A colleague, Dr Paddy Dobbs (@S6LFC) recently attended an Advanced Ventilation Symposium organised by Drager.
In order to allow those who were unable to attend the meeting to gain a flavour of the topics covered by the speakers he has created a summary of the key points of each talk.
The title of each talk is shown along with the details of the speaker.
Mechanical ventilation beyond the conventional, Luigi Camporota (London)
- First intervention should be prone.
- After prone 6 mls/ kg TV and limit plateau pressure to 28-30cm H2O.
- Then optimise PEEP, various methods mentioned including PEEP trials & thoracic impedence.
Lung protective Strategies, Marco Ranieri (Italy).
- HFOV increases mortality. Interesting comment about the difference in the two trials, an English trial didn’t protocol the conventional arm whereas the Canadian trail did and showed a greater difference in mortality.
- [Video of last year’s talk on HFOV available here]
- It is important to understand that pressures within small airways can be greatly amplified in heterogeneous lung, this can lead to massive shear forces. Seen in deformation of the lung with consolidation/collapse
- Sometimes the 6mls/kg and limit of plateau pressure to 28-30cmH2O will be insufficient to protect lungs- can have tidal hyperinflation.
- Consideration of trans pulmonary pressure is vitally important in lung protective strategies.
- Ptp = Palv – Pip. Where Ptp is transpulmonary pressure, Palv is alveolar pressure, and Pip is intrapleural pressure.
- Can be much larger for NIV than IPPV
ECMO Past present and Future, Giles Peek (Leicester)
- ECMO is great, except for respiratory needs in Japan where its rubbish, however they’re really good at it for cardiac needs.
- Also quite good if you have bird flu & actually don’t need ECMO, when survival is 85%.
- Future is more cardiac ECMO (? Longer term CPB)
ECCO2R (Extracorporal CO2 Removal), Marco Ranieri (Italy)
- May protect patients who develop ventilator related lung injury despite protective strategies.
- There is not enough information as to whether the risks of bleeding outweigh the benefits of ECCO2R compared with NIV or IPPV (pointed out that ECMO has a similar lack of evidence) BUT unable to do a RCT as now difficult to get ethics/ trial approval.
Ventilation in the obese patient, Mike Margarson (Chichester)
BMI not as helpful as looking at the patient. 3 types:
- •Pear shape- not bad despite very high weights, usually easy to intubate & ventilate
- “Good” Apple fat around centre, but loose & extra-abdominal. Abdo looks flat on lying supine
- “Bad” Apple fat central and intra-abdominal, Abdo looks round on lying flat. BEWARE
Fat has several problems, metabolic activity:
- endocrine function leading to a pro-thrombotic and pro-inflammatory state
- fat related diseases such as diabetes, IHD etc etc.
- fat cell mass: OSA, Atelectasis, airway narrowing & collapse
Patients with very, very high BMI’s (>70) tend to be pear shaped and have less incidence of difficult airways than those with BMI<70. This is mainly because “Apple” die when BMI’s get to >55-60.
Ventilation issues: ↑ o2 consumption,CO2 production, CO, Alveolar ventilation
Need greater PEEP than expected (up to 15cmH2O G Tusman Anesth Analg2014)
Note although MRI’s can take upto 200kg in weight, practically BMI>45 limits access to the bore.
Spontaneous breathing during mechanical ventilation, Nader Habashi (USA)
Video lecture available here.
- Feedback of breathing to the brainstem is very complex.
- If a patient is ventilated and there is sternal recession during the respiratory cycle then the patient should be sedated deeper or paralysed. May need PEEP optimised before breathing again. ARDSnet suggest increased flow.
- Look for dips in pressure trace before and after mandatory breaths- may also need to increase flow.
- These dips suggest air hunger & can lead to fatigue.
- Spontaneous breaths with the diaphragm contracting, leads to diaphragmatic contraction, squeezing the liver, reduced RA pressure and increased venous return- i.e. a Good thing & to be encouraged- keep the diaphragm working!
Weaning and the BREATHE Trial, Luigi Camporota (London)
- 20% fail weaning
- 40% of time in critical care is weaning
- Failed intubation 11x increase in mortality ( can lead to ventriclular dilatation & failure)
- Weaning divided into simple, difficult & prolonged.
Suggest framework for weaning:
• Screen phase
• Predictive tests
• Confirmatory test
• Extubation (or liberation from ventilation for the physician based intensivists)
Pi max trail after 20s (Pi increases with time, need several breaths)
T-piece trial (or “flow by” setting on vent) best as predictive trial, because work of breathing similar to extubated compared with PEEP or ASB
BREATHE trial- under recruited (“possibly as its been devised by a physician” Anon in the audience)
Is there a role for regional long term ventilation and weaning centres, Andrew Bentley (Manchester)