Ventilatory Mechanics in the Patient with Obesity

Association between waist circumference and lung function in American middle-aged and older adults: findings from NHANES 2007-2012

PURPOSE

There is a major epidemic of obesity, and many obese patients suffer from respiratory symptoms and disease. However, limited research explores the associations between abdominal obesity and lung function indices, yielding mixed results. This study aims to analyze the association between waist circumference (WC), an easily measurable marker of abdominal obesity, and lung function parameters in middle-aged and older adults using the National Health and Nutrition Examination Survey (NHANES).

METHODS

This study utilized data obtained from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2012, with a total sample size of 6089 individuals. A weighted multiple regression analysis was conducted to assess the relationship between WC and three pulmonary function parameters. Additionally, a weighted generalized additive model and smooth curve fitting were applied to capture any potential nonlinear relationship within this association.

RESULTS

After considering all confounding variables, it was observed that for each unit increase in WC, in males, Forced Vital Capacity (FVC) increased by 23.687 ml, Forced Expiratory Volume in one second (FEV1) increased by 12.029 ml, and the FEV1/FVC ratio decreased by 0.140%. In females, an increase in waist circumference by one unit resulted in an FVC increase of 6.583 ml and an FEV1 increase of 4.453 ml. In the overall population, each unit increase in waist circumference led to a FVC increase of 12.014 ml, an FEV1 increase of 6.557 ml, and a decrease in the FEV1/FVC ratio by 0.076%. By constructing a smooth curve, we identified a positive correlation between waist circumference and FVC and FEV1. Conversely, there was a negative correlation between waist circumference and the FEV1/FVC ratio.

CONCLUSIONS

Our findings indicate that in the fully adjusted model, waist circumference, independent of BMI, positively correlates with FVC and FEV1 while exhibiting a negative correlation with FEV1/FVC among middle-aged and older adults in the United States. These results underscore the importance of considering abdominal obesity as a potential factor influencing lung function in American middle-aged and older adults.

Obesity and anesthesia

PURPOSE OF REVIEW

Surgical procedures on obese patients are dramatically increasing worldwide over the past few years. In this review, we discuss the physiopathology of predominantly respiratory system in obese patients, the importance of preoperative evaluation, preoxygenation and intraoperative positive end expiratory pressure (PEEP) titration to prevent pulmonary complications and the optimization of airway management and oxygenation to reduce or prevent postoperative respiratory complications.

RECENT FINDINGS

Many patients are coming to preoperative clinic with medication history of glucagon-like-peptide 1 agonists ( GLP-1) agonists and it has raised many questions regarding Nil Per Os (NPO)/perioperative fasting guidelines due to delayed gastric emptying caused by these medications. American Society of Anesthesiologists (ASA) has come up with guiding document to help with such situations. Ambulatory surgery centers are doing more obesity cases in a safe manner which were deemed unsafe at one point . Quantitative train of four (TOF) monitoring, better neuromuscular reversal agents and gastric ultrasounds seemed to have made a significant impact in the care of obese patients in the perioperative period.

SUMMARY

Obese patients are at higher risk of perioperative complications, mainly associated with those related to the respiratory function. An appropriate preoperative evaluation, intraoperative management, and postoperative support and monitoring is essential to improve outcome and increase the safety of the surgical procedure.

Associations of obesity with chronic inflammatory airway diseases and mortality in adults: a population-based investigation

BACKGROUND

The association between obesity and respiratory diseases has been confirmed. However, few studies have reported the relationship between obesity and the risk and mortality of chronic inflammatory airway disease (CIAD). The aim of this study was to reveal the association between obesity and the risk of CIAD, and mortality in patients with CIAD.

METHODS

The study was conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2013 to 2018 among adults aged 20 years and above. All participants were grouped according to body mass index (BMI) and waist circumference (WC) levels to study the relationship between obesity and CIAD. Multivariate logistic regression analysis was utilized to examine the connection between CIAD and obesity in a cross-sectional study. The association between obesity and all-cause mortality in individuals with CIAD was examined using multiple cox regression models and smooth curve fitting in a prospective cohort study.

