Decrease In Functional Residual Capacity Research Articles

Prenatal Exposure to Oxidative Potential and Lung Function in Infants and Preschool- Age Children: A Prospective Study.

Fine particulate matter () has been found to be detrimental to respiratory health of children, but few studies have examined the effects of prenatal oxidative potential (OP) on lung function in infants and preschool children. We estimated the associations of personal exposure to and OP during pregnancy on offspring objective lung function parameters and compared the strengths of associations between both exposure metrics. We used data from 356 mother-child pairs from the SEPAGES cohort. PM filters collected twice during a week were analyzed for OP, using the dithiothreitol (DTT) and the ascorbic acid (AA) assays, quantifying the exposure of each pregnant woman. Lung function was assessed with tidal breathing analysis (TBFVL) and nitrogen multiple-breath washout () test, performed at 6 wk, and airwave oscillometry (AOS) performed at 3 y. Associations of prenatal mass and OP with lung function parameters were estimated using multiple linear regressions. In neonates, an interquartile (IQR) increase in () was associated with a decrease in functional residual capacity (FRC) measured by [; 95% confidence interval (CI): , 0.15]. Associations with showed similar patterns in comparison with but of smaller magnitude. Lung clearance index (LCI) and TBFVL parameters did not show any clear association with the exposures considered. At 3 y, increased frequency-dependent resistance of the lungs () from AOS tended to be associated with higher (; 95% CI: , 0.24) and (; ; 95% CI: , 0.27) but not with (; ; 95% CI: , 0.16). Results for FRC and remained similar in OP models adjusted on . Prenatal exposure to was associated with several offspring lung function parameters over time, all related to lung volumes. https://doi.org/10.1289/EHP11155.

897: VV ECMO AFTER COMPLICATED ABDOMINAL SURGERY IN AN OBESE PATIENT: IS EARLIER BETTER?

Introduction: Aspiration pneumonia and respiratory failure following abdominal surgery are well-known complications in patients with a body mass index (BMI) over 30 kg/m2. The use of venous-venous extracorporeal membrane oxygenation (VV-ECMO) as rescue therapy has been explored in patients who develop acute respiratory failure postoperatively. This case strives to highlight the importance of early initiation of VV-ECMO to improve outcomes in obese patients. Description: A 59-year-old woman with past medical history of hypertension and morbid obesity status post laparoscopic Roux-en-y gastric bypass presented with new onset nausea, emesis, and abdominal pain. Patient was febrile, tachycardic, hypoxic, and hypotensive upon evaluation. Physical exam was significant for bibasilar coarse breath sounds, abdominal distention, and hypoactive bowel sounds. Abdominal radiography showed evidence of small bowel obstruction and chest radiography revealed massive aspiration with unilateral pleural effusion. Patient ultimately required exploratory laparotomy after failure of conservative management for unresolved bowel obstruction. The post-operative course was complicated by acute respiratory failure, which did not improve despite multiple measures. VV-ECMO was then initiated, which led to significant recovery of hemodynamics and respiratory status in three days. Discussion: Anesthetic-induced decrease in functional residual capacity, disruption of thoracoabdominal musculature during abdominal surgery, and pre-existing lung disease predispose obese patients to respiratory failure. Non-invasive approaches are limited and invasive mechanical ventilation becomes the appropriate next step to achieve improved oxygenation in this sub-set of patients. Studies show that obesity is an independent factor in improving 90-day survival when transitioned to VV-ECMO early in the clinical course. Further clinical studies are required to determine the optimal time between initiation of mechanical ventilation and transition to VV-ECMO, as well as the effect on ICU and hospital length of stay.

