Respiratory management of the obese patient undergoing surgery

Ultrastructural changes of lung tissue under conditions of experimental obesity and smoking

Obesity can cause respiratory disorders inflicted by adipose tissue accumulation and the numerous cytokines adipocytes produce. Smoking is, first of all, associated with a wide range of lung diseases characterized by diffuse changes in the lung tissue and a decrease in the respiratory volume of the lungs. The study aimed to investigate the ultrastructural changes in the lungs of sexually mature male rats under conditions of experimental obesity and smoking. The total sample of experimental animals consisted of 120 rats, divided into four groups: the control group (n=30) - conditionally healthy rats fed on a standard diet; a group of rats subjected to isolated exposure to tobacco smoke (n=30); a group of experimentally obese rats (n=30) and a group of experimentally obese rats simultaneously exposed to tobacco smoke (n=30) - feeding using a high-fat diet with exposure to a chamber with tobacco smoke. The revealed ultrastructural features of the lungs in the group of rats with experimental obesity and the group of rats with experimental obesity that were simultaneously exposed to tobacco smoke did not differ qualitatively, which indicates that pathological changes in the ultrastructure of the lung tissue developed regardless of the presence or absence of a direct damaging effect on the lung tissue of passive smoking.

The Impact of Laparoscopic Intraperitoneal Instillation of Ropivacaine in Enhancing Respiratory Recovery and Reducing Acute Postoperative Pain in Laparoscopic Sleeve Gastrectomy: a Double-Blinded Randomised Control; RELiEVE Trial

PURPOSE

Laparoscopic intraperitoneal instillation of local anaesthetic in bariatric surgery proven to reduce postoperative pain. Limited data are available regarding the use of instillation ropivacaine and its impact on the recovery of respiratory effort. This study aims to evaluate the efficacy of laparoscopic intraperitoneal instillation of ropivacaine in reducing acute postoperative pain and enhancing the recovery of respiratory effort in laparoscopic sleeve gastrectomy.

MATERIALS AND METHODS

This double-blinded RCT enrolled 110 patients who underwent laparoscopic sleeve gastrectomy at Hospital Canselor Tuanku Muhriz UKM from November 2020 to May 2021. Any patients with previous abdominal surgery, chronic kidney disease, or liver disease were excluded. The patients were randomised into two groups: (i) the IPLA group which received ropivacaine intraperitoneal instillation at the dissected left crus and (ii) the placebo group (sterile water instillation). Perioperative analgesia was standardised. The first 24-h postoperative pain was assessed using a VAS. The respiratory effort was assessed using incentive spirometry simultaneously.

RESULTS

Total of 110 patients were recruited. The VAS score was lower with an enhanced recovery of respiratory effort in the local anaesthetic group compared to the placebo group (P < 0.05) within the first 24 h postoperatively. In addition, the placebo group required additional postoperative analgesia (P < 0.05). No side effects were reported with the use of intraperitoneal instillation of ropivacaine.

CONCLUSION

The use of intraperitoneal instillation of ropivacaine in laparoscopic sleeve gastrectomy is recommended as it is safe, effectively reduces acute postoperative pain, and enhances the recovery of respiratory effort postoperatively.

Comprehensive Review of Anesthetic Evaluation and Management in Obese Female Patients Undergoing In Vitro Fertilization

Obesity has become a global health epidemic with profound implications for various medical specialties, including reproductive medicine. This comprehensive review focuses on the anesthetic evaluation and management of obese patients undergoing in vitro fertilization (IVF) procedures. Obesity, as defined by BMI, is associated with infertility and poses unique challenges for anesthetic care. The review also addresses the timing of anesthesia concerning IVF procedures, the impact of obesity on IVF success rates, and the importance of emotional and psychological support for obese patients undergoing IVF. Challenges and future directions in the field are highlighted, focusing on ongoing research, emerging technologies, and the role of multidisciplinary teams in managing these complex cases. In conclusion, this review underscores the critical role of tailored anesthesia and perioperative care in optimizing outcomes for obese patients undergoing IVF. It provides valuable insights for anesthetic providers, reproductive specialists, and healthcare teams, emphasizing the need for a patient-centered approach to address the unique challenges posed by obesity in the context of assisted reproductive technology.

Nocturnal Hypoventilation in the Patients Submitted to Thoracic Surgery

Introduction

Nocturnal hypoventilation may occur due to obesity, concomitant chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and/or the use of narcotic analgesics. The aim of the study was to evaluate the risk and severity of nocturnal hypoventilation as assessed by transcutaneous continuous capnography in the patients submitted to thoracic surgery.

Materials and Methods

The material of the study consisted of 45 obese (BMI 34.8 ± 3.7 kg/m2) and 23 nonobese (25.5 ± 3.6 kg/m2) patients, who underwent thoracic surgery because of malignant (57 patients) and nonmalignant tumors. All the patients received routine analgesic treatment after surgery including intravenous morphine sulfate. Overnight transcutaneous measurements of CO2 partial pressure (tcpCO2) were performed before and after surgery in search of nocturnal hypoventilation, i.e., the periods lasting at least 10 minutes with tcpCO2 above 55 mmHg.

Results

Nocturnal hypoventilation during the first night after thoracic surgery was detected in 10 patients (15%), all obese, three of them with COPD, four with high suspicion of moderate-to-severe OSA syndrome, and one with chronic daytime hypercapnia. In the patients with nocturnal hypoventilation, the mean tcpCO2 was 53.4 ± 6.1 mmHg, maximal tcpCO2 was 59.9 ± 8.4 mmHg, and minimal tcpCO2 was 46.4 ± 6.7 mmHg during the first night after surgery. In these patients, there were higher values of minimal, mean, and maximal tcpCO2 in the preoperative period. Nocturnal hypoventilation in the postoperative period did not influence the duration of hospitalization. Among 12 patients with primary lung cancer who died during the first two years of observation, there were 11 patients without nocturnal hypoventilation in the early postoperative period.

Conclusion

Nocturnal hypoventilation may occur in the patients after thoracic surgery, especially in obese patients with bronchial obstruction, obstructive sleep apnea, or chronic daytime hypercapnia, and does not influence the duration of hospitalization.

Perioperative use of ketamine infusion versus dexmedetomidine infusion for analgesia in obese patients undergoing bariatric surgery: a double-blinded three-armed randomized controlled trial

BACKGROUND

Bariatric surgery depends on the development of novel anesthetic techniques to reduce the incidence of complications and improve postoperative outcomes. Ketamine and dexmedetomidine have been used for perioperative analgesia and we hypothesized that they would decrease postoperative morphine requirements. The objective of this trial is to study whether choice of ketamine or dexmedetomidine infusion would affect postoperative total morphine consumption.

