Total Ventilation Research Articles

Quantifying particulate matter emission rates from naturally ventilated dairy buildings by considering roof opening contributions

Roof openings are typically fitted to naturally ventilated dairy building (NVDB) for better ventilation but their impact on air pollutant emission calculations has not been fully considered. Particulate matter (PM) emission rate (ER) for NVDB rely on the total ventilation rate (VR), outdoor PM concentration and average indoor PM concentration sampled either under the roof (Roof Sampling) or in the cubicle area (Cubicle Sampling), which may show large deviations due to its spatiotemporal variation of PM concentrations and complex airflow patterns. This study utilised a novel ER calculation method (Joint Sampling) that computes the respective emission from the roof and sidewall openings by matching each outlet's VR and PM concentration. By year-round field measurements of PM2.5 and the total suspended particulates (TSP), results showed that annual average ERs of PM2.5 and TSP were 10.8 mg h−1 cow−1 and 45.7 mg h−1 cow−1 for Roof Sampling, 12.7 mg h−1 cow−1 and 40.7 mg h−1 cow−1 for Cubicle Sampling, and 11.7 mg h−1 cow−1 and 45.9 mg h−1 cow−1 for Joint Sampling. Considering the Joint Sampling results were relatively true, Roof Sampling exhibited a maximum underestimate of PM2.5 emissions of 20.8% when sidewall curtains were fully opened, whilst Cubicle Sampling demonstrated a maximum overestimate of TSP of 10.2% when the aperture was closed. Using Joint Sampling, the roof opening contributed 39.3% and 24.4% of the annual PM2.5 and TSP emissions. When sidewall openings are partially or fully closed, the Joint Sampling calculation is preferable to estimate the ER of PM.

Human serum albumin: prediction model and reference values for preterm and term neonates.

Human serum albumin (HSA) concentrations may alter HSA-bound drug distribution. This study aims to describe longitudinal real-world HSA trends, and to develop a prediction model for HSA concentrations using a large neonatal cohort. Patients admitted to the neonatal intensive care unit of the University Hospitals Leuven (postnatal age (PNA) ≤28days) were retrospectively included. Using linear mixed models, covariate effects on HSA were explored. A multivariable prediction model was developed (backward model selection procedure, 1% significance level). In total, 848 neonates were included [median(interquartile range) gestational age (GA) 35(32-38)weeks, birth weight (BW) 2400(1640-3130)grams]. Median HSA concentration was 32.3(28.7-35.6)g/L. Longitudinal analyses demonstrated increasing HSA concentrations with PNA and GA for most GA groups. Univariable analyses revealed significant associations of HSA with PNA, GA, BW, current weight, total and direct bilirubin, total plasma proteins, respiratory support, mechanical ventilation, sepsis, ibuprofen use, and C-reactive protein (p-values < 0.05). A high-performance (R2 = 76.3%) multivariable HSA prediction model was developed, and PNA- and GA-dependent HSA centiles were provided. Population-specific HSA centiles and an accurate neonatal HSA prediction model were developed, incorporating both maturational and non-maturational covariates. These results can enhance future clinical care and pharmacokinetic analyses to improve pharmacotherapy of HSA-bound drugs in neonates, respectively. To improve future pharmacokinetic modeling initiatives, a high-performance human serum albumin (HSA) prediction model was developed for (pre)term neonates, using a large, single-center cohort of real-world data. This prediction model integrates both maturational and non-maturational covariates, resulting in accurate HSA predictions in neonates. Additionally, HSA centiles based on postnatal and gestational age were developed, which can be easily applied in clinical practice when interpreting HSA concentrations of neonates. In general, unbound drug fractions are higher in neonates compared to older populations. To improve pharmacotherapy of HSA-bound drugs in neonates, the obtained results can be integrated in future pharmacokinetic-pharmacodynamic analyses.

Perioperative assessment of diaphragmatic dysfunction in cardiac surgery patients and its effect on outcome; a prospective observational study