Особенности выбора функциональных критериев, оценивающих непосредственное влияние мануального воздействия

35 patients with bronchial asthma were examined in order to determine the optimal criteria for evaluating the effectiveness of a separate manual procedure (medical massage). It was established that changes in the respiration function after the massage procedure, according to the indicators obtained by the methods of general plethysmography and spirometry, were multidirectional. Bronchial resistance (Raw) significantly decreased, and bronchial specific conductance (Sgaw) increased (-19.50.52 and +23.93.9%, respectively; p < 0.05), with a simultaneous decrease in functional residual capacity by 8.500.98%. The subjective sensation of shortness of breath also significantly decreased (VAS= - 14.810.8%; p < 0.01). Bronchodilation response after medical massage in terms of SGaw correlated with VAS dynamics (r=0.642, p<0.05). At the same time, the traditionally determined indicators of the respiratory function decreased (PEF -12.01.8%, FEV1 = -9.65.1%), and it is interpreted as a deterioration in the respiratory function according to the generally accepted assessment. Therefore, a direct assessment of manual exposure should be based on clinical and functional indicators that reflect the targeted manual impact on the pathogenetic mechanisms of the disease.

A practical method to improve preoxygenation: Using the APL valve

Aim: After induction of anesthesia hypoxemia may rapidly develop due to hypoventilation, apnea and decrease in functional residual capacity. Thus, preoxygenation should be administered to every patient before anesthesia induction since airway management may unexpectedly be difficult. Applying positive airway pressure is reported to improve preoxygenation. In this study, we aimed to investigate the effect of applying positive pressure via the adjustable pressure limiting valve (APL) on preoxygenation. Material and Methods: 40 patients aged from 18 to 80 years to be operated under general anesthesia were included in this prospective randomized controlled study. The patients were randomly divided into two groups and preoxygenation was administered with anesthesia facemask in the supine position using two different techniques. In both techniques, the anesthesia circuit was flushed with O2 flush for 30 seconds and then preoxygenation was performed with 100% oxygen and 12 L/min of fresh gas flow for 3 min in spontaneous breathing. In Group APL the APL valve was set at 5 cmH2O pressure position. In Group SB, the APL valve was set at open (spontaneous) position. Results: The percentage of patients with an FeO2 of ≥ 90% at 3rd min was higher in Group APL than in Group SB (75% vs 40%, p=0.006). The mean FeO2 value at 3rd min was statistically significantly higher in Group APL (89.6 vs 88.2, p=0.001). The degree of the difficulty of the technique was reported to be higher in Group APL. Conclusion: In conclusion, we have shown that applying 5 cmH2O positive pressure by APL valve improved preoxygenation compared with spontaneous breathing.

Understanding the Adverse Hemodynamic Effects of Serious Thoracic Injuries During Cardiopulmonary Resuscitation: A Review and Approach Based on the Campbell Diagram.

Chest compressions during cardiopulmonary resuscitation (CPR) generate cardiac output during cardiac arrest. Their quality performance is key to achieving the return of spontaneous circulation. Serious thoracic injuries (STIs) are common during CPR, and they can change the shape and mechanics of the thorax. Little is known about their hemodynamic effects, so a review of this emerging concept is necessary. The Campbell diagram (CD) is a theoretical framework that integrates the lung and chest wall pressure-volume curves, allowing us to assess the consequences of STIs on respiratory mechanics and hemodynamics. STIs produce a decrease in the compliance of the chest wall and lung. The representation of STIs on the CD shows a decrease in the intrathoracic negative pressure and a functional residual capacity decrease during the thoracic decompression, leading to a venous return impairment. The thorax with STIs is more vulnerable to the adverse hemodynamic effects of leaning, hyperventilation, and left ventricular outflow tract obstruction during CPR. A better understanding of the effects of STIs during CPR, and the study of avoidable injuries, can help to improve the effectiveness of chest compressions and the survival in cardiac arrest.

