Spontaneous Ventilation Mode Research Articles

Effects of three spontaneous ventilation modes on respiratory drive and muscle effort in COVID-19 pneumonia patients

BackgroundHigh drive and high effort during spontaneous breathing can generate patient self-inflicted lung injury (P-SILI) due to uncontrolled high transpulmonary and transvascular pressures, with deterioration of respiratory failure. P-SILI has been demonstrated in experimental studies and supported in recent computational models. Different treatment strategies have been proposed according to the phenotype of elastance of the respiratory system (Ers) for patients with COVID-19. This study aimed to investigate the effect of three spontaneous ventilation modes on respiratory drive and muscle effort in clinical practice and their relationship with different phenotypes. This was achieved by obtaining the following respiratory signals: airway pressure (Paw), flow (V´) and volume (V) and calculating muscle pressure (Pmus).MethodsA physiologic observational study of a series of cases in a university medical-surgical ICU involving 11 mechanically ventilated patients with COVID-19 pneumonia at the initiation of spontaneous breathing was conducted. Three spontaneous ventilation modes were evaluated in each of the patients: pressure support ventilation (PSV), airway pressure release ventilation (APRV), and BiLevel positive airway pressure ventilation (BIPAP). Pmus was calculated through the equation of motion. For this purpose, we acquired the signals of Paw, V´ and V directly from the data transmission protocol of the ventilator (Dräger). The main physiological measurements were calculation of the respiratory drive (P0.1), muscle effort through the ΔPmus, pressure‒time product (PTP/min) and work of breathing of the patient in joules multiplied by respiratory frequency (WOBp, J/min).ResultsTen mechanically ventilated patients with COVID-19 pneumonia at the initiation of spontaneous breathing were evaluated. Our results showed similar high drive and muscle effort in each of the spontaneous ventilatory modes tested, without significant differences between them: median (IQR): P0.1 6.28 (4.92–7.44) cm H2O, ∆Pmus 13.48 (11.09–17.81) cm H2O, PTP 166.29 (124.02–253.33) cm H2O*sec/min, and WOBp 12.76 (7.46–18.04) J/min. High drive and effort were found in patients even with low Ers. There was a significant relationship between respiratory drive and WOBp and Ers, though the coefficient of variation widely varied.ConclusionsIn our study, none of the spontaneous ventilatory methods tested succeeded in reducing high respiratory drive or muscle effort, regardless of the Ers, with subsequent risk of P-SILI.

Utilizing Spontaneous Ventilation Modes in Patients Underwent Corrective Surgery for Right Ventricular Outflow Tract Obstructive Congenital Heart Disease: A Crossover Study.

This study aimed to determine whether the hemodynamics of patients with right ventricle outflow tract obstructive congenital heart disease (RVOTO-CHD) improve after corrective surgery by changing the ventilation mode. Patients with RVOTO-CHD who underwent corrective surgery were enrolled in this study. Echocardiography and advanced hemodynamic monitoring were performed using the pulse indicator continuous cardiac output (PiCCO) technology in the pressure-regulated volume control (PRVC) mode, followed with switching to the pressure support ventilation (PSV) mode and neurally adjusted ventilatory assist (NAVA) mode in random order. Overall, 31 patients were enrolled in this study from April 2021 to October 2021. Notably, changing the ventilation mode from PRVC to a spontaneous mode (PSV or NAVA) led to better cardiac function outcomes, including right ventricular cardiac index (PRVC: 3.19 1.07 L/min/ vs. PSV: 3.45 1.32 L/min/ vs. NAVA: 3.82 1.03 L/min/ , p 0.05) and right ventricle contractility (tricuspid annular peak systolic velocity) (PRVC: 6.58 1.40 cm/s vs. PSV: 7.03 1.33 cm/s vs. NAVA: 7.94 1.50 cm/s, p 0.05), as detected via echocardiography. Moreover, in the NAVA mode, PiCCO-derived cardiac index (PRVC: 2.92 0.54 L/min/ vs. PSV: 3.04 0.56 L/min/ vs. NAVA: 3.20 0.62 L/min/ , p 0.05), stroke volume index (PRVC: 20.38 3.97 mL/ vs. PSV: 21.23 4.33 mL/ vs. NAVA: 22.00 4.33 mL/ , p 0.05), and global end diastolic index (PRVC: 295.74 78.39 mL/ vs. PSV: 307.26 91.18 mL/ vs. NAVA: 323.74 102.87 mL/ , p 0.05) improved, whereas extravascular lung water index significantly reduced (PRVC: 16.42 7.90 mL/kg vs. PSV: 15.42 5.50 mL/kg vs. NAVA: 14.4 4.19 mL/kg, p 0.05). Furthermore, peak inspiratory pressure, mean airway pressure, driving pressure, and compliance of the respiratory system improved in the NAVA mode. No deaths were reported in this study. We found that utilizing spontaneous ventilator modes, especially the NAVA mode, after corrective surgery in patients with RVOTO-CHD may improve their right heart hemodynamics and respiratory mechanics. However, further randomized controlled trials are required to verify the advantages of spontaneous ventilation modes in such patients. NCT04825054.