Objectives: While the assessment of the diaphragm in different clinical scenarios is quite frequent, there remains a scarcity of studies focused on assessing diaphragm dysfunction using ultrasound in cardiac surgery patients. We investigated the impact of cardiopulmonary bypass (CPB) surgery on diaphragm function and evaluated its effects on mechanical ventilation. Methodology: A prospective cohort study, on 100 consecutive adult cardiac surgery patients, was conducted at National Heart Institute. Diaphragmatic displacement (DD) or excursion and diaphragmatic thickening fraction (DTF) were measured using motion-mode ultrasound during quite normal breathing pre-operatively (the day before surgery) and post-operatively on mechanical ventilation, while the patient was fully conscious and spontaneously breathing on continuous positive airway pressure (CPAP) mode + pressure support 10 cmH2O. Then, the results were correlated to CBP time and important patient outcomes. Results: Post-operative DD was significantly less as compared to the pre-operative reading; (1.39 ± 0.42 cm vs. 2.3 ± 0.52 cm; P &lt; 0.001), as was DTF (23% ± 10% vs. 40% ± 13%; P &lt; 0.001). The incidence of diaphragmatic dysfunction post-cardiac surgery was 17% by the definition of DD &lt; 1 cm, and 49% by the definition of DTF ≤ 20%. DD was positively correlated with CBP time, as well as total ventilation time and ICU stay, indicating a negative impact on overall patient outcomes. Conclusion: The results suggest that diaphragmatic dysfunction is positively correlated with CPB time, total ventilation time and ICU stay, underscoring the importance of monitoring diaphragmatic function in post-operative patients, who are difficult to wean from mechanical ventilation with apparently normal chest X-ray, particularly those with prolonged CPB time. Keywords: cardiac surgery; cardiopulmonary bypass; diaphragm dysfunction; diaphragmatic displacement; diaphragm ultrasound; mechanical ventilation. Citation: Omara ISM, Nagi HK, Mohamed KAA, Abd El Haq HH, Awdallah FF. Perioperative assessment of diaphragmatic dysfunction in cardiac surgery patients and its effect on outcome; a prospective observational study. Anaesth. pain intensive care 2024;28(5):816−823; DOI: 10.35975/apic.v28i5.2555 Received: June 28, 2024; Reviewed: September 04, 2024; Accepted: September 06, 2024

Impact of Humidification Modality on Incidence of Endotracheal Tube Occlusion in COVID-19 Patients.

Background: Endotracheal tube (ETT) occlusion is reported at a higher frequency among coronavirus disease-2019 (COVID-19) patients. Prior to the COVID-19 pandemic, literature examining patient and ventilator characteristics, including humidification, as etiologies of ETT occlusion yielded mixed results. Our study examines the relationship of humidification modality with ETT occlusion in COVID-19 patients undergoing invasive mechanical ventilation (IMV). Methods: We conducted a retrospective chart review of COVID-19 patients requiring IMV at a tertiary care center in New York from April 2020 to April 2021. Teleflex Neptune heated wire heated humidification (HH) and hygroscopic Intersurgical FiltaTherm and Sunmed Ballard 1500 heat and moisture exchangers (HME) were used. Episodes of ETT occlusion were recorded. Univariate and multivariable logistic regression models were used to investigate the relationship between humidification modality and the occurrence of ETT occlusion. Findings: A total of 201 eligible patients were identified. Teleflex HH was utilized in 50.2% of the population and the others Intersurgical and Sunmed HME devices. Median age was 62 years and 78.6% of patients had at least one medical comorbidity. Precisely, 24% of patients experienced an ETT occlusion after a median of 12 days. The HME group was younger (58.5 vs 64 years), predominantly male (75% vs 59.4%), and experienced more total ventilator days than the HH group (24 vs 12). Those using the studied HME devices had significantly higher odds of ETT occlusion (OR 4.4, 95% CI 1.8-10.6, P = .0011). Three patients (6.1%) experienced cardiac arrest as a consequence of their occlusion. There were no deaths directly attributed to ETT occlusion. Conclusions: The studied HME devices were significantly associated with higher odds of ETT occlusion in COVID-19 patients requiring invasive mechanical ventilation. These events are not without significant clinical consequences. Prolonged use of under-performing HME devices remains suspect in the occurrence of ETT occlusions.

Single institution review of operative management of giant omphalocele

PurposeOperative management of giant omphalocele that cannot be closed primarily varies based on several factors, and there is little data to guide choice of operative approach and how this impacts long-term outcomes. We aimed to characterize whether surgical approach – staged closure during the neonatal period, or delayed closure – affects outcomes. MethodsWe conducted a retrospective review of children treated for giant omphalocele who did not undergo primary closure at Children's Hospital Colorado from 2010–2022. We included patients with giant omphalocele who underwent treatment at the study site. Data collected included patient characteristics, clinical course, and outcomes. Comparisons were made based on type of closure, delayed versus staged. ResultsWe identified 24 patients; 6 delayed and 16 staged. 2 patients died prior to closure. Delayed and staged groups did not differ regarding demographics. Infants undergoing staged repair tended to have more total hospital and total ventilator days, and more post-closure ventral hernia requiring repair; short-term outcomes were otherwise comparable. There was no difference between groups in long-term outcomes, including neurodevelopmental milestones and mortality. ConclusionsLong term outcomes are equivalent between staged repair and delayed repair of giant omphalocele. However, staged repair may be associated with more ventilator days, total hospital days and higher risk of ventral hernia.

