Reduced length of intensive care unit stay and early mechanical ventilator weaning with enhanced recovery after surgery (ERAS) in free fibula flap surgery.

This study aimed to evaluate the effects of the enhanced recovery after surgery (ERAS) program on postoperative recovery of patients who underwent free fibula flap surgery for mandibular reconstruction. This retrospective study included 188 patients who underwent free fibula flap surgery for complex mandibular and soft tissue defects between January 2011 and December 2022. We divided them into two groups: the ERAS group, consisting of 36 patients who were treated according to the ERAS program introduced from 2021 to 2022. Propensity score matching was used for the non-ERAS group, which comprised 36 cases selected from 152 patients between 2011 and 2020, based on age, sex, and smoking history. After propensity score matching, the ERAS and non-ERAS groups included 36 patients each. The primary outcome was the length of intensive care unit (ICU) stay; the secondary outcomes were flap complications, unplanned reoperation, 30-day readmission, postoperative ventilator use length, surgical site infections, incidence of delirium within ICU, lower-limb comorbidities, and morbidity parameters. There were no significant differences in the demographic characteristics of the patients. However, the ERAS group showed the lower length of intensive care unit stay (ERAS vs non-ERAS: 8.66 ± 3.90 days vs. 11.64 ± 5.42 days, P = 0.003) and post-operative ventilator use days (ERAS vs non-ERAS: 1.08 ± 0.28 days vs. 2.03 ± 1.05 days, P < 0.001). Other secondary outcomes were not significantly different between the two groups. Additionally, patients in the ERAS group had lower postoperative morbidity parameters, such as postoperative nausea, vomiting, urinary tract infections, and pulmonary complications (P = 0.042). The ERAS program could be beneficial and safe for patients undergoing free fibula flap surgery for mandibular reconstruction, thereby improving their recovery and not increasing flap complications and 30-day readmission.

Weaning and extubation failure in myasthenic crisis: a multicenter analysis.

Myasthenic crisis (MC) requiring mechanical ventilation is a serious complication of myasthenia gravis (MG). Here we analyze the frequency and risk factors of weaning- and extubation failure as well as its impact on the clinical course in a large cohort. We performed a retrospective chart review on patients treated for MC in 12 German neurological departments between 2006 and 2015. Weaning failure (WF) was defined as negative spontaneous breathing trial, primary tracheostomy, or extubation failure (EF) (reintubation or death). WF occurred in 138 episodes (64.2%). Older Age (p = 0.039), multiple comorbidities (≥ 3) (p = 0.007, OR = 4.04), late-onset MG (p = 0.004, OR = 2.84), complications like atelectasis (p = 0.008, OR = 3.40), pneumonia (p < 0.0001, OR = 3.45), cardio-pulmonary resuscitation (p = 0.005, OR = 5.00) and sepsis (p = 0.02, OR = 2.57) were associated with WF. WF occurred often in patients treated with intravenous immungloblins (IVIG) (p = 0.002, OR = 2.53), whereas WF was less often under first-line therapy with plasma exchange or immunoadsorption (p = 0.07, OR = 0.57). EF was observed in 58 of 135 episodes (43.0%) after first extubation attempt and was related with prolonged mechanical ventilation, intensive care unit stay and hospital stay (p ≤ 0.0001 for all). Extubation success was most likely in a time window for extubation between day 7 and 12 after intubation (p = 0.06, OR = 2.12). We conclude that WF and EF occur very often in MC and are associated with poor outcome. Older age, multiple comorbidities and development of cardiac and pulmonary complications are associated with a higher risk of WF and EF. Our data suggest that WF occurs less frequently under first-line plasma exchange/immunoadsorption compared with first-line use of IVIG.

Predictors of in-hospital mortality after successful weaning of venoarterial extracorporeal membrane oxygenation in cardiogenic shock.