METHODS

Ninety patients were equally randomized into three groups. The ketamine group received a bolus dose (0.3 mg/kg) of ketamine over 10 min, followed by an infusion of the same drug (0.3 mg/kg/h). The dexmedetomidine group received a bolus dose (0.5 mcg/kg) of dexmedetomidine over 10 min, followed by an infusion of this drug (0.5 mg/kg/h). The control group received a saline infusion. All infusions were given till 10 min before the end of surgeries. Intraoperative fentanyl was given when patient developed hypertension and tachycardia despite adequate anesthesia and muscle relaxation. Postoperative pain was managed by a rescue dose of 4 mg of IV morphine, with a minimum interval of 6 h between morphine doses if the numerical rating scale (NRS) score was ≥ 4. The primary outcome was the total morphine dose, and the secondary outcomes were intraoperative fentanyl requirement, time to extubation, postoperative nausea and vomiting (PONV), NRS scores, and modified observer's agitation/sedation scale (MOASS) scores.

RESULTS

Compared with ketamine, dexmedetomidine decreased the need for fentanyl intraoperatively (160 ± 42 µg), shortened the time to extubation (3 ± 1 min), and improved MOASS and PONV scores. In turn, ketamine decreased postoperative NRS scores and the need for morphine (3 ± 3 mg).

CONCLUSIONS

Dexmedetomidine treatment was associated with lower fentanyl doses, a shorter time to extubation, and better MOASS and PONV scores. Ketamine treatment was associated with significantly lower NRS scores and morphine doses. These results indicated that dexmedetomidine effectively decreased intraoperative fentanyl requirement and the time to extubation, while ketamine decreased the need for morphine.

TRIAL REGISTRATION

This trail was registered on the clinicaltrials.gov registry (NCT04576975) on October 6, 2020.

Effect of Intraoperative Lung Recruitment and Transversus Abdominis Plane Block in Laparoscopic Bariatric Surgery on Postoperative Lung Functions: A Randomized Controlled Study

Background

Morbid obesity may cause a restrictive condition. General anesthesia (GA) and supine posture both decrease lung capacity and functional residual capacity (FRC), altering the ventilation/perfusion ratio and raising the pulmonary shunt.

Objectives

To evaluate the impact of recruitment maneuver (RM) and transversus abdominis plane (TAP) block performed during laparoscopic bariatric surgery on spirometry, oxygenation, opioid requirements, and pain score assessed after surgery.

Methods

This pilot prospective randomized controlled study included 80 patients scheduled for elective laparoscopic bariatric surgeries (e.g., laparoscopic sleeve gastrectomy and laparoscopic gastric bypass) under GA. Patients were divided into four equal groups. All patients received a standardized postoperative analgesia regimen. Group I (control group), group II received TAP block after intubation and before surgical incision, group III received RM after intubation and after pneumoperitoneal insufflation, and group IV received RM after intubation and after pneumoperitoneal exsufflation and TAP block after intubation and before surgical incision.

Results

Forced vital capacity (FVC) and forced expiratory volume (FEV1) were significantly higher after group IV operation than in other groups. Intraoperative PaO2 and PaO2/FiO2 were significantly higher in groups III and IV compared to other groups. The numerical rating scale (NRS) at 1, 2, 4, 6, and 12h was significantly decreased in groups II and IV compared to other groups. Morphine consumption was significantly lower in groups II and IV compared to other groups.

Conclusions

TAP block combined with RM had better postoperative pulmonary function tests. Intraoperative oxygenation was higher in RM.

Obesity Indices and Ventilatory Function Responses to High-Level Laser Therapy in Subjects with Abdominal Obesity

Objective: The aim of this study is to investigate the effectiveness of pulsed Nd:YAG high-intensity laser therapy (HILT) on body weight (Wt), body-mass index (BMI), waist circumference (WC), forced vital capacity (FVC), and forced expiratory volume in 1 sec (FEV1) in young adults with abdominal obesity (AO). Materials and methods: Thirty-seven young adult males (age 19-25 years) with BMI >30 kg/m² and WC >102 cm participated in this 12-week, randomized controlled study and were randomly allocated into either Group I [received pulsed Nd:YAG HILT plus moderate-intensity aerobic exercise training (AET) program] or Group II (received placebo pulsed Nd:YAG HILT plus the same AET program). The variables were evaluated pre- and poststudy. Results: Poststudy mean values and percentages of changes were calculated for Wt [83.7 ± 6.58 kg (-6.14%) and 88.71 ± 5.09 kg (-4.29%)], BMI [29.27 ± 1.06 kg/m² (-6.14%) and 30.09 ± 1.23 kg/m² (-4.24%)], WC [105.44 ± 5.84 cm (-3.78%) and 109.42 ± 4.9 cm (-1.74%)], FVC [4.79 ± 0.4 L (+13.6%) and 4.39 ± 0.66 L (+5.89%)], and FEV1 [4.04 ± 0.22 L (+16.4%) and 3.82 ± 0.39 L (+8.8%)] for Group I and Group II, respectively. Between groups, there were significant differences in mean values of Wt (p = 0.014), BMI (p = 0.04), WC (p = 0.03), FVC (p = 0.03), and FEV1 (p = 0.04) at the end of the study, but in favor of Group I. Conclusions: Utilizing the pulsed Nd:YAG HILT as an adjunctive therapeutic modality proved to be effective in improving the anthropometric indices and ventilatory functions in subjects with AO.

A review on the anesthetic management of obese patients undergoing surgery

There has been an observed increase in theprevalence of obesity over the past few decades. The prevalence of anesthesiology related complications is also observed more frequently in obese patients as compared to patients that are not obese. Due to the increased complications that accompany obesity, obese patients are now more often requiring surgical interventions. Therefore, it is important that anesthesiologists be aware of this development and is equipped to manage these patients effectively and appropriately. As a result, this review highlights the effective management of obese patients undergoing surgery focusing on the preoperative, perioperative and postoperative care of these patients.

Impact of 30° Reserve Trendelenburg Position on Lung Function in Morbidly Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy

Background

This study aimed to evaluate the impact of patients' positioning before and after intubation with mechanical ventilation, and after extubation on the lung function and blood oxygenation of patients with morbid obesity, who had a laparoscopic sleeve gastrectomy.