Effects of Dexmedetomidine in Improving Oxygenation and Reducing Pulmonary Shunt in High-Risk Pediatric Patients Undergoing One-Lung Ventilation for Thoracic Surgery: A Double-Blind Randomized Controlled Trial.

Background and objectives Pediatric thoracic surgery has unique considerations due to the immaturity of the respiratory system anatomically and physiologically, which presents technical and pharmacological considerations, including the very common technique of one-lung ventilation (OLV), which causes serious complications in children. Therefore, we investigated the effects of dexmedetomidine on oxygenation and pulmonary shunt fraction (Qs/Qt) in high-risk pediatric patients undergoing OLV for thoracic surgery. This randomized controlled trial aimed to investigate dexmedetomidine's effect on the partial pressure of arterial oxygen (PaO2) and pulmonary shunt fraction (Qs/Qt). Methods A total of 63 children underwent thoracic surgery with OLV and were divided into two groups. The dexmedetomidine group (group Dex, n = 32) received dexmedetomidine (0.4 μg/kg/hour), and the placebo group (group placebo, n = 31) received normal saline. Two arterial and central venous blood samples were taken for arterial and venous blood gas analysis at four time points: T1 (10 minutes after mechanical ventilation of total lung ventilation), T2 (10 minutes after OLV), T3 (60 minutes after OLV), and T4 (20 minutes after the end of OLV). At these intervals, the following parameters were measured: PaO2, Qs/Qt, mean arterial pressure (MAP), heart rate (HR), and peak inspiratory pressure (PIP). Results The two groups had no significant differences in FEV1/FVC and baseline pulmonary shunt fraction (Qs/Qt). Dexmedetomidine significantly improved PaO2 compared with placebo during OLV (T2 and T3). There was a significant decrease in Qs/Qt compared with placebo during OLV (T2, T3, and T4). There was a decrease in PIP compared with placebo during OLV (T2 and T3). No statistically significant differences in MAP or HR were observed between the groups. Conclusion Infusion of dexmedetomidine during OLV in high-risk pediatric thoracic surgery reduces shunt and pulmonary shunt fraction Qs/Qt, improves PaO2 and body oxygenation, reduces PIP and pressure load, and maintains hemodynamic stability (MAP, HR).

Effect of body position during weaning from total liquid ventilation in piglets

ObjectiveTo determine if change in body position improves oxygen requirements and respiratory mechanics during the transition from total liquid ventilation (TLV) to gas ventilation. MethodsFourteen piglets underwent TLV, followed by a 2-hour weaning period under conventional gas ventilation. Subjects were randomized to the experimental group (Rotating – R), that was in prone position between the 10th and 30th minute of weaning, or to the static control group (Supine – S). ResultsOxygenation index was lower in the R group at 30 minutes in prone position than that in the S group (1.9 [1.6; 2.8] vs 3.5 [3.1; 5.1], p = 0.001). This difference disappeared when subjects resumed the supine position (4.2 [3.8; 4.7] and 4.7 [3.8; 5.4], p = 0.4, for the R and S groups, respectively). The change in body position did not affect respiratory system compliance or inspiratory capacity. ConclusionProne position improved oxygenation during weaning from TLV. The effect disappeared once piglets returned to the supine position.

Impact of work pace on cardiorespiratory outcomes, perceived effort and carried load in industrial workers: a randomised cross-over trial

ObjectivesThis study investigates the impact of different work paces on cardiorespiratory outcomes, perceived effort and carried load (CL) in industrial workers.MethodsA randomised cross-over trial was conducted at a mid-sized steel...