EFFECT OF OBESITY ON OUTCOMES IN PATIENTS WITH COPD EXACERBATION REQUIRING BI-LEVEL NONINVASIVE VENTILATION

SESSION TITLE: Identifying Successes and Failures of NIV and Airway Clearance: From COPD to Neuromuscular Disease SESSION TYPE: Original Investigations PRESENTED ON: 10/21/2019 1:30 PM - 2:30 PM PURPOSE: Bi-level Non-Invasive Ventilation (NIV) is an important clinical tool used to improve acute hypercapnic respiratory acidosis, prevent endotracheal intubation, and decrease mortality in exacerbations of chronic obstructive pulmonary disease (COPD). However, studies show that one-third of patients who receive a trial of NIV fail, and the ability of physicians to determine success or failure rates is poor. Comorbid obesity and COPD is prevalent and associated with a higher risk of severe COPD exacerbation. In our study, we assessed the effect of body mass index (BMI) on the success of bi-level NIV in COPD exacerbation. METHODS: We performed a single-center, longitudinal retrospective cohort study of all patients admitted to a community hospital with the primary diagnosis of COPD exacerbation during a one-year period from June 2017 to June 2018. We excluded patients who did not require bi-level NIV during their stay or had a Do Not Resuscitate order at admission. 100 patients were included and divided into two groups; obese (BMI >/=30) and non-obese (BMI <30). Our primary outcome was bi-level NIV failure, defined as the need for intubation after bi-level NIV use. A Student t-test or Mann-Whitney U test was used for analysis of continuous variables. A χ² test or Fisher's exact test was used for analysis of categorical variables. RESULTS: Of 100 included admissions; we created an obese group (n=42, mean age 63.0 ± 8.8 years consisting of 29% males, 35.7% active smokers with average BMI 38.7); and a non-obese group (n=58, mean age 67.2 ± 11.4 years, consisting of 43% males, 58.6% active smokers with average BMI 22.3). Bi-level NIV failure was observed in 8 patients (19%) in the obese group and 1 (1.7%) in the non-obese group, a statistically significant difference (RR 2.37, 95% CI 1.67-3.38, p<0.01, Fisher’s exact test). When comparing obese vs non obese patients, Intensive Care Unit (ICU) admission was recorded in 28.6% vs 8.6% (p=0.014, Fisher’s exact test), with average ICU length of stay (LOS) 12.4 days vs 3.4 days and average hospital LOS 12.1 days vs 6.7 days (median 6.1 and 5.2, U=1047.5, p=0.235). Readmission rate at 30 days was 17.5% for obese patients vs 21.1% for non-obese patients, a difference that was not statistically significant. CONCLUSIONS: In patients with COPD exacerbation requiring bi-level NIV, obesity is associated with a higher risk of bi-level NIV failure and need for ICU admission. CLINICAL IMPLICATIONS: Identifying patients at higher risk of bi-level NIV failure will improve outcomes by enabling closer monitoring and early escalation of care. Mechanical effects of obesity on respiratory physiology such as decreased pulmonary compliance and a decrease in functional residual capacity below the closing capacity of small airways can result in atelectasis; a possible explanation for the high rates of bi-level NIV failure that we found in our study. DISCLOSURES: No relevant relationships by maen assali, source=Web Response no disclosure on file for David Benson; No relevant relationships by Ruth McGovern, source=Web Response No relevant relationships by Patricia Russo-Magno, source=Web Response No relevant relationships by Fatima Zeba, source=Web Response

Role of High-flow Nasal Oxygen Therapy in Cases with Pulmonary Hypertension in an Intensive Care Unit Setting.

