scholarly journals Goal-Directed Mechanical Ventilation: Are We Aiming at the Right Goals? A Proposal for an Alternative Approach Aiming at Optimal Lung Compliance, Guided by Esophageal Pressure in Acute Respiratory Failure

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Arie Soroksky ◽  
Antonio Esquinas
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Acute Respiratory Failure ◽  
Chest Wall ◽  
Respiratory System ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Plateau Pressure ◽  
Lung Compliance ◽  
Inspiratory Pressure

Patients with acute respiratory failure and decreased respiratory system compliance due to ARDS frequently present a formidable challenge. These patients are often subjected to high inspiratory pressure, and in severe cases in order to improve oxygenation and preserve life, we may need to resort to unconventional measures. The currently accepted ARDSNet guidelines are characterized by a generalized approach in which an algorithm for PEEP application and limited plateau pressure are applied to all mechanically ventilated patients. These guidelines do not make any distinction between patients, who may have different chest wall mechanics with diverse pathologies and different mechanical properties of their respiratory system. The ability of assessing pleural pressure by measuring esophageal pressure allows us to partition the respiratory system into its main components of lungs and chest wall. Thus, identifying the dominant factor affecting respiratory system may better direct and optimize mechanical ventilation. Instead of limiting inspiratory pressure by plateau pressure, PEEP and inspiratory pressure adjustment would be individualized specifically for each patient's lung compliance as indicated by transpulmonary pressure. The main goal of this approach is to specifically target transpulmonary pressure instead of plateau pressure, and therefore achieve the best lung compliance with the least transpulmonary pressure possible.

scholarly journals Protective PEEP and Lung Capacity May Be Determined by a Rapid PEEP-step Procedure

2021 ◽  
Author(s):  
Christina Grivans ◽  
Ola Stenqvist
Keyword(s):  
Tidal Volume ◽  
Peep Level ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Plateau Pressure ◽  
Lung Compliance ◽  
Driving Pressure ◽  
High Peep ◽  
Step Procedure ◽  
Protective Ventilation Strategy

Abstract Background: A protective ventilation strategy should be based on assessment of lung mechanics and transpulmonary pressure, as this is the pressure that directly “hits” the lung. Esophageal pressure has been used for this purpose but has not gained widespread clinical acceptance. Instead, respiratory system mechanics and airway driving pressure have been used as surrogate measures. We have shown that the lung P/V curve coincides with the line connecting the end-expiratory airway P/V points of a PEEP trial. Consequently, transpulmonary pressure increases as much as PEEP is increased. If the change in end-expiratory lung volume (ΔEELV) is determined, lung compliance (CL) can be determined as ΔEELV/ΔPEEP and ΔPTP as tidal volume times ΔPEEP/ΔEELV. Methods: In ten patients with acute respiratory failure, ΔEELV was measured during each 4 cmH2O PEEP-step from 0 to 16 cmH2O and CL for each PEEP interval calculated as ΔEELV/ΔPEEP giving a lung P/V curve for the whole PEEP trial. Results: Lung P/V curves showed a marked individual variation with an overall lung compliance of 43–143 ml/cmH2O (total inspiratory volume divided by end-inspiratory transpulmonary plateau pressure at PEEP 16 cmH2O). The two patients with lowest lung compliance were non-responders to PEEP with decreasing lung compliance at high PEEP levels, indicating over-distension. Patients with higher lung compliance had a positive response to PEEP with successively higher lung compliance when increasing PEEP. A two-step PEEP procedure starting from a clinical PEEP level of 8 cmH2O gave almost identical lung P/V curves as the four PEEP-step procedure. The ratio of airway driving pressure (ΔPAW) to transpulmonary driving pressure (ΔPTP/ΔPAW) varied between patients and changed with PEEP, reducing the value of ΔPAW as surrogate for ΔPTP in individual patients. Conclusion: Separation of lung and chest wall mechanics can be achieved without esophageal pressure measurements if ΔEELV is determined when PEEP is changed . Only a two-step PEEP procedure is required for obtaining a lung P/V curve from baseline clinical PEEP to end-inspiration at the highest PEEP level, which can be used to determine the PEEP level where transpulmonary driving pressure is lowest and possibly least injurious for any given tidal volume.Trial registration: ClinicalTrials.gov, NCT04484727. Registered 24 July 2020 – Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04484727?term=Lindgren%2C+Sophie&cntry=SE&draw=2&rank=1

scholarly journals Respiratory mechanical effects of surgical pneumoperitoneum in humans

