Automated Control of Mechanical Ventilation During General Anaesthesia

Study Overview
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Brief Summary
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Prospective, bicentric observational study to assess a novel system for automated control of mechanical ventilation (Smart Vent Control, SVC) during general anesthesia.

Detailed Description
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The Automated control of mechanical ventilation during general anesthesia study (AVAS study) is an international investigator-initiated bicentric observational study investigating the application of Smart Vent Control (SVC) during general anesthesia. The main objective of this study is to describe the application of SVC and to assess its safety and efficacy.

Official Title
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Automated Control of Mechanical Ventilation During General Anaesthesia - A Bicentric Prospective Observational Trial

Conditions
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Anesthesia

Intervention / Treatment
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* Device: Smart Vent Control


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Planned elective surgery of the upper limb, lower limb or peripheral vascular surgery in general anesthesia Patient is classified as American Society of Anesthesiologists physical status (ASA) I, II or III Age ≥ 18 years Written consent of the patient for study participation Exclusion Criteria: Mild, moderate or severe acute respiratory distress syndrome (ARDS)[10] Known chronic obstructive pulmonary disease Gold stage III or higher Two or more of the following organ failures Mild, moderate or severe ARDS Hemodynamic instability: systolic blood pressure < 90 mm Hg, mean arterial pressure < 70 mm Hg or administration of any vasoactive drugs. Acute renal failure: oliguria (urine output < 0.5 ml/kg/h for at least 2 hours despite of adequate management or creatinine increase > 0.5 mg/dl Cerebral failure: loose of consciousness or encephalopathy Patient is pregnant.

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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Arms and Interventions

| Intervention/Treatment |
| --- |
|Device: Smart Vent Control|Smart Vent Control (SVC) was designed to automatically control the following ventilator settings: mechanical breathing frequency, inspiratory pressure, pressure support, inspiratory time, trigger sensitivity. SVC adjusts the ventilator settings with the aim to keep a patient stable in a target zone (TZ). Numerous predefined TZs exist that can be set according to the current therapeutic situation. All TZs are adoptable by the user for each individual patient and consist of upper and lower limits for tidal volume and for the partial pressure of end-tidal carbon dioxide (PetCO2). Based on these limits, the system classifies the current quality of ventilation, called Classification of Ventilation, and derives new ventilator settings accordingly. SVC is available as a software option on Zeus Infinity Empowered anesthesia machines (Drägerwerk AG & Co. KGAa, Lübeck, Germany) and is approved as a medical product according to 93/42/European Economic Community.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of adverse events. | Severe hypoventilation defined as minute volume lower than 40 ml/kg predicted body weight for longer than 5 minutes Apnea for longer than 90 seconds Hyperventilation defined as PetCO2 lower than 5 mm Hg of the lower target setting for SVC for longer than 5 minutes Hypoventilation defined as PetCO2 higher than 5 mm Hg of the upper target setting for the SVC for longer than 5 minutes Respiratory rate > 35 breaths per minute for longer than 5 minutes Any override or stop of the automated controlled ventilation settings by the anesthesiologist in charge if the settings are clinically not acceptable. Reasons for overriding or stopping the system will be noted. | During artificial ventilation with SVC (up to 8 hours). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of normoventilated, hypoventilated and hyperventilated patients. | The responsible anesthesiologist defines a target range for the arterial partial pressure of carbon dioxide (PaCO2_target) before the induction of the general anesthesia and sets up the corresponding endtidal CO2-range in the automated ventilation system. 15 minutes after the begin of the surgical procedure an arterial blood gas analysis will be performed and the PaCO2 will be measured. Then patients will be classified as follows: hypoventilated patient: PaCO2 > (PaCO2_target+5) hyperventilated patient: PaCO2 < (PaCO2_target-5) normoventilated patient: (PaCO2_target-5) ≤ PaCO2 ≤ PaCO2_target+5 | During artificial ventilation with SVC (up to 8 hours). | 
| Time period between switch from controlled ventilation to augmented ventilation and achievement of stable assisted ventilation of the patient. |  | During artificial ventilation with SVC (up to 8 hours). | 
| Proportion of time within the target zones for tidal volume and PetCO2 as individually set up for each patient by the user. |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency of alarms. |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency distribution of tidal volume (ml/kg predicted body weight). |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency distribution of inspiratory pressure (mbar). |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency distribution of inspiration time (s). |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency distribution of expiration time (s). |  | During artificial ventilation with SVC (up to 8 hours). | 
| Frequency distribution of PetCO2 (mmHg). |  | During artificial ventilation with SVC (up to 8 hours). | 
| Number of re-intubations. |  | During artificial ventilation with SVC (up to 8 hours). |