choosing the PS level that maximizes it could be considered a valid strategy for conventional PSV. In this study, we evaluated the effect of different PS levels on intrinsic BBV in acutely ill, mechanically ventilated subjects to determine whether a significant relationship exists between PS level and BBV magnitude. Fourteen invasively mechanically ventilated subjects were prospectively studied. PS was adjusted at 20 cm H2O and sequentially reduced to 15, 10, and 5 cm H2O. Arterial blood gas analysis and pressure at 0.1 s after the onset of inspiration (P0.1) were measured at each PS level. Airway and esophageal pressure and air flow were continuously recorded. Peak inspiratory flow, tidal volume (VT), breathing frequency, and pressure-time product (PTP) were calculated on a breath-by-breath basis. The breathing pattern variability was assessed by the coefficient of variation of the time series of VT, peak inspiratory flow, and breathing frequency from ∼ 60 consecutive breath cycles at each PS level. A general linear model for repeated measures was applied, with PS as an independent factor. A significance level of .05 was considered. Despite a large inter-individual difference in all measured variables (P < .001), the coefficient of variation was as low as 30%, and no significant differences in the coefficient of variation of peak inspiratory flow, breathing frequency, and VT between PS levels were observed (P > .15). Additionally, a significant increase in P0.1, PTP, and breathing frequency (P < .01) and a reduction in VT (P < .001) were observed with PS reduction. Despite a significant increase in spontaneous activity with PS reduction, BBV was not influenced by the PS level and was as low as 30% for all evaluated parameters.

Effects of a Sustained Inflation in Preterm Infants at Birth

To assess the clinical effect of an initial sustained inflation of 10 seconds and 25 cmH2O in preterm infants at birth. In this observational study inflation pressures and tidal volumes were recorded with the use of respiratory function monitoring of preterm infants <32 weeks' gestation receiving a sustained inflation. Inspiratory tidal volume (Vti) and expiratory tidal volume (Vte) of sustained inflation and cumulative Vti and Vte of breaths during sustained inflation were determined. Heart rate and oxygen saturation were measured before and after the sustained inflation. Seventy infants were included (median [IQR]: gestational age 29 [27-30] weeks). Mean (SD) sustained inflation duration was 10.5 seconds (2.9 seconds) with positive inflation pressure 24.2 cmH2O (2.3 cmH2O) and positive end-expiratory pressure 6.0 cmH2O (1.8 cmH2O). In 20 of 70 infants, no volumes were delivered during the sustained inflation because of mask leak. No leak occurred in 50 of 70 infants, of whom 36 of 50 breathed during the sustained inflation. In 14 of the infants who did not breathe, Vti and Vte were 0.9 mL/kg (0.4-2.7 mL/kg) and 0.6 mL/kg (0.1-2.0 mL/kg) with a functional residual capacity (FRC) gain of 0.0 (-0.5 to 0.6) mL/kg. In 36 of 50 infants who breathed during the sustained inflation, Vti was 2.9 mL/kg (0.9-9.2 mL/kg) and Vte 3.8 mL/kg (1.0-5.9 mL/kg), whereas cumulative Vti of breaths was 16.4 mL/kg (6.8-23.3 mL/kg) and cumulative Vte of breaths was 5.8 mL/kg (1.2-16.8 mL/kg) with an FRC gain of 7.1 mL/kg (1.7-15.9 mL/kg). Heart rate and oxygen saturation did not increase immediately after the sustained inflation. A sustained inflation of 10 seconds and 25 cmH2O in preterm infants at birth was not effective unless infants breathed. Although large mask leak accounted for approximately one-third of failures, as FRC gain was only associated with breathing, we speculate that active glottic adduction may be responsible for most failures.

The continuum of physiological impairment during treadmill walking in patients with mild-to-moderate COPD: patient characterization phase of a randomized clinical trial.

