devices to assist circulation alternative cpr techniques assessment of cpr
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Devices to Assist Circulation
Alternative CPR techniques
Assessment of CPR
Physiology of Ventilation during CPR
Gas distribution will be determined by the relative impedance to flow
Lower esophageal opening pressure and reduced lung-thorax compliance
insp. pressure must be kept low to avoid gastric insufflation
If airway remains patent, chest compression cause substantial air exchange.
Physiology of gas transport during CPR
Decrease CO2 excretion Increase PvCO2
--- buffering acid causes a ↓HCO3-
---↑tissue partial pressure of CO2
Reduce CaCO2 and PaCO2 Low end-tidal CO2 ( ET- CO2 correlate
well with cardiac output during CPR )
ET-CO2 monitoring
High correlation with C.O. ,CPP, initial resuscitation and survival during CPR
Usually to > 20 mmHg during successful CPR
When ROSC , the earliest sign is a sudden increase in ET-CO2 to > 40 mmHg
Higher ET-CO2 associated with an increase in resuscitation
Blood movement during closed chest compression
Cardiac compression pump theoryIntrathoracic pressure pump theory
Blood movement during CPR
Fluctuations in intrathoracic pressure play a significant role in blood flow during CPR
The amount of chest compression is a critical determination of flow , and the quality of chest compression will likely be a major factor in the effectiveness of CPR
Physiology of circulation during standard manual CPR
C.O. severly depressed to 10-30 of ﹪prearrest
Brain blood flow : 20﹪Coronary blood flow : 5-15﹪Lower extremity & abd. visceral flow
< 5 of C.O.﹪
Successful resuscitation
Myocardial blood flow : 15-30 ml/min/loog
Aortic diastolic pressure > 40 mmHgCoronary perfusion pressure
> 20-25 mmHg
CPP higher than 15 mmHg to achieve ROSC
Alternative CPR techniques
Interposed abdominal compression ( IAC ) CPR Active compresion-decompression ( ACD ) CPR Phased thoracic-abd. compression-decompression
( PTACD ) CPR High frequency CPR Vest CPR Simultaneous ventilation-compression ( SVC ) C
PR Invasive CPR
IAC-CPR:Abdominal compression during the rel
axation phase of chest compression“Priming of the intrathoracic pump” be
fore systole“Abdominal pump” mechanism , as IA
BPAbdominal compression point & forceClass II b
IAC-CPR
50 increase in MAP & 37 increase i﹪ ﹪n CPP campared with standard CPR
Survival studies with IAC-CPR haven’t produced consistent results.
ACD-CPR
A suction-cup device to pull up the chest during chest relaxation
“Prime the thoracic pump”Place over mid-sternumA rate of 80-100/min with compression
depth of 1.5~2.0 inches
ACD-CPR
Greater chest expansion
more negative intrathoracic pressure
1. augment venous return
2. increase minute ventilationClass II b
Outcomes of p’t assigned to ACD or standard CPR
ACD
( N=29 )Standard
( N=33)
P-value
Resuscitator 18 ( 62﹪)
10 ( 30﹪)
< 0.003
Survival > 24hr 13 ( 45﹪)
3 ( 9﹪)
< 0.004
Hospital discharge 2 ( 7﹪) 0 NS
From : Cohen T J.N Engl J Med 1993 ; 329 : 1918-21
Outcome according to the resuscitation procedure
ROSC Hospital Discharge
1993 Total 22/56 ( 39.3﹪)
7/56 ( 12.5﹪)
1993 ACD-CPR 10/26 ( 38.5﹪)
3/26 ( 11.5﹪)
1992 STD-CPR 13/43 ( 30.2﹪)
3/43 ( 7.0﹪)
1993 STD-CPR 12/30 ( 40.0﹪)
4/30 ( 13.3﹪)
From : J Cardiothorac Vasc Anesth 1996 ; 10 : 178-186
Factors with improvement in ACD-CPR
Rigorous and repetitive trainingConcurrent use of low-rather than high-dose
Epi.Use of the force gauge Peformance of CPR for a duration sufficient
to prime the pump
PTACD-CPR
Hand-held device that alternates chest compression and abd. decompression with chest decom & abd. compression
Combines the concepts of IAC-CPR & ACD-CPR
Combined 4-phase approach Class : Indeterminate
Vest-CPR“Thoracic pump mechanism” of blood flow Increased inthrathoracic pressure fluctuations ---increased chest compression force ---increased airway collapse during compression Reduced amount of chest deformationGreater transmission of vest pressure to intrathoracic s
paceClass II bUsed in-hospital or during ambulance
High-Frequency CPR( Rapid Compression Rate)
High velocity , moderate force , and brief duration to optimize cardiac stroke volume
A rate of 100-120/min to optimize CBFImprove C.O. & aortic diastolic pressure Class : indeterminate
Mechanical ( Piston) CPR
Optimize effective ext. chest compression and reduce rescuer fatigue
Should be limited to adultDelivery of a consistent rate & depth of
compression Compression-ventilation ratio of 5 : 1
compression duration is 50 of the cycle﹪Class II b
Mechanical ( Piston) CPR
Sternal fracture ExpenseSize , weightRestriction on mobilityDislocation of the plunger
SVC-CPR
Improved peak compression ( systolic ) pressure
Thoracic pump mechanism Pressure gradient between intra & extra-
thoracic vascular beds.Is not currently available for clinical use
Invasive CPR:
Direct cardiac compressionEmergency cardiopulmonary bypass
Direct cardiac compression
Provide near-normal perfusionUsed early (< 25min ) , compression
rate of 60-80/minAssociated with some morbidityShould not be used as a last-ditch effortClass II b
Indication for “open chest” CPR
Penetrating chest trauma with developing cardiac arrest
Cardiac arrest caused by hypothermia , pul. embolism or pericardial tamponade
Chest deformity where closed-chest CPR is ineffective
Penetrating abd. trauma with deterioration & cardiac arrest
Emergency C-P-B
Femoral artery & vein with thoracotomyFor specific , potentially reversible causes
---drug overdoses
---hypothermic arrestClass : Indeterminate
Summary of CPR adjuncts
Specific clinical settingAdditional personnel , training ,
equipmentIncrease forward flow : 20-100﹪Produce little benefit when started late
or late last-ditch measure
Assessment of CPR
Assess hemodynamicsAssess respiratory gasesAssess chest compression
Assessment of Hemodynamics
Pefusion pressurePulse
Assessment of Resp. gases
ABGOximetry : limitated factorsCapnometry
---as an early indicator of ROSC
---Class II b
Assessment of chest compression
Quality of chest compressionResuscitative effort“CPR-plus” during CPR
Class Indeterminate
No good prognostic criteria to assess the efficacy of CPR
Clinical outcome is often the only way to judge CPR efforts
Faster definitive therapy improves surrival better than any variations in CPR technique
Conclusion
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