RESULTS

When stratified based on BMI in comparison to the normal weight group, the ORs with 95%CIs of CIAD for underweight and obesity were 1.39 (1.01-1.93) and 1.42 (1.27-1.58), respectively. The OR with 95%CI of CIAD for obesity was 1.20 (1.09-1.31) when stratified according to WC. Additionally, underweight was associated with a higher mortality (HR = 2.44, 95% CI = 1.31-4.55), whereas overweight (HR = 0.58,95% CI = 0.39-0.87) and obesity (HR = 0.59,95% CI = 0.4-0.87) were associated with a lower mortality (P for trend < 0.05). There was a non-linear association between BMI and all-cause mortality (P for non-linear = 0.001). An analysis of a segmentation regression model between BMI and all-cause mortality revealed a BMI turning point value of 32.4 kg/m2. The mortality of CIAD patients was lowest when BMI was 32.4 kg/m2. When BMI ≤ 32.4 kg/m2, BMI was inversely associated with all-cause mortality in patients with CIAD (HR: 0.92, 95%CI:0.88-0.97). However, when BMI > 32.4 kg/m2, there was no association between BMI and all-cause mortality (HR:1.02, 95%CI:0.97-1.06).

CONCLUSION

Compared to normal weight, underweight and obesity were associated with the increased risk of CIAD. Underweight was associated with increased all-cause mortality, while overweight was associated with reduced all-cause mortality. There was a non-linear association between BMI and all-cause mortality in patients with CIAD. The all-cause mortality was lowest when BMI was 32.4 kg/m2.

Incidence of Weaning Failure in Obese Patients in Intensive Care Unit

Background The escalating prevalence of obesity worldwide presents unique challenges in critical care management, especially in the context of mechanical ventilation and weaning processes in intensive care units (ICUs). The present study aimed to determine the incidence of weaning failure in obese patients in an ICU. Methods A prospective observational study was carried out to gather data on patients in the ICU of Shifa International Hospital located in Islamabad, Pakistan. The target population consisted of adult patients who were both male and female, ages 18 years and above. These individuals required intubation procedures as well as mechanical ventilation during their hospitalization. The researchers followed these patients prospectively and observed their medical conditions closely to gather data about how obesity might impact critical care interventions and outcomes. Results The sample size was 288 bearing a median age of 61.0 with an interquartile range of 19 years. Older age manifested a significantly higher frequency of failed extubation (p=0.065). Higher body mass index (BMI) was significantly associated with failed extubation among the study population. It was found that a higher significant difference was associated with BMI > 30 kg/m2 (obese) in failed and successful extubation. One-half of the patients with failed extubation and only 16 (5.9%) patients with successful extubation had end-stage renal disease (p<0.001). It was found that patients who underwent failed extubation had notably increased ICU mortality (p=0.108), 28-day mortality (p=0.067), as well as mean ICU (p<0.001) and hospital stay (p=0.007). Conclusion Our study revealed some insightful correlations between obesity, age, comorbidities, length of hospitalization, ICU stay, and mortality rate in terms of weaning failure among the study population.

Optimal positive-end expiratory pressure weaning in acute respiratory distress syndrome patients

PURPOSE OF REVIEW

Positive-end expiratory pressure (PEEP) is a tool in managing acute respiratory distress syndrome (ARDS). In this review, we discuss the various approaches to weaning PEEP after the acute phase of ARDS.

RECENT FINDINGS

There is a paucity of research specifically looking at the differences between PEEP weaning protocols. Data in some populations though, particularly those with elevated BMI, suggest that a physiologic approach to PEEP weaning may be helpful. Use of various tools to optimize PEEP prior to and during spontaneous breathing trials (SBTs) may allow for improved alveolar recruitment and respiratory outcomes.

SUMMARY

Although further prospective studies are warranted, we should consider using a physiologic approach to PEEP weaning in ARDS rather than a one size fits all model, which is currently the standard used in many clinical trials and throughout many ICUs.

Obesity and Extracorporeal Membrane Oxygenation (ECMO): Analysis of Outcomes

Traditionally, patients with obesity have been deemed ineligible for extracorporeal life support (ELS) therapies such as extracorporeal membrane oxygenation (ECMO), given the association of obesity with chronic health conditions that contribute to increased morbidity and mortality. Nevertheless, a growing body of literature suggests the feasibility, efficacy, and safety of ECMO in the obese population. This review provides an in-depth analysis of the current literature assessing the effects of obesity on outcomes among patients supported with ECMO (venovenous [VV] ECMO in noncoronavirus disease 2019 and coronavirus disease 2019 acute respiratory distress syndrome, venoarterial [VA] ECMO, and combined VV and VA ECMO), offer a possible explanation of the current findings on the basis of the obesity paradox phenomenon, provides a framework for future studies addressing the use of ELS therapies in the obese patient population, and provides guidance from the literature for many of the challenges related to initiating, maintaining, and weaning ELS therapy in patients with obesity.