BackgroundTo have a better understanding of the mechanisms of exercise limitation in mild-to-moderate chronic obstructive pulmonary disease (COPD), we compared detailed respiratory physiology in patients with COPD and healthy age- and sex-matched controls.MethodsData were collected during the pre-treatment, patient characterization phase of a multicenter, randomized, double-blind, crossover study. Patients with COPD met Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 or 2 spirometric criteria, were symptomatic, and had evidence of gas trapping during exercise. All participants completed pulmonary function and symptom-limited incremental treadmill exercise tests.ResultsChronic activity-related dyspnea measured by Baseline Dyspnea Index was similarly increased in patients with GOLD 1 (n = 41) and 2 (n = 63) COPD compared with controls (n = 104). Plethysmographic lung volumes were increased and lung diffusing capacity was decreased in both GOLD groups. Peak oxygen uptake and work rate were reduced in both GOLD groups compared with controls (p<0.001). Submaximal ventilation, dyspnea, and leg discomfort ratings were higher for a given work rate in both GOLD groups compared with controls. Resting inspiratory capacity, peak ventilation, and tidal volume were reduced in patients with GOLD 2 COPD compared with patients with GOLD 1 COPD and controls (p<0.001).ConclusionsLower exercise tolerance in patients with GOLD 1 and 2 COPD compared with controls was explained by greater mechanical abnormalities, greater ventilatory requirements, and increased subjective discomfort. Lower resting inspiratory capacity in patients with GOLD 2 COPD was associated with greater mechanical constraints and lower peak ventilation compared with patients with GOLD 1 COPD and controls.Trial RegistrationClinicalTrials.gov: NCT01072396

Respiratory Inductance Plethysmography—A Rationale for Validity during Exercise

The aim of this study was to provide a rationale for future validations of a priori calibrated respiratory inductance plethysmography (RIP) when used under exercise conditions. Therefore, the validity of a posteriori-adjusted gain factors and accuracy in resultant breath-by-breath RIP data recorded under resting and running conditions were examined. Healthy subjects, 98 men and 88 women (mean ± SD: height = 175.6 ± 8.9 cm, weight = 68.9 ± 11.1 kg, age = 27.1 ± 8.3 yr), underwent a standardized test protocol, including a period of standing still, an incremental running test on treadmill, and multiple periods of recovery. Least square regression was used to calculate gain factors, respectively, for complete individual data sets as well as several data subsets. In comparison with flowmeter data, the validity of RIP in breathing rate (fR) and inspiratory tidal volume (VTIN) were examined using coefficients of determination (R). Accuracy was estimated from equivalence statistics. Calculated gains between different data subsets showed no equivalence. After gain adjustment for the complete individual data set, fR and VTIN between methods were highly correlated (R = 0.96 ± 0.04 and 0.91 ± 0.05, respectively) in all subjects. Under conditions of standing still, treadmill running, and recovery, 86%, 98%, and 94% (fR) and 78%, 97%, and 88% (VTIN), respectively, of all breaths were accurately measured within ± 20% limits of equivalence. In case of the best possible gain adjustment, RIP confidentially estimates tidal volume accurately within ± 20% under exercise conditions. Our results can be used as a rationale for future validations of a priori calibration procedures.

Breathing variability and brainstem serotonergic loss in a genetic model of multiple system atrophy

Breathing disorders like sleep apnea, stridor, and dysrythmic breathing are frequent in patients with multiple system atrophy (MSA). These observations have been related to neurodegeneration in several pontomedullary respiratory nuclei and may explain the occurrence of sudden death. In this study, we sought to determine whether these functional and neuropathological characteristics could be replicated in a transgenic model of MSA. Mice expressing human wild-type α-synuclein under the control of the proteolipid promoter (PLP-αSYN) were compared with age-matched controls. Using whole-body, unrestrained plethysmography, the following breathing parameters were measured: inspiratory and expiratory times, tidal volume, expiratory volume, peak inspiratory and expiratory flows, and respiratory frequency. For each category, the mean, coefficient of variation, and irregularity score were analyzed. Brains were then processed for stereological cell counts of pontomedullary respiratory nuclei. A significant increase in the coefficient of variation and irregularity score was observed for inspiratory time, tidal volume, and expiratory volume in PLP-αSYN mice (P < 0.05). Glial cytoplasmic inclusions were found in the medullary raphe of PLP-αSYN mice, together with a loss of serotonergic immunoreactivity in the raphe obscurus (P < 0.001) and pallidus (P < 0.01). There was a negative correlation between α-synuclein burden and raphe pallidus cell counts (P < 0.05). There was no significant neuronal loss in the pre-Botzinger complex. The PLP-αSYN mouse model replicates the breathing variability and part of the neuronal depletion in pontomedullary respiratory nuclei observed in patients with MSA. Our findings support the use of this model for future candidate drugs in the breathing disorders observed in MSA.