Limited knowledge exists regarding the predictors of mortality after successful weaning of venoarterial extracorporeal membrane oxygenation (ECMO). We aimed to identify predictors of in-hospital mortality in patients with cardiogenic shock (CS) after successful weaning from ECMO. Data were obtained from a multicenter registry of CS. Successful ECMO weaning was defined as survival with minimal mean arterial pressure (> 65 mmHg) for > 24 h after ECMO removal. The primary outcome was in-hospital mortality after successful ECMO weaning. Among 1247 patients with CS, 485 received ECMO, and 262 were successfully weaned from ECMO. In-hospital mortality occurred in 48 patients (18.3%). Survivors at discharge differed significantly from non-survivors in age, cardiovascular comorbidities, cause of CS, left ventricular ejection fraction, and use of adjunctive therapy. Five independent predictors for in-hospital mortality were identified: use of continuous renal replacement therapy (odds ratio 5.429, 95% confidence interval [CI] 2.468-11.940; p < 0.001), use of intra-aortic balloon pump (3.204, 1.105-9.287; p = 0.032), diabetes mellitus (3.152, 1.414-7.023; p = 0.005), age (1.050, 1.016-1.084; p = 0.003), and left ventricular ejection fraction after ECMO insertion (0.957, 0.927-0.987; p = 0.006). Even after successful weaning of ECMO, patients with irreversible risk factors should be recognized, and careful monitoring should be done for sign of deconditioning.

Managing respiratory muscle weakness during weaning from invasive ventilation.

Weaning is a critical stage of an intensive care unit (ICU) stay, in which the respiratory muscles play a major role. Weakness of the respiratory muscles, which is associated with significant morbidity in the ICU, is not limited to atrophy and subsequent dysfunction of the diaphragm; the extradiaphragmatic inspiratory and expiratory muscles also play important parts. In addition to the well-established deleterious effect of mechanical ventilation on the respiratory muscles, other risk factors such as sepsis may be involved. Weakness of the respiratory muscles can be suspected visually in a patient with paradoxical movement of the abdominal compartment. Measurement of maximal inspiratory pressure is the simplest way to assess respiratory muscle function, but it does not specifically take the diaphragm into account. A cut-off value of -30 cmH2O could identify patients at risk for prolonged ventilatory weaning; however, ultrasound may be better for assessing respiratory muscle function in the ICU. Although diaphragm dysfunction has been associated with weaning failure, this diagnosis should not discourage clinicians from performing spontaneous breathing trials and considering extubation. Recent therapeutic developments aimed at preserving or restoring respiratory muscle function are promising.

Underweight predicts extubation failure after planned extubation in intensive care units.

BACKGROUND: Body weight is associated with different physiological changes and the association between weight and mortality in critical care setting had been discussed before. In this study, we investigated the linkage between underweight and post-extubation failure in mechanical ventilated patients in critical setting. METHODS: This is a retrospective cohort study including patients who were admitted to medical or surgical intensive care units (ICU) between June 2016 and July 2018 and had received endotracheal intubation for more than 72 hours. Those who passed spontaneous breathing trial and underwent a planned extubation were enrolled. Extubation failure was defined as those who required reintubation within the first 72 hours for any reasons. The probability of extubation failure was calculated. Demographic and clinical characteristics were recorded. Multivariate logistic regression models were then used to determine the potential risk factors associated with extubation failure. RESULTS: Overall, 268 patients met the inclusion criteria and were enrolled in our study for analysis. The median age of included patients was 67 years (interquartile range, 55-80 years) with 65.3% being male; 63.1% of the patients were included from medical ICU. The proportion of extubation failure in our cohort was 7.1% (19/268; 95% confidence interval [CI], 4.3-10.9%). Overall, underweight patients had the highest risk of extubation failure (8/50), as compared with normoweight (9/135) and overweight patients (2/83). In the multivariate analysis, being underweight (adjust OR [aOR], 3.80, compared to normoweight; 95% CI, 1.23-11.7) and lower maximal inspiratory airway pressure (aOR per one cmH2O decrease, 1.05; 95% CI 1.00-1.09) remained significantly associated with extubation failure. CONCLUSION: In our study, being underweight and lower maximal inspiratory airway pressure was associated with post-extubation respiratory failure after a planned extubation.

Spontaneous-Breathing Trials with Pressure-Support Ventilation or a T-Piece.