Methods

Patients with morbid obesity (BMI ≥ 30 kg/m², ASA I – II grade) who underwent laparoscopic sleeve gastrectomy at our hospital from June 2018 to January 2019 were enrolled in this prospective study. Before intubation, after intubation with mechanical ventilation, and after extubation, arterial blood was collected for blood oxygenation and gas analysis after posturing the patients at supine position or 30° reverse Trendelenburg position (30°-RTP).

Results

A total of 15 patients with morbid obesity were enrolled in this self-compared study. Pulmonary shunt (Qs/Qt) after extubation was significantly lower at 30°-RTP (18.82 ± 3.60%) compared to that at supine position (17.13 ± 3.10%, p < 0.01). Patients' static lung compliance (Cstat), during mechanical ventilation, was significantly improved at 30°-RTP (36.8 ± 6.7) compared to that of those in a supine position (33.8 ± 7.3, p < 0.05). The PaO₂ and oxygen index (OI) before and after intubation with mechanical ventilation were significantly higher at 30°-RTP compared to that at supine position, and in contrast, the P_A−aO₂ before and after intubation with mechanical ventilation was significantly reduced at 30°-RTP compared to that at supine position.

Conclusion

During and after laparoscopic sleeve gastrectomy, patients with morbid obesity had improved lung function, reduced pulmonary shunt, reduced P_A−aO₂ difference, and increased PaO₂ and oxygen index at 30°-RTP compared to that supine position.

Characteristics of Obese Patients with Acute Hypercapnia Respiratory Failure Admitted in the Department of Pneumology: An Observational Study of a North African Population

BACKGROUND

Acute hypercapnic respiratory failure (AHRF) is a common life-threatening event in patients with obesity hypoventilation syndrome (OHS).

OBJECTIVES

To study the clinical pattern, noninvasive ventilatory support, as well as the short- and long-term outcomes of patients with OHS admitted in a ward because of AHRF.

METHODS

We conducted a retrospective cohort study including all adults with OHS aged ≥ 18 - year - old, admitted in a 90-bed-ward for AHRF.

RESULTS

A total of 44 patients were included. Fifteen (34.1%) and 29 (65.9%) patients were diagnosed with malignant OHS (mOHS) and nonmalignant OHS (non-mOHS), respectively, while 36 (81.8%) had coexisting obstructive sleep apnea hypopnea syndrome (OSAHS). Patients with mOHS had a significantly higher rate of heart failure (100% vs. 31%; p < 0.001), chronic renal insufficiency (CRI) (73.3% vs. 41.4%; p = 0.04), and dyslipidemia (66.7% vs. 34.5%; p = 0.04) than those with non-mOHS. The mean forced vital capacity (FVC) in our patients was of 59.5% ± 18.5 of the predicted value, lower than what is usually reported in stable patients with OHS. At hospital admission, more than two-thirds (n = 34, 77.3%) were misdiagnosed as having asthma exacerbation (n = 4, 4.9.1%), chronic obstructive pulmonary disease (COPD) exacerbation (n = 12, 27.3%) and/or heart failure (n = 29, 65.9%). Acute pulmonary oedema (ACPE) (n = 16, 36.4%) and acute viral bronchitis (n = 12, 27.3%) were the main identified causal factors, while no cause could be determined in 5 (11.4%) patients. Noninvasive positive pressure ventilation (NIPPV) using bilevel positive airway pressure (BIPAP) was very highly effective to treat AHRF, with only 2.27% of patients failing the modality. Median overall duration of ventilation was 9 hours per day (1.3-20) and was significantly longer in patients with mOHS than in those with non-mOHS (10 [6-18] vs. 8 [1.3-20], respectively; p = 0.01). Forty two of the forty-three patients discharged alive were treated with BIPAP or continuous positive airway pressure (CPAP) in 26 and 16 patients, respectively. The probability of survival was 90% at 12 months, while the probability of readmission for a new episode of AHRF was 56% at 6 months and 22% at 12 months, respectively.

CONCLUSION

AHRF in OHS patients is a life-threatening event which can be successfully and safely treated with BIPAP, with a low long-term mortality even in patients with mOHS.

Transpulmonary Pressure-Guided Lung-Protective Ventilation Improves Pulmonary Mechanics and Oxygenation Among Obese Subjects on Mechanical Ventilation

BACKGROUND

Transpulmonary pressure (P_L) is used to assess pulmonary mechanics and guide lung-protective mechanical ventilation (LPV). P_L is recommended to individualize LPV settings for patients with high pleural pressures and hypoxemia. We aimed to determine whether P_L-guided LPV settings, pulmonary mechanics, and oxygenation improve and differ from non-P_L-guided LPV among obese patients after 24 h on mechanical ventilation. Secondary outcomes included classification of hypoxemia severity, count of ventilator-free days, ICU length of stay, and overall ICU mortality.

METHODS

This is a retrospective analysis of data. Ventilator settings, pulmonary mechanics, and oxygenation were recorded on the initial day of P_L measurement and 24 h later. P_L-guided LPV targeted inspiratory P_L < 20 cm H₂O and expiratory P_L of 0-6 cm H₂O. Comparisons were made to repeat measurements.

RESULTS

Twenty subjects (13 male) with median age of 49 y, body mass index 47.5 kg/m², and SOFA score of 8 were included in our analysis. Fourteen subjects received care in a medical ICU. P_L measurement occurred 16 h after initiating non-P_L-guided LPV. P_L-guided LPV resulted in higher median PEEP (14 vs 18 cm H₂O, P = .009), expiratory P_L (-3 vs 1 cm H₂O, P = .02), respiratory system compliance (30.7 vs 44.6 mL/cm H₂O, P = .001), and [Formula: see text] (156 vs 240 mm Hg, P = .002) at 24 h. P_L-guided LPV resulted in lower [Formula: see text] (0.53 vs 0.33, P < .001) and lower P_L driving pressure (10 vs 6 cm H₂O, P = .001). Tidal volume (420 vs 435 mL, P = .64) and inspiratory P_L (7 vs 7 cm H₂O, P = .90) were similar. Subjects had a median of 7 ventilator-free days, and median ICU length of stay was 14 d. Three of 20 subjects died within 28 d after ICU admission.

CONCLUSIONS

P_L-guided LPV resulted in higher PEEP, lower [Formula: see text], improved pulmonary mechanics, and greater oxygenation when compared to non-P_L-guided LPV settings in adult obese subjects.

