non- conventional forms of respiratory support...bleeding ( cyclocapron / novo 7) hit ( rx with...
TRANSCRIPT
Non- conventional forms of
respiratory support
Dr Liesel Bosenberg
Specialist Physician & Fellow in Critical Care Medicine
Kalafong & Steve Biko Academic Hospitals
Points we will ponder:
ECMO
Liquid Ventilation
High frequency ventilation
One lung ventilation
Heliox
ECMO: Extra Corporeal Membrane
Oxygenation
In 1885 Franz and Gruber developed a device to oxygenate blood extracorporeal
In 1937 the first heart-lung machine was invented by Gibbon
In 1956 Clowes developed a membrane oxygenator “artificial lung”
ECMO introduced in 1972
Two main modalities:
Veno-Arterial ECMO: mainly for
Haemodynamic Support but can offer
respiratory support
Veno-Venous ECMO: only respiratory
support
ECMO: Indications:
VA ECMO:
Post- cardiotomy ( unable to liberate patient off bypass machine )
Post-heart transplant : primary graft failure
Severe CCF: decompensated cardiomiopathy, ACS with cardiogenic shock, sepsis,miocarditis,drug overdose
Bridge to transplant or VAD
Respiratory support
VV ECMO:
Hypoxemic respiratory failure with PF ratio < 100 mmHg despite optimal ventilatory settings and support ( ARDS due to whatever cause)
Hypercapnoeic respiratory failure with pH < 7.2 ( exacerbation of COPD)
Primary graft failure following lung transplantation
Relative contra-indications:
Conditions where anticoagulation is contra-indicated
Mechanical ventilation> 7 days ( ECMO considered an early intervention to make any difference)
If VAD/ transplant is contra-indicated
Pre-existing liver, renal failure, severe AI, aortic dissection
Advanced age, morbid obesity, neurodysfunction ( SBI), pre-existing poor functional status
Disseminated malignancy, Graft vs Host disease
Unwitnessed cardiac arrest/ arrest of unknown duration
ECMO: Technique:
Vascular access, tubing, oxygenator
Blood oxygenated , CO2 removed ,
reinfused into native system
Initiation: anticoagulate patient with IV
heparin then insert cannulae
Cannulation : position of catheter tips
in VV ECMO important
Titration:
Clearly defined respiratory and HD goals
Targets: ScvO2/ SvO2 75 %- 80%
VA ECMO: SaO2 100%
VV ECMO: SaO2 85-100%
Adequate tissue perfusion as determined by BP, Blood lactate and other determinants pertaining to DO2
Maintenance:
Maintain flow rates once foals are achieved
AC: continuous heparin infusion aPTT 210-230 s
Platelets > 100
Pplat < 30 cm H2O
FiO2 < 0,5
Aim for weaning off vasopressors in cases of VV ECMO
Early tracheostomy
Light sedation
Special considerations:
1. Blood Flow Rates:
Different for VA vs. VV ECMO
Higher in VV ECMO
FR in VA should be enough to still provide adequate preload to maintain LV output otherwise consider inotropes, IABP
2. Diuresis:
Ultrafiltration can be added only once stable on VV ECMO
3. LV monitoring:
VA ECMO in patients with underlying/ pre-existing LV dysfunction
Increased afterload due to retrograde flow
Insufficient unloading of LV
ECMO unloads RV – leads to decrease in preload
If uncontrolled- leads to progressive LV distension, left atrial Hypertension and intra-pulmonary haemorrhage
Consider inotropic support with dopamine, milrinone or even IABP
4. Mechanical issues:
ECMO flow can be very volume dependant
Will drop with hypovolemia, malpositioning of cannulae, pericardial effusion and pneumothorax
Management includes a fluid challenge, exclusion of tamponade, pneumothorax and abdominal distension/ compartement syndrome
Discontinuation:
Improved CXR
Improved SaO2
Improved pulmonary complience
In case of cardiac patients, increase in BP
requiring vasodilators, return of pulsatility of
the arterial pressure wave form
TOE is useful to establish the degree of
cardiac recovery
Complications:
Bleeding ( Cyclocapron / Novo 7)
HIT ( Rx with argatroban)
Thromboembolism
Cannulation –related :Limb ischaemia, vessel perforation, arterial dissection
Haemolysis
GIT perforation, ulceration due to changes in splanchnic perfusion
VA ECMO: pulmonary haemorrhage, pulmonary infarction, arterial thrombosis, coronary and cerebral hypoxia
Evidence: Cesar Trial Conventional ventilation versus ECMO for Severe Adult Respiratory failure
Peek GJ et al. Lancet 2009 Oct 17;374(9698):1351-63.
The first randomized trial data supporting the use of ECMO in the adult population were published in 2009 by Peak and colleagues.
The Conventional Ventilation or ECMO for Severe Adult Respiratory Failure (CESAR) trial, through a minimization strategy, enrolled 180 patients with severe ARDS (Murray score > 3 or pH < 7.20).
They were randomized to either care at a tertiary care center or transfer and management at a single ECMO center.
Of the 90 patients randomized for transfer to the ECMO center, 5 died prior to or during transfer, and 16 improved with conventional management. Sixty-eight patients received ECMO support, and overall survival or severe disability at 6 months was 63% for the ECMO group vs 47% for the conventional management group.
Appropriate criticisms of this study have focused on the lack of standardized management in the controls. Also, statistical significance was lost if patients from the ECMO center cohort who did not receive ECMO were removed. Many have reflected on CESAR as a trial of transfer of patients with severe ARDS to a comprehensive center with ECMO support rather than a trial of the ECMO technology itself.
