The pulmonary physician in critical care. 10: difficult weaning

Occurrence of Dysrhythmias During Ventilatory Weaning and Its Association With Length of Mechanical Ventilation and In-hospital Complications

BACKGROUND

The occurrence of cardiac dysrhythmias during ventilatory weaning and its impact on the length of ventilation and occurrence of complications have not been systematically investigated.

OBJECTIVES

The aim of this study was to evaluate the association between cardiac dysrhythmias during weaning and the duration of ventilation and complications during ventilator weaning.

METHOD

Data on the length of ventilation and complications were collected from the medical records of 30 mechanically ventilated patients. Continuous electrocardiographic recordings were collected at baseline and during the initial weaning trial. Multiple regression analysis was used to evaluate the association between dysrhythmias and length of ventilation. The relationship between prolonged ventilation and complications was assessed using the χ2 analysis.

RESULTS

Supraventricular ectopic beats during weaning positively predicted the length of ventilation (P < .01). Prolonged ventilation (>7 days) is associated with the occurrence of renal insufficiency and septicemia.

CONCLUSION

The association between the occurrence of supraventricular ectopic beats during ventilator weaning and the length of ventilation requires further evaluation and tailored management to improve patient outcomes.

An artificial intelligence system to predict the optimal timing for mechanical ventilation weaning for intensive care unit patients: A two-stage prediction approach

Background

For the intensivists, accurate assessment of the ideal timing for successful weaning from the mechanical ventilation (MV) in the intensive care unit (ICU) is very challenging.

Purpose

Using artificial intelligence (AI) approach to build two-stage predictive models, namely, the try-weaning stage and weaning MV stage to determine the optimal timing of weaning from MV for ICU intubated patients, and implement into practice for assisting clinical decision making.

Methods

AI and machine learning (ML) technologies were used to establish the predictive models in the stages. Each stage comprised 11 prediction time points with 11 prediction models. Twenty-five features were used for the first-stage models while 20 features were used for the second-stage models. The optimal models for each time point were selected for further practical implementation in a digital dashboard style. Seven machine learning algorithms including Logistic Regression (LR), Random Forest (RF), Support Vector Machines (SVM), K Nearest Neighbor (KNN), lightGBM, XGBoost, and Multilayer Perception (MLP) were used. The electronic medical records of the intubated ICU patients of Chi Mei Medical Center (CMMC) from 2016 to 2019 were included for modeling. Models with the highest area under the receiver operating characteristic curve (AUC) were regarded as optimal models and used to develop the prediction system accordingly.

Results

A total of 5,873 cases were included in machine learning modeling for Stage 1 with the AUCs of optimal models ranging from 0.843 to 0.953. Further, 4,172 cases were included for Stage 2 with the AUCs of optimal models ranging from 0.889 to 0.944. A prediction system (dashboard) with the optimal models of the two stages was developed and deployed in the ICU setting. Respiratory care members expressed high recognition of the AI dashboard assisting ventilator weaning decisions. Also, the impact analysis of with- and without-AI assistance revealed that our AI models could shorten the patients' intubation time by 21 hours, besides gaining the benefit of substantial consistency between these two decision-making strategies.

Conclusion

We noticed that the two-stage AI prediction models could effectively and precisely predict the optimal timing to wean intubated patients in the ICU from ventilator use. This could reduce patient discomfort, improve medical quality, and lower medical costs. This AI-assisted prediction system is beneficial for clinicians to cope with a high demand for ventilators during the COVID-19 pandemic.

Surgery and perioperative management for post-intubation tracheoesophageal fistula: case series analysis

BACKGROUND

Post-intubation tracheoesophageal fistula (PITEF) is an often mistreated, severe condition. This case series reviewed for both the choice and timing of surgical technique and outcome PITEF patients.

METHODS

This case series reviewed ten consecutive patients who had undergone esophageal defect repair and airway resection/reconstruction between 2000 and 2014. All cases were examined for patients: general condition, medical history, preparation to surgery, diagnostic work-up, timing of surgery and procedure, fistula size and site, ventilation type, nutrition, post-operative course and complications.

