260 likes | 409 Views
Mechanical Ventilation. Khaled Hadeli, M.D. History. Criteria for mechanical ventilation. Clinical Criteria, i.e. A.B.C Profound respiratory failure RR >35 MIF < 25 cm H2O VC < 10-15 cc/kg PaO2 < 60mm Hg with FIO2 > 60% PaCO2 >50 mm Hg with pH < 7.35. Physiology of MV.
E N D
Mechanical Ventilation Khaled Hadeli, M.D.
Criteria for mechanical ventilation • Clinical Criteria, i.e. A.B.C • Profound respiratory failure • RR >35 • MIF < 25 cm H2O • VC < 10-15 cc/kg • PaO2 < 60mm Hg with FIO2 > 60% • PaCO2 >50 mm Hg with pH < 7.35
Physiology of MV • Air moves in and out of the lung according to pressure gradient • -ve pressure ventilation = creating negative intra thoracic pressure, i.e suck air in. • +ve pressure ventilation = providing high pressure at the mouth, i.e push air in
Types of Ventilators • -ve pressure ventilators • Iron lung • Rocking bed • Ventilator vest
Types of Ventilators cont. • +ve pressure ventilators • Pressure triggered (cycled) • Pressure control (PC) • PC/IRV • Volume triggered (cycled) • Asses control (AC) • SIMV • CMV = PC and AC • PS
AC • CMV, all breaths are machine breaths • Back up rate • Decrease work of breathing • Complications: hyperventilation, Auto peep, ptx, patient need Sedation… • You can start MV with this mode but you can’t wean.
SIMV • Patient can breath- on his own- more than the set rate • May boost with PS • Increased work of breathing • You can start MV and wean with this mode
PC • You set the pressure limit • You set the I:E OR TI • Variable Vm achieved • Need to adequately sedate the patient • Be careful how to put the order, “ total pressure v.s. pressure over the peep”
PC/IRV • Normal I:E ratio = 1:2 • IRV= 1:1, 2:1, 3:1 • Use in ARDS when you can’t adequately oxygenate • By trapping air increases the iPeep and improves oxygenation • Heavy Paralysis and /or heavy sedation
PS • Spontaneous breathing but each breath is boosted • If patient don’t “trigger” the ventilator he will not get the breath • Can be used in combination with SIMV
Ventilatory Settings • Mode: PC, SIMV, AC, etc. • Rate • TV • Peep • Fio2 • PS
Mode of Ventilation • PC ventilation is more physiologic • VC ventilation is used more because it is easy to operate • AC ventilation if you want to rest the patient completely • SIMV is an ok mode if added PS
Rate/ TV • Corrects hypercapnea (respiratory alkalosis) • TV 8-10-12 cc/kg • Correct for height/ gender • Be aware of breath “stacking” • Low TV ventilation/ ARDS
Fio2 • Start with 100% • Use peep to augment • Decrease Fio2 to less than 40% ASAP • 40%-60% low risk for ARDS • More than 60% Dangerous zone
Peep • Physiologic peep about 3 cm • Increase as needed up to 25cm • Peep above 10cm may affect CO • Decrease peep no more than 2.5cm at a time
PS ventilation • Can be an effective mode of ventilation if used solo • Other uses include: combination with SIMV, overcome the ETT resistance, • No PS if pt is on CMV or if pt has no spontaneous breathing • Type of weaning
Special issues • Permissive hypercapnea • Recruitment maneuvers • Best Peep • Lung protective ventilation • Triggering the ventilator • Proning
CPAP • Not a mechanical ventilation • Pt provides the work of breathing • Helps to keep air ways open • Rx sleep apnea (proximal air ways) • Improves oxygenation ( distal air ways) • You can add PS to cpap
NIPPV • CPAP wit /without PS • Bilevel ventilation • Neuromuscular diseases • COPD • Pulmonary edema (CPAP) • High maintenance, needs the cooperation of MD, nurse, RT, and the patient
New modes of ventilations • NO proven efficacy.
Weaning • Should be started ASAP • PS wean • SIMV wean • CPAP/T piece trial • Wean to NIPPV
Liberation from MV • Reversal of the primary condition leading to the respiratory failure • Mental status • Adequate strength “MIF” • F/TV index ( rapid-shallow index) • Spontaneous TV, rate, VC, Compliance
Sedation • Adequate sedation, short acting sedatives with/without pain meds. • Optimize the environment. • Improve sleep cycles. • TERN OF THE TV IN PATIENTS ROOM!! • ICU psychosis
Paralytics • Depolarizing (intubation), CI in denervated patients and with hyperkalemia. • Non-depolarizing. Critical illness paralysis vs. steroid induced narcotizing myositis. • Use minimal doses, avoid steroids, always sedate patients.
Care of the ventilated patient • Nutrition • DVT prophylactics • GI prophylactics • Daily* CXR • Cuff leak • Patient/ventilator synchrony ( sedation, paralysis, triggering, PS…)