Intraspinal transplantation and modulation of donor neuron electrophysiological activity

Rat fetal spinal cord (FSC) tissue, naturally enriched with interneuronal progenitors, was introduced into high cervical, hemi-resection (Hx) lesions. Electrophysiological analyses were conducted to determine if such grafts exhibit physiologically-patterned neuronal activity and if stimuli which increase respiratory motor output also alter donor neuron bursting. Three months following transplantation, the bursting activity of FSC neurons and the contralateral phrenic nerve were recorded in anesthetized rats during a normoxic baseline period and brief respiratory challenges. Spontaneous neuronal activity was detected in 80% of the FSC transplants, and autocorrelation of action potential spikes revealed distinct correlogram peaks in 87% of neurons. At baseline, the average discharge frequency of graft neurons was 13.0±1.7Hz, and discharge frequency increased during a hypoxic respiratory challenge (p<0.001). Parallel studies in unanesthetized rats showed that FSC tissue recipients had larger inspiratory tidal volumes during brief hypoxic exposures (p<0.05 vs. C2Hx rats). Anatomical connectivity was explored in additional graft recipients by injecting a transsynaptic retrograde viral tracer (pseudorabies virus, PRV) directly into matured transplants. Neuronal labeling occurred throughout graft tissues and also in the host spinal cord and brainstem nuclei, including those associated with respiratory control. These results underscore the neuroplastic potential of host–graft interactions and training approaches to enhance functional integration within targeted spinal circuitry.

Different respiratory behaviors disclosed by induced bronchoconstriction in mild asthma patients

Respiratory responses to bronchoconstriction in asthma have been partially assessed and their significance is unclear. In 44 mild asthma patients we investigated respiratory responses during increasing levels of methacholine-induced bronchoconstriction. Inspiratory muscle activity, tidal volume, inspiratory and expiratory times were continuously monitored; breathing discomfort was rated. Mean inspiratory flow, respiratory frequency and ventilation were calculated. Lung function was assessed prior to and at maximum bronchoconstriction. Bronchoconstriction “dose-dependently” increased inspiratory muscle activity and breathing discomfort (P<0.01). In 37 patients (84.1%), the increase in inspiratory muscle activity was associated with increases in mean inspiratory flow and ventilation (P<0.01) because of selective rises in breathing depth (volume responders), or rate (frequency responders) or both (dual responders). In seven patients (15.9%) ventilation was unchanged. Individual respiratory responses were reproducible. With bronchoconstriction, frequency responders displayed greater hyperinflation and stronger breathing discomfort than volume responders (P<0.01). Analysis of the responses to induced bronchoconstriction disclosed distinctive and reproducible respiratory adjustments that may identify functionally different asthma subpopulations.