RESULTS

All patients were treated according to Grillo's technique. Overall, 6/10 patients had undergone a preliminary period of medical preparation. Additionally, 3 patients had already had a tracheostomy, one had had a gastrostomy and 4 had both. One patient had a Dumon stent with enlargement of the fistula. Concomitant tracheal stenosis had been found in 7 patients. The mean length of the fistulas was 20.5 mm (median 17.5 mm; range, 8-45 mm), at a median distance from the glottis of 43 mm (range, 20-68 mm). Tracheal resection was performed in all ten cases. The fistula was included in the resection in 6 patients, while it was excluded in the remaining 4 due to their distance. Post-repair tracheotomy was performed in 3 patients. The procedure was performed in 2 ventilated patients. Morbidity related to fistula and anastomosis was recorded in 3 patients (30%), with one postoperative death (10%); T-Tube placement was necessary in 3 patients, with 2/3 decannulations after long-stenting. Definitive PITEF closure was obtained for all patients. At 5-year follow-up, the 9 surviving patients had no fistula-related morbidity.

CONCLUSIONS

Primary esophageal closure with tracheal resection/reconstruction seemed to be effective treatment both short and long-term. Systemic conditions, mechanical ventilation, detailed preoperative assessment and appropriate preparation were associated with outcome. Indeed, the 3 patients who had received T-Tube recovered from anastomotic complications.

The Care-Integrated Concentration Meditation Program for Patients With Weaning Difficulty: A Pilot Study

Because of the multifaceted process of weaning patients with prolonged mechanical ventilation, enhancing weaning success remains a challenge. The Care-Integrated Concentration Meditation Program was developed on the basis of Buddhist philosophy and implemented to determine its procedural feasibility. A qualitative case study with 3 participants was conducted, and the process and initial outcomes were evaluated.

Mechanisms of ventilator dependence in children with neuromuscular and respiratory control disorders identified by monitoring diaphragm electrical activity

OBJECTIVES

To report on the monitoring of diaphragm electrical activity (Edi) using neurally adjusted ventilator assist (NAVA) technology to investigate the mechanisms of ventilator dependence in children with neuromuscular and respiratory control disorders.

PATIENTS AND METHODS

Using NAVA technology, electrical activity of the diaphragm (Edi) was monitored at the lowest achievable level of respiratory support in six ventilator-dependent patients with neuromuscular and respiratory control disorders, aged 6 weeks to 12 years, admitted to a tertiary paediatric intensive care unit between 2009 and 2011.

RESULTS

Edi monitoring identified markedly abnormal respiratory dynamic patterns that were not always apparent clinically. These were associated with disorders of central respiratory control, muscle weakness and diaphragm pathology.

CONCLUSIONS

Edi monitoring using NAVA technology is a valuable, minimally invasive, diagnostic adjunct in children with neuromuscular and respiratory control disorders who are ventilator-dependent.

Extubation process in bed-ridden elderly intensive care patients receiving inspiratory muscle training: a randomized clinical trial

Background

The purpose of this study was to evaluate the extubation process in bed-ridden elderly intensive care patients receiving inspiratory muscle training (IMT) and identify predictors of successful weaning.

Methods

Twenty-eight elderly intubated patients in an intensive care unit were randomly assigned to an experimental group (n = 14) that received conventional physiotherapy plus IMT with a Threshold IMT^® device or to a control group (n = 14) that received only conventional physiotherapy. The experimental protocol for muscle training consisted of an initial load of 30% maximum inspiratory pressure, which was increased by 10% daily. The training was administered for 5 minutes, twice daily, 7 days a week, with supplemental oxygen from the beginning of weaning until extubation. Successful extubation was defined by the ventilation time measurement with noninvasive positive pressure. A vacuum manometer was used for measurement of maximum inspiratory pressure, and the patients’ Tobin index values were measured using a ventilometer.

Results

The maximum inspiratory pressure increased significantly (by 7 cm H₂O, 95% confidence interval [CI] 4–10), and the Tobin index decreased significantly (by 16 breaths/ min/L, 95% CI −26 to 6) in the experimental group compared with the control group. The Chi-squared distribution did not indicate a significant difference in weaning success between the groups (χ² = 1.47; P = 0.20). However, a comparison of noninvasive positive pressure time dependence indicated a significantly lower value for the experimental group (P = 0.0001; 95% CI 13.08–18.06). The receiver-operating characteristic curve showed an area beneath the curve of 0.877 ± 0.06 for the Tobin index and 0.845 ± 0.07 for maximum inspiratory pressure.

Conclusion

The IMT intervention significantly increased maximum inspiratory pressure and significantly reduced the Tobin index; both measures are considered to be good extubation indices. IMT was associated with a reduction in noninvasive positive pressure time in the experimental group.

