Expiratory Tidal Volume Research Articles

A novel technique for assessment of post-extubation airway obstruction can successfully replace the conventional cuff leak test: a pilot study

BackgroundPost-extubation airway obstruction is an important complication of tracheal intubation. The cuff leak test is traditionally used to estimate the risk of this complication. However, the cuff leak test parameters are not constant and may depend on the respiratory system and ventilator settings. Furthermore, deflating the cuff also be a risk factor for patient-ventilator asynchrony and ventilator-associated pneumonia.Instead of using the cuff leak test, we measured the pressure of the leak to the upper airway through the gap between the tube and glottis with a constant low flow from the lumen above the cuff without deflating the cuff and called it "pressure above the cuff."The purpose of this study was to investigate whether pressure above the cuff can be used as an alternative to the cuff leak volume.MethodsThis prospective observational study was conducted at Kumamoto University Hospital after obtaining approval from the institutional review board. The pressure above the cuff was measured using an endotracheal tube with an evacuation lumen above the cuff and an automated cuff pressure modulation device. We pumped 0.16 L per minute of air and measured the steady-state pressure using an automated cuff pressure modulation device. Then, the cuff leak test was performed, and the cuff leak volume was recorded. The cuff leak volume was defined as the difference between the expiratory tidal volume with the cuff inflated and deflated. The relationship between the pressure above the cuff and cuff leak volume was evaluated. The patient-ventilator asynchrony during each measurement was also examined.ResultsThe pressure above the cuff was measured, and the cuff leak volume was assessed 27 times. The pressure above the cuff was significantly correlated with the cuff leak volume (r = -0.76, p < 0.001). Patient-ventilator asynchrony was detected in 37% of measurements during the cuff leak test, but not during the pressure above the cuff test.ConclusionsThis study suggests that pressure above the cuff measurement may be a less complicated alternative to the conventional cuff leak test for evaluation of the risk of post-extubation airway obstruction.Trial registrationUniversity Hospital Medical Information Network Clinical Trials Registry (UMIN000039987; March 30, 2020). https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000044604

Effect of Head Rotation on Efficiency of Face Mask Ventilation among Apnoeic Patients: A Cross-sectional Study

Introduction: Respiratory function is crucial in the practice of anaesthesia. An in depth understanding of respiratory physiology is a must because it aids in the proper execution of daily general anaesthesia practice. Head and body postures have long been known to affect the patency of the upper airway. Head extension and a lateral recumbent position help to clear the upper airway. Head rotation is known to expand the upper airway’s cross-sectional area. Aim: To determine the effect of head rotation on efficiency of face mask ventilation among apnoeic patients, by measuring expiratory tidal volume. Materials and Methods: This cross-sectional study was conducted in the Department of Anaesthesiology at Jawaharlal Nehru Medical College, Acharya Vinoba Bhave Rural Hospital, Sawangi, Wardha, Maharashtra, India, from May 2021 to November 2021. Total 40 patients belonging to the age group of 20 to 40 years, American Society of Anaesthesiologists’ (ASA) class I and II, undergoing surgeries requiring general anaesthesia with endotracheal intubation, were selected as study subjects. They were administered inj. fentanyl at a dose of 1 to 2 μg/kg, inj.propofol at a dose of 1 to 2 mg/kg, and inj.vecuronium bromide (0.08 to 0.1 mg/kg). Patients were mask ventilated with pressurecontrolled ventilation, for a total of 3 minutes, during which they were ventilated in a neutral head position for 90 seconds and then rotated for another 90 seconds. Following induction, the expiratory tidal volume was measured every 30 seconds in both postures Software used was Statistical Package for Social Sciences for windows (SPSS Inc., Chicago, IL, USA), version 17.0. A p-value &lt;0.05 was considered statistically significant. Results: The mean age of patients was 48±8.3 years. The 45° head rotation was beneficial to all patients, the mean expiratory tidal volume was 423±62.5 mL in the rotated head position compared to 397±52.5 mL in the neutral head position (p-value=0.045). It was also observed that some individuals profited more than others. Patients with airway obstruction, for example, had a greater VTE at 45° head rotation than in a neutral head position. Conclusion: The most notable conclusion is that in apnoeic adult patients, a 45° head rotation showed a significant enhancement in VTE when compared to a neutral position ofthe head.