The association between residual neuromuscular blockade (RNMB) and critical respiratory events: a prospective cohort study

Background

Inadequate neuromuscular recovery might impair pulmonary function among adult patients who undergo general anaesthesia and might thus contribute to critical respiratory events in the post-anaesthesia care unit (PACU). The pilot study aims to understand the baseline incidence of residual neuromuscular blockade (RNMB) and postoperative critical respiratory events (CREs), which are described in a modified Murphy’s criteria in the PACU.

Method

This is a prospective cohort study from January to March 2017 from a tertiary hospital in Saudi Arabia with thirty adult patients over 18 years old scheduled for elective surgery under general anaesthesia with neuromuscular blocking drugs (NMBDs) who were enrolled in the study. The Mann-Whitney U tests, chi-square tests and independent-samples T tests were used. The train-of-four (TOF) ratios were measured upon arrival in the PACU by using acceleromyography with TOF-Scan. Subjects’ demographics, perioperative data and the occurrence of postoperative CREs in the PACU were recorded.

Results

Twenty-six (86.7%) patients out of thirty in the study have received rocuronium as NMBDs whilst neostigmine as a reversal drug with only 23 (76.7%). The incidence of RNMB (TOF ratio < 0.9) was in 16 patients (53.3%). The incidence of RNMB was significantly higher in female patients (p = 0.033), in patients who had not undergone quantitative neuromuscular monitoring before extubation (p = 0.046) and in patients with a shorter duration of surgery (p = 0.001). Postoperative CREs occurred in twenty patients (66.7%), and there were significantly more of these CREs among patients with RNMB (p = 0.001). In addition, a statistically significant difference was observed in the occurrence of CREs according to body mass index (p = 0.047).

Conclusion

This research showed that RNMB is a significant contributing factor to the development of critical respiratory events during PACU stay. Therefore, routine quantitative neuromuscular monitoring is recommended to reduce the incidence of RNMB.

Endoscopic gastroplasty: an effective solution in a high-risk patient with morbid obesity

A 61-year-old man was referred to the bariatric endoscopy unit for the management of morbid obesity (BMI 47 kg/m²). He had multiple obesity-related medical comorbidities. His weight gain started 8 years after suffering smoke inhalation syndrome following an industrial accident. He sustained permanent lung parenchymal injury resulting in impaired pulmonary function. His mobility was restricted to a wheelchair and was dependent on long term oxygen therapy. He tried diet and lifestyle intervention but could not achieve significant weight loss. He was referred for bariatric surgery but was declined because of substantial comorbidities, poor pulmonary function, anesthetic risk (ASA Class 4), and risk of complications. After depleting all of his options, he sought us for endoscopic therapy. Following a successful collaboration with the anesthetist, endocrinologist, and nutritionist, we performed an endoscopic gastroplasty using the modified primary obesity surgery endoluminal procedure (POSE-2) and reduced the gastric volume. He recovered immediately without complications and achieved significant weight loss at 10 months (41 kg). He is now able to walk, the oxygen requirements have decreased, and the comorbidities have significantly improved.

The impact of body mass index, central obesity and physical activity on lung function: results of the EpiHealth study

Study objectives

Obesity is often associated with lower lung function; however, the interaction of lung function with central obesity and physical inactivity is less clear. As such, we investigated the effect on lung function of body size (body mass index (BMI)), central obesity (waist circumference (WC)) and self-reported physical activity.

Methods

Lung function, height, weight and WC were measured in 22 743 participants (12 791 women), aged 45–75 years, from the EpiHealth cohort study. Physical activity, gender and educational level were assessed using a questionnaire.

Results

Obesity, central obesity and physical inactivity were all associated with lower forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC). However, in participants without central obesity there was an increase in both FEV₁ and FVC by BMI (% predicted FVC increasing from median 98%, interquartile range (IQR) 89–110% in underweight participants (BMI <20) to 103%, IQR 94–113% in obese participants (BMI ≥30)). In contrast, there was a decrease in % predicted FVC in participants with central obesity (from 98%, IQR 89–109% in the normal weight group to 95%, IQR 85–105% in the obese weight group). We further found a negative association between physical activity and lung function among those with low and high levels of physical activity (% predicted FEV₁ 97%, IQR 86–107% versus 103%, IQR 94–113%, respectively and % predicted FVC 96%, IQR 85–106% versus 103%, IQR 94–113%, respectively). All results remained when calculated by z-scores.

Conclusions

The association between BMI and lung function is dependent on the presence of central obesity. Independent of obesity, there is an association between physical activity and lung function.

BMI and central obesity are related to lung function in the middle-aged and elderly. BMI association with lung function is dependent on the presence of central obesity, while the association of physical activity and lung function is independent of obesity.https://bit.ly/3eQl86C

How to ventilate obese patients in the ICU

Obesity is an important risk factor for major complications, morbidity and mortality related to intubation procedures and ventilation in the intensive care unit (ICU). The fall in functional residual capacity promotes airway closure and atelectasis formation. This narrative review presents the impact of obesity on the respiratory system and the key points to optimize airway management, noninvasive and invasive mechanical ventilation in ICU patients with obesity. Non-invasive strategies should first optimize body position with reverse Trendelenburg position or sitting position. Noninvasive ventilation (NIV) is considered as the first-line therapy in patients with obesity having a postoperative acute respiratory failure. Positive pressure pre-oxygenation before the intubation procedure is the method of reference. The use of videolaryngoscopy has to be considered by adequately trained intensivists, especially in patients with several risk factors. Regarding mechanical ventilation in patients with and without acute respiratory distress syndrome (ARDS), low tidal volume (6 ml/kg of predicted body weight) and moderate to high positive end-expiratory pressure (PEEP), with careful recruitment maneuver in selected patients, are advised. Prone positioning is a therapeutic choice in severe ARDS patients with obesity. Prophylactic NIV should be considered after extubation to prevent re-intubation. If obesity increases mortality and risk of ICU admission in the overall population, the impact of obesity on ICU mortality is less clear and several confounding factors have to be taken into account regarding the “obesity ICU paradox”.

The Potential Role of Lung-Protective Ventilation in Preventing Postoperative Delirium in Elderly Patients Undergoing Prone Spinal Surgery: A Preliminary Study

Background

Postoperative delirium (POD) is a frequent complication in elderly patients, usually occurring within a few days after surgery. This study investigated the effect of lung-protective ventilation (LPV) on POD in elderly patients undergoing spinal surgery and the mechanism by which LPV suppresses POD.

