Expiratory Tidal Volume Research Articles

A Comparison of Using Cuffed and Uncuffed Face Masks for Providing Manual Bag Ventilation in Elderly Patients with Obesity

Background: With the improvement of healthcare, the number of elderly individuals, including those with obesity, is increasing. The accumulation of various ventilation problems associated with the use of face masks in both these patient groups can pose a challenge even for an experienced anesthesiologist. The main aim of this study was to evaluate the ventilation of elderly patients with obesity using face masks, uncuffed or cuffed, and compare it with values obtained among patients with obesity who are not elderly. The secondary aim of the study was to demonstrate which of the two masks tested is better for elderly patients with android and gynoid obesity. Methods: This study was conducted at University Clinical Hospital No. 1 in Lodz among 108 patients with obesity, 50 elderly and 58 non-elderly. Patients’ BMIs ranged from 35.0 to 59.0. For the study, the uncuffed Intersurgical Eco Mask II and cuffed Ambu Ultra Seal face masks were used. Expiratory tidal volume and leakage obtained during the use of both types of masks were examined. The obtained data were analyzed using the Kolmogorov–Smirnov test and supplemented with Wilcoxon test values. Results: In elderly patients with obesity, especially those with gynoid obesity, the use of the Intersurgical Eco Mask II is associated with better ventilation parameters than the Ambu Ultra Seal mask. Only in the case of elderly patients with android obesity did the use of the Ambu Ultra Seal mask yield similar results to the Intersurgical Eco Mask II. Conclusions: Uncuffed face masks provide better ventilation parameters during manual bag ventilation in elderly patients with obesity.

Diagnosis of patients with chronic heart failure implementing wavelet transform and machine learning techniques

Chronic heart failure (CHF) is a significant public health concern due to its increasing prevalence, high number of hospital admissions, and associated mortality. Its prevalence is progressively increasing due to the aging of the population and the decrease in mortality from acute myocardial infarction, among other medical advancements. Consequently, the incidence of CHF predominantly affects older age groups, doubling its prevalence every decade, becoming one of the main causes of mortality in patients older than 65 years. The main objective of this study is to apply machine learning based techniques to determine the best models to classify patients with chronic heart failure through their respiratory pattern. These patterns have been characterized from time series such as inspiratory and expiratory times, breathing duration, and tidal volume obtained from the respiratory flow signal. Based on the behavior of the respiratory pattern, CHF patients were classified into patients with non-periodic breathing, with periodic breathing, and with Cheyene-Stokes respiration (CSR). Time-frequency and statistical techniques have been implemented to analyze these features, and then various classification methods have been applied to define the optimal model with the best accuracy rates. These models could help to better understand the evolution of this disease and in early diagnosis.

Outcomes of a Single Transverse Chest Roll for Prone Positioning Technique During Percutaneous Nephrolithotomy

ObjectiveTo compare anesthetic parameters using a novel prone single transverse chest roll technique (STR) to the standard thoraco-pelvic dual transverse roll technique (DTR). MethodsA retrospective review of 441 patients who underwent PCNL between 2018 to 2022 was performed. A total of 4 surgeons were included—surgeon 1 utilized the STR technique while surgeons 2, 3, and 4 used the DTR technique. Anesthetic parameters including end tidal CO2 (ETCO2), mean arterial pressure (MAP), peak airway pressure (Ppeak), plateau airway pressure (Pplat), positive end expiratory pressure (PEEP), oxygen saturation (SpO2), and tidal volume (TV) were compared between both groups at 0 (supine), 15, 30, and 60 minutes post-intubation intervals. Mixed effects regression models with interaction and pairwise comparisons were made between both groups (p<0.05). ResultsA total of 581 PCNLs were performed with 199 using STR and 382 using DTR. Surgery duration, ASA class, and age were similar amongst the STR and DTR groups. Estimated blood loss (59cc vs 83cc, p=0.007) and length of stay (77 hrs vs 163 hrs, p=<0.001) was significantly lower in the STR group. There was a significantly lower Ppeak, Pplat and TV in the STR compared to DTR group at 0, 15, 30, and 60 minutes (p<0.001). ConclusionUsage of a single transverse chest roll during prone PCNL appears to be a safe positioning method. STR patients had lower Ppeak and Pplat at all timepoints, which has been shown to be predictive of lower blood loss.