2014 ◽  
Vol 117 (9) ◽  
pp. 1074-1079 ◽  
Author(s):  
Stephen H. Loring ◽  
Negin Behazin ◽  
Aileen Novero ◽  
Victor Novack ◽  
Stephanie B. Jones ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Positive End Expiratory Pressure ◽  
Before And After ◽  
Show Evidence ◽  
Obese Subjects

Pneumoperitoneum for laparoscopic surgery is known to stiffen the chest wall and respiratory system, but its effects on resting pleural pressure in humans are unknown. We hypothesized that pneumoperitoneum would raise abdominal pressure, push the diaphragm into the thorax, raise pleural pressure, and squeeze the lung, which would become stiffer at low volumes as in severe obesity. Nineteen predominantly obese laparoscopic patients without pulmonary disease were studied supine (level), under neuromuscular blockade, before and after insufflation of CO2 to a gas pressure of 20 cmH2O. Esophageal pressure (Pes) and airway pressure (Pao) were measured to estimate pleural pressure and transpulmonary pressure (Pl = Pao − Pes). Changes in relaxation volume (Vrel, at Pao = 0) were estimated from changes in expiratory reserve volume, the volume extracted between Vrel, and the volume at Pao = −25 cmH2O. Inflation pressure-volume (Pao-Vl) curves from Vrel were assessed for evidence of lung compression due to high Pl. Respiratory mechanics were measured during ventilation with a positive end-expiratory pressure of 0 and 7 cmH2O. Pneumoperitoneum stiffened the chest wall and the respiratory system (increased elastance), but did not stiffen the lung, and positive end-expiratory pressure reduced Ecw during pneumoperitoneum. Contrary to our expectations, pneumoperitoneum at Vrel did not significantly change Pes [8.7 (3.4) to 7.6 (3.2) cmH2O; means (SD)] or expiratory reserve volume [183 (142) to 155 (114) ml]. The inflation Pao-Vl curve above Vrel did not show evidence of increased lung compression with pneumoperitoneum. These results in predominantly obese subjects can be explained by the inspiratory effects of abdominal pressure on the rib cage.

scholarly journals Investigating the Effect of Expiratory Time Constant on Outcome in Intubated Patients with Acute Respiratory Failure Caused by COVID-19 in Critical Care Unit: A Research Study

2021 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Fatemeh Eghtedari ◽  
Shahnaz Fooladi ◽  
Ali Mohammadian Erdi ◽  
Atefeh Shadman ◽  
Mahzad Yousefian
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Acute Respiratory Failure ◽  
Time Constant ◽  
Lung Compliance ◽  
Cross Sectional ◽  
Expiratory Time ◽  
Significant Difference ◽  
Lung Resistance ◽  
The Mean

Background: The coronavirus disease 2019 (COVID-19) has a high prevalence and mortality worldwide. Thousands of patients with acute respiratory failure caused by COVID-19 are daily hospitalized in intensive care units (ICUs) around the world. Many of these patients require full mechanical respiratory support and long-term ventilator use. Using different ventilators and calculating important variables can be helpful in meeting therapeutic needs of patients. Objectives: The aim of present study was to investigate the effect of expiratory time constant (RCEXP) on the course of treatment and duration of mechanical ventilation in patients with acute respiratory failure hospitalized in ICU. Methods: The present cross-sectional study was conducted on 60 patients with acute respiratory failure who were hospitalized in the ICU and underwent mechanical ventilation due to COVID-19 in the first six months of 2020. The variables of RCEXP, lung compliance and lung resistance in all patients were recorded daily and analyzed. Then, based on clinical outcome, the patients were divided into two groups: the patients with wean outcome (N = 40) and those with death outcome (N = 20). Results: The mean ± SD of lung compliance in patients who were separated from ventilator and patients with death outcome were 74.73 (18.58) mL/cm H2O and 36.92 (10.56) mL/cm H2O, respectively, which was statistically significant (P = 0.001). The mean ± SD of lung resistance in patients who were separated from ventilator and patients with death outcome were calculated at 9.25 (4.62) and 14 (6.5), respectively, which was statistically significant (P = 0.015). Also, there was a statistically significant difference between the two groups in terms of mean ± SD of RCEXP (0.67 (0.23) vs. 0.49 (0.19), P = 0.010). Conclusions: According to the results of this study, there was a significant difference between high resistance, low compliance, RCEXP, and weaning success of intubation in patients hospitalized in the ICU.