Material/Methods

Seventy-one patients aged ≥65 years were randomized to receive LPV or conventional mechanical ventilation (MV), consisting of intermittent positive pressure ventilation following induction of anesthesia. The tidal volume in patients who received MV was 8 ml/kg predicted body weight (PBW), and the ventilation frequency was 12 times/min. The tidal volume in patients who received LPV was 6 ml/kg PBW, the positive end-expiratory pressure was 5 cmH₂O, and the ventilation frequency was 15 times/min, with a lung recruitment maneuver performed every 30 min. Blood samples were collected immediately before anesthesia induction (T₀), 10 min (T₁) and 60 min (T₂) after turning over, immediately after the operation (T₃), and 15 min after extubation (T₄) for blood gas analysis. Simultaneous cerebral oxygen saturation (rSO₂) and cerebral desaturation were recorded. Preoperative and postoperative serum concentrations of interleukin (IL)-6, IL-10 and glial fibrillary acidic protein (GFAP) were measured by ELISA. POD was assessed by nursing delirium screening score.

Results

Compared with the MV group, pH was lower and PaCO₂ higher in the LPV group at T₂. In addition PaO₂, SaO₂, and PaO₂/FiO₂ were higher at T₁, and T₄, and rSO₂ was higher at T₃, and T₄ in the LPV than in the MV group (P<0.05 each). Postoperative serum GFAP and IL-6 were lower and IL-10 higher in the LPV group. The incidences of cerebral desaturation and POD were significantly lower in the LPV group (P<0.05).

Conclusions

LPV may reduce POD in elderly patients undergoing spinal surgery by inhibiting inflammation and improving cerebral oxygen metabolism.

Recognizing Risks and Optimizing Perioperative Care to Reduce Respiratory Complications in the Pediatric Patient

There have been significant advancements in the safe delivery of anesthesia as well as improvements in surgical technique; however, the perioperative period can still be high risk for the pediatric patient. Perioperative respiratory complications (PRCs) are some of the most common critical events that can occur in pediatric surgical patients and they can lead to increased length of hospitalization, worsened patient outcomes, and higher hospital and postoperative costs. It is important to determine the various factors that put pediatric patients at increased risk of PRCs. This will allow for more detailed and accurate informed consent, optimized perioperative management strategy, improved allocation of clinical resources, and, hopefully, better patient experience. There are only a few risk prediction models/scoring tools developed for and validated in the pediatric patient population, but they have been useful in helping identify the key factors associated with a high likelihood of developing PRCs. Some of these factors are patient factors, while others are procedure-related factors. Some of these factors may be modified such that the patient’s clinical status is optimized preoperatively to decrease the risk of PRCs occurring perioperatively. Fore knowledge of the factors that are not able to be modified can help guide allocation of perioperative clinical resources such that the negative impact of these non-modifiable factors is buffered. Additional training in pediatric anesthesia or focused expertise in pediatric airway management, vascular access and management of massive hemorrhage should be considered for the perioperative management of the less than 3 age group. Intraoperative ventilation strategy plays a key role in determining respiratory outcomes for both adult and pediatric surgical patients. Key components of lung protective mechanical ventilation strategy such as low tidal volume and moderate PEEP used in the management of acute respiratory distress syndrome (ARDS) in pediatric intensive care units have been adopted in pediatric operating rooms. Adequate post-operative analgesia that balances pain control with appropriate mental status and respiratory drive is important in reducing PRCs.

Obesity associated with increased postoperative pulmonary complications and mortality after trauma laparotomy

Background

Patient-related risk factors for the development of postoperative pulmonary complications (PPCs) include age ≥ 60-years, congestive heart failure, hypoalbuminemia and smoking. The effect of obesity is unclear and has not been shown to independently increase the likelihood of PPCs in trauma patients undergoing trauma laparotomy. We hypothesized the likelihood of mortality and PPCs would increase as body mass index (BMI) increases in trauma patients undergoing trauma laparotomy.

Methods

The Trauma Quality Improvement Program (2010–2016) was queried to identify trauma patients ≥ 18-years-old undergoing trauma laparotomy within 6-h of presentation. A multivariable logistic regression analysis was used to determine the likelihood of PPCs and mortality when stratified by BMI.

Results

From 8,330 patients, 2,810 (33.7%) were overweight (25–29.9 kg/m²), 1444 (17.3%) obese (30–34.9 kg/m²), 580 (7.0%) severely obese (35–39.9 kg/m²), and 401 (4.8%) morbidly obese (≥ 40 kg/m²). After adjusting for covariates including age, injury severity score, chronic obstructive pulmonary disease, smoking, and rib/lung injury, the likelihood of PPCs increased with increasing BMI: overweight (OR = 1.37, CI 1.07–1.74, p = 0.012), obese (OR = 1.44, CI 1.08–1.92, p = 0.014), severely obese (OR = 2.20, CI 1.55–3.14, p < 0.001), morbidly obese (OR = 2.42, CI 1.67–3.51, p < 0.001), compared to those with normal BMI. In addition, the adjusted likelihood of mortality increased for the morbidly obese (OR = 2.60, CI 1.78–3.80, p < 0.001) compared to those with normal BMI.

Conclusion

Obese trauma patients undergoing emergent trauma laparotomy have a high likelihood for both PPCs and mortality, with morbidly obese trauma patients having the highest likelihood for both. This suggests obesity should be accounted for in risk prediction models of trauma patients undergoing laparotomy.

Electronic supplementary material

The online version of this article (10.1007/s00068-020-01329-w) contains supplementary material, which is available to authorized users.

Relationship between metabolic syndrome and hypercapnia among obese patients with sleep apnea

BACKGROUND

In the obese patient population, some patients have severe obstructive sleep apnea (OSA) with daytime hypoventilation. Such patients are generally identified on the basis of the presence or absence of daytime hypercapnia, and the condition is called obesity hypoventilation syndrome. However, mechanisms for such daytime hypoventilation remain unclear.

AIM

To investigate metabolic syndrome and daytime hypercapnia association based on hypercapnia prevalence in obese OSA patients in a nested case-control study.

METHODS

Consecutive obese patients (body mass index ≥ 30 kg/m²) who underwent polysomnography due to suspected OSA were included. Among them, patients with severe OSA (apnea hypopnea index ≥ 30/h) were divided into two groups according to the presence or absence of hypercapnia during wakefulness (arterial partial pressure of carbon dioxide ≥ or < 45 Torr, respectively). The characteristics and clinical features of these two groups were compared.