Acute Respiratory Failure Complicating Endoscopic Sleeve Gastroplasty: A Case Report

Endoscopic sleeve gastroplasty (ESG) is a safe and minimally invasive procedure for the treatment of obesity. We report the case of a patient with obesity who underwent ESG complicated by postprocedural respiratory failure. During the procedure, she developed a Pao2/fraction of inspired oxygen (Fio2) ratio that necessitated postoperative mechanical ventilation. Chest radiography demonstrated massively dilated loops of bowel, cephalad displacement of both hemidiaphragms, lung volume reduction, and atelectasis. With absorption of luminal carbon dioxide, she was weaned from mechanical ventilation to supplemental oxygen, and she recovered completely. This case highlights postoperative respiratory failure associated with mechanical loading of the respiratory system following ESG.

Individualized Positive End-expiratory Pressure Titration Strategies in Superobese Patients Undergoing Laparoscopic Surgery: Prospective and Nonrandomized Crossover Study

BACKGROUND

Superobesity and laparoscopic surgery promote negative end-expiratory transpulmonary pressure that causes atelectasis formation and impaired respiratory mechanics. The authors hypothesized that end-expiratory transpulmonary pressure differs between fixed and individualized positive end-expiratory pressure (PEEP) strategies and mediates their effects on respiratory mechanics, end-expiratory lung volume, gas exchange, and hemodynamic parameters in superobese patients.

METHODS

In this prospective, nonrandomized crossover study including 40 superobese patients (body mass index 57.3 ± 6.4 kg/m2) undergoing laparoscopic bariatric surgery, PEEP was set according to (1) a fixed level of 8 cm H2O (PEEPEmpirical), (2) the highest respiratory system compliance (PEEPCompliance), or (3) an end-expiratory transpulmonary pressure targeting 0 cm H2O (PEEPTranspul) at different surgical positioning. The primary endpoint was end-expiratory transpulmonary pressure at different surgical positioning; secondary endpoints were respiratory mechanics, end-expiratory lung volume, gas exchange, and hemodynamic parameters.

RESULTS

Individualized PEEPCompliance compared to fixed PEEPEmpirical resulted in higher PEEP (supine, 17.2 ± 2.4 vs. 8.0 ± 0.0 cm H2O; supine with pneumoperitoneum, 21.5 ± 2.5 vs. 8.0 ± 0.0 cm H2O; and beach chair with pneumoperitoneum; 15.8 ± 2.5 vs. 8.0 ± 0.0 cm H2O; P < 0.001 each) and less negative end-expiratory transpulmonary pressure (supine, -2.9 ± 2.0 vs. -10.6 ± 2.6 cm H2O; supine with pneumoperitoneum, -2.9 ± 2.0 vs. -14.1 ± 3.7 cm H2O; and beach chair with pneumoperitoneum, -2.8 ± 2.2 vs. -9.2 ± 3.7 cm H2O; P < 0.001 each). Titrated PEEP, end-expiratory transpulmonary pressure, and lung volume were lower with PEEPCompliance compared to PEEPTranspul (P < 0.001 each). Respiratory system and transpulmonary driving pressure and mechanical power normalized to respiratory system compliance were reduced using PEEPCompliance compared to PEEPTranspul.

CONCLUSIONS

In superobese patients undergoing laparoscopic surgery, individualized PEEPCompliance may provide a feasible compromise regarding end-expiratory transpulmonary pressures compared to PEEPEmpirical and PEEPTranspul, because PEEPCompliance with slightly negative end-expiratory transpulmonary pressures improved respiratory mechanics, lung volumes, and oxygenation while preserving cardiac output.