Characterisation of pulmonary air leak measurements using a mechanical ventilator in a bench setup

Prolonged air leakage (AL) following pulmonary resections leads to prolonged hospital stay and post-operative complications. Intra- and postoperative quantification of AL might be useful for improving treatment decisions, but these measurements have not been characterised. AL calculations based on inspiratory and expiratory tidal volumes were investigated in an Intensive Care Unit mechanical ventilator circuit (Servo-I). AL was also measured by a digital chest drainage system. This study shows that AL measurements increase in accuracy when corrected for baseline deviations (R: 0.904 > 0.997, p < 0.001). Bland-Altman analysis revealed a funnel-shape, indicative of a detection threshhold. Corrected measurements were most accurate when averaged over five breaths and AL was >500 mL/min, with an estimated mean systemic bias of 7.4% (95%-limits of agreement [LoA]: 1.1%-13.7%) at 500 mL/min air leak. Breath-by-breath analysis showed most accurate results at AL >20 mL/breath (R: 0.989–0.991, p < 0.001) at tidal volumes between 350–600 mL. The digital drain had a mean systemic bias of −11.1% (95%-LoA: −18.9% to −3.3%) with homogenous scatter in Bland-Altman analysis and a strong correlation to the control measurement over a large range (0–2000mL/min, R: 0.999, p < 0.001). This study indicates that the Servo-I can be used for air leak quantification in clinically relevant ranges (>500 mL/min), but is unsuited for small leak detection due to a detection threshold. Researchers and clinicians should be aware of varying accuracy and interoperability characteristics between AL measurement devices.

Influence of Head and Neck Position on Ventilation Using Three Different Supraglottic Airway Devices (I-Gel, Ambu Auragain, BaskaMask) in Anaesthetized and Paralyzed Patients: A Prospective Randomized Clinical Study

Background: Supraglottic airway devices play a crucial role in managing the airway during various surgical procedures conducted under general anesthesia. In this study, we evaluated the impact of different head and neck positions (extension, flexion, neutral, and right rotation) on ventilation while using I-gel, Ambu AuraGain, and Baska masks in anesthetized paralyzed patients. Methodology: A total of 114 patients were randomly allocated into Group I (n=38) using I-Gel, Group II (n=38) using Ambu AuraGain, and Group III (n=38) using Baska Mask. Clinical performance in terms of OLP (Oropharyngeal Leak Pressure) and anatomical position of the device was evaluated after insertion under general anaesthesia. Ventilation parameters including peak airway pressure, EtCO2 (End-tidal Carbon Dioxide), expiratory tidal volume and ventilation score were assessed at different head and neck positions using three supraglottic airway devices. Results : Maximum OLP was observed in Group II and minimum OLP was observed in Group I. In all three devices, OLP was maximum in the flexion position and minimum in the extension position. The Median Brimacombe score was 3 in all three groups at all head and neck positions except at maximum extension in Group I. Although peak airway pressure in Group II is significantly higher than the other two groups, ventilation is not impacted as evidenced by comparable ventilation score, EtCO2 and expiratory tidal volume in all patients of three groups at different head and neck positions. Conclusion : To conclude, Ambu Auragain has better anatomical seal at all head and neck positions as compared to I-gel and Baska Mask. However, despite differences in OLP, the ventilatory performances of the three devices were not significantly affected. Keywords: Ambu Auragain, Baska Mask, I-Gel, Supraglottic Airway Device, Head And Neck Position, Oropharyngeal Leak Pressure

Detection of dynamic lung hyperinflation using cardiopulmonary exercise testing and respiratory function in patients with stable cardiac disease: a multicenter, cross-sectional study.