scholarly journals The Association Between the Mechanical Ventilator Pressures and Outcomes in a Cohort of Patients with Acute Respiratory Failure

2020 ◽  
Vol 14 ◽  
pp. 117954842096624
Author(s):  
Hawa Edriss ◽  
Shengping Yang ◽  
Edna Juarez ◽  
Joshua Crane ◽  
Michelle Lear ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Length Of Stay ◽  
Acute Respiratory Failure ◽  
Peak Pressure ◽  
Plateau Pressure ◽  
Driving Pressure ◽  
Mechanical Ventilator ◽  
The Mean ◽  
Pressure Plateau

Background: Pressures measured during mechanical ventilation provide important information about the respiratory system mechanics and can help predict outcomes. Methods: The electronic medical records of patients hospitalized between 2010 and 2016 with sepsis who required mechanical ventilation were reviewed to collect demographic information, clinical information, management requirements, and outcomes, such as mortality, ICU length of stay, and hospital length of stay. Mechanical ventilation pressures were recorded on the second full day of hospitalization. Results: This study included 312 adult patients. The mean age is 59.1 ± 16.3 years; 57.4% were men. The mean BMI was 29.3 ± 10.7. Some patients had pulmonary infections (46.2%), and some patients had extrapulmonary infections (34.9%). The overall mortality was 42.6%. In a multi-variable model that included age, gender, number of comorbidities, APACHE 2 score, and PaO2/FiO2 ratio, peak pressure, plateau pressure, driving pressure, and PEEP all predicted mortality when entered into the model separately. There was an increase in peak pressure, plateau pressure, and driving pressure across BMI categories ranging from underweight to obese. Conclusions: This study demonstrates that ventilator pressure measurements made early during the management of patients with acute respiratory failure requiring mechanical ventilation provide prognostic information regarding outcomes, including mortality. Patients with high mechanical ventilator pressures during the early course of their acute respiratory failure require more attention to identify reversible disease processes when possible. In addition, increased BMIs are associated with increased ventilator pressures, and this increases the complexity of the clinical evaluation in the management of obese patients.

scholarly journals Surgical tracheostomy in a cohort of COVID-19 patients

HNO ◽  
2021 ◽  
Author(s):  
Patrick J. Schuler ◽  
Jens Greve ◽  
Thomas K. Hoffmann ◽  
Janina Hahn ◽  
Felix Boehm ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Prolonged Mechanical Ventilation ◽  
Tertiary Care ◽  
Lung Compliance ◽  
Hypoxemic Respiratory Failure ◽  
Surgical Tracheostomy ◽  
Increased Risk ◽  
Open Surgical Tracheostomy ◽  
Sedative Drugs

Abstract Background One of the main symptoms of severe infection with the new coronavirus‑2 (SARS-CoV-2) is hypoxemic respiratory failure because of viral pneumonia with the need for mechanical ventilation. Prolonged mechanical ventilation may require a tracheostomy, but the increased risk for contamination is a matter of considerable debate. Objective Evaluation of safety and effects of surgical tracheostomy on ventilation parameters and outcome in patients with COVID-19. Study design Retrospective observational study between March 27 and May 18, 2020, in a single-center coronavirus disease-designated ICU at a tertiary care German hospital. Patients Patients with COVID-19 were treated with open surgical tracheostomy due to severe hypoxemic respiratory failure requiring mechanical ventilation. Measurements Clinical and ventilation data were obtained from medical records in a retrospective manner. Results A total of 18 patients with confirmed SARS-CoV‑2 infection and surgical tracheostomy were analyzed. The age range was 42–87 years. All patients received open tracheostomy between 2–16 days after admission. Ventilation after tracheostomy was less invasive (reduction in PEAK and positive end-expiratory pressure [PEEP]) and lung compliance increased over time after tracheostomy. Also, sedative drugs could be reduced, and patients had a reduced need of norepinephrine to maintain hemodynamic stability. Six of 18 patients died. All surgical staff were equipped with N99-masks and facial shields or with powered air-purifying respirators (PAPR). Conclusion Our data suggest that open surgical tracheostomy can be performed without severe complications in patients with COVID-19. Tracheostomy may reduce invasiveness of mechanical ventilation and the need for sedative drugs and norepinehprine. Recommendations for personal protective equipment (PPE) for surgical staff should be followed when PPE is available to avoid contamination of the personnel.

