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Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study.

ABSTRACT: Few studies have investigated the measurement of oxygen uptake ([Formula: see text]O₂) in tracheostomized patients undergoing unassisted breathing trials (UBTs) for liberation from mechanical ventilation (MV). Using an open-circuit, breath-to-breath method, we continuously measured [Formula: see text]O₂ and relevant parameters during 120-min UBTs via a T-tube in 49 tracheostomized patients with prolonged MV, and calculated mean values in the first and last 5-min periods. Forty-one (84%) patients successfully completed the UBTs. The median [Formula: see text]O₂ increased significantly (from 235.8 to 298.2 ml/min; P?=?0.025) in the failure group, but there was no significant change in the success group (from 223.1 to 221.6 ml/min; P?=?0.505). In multivariate logistic regression analysis, an increase in [Formula: see text]O₂?>?17% from the beginning period (odds ratio [OR] 0.084; 95% confidence interval [CI] 0.012-0.600; P?=?0.014) and a peak inspiratory pressure greater than -?30 cmH₂O (OR 11.083; 95% CI 1.117-109.944; P?=?0.04) were significantly associated with the success of 120-min UBT. A refined prediction model combining heart rate, energy expenditure, end-tidal CO₂ and oxygen equivalent showed a modest increase in the area under the receiver operating characteristic curve of 0.788 (P?=?0.578) and lower Akaike information criterion score of 41.83 compared to the traditional prediction model including heart rate and respiratory rate for achieving 48 h of unassisted breathing. Our findings show the potential of monitoring [Formula: see text]O₂ in the final phase of weaning in tracheostomized patients with prolonged MV.

SUBMITTER: Lee IH

PROVIDER: S-EPMC7459329 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study.

Lee I-Hsien IH Kuo Yao-Wen YW Lin Feng-Ching FC Wu Chang-Wei CW Jerng Jih-Shuin JS Kuo Ping-Hung PH Cheng Jui-Chen JC Chien Ying-Chun YC Huang Chun-Kai CK Wu Huey-Dong HD

Scientific reports 20200831 1

Few studies have investigated the measurement of oxygen uptake ([Formula: see text]O<sub>2</sub>) in tracheostomized patients undergoing unassisted breathing trials (UBTs) for liberation from mechanical ventilation (MV). Using an open-circuit, breath-to-breath method, we continuously measured [Formula: see text]O<sub>2</sub> and relevant parameters during 120-min UBTs via a T-tube in 49 tracheostomized patients with prolonged MV, and calculated mean values in the first and last 5-min periods. Fo ...[more]

PMID: 32868816

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Project description:Patients requiring prolonged mechanical ventilation (>21 days) are commonly weaned at long-term acute care hospitals (LTACHs). The most effective method of weaning such patients has not been investigated.To compare weaning duration with pressure support vs unassisted breathing through a tracheostomy collar in patients transferred to an LTACH for weaning from prolonged ventilation.Between 2000 and 2010, a randomized study was conducted in tracheotomized patients transferred to a single LTACH for weaning from prolonged ventilation. Of 500 patients who underwent a 5-day screening procedure, 316 did not tolerate the procedure and were randomly assigned to receive weaning with pressure support (n = 155) or a tracheostomy collar (n = 161). Survival at 6- and 12-month time points was also determined.Primary outcome was weaning duration. Secondary outcome was survival at 6 and 12 months after enrollment.Of 316 patients, 4 were withdrawn and not included in analysis. Of 152 patients in the pressure-support group, 68 (44.7%) were weaned; 22 (14.5%) died. Of 160 patients in the tracheostomy collar group, 85 (53.1%) were weaned; 16 (10.0%) died. Median weaning time was shorter with tracheostomy collar use (15 days; interquartile range [IQR], 8-25) than with pressure support (19 days; IQR, 12-31), P = .004. The hazard ratio (HR) for successful weaning rate was higher with tracheostomy collar use than with pressure support (HR, 1.43; 95% CI, 1.03-1.98; P = .033) after adjusting for baseline clinical covariates. Use of the tracheostomy collar achieved faster weaning than did pressure support among patients who did not tolerate the screening procedure between 12 and 120 hours (HR, 3.33; 95% CI, 1.44-7.70; P = .005), whereas weaning time was equivalent with the 2 methods in patients who did not tolerate the screening procedure within 0 to 12 hours. Mortality was equivalent in the pressure-support and tracheostomy collar groups at 6 months (55.92% vs 51.25%; 4.67% difference, 95% CI, -6.4% to 15.7%) and at 12 months (66.45% vs 60.00%; 6.45% difference, 95% CI, -4.2% to 17.1%).Among patients requiring prolonged mechanical ventilation and treated at a single long-term care facility, unassisted breathing through a tracheostomy, compared with pressure support, resulted in shorter median weaning time, although weaning mode had no effect on survival at 6 and 12 months.clinicaltrials.gov Identifier: NCT01541462.