Many patients with heart disease potentially have comorbid chronic obstructive pulmonary disease (COPD); however, there are not enough opportunities for screening, and the qualitative differentiation of shortness of breath (SOB) has not been well established. We investigated the detection rate of SOB based on a visual and qualitative dynamic lung hyperinflation (DLH) detection index during cardiopulmonary exercise testing (CPET) and assessed potential differences in respiratory function between groups. We recruited 534 patients with heart disease or patients who underwent simultaneous CPET and spirometry (369 males, 67.0 ± 12.9 years) to scrutinize physical functions. The difference between inspiratory and expiratory tidal volume was calculated (TV E-I) from the breath-by-breath data. Patients were grouped into convex (decreased TV E-I) and non-convex (unchanged or increased TV E-I) groups based on their TV E-I values after the start of exercise. Among the recruited patients, 129 (24.2%) were categorized in the convex group. There was no difference in clinical characteristics between the two groups. The Borg scale scores at the end of the CPET showed no difference. VE/VCO2 slope, its Y-intercept, and minimum VE/VCO2 showed no significant difference between the groups. In the convex group, FEV1.0/FVC was significantly lower compared to that in the non-convex group (69.4 ± 13.1 vs. 75.0 ± 9.0%). Moreover, significant correlations were observed between FEV1.0/FVC and Y-intercept (r=-0.343), as well as between the difference between minimum VE/VCO2 and VE/VCO2 slope (r=-0.478). The convex group showed decreased respiratory function, suggesting a potential airway obstruction during exercise. A combined assessment of the TV E-I and Y-intercept of the VE/VCO2 slope or the difference between the minimum VE/VCO2 and VE/VCO2 slopes could potentially detect COPD or airway obstruction.

The Use of Bi-Nasal Prongs for Delivery of Non-Invasive Ventilation to Foals.

Non-invasive ventilation (NIV) is a method of providing respiratory support without the need for airway intubation. The current study was undertaken to assess tolerance to bi-nasal prongs and NIV in healthy, standing, lightly sedated foals. Bi-nasal prongs were well tolerated by foals, remaining in place for the allocated five minutes in four of six unsedated foals and, subsequently, in five of six lightly sedated foals. All foals tolerated NIV through bi-nasal prongs, although increasing airway pressures were associated with increases in inspiratory volume, duration of inspiration and air leakage in most foals. These changes preceded discontinuation/intolerance of NIV on the basis of behaviour changes consistent with discomfort. Increased circuit leakage was associated with reduced return of expired air to the ventilator and increasing disparity between inspiratory and expiratory times and tidal volumes. The study results suggest that bi-nasal prongs might be suitable for NIV but that design or fitting requires further optimization and that behaviour and ventilator variables should be monitored to assess patient tolerance of the procedure.

Analyzing key elements of breathing patterns, deriving remaining variables, and identifying cutoff values in individuals with chronic respiratory disease and healthy subjects

BackgroundPulmonary physiology encompasses intricate breathing patterns (BPs), characterized by breathing frequency (Bf), volumes, and flows. The complexities intensify in the presence of interstitial lung disease (ILD) and chronic obstructive pulmonary disease (COPD), especially during exercise. This study seeks to identify pivotal factors driving changes among these variables and establish cutoff values, comparing their efficacy in differentiating BPs to traditional methods, specifically a breathing reserve (BR) of 30% and a Bf of 50 bpm. MethodsScreening 267 subjects revealed 23 with ILD, 126 with COPD, 33 healthy individuals, and the exclusion of 85 subjects. Lung function tests and ramp-pattern cardiopulmonary exercise testing (CPET) were conducted, identifying crucial BP elements. Changes were compared between groups at peak exercise. The area under the receiver operating characteristic curve (AUC) analysis determined cutoff values. ResultsInspiratory time (TI) remained constant at peak exercise for all subjects (two-group comparisons, all p=NS). Given known differences in expiratory time (TE) and tidal volume (VT) among ILD, COPD, and healthy states, constant TI could infer patterns for Bf, total breathing cycle time (TTOT=60/Bf), I:E ratio, inspiratory duty cycle (IDC, TI/TTOT), rapid shallow breathing index (Bf/VT), tidal inspiratory and expiratory flows (VT/TI and VT/TE), and minute ventilation (V̇E=Bf×VT) across conditions. These inferences aligned with measurements, with potential type II errors causing inconsistencies. RSBI of 23 bpm/L and VT/TI of 104 L/min may differentiate ILD from control, while V̇E of 54 L/min, BR of 30%, and VT/TE of 108 may differentiate COPD from control. BR of 21%, TE of 0.99 s, and IDC of .45 may differentiate ILD from COPD. The algorithm outperformed traditional methods (AUC 0.84–0.91 versus 0.59–0.90). ConclusionThe quasi-fixed TI, in conjunction with TE and VT, proves effective in inferring time-related variables of BPs. The findings have the potential to significantly enhance medical education in interpreting cardiopulmonary exercise testing. Moreover, the study introduces a novel algorithm for distinguishing BPs among individuals with ILD, COPD, and those who are healthy.