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia

The use of capnography for real-time monitoring of mask ventilation during induction of general anaesthesia

An Exploration of Lung Volume Effects on Swallowing in Chronic Obstructive Pulmonary Disease.

Purpose Chronic obstructive pulmonary disease (COPD) limits respiration, which may negatively impact airway safety during swallowing. It is unknown how differences in lung volume in COPD may alter swallowing physiology. This exploratory study aimed to determine how changes in lung volume impact swallow duration and coordination in persons with stable state COPD compared with older healthy volunteers (OHVs). Method Volunteers ≥ 45 years with COPD (VwCOPDs; n = 9) and OHVs (n = 10) were prospectively recruited. Group and within-participant differences were examined when swallowing at different respiratory volumes: resting expiratory level (REL), tidal volume (TV), and total lung capacity (TLC). Participants swallowed self-administered 20-ml water boluses by medicine cup. Noncued (NC) water swallows were followed by randomly ordered block swallowing trials at three lung volumes. Estimated lung volume (ELV) and respiratory-swallow patterning were quantified using spirometry and respiratory inductive plethysmography. Manometry measured pharyngeal swallow duration from onset of base of tongue pressure increase to offset of negative pressure in the pharyngoesophageal segment. Results During NC swallows, the VwCOPDs swallowed at lower lung volumes than OHVs (p = .011) and VwCOPDs tended to inspire after swallows more often than OHVs. Pharyngeal swallow duration did not differ between groups; however, swallow duration significantly decreased as the ELV increased in VwCOPDs (p = .003). During ELV manipulation, the COPD group inspired after swallowing more frequently at REL than at TLC (p = .001) and at TV (p = .002). In conclusion, increasing respiratory lung volume in COPD should improve safety by reducing the frequency of inspiration after a swallow.

Comparison of intraoral mask and classic face mask in terms of ventilation success and practitioners' workload assessments: A randomised crossover study.

Providing effective ventilation of the unconscious patient is an essential skill in every specialty dealing with airway management. In this randomised crossover study aimed to compare intraoral and classic face mask in terms of ventilation success of patients, practitioners' workload and anxiety assessments. Also we analysed potential risk factors of difficult mask ventilation for both masks. In all, 24 anaesthesiology residents and 12 anaesthesiologists participated in the study. Each of the practitioners ventilated four patients with both masks at settled pressure and frequency. Practitioners rated their workload and anxiety related to masks with National Aeronautics and Space Administration Task Load Index score and State Trait Anxiety Inventory scale. Ventilation success was evaluated with Han scale, expiratory tidal volume and leak volume. We analysed potential risk factors of difficult mask ventilation with anthropometric characteristics and STOP-Bang score. Ventilation success rate was superior with intraoral mask comparing to classic face mask in terms of successful ventilation (P=.000) and tidal volume (P=.000). Leak volume in in intraoral mask ventilation was significantly lower than classic face mask (P=.000). Difficult mask ventilation risk factors for classic face mask were high weight (P=.011), neck circumference (95% CI, OR=1.180, P=.002), Mallampati score (P=.029) and high risk of OSAS (P=.001). Difficult mask ventilation risk factors for intraoral mask were high body mass index (95% CI, OR 1.162 P=.006) and Mallampati score (P=.043). The anxiety ratings of practitioners were similar between two masks. The workload rating is higher with intraoral mask comparing to classic face mask. Intraoral mask may be an effective alternative device for bag-valve mask ventilation.