Preload responsiveness–guided fluid removal in mechanically ventilated patients with fluid overload: A comprehensive clinical–physiological study

This study investigated fluid removal strategies for critically ill patients with fluid overload on mechanical ventilation. Traditionally, a negative fluid balance (FB) is aimed for. However, this approach can have drawbacks. Here, we compared a new approach, namely removing fluids until patients become fluid responsive (FR) to the traditional empiric negative balance approach.Twelve patients were placed in each group (n = 24). FR assessment was performed using passive leg raising (PLR). Both groups maintained stable blood pressure and heart function during fluid management. Notably, the FR group weaned from the ventilator significantly faster than negative FB group (both for a spontaneous breathing trial (14 h vs. 36 h, p = 0.031) and extubation (26 h vs. 57 h, p = 0.007); the difference in total ventilator time wasn't statistically significant (49 h vs. 62 h, p = 0.065). Additionally, FR group avoided metabolic problems like secondary alkalosis and potential hypokalemia seen in the negative FB group.FR-guided fluid-removal in fluid overloaded mechanically ventilated patients was a feasible, safe, and maybe superior strategy in facilitating weaning and disconnection from mechanical ventilation than negative FB-driven fluid removal. FR is a safe endpoint for optimizing cardiac function and preventing adverse consequences during fluid removal.

Ultrafast Cooling With Total Liquid Ventilation Mitigates Early Inflammatory Response and Offers Neuroprotection in aPorcine Model of Cardiac Arrest.

Brain injury is one of the most serious complications after cardiac arrest (CA). To prevent this phenomenon, rapid cooling with total liquid ventilation (TLV) has been proposed in small animal models of CA (rabbits and piglets). Here, we aimed to determine whether hypothermic TLV can also offer neuroprotection and mitigate cerebral inflammatory response in large animals. Anesthetized pigs were subjected to 14 minutes of ventricular fibrillation followed by cardiopulmonary resuscitation. After return of spontaneous circulation, animals were randomly subjected to normothermia (control group, n=8) or ultrafast cooling with TLV (TLV group, n=8). In the latter group, TLV was initiated within a window of 15 minutes after return of spontaneous circulation and allowed to reduce tympanic, esophageal, and bladder temperature to the 32 to 34 °C range within 30 minutes. After 45 minutes of TLV, gas ventilation was resumed, and hypothermia was maintained externally until 3 hours after CA, before rewarming using heat pads (0.5 °C-1 °C/h). After an additional period of progressive rewarming for 3 hours, animals were euthanized for brain withdrawal and histological analysis. At the end of the follow-up (ie, 6 hours after CA), histology showed reduced brain injury as witnessed by the reduced number of Fluroro-Jade C-positive cerebral degenerating neurons in TLV versus control. IL (interleukin)-1ra and IL-8 levels were also significantly reduced in the cerebrospinal fluid in TLV versus control along with cerebral infiltration by CD3+ cells. Conversely, circulating levels of cytokines were not different among groups, suggesting a discrepancy between local and systemic inflammatory levels. Ultrafast cooling with TLV mitigates neuroinflammation and attenuates acute brain lesions in the early phase following resuscitation in large animals subjected to CA.

Is Ventilator-associated Event Algorithm Ideal for Surveillance? – Experience from a Neurosurgery Intensive Care Unit in Kerala

ABSTRACT Background: The ventilator-associated event (VAE) surveillance algorithm was brought in to replace the clinical ventilator-associated pneumonia (VAP) surveillance by NHSN in January 2013. This study intends to find the correlation of these surveillance criteria with the clinical VAP rates in a neurosurgery intensive care unit (ICU). Materials and Methods: This was a retrospective analysis of records of patients undergoing invasive mechanical ventilation in a neurosurgery ICU during a 3-month period. Results: Thirty-seven patients underwent invasive mechanical ventilation. The mean age was 56 years. Hypertension was the most common comorbidity among 22 (59.4%) patients. The neurological diagnosis was traumatic brain injury in 19 cases, nontraumatic intracranial hemorrhage in 12 cases, and ischemic stroke in 6 cases. Twenty-one patients had respiratory sample culture positivity and 14 were clinical VAP. The total ventilator days assessed were 82. The clinical VAP rate was 170.7, and the probable VAP (PVAP) rate for the same period was 12.19. Among the 14 patients who developed clinical VAP, 13 (88%) were hospital acquired and caused by multidrug-resistant pathogens. Six patients died during their ICU stay. ICU stay of more than 7 days was significantly associated with a clinical VAP. Conclusions: VAE was found to correlate poorly with a clinical diagnosis of VAP. When used as a surveillance tool in an ICU, it was found to miss important infection-related events in ventilated patients.