Noninvasive work of breathing improves prediction of post-extubation outcome

PURPOSE

We hypothesized that non-invasively determined work of breathing per minute (WOB(N)/min) (esophageal balloon not required) may be useful for predicting extubation outcome, i.e., appropriate work of breathing values may be associated with extubation success, while inappropriately increased values may be associated with failure.

METHODS

Adult candidates for extubation were divided into a training set (n = 38) to determine threshold values of indices for assessing extubation and a prospective validation set (n = 59) to determine the predictive power of the threshold values for patients successfully extubated and those who failed extubation. All were evaluated for extubation during a spontaneous breathing trial (5 cmH(2)O pressure support ventilation, 5 cmH(2)O positive end expiratory pressure) using routine clinical practice standards. WOB(N)/min data were blinded to attending physicians. Area under the receiver operating characteristic curves (AUC), sensitivity, specificity, and positive and negative predictive values of all extubation indices were determined.

RESULTS

AUC for WOB(N)/min was 0.96 and significantly greater (p < 0.05) than AUC for breathing frequency at 0.81, tidal volume at 0.61, breathing frequency-to-tidal volume ratio at 0.73, and other traditionally used indices. WOB(N)/min had a specificity of 0.83, the highest sensitivity at 0.96, positive predictive value at 0.84, and negative predictive value at 0.96 compared to all indices. For 95% of those successfully extubated, WOB(N)/min was ≤10 J/min.

CONCLUSIONS

WOB(N)/min had the greatest overall predictive accuracy for extubation compared to traditional indices. WOB(N)/min warrants consideration for use in a complementary manner with spontaneous breathing pattern data for predicting extubation outcome.

Phlebotomy for rapid weaning and extubation in COPD patient with secondary polycythemia and respiratory failure

The increased incidence of ventilator-associated complications in patients with chronic obstructive pulmonary disease (COPD) necessitates rapid weaning and extubation. The presence of secondary polycythemia in this subgroup increases the incidence of stroke and myocardial infarction due to hyperviscosity and tissue hypoxia. We present a 58-year-old male patient of COPD with secondary polycythemia (hematocrit 64%) who had possible hyperviscosity-related complications leading to cardiac arrest after a minor surgical procedure. The patient developed ventilator dependence after recovery. Phlebotomy was done to remove 10% of total blood volume. Symptomatic improvement was dramatic. Improvement in weaning indices like rapid shallow breathing index and PaO₂/PAO₂ was observed facilitating rapid weaning and early extubation. Monitored, acute phlebotomy is safe and cost-effective. It decreases blood volume and viscosity, increases cardiac output and improves exercise tolerance in patients.

Serum trace element levels in COPD patient: the relation between trace element supplementation and period of mechanical ventilation in a randomized controlled trial

BACKGROUND AND OBJECTIVE

Many trace elements play important roles in activating or inhibiting enzymatic reactions, by competing with other elements and metalloproteins for binding sites, by affecting the permeability of cell membranes and by other mechanisms. They play important roles in the oxidant/antioxidant balance. As such, trace elements are thought to be involved directly or indirectly in the pathogenesis of several diseases. The aim of the present study is to investigate the effect trace elements (Se, Mn and Zn) intravenously administered on the period the COPD patients spend on mechanical ventilation.

METHODS

In a randomized double-blinded controlled trial a set of 120 subjects (40 normal volunteers and 80 COPD) were recruited. Serum concentration levels of Se, Mn and Zn were determined for all enrolled subjects with Inductively Coupled Plasma spectroscopy. COPD patients received intravenous supplementation of the above trace elements and the period the patients spent on mechanical ventilation was determined.

RESULTS

There was a significant reduction (P = 0.013) in the period the patients with COPD spent on the mechanical ventilation when received intravenous supplementation (9.4 +/- 7.3 days) compared with the COPD patients who received placebo (17.8 +/- 7.6 days).

CONCLUSIONS

Trace element (Se, Mn and Zn) status is altered in critically ill patients with COPD. The supplementation achieved a reduction in the period those patients spent on the mechanical ventilation. A larger multi-centre trial is required to confirm this preventive effect and to explore its applicability to other critical care conditions.

Fade of Pulmonary Function During Residual Neuromuscular Blockade

OBJECTIVES

A decrement in evoked muscle force with repetitive nerve stimulation (fade) suggests impaired neuromuscular transmission. We tested the hypothesis that fade of pulmonary function, ie, a decrease in values of FVC with the second spirometric maneuver compared to the first maneuver, occurs during impaired neuromuscular transmission.