EDITOR’S PERSPECTIVE

Remimazolam Induction in a Patient with Super-Super Obesity and Obstructive Sleep Apnea: A Case Report

Background: With the rising prevalence of obesity, anesthesiologists are expected to increasingly encounter patients with obesity, which poses challenges for anesthetic management. The use of remimazolam, an intravenous anesthetic agent approved in 2020, may be beneficial in these patients. However, its use in patients with super-super obesity remains underexplored. Case Description: A 55-year-old woman with a body mass index (BMI) of 60.6 kg/m² and moderate obstructive sleep apnea (OSA) underwent laparoscopic sleeve gastrectomy under general anesthesia. The transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) technique was used along with the administration of remimazolam at a rate of 6 mg/kg/h based on the total body weight. The patient was sedated within 125 s without any signs of hemodynamic instability, and the surgery was completed successfully. Conclusions: This case study demonstrates the potential effectiveness of remimazolam infusion for inducing general anesthesia in patients with super-super obesity. The infusion rate, derived from the total body weight, yielded an outcome comparable with that observed in individuals without obesity. Further studies with larger cohorts are required to confirm these findings.

Effects of obesity, pneumoperitoneum, and body position on mechanical power of intraoperative ventilation: an observational study

Mechanical power can describe the complex interaction between the respiratory system and the ventilator and may predict lung injury or pulmonary complications, but the power associated with injury of healthy human lungs is unknown. Body habitus and surgical conditions may alter mechanical power but the effects have not been measured. In a secondary analysis of an observational study of obesity and lung mechanics during robotic laparoscopic surgery, we comprehensively quantified the static elastic, dynamic elastic, and resistive energies comprising mechanical power of ventilation. We stratified by body mass index (BMI) and examined power at four surgical stages: level after intubation, with pneumoperitoneum, in Trendelenburg, and level after releasing the pneumoperitoneum. Esophageal manometry was used to estimate transpulmonary pressures. Mechanical power of ventilation and its bioenergetic components increased over BMI categories. Respiratory system and lung power were nearly doubled in subjects with class 3 obesity compared with lean at all stages. Power dissipated into the respiratory system was increased with class 2 or 3 obesity compared with lean. Increased power of ventilation was associated with decreasing transpulmonary pressures. Body habitus is a prime determinant of increased intraoperative mechanical power. Obesity and surgical conditions increase the energies dissipated into the respiratory system during ventilation. The observed elevations in power may be related to tidal recruitment or atelectasis, and point to specific energetic features of mechanical ventilation of patients with obesity that may be controlled with individualized ventilator settings.NEW & NOTEWORTHY Mechanical power describes the complex interaction between a patient's lungs and the ventilator and may be useful in predicting lung injury. However, its behavior in obesity and during dynamic surgical conditions is not understood. We comprehensively quantified ventilation bioenergetics and effects of body habitus and common surgical conditions. These data show body habitus is a prime determinant of intraoperative mechanical power and provide quantitative context for future translation toward a useful perioperative prognostic measurement.

Biomarkers as predictors of mortality in critically ill obese patients with COVID-19 at high altitude

BACKGROUND

Obesity is a common chronic comorbidity of patients with COVID-19, that has been associated with disease severity and mortality. COVID-19 at high altitude seems to be associated with increased rate of ICU discharge and hospital survival than at sea-level, despite higher immune levels and inflammation. The primary aim of this study was to investigate the survival rate of critically ill obese patients with COVID-19 at altitude in comparison with overweight and normal patients. Secondary aims were to assess the predictive factors for mortality, characteristics of mechanical ventilation setting, extubation rates, and analytical parameters.

METHODS

This is a retrospective cohort study in critically ill patients with COVID-19 admitted to a hospital in Quito-Ecuador (2,850 m) from Apr 1, 2020, to Nov 1, 2021. Patients were cathegorized as normal weight, overweight, and obese, according to body mass index [BMI]).

RESULTS

In the final analysis 340 patients were included, of whom 154 (45%) were obese, of these 35 (22.7%) were hypertensive and 25 (16.2%) were diabetic. Mortality in obese patients (31%) was lower than in the normal weight (48%) and overweight (40%) groups, but not statistically significant (p = 0.076). At multivariable analysis, in the overall population, older age (> 50 years) was independent risk factor for mortality (B = 0.93, Wald = 14.94, OR = 2.54 95%CI = 1.58-4.07, p < 0.001). Ferritin and the neutrophil/lymphocyte ratio were independent predictors of mortality in obese patients. Overweight and obese patients required more positive and-expiratory pressure compared to normal-weight patients. In obese patients, plateau pressure and mechanical power were significantly higher, whereas extubation failure was lower as compared to overweight and normal weight.

CONCLUSIONS

This preliminary study suggests that BMI was not associated with mortality in critically ill patients at high altitude. Age was associated with an increase in mortality independent of the BMI. Biomarkers such as ferritin and neutrophils/lymphocytes ratio were independent predictors of mortality in obese patients with COVID-19 at high altitude.