Effect of pressure support ventilation vs. spontaneous ventilation on lung atelectasis during recovery from anesthesia for laparoscopic gastric sleeve surgery

Background & Objective: Pressure support ventilation (PSV) is a target pressure mode that offers breath by breath mode of ventilation support, started by patients, and timed to respiratory effort. The fundamental idea behind PSV is to assist spontaneous breathing in response to the patient-initiated breaths. We evaluated the effects of PSV and spontaneous ventilation during awakening from anesthesia on lung atelectasis in the patients following laparoscopic gastric sleeve surgery. Methodology: Following clearance from the institutional ethical council, we enrolled 64 patients and divided them into two groups at random; pressure support group (Group PS) to receive PSV, and control group or spontaneous group (Group S) to continue with spontaneous ventilation mode during awakening from anesthesia in the patients following laparoscopic gastric sleeve surgery. Results: In the pressure support group, atelectasis was less common than in the control group at PACU (P = 0.042). Over the first 48 h following surgery, there were substantial differences between the groups in the level of oxygen saturation as determined by pulse oximetry ≤ 92%. The incidence of SpO2 ≤ 92% during 48 h postoperatively in the Group S and Group PS was 34% vs 12% respectively. No patient needed mechanical ventilatory support during the 48 h postoperatively. Conclusions: Pressure support ventilation during the recovery from general anesthesia to patients after laparoscopic gastric sleeve surgery resulted in reduced incidence of postoperative atelectasis than those who were allowed spontaneous ventilation with occasional manual support. Abbreviations: PACU: Post-Anesthesia Care Unit; PEEP: Positive End Expiratory Pressure; PSV: Pressure support ventilation; VT: Tidal Volume. Key words: Gastric sleeve surgery; Laparoscopy; Lung atelectasis; Pressure support ventilation; Spontaneous ventilation. Citation: Aboelsuod MAA, Farhat AEA, Abdalla AM, Hassnin FSB. The effect of pressure support ventilation vs. spontaneous ventilation on lung atelectasis during recovery from anesthesia for laparoscopic gastric sleeve surgery. Anaesth. pain intensive care. 2023;27(3):301−307.DOI: 10.35975/apic.v27i3.2166 Received: March 09, 2023; Reviewed: March 20, 2023; Accepted: April 16, 2023.

Pneumomediastinum: An Aspect of Pulmonary Barotrauma during Noninvasive Ventilation in a COVID-19 Patient