Comprehensive study of mechanical power in controlled mechanical ventilation: Prevalence of elevated mechanical power and component analysis

ObjectiveTo determine the prevalence of elevated mechanical power (MP) values (>17J/min) used in routine clinical practice. DesignObservational, descriptive, cross-sectional, analytical, multicenter, international study conducted on November 21, 2019, from 8:00 AM to 3:00 PM. NCT03936231. SettingOne hundred thirty-three Critical Care Units. PatientsPatients receiving invasive mechanical ventilation for any cause. InterventionsNone. Main variables of interestMechanical power. ResultsA population of 372 patients was analyzed. PM was significantly higher in patients under pressure-controlled ventilation (PC) compared to volume-controlled ventilation (VC) (19.20±8.44J/min vs. 16.01±6.88J/min; p<0.001), but the percentage of patients with PM>17J/min was not different (41% vs. 35%, respectively; p=0.382). The best models according to AICcw expressing PM for patients in VC are described as follows: Surrogate Strain (Driving Pressure) + PEEP+Surrogate Strain Rate (PEEP/Flow Ratio) + Respiratory Rate. For patients in PC, it is defined as: Surrogate Strain (Expiratory Tidal Volume/PEEP) + PEEP+Surrogate Strain Rate (Surrogate Strain/Ti) + Respiratory Rate+Expiratory Tidal Volume+Ti. ConclusionsA substantial proportion of mechanically ventilated patients may be at risk of experiencing elevated levels of mechanical power. Despite observed differences in mechanical power values between VC and PC ventilation, they did not result in a significant disparity in the prevalence of high mechanical power values.

Comparison of Dynamic and Static Compliance in Two Ventilation Methods with Tidal Volume of 6 and 10 ml/kg: Randomized Clinical Trial.

Pulmonary compliance is an important lung factor and is affected by tidal volume. In this study, static and dynamic compliance with tidal volumes of 6 and 10 ml/kg have been evaluated in patients undergoing abdominal cancer surgery. This randomized clinical trial was conducted on 50 patients who were candidate for abdominal cancer surgery. This study was done in patients aged 20-65 years without chronic diseases. After induction of anesthesia, the first group was ventilated with a tidal volume of 10 ml/kg and 8 breaths/minute, and also the second group was ventilated with a tidal volume of 6 mL/kg and 14 breaths/minute. From the beginning and every 15 minutes, expiratory tidal volume, peak and plateau airway pressure, heart rate and blood pressure were measured for two hours. The data was analyzed with SPSS v.20 and P < 0.05 was meaningful. There was no significant difference between the two groups for demographic characteristics. There was no significant difference between the two groups in the dynamic and static compliance of the patients during the study. However, the static compliance decreased in the 6 ml/kg group and increased in the 10 ml/kg group, but the difference was not statistically significant (P = 0.32). The peak, plateau pressure and hemodynamic parameters were the same in the two groups. In general, the static and dynamic compliance was not significantly different in the two groups despite a slight decrease in the 6 ml/kg group and a slight increase in the 10 ml/kg group.

Efficiency of face mask ventilation before and after neuromuscular blockade: A randomised, double-blind controlled study.