Driving Pressure, Elastance, and Outcomes in a Real-World Setting: A Bi-Center Analysis of Electronic Health Record Data

Emerging evidence suggests the potential importance of inspiratory driving pressure (DP) and respiratory system elastance (E_RS) on outcomes among patients with the acute respiratory distress syndrome. Their association with outcomes among heterogeneous populations outside of a controlled clinical trial is underexplored. We used electronic health record (EHR) data to characterize the associations of DP and E_RS with clinical outcomes in a real-world heterogenous population.

DESIGN

Observational cohort study.

SETTING

Fourteen ICUs in two quaternary academic medical centers.

PATIENTS

Adult patients who received mechanical ventilation for more than 48 hours and less than 30 days.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

EHR data from 4,233 ventilated patients from 2016 to 2018 were extracted, harmonized, and merged. A minority of the analytic cohort (37%) experienced a Pao₂/Fio₂ of less than 300. A time-weighted mean exposure was calculated for ventilatory variables including tidal volume (V_T), plateau pressures (P_PLAT), DP, and E_RS. Lung-protective ventilation adherence was high (94% with V_T < 8.5 mL/kg, time-weighted mean V_T = 6. 8 mL/kg, 88% with P_PLAT ≤ 30 cm H₂O). Although time-weighted mean DP (12.2 cm H₂O) and E_RS (1.9 cm H₂O/[mL/kg]) were modest, 29% and 39% of the cohort experienced a DP greater than 15 cm H₂O or an E_RS greater than 2 cm H₂O/(mL/kg), respectively. Regression modeling with adjustment for relevant covariates determined that exposure to time-weighted mean DP (> 15 cm H₂O) was associated with increased adjusted risk of mortality and reduced adjusted ventilator-free days independent of adherence to lung-protective ventilation. Similarly, exposure to time-weighted mean E_RS greater than 2 cm H₂O/(mL/kg) was associated with increased adjusted risk of mortality.

CONCLUSIONS

Elevated DP and E_RS are associated with increased risk of mortality among ventilated patients independent of severity of illness or oxygenation impairment. EHR data can enable assessment of time-weighted ventilator variables and their association with clinical outcomes in a multicenter real-world setting.

Anesthesia Machine and New Modes of Ventilation

Mechanical ventilation is ubiquitous in the operating room. This article explores the anesthesia machine as a ventilator, examining its unique features and differences from ventilators designed for long-term use. It will describe standard and nonstandard modes of ventilation. The reader will develop a more nuanced understanding of how to tailor ventilation and oxygenation strategies based on patient and anesthetic scenarios as well as with the assistance of new technologies.

Distribution of ventilation and oxygenation in surgical obese patients ventilated with high versus low positive end-expiratory pressure: A substudy of a randomised controlled trial

BACKGROUND

Intra-operative ventilation using low/physiological tidal volume and positive end-expiratory pressure (PEEP) with periodic alveolar recruitment manoeuvres (ARMs) is recommended in obese surgery patients.

OBJECTIVES

To investigate the effects of PEEP levels and ARMs on ventilation distribution, oxygenation, haemodynamic parameters and cerebral oximetry.

DESIGN

A substudy of a randomised controlled trial.

SETTING

Tertiary medical centre in Geneva, Switzerland, between 2015 and 2018.

PATIENTS

One hundred and sixty-two patients with a BMI at least 35 kg per square metre undergoing elective open or laparoscopic surgery lasting at least 120 min.

INTERVENTION

Patients were randomised to PEEP of 4 cmH 2 O ( n  = 79) or PEEP of 12 cmH 2 O with hourly ARMs ( n  = 83).

MAIN OUTCOME MEASURES

The primary endpoint was the fraction of ventilation in the dependent lung as measured by electrical impedance tomography. Secondary endpoints were the oxygen saturation index (SaO 2 /FIO 2 ratio), respiratory and haemodynamic parameters, and cerebral tissue oximetry.