Evaluating the Ventilation Performance of Single-Span Plastic Greenhouses with Continuous Screened Side Openings

Natural ventilation is the most cost-effective environmental control method for protected horticulture. To overcome the issues associated with high temperatures in greenhouses, analyzing their ventilation characteristics and maximizing their natural ventilation performance are essential. Therefore, in this study, the natural ventilation performance of arched single-span plastic greenhouses with screened side openings was empirically investigated. Three identical single-span plastic greenhouses were used in this study, each with different side-opening heights. Temperature and wind-speed data were collected, and the ventilation-volume flow rate was calculated considering both buoyancy and wind forces. The natural ventilation performance of the greenhouses was strongly and positively correlated with the ventilation-area ratio and outdoor wind speed. The ventilation rate increased linearly with an increase in the ventilation-area ratio and high outdoor wind speeds. However, the association between ventilation performance and indoor–outdoor temperature differences was not strong. When the ratios of ventilation areas in the greenhouse were changed to 0.08, 0.19, and 0.29, the average indoor–outdoor temperature differences were 14.0, 10.1, and 7.7 °C, respectively, and the ventilation rates were 0.0081, 0.0196, and 0.0315 m3 s−1 m−2, respectively. The proportion of wind in the total ventilation performance was high with a low ratio of ventilation openings and high outdoor wind speeds. However, the proportion of the buoyancy was high, with a high ratio of ventilation openings and a large indoor–outdoor temperature difference. Overall, this study provides foundational insights for optimizing the design and evaluation of ventilation openings in greenhouses, considering the outdoor wind speed.

Methadone in combination with magnesium, ketamine, lidocaine, and dexmedetomidine improves postoperative outcomes after coronary artery bypass grafting: an observational multicentre study

BackgroundAn optimal pharmacological strategy for fast-track cardiac anesthesia (FTCA) is unclear. This study evaluated the effectiveness and safety of an FTCA program using methadone and non-opioid adjuvant infusions (magnesium, ketamine, lidocaine, and dexmedetomidine) in patients undergoing coronary artery bypass grafting.MethodsThis retrospective, multicenter observational study was conducted across private and public teaching sectors. We studied patients managed by a fast-track protocol or via usual care according to clinician preference. The primary outcome was the total mechanical ventilation time in hours adjusted for hospital, body mass index, category of surgical urgency, cardiopulmonary bypass time and EuroSCORE II. Secondary outcomes included successful extubation within four postoperative hours, postoperative pain scores, postoperative opioid requirements, and the development of postoperative complications.ResultsWe included 87 patients in the fast-track group and 88 patients in the usual care group. Fast-track patients had a 35% reduction in total ventilation hours compared with usual care patients (p = 0.007). Thirty-five (40.2%) fast-track patients were extubated within four hours compared to 10 (11.4%) usual-care patients (odds ratio: 5.2 [95% CI: 2.39–11.08; p < 0.001]). Over 24 h, fast-track patients had less severe pain (p < 0.001) and required less intravenous morphine equivalent (22.00 mg [15.75:32.50] vs. 38.75 mg [20.50:81.75]; p < 0.001). There were no significant differences observed in postoperative complications or length of hospital stay between the groups.ConclusionImplementing an FTCA protocol using methadone, dexmedetomidine, magnesium, ketamine, lignocaine, and remifentanil together with protocolized weaning from a mechanical ventilation protocol is associated with significantly reduced time to tracheal extubation, improved postoperative analgesia, and reduced opioid use without any adverse safety events. A prospective randomized trial is warranted to further investigate the combined effects of these medications in reducing complications and length of stay in FTCA.Trials registrationThe study protocol was registered in the Australian New Zealand Clinical Trials Registry (https://www.anzctr.org.au/ACTRN12623000060640.aspx, retrospectively registered on 17/01/2023).

Use of Early Ketamine Sedation and Association With Clinical and Cost Outcomes Among Mechanically Ventilated Patients With COVID-19: A Retrospective Cohort Study.