BACKGROUND: Spontaneous-breathing trials can be performed with the use of either pressure-support ventilation (PSV) or a T-piece. Whether PSV trials may result in a shorter time to tracheal extubation than T-piece trials, without resulting in a higher risk of reintubation, among patients who have a high risk of extubation failure is unknown. METHODS: In this multicenter, open-label trial, we randomly assigned patients who had a high risk of extubation failure (i.e., were >65 years of age or had an underlying chronic cardiac or respiratory disease) to undergo spontaneous-breathing trials performed with the use of either PSV (with a pressure-support level of 8 cm of water and no positive end-expiratory pressure) or a T-piece. The primary outcome was the total time without exposure to invasive ventilation (reported as the number of ventilator-free days) at day 28 after the initial spontaneous-breathing trial. Secondary outcomes included extubation within 24 hours and extubation within 7 days after the initial spontaneous-breathing trial, as well as reintubation within 7 days after extubation. RESULTS: A total of 969 patients (484 in the PSV group and 485 in the T-piece group) were included in the analysis. At day 28, the median number of ventilator-free days was 27 (interquartile range, 24 to 27) in the PSV group and 27 (interquartile range, 23 to 27) in the T-piece group (difference, 0 days; 95% confidence interval [CI], -0.5 to 1; P = 0.31). Extubation was performed within 24 hours in 376 patients (77.7%) in the PSV group and in 350 patients (72.2%) in the T-piece group (difference, 5.5 percentage points; 95% CI, 0.01 to 10.9), and extubation was performed within 7 days in 473 patients (97.7%) and 458 patients (94.4%), respectively (difference, 3.3 percentage points; 95% CI, 0.8 to 5.9). Reintubation was performed in 72 of 481 patients (14.9%) in the PSV group and in 65 of 477 patients (13.6%) in the T-piece group (difference, 1.3 percentage points; 95% CI, -3.1 to 5.8). Cardiac or respiratory arrest was a reason for reintubation in 9 patients (3 in the PSV group and 6 in the T-piece group). CONCLUSIONS: Among patients who had a high risk of extubation failure, spontaneous-breathing trials performed with PSV did not result in significantly more ventilator-free days at day 28 than spontaneous-breathing trials performed with a T-piece. (Supported by the French Ministry of Health; TIP-EX ClinicalTrials.gov number, NCT04227639.).

The weaning from mechanical ventilation: a comprehensive ultrasound approach.

PURPOSE OF REVIEW: Due to heart, lung and diaphragm interactions during weaning from mechanical ventilation, an ultrasound integrated approach may be useful in the detection of dysfunctions potentially leading to weaning failure. In this review, we will summarize the most recent advances concerning the ultrasound applications relevant to the weaning from mechanical ventilation. RECENT FINDINGS: The role of ultrasonographic examination of heart, lung and diaphragm has been deeply investigated over the years. Most recent findings concern the ability of lung ultrasound in detecting weaning induced pulmonary edema during spontaneous breathing trial. Furthermore, in patients at high risk of cardiac impairments, global and anterolateral lung ultrasound scores have been correlated with weaning and extubation failure, whereas echocardiographic indexes were not. For diaphragmatic ultrasound evaluation, new indexes have been proposed for the evaluation of diaphragm performance during weaning, but further studies are needed to validate these results. SUMMARY: The present review summarizes the potential role of ultrasonography in the weaning process. A multimodal integrated approach allows the clinician to comprehend the pathophysiological processes of weaning failure.

Diaphragmatic electromyography during a spontaneous breathing trial to predict extubation failure in preterm infants.

BACKGROUND: Premature attempts at extubation and prolonged episodes of ventilatory support in preterm infants have adverse outcomes. The aim of this study was to determine whether measuring the electrical activity of the diaphragm during a spontaneous breathing trial (SBT) could predict extubation failure in preterm infants. METHODS: When infants were ready for extubation, the electrical activity of the diaphragm was measured by transcutaneous electromyography (EMG) before and during a SBT when the infants were on endotracheal continuous positive airway pressure. RESULTS: Forty-eight infants were recruited (median (IQR) gestational age of 27.2 (25.6-30.4) weeks). Three infants did not pass the SBT and 13 failed extubation. The amplitude of the EMG increased during the SBT [2.3 (1.5-4.2) versus 3.5 (2.1-5.3) µV; p < 0.001]. In the whole cohort, postmenstrual age (PMA) was the strongest predictor for extubation failure (area under the curve (AUC) 0.77). In infants of gestational age <29 weeks, the percentage change of the EMG predicted extubation failure with an AUC of 0.74 while PMA was not associated with the outcome of extubation. CONCLUSIONS: In all preterm infants, PMA was the strongest predictor of extubation failure; in those born <29 weeks of gestation, diaphragmatic electromyography during an SBT was the best predictor of extubation failure. IMPACT: Composite assessments of readiness for extubation may be beneficial in the preterm population. Diaphragmatic electromyography measured by surface electrodes is a non-invasive technique to assess the electrical activity of the diaphragm. Postmenstrual age was the strongest predictor of extubation outcome in preterm infants. The change in diaphragmatic activity during a spontaneous breathing trial in extremely prematurely born infants can predict subsequent extubation failure with moderate sensitivity and specificity.