RESULTS

Compared with low PEEP, high PEEP was associated with smaller intra-operative decreases in dependent lung ventilation [-11.2%; 95% confidence interval (CI) -8.7 to -13.7 vs. -13.9%; 95% CI -11.7 to -16.5; P  = 0.029], oxygen saturation index (-49.6%; 95% CI -48.0 to -51.3 vs. -51.3%; 95% CI -49.6 to -53.1; P  < 0.001) and a lower driving pressure (-6.3 cmH 2 O; 95% CI -5.7 to -7.0). Haemodynamic parameters did not differ between the groups, except at the end of ARMs when arterial pressure and cardiac index decreased on average by -13.7 mmHg (95% CI -12.5 to -14.9) and by -0.54 l min -1  m -2 (95% CI -0.49 to -0.59) along with increased cerebral tissue oximetry (3.0 and 3.2% on left and right front brain, respectively).

CONCLUSION

In obese patients undergoing abdominal surgery, intra-operative PEEP of 12 cmH 2 O with periodic ARMs, compared with intra-operative PEEP of 4 cmH 2 O without ARMs, slightly redistributed ventilation to dependent lung zones with minor improvements in peripheral and cerebral oxygenation.

TRIAL REGISTRATION

NCT02148692, https://clinicaltrials.gov/ct2.

Lifestyle and environmental factors may induce airway and systemic inflammation in firefighters

Health status depends on multiple genetic and non-genetic factors. Nonheritable factors (such as lifestyle and environmental factors) have stronger impact on immune responses than genetic factors. Firefighters work is associated with exposure to air pollution and heat stress, as well as: extreme physical effort, mental stress, or a changed circadian rhythm, among others. All these factors can contribute to both, short-term and long-term impairment of the physical and mental health of firefighters. Increased levels of some inflammatory markers, such as pro-inflammatory cytokines or C-reactive protein (CRP) have been observed in firefighters, which can lead to local, acute inflammation that promotes a systemic inflammatory response. It is worth emphasizing that inflammation is one of the main hallmarks of cancer and also plays a key role in the development of cardiovascular and respiratory diseases. This article presents possible causes of the development of an inflammatory reaction in firefighters, with particular emphasis on airway inflammation caused by smoke exposure.

Individualized positive end-expiratory pressure with and without recruitment maneuvers in obese patients during bariatric surgery

This study aimed to determine whether regular recruitment maneuvers (RMs) are essential for obese patients (OPs) undergoing elective laparoscopic bariatric surgery (LBS) during intraoperative ventilation with individualized positive end-expiratory pressure (PEEP). Patients were randomly assigned to two arms: the RM + PEEP_-EIT arm consisted of individualized PEEP titrated by electrical impedance tomography (EIT) with two regular RMs and the PEEP_-EIT arm consisted of individualized PEEP titrated by EIT without additional RMs. For these two arms together, EIT-guided PEEP varied among individuals. The partial pressure of oxygen in arterial blood to fractional inspired oxygen (PaO₂ /FiO₂ ) ratio in the RM + PEEP_-EIT arm was higher than that in the PEEP_-EIT arm at 1 h after pneumoperitoneum (p = 0.024) and at the end of surgery (p = 0.035). There was no great difference in the PaO₂ /FiO₂ ratio between these two arms when measured 5 min prior to postanesthesia care unit (PACU) departure and on postoperative day 1. Compared with the PEEP_-EIT arm, patients in the RM + PEEP_-EIT arm had significantly higher intraoperative dynamic respiratory system compliance (p < 0.001) but consumed more vasopressors (p = 0.036). Postoperative pulmonary complications occurred in 1 of 29 patients in the RM + PEEP_-EIT arm compared with 2 of 31 patients in the PEEP_-EIT arm. Regular lung RMs can improve intraoperative oxygenation and respiratory system compliance among OPs undergoing LBS with EIT-guided individual PEEP. However, the improvement might disappear before leaving the PACU, and regular RMs resulted in more vasopressor consumption.

Adipose Tissue Inflammation and Pulmonary Dysfunction in Obesity

Obesity is a chronic disease caused by an excess of adipose tissue that may impair health by altering the functionality of various organs, including the lungs. Excessive deposition of fat in the abdominal area can lead to abnormal positioning of the diaphragm and consequent reduction in lung volume, leading to a heightened demand for ventilation and increased exposure to respiratory diseases, such as chronic obstructive pulmonary disease, asthma, and obstructive sleep apnoea. In addition to mechanical ventilatory constraints, excess fat and ectopic deposition in visceral depots can lead to adipose tissue dysfunction, which promotes metabolic disorders. An altered adipokine-secretion profile from dysfunctional adipose tissue in morbid obesity fosters systemic, low-grade inflammation, impairing pulmonary immune response and promoting airway hyperresponsiveness. A potential target of these adipokines could be the NLRP3 inflammasome, a critical component of the innate immune system, the harmful pro-inflammatory effect of which affects both adipose and lung tissue in obesity. In this review, we will investigate the crosstalk between adipose tissue and the lung in obesity, highlighting the main inflammatory mediators and novel therapeutic targets in preventing pulmonary dysfunction.