To describe the utilization of early ketamine use among patients mechanically ventilated for COVID-19, and examine associations with in-hospital mortality and other clinical outcomes. Retrospective cohort study. Six hundred ten hospitals contributing data to the Premier Healthcare Database between April 2020 and June 2021. Adults with COVID-19 and greater than or equal to 2 consecutive days of mechanical ventilation within 5 days of hospitalization. The exposures were early ketamine use initiated within 2 days of intubation and continued for greater than 1 day. Primary was hospital mortality. Secondary outcomes included length of stay (LOS) in the hospital and ICUs, ventilator days, vasopressor days, renal replacement therapy (RRT), and total hospital cost. The propensity score matching analysis was used to adjust for confounders. Among 42,954 patients, 1,423 (3.3%) were exposed to early ketamine use. After propensity score matching including 1,390 patients in each group, recipients of ketamine infusions were associated with higher hospital mortality (52.5% vs. 45.9%, risk ratio: 1.14, [1.06-1.23]), longer median ICU stay (13 vs. 12 d, mean ratio [MR]: 1.15 [1.08-1.23]), and longer ventilator days (12 vs. 11 d, MR: 1.19 [1.12-1.27]). There were no associations for hospital LOS (17 [10-27] vs. 17 [9-28], MR: 1.05 [0.99-1.12]), vasopressor days (4 vs. 4, MR: 1.04 [0.95-1.14]), and RRT (22.9% vs. 21.7%, RR: 1.05 [0.92-1.21]). Total hospital cost was higher (median $72,481 vs. $65,584, MR: 1.11 [1.05-1.19]). In a diverse sample of U.S. hospitals, about one in 30 patients mechanically ventilated with COVID-19 received ketamine infusions. Early ketamine may have an association with higher hospital mortality, increased total cost, ICU stay, and ventilator days, but no associations for hospital LOS, vasopressor days, and RRT. However, confounding by the severity of illness might occur due to higher extracorporeal membrane oxygenation and RRT use in the ketamine group. Further randomized trials are needed to better understand the role of ketamine infusions in the management of critically ill patients.

The Performance of Extracorporeal Membrane Oxygenation in Various Viral Pneumonia Pandemics: A Meta-Analysis and Systematic Review

Objective: To compare the effects of extracorporeal membrane oxygenation (ECMO) and routine mechanical ventilation on mortality and the risk of associated adverse events in patients with severe viral pneumonia. Methods: PubMed, the Cochrane Library, Embase, Web of Science, and other databases were searched to collect case-control or cohort studies on prognoses associated with ECMO treatment for viral pneumonia. Search terms included extracorporeal membrane oxygenation, ECMO, viral pneumonia, COVID-19, influenza, MERS, and others. According to the PICOS principle, two evaluators independently screened the literature, extracted the data, cross-checked the data, and extracted the data again. Two researchers evaluated the risk of bias in the included studies according to the Newcastle-Ottawa Scale (NOS) and cross-checked the results. Meta-analysis was performed using RevMan 5.3 software. Results: Nine studies were included for analysis, encompassing a total of 4,330 patients, which were categorized into ECMO and CMV groups. There were no significant differences between the two groups in most baseline data; however, the ECMO group had a lower oxygenation index, and some studies reported higher SOFA scores in the ECMO group compared to the CMV group. There was no significant difference in in-hospital mortality between the two groups. The length of ICU stay, total hospital stay, and total mechanical ventilation time were longer in the ECMO group than in the CMV group. In terms of adverse events, there was no significant difference in the occurrence of kidney injury between the two groups. Bleeding events were reported in two studies, with more bleeding events occurring in the ECMO group. According to the subgroup analysis of different virus types, there were no statistical differences in the above aspects among patients with swine flu, novel coronavirus, and MERS. Conclusion: ECMO has a certain degree of positive significance in the treatment of severe viral pneumonia, but there is no significant difference in the treatment outcome of ECMO across different epidemic periods. The timing of ECMO treatment, patient management, and withdrawal evaluation still need further research.

Chronic, episodic nicotine exposure enhances the hypoxic ventilatory response in adult female rats

It is well known that cigarette smoking causes lung disease and damages the airways. However, we know little about the direct role of nicotine, the primary addictive component of tobacco, in the development of smoking- related diseases. Along with promoting cancer cell proliferation and airway inflammation, nicotine can modulate central respiratory control, increasing the rate and depth of breathing through mechanisms that are not well understood. In addition, cigarette smoking is associated with obstructive sleep apnea, a sleep-related breathing disorder that is marked by reduced brainstem respiratory motor output. Despite these examples indicating that chronic nicotine exposure in adulthood may alter central respiratory control, there is no published research that directly tests this hypothesis. We exposed male and female adult rats to nicotine for four weeks through their drinking water and then used whole body plethysmography to test the hypothesis that chronic, episodic nicotine exposure alters restful breathing and the hypoxic ventilatory response (HVR), a critical respiratory chemoreflex. We measured tidal volume (TV) and frequency of breathing at rest, and during a 5- minute episode of hypoxia (10% oxygen/balance nitrogen). Total ventilation (VE/VCO2) was calculated as TV X Frequency and normalized to carbon dioxide production, to account for changes in metabolism, and body weight. For both males and females, comparisons were made between groups and across trials using a 2-way ANOVA and Tukey’s post-hoc test. In male rats, nicotine exposure significantly decreased overall ventilation at rest in one of three trials (Trial 1 VE/VCO2: Nicotine exposed, 30.7±7.5 mL/min/100g, Control, 44.3±6.4 mL/min/100g, p=0.0183), but had no effect on breathing during hypoxia. In female rats, nicotine exposure had no effect on breathing at rest, however, overall ventilation during hypoxia was enhanced in nicotine exposed rats compared to controls in two of three trials (Trial 1 VE/VCO2: Nicotine exposed, 106.8±20.6 mL/min/100g, Control, 79.8±5.1 mL/min/100g, p=0.049; Trial 3 VE/VCO2: Nicotine exposed, 101.6±9.9 mL/min/100g, Control, 68.1±10.9 mL/min/100g, p=0.007). Overall, these results suggest that chronic nicotine exposure triggers plasticity in the chemoreflex pathway mediating the HVR in a sex specific manner and further studies are warranted to understand the implications of this finding. 1K99HL164973-02. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Risk factors for the failure of ibuprofen treatment in preterm infants with hemodynamically significant patent ductus arteriosus

