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A-43 Intra-aortic balloon pump dynamics at altitude
A-43
A-44
INTRA-AORTIC BALLOON PUMP DYNAMICS AT ALTITUDE.
MYOCARDIAL OXYGENDEMAND IN CARDIAC PATIENTS DURIN6 HELICOPTERTRANSPORT
David Bowers, Jo Estes; Life Flight Duke Univ. Med. Cir./ Box 3520 Durham, NC 27710
William F. Rutherford, E11zabeth Crooks, Charles J. Fisher, Jr. University AlrCare, University Hospltals of Cleveland, 2074 Ablngton Rd., Cleveland, OH 44106.
INTRODUCTION: Intra-aortic balloon counterpulsation is an effective treatment for the failing heart. The use of the intraaortic balloon pump (IABP) is a temporizing measure until definitive interventions can be initiated. This option is available in a growing number of institutions, many of which may not have resources for definitive care/ necessitating transfer to a tertiary care facility. The technology is now available to transport patients dependent on an IABP via helicopter. The lack of documented research in the area of IABP dynamics at altitude has created the need for further investigation. METHODS: A clinically approved Datascope 90T IABP and Datascope PerCor Star DL IABP catheters were used while operating the system in a hypobaric chamber, simulating ascents to 12,000 feet and descending to sea level. Boyle's ideal gas law was used as a conceptual framework to compare predicted changes in gas volume and pressures to in-vitro measurements. Transducers recorded changes in the pressure of the drive gas while volume displacement recordings were made of the balloon during the ascents and descents. A linear regression model was used to analyze pressure and volume changes to altitude, with significance set at p ~5. RESULTS: Emperical calculations using Boyle's gas law indicate that as ~ t i ~ d e increases volume within the balloon w i ~ decrease resulting in incomplete inflation and less than optimal augmentation. CONCLUSION: To prevent over/under~ll of the pneumatic drive of the IABP caused by volume/pressure changes of the drive gas/ the IABP should be "purged" every 2000 feet of ascent or descent.
40
SEPTEMBER/OCTOBER AM$
~LIMfJA~ Anglna and Infarct.lonoccur when myocardlal oxygen oemano exceeos supply. Both heart rate (HR) and rate-pressure product (RPP) are strongly correlated wlth myocardial oxygen consumption (MV02). RPP = (systolic BP) X (HR). Thls study was Inltlatedto determine If HR, SBP, RPP, and estimated MV02 !ncrease. slgnlflcantly durlng hellcopter transport oT cardlac patients. Methods: 89 consecutlve patients wlth prlmary cardlovascular diagnoses were revlewed. Pre-fllght and maxlmum In-fllght mean values for HR, SBP, RPP, and MV02 were evaluated, for significant differences using 5tuoent's t-test Data was analyzed by dlagnostlc groups: acute myocardial infarctlon (less t6an 24 hours, labeled AMI), anqlna (ANG), other (OTH), and for all patlenl~s(ALL). Results: (Displayed as mean % change from pre-fllght values + S.E.M.)n = number of patients per group. n HR SBP RPP AMI(49) 5.0+_1.5* 10.3+_1.6W I 1.2+2.0W ANG (9) 5.0+_2.5 6.4+2.5~'~ 10.7+4.I~~ OTH(31) 5.6+2.0W 12.2+3.4W 15.9+5.4W ALL(89) 5.2+I.IW 10.6+1.5W 12.8+2.2~ = p < 0,01 ~-~ = p < 0.05 Mean estimated MV02 in ALL increased by 20% + 4% (p < 0.001), wlth a range of-61~ to 196%. Conclusion: Cardiac patients undergoing transport b.y helicopter exhlblt.slgnlHcant increases in HR, SBP, RPP, ano estimated MV02, which can potentially preclpltate or Increase the slze of Infarction. Appropriate control groups must be evaluated to determine if the increased alues are due solely to helicopter ransport, and if the Increased MV02 Ist clinically significant. Close attention' should be paid to controlling pain, anxlety, and adrenerglc tone through analgesia, sedation, and perhaps short-acting f~-blockade.