The Exposome and Immune Health in Times of the COVID-19 Pandemic

Growing evidence supports the importance of lifestyle and environmental exposures-collectively referred to as the 'exposome'-for ensuring immune health. In this narrative review, we summarize and discuss the effects of the different exposome components (physical activity, body weight management, diet, sun exposure, stress, sleep and circadian rhythms, pollution, smoking, and gut microbiome) on immune function and inflammation, particularly in the context of the current coronavirus disease 2019 (COVID-19) pandemic. We highlight the potential role of 'exposome improvements' in the prevention-or amelioration, once established-of this disease as well as their effect on the response to vaccination. In light of the existing evidence, the promotion of a healthy exposome should be a cornerstone in the prevention and management of the COVID-19 pandemic and other eventual pandemics.

Evaluation of Lung Aeration and Respiratory System Mechanics in Obese Dogs Ventilated With Tidal Volumes Based on Ideal vs. Current Body Weight

We describe the respiratory mechanics and lung aeration in anesthetized obese dogs ventilated with tidal volumes (VT) based on ideal (VTi) vs. current (VTc) body weight. Six dogs with body condition scores ≥ 8/9 were included. End-expiratory respiratory mechanics and end-expiratory CT-scan were obtained at baseline for each dog. Thereafter, dogs were ventilated with VT 15 ml kg⁻¹ based on VTi and VTc, applied randomly. Respiratory mechanics and CT-scan were repeated at end-inspiration during VTi and VTc. Data analyzed with linear mixed models and reported as mean ± SD or median [range]. Statistical significance p < 0.05. The elastance of the lung, chest wall and respiratory system indexed by ideal body weight (IBW) were positively correlated with body fat percentage, whereas the functional residual capacity indexed by IBW was negatively correlated with body fat percentage. At end-expiration, aeration (%) was: hyperaeration 0.03 [0.00–3.35], normoaeration 69.7 [44.6–82.2], hypoaeration 29.3 [13.6–49.4] and nonaeration (1.06% [0.37–6.02]). Next to the diaphragm, normoaeration dropped to 12 ± 11% and hypoaeration increased to 90 ± 8%. No differences in aeration between groups were found at end-inspiration. Airway driving pressure (cm H₂O) was higher (p = 0.002) during VTc (9.8 ± 0.7) compared with VTi (7.6 ± 0.4). Lung strain was higher (p = 0.014) during VTc (55 ± 21%) than VTi (38 ± 10%). The stress index was higher (p = 0.012) during VTc (SI = 1.07 [0.14]) compared with VTi (SI = 0.93 [0.18]). This study indicates that body fat percentage influences the magnitude of lung, chest wall, and total respiratory system elastance and resistance, as well as functional residual capacity. Further, these results indicate that obese dogs have extensive areas of hypoaerated lungs, especially in caudodorsal regions. Finally, lung strain and airway driving pressure, surrogates of lung deformation, are higher during VTc than during VTi, suggesting that in obese anesthetized dogs, ventilation protocols based on IBW may be advantageous.

Waistline to the gumline: Relationship between obesity and periodontal disease-biological and management considerations

Obesity is a pandemic and periodontitis is the sixth most prevalent disease in the world. These two noncommunicable diseases share several risk determinants. Epidemiologic evidence from the last 2 decades has established an increase in periodontitis prevalence in obese and overweight individuals. Biologic mechanisms potentially linking obesity and periodontal disease are adiposity-associated hyperinflammation, microbial dysbiosis, altered immune response, specific genetic polymorphisms, and increased stress. However, because of the lack of longitudinal interventional studies and randomized clinical trials, there is insufficient evidence to determine the cause-effect relationship between these two diseases. Despite this, the negative impact of obesity on oral health is well established. Several logistic and physiologic complications are associated with treating obese patients in a dental setting, and it requires an interprofessional team approach. Oral health care professionals need to be aware of the specific management considerations while rendering for this cohort, including modified practice facility and equipment, tailored supportive periodontal therapy, and heightened precaution during conscious sedation and surgical procedures.