To investigate the risk factors for the failure of ibuprofen treatment in preterm infants with hemodynamically significant patent ductus arteriosus (hsPDA). A retrospective collection of clinical data was conducted on preterm infants with a gestational age of <34 weeks who were diagnosed with hsPDA and treated at the Department of Neonatology, Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, from January 2018 to June 2023. The subjects were divided into two groups based on the treatment approach: the ibuprofen group (95 cases) and the ibuprofen plus surgery group (44 cases). The risk factors for the failure of ibuprofen treatment in preterm infants with hsPDA were identified by binary logistic regression analysis. The binary logistic regression analysis revealed that an increased diameter of the ductus arteriosus, a resistance index (RI) value of the middle cerebral artery ≥0.80, and prolonged total invasive mechanical ventilation time were risk factors for the failure of ibuprofen treatment in preterm infants with hsPDA (P<0.05). Receiver operating characteristic curve analysis showed that a ductus arteriosus diameter >2.85 mm, a middle cerebral artery RI value ≥0.80, and a total invasive mechanical ventilation time >16 days had significant predictive value for the failure of ibuprofen treatment in preterm infants with hsPDA (P<0.05). The combined predictive value of these three factors was the highest, with an area under the curve of 0.843, a sensitivity of 86.5%, and a specificity of 75.0% (P<0.05). A ductus arteriosus diameter >2.85 mm, a middle cerebral artery RI value ≥0.80, and a total invasive mechanical ventilation time >16 days are risk factors for the failure of ibuprofen treatment in preterm infants with hsPDA, and they are of significant predictive value for the necessity of surgical treatment following the failure of ibuprofen treatment.

Impact of wind on solar-induced natural ventilation through double-skin facade

Although wind-buoyancy interactions have been widely explored, their mixing associated with semi-transparent facades are not yet clearly understood. This gap greatly restraints the implementation of naturally ventilated double-skin facades (NVDSFs). In this study, the impact of wind on the buoyancy flow in an NVDSF was investigated on a range of wind speeds, wind angles, and solar radiation intensities. The wind's realistic impinging associated with solar radiation's transportation between facades are revealed. Results present three aspects: the impact of wind on façade temperatures; the counteraction of wind on buoyant outflow; and defining and correlating the ‘critical wind velocity’ according to targeted natural ventilation rates. Results correlated the additional temperature drops on the outer glazing for wind speed 0.125–1.0 m/s, attack angles 5° ∼ 85° and solar radiation between 200–1000W/m2. The wind at 1 m/s and 5° can cause 10.5% reduction in façade temperature. By proposing a ‘wind inflow coefficient’, we established an empirical model to calculate the total ventilation rate under the mixed wind-buoyancy effect. Furthermore, an important concept – ‘critical wind velocity’, was introduced accordingly. It indicates the wind velocity under which the targeted natural ventilation can be met for an NVDSF for different solar conditions, e.g. the velocity at which the wind cancels out the buoyant outflow or below which the indoor ventilation can be satisfied. The novel correlations for the combination of mixed wind-buoyancy field with solar radiation and glazing materials can contribute significantly to NVDSFs under realistic environmental conditions.