In Reply

I thank the authors Giordano, Gravenstein, and Rice for their valuable comments on the subject of “Capnography Outside the Operating Rooms.”1 Due to the limitations of word count for “Clinical Concepts Commentary,” a detailed account of each capnogram was not provided. Given the wider scope of electronic accessibility, the intention of the article was to provide a comprehensive review of the use of capnography outside operating rooms not only to anesthesiologists and certified registered nurse anesthetists, but also to physicians in other specialties and nurses who provide sedation. Therefore, the article was scripted to provide a concise physiologic background and clinical applications of capnography.Giordano et al. raised important comments regarding capnograms 2C and 3A–D of the article.1 Analysis of capnograms 2C and 3A–D in the aforementioned article is a little more complex than the explanation provided by Giordano etal. Regarding 2C, they state that the inspiratory downstroke will sluggishly return to a zero baseline (or a β angle &gt;90 degrees) during inspiratory valve malfunction. This may be true in the typical circumstance described by Giordano et al., where an assumption is made that half of the expiratory gases will enter the inspiratory limb. However in reality, the quantity of expiratory gases entering the inspiratory limb is dependent on the resistance to the flow of expiratory gases in each limb of the circuit. The resistance in turn is dependent on the design of the valves, extent of malfunction of the inspiratory valve, fresh gas flows, and the length of the circuit. In addition, the carbon dioxide concentration across the inspiratory limb is also dependent on turbulent versus laminar flow of expiratory gases and mixing of carbon dioxide–free fresh gases with expiratory gases in the inspiratory limb (expiratory gases do not flow in blocks). For example, if malfunction of the inspiratory valve results in decreased resistance, it is conceivable that more than half of the expiratory gases might enter the inspiratory limb. This, in conjunction with the gas mixing between carbon dioxide–containing expiratory gases and carbon dioxide–free fresh gases may cause the final portion of the inspiratory tidal volume to contain certain amounts of carbon dioxide. Thus, the resulting downstroke of the capnogram (phase 0) will not reach the zero baseline. This was illustrated by me and my colleagues in a case report where we recorded capnograms during inspiratory valve malfunction and the subsequent inspiratory downstrokes did not reach the baseline.2 However, it was also demonstrated by our group that capnograms can apparently appear normal despite substantial rebreathing resulting from inspiratory valve malfunction. However, when respiratory gas flows were superimposed on the capnograms, the significant rebreathing was obvious.3Regarding capnogram 3A–D illustrated in the original article,1 the morphology of capnograms depends, once again, on several factors. These include patient’s respiratory rate, tidal volume, supplementary oxygen flow, gas leaks from the mask resulting in the carbon dioxide washout by the oxygen flow, and more importantly, the site of the carbon dioxide sampling. In capnograms 3A–D, the site of the sampling was adjacent to the inside wall of the mask via an adaptor, and not at the nostril. Therefore, the recorded carbon dioxide concentration does not represent the carbon dioxide concentration at the nostril. The morphology of the capnograms depends on the location of carbon dioxide sampling within the mask and on the washout of carbon dioxide by the supplementary oxygen flow. Unless carbon dioxide measurements are performed at the nostril, it may be difficult to ascertain whether there is rebreathing (although minimal). For example, figure 1A and B from this reply shows a patient undergoing upper gastroinstestinal endoscopy with supplementary oxygen provided via the mask, and end-tidal carbon dioxide monitoring was performed within the nostril using carbon dioxide sampling nasal cannula. The endoscope was inserted via a “U-shaped flap cut” in the mask. In this case, the carbon dioxide rebreathing was zero (fig. 1B) due to the carbon dioxide washout by supplementary oxygen at the nostril. Capnograms during sedation is a good subject for future discussion.

Measurement of respiratory system compliance and respiratory system resistance in healthy dogs undergoing general anaesthesia for elective orthopaedic procedures: Lung compliance and resistance in healthy dogs

Objective The aim of this study was to investigate normal values for the dynamic compliance of the respiratory system (Crs) and respiratory system resistance (Rrs) in mechanically ventilated anaesthetized dogs. Study design Prospective clinical study. Animals Forty healthy dogs undergoing elective orthopaedic surgery. Body weight was (mean ± SD) 26.8 ± 10.7 kg (range: 1.9–45.0 kg), age 4.7 ± 2.9 years (range: 0.1–10.6 years). Methods Dogs were premedicated with acepromazine and methadone administered intramuscularly and anaesthesia induced with propofol intravenously. After endotracheal intubation the dog's lungs were connected to an appropriate breathing system depending on body weight and isoflurane in oxygen administered for maintenance of anaesthesia. The lungs were ventilated mechanically with variables set to maintain normocapnia (end‐tidal carbon dioxide concentration 4.7–6.0 kPa). Peak inspiratory pressure, Crs, Rrs, tidal volume, respiratory rate and positive end‐expiratory pressure were recorded at 5, 30, 60, 90 and 120 minutes after start of mechanical ventilation. Cardiovascular variables were recorded at time of collection of respiratory data. Results General additive modeling revealed the following relationships: Crs = [0.895 × body weight (kg)] + 8.845 and Rrs = [−0.0966 × body weight (kg)] + 6.965. Body weight and endotracheal tube diameter were associated with Crs (p < 0.001 and p = 0.002 respectively) and Rrs (p = 0.017 and p = 0.002 respectively), body weight being linearly related to Crs and inversely to Rrs. Conclusion and clinical relevance Body weight was linearly related to Crs while Rrs has an inverse linear relationship with body weight in mechanically ventilated dogs. The derived values of Crs and Rrs may be used for monitoring of lung function and ventilation in healthy dogs under anaesthesia.