Introduction: The new coronavirus, SARS-Cov-2, responsible for COVID-19, was identified at the end of 2019 as the agent responsible for many cases of severe respiratory failure. the treatment of patients suffering from respiratory failure due to SARS-Cov-2 pneumonia is essentially based on protective ventilatory management, which usually constitutes an essential therapeutic component in the treatment of acute respiratory distress syndrome (ARDS). However, it can be responsible for serious side effects, including pulmonary barotrauma. This observation reports an unusual appearance of barotrauma. Observation: A 65-year-old man, with a history of diabetes on oral anti-diabetics, was admitted to intensive care for treatment of severe pneumonitis due to COVID-19. The onset of the symptoms was marked by a fever of 39°C, an influenza-like illness and progressive dyspnea at rest. Biologically, the patient had lymphopenia at 640 uL, CRP at 206.74 mg/l, with a D-Dimer at 2.67 ug/l. a PCR for Covid-19 was requested, was positive. The thoracic scanner shows bilateral diffuse ground glass hyper density in the central and subpleural territories, the damage of which is estimated at 60% in favor of severe Covid-19. In arterial blood gas, chronic respiratory alkalosis with hypoxemia was observed. In view of the hypoxemic state of the patient, it was decided to put the patient on non-invasive mechanical ventilation (NIV), in spontaneous ventilation mode with inspiratory support. The patient showed clinical improvement with a respiratory rate of 18 Cyc/min and a saturation of 94% with an FiO2 of 100%. In order to limit the risk of barotrauma, protective ventilation was performed. The positive expiratory pressure (PEEP) was at 8 cmH2O with the objective of a plateau pressure <30 cmH2O with a pressure support level at 8 cmH2O to obtain a respiratory rate between 15 and 25 Cyc/min. On the fourth day of NIV, appearance of bilateral thoracic subcutaneous emphysema extending .............

Global and Regional Tidal Volume Distribution in Spontaneously Breathing Mechanically Ventilated Children.

Allowing the ventilated adult patient to breathe spontaneously may improve tidal volume (VT) distribution toward the dependent lung regions, reduce shunt fraction, and decrease dead space. It has not been studied if these effects under various levels of ventilatory support also occur in children. We sought to explore the effect of level of ventilatory support on VT distribution and end-expiratory lung volume (EELV) in spontaneously breathing ventilated children in the recovery phase of their acute respiratory failure. This is a secondary analysis of data from a prospective clinical trial comparing 2 different ventilator modes during weaning in mechanically ventilated children < 5 y: CPAP + pressure support ventilation (PSV) and pressure control (PC)/intermittent mandatory ventilation (IMV) + PSV with the mandatory breath rate set at 25% of baseline. Using electrical impedance tomography (EIT), we assessed VT distribution by calculating the center of ventilation. Polynomial functions of the second degree were plotted to evaluate regional lung filling characteristics. Changes in end-expiratory impedance were calculated to assess changes in EELV. Baseline measurements were compared with measurements during CPAP/PSV, PC/IMV + PSV, and during a downward titration of the level of pressure support. Thirty-five subjects with a median age 4.5 (2.1-12.9) months and a median ventilation time of 4.9 (3.3-6.9) d were studied. The overall median coefficient of variation was 50.1% and not different between CPAP/PSV or PC/synchronized IMV + PSV. Regional filling characteristics of the lung identified a homogeneous VT distribution under all study conditions. Downtapering of the level of PSV resulted in a significant shift of the coefficient of variation toward the dependent lung regions. Our data showed that allowing ventilated children in the recovery phase of respiratory failure to breathe spontaneously in a continuous spontaneous ventilation mode did not negatively affect VT distribution or EELV.

Ventilator induced Diaphragmatic Dysfunction assessed by Ultrasonography and its impact on Weaning outcome