RESULTS

Among 97 eligible patients, 25 patients (25.8%) had daytime hypercapnia. There were no significant differences in age, gender, body mass index, apnea-hypopnea index, and Epworth Sleepiness Scale scores between the two groups. However, patients with hypercapnia had a significantly lower arterial partial pressure of oxygen level (75.8 ± 8.2 torr vs 79.9 ± 8.7 torr, P = 0.042) and higher arterial partial pressure of carbon dioxide level (46.6 ± 2.5 torr vs 41.0 ± 2.9 torr, P < 0.001). Additionally, patients with hypercapnia were more likely to have metabolic syndrome (72.0% vs 48.6%, P = 0.043) and a higher metabolic score (the number of satisfied criteria of metabolic syndrome). In multivariate logistic regression analysis, the presence of metabolic syndrome was associated with the presence of hypercapnia (OR = 2.85, 95%CI: 1.04-7.84, P = 0.042).

CONCLUSION

Among obese patients with severe OSA, 26% of patients had hypercapnia during wakefulness. The presence of metabolic syndrome was independently correlated with the presence of daytime hypercapnia.

Incidence and Risk Factors of Pulmonary Complications after Robot-Assisted Laparoscopic Prostatectomy: A Retrospective Observational Analysis of 2208 Patients at a Large Single Center

Robot-assisted laparoscopic prostatectomy (RALP) is a minimally invasive technique for the treatment of prostate cancer. RALP requires the patient to be placed in the steep Trendelenburg position, along with pneumoperitoneum, which may increase the risk of postoperative pulmonary complications (PPCs). This large single-center retrospective study evaluated the incidence and risk factors of PPCs in 2208 patients who underwent RALP between 2014 and 2017. Patients were divided into those with (PPC group) and without (non-PPC group) PPCs. Postoperative outcomes were evaluated, and univariate and multivariate logistic regression analyses were performed to assess risk factors of PPCs. PPCs occurred in 682 patients (30.9%). Risk factors of PPCs included age (odds ratio [OR], 1.023; p = 0.001), body mass index (OR, 1.061; p = 0.001), hypoalbuminemia (OR, 1.653; p = 0.008), and positive end-expiratory pressure (PEEP) application (OR, 0.283; p < 0.001). The incidence of postoperative complications, rate of intensive care unit (ICU) admission, and duration of ICU stay were significantly greater in the PPC group than in the non-PPC group. In conclusion, the incidence of PPCs in patients who underwent RALP under pneumoperitoneum in the steep Trendelenburg position was 30.9%. Factors associated with PPCs included older age, higher body mass index, hypoalbuminemia, and lack of PEEP.

Atelectasis in Bariatric Surgery: Review Analysis and Key Practical Recommendations

Obesity is a condition that affects multiple organ systems, particularly the cardiovascular and respiratory system. In recent years, bariatric surgery has been reported to be the gold standard in the treatment of morbid obesity. Body mass index alone is insufficient to predict risks related to anaesthesia and surgery. Obesity contributes to significant postoperative atelectasis and is considered an independent risk factor for postoperative atelectasis owing to decreased functional residual capacity. The treatment and reversibility of atelectasis developed in obese patients undergoing bariatric surgery are challenging. Therefore, an optimisation of pulmonary functions before surgery, lung-sparing ventilation during the perioperative period, awareness of potential postoperative complications and knowledge about preventive measures and therapeutic approaches have become increasingly important in bariatric surgery. The aim of this review was to aid clinicians in the management of atelectasis in patients undergoing bariatric surgery during the perioperative and postoperative period.

The development and validation of the Score for the Prediction of Postoperative Respiratory Complications (SPORC-2) to predict the requirement for early postoperative tracheal re-intubation: a hospital registry study

Postoperative pulmonary complications are associated with an increase in mortality, morbidity and healthcare utilisation. The Agency for Healthcare Research and Quality recommends risk assessment for postoperative respiratory complications in patients undergoing surgery. In this hospital registry study of adult patients undergoing non-cardiac surgery between 2005 and 2017 at two independent healthcare networks, a prediction instrument for early postoperative tracheal re-intubation was developed and externally validated. This was based on the development of the Score for Prediction Of Postoperative Respiratory Complications. For predictor selection, stepwise backward logistic regression and bootstrap resampling were applied. Development and validation cohorts were represented by 90,893 patients at Partners Healthcare and 67,046 patients at Beth Israel Deaconess Medical Center, of whom 699 (0.8%) and 587 (0.9%) patients, respectively, had their tracheas re-intubated. In addition to five pre-operative predictors identified in the Score for Prediction Of Postoperative Respiratory Complications, the final model included seven additional intra-operative predictors: early post-tracheal intubation desaturation; prolonged duration of surgery; high fraction of inspired oxygen; high vasopressor dose; blood transfusion; the absence of volatile anaesthetic use; and the absence of lung-protective ventilation. The area under the receiver operating characteristic curve for the new score was significantly greater than that of the original Score for Prediction Of Postoperative Respiratory Complications (0.84 [95%CI 0.82-0.85] vs. 0.76 [95%CI 0.75-0.78], respectively; p < 0.001). This may allow clinicians to develop and implement strategies to decrease the risk of early postoperative tracheal re-intubation.

High flow nasal oxygen after bariatric surgery (OXYBAR), prophylactic post-operative high flow nasal oxygen versus conventional oxygen therapy in obese patients undergoing bariatric surgery: study protocol for a randomised controlled pilot trial

BACKGROUND

The incidence of obesity is increasing worldwide. In selected individuals, bariatric surgery may offer a means of achieving long-term weight loss, improved health, and healthcare cost reduction. Physiological changes that occur because of obesity and general anaesthesia predispose to respiratory complications following bariatric surgery. The aim of this study is to determine whether post-operative high flow nasal oxygen therapy (HFNO2) improves respiratory function and reduces the incidence of post-operative pulmonary complications (PPCs) in comparison to conventional oxygen therapy in these patients.

METHOD

The OXYBAR study is a prospective, un-blinded, single centre, randomised, controlled pilot study. Patients with body mass index (BMI) > 30 kg/m2, undergoing laparoscopic bariatric surgery, will be randomised to receive either standard low flow oxygen therapy or HFNO2 in the post-operative period. The primary outcome measure is the change in end expiratory lung impedance (∆EELI) as measured by electrical impedance tomography (EIT). Secondary outcome measures include change in tidal volume (∆Vt), partial arterial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, incidence of PPCs, hospital length of stay and measures of patient comfort.