High-flow nasal oxygen therapy warms and humidifies gases, allows better clearance of secretions, along with providing added benefits like preventing dehydration of airway surface, while decreasing atelectasis and thereby, offering comfort to the patient. While its effect on critically ill patients is still in its pioneering phase, there is lack of substantial evidence on the use of high-flow nasal cannula in cardiac patients with type I respiratory failure. We found it worthwhile to share our experience of its use in elderly and postpartum patients with moderate-to-severe pulmonary hypertension, with associated comorbidities and type I respiratory failure, with do-not-intubate or defer intubation status. In patients with pulmonary hypertension (PHT) and respiratory failure, endotracheal intubation followed by initiation of mechanical ventilation may have detrimental hemodynamic effects. Increase in lung volumes and decrease in functional residual capacity lead to increase in pulmonary hypertension and right ventricle afterload. If a patient has right heart failure, lung hyperinflation can fatally reduce cardiac output. High-flow nasal oxygen therapy may be of an advantage in these scenarios.How to cite this article: Gupta B, Kerai S, Kakkar K, Gupta L. Role of High-flow Nasal Oxygen Therapy in Cases with Pulmonary Hypertension in an Intensive Care Unit Setting. Indian J Crit Care Med 2019;23(10):458–461.

Laparoscopy and anesthesia: A clinical review

Laparoscopy has evolved since as early as 1950 to the present state of being the standard approach for most common surgical procedures. It has gained popularity in clinical practice in view of better cosmetics, lesser postoperative pain, shorter hospitalization, and faster recovery. However, the creation of pneumoperitoneum with laparoscopy is associated with various pathophysiological changes, especially involving the cardiovascular and respiratory systems. Electronic databases were searched to obtain the relevant literature with keywords related to laparoscopy from 1985 to 2016. Ninety-three papers were reviewed. Bibliographies were cross-checked and relevant literature was included. The pneumoperitoneum associated with laparoscopy is found to cause a decrease in cardiac output with an increase in pulmonary and systemic vascular resistance. These changes are mainly due to the increase in abdominal pressure which causes elevation of diaphragm with compression of small and big blood vessels. In the lungs, it causes a decrease in functional residual capacity with impaired pulmonary ventilation and perfusion. Increase in intra-abdominal pressure also perils the splanchnic circulation with a decrease in blood flow to the major abdominal organs. Preoperative assessment requires special attention, especially in high-risk patients. General anesthesia with controlled ventilation has proven to the ideal technique. Various pharmacological agents are used with varying success to attenuate the hemodynamic responses to laparoscopy. This article discusses the various consequences of laparoscopy as well as strategies to counteract them. It is essential for the anesthesiologists to have a good understanding of these changes and intervene at appropriate levels in terms of optimization in the preoperative period and management of hemodynamic changes in the perioperative period for a good surgical and patient outcome.

Evaluation of the role of lung volume and airway size and shape in supine-predominant obstructive sleep apnoea patients.

This study aimed to evaluate the involvement of airway cross-sectional area and shape, and functional residual capacity (FRC), in the genesis of obstructive sleep apnoea (OSA) in patients with supine-predominant OSA. Three groups were recruited: (i) supine OSA, defined as a supine apnoea-hyponoea index (AHI) at least twice that of the non-supine AHI; (ii) rapid eye movement (REM) OSA, defined as REM AHI at least twice the non-REM AHI and also selected to have supine AHI less than twice that of the non-supine AHI (i.e. to be non-positional); and (iii) no OSA, defined as an AHI less than five events per hour. The groups were matched for age, gender and body mass index. Patients underwent four-dimensional computed tomography scanning of the upper airway in the supine and lateral decubitus positions. FRC was measured in the seated, supine and lateral decubitus positions. Patients with supine OSA demonstrated a significant decrease in FRC of 340 mL (P = 0.026) when moving from the lateral to supine position compared to controls with no OSA, and REM OSA patients. We found no differences between groups in upper airway size and shape. However, all groups showed a significant change in airway shape with the velopharyngeal airway adopting a more elliptoid shape (with the long axis laterally oriented), with reduced anteroposterior diameter in the supine position. A fall in FRC when moving lateral to supine in supine OSA patients may be an important triggering factor in the generation of OSA in this patient group.

A rare case of postpoliomyelitis quadriparetic patient with severe kyphoscoliosis.

A rare case of postpoliomyelitis quadriparetic patient with severe kyphoscoliosis.