DESIGN

Prospective study.

PARTICIPANTS

Six healthy male volunteers.

INTERVENTIONS

A series of three consecutive spirometric maneuvers was performed every 5 min in six awake healthy volunteers before, during, and after partial paralysis evoked by rocuronium (0.01 mg/kg IV plus 2 to 8 microg/kg/min).

MEASUREMENTS AND RESULTS

We measured FVC, FEV(1), forced inspiratory volume in 1 s (FIV(1)), peak expiratory flow (PEF), and peak inspiratory flow (PIF) by spirometry, and force of adductor pollicis muscle by mechanomyography (train-of-four [TOF] stimulation). A statistically significant fade (reduction of the second maneuver from the first maneuver) of FVC, FEV(1), FIV(1), PEF, and PIF was observed during neuromuscular blockade. With peak relaxation (TOF ratio, 0.5) fade amounted to medians of 10% (interquartile range [IQR], 9 to 23%), 7% (IQR, 2 to 16%), 31 (IQR, 19 to 47%), 9% (IQR, 3 to 24%), and 30% (IQR, 5 to 43%), respectively. A fade of >or= 10% was always associated with a clinically relevant (>or= 10%) FVC reduction from baseline (ie, FVC before rocuronium administration). However, FVC reduction from baseline was still present in 23% of measurements without a relevant FVC fade.

CONCLUSIONS

A clinically relevant fall (fade) in FVC from the first to the second value during or after neuromuscular blockade suggests impaired pulmonary function and may be due to muscle paralysis. For this reason, the first (best) FVC value may overestimate pulmonary function and expose the patient to an unidentified risk.

Mechanical Ventilation

Mechanical ventilation is the second most frequently performed therapeutic intervention after treatment for cardiac arrhythmias in intensive care units today. Countless lives have been saved with its use despite being associated with a greater than 30% in-hospital mortality rate. As life expectancies increase and people with chronic illnesses survive longer, artificial support with mechanical ventilation is also expected to rise. In one survey, over half of senior internal medicine residents reported their training on mechanical ventilation as inadequate, whereas the majority of critical care nurses reported having received no formal education on its use. Technological advances resulting in the availability of sleeker ventilators with graphic waveform displays and new modes of ventilation have challenged the bedside clinicians to incorporate this new data along with evidenced-based research into their daily practice. A review of current thoughts on mechanical ventilation and weaning is presented.

Biofeedback as a supportive method in weaning long-term ventilated critically ill patients

Weaning a patient from mechanical ventilation is occasionally a difficult process complicated by the patient's emotional state. Anxiety, agitation, depression and other emotional disturbances can start a vicious circle between fear of losing breath and dyspnea that impairs the process of withdrawing ventilatory support. A biocybernetic loop model is suggested that integrates psychological variables (e.g., capacity of self-control, self-confidence, sense of self-efficacy) as important factors for a successful weaning. The paradigm of biofeedback is regarded as a suited approach to strengthen these psychological factors. It means the externalization of physiological functions especially of those from the autonomous nervous system so that a patient becomes aware of them. In the case of the ventilated patient, it is assumed that the transformation of the respiratory activities into perceptible (acoustic and visual) signals supports the patient's self-controlling behaviour during the weaning process. He gets positive reinforcement for his efforts to influence his breathing intentionally and, by continuous and immediate information, he regains self-confidence to control his somatic functions effectively. The application of biofeedback is mainly described in single case studies. They all report a decrease in the respiratory rate and an increase in the tidal volume. The need for a controlled study is suggested that would answer the question of whether biofeedback is an appropriate psychological tool to facilitate the weaning process in mechanically ventilated patients.

The pulmonary physician in critical care. 11: critical care management of respiratory failure resulting from COPD

Survival to hospital discharge of patients suffering exacerbations of COPD is better than other medical causes for ICU admission. Although non-invasive ventilation (NIV) may prevent progression to tracheal intubation, its failure in most cases should lead to a period of controlled mechanical ventilation aiming for early extubation, possibly supported by NIV and tracheostomy if this fails. A greater understanding of the physiological principles behind ventilatory support of patients with COPD should reduce patient-ventilator disharmony and avoid the excessive use of sedation. The risk of nosocomial infection increases with the length of time the patient remains in the ICU and commonly further prolongs the period of ventilator dependency. Weaning centres with an emphasis on general rehabilitation may offer the best support for such individuals.