Project description:Although mechanical ventilation is a life-saving intervention in patients suffering from respiratory failure, prolonged mechanical ventilation is often associated with numerous complications including problematic weaning. In contracting skeletal muscle, inadequate oxygen supply can limit oxidative phosphorylation resulting in muscular fatigue. However, whether prolonged mechanical ventilation results in decreased diaphragmatic blood flow and induces an oxygen supply-demand imbalance in the diaphragm remains unknown.We tested the hypothesis that prolonged controlled mechanical ventilation results in a time-dependent reduction in rat diaphragmatic blood flow and microvascular PO2 and that prolonged mechanical ventilation would diminish the diaphragm's ability to increase blood flow in response to muscular contractions.Compared to 30 mins of mechanical ventilation, 6 hrs of mechanical ventilation resulted in a 75% reduction in diaphragm blood flow (via radiolabeled microspheres), which did not occur in the intercostal muscle or high-oxidative hindlimb muscle (e.g., soleus). There was also a time-dependent decline in diaphragm microvascular PO2 (via phosphorescence quenching). Further, contrary to 30 mins of mechanical ventilation, 6 hrs of mechanical ventilation significantly compromised the diaphragm's ability to increase blood flow during electrically-induced contractions, which resulted in a ~80% reduction in diaphragm oxygen uptake. In contrast, 6 hrs of spontaneous breathing in anesthetized animals did not alter diaphragm blood flow or the ability to augment flow during electrically-induced contractions.These new and important findings reveal that prolonged mechanical ventilation results in a time-dependent decrease in the ability of the diaphragm to augment blood flow to match oxygen demand in response to contractile activity and could be a key contributing factor to difficult weaning. Although additional experiments are required to confirm, it is tempting to speculate that this ventilator-induced decline in diaphragmatic oxygenation could promote a hypoxia-induced generation of reactive oxygen species in diaphragm muscle fibers and contribute to ventilator-induced diaphragmatic atrophy and contractile dysfunction.

Project description:ImportanceDaily spontaneous breathing trials (SBTs) are the best approach to determine whether patients are ready for disconnection from mechanical ventilation, but mode and duration of SBT remain controversial.ObjectiveTo evaluate the effect of an SBT consisting of 30 minutes of pressure support ventilation (an approach that is less demanding for patients) vs an SBT consisting of 2 hours of T-piece ventilation (an approach that is more demanding for patients) on rates of successful extubation.Design, setting, and participantsRandomized clinical trial conducted from January 2016 to April 2017 among 1153 adults deemed ready for weaning after at least 24 hours of mechanical ventilation at 18 intensive care units in Spain. Follow-up ended in July 2017.InterventionsPatients were randomized to undergo a 2-hour T-piece SBT (n = 578) or a 30-minute SBT with 8-cm H2O pressure support ventilation (n = 557).Main outcome and measuresThe primary outcome was successful extubation (remaining free of mechanical ventilation 72 hours after first SBT). Secondary outcomes were reintubation among patients extubated after SBT; intensive care unit and hospital lengths of stay; and hospital and 90-day mortality.ResultsAmong 1153 patients who were randomized (mean age, 62.2 [SD, 15.7] years; 428 [37.1%] women), 1018 (88.3%) completed the trial. Successful extubation occurred in 473 patients (82.3%) in the pressure support ventilation group and 428 patients (74.0%) in the T-piece group (difference, 8.2%; 95% CI, 3.4%-13.0%; P = .001). Among secondary outcomes, for the pressure support ventilation group vs the T-piece group, respectively, reintubation was 11.1% vs 11.9% (difference, -0.8%; 95% CI, -4.8% to 3.1%; P = .63), median intensive care unit length of stay was 9 days vs 10 days (mean difference, -0.3 days; 95% CI, -1.7 to 1.1 days; P = .69), median hospital length of stay was 24 days vs 24 days (mean difference, 1.3 days; 95% CI, -2.2 to 4.9 days; P = .45), hospital mortality was 10.4% vs 14.9% (difference, -4.4%; 95% CI, -8.3% to -0.6%; P = .02), and 90-day mortality was 13.2% vs 17.3% (difference, -4.1% [95% CI, -8.2% to 0.01%; P = .04]; hazard ratio, 0.74 [95% CI, 0.55-0.99]).Conclusions and relevanceAmong patients receiving mechanical ventilation, a spontaneous breathing trial consisting of 30 minutes of pressure support ventilation, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. These findings support the use of a shorter, less demanding ventilation strategy for spontaneous breathing trials.Trial registrationClinicalTrials.gov Identifier: NCT02620358.

Project description:BackgroundAn increasing number of patients require prolonged mechanical ventilation (PMV) to survive recovery from critical care. It should be emphasized that PMV is a neglected disease in chest medicine. We investigated 6 years of clinical outcomes and long-term survival rates of patients who required PMV.MethodsWe analyzed retrospectively data from patients in respiratory care center (RCC) to investigate the main causes of respiratory failure leading patients to require PMV. We also studied the factors that influence the ventilator weaned rate, factors that influence the long-term ventilator dependence of patients who require PMV, as well as patients' hospital mortality and long-term survival rates.ResultsA total of 574 patients were admitted to RCC during the 6 years. Of these, 428 patients (74.6%) were older than 65 years. A total of 391 patients (68.1%) were successfully weaned from the ventilator while 83 patients (14.4%) were unsuccessfully weaned. A total of 95 patients (16.6%) died during RCC hospitalization. The most common cause of acute respiratory failure leading to patients requiring PMV was pneumonia. The factor that affected whether patients were successfully weaned from the ventilator was the cause of the respiratory failure that lead patients to require PMV. Our hospital mortality rate was 32.4%; the 1-year survival rate was 24.3%. There was a strong correlation between higher patient age and higher hospital mortality rate and poor 1-year survival rate. Patients with no comorbidity demonstrated good 1-year survival rates. Patients with four comorbidities and patients with end-stage renal disease requiring hemodialysis comorbidity showed poor 1-year survival rates.ConclusionsThe factor that affected whether patients were successfully weaned from the ventilator was the cause of the respiratory failure that lead patients to require PMV. Older patients, patients with renal failure requiring hemodialysis, and those with numerous comorbidities demonstrated poor long-term survival. The reviews of this paper are available via the supplemental material section.

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Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study.

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Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study.

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