DISCUSSION

We hypothesise that the post-operative administration of HFNO2 will increase EELI and therefore end expiratory lung volume (EELV) in obese patients. To our knowledge this is the first trial designed to assess the effects of HFNO2 on EELV in this population. We anticipate that data collected during this pilot study will inform a larger multicentre trial.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12617000694314 . Registered on 15 May 2017.

Protective effect of grape seed and skin extract against high-fat diet-induced dyshomeostasis of energetic metabolism in rat lung

BACKGROUND

Obesity is currently one of the major epidemics of this millennium and affects poeples throughout the world. It causes multiple systemic complications as it significantly interferes with respiratory function.

OBJECTIVE

We aimed in the present work to study the effect of high fat diet (HFD) on lung oxidative stress and energy metabolism alterations, as well as the putative protection afforded by grape seed and skin extract (GSSE).

METHODS

We started by characterizing the GSSE and its composition using gas chromatography coupled to mass spectrometry (GC-MS). We used a rat model of high-fat-diet and we evaluated the effect of GSSE on oxidative stress and energetic disturbances induced by HFD. We analyzed the effect of HFD on lung oxidative status by assessing lipid oxidation level, non-protein thiols (NPSH) and superoxide anion level… We also evaluated the effect of HFD on creatine kinase (CK), malate dehydrogenase (MDH) and mitochondrial complex IV.

RESULTS

HFD induced body weight gain, increased lung weight and lipid content without affecting insulinemia and dropped adiponectemia. HFD also provoked on lung oxidative stress characterized by increased carbonylation (+ 95%; p = 0.0045), decreased of NPSH (- 32%; p = 0.0291) and inhibition of antioxidant enzyme activities such as glutathione peroxidase (- 25%; p = 0.0074). HFD also altered lung intracellular mediators as superoxide anion O2¯ (+ 59%; p = 0.0027) and increased lung xanthine oxidase activity (+ 27%; p = 0.0122). HFD induced copper depletion (- 24%; p = 0.0498) and lead (- 51%: p = 0.0490) from the lung. Correlatively HFD decreased the copper associated enzyme tyrosinase (- 29%; p = 0.0500) and decreased glutamine synthetase activity (- 31%; p = 0.0027). HFD altered also lung energy metabolism by increasing CK activity (+ 22%; p = 0.0108) and decreasing MDH and mitochondrial complex IV activities (- 28%; p = 0.0120, - 31%; p = 0.0086 respectively). Importantly all these alterations were efficiently corrected with GSSE treatment.

CONCLUSION

In conclusion, GSSE has the potential to alleviate the deleterious lipotoxic effect of HFD on lung and it could find potential application in the protection against HFD-induced lung complications.

The impact of obesity on pulmonary deterioration in patients undergoing robotic-assisted laparoscopic prostatectomy

Obesity affects respiratory and hemodynamic function in anesthetized patients. The aim of this study was to evaluate the influence of the body mass index (BMI) on pulmonary changes in a permanent 45° steep Trendelenburg position (STP) during robotic-assisted laparoscopic prostatectomy (RALP). 51 patients undergoing RALP under standardized anesthesia were included. Perioperative pulmonary function and oxygenation were measured in awake patients (T₀), 20 min after the induction of anesthesia (T₁), after insufflation of the abdomen in supine position (T₂), after 30 min in STP (T₃), when controlling Santorini's plexus in STP (T₄), before awakening while supine (T₅), and after 45 min in the recovery room (T₆). Patient-specific and time-dependent factor on ventilation and predicted peak inspiratory pressure (PIP), driving pressure (P_driv) and lung compliance (LC) in a linear regression model were calculated. PIP and P_driv increased significantly after induction of capnoperitoneum (T_2-4) (p < 0.0001). In univariate mixed effects models, BMI was found to be a significant predictor for PIP and P_driv increase and LC decrease. Obese patients a BMI > 31 kg/m² reached critical PIP values ≥ 35 cmH₂O. Postoperative oxygenation represented by the PaO₂/FiO₂ ratio was significantly decreased compared to T₀ (p < 0.0001). Obesity in combination with STP and capnoperitoneum during RALP has a profound effect on pulmonary function. Increased PIP and P_driv and decreased LC are directly correlated with a high BMI. Changes in PIP, P_driv and LC during RALP may be predicted in relation to patient's BMI for consideration in the preoperative setting. Trial registration number Z-2014-0387-6. Registered on 8 July 2014.

Application of intraoperative lung-protective ventilation varies in accordance with the knowledge of anaesthesiologists: a single-Centre questionnaire study and a retrospective observational study

Background

The benefits of lung-protective ventilation (LPV) with a low tidal volume (6 mL/kg of ideal body weight [IBW]), limited plateau pressure (< 28–30 cm H₂O), and appropriate positive end-expiratory pressure (PEEP) in patients with acute respiratory distress syndrome have become apparent and it is now widely adopted in intensive care units. Recently evidence for LPV in general anaesthesia has been accumulated, but it is not yet generally applied by anaesthesiologists in the operating room.

Methods

This study investigated the perception about intraoperative LPV among 82 anaesthesiologists through a questionnaire survey and identified the differences in ventilator settings according to recognition of lung-protective ventilation. Furthermore, we investigated the changes in the trend for using this form of ventilation during general anaesthesia in the past 10 years.

Results

Anaesthesiologists who had received training in LPV were more knowledgeable about this approach. Anaesthesiologists with knowledge of the concept behind LPV strategies applied a lower tidal volume (median (IQR [range]), 8.2 (8.0–9.2 [7.1–10.3]) vs. 9.2 (9.1–10.1 [7.6–10.1]) mL/kg; p = 0.033) and used PEEP more frequently (69/72 [95.8%] vs. 5/8 [62.5%]; p = 0.012; odds ratio, 13.8 [2.19–86.9]) for laparoscopic surgery than did those without such knowledge. Anaesthesiologists who were able to answer a question related to LPV correctly (respondents who chose ‘height’ to a multiple choice question asking what variables should be considered most important in the initial setting of tidal volume) applied a lower tidal volume in cases of laparoscopic surgery and obese patients. There was an increase in the number of patients receiving LPV (V_T < 10 mL/kgIBW and PEEP ≥5 cm H₂O) between 2004 and 2014 (0/818 [0.0%] vs. 280/818 [34.2%]; p <  0.001).

Conclusions

Our study suggests that the knowledge of LPV is directly related to its implementation, and can explain the increase in LPV use in general anaesthesia. Further studies should assess the impact of using intraoperative LPV on clinical outcomes and should determine the efficacy of education on intraoperative LPV implementation.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0495-7) contains supplementary material, which is available to authorized users.