Effect of slow deep breathing (6 Breaths/Min) on pulmonary function in healthy volunteers

Objective: We designed this study to test the hypothesis that whether 10 minutes of slow deep breathing have any effect on pulmonary function in healthy volunteers. The main objective was to study the immediate effect of slow deep breathing on Forced vital capacity (FVC), Forced expiratory volume in the first second (FEV1), Forced expiratory volume percent (FEV1/FVC%), Peak expiratory flow rate (PEFR), Forced expiratory flow 25-75%(FEF25-75%), Maximum voluntary ventilation (MVV), Slow vital capacity (SVC), Expiratory reserve volume (ERV), Inspiratory reserve volume (IRV) and Tidal volume (TV). Methodology: Following 5 minutes sitting rest in the lab, Forced vital capacity (FVC), Forced expiratory volume in the first second (FEV1), Forced expiratory volume percent (FEV1/FVC%), Peak expiratory flow rate (PEFR), Forced expiratory flow 25-75% (FEF25-75%), Maximum voluntary ventilation (MVV), Slow vital capacity (SVC), Expiratory reserve volume (ERV), Inspiratory reserve volume (IRV) and Tidal volume (TV). The same parameters were recorded following Regular Spontaneous Breathing (RSB) and Slow Deep Breathing (6 breaths/min). Results and Conclusion: There was significant increase in FVC (p<0.0059), FEV1 (p<0.026), PEFR (p<0.02), FEF25-75% (p<0.0006), SVC (p<0.002), ERV (p<0.033), IRV (p<0.025) and TV (p<0.0001) after practicing SDB compared to RSB. Slow deep breathing may be used as a non-pharmaco therapeutic and safe modality, it can be used as an effective lifestyle adjunct to medical treatment to reduce drug dosage and improve quality of life of the patients.

Acute effects of transcutaneous electrical diaphragmatic stimulation on respiratory pattern in COPD patients: cross-sectional and comparative clinical trial

BackgroundTranscutaneous electrical diaphragmatic stimulation (TEDS) has been used to improve respiratory muscle strength in patients with respiratory muscle weakness. However, this physical therapy resource has not been studied in chronic obstructive pulmonary disease (COPD). ObjectiveTo evaluate the respiratory pattern during one session of TEDS in COPD patients. MethodFifteen COPD patients participated in one TEDS session for plethysmographic analysis and assessment of peripheral oxygen saturation (SpO2) and heart rate (HR). After the session, patients were divided into two groups: Responder (R; n=9) and Non-Responder (NR; n=6) to TEDS. Statistic analysis was performed using the Shapiro-Wilk normality test and two-way ANOVA. For the parameters that showed interaction, the Student t test was used (P<0.05). ResultsR group consisted mainly of men, with lower SpO2 and higher HR than NR group. When time (before and during) and groups (R and NR) were compared (interaction), there were differences in the parameters minute ventilation (Vent), inspiratory tidal volume (ViVol), expiratory tidal volume (VeVol), and respiratory rate (Br/M). In the intergroup comparison, differences were observed in the parameters Vent, ViVol, and VeVol. A significant effect was also observed for time in change in end-expiratory lung volume level (qDEEL), phase relation during inspiration (PhRIB); phase relation during expiration (PhREB); phase relation of entire breath (PhRTB), and phase angle (PhAng). During TEDS, there was an increase in SpO2 and a reduction in HR in both groups. ConclusionsThe most hypoxemic group with greater HR responded to TEDS and there was interaction between group and time of analysis for the pulmonary volumes. The time factor had an influence on the two groups with an increase in thoracoabdominal asynchrony.

Immediate effect of suryanadi pranayama on pulmonary function (ventilatory volumes and capacities) in healthy volunteers

we found only effects of at least a short term practice extended over a period of a few days to weeks of pranayama (alternate nostril breathing) rather than acute effects of unilateral right nostril breathing (suryanadi pranayama). Keeping this in mind the present study was designed to test the hypothesis that 10 min. of right nostril breathing have any immediate effect on ventilatory volumes and capacities in healthy volunteers. Methodology: Forced vital capacity (FVC), Forced expiratory volume in the first second (FEV1), Forced expiratory volume percent (FEV1/FVC%), Peak expiratory flow rate (PEFR), Forced expiratory flow25-75% (FEF25-75%), Maximum voluntary ventilation (MVV), Slow vital capacity (SVC), Expiratory reserve volume (ERV), Inspiratory reserve volume (IRV) and Tidal volume (TV) were recorded before and after Surya Nadi Pranayama. Results & Conclusion: There was a significant increase in FVC (p<0.0001), FEV1 (p<0.0007), PEFR (p<0.0001), FEF25-75% (p<0.0001), MVV (p<0.0001), SVC (p<0.0001), ERV (0.0006), IRV (p<0.0001) and TV (0.0055) after suryanadi pranayama. The immediate effect of suryanadi pranayama practice showed alleviation of ventilatory capacities and volumes. Any practice that increases PEFR and FEF25–75% is expected to retard the development of COPD’s. The increase in PEFR, vital capacities and flow rates by suryanadi pranayama practice obviously offers an increment in respiratory efficiency and it can be advocated to the patients of early bronchitis and as a preventive measure for COPD.