Recruitment of lung volume during surgery neither affects the postoperative spirometry nor the risk of hypoxaemia after laparoscopic gastric bypass in morbidly obese patients: a randomized controlled study

Intraoperative recruitment manoeuvres (RMs) combined with PEEP reverse the decrease in functional residual capacity (FRC) associated with anaesthesia and improve intraoperative oxygenation. Whether these benefits persist after operation remains unknown. We tested the hypothesis that intraoperative RMs associated with PEEP improve postoperative spirometry including FRC and reduce the incidence of postoperative hypoxaemia in morbidly obese (MO) patients undergoing laparoscopic gastric bypass. After IRB approval and informed consent, 50 MO patients undergoing laparoscopic gastric bypass under volume-controlled ventilation (tidal volume 6 ml kg(-1) of IBW) were randomly ventilated with either 10 cm H₂O PEEP or with 10 cm H₂O PEEP and one RM carried out after induction of pneumoperitoneum, and another after exsufflation. Anaesthesia and analgesia were standardized. Spirometry was assessed before operation and 24 h after surgery. Postoperative oxygenation and the apnoea-hypopnoea index (AHI) were recorded during the first postoperative night. Age, BMI, and STOP BANG score were similar in both groups. FRC decrease after surgery was minimal [0.15 (0.14) litre in control and 0.38 (0.19) litre in the RM group] and similar between the groups (P=0.35). FVC, FEV1, mean [Formula: see text], percentage of time spent with [Formula: see text] below 90%, and AHI did not differ significantly between the groups. This study demonstrates that when added to a protective mechanical ventilation combining low tidal volume and high PEEP, two RMs do not improve postoperative lung function including FRC, arterial oxygenation, and the incidence of obstructive apnoea in MO patients after laparoscopic upper abdominal surgery. EudraCT 2011-000999-33.

Impact of different breathing protocols on multiple-breath washout outcomes in children

To standardize multiple-breath washout (MBW) measurements, 1L tidal volume (VT) protocols were suggested. The effect on MBW derived ventilation inhomogeneity (VI) indices is unclear. We compared VI indices from free breathing MBW at baseline to 1L VT MBW performed in triplicates in 35 children (20 with CF). Mean (range) age was 12.8 (7.0-16.7) years, weight 42 (20-64) kg and height 151 (117-170) cm. Baseline lung clearance index (LCI) increased from mean (SD) 11.0 (2.2) to 13.0 (2.6), p = 0.011, in CF and from 6.8 (0.5) to 7.7 (1.4), p = 0.004, in controls. Moment ratio and Scond similarly increased. While change in VI indices was heterogeneous in individuals, decrease in functional residual capacity was most strongly associated with LCI increase. MBW protocols strongly influence measures of VI. The 1L VT MBW protocol leads to overestimation of VI and is not recommended in children.

Pulmonary function tests in obese people candidate to bariatric surgery

Obesity is considered one of the most serious public health problems of the modern world. Because it alters the relationship between the lungs, chest wall and diaphragm, it is to be expected that it impacts on the respiratory function. In Portugal, there is not much data about the relationship between obesity and pulmonary function.The aim of this study was to characterize respiratory function in morbidly obese patients and to evaluate whether weight loss in patients submitted to bariatric surgery affects pulmonary function tests (PFT).We conducted a retrospective study with 36 morbidly obese patients submitted to bariatric surgery, with a mean age of 40.6 years, 64% female and with a mean body mass index (BMI) of 49.7kg/m2. All patients were clinical and functionally evaluated before surgery and after their weight had stabilized following surgery. They underwent a complete pulmonary function testing with spirometry, lung volumes, carbon monoxide diffusing capacity (DLCO), maximum respiratory pressures and arterial blood gases analysis. Prior to surgery almost all the patients had functional respiratory changes, 34 had a decrease in functional residual capacity (FRC) 6 of whom a restrictive syndrome. Only 2 patients did not show any functional or arterial blood gas change. After bariatric surgery, BMI decreased to 34kg/m2 and there was a significant improvement in almost all functional parameters with resolution of restrictive disorders. Nevertheless, in 13 patients the FRC remained decreased.After weight loss, the only correlation found was between reduction of BMI and increased FRC (r=−0.371; p=0.028). This study suggests a relationship between obesity and pulmonary restriction and a positive impact of bariatric surgery in PFT.