Predictive Factors of Extubation Failure in COVID-19 Mechanically Ventilated Patients.

Purpose: We investigated whether COVID-19 patients on mechanical ventilation (MV) had a different extubation outcome compared to non-COVID-19 patients while identifying predictive factors of extubation failure in the former. Methods: A retrospective, single-center, and observational study was done on 216 COVID-19 patients admitted to an intensive care unit (ICU) between March 2020 and March 2021, aged ≥ 18 years, in use of invasive MV for more than 24 h, which progressed to weaning. The primary outcome that was evaluated was extubation failure during ICU stay. A statistical analysis was performed to evaluate the association of patient characteristics with extubation outcome, and a Poisson regression model determined the predictive value. Results: Seventy-seven patients were extubated; the mean age was 57.2 years, 52.5% were male, and their mean APACHE II score at admission was 17.8. On average, MV duration until extubation was 8.7 ± 3.7 days, with 14.9 ± 10.1 days of ICU stay and 24.6 ± 14.0 days with COVID-19 symptoms. The rate of extubation failure (ie, the patient had to be reintubated during their ICU stay) was 22.1% (n = 17), while extubation was successful in 77.9% (n = 60) of cases. Failure was observed in only 7.8% of cases when evaluated 48 hours after extubation. The mean reintubation time was 4.28 days. After adjusting the analysis for age, sex, during of symptoms, days under MV, dialysis, and PaO2/FiO2 ratio, some parameters independently predicted extubation failure: age ≥ 66 years (APR = 5.12 [1.35-19.46]; p = 0.016), ≥ 31 days of symptoms (APR = 5.45 [0.48-62.19]; p = 0.016), and need for dialysis (APR = 5.10 [2.00-13.00]; p = 0.001), while a PaO2/FiO2 ratio >300 decreased the probability of extubation failure (APR = 0.14 [0.04-0.55]; p = 0.005). The presence of three predictors (ie, age ≥ 66 years, time of symptoms ≥ 31 days, need of dialysis, and PaO2/FiO2 ratio < 200) increased the risk of extubation failure by a factor of 23.0 (95% CI, 3.34-158.5). Conclusion: COVID-19 patients had an extubation failure risk that was almost three times higher than non-COVID-19 patients, with the extubation of the former being delayed compared to the latter. Furthermore, an age ≥ 66 years, time of symptoms ≥ 31 days, need of dialysis, and PaO2/FiO2 ratio > 200 were independent predictors for extubation failure, and the presence of three of these characteristics increased the risk of failure by a factor of 23.0.

Association of baseline diaphragm, rectus femoris and vastus intermedius muscle thickness with weaning from mechanical ventilation.

BACKGROUND: To determine whether baseline diaphragm (Tdi), rectus femoris (RF) and vastus intermedius (VI) muscle thickness (TRF and TRF + VI) are associated with weaning success. MATERIAL AND METHODS: Right Tdi, TRF and TRF + VI were measured by ultrasonography within 36 h of intubation and diaphragmatic excursion (DE) was evaluated at the first spontaneous breathing trial in adult critically-ill patients. Reintubation or death within 7 days after extubation was defined as weaning failure. Weaning failure and success groups were compared in terms of ultrasonographic measurements and clinical features. RESULTS: Thirty-eight patients were assessed for weaning, 15 (39.4%) being in the weaning failure group. The median body mass index (BMI) was lower while the median clinical frailty scale (CFS), vasopressor use, duration of mechanical ventilation, intensive care and hospital mortality rate were higher in the weaning failure group, and the median TRF + VI (14.0 [12.3-26.2] vs 23.6 [21.3-27.1] mm, p = 0.03) and median DE (19.4 [14.6-24.0] vs 25.9 [19.3-38.5] mm, p = 0.045) were lower. The median Tdi was similar in two groups (1.9 [1.5-2.3] vs 2.0 [1.7-2.4] mm, p = 0.26). In ROC analysis, area under the curve for TRF + VI was 0.71 (95% CI: 0.51-0.90; p = 0.035), with 21 mm cut-off having sensitivity of 82% and specificity of 57%. Binary logistic regression analysis revealed TRF + VI < 21 mm as the only predictor of weaning failure with an odds ratio of 10.5 (95% CI: 1.1-97.8, p = 0.038) after adjusting for age, sex, BMI and CFS. CONCLUSIONS: TRF + VI lower than 21 mm, measured by ultrasonography within 36 h of intubation, was associated with weaning failure among critically-ill patients.