The traditional practice of administrating neuromuscular blocking drugs (NMBDs) after checking face mask ventilation is challenged repeatedly. This study compared the efficiency of face mask ventilation before and after administrating an NMBD in a patient with a normal airway. The secondary outcome measured was the grade of mask ventilation and tracheal intubating conditions. After ethical approval, patients (n = 120) in the age group of 18-65 years scheduled for elective surgery under general anaesthesia were randomly assigned into two groups. Group 1 received an NMBD before checking face mask ventilation. Group 2 received an NMBD after checking face mask ventilation. Lungs were ventilated for 180 s, during which expiratory tidal volume (Vte) was recorded as the primary outcome. Hans's grading for face mask ventilation was used to grade mask ventilation. The ease of intubation was assessed based on intubating conditions (ease of laryngoscopy, vocal cord movement, and limb movement). SPSS 20.0 software was used for statistical analysis. For a total of 180 seconds of mask ventilation, the mean (standard deviation) Vte measured after apnoea was significantly higher in Group 1 versus Group 2 [471.9 (63.3) vs 434.8 (77.0) mL/breath, P = 0.004]. The intubating condition was either excellent or good in all patients. The administration of NMBDs resulted in a larger mask Vte and shorter intubation time.

Effects of Diaphragmatic Breathing in Sickle Cell Disease Patients: Preliminary Data

Introduction: Sickle cell disease (SCD) can be defined as an autosomal recessive disease, characterized by hemolytic anemia, progressive lesions in most organs and vaso-occlusive crises. Affected individuals suffer from severe pain due to vaso-occlusion and ischemic damage. Acute and chronic pulmonary complications including acute thoracic syndrome, pulmonary hypertension, thromboembolism, sleep-disordered breathing and asthma are among the leading causes of morbidity and mortality of SCD individuals. Dyspnea may be present due to pulmonary involvement, exercise intolerance, as well as a feature of pulmonary complications or due to the complications inherent to SCD. The practice of diaphragmatic breathing (DB) has been shown to improve exercise tolerance, reduce dyspnea and increase inspiratory muscle strength in several diseases, especially asthma and chronic obstructive pulmonary disease. However, the effects of this breathing exercise are not yet known in patients with SCD. Thus, the aim of this study was to evaluate the effects of BD in patients with SCD. Methods: The study was approved by the UNICAMP ethics committee and all the patients who agreed to participate signed a written informed consent form. Participants were randomly divided into a control group (CG) and an intervention group (IG). The IG was instructed to do 3 sets of 20 repetitions per day of DB at home, 5 times a week. They were instructed to write down the date and time of DB, as well as justify any reason that prevented them from carrying out the training at some point. Patients in both groups were contacted weekly via the smartphone messaging application (app). In the case of IG patients, this contact aimed to reinforce the importance of continuing the intervention protocol. For the CG participants, the weekly contact was important in order avoid a bias of the GI participants alone receiving continuous attention from the researchers. In addition, once a week, IG participants had to record and send a video via the smartphone messaging app showing how they were doing the exercise. The video was analyzed and the patient received feedback, also via messaging app, from the researchers with compliments or suggestions for corrections regarding the practice of DB. Thus, there was constant monitoring of the implementation of the intervention protocol seeking to maintain patient adherence to the training protocol. The CG did not perform any breathing exercises during the study. The effects of DB on SCD patients were evaluated twice, the initial evaluation (IE) and final evaluation (FE), performed with a 12-week interval and consisted of the application of the Modified Medical Research Council Scale (mMRC), assessment of the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), volumetric capnography (VCap) and 6-minute walk test (6MWT). Comparison between groups was performed using the Mann-Whitney and Fisher's exact tests. Within-group comparisons of BD effects were performed using Wilcoxon's Sign Rank Test. The comparison between groups was performed with the Mann-Whitney Test with Bonferroni correction. Results: 19 patients completed the 12 weeks between IE and FE. There were no significant differences between CG (n=9) and IG (n=10) based on age (p=0.1619), sex (p=0.0698), body mass index (p=0.5490) or severity of genotype (n=13 HbSS, 4 HbSC, 1 HbSβ0 and 1 HbSβ +) with p=0.9879. At the end of the DB protocol, in the within-group comparations, the IG presented significant changes in MIP (p=0.0117) and among the variables measured by VCap, such as inspiratory tidal volume (p=0.0371), expiratory tidal volume (p=0.0371), Tobin index (p=0.0488) and oxygen saturation (p=0.0488). No significant alterations were observed in the other variables evaluated in between-group comparisons. The CG showed no significant change in any of the comparisons. Conclusions: DB is an exercise that can be easily applied to outpatients with SCD, allowing for an improvement in inspiratory muscle strength, VCap and favoring blood oxygenation in these individuals. Funding: FAPESP 2017/21801-2; CNPq grants #303405/2018-0; #405918/2022-4 - Instituto Nacional de Ciência e Tecnologia do Sangue (INCT do Sangue).