Função pulmonar em doentes obesos submetidos a cirurgia bariátrica

Obesity is considered one of the most serious public health problems of the modern world. Because it alters the relationship between the lungs, chest wall and diaphragm, it is to be expected that it impacts on the respiratory function. In Portugal, there is not much data about the relationship between obesity and pulmonary function.The aim of this study was to characterize respiratory function in morbidly obese patients and to evaluate whether weight loss in patients submitted to bariatric surgery affects pulmonary function tests (PFT).We conducted a retrospective study with 36 morbidly obese patients submitted to bariatric surgery, with a mean age of 40.6 years, 64% female and with a mean body mass index (BMI) of 49.7 kg/m2. All patients were clinical and functionally evaluated before surgery and after their weight had stabilized following surgery. They underwent a complete pulmonary function testing with spirometry, lung volumes, carbon monoxide diffusing capacity (DLCO), maximum respiratory pressures and arterial blood gases analysis. Prior to surgery almost all the patients had functional respiratory changes, 34 had a decrease in functional residual capacity (FRC) 6 of whom a restrictive syndrome. Only 2 patients did not show any functional or arterial blood gas change. After bariatric surgery, BMI decreased to 34 kg/m2 and there was a significant improvement in almost all functional parameters with resolution of restrictive disorders. Nevertheless, in 13 patients the FRC remained decreased.After weight loss, the only correlation found was between reduction of BMI and increased FRC (r = −0.371; p = 0.028). This study suggests a relationship between obesity and pulmonary restriction and a positive impact of bariatric surgery in PFT.

Improving the survival and growth of African catfish (Clarias gariepinus) fingerlings by using Nile tilapi

General anaesthesia and many types of acute respiratory failure are accompanied by a decrease in functional residual capacity (FRC). This reduction promotes closure of dependent airways and alveolar collapse, thus impeding ventilation of these regions. Perfusion, on the other hand, is forced towards dependent regions by lowered pulmonary vascular pressure and increased alveolar pressure. Ventilation-perfusion (V/Q) inequality develops, impairing gas exchange and arterial oxygenation. Application of general positive end-expiratory pressure (PEEP) increases FRC and may improve gas exchange but cannot restore V/Q to normal. Differential ventilation, with equal distribution of ventilation between the lungs, and the application of PEEP solely to the dependent lung (selective PEEP) with the patient in the lateral position, improve V/Q matching and gas exchange with less impedance of cardiac output and less danger of barotrauma. This ventilation technique has proved successful in short-term experiments and in a small number of patients treated over several days.

POSITIVE END EXPIRATORY PRESSURE (PEEP);