Abstract Background Ventilator induced diaphragmatic dysfunction (VIDD), as a loss of diaphragmatic force generating capacity due to the use of mechanical ventilation. Difficulties in discontinuing ventilatory support are encountered in 20–25% of mechanically ventilated patients, with a staggering 40% of time spent in the intensive care unit being devoted to weaning. M-mode ultrasonography is now an accepted qualitative method of assessing diaphragmatic motion in normal and pathological conditions. In this study, we evaluated whether diaphragmatic excursion (DE) as measured by M-mode sonography can be a predictor of weaning and diagnosis of VIDD. Aim The aim of this study is to determine the presence of ventilator induced diaphragmatic dysfunction (VIDD) diagnosed by M-mode ultrasonography and its impact on weaning outcome. Methodology This study was conducted prospectively in critical care unit in Ain Shams Hospital, a university-affiliated, tertiary referral center in Cairo, Egypt. Study subjects included 78 patients between August 2017 to August 2018. who required mechanical ventilation ≥72hrs. who fulfilled the spontaneous breath trial (SBT) criteria, at the start of a 1-hr SBT, each hemidiaphragm was evaluated M-mode sonography with the patient in the supine position. Rapid shallow Breathing index (RSBI) was simultaneously calculated at the bedside. Ultrasonographic Diaphragmatic Dysfunction (DD) was diagnosed if an Diaphragmatic Excursion (DE) was &amp;lt;10 mm or negative, the latter indicating paradoxical diaphragmatic movement. Results Diaphragmatic Dysfunction (DD) among the eligible 78 patients was 48% (n = 37). DD group had longer weaning time [39,2 (26-56) hrs. vs. 22.3 (30-16) hrs. p = 0.001) in DD vs. NDD group respectively and total ventilation time [140 (130-150) hrs. vs. 130 (120–140) hrs. p &amp;gt; 0.05) in DD vs. NDD group respectively. Weaning failure was (45.8% vs. 30.8%, p=0.01) in DD vs. NDD group respectively. In NDD group Rt. DE, mean 25.4 ±4.1 mm. While Lt. side was 25.3±4.6 mm, 11.25mm and 22mm (45-15) respectively. In DD group Rt. DE, mean 7.6 ±2.02mm, IQR 2.4 mm and median 8.2mm (10-1.9). While Lt. side was 9.2±0.8mm, 4.3mm and 8.9mm (9.8-5.7) respectively. The area under the receiver operating characteristics curve (ROC) of ultrasonographic criteria in predicting weaning failure was near similar to that of rapid shallow breathing index. Hypercapenic acidosis in NDD group might protect them from VIDD Conclusions DD is present in a significant percentage 48% (nearly half) of our medical ICU patients on MV ≥ 72 hrs which largely account for weaning failure. DD was associated with a significant longer weaning time, and ICU stay, with no significant difference in 30 day mortality Recommendations DE by US measurements is a valuable tool and is recommended as an adjunctive weaning index to aid prediction of weaning outcome. Evaluating the role of spontaneous ventilation modes and advanced ventilation modes as PAV and NAVA effects on decreas ing VIDD versus controlled modes.

The Role of Rapid Shallow Breathing Index in Predicting Successful Weaning of Pediatric Patients with Respiratory Failure

Background About 40 to 60% of all patients admitted to pediatric intensive care unitsundergo mechanical ventilation and 10 to 20% will fail to be extubated. We aimed to determine the role of the rapid shallow breathing index (RSBI) in predicting successful weaning of pediatric patients with respiratory failure. Materials and Methods: This cross-sectional study, was performed on 72 mechanically ventilated children (36 in the lung failure group and 36 in the pump failure group) who were admitted in Tabriz children’s hospital in pediatric intensive care unit (PICU), Tabriz city, Iran. In order to spontaneous breathing trial (SBT) criteria, the patients who had FiO2 less than 40%, PEEP less than or equal to 5 cmH2O and PaO2 higher than 60 mmHg, was placed on spontaneous ventilation mode (PSV+CPAP) to maintain a PEEP of less than or equal to 5 cmH2O, PS of less than or equal to 8 cmH2O and FiO2 of less than or equal to 40%. After 2 hours, measured tidal volume and respiratory rate to calculate the RSBI then the patient was extubated. Results: From 72 patients were enrolled in this study, 26 patients failed in extubation. The total RSBI threshold was 6.7 breath/min/ml/kg (AUC = 0.739, 95%CI = 0.618 – 0.861; p = 0.001)) with a sensitivity of 73.1% and a specificity of 80.4% for success of extubation. Patients successfully extubated had significantly lower RSBI 4.65 ± 3.03 breath/min/ml/kg compared to extubation failuregroup. Conclusion Based on the result of this study, the rapid shallow breathing index with a threshold of 6.7 breath/min/ml/kg was considered to be an acceptable and practical criterion for predicting the outcome of weaning in children.

Xenon anesthesia during the oral cavity sanitation in child with consequences of perinatal brain damage

Halogenated inhalation anesthetics have some adverse effects, including the ability to have a negative effect on the developing brain in children, one of the manifestations of which are cognitive dysfunctions, especially in the younger age group. The article presents a clinical case of xenon in combined inhalation anesthesia in a child with the consequences of perinatal brain damage. During anesthesia, a spontaneous ventilation mode was applied with pressure support ventilation (PSV). There was noted high efficacy and safety xenon anesthesia in a dental treatment, the absence of the effect of anesthesia on cognitive function in a child with a compromised nervous system. It is advisable to further study the use of xenon in the pediatric dentistry anesthesia.