Lung function in preterm infants at 3 months corrected age after neonatal LC-PUFA supplementation.

To test the hypothesis that long-chain polyunsaturated fatty acid (LC-PUFA) supplementation improves lung function at 3 months corrected age (CA) compared with standard treatment in very preterm infants. We also aimed to investigate the association between bronchopulmonary dysplasia (BPD), longitudinal growth, and lung function at 3 months CA. A secondary analysis from the ImNuT trial, in which 121 infants with gestational age <29 weeks were randomized to a daily supplement with arachidonic acid (ARA) and docosahexaenoic acid (DHA) (ARA:DHA group) or MCT-oil (control group) from birth up to 36 weeks postmenstrual age (PMA). Lung function was assessed at 3 months CA by tidal flow volume loops and the outcomes were the ratio of time to peak tidal expiratory flow to expiratory time (tPTEF /tE ) and tidal volume (VT ) per body weight (mL/kg). Thirty-nine infants in the ARA:DHA group versus 51 in the control group had a successful lung function test. There was no mean difference (MD) in tPTEF /tE ratio (MD: 0.01, 95% confidence interval [CI]: -0.04 to 0.05; p = .77) or VT (MD: 0.09 mL/kg, 95% CI: -0.79 to 0.62; p = .81) between the study groups. The multivariable regression model showed that BPD was associated with tPTEF /tE ratio ≤ 0.25 (p = .03) and that an increase in z score for length after 36 weeks PMA correlated positively with VT (mL/kg) (p = .03). Neonatal LC-PUFA supplementation did not improve lung function at 3 months CA in very preterm infants. BPD was independently associated with reduced lung function, while improved linear growth correlated with higher tidal volumes.

Abstract 321: Manual vs Automated Ventilation During Automated Head-Up Cardiopulmonary Resuscitation in a Porcine Model

Background: The efficacy of mechanical ventilation during CPR with the combination of active compression-decompression, an impedance threshold device, and head-up positioning, collectively termed automated head-up (AHUP)-CPR, is unknown. Hypothesis: Hemodynamic and ventilatory parameters will be similar with manual bag ventilation (MBV) versus automated bag ventilation (ABV) during AHUP-CPR in a porcine model of cardiac arrest. Aim: Assess the proof-of-concept that ABV is safe and effective during AHUP-CPR. Methods: Nine male and female swine (~40 kg) were anesthetized and ventilated. VF was induced and left untreated for 8 min. AHUP-CPR was performed at 105 compressions/min for 7 min using MBV, followed by 6 min using an automated mechanical bag compressor to deliver 10ml/kg of tidal volume (TV) over 1 sec at 10 breaths/min. Pigs were randomized during ABV to a synchronized (Sync) breath delivered at the start of decompression or an asynchronous (Async) breath. Cerebral perfusion pressure, coronary perfusion pressure, end-tidal CO2, intracranial pressure, esophageal intrathoracic pressure, peak airway pressure (PAP), inspiratory and expiratory TVs as well as arterial blood gases were continuously measured. Values (mean ± SD) were compared by paired and unpaired student’s t-tests with a Bonferroni correction. Results: Parameters during the last minute of MBV and ABV are summarized in the table. No significant differences were observed in hemodynamic and ventilatory parameters, except for PAP and pO2 values which were significantly lower with MBV. No significant differences were also observed between the Sync and Async ABV modes. Conclusion: Manual and mechanical ventilation resulted in overall similar physiological effects. The clinical relevance of the observed significant differences in PAP and pO2 is unclear. Additional studies are warranted to further assess the safety and effectiveness of mechanical ventilation during AHUP-CPR.

