Intraoperative Neuromuscular Blockade and Postoperative Atelectasis

Study Overview
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Brief Summary
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During one-lung ventilation in thoracic surgery, the intensity of neuromuscular blockade may change the compliance and resistance of ventilated lung, thereby affecting postoperative atelectasis. The present study investigated the effect of the intensity of intraoperative neuromuscular blockade on the postoperative atelectasis using chest computerized tomography in patients receiving thoracic surgery requiring one-lung ventilation.

Detailed Description
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Neuromuscular blocking agents can be used to secure a good surgical field, but it can also cause delayed extubation or postoperative pulmonary complications. Traditionally, rocuronium which is a commonly used non-depolarizing agent is usually reversed by cholinesterase inhibitors such as neostigmine or pyridostigmine. These drugs act by increasing the concentration of acetylcholine at the neuromuscular junction (a competing antagonist), not by direct antagonists. Consequently, there is a risk of pulmonary complications when cholinesterase inhibitor is not used appropriately. Use of sugammadex can reverse neuromuscular blockade (NMB) quickly, thereby being helpful for spontaneous deep breathing postoperatively. In a previous study, the moderate neuromuscular blockade was not guaranteed during surgery because intraoperative train-of-four (TOF) monitoring was not used and the outcome was focused on the correlation between reversal agent and the overall incidence of postoperative pulmonary complications. However, in the present study, TOF ratio or post-tetanic count (PTC) was repeatedly measured during surgery, thereby the intensity of intraoperative NMB being maintained. Moreover, lung compliance was repeatedly measured during surgery and the correlation between the intensity of intraoperative NMB and postoperative atelectasis which is evaluated by quantitative technique was also investigated. Particularly in thoracic surgery, one lung ventilation is usually required for the surgical procedure. During one-lung ventilation, the compliance of ventilated lung is decreased and resistance can be increased, thereby the risk of atelectasis being increased. Furthermore, after thoracic surgery, although patients were encouraged to deep breathe, it is difficult to take a deep breath because of various factors. (i.e. pain, chest tube, long retracted time, postoperative interstitial edema, etc.) Therefore, postoperative atelectasis is much more important in patients undergoing thoracic surgery than other types of surgery. For preventing postoperative atelectasis, the intraoperative intensity of neuromuscular blockade can be a crucial factor. Because deep neuromuscular blockade provides a good lung compliance during mechanical ventilation, peak inspiratory pressure can be decreased, thereby reducing the risk of ventilation-induced lung injury, particularly in one lung ventilation situation.However, there has been still lack of quantitative evidence that deep block is superior to moderate block in the thoracic surgery with one-lung ventilation For assessment of postoperative atelectasis, plain chest radiography may be used. However, plain chest radiography can provide only a qualitative assessment of atelectasis. Computed tomography can assess the whole lung by its density (HU) and enables a quantitative assessment of postoperative atelectasis. Moreover, it can indicate the location of atelectasis more clearly than plain chest radiography, thus provide detailed information about postoperative lung state. To assess the effect of maintaining deep block and sugammadex reversal on the postoperative atelectasis, using chest CT can provide a much more quantitative and valuable information than conventional chest radiography.

Official Title
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The Effect of Intraoperative Neuromuscular Blockade on Postoperative Atelectasis in Patients Undergoing Thoracic Surgery With One Lung Ventilation: Moderate vs. Deep Block

Conditions
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Thoracic Surgery, One-lung Ventilation

Intervention / Treatment
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* Procedure: intraoperative neuromuscular blockade


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients receiving scheduled unilateral lung lobectomy. Patients age ≥19 Patients of American Society of Anesthesiologist Physical Status 1 or 2 Exclusion Criteria: Patients receiving bilateral lung lobectomy Patients BMI > 35.0 or < 18.5 kg/m2 Patients of contraindicated to epidural patients controlled analgesia Patients with neuromuscular disease (i.e. myasthenia gravis) Patients with major burn (more than 3rd degrees) Patients with compromised cardiopulmonary function.

Ages Eligible for Study
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Minimum Age: 19 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Moderate block group<br>maintaining moderate intraoperative neuromuscular blockade (TOF count 1 or 2) during surgery and reversal using sugammadex 2 mg/kg after surgery | Procedure: intraoperative neuromuscular blockade<br>* The intensity of intraoperative neuromuscular blockade<br>|
| Deep block group<br>maintaining deep intraoperative neuromuscular blockade (PTC 1 or 2) during surgery and reversal using sugammadex 4 mg/kg after surgery | Procedure: intraoperative neuromuscular blockade<br>* The intensity of intraoperative neuromuscular blockade<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Atelectasis Area on Chest CT | Atelectasis on Chest CT The lung area was delineated manually. To calculate atelectasis, a region of interest was laid out that encircled the dense part of the lung, excluding large vessels. For further analysis, the lung was divided into four categories: areas with densities ranging from -1000 to -900 Hounsfield units (HU) were classified as over-aerated, from -900 to -500 HU as normally aerated, from -500 to -100 HU as poorly aerated, and from -100 to +100 HU as non-aerated (atelectasis). The proportion of non-aerated lung tissue (-100 to +100 HU) was calculated by dividing the area of the region of interest with the whole lungs. | 1 day after the end of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Patients Defined as Acute Respiratory Distress Syndrome | Acute respiratory distress syndrome can be defined as follows; Bilateral opacities not fully explained by effusions, lobar/lung collapse or nodules on chest radiograph or CT scan and Respiratory failure not fully explained by cardiac failure or fluid overload. Need objective assessment (e.g. echocardiography) to exclude hydrostatic edema if no risk factor present and Partial pressure of pulmonary arterial oxygen / Oxygen friction < 300 mmHg with positive end-expiratory pressure or continuous positive airway pressure of 5 cmH2O. | up to 7 days after the end of surgery | 
| Number of Patients Defined as Pneumonia | Pneumonia can be defined as follows; Two or more serial chest radiographs with at least one of the following (one radiograph is sufficient for patients with no underlying pulmonary or cardiac disease): new or progressive and persistent infiltrates consolidation cavitation; at least one of the following 1) fever (>38.0 C) with no other recognized cause 2) White blood cell count < 4000/ml or >12,000/ml 3) for adults >70 yr, altered mental status with no other recognized cause; and at least two of the following new onset of purulent sputum or change in character of sputum, or increased respiratory secretions, or increased suctioning requirements new onset or worsening cough, or dyspnea, or tachypnea crackles or bronchial breath sounds worsening gas exchange (hypoxaemia, increased oxygen requirement, increased ventilator demand). | up to 7 days after the end of surgery | 
| Number of Patients Showing Pleural Effusion | Pleural effusion can be diagnosed on postoperative radiograph imaging. | 1 day after the end of surgery | 
| Number of Patients Showing Postoperative Desaturation | The number of patients showing desaturation (SpO2 <95%) in room air. | up to 1 day after surgery completed | 
| Number of Patients Requiring Postoperative Re-intubation | The number of patients requiring re-intubation due to postoperative respiratory difficulty. | up to 1 day after surgery completed | 
| Intraoperative Lung Compliance (ml/cmH2O) | Intraoperative lung compliance (ml/cmH2O) can be calculated with peak inspiratory pressure or plateau pressure, positive end-expiratory pressure and tidal volume. | every 1 hour from the time of the tracheal intubation to the end of the skin closure. | 
| Patient Demographic Data | Age in years, Gender, Weight in kilograms, Height in centimeters | on the day of admission | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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one-lung ventilation, thoracic surgery, atelectasis, postoperative pulmonary complication