Sustained Inflation Versus Intermittent Positive Pressure Ventilation for Preterm Infants at Birth: Respiratory Function and Vital Sign Measurements

To characterize respiratory function monitor (RFM) measurements of sustained inflations and intermittent positive pressure ventilation (IPPV) delivered noninvasively to infants in the Sustained Aeration of Infant Lungs (SAIL) trial and to compare vital sign measurements between treatment arms. We analyzed RFM data from SAIL participants at 5 trial sites. We assessed tidal volumes, rates of airway obstruction, and mask leak among infants allocated to sustained inflations and IPPV, and we compared pulse rate and oxygen saturation measurements between treatment groups. Among 70 SAIL participants (36 sustained inflations, 34 IPPV) with RFM measurements, 40 (57%) were spontaneously breathing prior to the randomized intervention. The median expiratory tidal volume of sustained inflations administered was 5.3mL/kg (IQR 1.1-9.2). Significant mask leak occurred in 15% and airway obstruction occurred during 17% of sustained inflations. Among 34 control infants, the median expiratory tidal volume of IPPV inflations was 4.3mL/kg (IQR 1.3-6.6). Mask leak was present in 3%, and airway obstruction was present in 17% of IPPV inflations. There were no significant differences in pulse rate or oxygen saturation measurements between groups at any point during resuscitation. Expiratory tidal volumes of sustained inflations and IPPV inflations administered in the SAIL trial were highly variable in both treatment arms. Vital sign values were similar between groups throughout resuscitation. Sustained inflation as operationalized in the SAIL trial was not superior to IPPV to promote lung aeration after birth in this study subgroup. Clinicaltrials.gov: NCT02139800.

Chest Physiotherapy for Mechanically Ventilated Children: A Systematic Review.

The aim of this study was to appraise and summarize the effects of chest physiotherapy in mechanically ventilated children. A systematic review was completed by searching Medline, Embase, Cinahl Plus, PEDro, and Web of Science from inception to February 9, 2021. Studies investigating chest physiotherapy for mechanically ventilated children (0-18 years), in a pediatric intensive care unit were included. Chest physiotherapy was defined as any intervention performed by a qualified physiotherapist. Measurements of effectiveness and safety were included. Exclusion criteria included preterm infants, children requiring noninvasive ventilation, and those in a nonacute setting. Thirteen studies met the inclusion criteria: two randomized controlled trials, three randomized crossover trials, and eight observational studies. The Cochrane risk of bias and the Critical Appraisal Skills Program tools were used for quality assessment. Oxygen saturations decreased after physiotherapy involving manual hyperinflations (MHI) and chest wall vibrations (CWV). Although statistically significant, these results were not of clinical importance. In contrast, oxygen saturations improved after the expiratory flow increase technique; however, this was not clinically significant. An increase in expiratory tidal volume was demonstrated 30 minutes after MHI and CWV. There was no sustained change in tidal volume following a physiotherapy-led recruitment maneuver. Respiratory compliance and dead-space increased immediately after MHI and CWV. Atelectasis scores improved following intrapulmonary percussive ventilation, and MHI and CWV. Evidence to support chest physiotherapy in ventilated children remains inconclusive. There are few high-quality studies, with heterogeneity in interventions and populations. Future studies are required to investigate multiple physiotherapy interventions and the impact on long-term outcomes.

Effects of airway management and tidal volume feedback ventilation during pediatric resuscitation in piglets with asphyxial cardiac arrest

To compare the effect on the recovery of spontaneous circulation (ROSC) of early endotracheal intubation (ETI) versus bag-mask ventilation (BMV), and expiratory real-time tidal volume (VTe) feedback (TVF) ventilation versus without feedback or standard ventilation (SV) in a pediatric animal model of asphyxial cardiac arrest. Piglets were randomized into five groups: 1: ETI and TVF ventilation (10 ml/kg); 2: ETI and TVF (7 ml/kg); 3: ETI and SV; 4: BMV and TVF (10 ml/kg) and 5: BMV and SV. Thirty breaths-per-minute guided by metronome were given. ROSC, pCO2, pO2, EtCO2 and VTe were compared among groups. Seventy-nine piglets (11.3 ± 1.2 kg) were included. Twenty-six (32.9%) achieved ROSC. Survival was non-significantly higher in ETI (40.4%) than BMV groups (21.9%), p = 0.08. No differences in ROSC were found between TVF and SV groups (30.0% versus 34.7%, p = 0.67). ETI groups presented lower pCO2, and higher pO2, EtCO2 and VTe than BMV groups (p < 0.05). VTe was lower in TVF than in SV groups and in BMV than in ETI groups (p < 0.05). Groups 1 and 3 showed higher pO2 and lower pCO2 over time, although with hyperventilation values (pCO2 < 35 mmHg). ETI groups had non significantly higher survival rate than BMV groups. Compared to BMV groups, ETI groups achieved better oxygenation and ventilation parameters. VTe was lower in both TVF and BMV groups. Hyperventilation was observed in intubated animals with SV and with 10 ml/kg VTF.