Comparison of ventilatory and oxygen consumption measurements of yearling Thoroughbred colts and fillies exercising unridden on an all-weather track

Sex effects on ventilatory and oxygen consumption (V̇O2) measurements during exercise have been identified in humans. This study’s aim was to evaluate the hypothesis that there are sex effects on ventilatory and V̇O2 measurements in exercising, untrained yearling Thoroughbreds (Tb). Forty-one Tbs (16 colts, 25 fillies; 19.8 ± 1.4 months old) were recruited. Physiological, ventilatory and exercise data were gathered from horses exercising unridden at high intensity on an all-weather track from a global positioning-heart rate unit and a portable ergospirometry system. Data were analysed with an unpaired Student’s t-test and the Benjamini-Hochberg correction for multiple testing (P ≤ 0.05 significant). Mean bodyweight (BW, P = 0.002) and wither height (P = 0.04) were greater for colts than fillies. There were no differences in physiological and exercise data and absolute peak V̇O2 between groups. However, fillies had a higher mass specific peak V̇O2 (P = 0.03) than colts (121.5 ± 21.6 mL/kg.min vs. 111.9 ± 27.4 mL/kg.min). The peak breathing frequency was greater for fillies (P < 0.001) while the peak inspiratory (P < 0.001) and expiratory air flow (P < 0.001), peak expiratory tidal volume (VTE; P < 0.001) and peak minute ventilation (V̇E; P = 0.01) were greater for colts; there were no differences for peak VTE and V̇E when adjusted for BW. Differences in BW explain the differences in mass specific peak V̇O2 between groups. Given their morphological differences, it is likely that lung volumes and airway diameters are smaller for fillies, resulting in greater resistance and lower air flows and volumes. Further research is required to investigate the ventilatory differences and how they may change with maturation and impact performance.

Laryngeal widening and adequate ventilation by expiratory pressure load training improve aerobic capacity in COPD: a randomised controlled trial

RationaleDespite strategies acting on peripheral airway obstruction in chronic obstructive pulmonary disease (COPD), exercise intolerance remains inadequately improved. We hypothesised that laryngeal narrowing is a potential treatment target of expiratory...

The effect intraoperative positive end expiratory pressure and tidal volume on postoperative acute kidney injury after orthopedic surgery.

To test whether higher intraoperative PEEP levels and/or higher TV levels are associated with higher incidence of postoperative AKI within the first postoperative week, in adult patients having orthopedic surgeries under general anesthesia. We conducted a sub analysis of a non-randomized alternating intervention cross over study performed in patients undergoing orthopedic surgery under general anesthesia at Cleveland Clinic, Cleveland, OH. We included four different combinations of PEEP (5 or 8 cm H2 O) and TV (6 or 10 mL/kg of PBW) that alternated each week in the six orthopedic operating rooms. Our primary outcome was postoperative AKI defined by the KDIGO criteria with baseline creatinine as the closest preoperative value to the time of surgery obtained within 30 days and postoperative value as the highest creatinine value within 7 days after surgery. Secondary outcome was the maximum postoperative in-hospital creatinine level within seven postoperative days. A total of 1933 patients were included in the analysis. The incidence of AKI was 6.8% in the study population and similar in high TV versus low TV group and high PEEP versus low PEEP group. Neither TV nor PEEP significantly impacted AKI incidence. The estimated odds ratio of AKI comparing TV = 6 mL/kg to TV = 10 mL/kg was 0.96 (97.5% CI: 0.63, 1.46; p = .811); while the estimated odds ratio of AKI comparing PEEP = 5cm H2 O to PEEP = 8cm H2 O was 0.92 (97.5% CI: 0.60, 1.39; p = .623). No interaction was found between TV and PEEP on AKI. Additionally, neither TV nor PEEP had a significant effect on the seven postoperative day creatinine levels. Higher levels of PEEP or TV during mechanical ventilation in adult patients undergoing orthopedic surgeries under general anesthesia do not increase the odds of developing postoperative AKI within the narrow limits studied.