Prediction of successful de-cannulation of tracheostomised patients in medical intensive care units.

BACKGROUND: Limited data are available on practical predictors of successful de-cannulation among the patients who undergo tracheostomies. We evaluated factors associated with failed de-cannulations to develop a prediction model that could be easily be used at the time of weaning from MV. METHODS: In a retrospective cohort of 346 tracheostomised patients managed by a standardized de-cannulation program, multivariable logistic regression analysis identified variables that were independently associated with failed de-cannulation. Based on the logistic regression analysis, the new predictive scoring system for successful de-cannulation, referred to as the DECAN score, was developed and then internally validated. RESULTS: The model included age > 67 years, body mass index < 22 kg/m2, underlying malignancy, non-respiratory causes of mechanical ventilation (MV), presence of neurologic disease, vasopressor requirement, and presence of post-tracheostomy pneumonia, presence of delirium. The DECAN score was associated with good calibration (goodness-of-fit, 0.6477) and discrimination outcomes (area under the receiver operating characteristic curve 0.890, 95% CI 0.853-0.921). The optimal cut-off point for the DECAN score for the prediction of the successful de-cannulation was ≤ 5 points, and was associated with the specificities of 84.6% (95% CI 77.7-90.0) and sensitivities of 80.2% (95% CI 73.9-85.5). CONCLUSIONS: The DECAN score for tracheostomised patients who are successfully weaned from prolonged MV can be computed at the time of weaning to assess the probability of de-cannulation based on readily available variables.

La ventilación mecánica no invasiva en los servicios de urgencias / Noninvasive mechanical ventilation in emergency departments

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Factores predictivos de fracaso en el destete de la ventilación mecánica no invasiva en urgencias / Predictors of noninvasive mechanical ventilation weaning failure in the emergency department

OBJETIVOS: Analizar los factores predictivos del fracaso del destete en los pacientes sometidos a ventilación mecánica no invasiva (VMNI) en un servicio de urgencias hospitalario (SUH). MÉTODO: Estudio observacional de cohortes prospectivo con muestreo consecutivo de los pacientes que precisaron VMNI durante la atención en el SUH. Se estableció como variable dependiente el fracaso del destete de la VMNI, definido comola necesidad de reiniciar o instaurar la VMNI durante el mismo ingreso hospitalario tras el primer intento de destete. RESULTADOS: Del total de 675 pacientes elegibles, se incluyeron 360 pacientes (53,4%). Se excluyeron 100 (31,7%),58 (18,4%) y 157 (49,9%) por VMNI domiciliaria, fracaso previo al intento de destete y por realización del intento de destete fuera del SUH, respectivamente. Sesenta y dos casos (17,3%) presentaron con fracaso del destete de la VMNI. Los factores independientes asociados al fracaso del destete fueron la concentración de bicarbonato antes del destete (ORa: 1,06; IC 95%: 1,01-1,12; p = 0,014), la duración VMNI en horas (ORa: 1,10; IC 95%: 1,04-1,16; p < 0,001) yun pH < 7,35 antes del destete (ORa: 2,48; IC: 1,16-5,31; p = 0,019). CONCLUSIÓN: El fracaso del destete de la VMNI en el SUH ocurrió en un 17% de los casos. La duración de la técnica, elvalor del HCO3- y el pH < 7,35 antes del destete fueron factores independientes asociados al fracaso

OBJETIVES: To analyze factors related to the failure of noninvasive mechanical ventilation (NIV) weaning in a hospital emergency department (ED). METHODS: Prospective, observational cohort study with enrolled a sample of consecutive patients who required NIV during ED care. The dependent variable was NIV weaning failure, defined by the need to restart NIV in the ED after a first attempt to withdraw the respirator. RESULTS: Of a total of 675 candidates, we included 360 patients (53.4%). Exclusions were 100 patients (31.7%) who were on NIV at home; 58 (18.4%) in whom NIV initially failed; and 157 (49.9%) in whom weaning was attempted outside the ED. Seventy-two (17.3%) cases of weaning failure in the ED were observed. Factors independently associated with failure were the bicarbonate (HCO3) concentrations before attempted weaning (adjusted odds ratio [aOR], 1.06; 95% CI, 1.01-1.12;P = .014), time on NIV in hours (aOR, 1.10; 95% CI, 1.04-1.16;P < .001), and a pH less than 7.35 before weaning (aOR, 2.48; 95% CI, 1.16-5.31;P = .019). CONCLUSIONS: Weaning failure occurs in 17% of ED patients on NIV. Time on NIV, HCO3 concentration, and a pH less than 7.35 before weaning are independently associated with failure to wean from the respirator

Diaphragm Ultrasound in Weaning From Mechanical Ventilation.