A multi-centre randomised controlled trial of respiratory function monitoring during stabilisation of very preterm infants at birth

AimTo determine whether the use of a respiratory function monitor (RFM) during PPV of extremely preterm infants at birth, compared with no RFM, leads to an increase in percentage of inflations with an expiratory tidal volume (Vte) within a predefined target range. MethodsUnmasked, randomised clinical trial conducted October 2013 - May 2019 in 7 neonatal intensive care units in 6 countries. Very preterm infants (24–27 weeks of gestation) receiving PPV at birth were randomised to have a RFM screen visible or not. The primary outcome was the median proportion of inflations during manual PPV (face mask or intubated) within the target range (Vte 4–8 mL/kg). There were 42 other prespecified monitor measurements and clinical outcomes. ResultsAmong 288 infants randomised (median (IQR) gestational age 26+2 (25+3–27+1) weeks), a total number of 51,352 inflations were analysed. The median (IQR) percentage of inflations within the target range in the RFM visible group was 30.0 (18.0–42.2)% vs 30.2 (14.8–43.1)% in the RFM non-visible group (p = 0.721). There were no differences in other respiratory function measurements, oxygen saturation, heart rate or FiO2. There were no differences in clinical outcomes, except for the incidence of intraventricular haemorrhage (all grades) and/or cystic periventricular leukomalacia (visible RFM: 26.7% vs non-visible RFM: 39.0%; RR 0.71 (0.68–0.97); p = 0.028). ConclusionIn very preterm infants receiving PPV at birth, the use of a RFM, compared to no RFM as guidance for tidal volume delivery, did not increase the percentage of inflations in a predefined target range. Trial registrationDutch Trial Register NTR4104, clinicaltrials.gov NCT03256578.

Influence of the Bed Head Positioning on the Current Expiratory Volume of Pediatric Patients in Mechanical Ventilation: A Pilot Clinical Controlled Trial

he elevated bed head position is an important therapeutic intervention that can reduce respiratory complications associated with mechanical ventilation. The objective of this study was to evaluate the effects of elevation at the head of the bed on the tidal volume, pressure variables, hemodynamic data and peripheral oxygen saturation in pediatric patients on mechanical ventilation. Methods: In a before-and-after clinical trial, 52 patients of both sexes, with a chronological age of 28 days to 14 years old, were admitted to the pediatric intensive care unit for more than 24 hours. These were positioned at 0º, 30º, 45º and 60º of elevation of the head of the bed. For each position, the expiratory tidal volume, pressure variables, hemodynamic data and peripheral oxygen saturation were evaluated. Results: The patients presented an increase in the expired tidal volume, with the bed head angulation at 30º and 45º. Heart rate increased when the head was positioned at 60º. The peripheral oxygen saturation variable increased in the 30º and 45º positions. The systolic blood pressure variables and diastolic blood pressure showed a progressive increase in the 30º, 45º and 60º positions respectively. Significant effects on increasing the SatO2/FiO2 ratio were observed in the 30º and 45º positions. Conclusion: This study demonstrated a significant increase in expired tidal volume and an increase in the SatO2/FiO2 ratio with the patient positioned at 30º and 45º of elevation of the head of the bed. The peripheral oxygen saturation variable increased in the 30º and 45º positions. The elevated bed head position should be considered when monitoring children during mechanical ventilation.