Impact of obesity and ovariectomy on respiratory function in female mice

Obesity and the corresponding variations in female sex hormones are associated with severe lung disease. We determined the potential effects of obesity and sex hormones in female mice by investigating changes in lung structure and respiratory function in an obesity model induced by postnatal overnutrition. Obese female mice exhibited pronounced weight gain, abdominal fat accumulation and collagen type I deposition in the airways. However, neither elastic tissue nor estrogen receptors-α/-β were affected in obese female mice after ovariectomy or sham-operated mice. Bronchoconstriction in response to methacholine challenge in obese sham-operated mice was higher than in the obese group after ovariectomy. Our results suggest that the coexistence of obesity and ovariectomy impacted on respiratory system and airway resistance (attenuates bronchoconstriction after methacholine), on collagen I deposition and on airway estrogen β-receptors of mice.

Advanced endoscopic gastrointestinal techniques for the bariatric patient: implications for the anesthesia provider

PURPOSE OF REVIEW

The incidence of obesity and the use of endoscopy have risen concurrently throughout the 21st century. Bariatric patients may present to the endoscopy suite for primary treatments as well as preoperatively and postoperatively from bariatric surgery. However, over the past 10 years, endoscopic bariatric and metabolic therapies (EBMTs) have emerged as viable alternatives to more invasive surgical approaches for weight loss.

RECENT FINDINGS

The United States Food and Drug Administration (FDA) has approved several different gastric EBMTs including aspiration therapy, intragastric balloons, and endoscopic suturing. Other small intestine EBMTs including duodenal mucosal resurfacing, endoluminal magnetic partial jejunal diversion, and Duodenal-Jejunal Bypass Liner are not yet FDA approved, but are actively being investigated.

SUMMARY

Obesity causes anatomic and physiologic changes to every aspect of the human body. All EBMTs have specific nuances with important implications for the anesthesiologist. By considering both patient and procedural factors, the anesthesiologist will be able to perform a safe and effective anesthetic.

Weaning patients with obesity from ventilatory support

PURPOSE OF REVIEW

Obesity prevalence is increasing in most countries in the world. In the United States, 42% of the population is obese (body mass index (BMI) > 30) and 9.2% is obese class III (BMI > 40). One of the greatest challenges in critically ill patients with obesity is the optimization of mechanical ventilation. The goal of this review is to describe respiratory physiologic changes in patients with obesity and discuss possible mechanical ventilation strategies to improve respiratory function.

RECENT FINDINGS

Individualized mechanical ventilation based on respiratory physiology after a decremental positive end-expiratory pressure (PEEP) trial improves oxygenation and respiratory mechanics. In a recent study, mortality of patients with respiratory failure and obesity was reduced by about 50% when mechanical ventilation was associated with the use of esophageal manometry and electrical impedance tomography (EIT).

SUMMARY

Obesity greatly alters the respiratory system mechanics causing atelectasis and prolonged duration of mechanical ventilation. At present, novel strategies to ventilate patients with obesity based on individual respiratory physiology showed to be superior to those based on standard universal tables of mechanical ventilation. Esophageal manometry and EIT are essential tools to systematically assess respiratory system mechanics, safely adjust relatively high levels of PEEP, and improve chances for successful weaning.

COVID's Razor: RAS Imbalance, the Common Denominator Across Disparate, Unexpected Aspects of COVID-19

A modern iteration of Occam's Razor posits that "the simplest explanation is usually correct." Coronavirus Disease 2019 involves widespread organ damage and uneven mortality demographics, deemed unexpected from what was originally thought to be "a straightforward respiratory virus." The simplest explanation is that both the expected and unexpected aspects of COVID-19 share a common mechanism. Silent hypoxia, atypical acute respiratory distress syndrome (ARDS), stroke, olfactory loss, myocarditis, and increased mortality rates in the elderly, in men, in African-Americans, and in patients with obesity, diabetes, and cancer-all bear the fingerprints of the renin-angiotensin system (RAS) imbalance, suggesting that RAS is the common culprit. This article examines what RAS is and how it works, then from that baseline, the article presents the evidence suggesting RAS involvement in the disparate manifestations of COVID-19. Understanding the deeper workings of RAS helps one make sense of severe COVID-19. In addition, recognizing the role of RAS imbalance suggests potential routes to mitigate COVID-19 severity.