Organ Donation after Circulatory Death in a University Teaching Hospital

Although organ transplantation is well established for end-stage organ failure, many patients die on waiting lists due to insufficient donor numbers. Recently, there has been renewed interest in donation after circulatory death (DCD). In a retrospective observational study we reviewed the screening of patients considered for DCD between March 2007 and December 2012 in our hospital. Overall, 148 patients were screened, 17 of whom were transferred from other hospitals. Ninety-three patients were excluded (53 immediately and 40 after review by donation staff). The 55 DCD patients were younger than those excluded (P=0.007) and they died from hypoxic brain injury (43.6%), intraparenchymal haemorrhage (21.8%) and subarachnoid haemorrhage (14.5%). Antemortem heparin administration and bronchoscopy occurred in 50/53 (94.3%) and 22/55 (40%) of cases, respectively. Forty-eight patients died within 90 minutes and proceeded to donation surgery. Associations with not dying in 90 minutes included spontaneous ventilation mode (P=0.022), absence of noradrenaline infusion (P=0.051) and higher PaO2:FiO2 ratio (P=0.052). The number of brain dead donors did not decrease over the study period. The time interval between admission and death was longer for DCD than for the 45 brain dead donors (5 [3-11] versus 2 [2-3] days; P<0.001), and 95 additional patients received organ transplants due to DCD. Introducing a DCD program can increase potential organ donors without reducing brain dead donors. Antemortem investigations appear to be acceptable to relatives when included in the consent process.

Conservative oxygen therapy in mechanically ventilated patients following cardiac arrest: A retrospective nested cohort study

BackgroundIn mechanically ventilated (MV) cardiac arrest (CA) survivors admitted to the intensive care unit (ICU) avoidance of hypoxia is considered crucial. However, avoidance of hyperoxia may also be important. A conservative approach to oxygen therapy may reduce exposure to both. MethodsWe evaluated the introduction of conservative oxygen therapy (target SpO2 88–92% using the lowest FiO2) during MV for resuscitated CA patients admitted to the ICU. ResultsWe studied 912 arterial blood gas (ABG) datasets: 448 ABGs from 50 ‘conventional’ and 464 ABGs from 50 ‘conservative’ oxygen therapy patients. Compared to the conventional group, conservative group patients had significantly lower PaO2 values and FiO2 exposure (p<0.001, respectively); more received MV in a spontaneous ventilation mode (18% vs 2%; p=0.001) and more were exposed to a FiO2 of 0.21 (19 vs 0 patients, p=0.001). Additionally, according to mean PaO2, more conservative group patients were classified as normoxaemic (36 vs 16 patients, p<0.01) and fewer as hyperoxaemic (14 vs 33 patients, p<0.01). Finally, ICU length of stay was significantly shorter for conservative group patients (p=0.04). There was no difference in the proportion of survivors discharged from hospital with good neurological outcome (14/23 vs 12/22 patients, p=0.67). ConclusionsOur findings provide preliminary support for the feasibility and physiological safety of conservative oxygen therapy in patients admitted to ICU for MV support after cardiac arrest (Trial registration, NCT01684124).

Fibreoptic assessment of laryngeal positioning of the paediatric supraglottic airway device I-Gel

Fibreoptic assessment of laryngeal positioning of the paediatric supraglottic airway device I-Gel

The Risk Factors for Hypoxemia in Children Younger than 5 Years Old Undergoing Rigid Bronchoscopy for Foreign Body Removal