Electrical Stimulation of Afferent Lumbar Sympathetic Nerve Impacts Cardio‐Respiratory Functions in Anesthetized Rats

The lumbar sympathetic chains (LSC) contain post-ganglionic vasodilator and vasoconstrictor fibers that control hindlimb vascular tone. The LSC also contain dorsal root ganglion afferent fibers whose roles in cardiorespiratory status remain poorly understood. The objective of the present study was to characterize the cardiorespiratory responses elicited by electrical stimulation (ES) of a LSC in urethane-anaesthetized male Sprague-Dawley rats (n=6) instrumented to measure/calculate mean arterial blood pressure (MAP), femoral artery blood flow (FBF) and femoral vascular resistance (FVR), brachial artery blood flow (BBF), and brachial vascular resistances (BVR), upper airway pressure (UAP), diaphragmatic EMG, respiratory frequency, inspiratory (iTV) and expiratory (eTV) tidal volumes. The right LSC was identified at the level of L4-L6 and a bipolar electrode was placed for ES (5 Hz, 0.5 msec duration, 0.5 mA amplitude for 10 sec). LSC stimulation caused a distinct pattern of cardiorespiratory responses including (a) a 12% decrease in MAP, (b) 15% decrease in ipsilateral FVR, (c) a 10% decrease in BVR (all measured at the peak decrease in MAP), (d) a 15% increase in iVT, (e) a 10% increase in eVT, (f) a15% increase in respiratory frequency, and (g) a 9% increase in diaphragmatic EMG activity. The result of this study demonstrates that ES of afferent fibers within the LSC elicits an array of cardiorespiratory changes in anesthetized rats that would be consistent with preparing the rats for exercise and for flight.

The Articulated Oral Airway as an aid to mask ventilation: a prospective, randomized, interventional, non-inferiority study

BackgroundOropharyngeal airways are used both to facilitate airway patency during mask ventilation as well as conduits for flexible scope intubation, though none excel at both. A novel device, the Articulated Oral Airway (AOA), is designed to facilitate flexible scope intubation by active displacement of the tongue. Whether this active tongue displacement also facilitates mask ventilation, thus adding dual functionality, is unknown. This study compared the AOA to the Guedel Oral Airway (GOA) in regards to efficacy of mask ventilation of patients with factors predictive of difficult mask ventilation. The hypothesis was that the AOA would be non-inferior to the GOA in terms of expiratory tidal volumes by a margin of 1 ml/kg, thus demonstrating dual functionality.MethodsIn this randomized controlled clinical trial, fifty-eight patients with factors predictive of difficult mask ventilation were mask ventilated with both the GOA and the AOA. Video of the anesthetic monitors were evaluated by a blinded member of the research team, noting inspiratory and expiratory tidal volumes and expiratory CO2 waveforms.ResultsThe AOA was found to be non-inferior to the GOA at a margin of 1 ml/kg with a mean weight-standardized expiratory tidal measurement 0.45 ml/kg lower (CI: 0.34–0.57) and inspiratory tidal measurement 0.109 lower (CI: − 0.26-0.04). There was no significant difference in expiratory waveforms (p = 0.2639).ConclusionsThe AOA was non-inferior to the GOA for mask ventilation of patients with predictors of difficult mask ventilation and there was no significant difference in EtCO2 waveforms between the groups. These results were consistent in the subset of patients who were initially difficult to mask ventilate.Trial registrationClinicalTrials.gov, NCT03144089, May 2017.

Physiological dead space and alveolar ventilation in ventilated infants

BackgroundDead space is the volume not taking part in gas exchange and, if increased, could affect alveolar ventilation if there is too low a delivered volume. We determined if there were differences in dead space and alveolar ventilation in ventilated infants with pulmonary disease or no respiratory morbidity.MethodsA prospective study of mechanically ventilated infants was undertaken. Expiratory tidal volume and carbon dioxide levels were measured. Volumetric capnograms were constructed to calculate the dead space using the modified Bohr–Enghoff equation. Alveolar ventilation (VA) was also calculated.ResultsEighty-one infants with a median (range) gestational age of 28.7 (22.4–41.9) weeks were recruited. The dead space [median (IQR)] was higher in 35 infants with respiratory distress syndrome (RDS) [5.7 (5.1–7.0) ml/kg] and in 26 infants with bronchopulmonary dysplasia (BPD) [6.4 (5.1–7.5) ml/kg] than in 20 term controls with no respiratory disease [3.5 (2.8–4.2) ml/kg, p < 0.001]. Minute ventilation was higher in both infants with RDS or BPD compared to the controls. VA in infants with RDS or BPD was similar to that of the controls [p = 0.54].ConclusionPrematurely born infants with pulmonary disease have a higher dead space than term controls, which may influence the optimum level during volume-targeted ventilation.ImpactMeasurement of the dead space was feasible in ventilated newborn infants.The physiological dead space was a significant proportion of the delivered volume in ventilated infants.The dead space (per kilogram) was higher in ventilated infants with respiratory distress syndrome or evolving bronchopulmonary dysplasia compared to term controls without respiratory disease.The dead space volume should be considered when calculating the most appropriate volume during volume-targeted ventilation.