Effects of three controlled mechanical ventilation modes on rat lung hydrogen peroxide and apoptosis during hemorrhagic shock

Hemorrhagic shock causes a reduction in oxygen supply to tissues leading to increased reactive oxygen species resulting in lung injury. Often mechanical ventilation is required as supportive treatment; however, ventilation can also induce lung injury and apoptosis. The purpose of this study was to examine the effects of three modes of controlled mechanical ventilation: volume control, pressure control, and pressure regulated volume control on lung injury as measured by hydrogen peroxide and apoptosis during hemorrhagic shock. Male Sprague-Dawley rats were randomized to the three controlled mechanical ventilation groups. Hemorrhagic shock was elicited by removing approximately 40% of the blood volume over 30 minutes. The rats were treated with one of three modes of mechanical ventilation with 40% oxygen for 60 minutes. The lungs were removed and measured for hydrogen peroxide and apoptosis based on nuclear differential dye uptake. There were no significant differences in hemodynamics, arterial blood values, peak inspiratory pressures, tidal volume, respiratory rates, and intrathoracic pressures across three groups. However, lung hydrogen peroxide production and apoptosis were significantly increased in volume control and pressure control, compared to pressure-regulated volume control. In this study, early signs of ventilator induced lung injury were not detected using commonly employed clinical measurements. However, when examining lung cellular injury (hydrogen peroxide and apoptosis), we were able to measure significant lung damage in volume control and pressure control, but not pressure-regulated volume control. Thus, our results suggest that pressure-regulated volume control is the preferable mode of mechanical ventilation during hemorrhagic shock.

P259 Preference of Patients with Obstructive Sleep Apnoea Syndrome (OSAS) For Conventional Continuous Positive Airway Pressure(CPAP) or Bi-Level CPAP (CFlex) and Changes in Resistance to Expiration

CFlex (Respironics) Bi-Level device lowers expiratory PAP (EPAP) early in expiration returning EPAP to the set inspiratory PAP (IPAP) before the start of the next inspiration. Most patients with OSAS...

Effect of Lanz Pressure Regulating Valve on Self-sealing Mechanism and Air Leakage Across the Tracheal Tube Cuffs in a Benchtop Model

The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume-low pressure (HVLP) tube cuffs. In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP (P < .05). The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP (P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant. Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.

Manual neonatal ventilation training: a respiratory function monitor helps to reduce peak inspiratory pressures and tidal volumes during resuscitation

Neonatal resuscitation training is considered to be multifarious and includes manual ventilation as an essential competence for any health-care provider. Usually, ventilation is applied with self-inflating bags (SIBs). These devices have been shown to produce highly variable, operator-dependent peak inspiratory pressures (PIPs) and tidal volumes (V(T)). Excessive PIP and V(T) contribute to lung injury. We studied a simple tool to improve resuscitation skills. The objectives of this study were to train healthcare providers to avoid excessive PIP and V(T) by visualizing these values by using a respiratory function monitor (RFM) and to study the sustainability of such a training. Previously untrained medical professionals were educated and trained to ventilate a neonatal preterm manikin. PIP and V(T) were measured with an RFM. Graphical representations of the measurements were displayed during training, but the RFM was blinded during subsequent recordings. Participants were reassessed directly after training and 1 month later. In total, 37 participants were trained and assessed three times during the study. Median PIPs (range) were 32.3 (4.1 – 44) cm H(2)O before training, 17.8 (9.6 – 23.6) cm H(2)O directly after training (P < 0.05), and 18.7 (7.5 – 41.6) cm H(2)O 1 month later, and the values remained low, compared with before training (P < 0.05). Median V(T)s were 6.7 (4.2 – 44) mL before training, 3.5 (1.8 – 7.3) mL directly after training (P < 0.05), and 4.1 (1.9 – 9.7 mL) 1 month after training (P < 0.05). Using a SIB, untrained staff produced excessive PIP and V(T). Training with a simple RFM significantly reduced the occurrence of excessive PIP and V(T). The effect was sustained for at least 1 month.