Comparison of volume-controlled and pressure-controlled ventilation during laryngeal mask airway anesthesia in cataract surgery

Introduction: Most patients undergoing eye surgery are elderly adults with underlying cardiovascular diseases. One of the complications during recovery is gastric insufflation, which can cause detrimental effects on cardiovascular patients. The present study compares two methods of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Methods: The study enrolled 81 patients undergoing cataract surgery (41 in the PCV group and 40 in the VCV group). According to the American Society of Anaesthesiologists (ASA) classes I and II received general anaesthesia and laryngeal mask airway (LMA) ventilation using VCV or PCV. Maximum pressure (Ppeak), dynamic compliance, expiratory tidal volume, Spo2, non-invasive blood pressure, heart rate, and pain in the epigastrium and umbilical region were monitored at intervals of 1, 5, 10, and 20 minutes after the initiation of anaesthesia and the results of two groups were compared. Results: The means of Ppeak and tidal volume in the PCV group as well as the means of dynamic compliance and end-tidal carbon dioxide (EtCO2) in the VCV group were significantly high. The mean diastolic blood pressure was significantly different between two groups at 20th minute. There were no significant differences in heart rate, mean systolic blood pressure, arterial oxygen saturation, or abdominal pain between two study groups. Conclusion: VCV had a lower Ppeak and a higher dynamic compliance, but PCV had a larger tidal volume and lower EtCO2. There were no differences in terms of abdominal and umbilicus pain, as well as hemodynamic parameters, between two groups.

A primer for the student joining the adult cardiac surgery service tomorrow: Primer 1 of 7

A primer for the student joining the adult cardiac surgery service tomorrow: Primer 1 of 7

Laryngeal Ultrasonography and Percent Leak Volume in Predicting Post-Extubation Stridor in The Pediatric Intensive Care Unit Patients

Background: Endotracheal tube intubation can be associated with laryngeal edema, which may present as post-extubation stridor (PES). PES may prolong length of stay in pediatric intensive care unit, particularly if reintubation was necessary. Objective: To evaluate the efficacy of laryngeal ultrasonography and percent leak volume (PLV) in predicting PES in pediatric patients. Materials and Methods: A prospective study of 43 pediatric patients admitted to pediatric intensive care unit was conducted. Laryngeal ultrasonography was performed to measure air column width (ACW) within 24 hours after intubation. Within four hours before extubation, laryngeal ultrasonography was repeated. Air column width ratio (ACWR) was calculated by ACW before extubation divided by ACW after intubation. PLV was calculated by the difference between inspiratory and expiratory tidal volume divided by inspiratory tidal volume. Both of ACWR and PLV were analyzed to determine the optimal cut-off value for predicting PES. Results: Twenty-two patients (51%), developed PES. Receiver operating characteristics curve (ROC) analysis showed that ACWR at cut-off point ≤0.94 had a sensitivity of 72.7%, specificity of 61.9%, positive predictive value (PPV) of 66.7%, and accuracy of 67.4% in predicting PES. A cut-off point of PLV of less than 9.74% had 59.1% sensitivity, 57.1% specificity, 59.1% PPV, and 58.1% accuracy in predicting PES. ACWR and PLV had an area under the ROC curve (AUC) of 0.722 (p=0.013, 95% CI 0.56 to 0.87) and 0.602 (p=0.253, 95% CI 0.43 to 0.77), respectively. Conclusion: ACWR measured by laryngeal ultrasonography of 0.94 or less may be helpful in predicting PES. ACWR is more accurate than PLV in predicting PES. Keywords: Laryngeal ultrasonography; Percent leak volume; Post-extubation stridor