None listed
Conditions
Brief summary
Intensive care clinicians use Mechanical Ventilation on a daily basis in the ICU to treat patients with injured lungs. An important setting on the ventilator machines is known as positive end expiratory pressure or PEEP. This controls the pressure in the lung at the end of the breath, and its accuracy is critical in the successful treatment of injured lungs. Currently, doctors have no standard way of selecting the PEEP for each patient, and use their clinical intuition, or their “gut-feeling”. Different patients have different lungs and as such, selecting PEEP this way might lead to an incorrect PEEP setting for that patient. This might cause the patient to require longer stays in the ICU and/or or further lung injury. This study aims to evaluate a computer based method of PEEP selection and is based on prior research conducted here in the Christchurch ICU. Because this method of PEEP selection is specific to each patient, it is anticipated ventilation better matched to their lungs. This could lead to healthier lungs and as a result, require the patient to spend less time in the ICU.
Interventions
The planned interventions will test the response of patient lung when it is ventilated at different positive end expiratory pressure (PEEP) to determine the best PEEP settings specific to each patient at a particular time.
The best PEEP is found to occur during minimal elastance. Minimal elastance PEEP is able to maximise lung recruitment and avoid overdistension. It is important ventilation is optimised as soon as possible when the patient is admitted to the ICU. Delayed proxy consent will be
The planned interventions will test the response of patient lung when it is ventilated at different positive end expiratory pressure (PEEP) to determine the best PEEP settings specific to each patient at a particular time. The best PEEP is found to occur during minimal elastance. Minimal elastance PEEP is able to maximise lung recruitment and avoid overdistension. It is important ventilation is optimised as soon as possible when the patient is admitted to the ICU. Delayed proxy consent will be sought for these reasons. The intervention tests a mathematical model (Time-varying elastance model) to better inform intensive care clinicians about the lung condition, and select a PEEP at minimal elastance during a PEEP titration protocol. Patients whose PEEP selected by the mathematical model, implemented by the clinician, will be compared with the outcomes of patients who have had their PEEP determined solely by clinical judgement. Details of PEEP titration protocol 1. A staircase recruitment manoeuvre (RM) is performed (C.L. Hodgson et al., 2011). During RM, PEEP is increased in steps of 5cmH2O from a base level of 5cmH2O PEEP. 2. PEEP is increased until peak airway pressure (PIP) reaches a limit of 55cmH2O (or lower, if clinician feels this is too high for the patient) 3. Each PEEP is maintained for 10-15 breathing cycles before a subsequent increase. 4. Elastance is calculated at each PEEP 5. The minimum elastance PEEP is determined 6. This PEEP is recommended to the attending clinician 7. If the clinician feels this PEEP is appropriate, they will re-perform steps 1 and 2. The purpose of this increase is to re-recruit the lung after decremented portion of RM. On the decremented portion of the RM, the clinician will end the PEEP decrease on the recommended PEEP. 8. Otherwise the clinician will set the PEEP to a PEEP they feel is more appropriate. If the clinician chooses to ignore the model suggestion, this will be recorded. Further the data from the patient will still be recorded. Every 3 hours or when the patient is turned in the bed the following adjustments are to be made: 1. PEEP is increased in 3 steps of 2cmH2O with 10~15 breathing cycles at each step. 2. If the Elastance shows an increase at each and every step, then revert back to the original PEEP setting minus 1cmH2O. 3. If the Elastance shows a decrease at each and every step, then set to the final PEEP setting (a total of 6cmH2O increase in PEEP). 4. If the Elastance decreases at the first step and then increases at any subsequent step, then set to the PEEP that yielded the minimum Elastance value during the adjustment procedure. 5. If the Elastance increases at the first step and then decreases at any subsequent step, then leave PEEP at original setting. This instance is cause for the clinician to consider a full recruitment manoeuvre. The study will run for at least 48 hours, and until there has been significant resolution of their lung condition. Following each intervention, clinical staff in the ICU will be given the option of following the recommended settings as determined by the mathematical model. Data regarding clinician compliance with the protocol, the number of low oxygen recordings (using standard pulse oximetry monitoring), length of mechanical ventilation and ICU stay, total oxygen “dose” and ICU mortality will be collected and compared with a matched cohort.
Sponsors
Canterbury District Health Board
Study design
Allocation
Non-randomised trial
Primary purpose
Treatment
Eligibility
Sex/Gender
All
Age
16 Years to No maximum
Healthy volunteers
No
Inclusion criteria
1. Patient on mechanical ventilation. 2. Patients diagnosed with all degrees of ARDS (PF ratio <300) as per the Berlin Definition (2012) (The ARDS Definition Task Force, A. 2012), by intensive care clinicians. 3. Arterial line in situ.
Exclusion criteria
1. Patients who are likely to be discontinued from MV within 24 hours. 2. Patients aged less than 16. 4. Patients who are moribund and/or not expected to survive for more than 72 hours. 5. Patients whose care could be compromised if given increased sedation and/or muscle relaxants for the purpose of assessing lung recruitment. 6. Lack of clinical equipoise by ICU medical staff managing the patient.
Outcome results
None listed