Introduction: Thoracic surgeries and aesthesia for lung resection has presented anaesthesiologists with certain uniquephysiological problems. These include placing (lateral decubitus position) in order to obtain optimal access for most operations on lungs, pleura,esophagus, and great vessels, opening the chest wall (open pneumothorax) and one lung ventilation anaesthesia. One lung ventilationanaesthesia and lateral decubitus position produces decrease in functional residual capacity and an obligatory right to left shunt that rangesfrom 15% to 40% leading to increase in ventilation perfusion (V/Q) mismatch thus causing hypoxia and or hypoxemia. An optimal level ofpositive end expiratory pressure of 5cmH O when added to dependent lung is known to improve arterial oxygenation and improve ventilator 2efficiency. Objectives: To compare different values of positive end expiratory pressure (PEEP) during one lung ventilation, for its effects onblood arterial oxygenation and carbon dioxide levels. Study Design: Randomized controlled trial (RCT). Setting: Conducted in surgical Unit-IIIand Department of anaesthesia and Intensive Care, Combined Military Hospital, Rawalpindi. Duration of study with dates: Ten months from25-12-2008 to 01-10-2009, Additional quantum of Data was collected from 01-01-2011 to 25-01-2011. Subjects and methods: The patientswere divided into two equal groups of 100 patients each, by random allocation of patients to either in-group A (subjected to zero PEEP) or group-B (subjected to PEEP 5cm of water). Results: At induction and start of two lung ventilation 14 (14.0%) of the patients from group-A and 16(16.0%) from group-B had normal PaCO . At initiation of one lung ventilation 25 (25.0%) of the patients from group-A and 80 (80.0%) from group- 2B had normal PaO . At initiation of one lung ventilation 26 (26.0%) of the patients from group-A and 80 (80.0%) from group-B had normal PaCO 2 2with p &lt;0.001. At end of procedure one lung ventilation 30 (30.0%) of the patients from group-A and 90 (90.0%) from group-B had normal PaO . 2At end of procedure one lung ventilation 32 (32.0%) of the patients from group-A and 91 (91.0%) from group-B had normal PaCO . 2Conclusions: The execution of one-lung ventilation still constitutes a challenge in clinical and surgical practice.

Functional residual capacity-guided alveolar recruitment strategy after endotracheal suctioning in cardiac surgery patients

To determine whether the results of functional residual capacity measurements after endotracheal suctioning could guide the decision to perform an alveolar recruitment maneuver and thus improve lung function. Prospective, randomized, controlled interventional study. Intensive care unit of a university hospital. Fifty-nine mechanically ventilated patients within 2 hrs after elective cardiac surgery without preexisting lung diseases. Patients received a standard suctioning procedure with disconnection of the ventilator (20 secs, 14 F catheter, 200 cm H2O negative pressure). Prospectively, patients were stratified into two groups by the postsuctioning functional residual capacity value (group A: functional residual capacity >94% of baseline; group B: functional residual capacity <94% of baseline). Both groups were randomized into either a recruitment maneuver (RM) group (positive end-expiratory pressure 15 cm H2O, peak inspiratory pressure 35-40 cm H2O for 30 secs, group RM) or a non-RM group, in which ventilation was resumed without an RM (group NRM), resulting in four groups. Functional residual capacity and arterial blood gases were recorded for up to 1 hr. In addition, distribution of ventilation was measured by means of electrical impedance tomography. The RM had an impact on distribution of ventilation, functional residual capacity, and oxygenation in patients with a decrease of functional residual capacity after suctioning. In contrast, the RM showed no impact on these parameters in patients with no decrease of functional residual capacity after suctioning. By measurements of functional residual capacity after endotracheal suctioning, patients profiting from a consecutive recruitment maneuver could be identified. Guiding the recruitment strategy on changes of functional residual capacity may improve patient care.

Acute Bronchodilator Responsiveness in Bronchiolitis Obliterans Syndrome Following Hematopoietic Stem Cell Transplantation

The obstructive abnormality of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic stem cell transplantation (HSCT) is deemed to be virtually insensitive to treatment with inhaled bronchodilators. We studied whether nonconventional assessment of bronchodilation may help to detect physiologically meaningful airway responses missed by traditional criteria. Standard spirometry, partial and maximal expiratory flow-volume curves, and lung volumes were measured before and 90 min after inhalation of albuterol plus tiotropium in 17 patients who developed mild to very severe BOS following HSCT. After treatment with bronchodilators, the standard criteria of reversibility based on FEV1 and FVC were met in seven out of 17 patients. In eight patients, residual volume (RV) decreased beyond its within-session spontaneous variability, and functional residual capacity (FRC) was reduced in four of them. Partial forced expiratory flow (Vpart) increased beyond its within-session spontaneous variability in nine patients. Out of 10 patients in whom neither FEV1 nor FVC met the standard criteria of reversibility, six had a positive increase in Vpart or a decrease of lung hyperinflation (ie, FRC) or RV. In six patients with limited expiratory flow during tidal breathing, the postbronchodilator increase in Vpart was correlated with a decrease in FRC (R2=0.83; P=.011). This study suggests that airway smooth muscle tone plays a significant role in BOS after HSCT and that the common knowledge of BOS as an irreversible obstructive disease may stem from the limitation of simple spirometry to detect changes in small airways. ClinicalTrials.gov; No.: NCT01112241 (BOS-01); URL: www.clinicaltrials.gov.