Frequency of the requirement of inappropriate uncuffed tracheal tube size for pediatric patients: a retrospective observational analysis

BackgroundThe insertion of inappropriately sized uncuffed endotracheal tubes (ETTs) with a tight seal or presence of air leakage may be necessary in children. This study aimed to analyze the frequency of the requirement of inappropriately sized uncuffed ETT insertion, air leakage after the ETT was replaced with one of a larger size, and factors associated with air leakage after ETT replacement.MethodsPatients under 2 years of age who underwent oral surgery under general anesthesia with uncuffed ETTs between December 2013 and May 2015 were enrolled. The ETT size was selected at the discretion of the attending anesthesiologists. A leak test was performed after intubation. The ETT was replaced when considered necessary. Data regarding the leak pressure (PLeak) and inspiratory and expiratory tidal volumes were extracted from anesthesia records. We considered a PLeak of 10 < PLeak ≤ 30 cmH2O to be appropriate. The frequencies of the requirement of inappropriately sized ETTs, absence of leakage after ETT replacement, ETT size difference, and leak rate were calculated. A logistic regression was performed, with PLeak, leak rate, and size difference included as explanatory variables and presence of leakage after replacement as the outcome variable.ResultsOut of the 156 patients enrolled, 109 underwent ETT replacement, with the requirement of inappropriately sized ETTs being observed in 25 patients (23%). ETT replacement was performed in patients with PLeak ≤ 10 cmH2O; leakage was absent after replacement (PLeak < 30 cmH2O) in 52% of patients (25/48). In the multivariate logistic model, the leak rate before ETT replacement was significantly associated with the presence of leakage after replacement (p = 0.021).ConclusionsInappropriately sized ETTs were inserted in approximately 23% of the patients. The leak rate may be useful to guide ETT replacement.

Prevalence, Proportionality, and Cause of Ventilator Alarms in a Pediatric Intensive Care Setting.

Clinical alarms play an important role in monitoring physiological parameters, vital signs and medical device function in the hospital intensive care environment. Delays in staff response to alarms are well documented as health care providers become desensitized to increased rates of nuisance alarms. Patients can be at increased risk of harm due to alarm fatigue. Current literature suggests alarms from ventilators contribute significantly to nonactionable alarms. A greater understanding of which specific ventilator alarms are most common and the rates at which they occur is fundamental to improving alarm management. A retrospective review was performed on alarms that occurred on the Avea and Servo-i ventilators used in the pediatric ICU and pediatric cardiothoracic ICU at a major metropolitan children's hospital. High- and medium-priority alarms, as classified by the manufacturer, were studied between June 1, 2017, and November 31, 2017. Descriptive data analysis and a 2-proportion z-test were performed to identify proportionality, cause, and prevalence rates in the pediatric ICU and the cardiothoracic ICU. Eleven distinct ventilator alarms were identified during 2,091 d of mechanical ventilation. The Inspiratory Flow Overrange alarm (42.4%) on the Servo-i, Low VTE (20.4%; expiratory tidal volume) and Circuit Integrity alarm (20.0%) on the Avea were the most prevalent causes according to ventilator type. Medium-priority alarms comprised 68.7% of all Servo-i alarms, and high-priority alarms comprised 84% of all Avea alarms. The 2-sample test of proportions was significant for differences between both areas (P < .001). The overall alarm prevalence rate was 22.5 ventilator alarms per ventilator-day per patient. The cause and proportion of alarms varied by ventilator and care unit. High-priority alarms were most common with the Avea and medium-priority alarms for the Servo-i. The overall combined ventilator alarm prevalence rate was 22.5 alarms per ventilator-day per patient.