Removal of an airway foreign body (FB) is usually performed by rigid bronchoscopy under general anesthesia, but the choice of anesthesia and ventilation techniques varies greatly among anesthesiologists and institutions. Hypoxemia is the most commonly observed adverse event during rigid bronchoscopy. It is influenced by a variety of factors including the patient's medical condition, the type of surgical procedure, and the anesthetic technique. In the current study, we investigated risk factors that statistically correlate with intraoperative or postoperative hypoxemia in young patients undergoing rigid bronchoscopy. From January 2007 to December 2008, 384 children younger than 5-yr-of-age subjected to rigid bronchoscopy for FB removal were included in the study. The detailed clinical information and perioperative adverse events were recorded. Surgical outcomes and incidence of perioperative adverse events were compared among different ventilation modes (spontaneous ventilation, manual intermittent positive pressure ventilation, and manual jet ventilation) and different anesthetic techniques (total IV anesthesia and inhaled anesthesia). An amalgamated dataset was used for the analysis of factors that correlated with perioperative hypoxemia. In children who received total IV anesthesia with spontaneous ventilation during rigid bronchoscopy, we observed more intraoperative body movement and breath holding, significantly longer duration of emergence from anesthesia, lower percentage of successful FB removal, and more postoperative laryngospasm. Children in the manual jet ventilation group had the least occurrence of intraoperative hypoxemia. Five factors strongly correlated with intraoperative hypoxemia. Younger age, plant seed as the type of FB, longer surgical duration, pneumonia before the procedure, and spontaneous ventilation mode significantly increased the risk of intraoperative hypoxemia, whereas manual jet ventilation mode decreased it. Two factors were associated with postoperative hypoxemia: plant seed as a FB and prolonged duration of emergence from anesthesia. We identified risk factors associated with intraoperative or with postoperative hypoxemia in rigid bronchoscopy which included patient age, type of FB, duration of surgical procedure, pneumonia before the procedure, ventilation mode, and duration of emergence from anesthesia. These results provide evidence that will help clinicians to reduce the incidence of hypoxemia in high-risk children.

Respiratory depression under long-term sedation with sufentanil, midazolam and clonidine has no clinical significance.

Assessment of respiratory depression caused by long-term sedation with sufentanil, midazolam and clonidine. Retrospective assessment using data from a patient data management system. University hospital anaesthesiological ICU. Three hundred ninety-five surgical and trauma patients with an ICU stay of more than 48 h. None. Arterial blood partial pressure of carbon dioxide (PCO2) was evaluated during mechanically assisted spontaneous ventilation (continuous positive airway pressure, synchronised intermittent mandatory ventilation, mandatory minute ventilation, bilevel positive airway pressure). Continuous sedation with sufentanil, midazolam or clonidine or a combination of those drugs was administered to achieve a Ramsay score between 2 and 4. Spontaneously breathing patients without continuous sedation and patients on controlled mechanical ventilation (and sedation) served as control groups. Mean arterial PCO2 from spontaneously breathing patients without continuous sedation was 39.5 +/- 7.3 torr compared with 42.7 +/- 6.8 torr under sufentanil (median 0.44 microg x kg(-1) x h(-1), 98 % of observations between 0.1 and 2.1 microg x kg(-1) x h(-1)), 41.5 +/- 6.1 torr under sufentanil (median 0.90 microg x kg(-1) x h(-1) (0.1-2.8)) plus midazolam (median 45 microg x kg(-1) x h(-1) (7-170)) and 39.8 +/- 5.6 torr under a combination of sufentanil (median 1.15 microg x kg(-1) x h(-1) (0.2-3.6)), midazolam (median 45 microg x kg(-1) x h(-1) (11-216)) and clonidine (median 1.3 microg x kg(-1) x h(-1) (0.2-2.5)). Mean arterial PCO2 from patients on controlled mechanical ventilation was 39.9 +/- 6.1 torr. Patients under continuous sedation with sufentanil exhibit a statistically significant rise in arterial PCO2, however this respiratory depression is only slight and has no clinical significance. Mechanically assisted spontaneous ventilation modes can safely be used under continuous sedation with sufentanil, midazolam or clonidine.

The Ohmeda Universal PAC drawover apparatus. A technical and clinical evaluation.

The Ohmeda Universal PAC drawover apparatus, a modification of an earlier series of vapour-specific vaporizers, was assessed with regard to its output under varying gas flows and temperatures and its clinical usage with isoflurane and enflurane. The device tended to over-deliver vapour, particularly at low flows and at high temperatures. Its clinical performance during spontaneous and positive pressure ventilation was satisfactory, although adequate concentrations were not achieved using enflurane in the spontaneous ventilation mode. The device was not assessed with ether or halothane. The robust construction, relatively large capacity and thermocompensation make it suitable for field or military anaesthesia.