Anaesthetic Preparation of Obese Patients: Current Status on Optimal Work-up

PURPOSE OF REVIEW

With the prevalence of obesity rapidly growing, bariatric anaesthesia becomes everyday anaesthesia rather than a subspecialty. In this review, we are aiming to draw attention to this complex group of patients and their comorbidities, relevant to everyday practice for contemporary anaesthetists.

RECENT FINDINGS

We wanted to focus greatly on sleep-related breathing disorders, because preoperative screening, diagnosis and treatment of the aforementioned make a huge impact in the improvement of preoperative morbidity and mortality, including positive effects on the cardiovascular system. The overview is touching on main obesity-related comorbidities and guides the anaesthetist and associated health professionals on how to approach and manage them. A multidisciplinary approach widely used in bariatric care may be adopted in the care of obese patients in order to reduce preoperative morbidity and mortality. We advocate the early involvement of the anaesthetic team in the preoperative assessment of obese patients in order to achieve appropriate risk stratification and optimise the care.

Value of endometrial thickness assessed by transvaginal ultrasound for the prediction of endometrial cancer in patients with postmenopausal bleeding

PURPOSE

Histological confirmation of endometrial cancer by dilatation/curettage (D/C) in women with postmenopausal bleeding (PMB) can be challenging due to anesthesiological and/or surgical risks. Thus, less invasive methods for diagnostics are required to identify patients with minimal risk for endometrial cancer (EC) to avoid unnecessary surgical intervention. The objective of this single-center cohort study was to assess the diagnostic validity of transvaginal ultrasound (TVUS) measurements of endometrial thickness (ET) in patients with PMB for the detection of EC.

METHODS

A retrospective analysis of data from patients presenting between January 2005 and August 2014 at the Department of Obstetrics and Gynecology, University Hospital Ulm, Germany, with PMB and subsequent D/C was performed. Complete data with TVUS documentation of ET and histological results of tissue samples were available from 254 patients. In addition, data on age, body mass index (BMI), ASA-score, diabetes, hypertension, and hematological laboratory values (for a smaller subsample) were recorded. To identify independent risk factors, a multivariate logistic regression with endometrial cancer as binary response variable (yes/no) was performed. Diagnostic efficacy data for different ET cutoff points (≤1 to ≤26 mm) were obtained by a receiver operator characteristic (ROC) curve analysis.

RESULTS

The multivariate logistic regression revealed a significant independent predictive value for age and ET. However, none of the analyzed ET cutoff points showed optimal diagnostic validity, as all cutoff points with sensitivity rates above 90% (≤1 to ≤5 mm) had false positive rates of 70% and higher.

CONCLUSIONS

There is no ET cutoff point that provides good diagnostic accuracy and/or reliably excludes the presence of endometrial cancer in patients with PMB. Thus, our data analysis supports the actual German approach of histological evaluation of any PMB to confirm or exclude EC.

The effect of perioperative insulin treatment on cardiodepression in mild adiposity in mice

Background

While most studies focus on cardiovascular morbidity following anesthesia and surgery in excessive obesity, it is unknown whether these intraoperative cardiovascular alterations also occur in milder forms of adiposity without type 2 diabetes and if insulin is a possible treatment to improve intraoperative myocardial performance. In this experimental study we investigated whether mild adiposity without metabolic alterations is already associated with cardiometabolic dysfunction during anesthesia, mechanical ventilation and surgery and whether these myocardial alterations can be neutralized by intraoperative insulin treatment.

Methods

Mice were fed a western (WD) or control diet (CD) for 4 weeks. After metabolic profiling, mice underwent general anesthesia, mechanical ventilation and surgery. Cardiac function was determined with echocardiography and left-ventricular pressure–volume analysis. Myocardial perfusion was determined with contrast-enhanced echocardiography. WD-fed mice were subsequently treated with insulin by hyperinsulinemic euglycemic clamping followed by the same measurements of cardiac function and perfusion.

Results

Western-type diet feeding led to a 13 % increase in bodyweight, (p < 0.0001) and increased adipose tissue mass, without metabolic alterations. Despite this mild phenotype, WD-fed mice had decreased systolic and diastolic function (end-systolic elastance was 2.0 ± 0.5 versus 4.1 ± 2.4 mmHg/μL, p = 0.01 and diastolic beta was 0.07 ± 0.03 versus 0.04 ± 0.01 mmHg/μL, p = 0.02) compared to CD-fed mice. Ventriculo-arterial coupling and myocardial perfusion were decreased by 48 % (p = 0.003) and 43 % (p = 0.03) respectively. Insulin treatment in WD-fed mice improved echo-derived systolic function (fractional shortening 42 ± 5 % to 46 ± 3, p = 0.05), likely due to decreased afterload, but there was no effect on load-independent measures of systolic function or myocardial perfusion. However, there was a trend towards improved diastolic function after insulin treatment (43 % improvement, p = 0.05) in WD-fed mice.

Conclusions

Mild adiposity without metabolic alterations already affected cardiac function and perfusion during anesthesia, mechanical ventilation and surgery in mice. Intraoperative insulin may be beneficial to reduce afterload and enhance intraoperative ventricular relaxation, but not to improve ventricular contractility or myocardial perfusion.

Obesity: systemic and pulmonary complications, biochemical abnormalities, and impairment of lung function

Obesity is currently one of the major epidemics of this millennium and affects individuals throughout the world. It causes multiple systemic complications, some of which result in severe impairment of organs and tissues. These complications involve mechanical changes caused by the accumulation of adipose tissue and the numerous cytokines produced by adipocytes. Obesity also significantly interferes with respiratory function by decreasing lung volume, particularly the expiratory reserve volume and functional residual capacity. Because of the ineffectiveness of the respiratory muscles, strength and resistance may be reduced. All these factors lead to inspiratory overload, which increases respiratory effort, oxygen consumption, and respiratory energy expenditure. It is noteworthy that patterns of body fat distribution significantly influence the function of the respiratory system, likely via the direct mechanical effect of fat accumulation in the chest and abdominal regions. Weight loss caused by various types of treatment, including low-calorie diet, intragastric balloon, and bariatric surgery, significantly improves lung function and metabolic syndrome and reduces body mass index. Despite advances in the knowledge of pulmonary and systemic complications associated with obesity, longitudinal randomized studies are needed to assess the impact of weight loss on metabolic syndrome and lung function.