Clinical observation of the long-term course of COVID-19 infection in a patient with an immunodeficiency condition

The new coronavirus infection caused by the SARS-CoV-2 virus has become a real challenge for the world’s population. Despite the fact that vaccines have been developed and the effectiveness of antiviral drugs has been demonstrated, COVID-19 continues to be an urgent problem. SARS-CoV-2 is genetically modified due to the accumulation of mutations, new strains with high virulence appear that distort the immune response. In addition, it has been shown that the virus can persist in the body for a long time, which ensures the maintenance of an inflammatory response and causes the persistence and recurrence of symptoms after acute infection, especially in certain groups of patients. The article presents a clinical case of a long-term course of new coronavirus infection with predominant lung damage in the form of interstitial changes and persistent inflammation for 7 months from the moment of diagnosis against the background of an immunodeficiency condition due to the patient’s lymphoma in remission after polychemotherapy, exclusion of pulmonary embolism and progression of lymphoproliferative disease. The article highlights the difficulties of determining the criteria for a post-COVID and the features of its treatment using long-term therapy with systemic glucocorticosteroids, inhalation administration of tauractant (Surfactant-BL) in comparison with the dynamic assessment of total ventilation disorders and dynamic control of MSCT of the chest organs. Thus, the importance of identifying risk factors for the progression of COVID-19-associated conditions in patients with different comorbid backgrounds and identifying criteria for the development of new long-COVID treatment strategies is emphasized.

HYBRID VASCULAR APPROACH REDUCES THE INTENSIVE CARE UNIT STAY IN PATIENTS WITH CHRONICALLY THREATENING LIMB ISCHEMIA AND MULTILEVEL ATHEROSCLEROTIC LESIONS

Chronic limb-threatening ischemia represents the fi nal stage of atherosclerosis and is often associated with signifi cantcardiovascular morbidity leading to high mortality. The hybrid approach combines surgical and endovascular techniques toachieve maximal revascularization of multilevel atherosclerotic lesions in the lower limb, with a shorter procedure time and less trauma compared to the classical method. It is also expected to reduce the length of hospital stay.The aim of the study is to analyze the relationship between the hybrid approach and the length of stay in the intensive careunit (ICU) compared to the classical vascular surgical approach in patients with chronic limb-threatening ischemia, multilevel atherosclerosis and high anesthesiological risk. Another endpoint is to compare the total ventilation time in the two groups.Material and methods. The study compares ICU length of stay and total mechanical ventilation time between two groups –a prospective group (n=48) of patients treated with hybrid revascularization and a control group (n=50) treated with classicalvascular revascularization. Patients included had multi- level atherosclerotic lesions (aorta- iliac, femur- popliteal and outfl ow) and chronic limb-threatening ischemia (Fontaine Grade III and IV). A database was created with subsequent statistical analysis using «SPSS» software. Tests used: Chi-square, p-value, frequencies. The chi-squared test was considered valid if the test statistic is chi-squared distributed under the null hypothesis, specifi cally Pearson’s chi-squared test. If the null hypothesis that there are no diff erences between classes in the population is true, the test statistic calculated from the observations follows a χ2 frequency distribution. If the p-value is greater than alpha, then we have not rejectedthe null hypothesis and assume that there is no signifi cant diff erence between the two samples. We set the signifi cance level at 0.05. The study protocol was approved by the Commission on Biomedical Ethics of the Bukovinian State Medical University (minutes of the Commission meeting No 4 from the 19.12.2023 year). The theme of the complex research work «Development, justifi cation and implementation of new approaches to the diagnosis and treatment of some acute surgical diseases, prediction of their course and prevention of complications (state registration number: 0121U110501, terms of execution: 01.2021-12.0225).Results. ICU length of stay and total ventilation time were analyzed in the two groups. Both ICU and total ventilation timeswere shorter with statistical signifi cance in the hybrid approach group. Therefore, the use of hybrid revascularization contributes to an accelerated stabilization of the patient’s condition. Therefore, the use of the hybrid vascular approach contributes to an accelerated stabilization of the patient’s condition. This reduces the duration of treatment, the cost of treatment. So, hybrid vascular approach is a promising way to treat limb ischemia. This approach needs further implementation in practice. The novelty added by the manuscript to the already published scientifi c literature: Hybrid revascularization itself represents a relatively new type of treatment for patients with multilevel atherosclerotic lesions. The analysis of the length of stay in the intensive care unit of patients undergoing hybrid revascularization compared to classic surgical revascularization adds to the current literature.Conclusions. ICU length of stay for patients with chronic limb-threatening ischemia and multilevel atherosclerosis, as wellas total mechanical ventilation time, is shorter with statistical signifi cance when hybrid revascularization is used compared with traditional vascular surgery.