A 65-year-old man was admitted to the ICU for septic shock due to pneumonia. He remained on mechanical ventilation for 96 hours. His shock resolved, and he no longer required IV vasopressor therapy. His vital signs included a BP of 105/70 mm Hg, heart rate 85 beats/min, respiratory rate 22 breaths/min, and oxygen saturation 95%. His ventilator settings were volume control/assist control with a positive end-expiratory pressure of 5 and an Fio2 set to 40%. On these setting his blood gas showed an Pao2 of 75 mm Hg. He was following simple commands and had minimal tracheobronchial secretions. He was placed on a spontaneous breathing trial with a spontaneous mode of ventilation and pressure support of 7/5. He remained hemodynamically stable and showed no distress through the procedure, so he was extubated to 6 L oxygen by nasal cannula. Eighteen hours later, the patient was found to have increased work of breathing, with use of accessory respiratory muscles. A blood gas showed an elevated level of CO2, so the patient was reintubated. After intubation, the patient again appeared comfortable on minimal ventilator settings. Chest radiography before reintubation showed no new parenchymal process, but an elevated left diaphragm. After a thorough workup, it was determined that diaphragmatic weakness was the most likely reason for respiratory failure. The team questioned whether there was a way to have detected this before extubation.

Does Standard Physical Therapy Increase Quadriceps Strength in Chronically Ventilated Patients? A Pilot Study.

OBJECTIVES: Physical therapy is standard care for mechanically ventilated patients, but there is no evidence, using nonvolitional, objective measurements, that physical therapy increases muscle strength in this population. The present study tested the hypothesis that 2 weeks of standard, conventional physical therapy provided at a ventilator weaning facility would increase quadriceps strength in mechanically ventilated patients. DESIGN: Prospective observational study. SETTING: Ventilator weaning unit. PATIENTS: Patients who were transferred from an acute care hospital because of failure to wean from mechanical ventilation and who were receiving physical therapy as prescribed by facility staff. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We employed a novel, nonvolitional objective technique, quadriceps twitch force generation in response to femoral nerve magnetic stimulation, to assess leg strength before and after 2 weeks of conventional physical therapy. The duration and specific exercises provided to patients were also recorded. In a subset of patients, we measured muscle activation intensity using wireless electromyogram recordings. Indices of respiratory function (maximum inspiratory pressure generation and the rapid shallow breathing index) were also assessed. Patients' responses to 2 weeks of physical therapy were poor; on average, quadriceps twitch fell by -1.02 ± 0.71 Newtons. Neither physical therapy duration nor specific forms of exercise were identified to positively impact quadriceps twitch. Electromyogram recordings indicated that during training, muscle activation was poor. Consequently, therapists spent substantial time performing exercises that elicited little muscle activation. Physical therapy did not improve respiratory function. CONCLUSIONS: Standard physical therapy delivered in a ventilator weaning facility failed to improve quadriceps leg strength in a majority of mechanically ventilated patients. The fact that mechanically ventilated patients fail to achieve high levels of muscle activation during physical therapy provides a potential explanation as to why physical therapy may often be ineffective. We speculate that use of novel methods which increase muscle activation during exercise may improve responses of mechanically ventilated patients to physical therapy.

Maximal expiratory pressure is associated with reinstitution of mechanical ventilation after successful unassisted breathing trials in tracheostomized patients with prolonged mechanical ventilation.