Extra- Corporeal CO2 removal
( ECCO2R):
VV removal of CO2 at lower flow rates than ECMO; high diffusion gradient
Percutaneous catheterisation – simplifies vascular access
Heparinised membrane lung – no systemic anticoagulation needed
Usually combined with LFPPV ( 2-3 breaths a minute)
AV shunt, driven by BP of patient, no pump necessary
Novalung: iLA membrane
ventilator : PECLA ( pumpless extracorporeal
lung assist ; TAU Medical
Liquid ventilation:
Technique of mechanical ventilation where the lung are insufflated with PFC liquid – acts as an inert carrier of O2 and CO2
Advantages:
Decreases surface tension by maintaining fluid interface in alveoli
Decreases risk of barotrauma- hydraulic pressure opens alveoli
High efficiency heat exchanger
PFC’s:
Ideal fluid: non-toxic and chemically stable
Lower surface tension
Minimal systemic absoprtion
Able to dissolve large amounts of O2 and CO2
Thus: PFC fits all the above criteria
Also: does not wash out surfactant
Stored indefinately at room temperature
Dissolves 15x more oxygen than plasma
High viscosity
Liquid Ventilation:
Total LV: entire lung filled with liquid, tidal volume pumped into and out of lung
Partial LV: lungs slowly filled with volume of PFC close to FRC during gas ventilation
Physiological outcomes:
Alveolar recruitment
Better V/Q matching
Lavage ( removal of exudative material from lung )
Temperature regulation
Anti-inflammatory effects
LV:
Adult applications:
ARDS
Pneumonia( lavage, antibiotics e.g. gentamycin can be suspended in PFC vehicle)
Drug delivery
Cancer treatment ( augment the effects of radio- and chemotherapy)
Donor lung preservation
Adverse effects:
PFC fluid is 2x more dense than saline
( interfere with accurate weighing of
patient)
Radio-opaque : limited utility of CXR
Interfere with normal breath sounds
Requires deep sedation and paralysis
High Frequency ventilation: HFJV, HFOV, HFPV
HFOV:
Rescue treatment for severe oxygenation failure
Eligibility: patients with ARDS/ ALI , > 35 kg, currently failing on CV with a lung protective strategy
FiO2 > 60%, PEEP > 10 with a P/F ratio< 200
Plateau pressure > 39 cm H2O
Presence of bilateral infiltrates on CXR consistent with ARDS
Oxygenation index >24
OI: FiO2 x Pmean x 100 / PaO2
Decreases VILI and barotrauma
Provides a tidal volume below that of the anatomical dead space at Hz of > 60 breaths /min
( RR:3-15 Hz ; 900 breaths/min)
Potential benefits include:
Less HD compromise
Improved V/q matching
Indications in adult patients:
ALI/ ARDS
Severe UAO with Stridor
Bronchopleural fistula ( HFJV)
Contraindications:
COPD
Complications:
Inspissation and desiccation of
mucous
Airway damage at very high speed
Air trapping with generation of auto
PEEP
Dynamic hyperinflation
Evidence:
MOAT 2 trial ( multicentre oscillatory
ventilation for ARDS trial):
Derdak S, Mehta et al. High Frequency oscillatory ventilation for
ARDS in Adults: A randomized control trial. Am J Respiratory Critical
Care Medicine 2002; 166:801-808
Safety and efficacy of HFOV
148 ARDS
patients, randomized to HFOV/ CV
HFOV group: increased mean airway pressure, significant
improvement of PF ration within the first 16 hours , limited to no
benefit past 24 hours
30 day mortality rate 37 % in HFOV group vs. 57 % in the CV group
MOAT 2 :
Unfortunately study was not powered adequately to show a clinical significant decrease in mortality
Other evidence:
Mehta et al performed a retrospective review of 156 cases in which HFOV was performed as rescue treatment
Patients received on average 5.6-7.6 days of CV prior to HFOV
PF ratio and OI improved for > 72 hrs
One lung ventilation:
OLV in critical care:
Only 3 main indications for OLV
To improve surgical access
Lung protection
Unilateral lung disease in critically ill
patient: single lung transplant
Heliox:
Helium is a low density , inert gas with very solubility in blood
When nitrogen is substituted with helium in the gas mixture, the airway resistance in the absence of anatomical change
Used in patients with increased Paw; it improves ventilation and decreases work of breathing
Clinical studies several limitations:
< 30 patients enrolled
Inclusion and exclusion criteria not standardized making comparison difficult
Heliox interferes with the performance of diagnostic equipment
Indications for use:
Children:
UAO due to compression, post extubation stridor and croup
LAO : ARDS, Status asthmaticus, bronchiolitis
Bronchopulmonary dyplasia
Adults:
UAO: thyroid mass, radiation injury,angioedema, cancer
LAO: severe asthma and COPD
Asthma:
Used in cases of severe respiratory failure with associated respiratory acidosis
2 small uncontrolled series of patients
60-80% He
Improvement of respiratory indices with decrease of CO2 by 35 mmHg
COPD:
Acute exacerbation of COPD
In combination with NPPV
Decrease in PaO2 , dyspnoea, work of
breathing, improvement of respiratory
pattern
Current recommended
indications:
Mechanical UAO
Postoperative stridor
Severe COPD and NPPV
Severe asthma with respiratory failure
refractory to standard therapy
Bibliography:
The End