Cerebral oxygenation and circulatory parameters during pressure-controlled vs volume-targeted mechanical ventilation in extremely preterm infants.

Respiratory distress syndrome (RDS) is the most common cause of respiratory failure of infants born prematurely with very low birth weight (VLBW). Essential elements of RDS management include ventilatory support and endotracheal administration of a surfactant. To assess the effect of volume-targeted compared to pressure-controlled mechanical ventilation (MV) on circulatory parameters and cerebral oxygenation StO2 in extremely preterm infants. This prospective, cross-over trial enrolled neonates born before 28 weeks of gestation. The patients were ventilated for 3 h in pressure-controlled assist-control (PC-AC) mode, followed by 3 h of volume-guarantee assist-control ventilation (VG-AC). Pulse oximetry (saturation (SpO2) and heart rate (HR)), near-infrared spectroscopy (NIRS), StO2, and electrical cardiometry (EC) were used in monitoring of the patients. Twenty preterm infants with a mean gestational age of 26 weeks were studied. The patients' mean postnatal age was 7.7 days. The SpO2 values and HR were comparable during PC-AC and VG-AC. The mean values of peak inspiratory pressure (PIP), mean airway pressure (MAP) and expiratory tidal volume (VTE) were lower, while the respiratory rate (RR) was higher during PC-VG. There were no significant differences in the mean values of StO2, but based on a comparison of the standard deviations (SD) the StO2 variability was significantly lower during VG-AC. The circulatory parameters were comparable. The StO2 is more stable during VG than PC ventilation. These findings support the use of VG mode in premature infants.

Effects of 12-week inspiratory muscle training with low resistance in patients with multiple sclerosis: A non-randomised, double-blind, controlled trial

BackgroundPatients with multiple sclerosis (MS) have respiratory limitations like fatigue or muscle weakness. The aim of the study was to evaluate the effectiveness of a low-intensity protocol with inspiratory muscle training (IMT) to improve respiratory strength, spirometric parameters and dyspnea in patients with MS. MethodsThis study was a controlled, non-randomised, double-blind trial on 67 patients with MS distributed in 2 groups, intervention group (IG) (n = 36) and respiratory exercise group (REG) (n = 31). Over 12 weeks, 5 days/week, 15 min/day all subjects followed a respiratory training program. IG trained with IMT with low resistance (20% maximum inspiratory pressure (MIP) during the first two weeks, 30% MIP after the second week). REG followed a program involving nasal breathing and maximum exhalation. Main outcome measured was inspiratory strength (MIP); secondary outcomes were maximum expiratory pressure (MEP), spirometry, dyspnea and health-related quality of life. ResultsAfter respiratory training, the intervention group improved MIP, MEP, MVV, peak expiratory flow (PEF), tidal volume (TV) and dyspnea, 51%, 36%, 21%,11%, 51% and 19% respectively (p < .001, p < .001, p < .001, p < .05, p < .05, p < .05). The control group improved MIP, MEP, MVV and PEF, 24%, 27%, 28% and 12% respectively (p < .001, p < .001, p < .001, p < .05). Improvements achieved on MIP and dyspnea were significantly higher in IG patients (p=.002, p=.046, respectively). Conclusion12-week inspiratory muscle training with low resistance was more effective than conventional respiratory exercises to improve respiratory strength, spirometric parameters and dyspnea in patients with multiple sclerosis.

Volume guarantee ventilation in neonates treated with hypothermia for hypoxic-ischemic encephalopathy during interhospital transport.