OBJECTIVE: Reinstitution of mechanical ventilation (MV) for tracheostomized patients after successful weaning may occur as the care setting changes from critical care to general care. We aimed to investigate the occurrence, consequence and associated factors of MV reinstitution. METHODS: We analyzed the clinical data and physiological measurements of tracheostomized patients with prolonged MV discharged from the weaning unit to general wards after successful weaning to compare between those with and without in-hospital MV reinstitution within 60 days. RESULTS: Of 454 patients successfully weaned, 116 (25.6%) reinstituted MV at general wards within 60 days; at hospital discharge, 42 (36.2%) of them were eventually liberated from MV, 51 (44.0%) remained MV dependent, and 33 (28.4%) died. Of the 338 patients without reinstitution within 60 days, only 3 (0.9%) were later reinstituted with MV before discharge (on day 67, 89 and 136 at general wards, respectively), and 322 (95.2%) were successfully weaned again at discharge, while 13 (3.8%) died. Patients with MV reinstitution had a significantly lower level of maximal expiratory pressure (PEmax) before unassisted breathing trial compared to those without reinstitution. Multivariable Cox regression analysis showed fever at RCC discharge (hazard ratio [HR] 14.00, 95% confidence interval [CI] 3.2-61.9) chronic obstructive pulmonary disease (HR 2.37, 95% CI 1.34-4.18), renal replacement therapy at the ICU (HR 2.29, 95% CI 1.50-3.49) and extubation failure before tracheostomy (HR 1.76, 95% CI 1.18-2.63) were associated with increased risks of reinstitution, while PEmax > 30 cmH2O (HR 0.51, 95% CI 0.35-0.76) was associated with a decreased risk of reinstitution. CONCLUSIONS: The reinstitution of MV at the general ward is significant, with poor outcomes. The PEmax measured before unassisted breathing trial was significantly associated with the risk of reinstituting MV at the general wards.

Pre-extubation functional residual capacity and risk of extubation failure among patients with hypoxemic respiratory failure.

Hypoxemic respiratory failure is usually accompanied with a certain extent of consolidation and alveolar derecruitment, which may still be present even after the patients have achieved the status of readiness to extubate. Functional residual capacity (FRC) is an indicator of lung aeration. This study aimed to evaluate whether pre-extubation FRC is associated with the risk of extubation failure in patients with hypoxemic respiratory failure. We prospectively included 92 patients intubated for hypoxemic respiratory failure. We used a technique based on a nitrogen multiple breath washout method to measure FRC before the planned extubation. The median FRC before extubation was 25 mL/kg (Interquartile range, 20-32 mL/Kg) per predicted body weight (pBW). After extubation, 20 patients (21.7%) were reintubated within 48 hours. The median FRC was higher in the extubation success group than in the extubation failure group (27 versus 21 mL/Kg, p < 0.001). Reduced FRC was associated with higher risk of extubation failure (odds ratio, 1.14 per each decreased of 1 mL/Kg of FRC/pBW, 95% CI, 1.05-1.23, p = 0.002). In conclusion, pre-extubation FRC is associated with the risk of extubation failure. Reduced FRC may be incorporated into the traditional risk factors to identify patients at high risk for extubation failure.

Decreases in Mixed Venous Blood O2 Saturation in Cardiac Surgery Patients Following Extubation.

BACKGROUND: Decreases in mixed venous O2 saturation (SvO2) have been reported to occur in postcardiac surgery patients during weaning from mechanical ventilation. Our aim was to establish whether the physiological mechanism responsible for this phenomenon was a decrease in systemic O2 delivery (DO2) or an increase in global O2 consumption (V˙ O 2). METHODS: We studied 21 mechanically ventilated, postoperative cardiac patients for 30 minutes before and 60 minutes after extubation. We monitored continuously arterial O2 saturation by pulse oximetry (SaO2) and central venous O2 saturation (ScvO2) with an oximetry catheter. Mixed venous O2 saturation (SvO2) and cardiac output were also measured continuously with an oximetry pulmonary artery catheter. Systemic O2 delivery and V˙ O 2 were calculated according to accepted formulae. RESULTS: Immediately following extubation, ScvO2 and SvO2 decreased rapidly (P < .01). Systemic O2 consumption increased from 65 (57) mL·min-1 to 194 (66) mL·min-1 (P < .05) with no changes in DO2. Consequently, systemic O2 extraction rose from 38% (8%) to 45% (9%; P < .01). Preoperative left ventricular ejection fraction correlated with the decline in SvO2 postextubation. All patients weaned successfully. CONCLUSIONS: Decreases in SvO2 after discontinuation of ventilatory support in postcardiac surgery patients occur as V˙ O 2 increases in response to greater energy requirements by muscles of ventilation that are not initially matched by increases in DO2.