Manual hyperinflation partly prevents reductions of functional residual capacity in cardiac surgical patients - a randomized controlled trial

IntroductionCardiac surgery is associated with post-operative reductions of functional residual capacity (FRC). Manual hyperinflation (MH) aims to prevent airway plugging, and as such could prevent the reduction of FRC after surgery. The main purpose of this study was to determine the effect of MH on post-operative FRC of cardiac surgical patients.MethodsThis was a randomized controlled trial of patients after elective coronary artery bypass graft and/or valve surgery admitted to the intensive care unit (ICU) of a university hospital. Patients were randomly assigned to a "routine MH group" (MH was performed within 30 minutes after admission to the ICU and every 6 hours thereafter, and before tracheal extubation), or a "control group" (MH was performed only if perceptible (audible) sputum was present in the larger airways causing problems with mechanical ventilation, or if oxygen saturation (SpO2) dropped below 92%). The primary endpoint was the reduction of FRC from the day before cardiac surgery to one, three, and five days after tracheal extubation. Secondary endpoints were SpO2 (at similar time points) and chest radiograph abnormalities, including atelectasis (at three days after tracheal extubation).ResultsA total of 100 patients were enrolled. Patients in the routine MH group showed a decrease of FRC on the first post-operative day to 71% of the pre-operative value, versus 57% in the control group (P = 0.002). Differences in FRC became less prominent over time; differences between the two study groups were no longer statistically significant at Day 5. There were no differences in SpO2 between the study groups. Chest radiographs showed more abnormalities (merely atelectasis) in the control group compared to patients in the routine MH group (P = 0.002).ConclusionsMH partly prevents the reduction of FRC in the first post-operative days after cardiac surgery.Trial registrationNetherlands Trial Register (NTR): NTR1384. http://www.trialregister.nl

Changes in Functional Residual Capacity and Lung Mechanics during Surgical Repair of Congenital Heart Diseases

To characterize the impact of lung volume changes in the lung function impairment after the surgical repair of congenital heart diseases, combined measurements of functional residual capacity, lung clearance index, and respiratory mechanics were performed in children with hypoperfused lungs (tetralogy of Fallot [TOF]) or with pulmonary hyperperfusion (ventricular septal defect [VSD]). Lung volume and clearance were assessed by using a sulfur hexafluoride washout technique, and the mechanical properties of the respiratory system were assessed using a low-frequency oscillation technique. Lung volume and oscillatory measurements were made preoperatively, before and after cardiopulmonary bypass and aortic clamping (AC), and after chest closure. Impairments in airway (36 +/- 2%) and tissue mechanics (22 +/- 3%) were observed in the children with TOF after bypass; AC and chest closure were associated with marked decreases in functional residual capacity (-24 +/- 3% and -13 +/- 2% for TOF and VSD after AC, respectively) and increases in lung clearance index (-60 +/- 6% and -24 +/- 3% for TOF and VSD after AC, respectively). Smaller impairments in lung mechanics were observed after bypass and AC in children with VSD. These findings suggest that the lung volume loss and lung mechanical deteriorations are probably caused by a diminished tethering effect of the lung periphery through a reduced filling of the pulmonary capillaries. This effect seems to be more pronounced in children with hypoperfused lungs (TOF) than in those with pulmonary hyperperfusion (VSD). The beneficial postoperative changes in children with VSD are consequences of the reversal of the pulmonary vascular engorgement after surgical repair.