ObjectiveWe investigated if volume guarantee (VG) ventilation in babies with hypoxic-ischemic encephalopathy (HIE) during interhospital transport decreases tidal volumes and prevents hypocapnia.Study designWe computationally collected and analyzed ventilator data of babies ventilated with synchronized intermittent mandatory ventilation (SIMV) with VG (n = 28) or without VG (n = 8).ResultThe expiratory tidal volume of ventilator inflations was lower with SIMV-VG (median [IQR]: 4.9 [4.6–5.3] mL/kg) than with SIMV only (median [IQR]: 7.1 [5.3–8.0] mL/kg, p = 0.01). Babies receiving SIMV-VG had lower peak inflating pressures (median: 10.7 cmH2O, versus 17.5 cmH2O, p = 0.01). There was no significant difference in minute ventilation or in pCO2. Babies with strong spontaneous breathing had a mean PIP < 10 cmH2O but this did not result in adverse events or worsening of acidosis.ConclusionsThe use of VG ventilation in babies with HIE reduces tidal volumes and frequently results in very low inflating pressures without affecting pCO2.

Hyperinflation With Pulmonary Dysfunction in Donor Lungs With Smoking History During Lung Perfusion

BackgroundDonor lungs with smoking history are perfused in ex vivo lung perfusion (EVLP) to expand donor lung pool. However, the impact of hyperinflation of perfused lungs in EVLP remains unknown. The aim of this study was to investigate the significance of hyperinflation, using an ex vivo measurement delta VT, during EVLP in smoker's lungs. Materials and methodsSeventeen rejected donor lungs with smoking history of median 10 pack-years were perfused for 2 h in cellular EVLP. Hyperinflation was evaluated by measuring delta VT = inspiratory − expiratory tidal volume (VT) difference at 1 h. All lungs were divided into two groups; negative delta VT (n = 11, no air-trapping pattern) and positive delta VT (n = 6, air-trapping pattern). Transplant suitability was judged at 2 h. By using lung tissue, linear intercept analysis was performed to evaluate the degree of hyperinflation. ResultsThe positive delta VT group had significantly lower transplant suitability than the negative delta VT group (16 versus 81%, P = 0.035). The positive delta VT group was significantly associated with lower partial pressure of oxygen/fraction of inspired oxygen ratio ratio (278 versus 356 mm Hg, P = 0.049), higher static compliance (119 versus 98 mL/cm H2O, P = 0.050), higher lung weight ratio (1.10 versus 0.96, P = 0.014), and higher linear intercept ratio (1.52 versus 0.93, P = 0.005) than the negative delta VT group. ConclusionsPositive delta VT appears as an ex vivo marker of ventilator-associated lung hyperinflation of smoker's lungs during EVLP.

Managing COPD with expiratory or inspiratory pressure load training based on a prolonged expiration pattern.

BackgroundExertional prolonged expiration should be identified as a therapeutic target in COPD. The efficacy of expiratory or inspiratory pressure load training (EPT/IPT) based on the degree of prolonged expiration was investigated.MethodsA total of 21 patients with COPD were divided into two groups according to the exertional change in the inspiratory duty cycle (TI/Ttot). For 12 weeks, patients whose exertional TI/Ttot decreased received EPT (EPT group, n=11, mean percentage forced expiratory volume in 1 s (%FEV1), 32.8%) and those whose exertional TI/Ttot increased received IPT (IPT group, n=10, mean %FEV1, 45.1%).ResultsThe therapeutic responses were as follows. In both groups, endurance time (EPT, +5.7 min, p<0.0001; IPT, +6.1 min, p=0.0004) on the constant work rate exercise test (WRET) and peak oxygen uptake increased (EPT, p=0.0028; IPT, p=0.0072). In the EPT group the following occurred: 1) soon after commencement of exercise with the constant WRET, the expiratory tidal volume (VTex) increased, reducing dyspnoea; 2) VTex and mean expiratory flow increased and then prolonged expiration (p=0.0001) improved at peak exercise with the incremental exercise test (ET); and 3) St. George's Respiratory Questionnaire total, activity and impact scores were improved. In the IPT group, on both the constant WRET and incremental ET, breathing frequency increased, which led to greater exercise performance with effort dyspnoea.ConclusionsThis study showed the benefits of EPT/IPT on exercise performance. If the choice of managing COPD with EPT/IPT is appropriate, inexpensive EPT/IPT may become widespread as home-based training.