Comparative study between noninvasive positive pressure ventilation and invasive mechanical ventilation in patients with respiratory failure

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Mohammed N Al Shafi'i ◽  
Doaa M. Kamal El-din ◽  
Mohammed A. Abdulnaiem Ismaiel ◽  
Hesham M Abotiba
Keyword(s):  
Intensive Care Unit ◽  
Mechanical Ventilation ◽  
Intensive Care ◽  
Respiratory Failure ◽  
Acute Respiratory Failure ◽  
Positive Pressure Ventilation ◽  
Invasive Mechanical Ventilation ◽  
Noninvasive Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Significant Difference

Abstract Background Noninvasive positive pressure ventilation (NIPPV) has been increasingly used in the management of respiratory failure in intensive care unit (ICU). Aim of the Work is to compare the efficacy and resource consumption of NIPPMV delivered through face mask against invasive mechanical ventilation (IMV) delivered by endotracheal tube in the management of patients with acute respiratory failure (ARF). Patients and Methods This prospective randomized controlled study included 78 adults with acute respiratory failure who were admitted to the intensive care unit. The enrolled patients were randomly allocated to receive either noninvasive ventilation or conventional mechanical ventilation (CMV). Results Severity of illness, measured by the simplified acute physiologic score 3 (SAPS 3), were comparable between the two patient groups with no significant difference between them. Both study groups showed a comparable steady improvement in PaO2:FiO2 values, indicating that NIPPV is as effective as CMV in improving the oxygenation of patients with ARF. The PaCO2 and pH values gradually improved in both groups during the 48 hours of ventilation. 12 hours after ventilation, NIPPMV group showed significantly more improvement in PaCO2 and pH than the CMV group. The respiratory acidosis was corrected in the NIPPV group after 24 hours of ventilation compared with 36 hours in the CMV group. NIPPV in this study was associated with a lower frequency of complications than CMV, including ventilator acquired pneumonia (VAP), sepsis, renal failure, pulmonary embolism, and pancreatitis. However, only VAP showed a statistically significant difference. Patients who underwent NIPPV in this study had lower mortality, and lower ventilation time and length of ICU stay, compared with patients on CMV. Intubation was required for less than a third of patients who initially underwent NIV. Conclusion Based on our study findings, NIPPV appears to be a potentially effective and safe therapeutic modality for managing patients with ARF.

scholarly journals Thoracic sympathetic block reduces respiratory system compliance

2007 ◽  
Vol 125 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Fábio Ely Martins Benseñor ◽  
Joaquim Edson Vieira ◽  
José Otávio Costa Auler Júnior
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Resection ◽  
Lung Compliance ◽  
Airway Hyperreactivity ◽  
Sympathetic Block ◽  
Respiratory System Compliance ◽  
Double Blind ◽  
Thoracic Epidural ◽  
Student’S T

CONTEXT AND OBJECTIVE: Thoracic epidural anesthesia (TEA) following thoracic surgery presents known analgesic and respiratory benefits. However, intraoperative thoracic sympathetic block may trigger airway hyperreactivity. This study weighed up these beneficial and undesirable effects on intraoperative respiratory mechanics. DESIGN AND SETTING: Randomized, double-blind clinical study at a tertiary public hospital. METHODS: Nineteen patients scheduled for partial lung resection were distributed using a random number table into groups receiving active TEA (15 ml 0.5% bupivacaine, n = 9) or placebo (15 ml 0.9% saline, n = 10) solutions that also contained 1:200,000 epinephrine and 2 mg morphine. Under general anesthesia, flows and airway and esophageal pressures were recorded. Pressure-volume curves, lower inflection points (LIP), resistance and compliance at 10 ml/kg tidal volume were established for respiratory system, chest wall and lungs. Student’s t test was performed, including confidence intervals (CI). RESULTS: Bupivacaine rose 5 ± 1 dermatomes upwards and 6 ± 1 downwards. LIP was higher in the bupivacaine group (6.2 ± 2.3 versus 3.6 ± 0.6 cmH2O, p = 0.016, CI = -3.4 to -1.8). Respiratory system and lung compliance were higher in the placebo group (respectively 73.3 ± 10.6 versus 51.9 ± 15.5, p = 0.003, CI = 19.1 to 23.7; 127.2 ± 31.7 versus 70.2 ± 23.1 ml/cmH2O, p < 0.001, CI = 61 to 53). Resistance and chest wall compliance showed no difference. CONCLUSION: TEA decreased respiratory system compliance by reducing its lung component. Resistance was unaffected. Under TEA, positive end-expiratory pressure and recruitment maneuvers are advisable.

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