Inhomogeneous Ventilation in Adult Post-neurosurgical Patients

Study Overview
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Brief Summary
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Inhomogeneous ventilation was more likely to happen in patients after general anesthesia. Inhomogeneous ventilation may associate with ventilator-induced lung injury. A large number of post-neurosurgical patients was delayed extubation and received mechanical ventilation, so that, inhomogeneous ventilation was more likely to happen in the population. Electrical impedance tomography (EIT) is an noninvasive, radiation-free, high temporal resolution, relatively cheap technique in monitoring ventilation distribution bedside. The investigators aimed to investigate the incidence of inhomogeneous ventilation and factors associated with inhomogeneous ventilation in post-neurosurgical patients under mechanical ventilation.

Detailed Description
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Inhomogeneous ventilation was more likely to happen in patients after general anesthesia. Inhomogeneous ventilation may associate with ventilator-induced lung injury since the gravity-depend collapse and over-distention of nondependent regional in patients under mechanical ventilation. A large number of post-neurosurgical patients was delayed extubation and received mechanical ventilation, so that, inhomogeneous ventilation was more likely to happen in the population. Up to now, there is no research reported about the prevalence of inhomogeneous ventilation and the factors associated with inhomogeneous ventilation in post-neurosurgical patients, in present study, The investigators prospectively enrolled adult patients after neurosurgical operations. Electrical impedance tomography (EIT) is an noninvasive, radiation-free, high temporal resolution, relatively cheap technique in monitoring ventilation distribution bedside. The investigators aimed to investigate the incidence of inhomogeneous ventilation and factors associated with inhomogeneous ventilation in post-neurosurgical patients under mechanical ventilation.

Official Title
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Inhomogeneous Ventilation in Adult Post-neurosurgical Patients: an Observational Study

Conditions
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Mechanical Ventilation, Electrical Impedance Tomography, Inhomogeneous Ventilation, Neurosurgery

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Undergoing elective neurosurgery operation Trachea intubated and mechanical ventilated Exclusion Criteria: Age under 18 years-old Unstable hemodynamics patients (mean arterial pressure under 65mmHg) after pharmacotherapy History of chronic obstructive pulmonary disease(COPD) or asthma Contraindication of using EIT (pacemaker, defibrillator, and implantable pumps) Unable to install EIT belt (skin infection, wound) Incompleteness of thorax (e.g. pneumothorax, rib fracture and etc.) or malformation of thorax.

Ages Eligible for Study
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Minimum Age: 18 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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of inhomogeneous ventilation | In supine position, global image of EIT was divided into upper and lower part, each part accounting for 50%, which was named as non-dependent region and dependent region respectively. Inhomogeneous ventilation was defined as the ratio between tidal impedance variation of dependent region(VTdep) and global tidal impedance variation (VT) is less than 45% during stable Spontaneous breath, which was defined as variation of tidal volume less than 10% in continuous 6 breathes. | within 24 hours after neurosurgical operative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of postoperative pulmonary complications(PPCs) | Postoperative pulmonary complication was defined as follows: Pneumonia was defined as recent pulmonary infiltration on chest radiography associated with at least 2 of the following signs: purulent tracheobronchial secretion, a body temperature > 38.3℃，and leukocytes in peripheral blood > 25% above the basal count. Tracheobronchitis was an increase in the volume or a change in the color or purulent aspect of tracheobronchial secretion with a normal chest radiograph. Atelectasis was evidence on chest radiography of pulmonary atelectasis associated with acute respiratory symptoms. Bronchoconstriction was classified as the presence of wheezing associated with acute respiratory symptoms with a good response to inhalatory bronchodilator medication. | 28 days after neurosurgical operative | 
| Length of ICU stay | The number of days that patients stay in ICU. | through study completion, an average of 7 days | 
| Length of hospital stay | The number of days that patients stay in hospital. | through study completion, an average of 28 days |