Discuss ventilator setting for ARDS
As per ARDS Network low tidal volume study trial LTVV management
Mode - SIMV – volume control
Tidal volumes 4-8mls
P-plat <30mmhg
RR is set to achieve minute ventilation requirements
PEEP is titrate with fio2 to achieve oxygenation – (see next question)
Start at intial tidal volume of 6ml/kg pbw
- For females: PBW (kg) = 45.5 + 0.91 * (height [cm] - 152.4)
- For males: PBW (kg) = 50 + 0.91 * (height [cm] - 152.4)
If p-plat is >30 reduce TV by 1ml/kg pbw to a min of 4ml/kg – will often require an adjustment in RR to maintain minute ventilation
permissive hypercapnia – PH >7.2 pco2 <100
List PEEP titration values as per ARDS net
Ventilator setting usual start with fio2 of 1 and PEEP of 5 – this is rapidly reduced to maintain Pao2 and then is titrated to fio2 requirement as below
Fio2 0.3 Peep 5 Fio2 0.4 Peep 5-8 Fio2 0.5 PEEP 8-10 Fio2 .6 Peep 10 Fio2 .7 Peep 10-14 Fio2 .8 Peep 14 Fio2 0.9 Peep 14-18 Fio2 1 Peep 18-24
Discuss ventilator setting for severe pneumonia
Volume controlled
The initial ventilator settings after intubating a patient for refractory hypoxia is typically a tidal volume of
6 to 8 mL/kg ideal body weight, a respiratory rate of 12-16 breaths per minute, an FiO2 of 100%, and a positive end-expiratory pressure (PEEP) between 5 and 10 cm H2O.
Titrate the FiO2 setting down to below 80% once the patient stabilizes while maintaining an arterial saturation above 90%.
Patients who are hypoxic despite high PEEP and FiO2 may benefit from being placed in the prone position.
Discuss ventilator setting for sever asthma/COPD
goals: avoid DHI and hypoventilation
- TV 6mL/kg
- RR 6-10
- short inspiratory time (flow rate 80-100L/min) -> high peak airway pressure but low plateau pressure -> –decreased barotrauma
- Platue pressure should be kept below < 25cmH2O to avoid breath stacking
- I:E of 1:>4
- permissive hypercapnia will result -> sedation and often paralysis initially
- PEEP – traditionally no PEEP was used out of fear of exacerbating Auto PEEP -> but it is now known that PEEP should be set at 60-80% of Auto-PEEP to augment distal airway emptying through splinting airways open
Adjustment of Ventilation
adjust ventilation to degree of DHI (not PaCO2 or pH)
if Pplat > 25cmH2O or cardiovascular suppression -> reduce rate
if Pplat < 25cmH2O -> ventilation can be liberalised with increase in RR and reduction in sedation
hypercapnia is well tolerated but can consider bicarbonate if pH < 7.2
DIscuss physiological changes associated with obesity
Respiratory physiology
- Occur due to physical impingement on lung volumes and chest wall movement, increased metabolic requirement of excess tissue leading to increase WOB and increased o2 consumption and co2 production.
- The above causes
- –Decreased time to desaturation during apnoea
- –increased o2 reqruiements
- –hypoventilation with supine spont ventilation
CVS changes
- increased circulating blood volume
- decreased systemic vascular iresistance
- increased CO by 20-30ml per kg of excess body fat
- LVH
Discuss vent setting in obesity
TV -6-8ml/kg of IBW
RR - adjust to maintain normocapnia (permissive hypercapnia is okay in patients without pulmonary hypertesnion)
-Fio2 to maitnain sats of >92 titrate with Peep likley starting at 10
-recruitment maneuvers if needed
Maintain revers trendelenburg