~
A-44
INTRA-AORTIC BALLOON PUMP DYNAMICS AT ALTITUDE.
MYOCARDIAL OXYGENDEMAND IN CARDIAC PATIENTS DURIN6 HELICOPTERTRANSPORT
David Bowers, Jo Estes; Life Flight Duke Univ. Med. Cir./ Box 3520 Durham, NC 27710
William F. Rutherford, E11zabeth Crooks, Charles J. Fisher, Jr. University AlrCare, University Hospltals of Cleveland, 2074 Ablngton Rd., Cleveland, OH 44106.
INTRODUCTION: Intra-aortic balloon counterpulsation is an effective treatment for the failing heart. The use of the intraaortic balloon pump (IABP) is a temporizing measure until definitive interventions can be initiated. This option is available in a growing number of institutions, many of which may not have resources for definitive care/ necessitating transfer to a tertiary care facility. The technology is now available to transport patients dependent on an IABP via helicopter. The lack of documented research in the area of IABP dynamics at altitude has created the need for further investigation. METHODS: A clinically approved Datascope 90T IABP and Datascope PerCor Star DL IABP catheters were used while operating the system in a hypobaric chamber, simulating ascents to 12,000 feet and descending to sea level. Boyle's ideal gas law was used as a conceptual framework to compare predicted changes in gas volume and pressures to in-vitro measurements. Transducers recorded changes in the pressure of the drive gas while volume displacement recordings were made of the balloon during the ascents and descents. A linear regression model was used to analyze pressure and volume changes to altitude, with significance set at p ~5. RESULTS: Emperical calculations using Boyle's gas law indicate that as ~ t i ~ d e increases volume within the balloon w i ~ decrease resulting in incomplete inflation and less than optimal augmentation. CONCLUSION: To prevent over/under~ll of the pneumatic drive of the IABP caused by volume/pressure changes of the drive gas/ the IABP should be "purged" every 2000 feet of ascent or descent.
40
SEPTEMBER/OCTOBER AM$
~LIMfJA~ Anglna and Infarct.lonoccur when myocardlal oxygen oemano exceeos supply. Both heart rate (HR) and rate-pressure product (RPP) are strongly correlated wlth myocardial oxygen consumption (MV02). RPP = (systolic BP) X (HR). Thls study was Inltlatedto determine If HR, SBP, RPP, and estimated MV02 !ncrease. slgnlflcantly durlng hellcopter transport oT cardlac patients. Methods: 89 consecutlve patients wlth prlmary cardlovascular diagnoses were revlewed. Pre-fllght and maxlmum In-fllght mean values for HR, SBP, RPP, and MV02 were evaluated, for significant differences using 5tuoent's t-test Data was analyzed by dlagnostlc groups: acute myocardial infarctlon (less t6an 24 hours, labeled AMI), anqlna (ANG), other (OTH), and for all patlenl~s(ALL). Results: (Displayed as mean % change from pre-fllght values + S.E.M.)n = number of patients per group. n HR SBP RPP AMI(49) 5.0+_1.5* 10.3+_1.6W I 1.2+2.0W ANG (9) 5.0+_2.5 6.4+2.5~'~ 10.7+4.I~~ OTH(31) 5.6+2.0W 12.2+3.4W 15.9+5.4W ALL(89) 5.2+I.IW 10.6+1.5W 12.8+2.2~ = p < 0,01 ~-~ = p < 0.05 Mean estimated MV02 in ALL increased by 20% + 4% (p < 0.001), wlth a range of-61~ to 196%. Conclusion: Cardiac patients undergoing transport b.y helicopter exhlblt.slgnlHcant increases in HR, SBP, RPP, ano estimated MV02, which can potentially preclpltate or Increase the slze of Infarction. Appropriate control groups must be evaluated to determine if the increased alues are due solely to helicopter ransport, and if the Increased MV02 Ist clinically significant. Close attention' should be paid to controlling pain, anxlety, and adrenerglc tone through analgesia, sedation, and perhaps short-acting f~-blockade.
~