title: A novel approach to assess hemorrhagic shock severity using the arterially determined left ventricular isovolumic contraction period.
abstract: Recently, the ventilatory variation in pre-ejection period (ΔPEP) was found to be useful in the prediction of fluid-responsiveness of patients in shock. In the present study we investigated the behavior of the ventilation-induced variations in the systolic timing intervals in response to a graded hemorrhage protocol. The timing intervals studied included the ventilatory variation in ventricular electromechanical delay (ΔEMD), isovolumic contraction period (determined from the arterial pressure waveform, ΔAIC), pulse travel time (ΔPTT), and ΔPEP. ΔAIC and ΔPEP were evaluated in the aorta and carotid artery (annotated by subscripts Ao and CA) and were compared with the responses of pulse pressure variation (ΔPPAo) and stroke volume variation (ΔSV). The graded hemorrhage protocol, followed by resuscitation using norepinephrine and autologous blood transfusion, was performed in eight anesthetized Yorkshire X Landrace swine. ΔAICAo, ΔAICCA, ΔPEPAo, ΔPEPCA, ΔPPAo, ΔPPCA, and ΔSV showed significant increases during the graded hemorrhage and significant decreases during the subsequent resuscitation. ΔAICAo, ΔAICCA, ΔPEPAo, and ΔPEPCA all correlated well with ΔPPAo and ΔSV (all r ≥ 0.8, all P < 0.001). ΔEMD and ΔPTT did not significantly change throughout the protocol. In contrast with ΔPEPAo, which was significantly higher than ΔPEPCA (P < 0.01), ΔAICAo was not different from ΔAICCA. In conclusion, ventilation-induced preload variation principally affects the arterially determined isovolumic contraction period (AIC). Moreover, ΔAIC can be determined solely from the arterial pressure waveform, whereas ΔPEP also requires ECG measurement. Importantly, ΔAIC determined from either the carotid or aortic pressure waveform are interchangeable, suggesting that, in contrast with ΔPEP, ΔAIC may be site independent.
authors.affiliation: Experimental Cardiology, Thoraxcenter, Cardiovascular Research Institute, Cardiovascular Research School Erasmus University Rotterdam, Erasmus University Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands;
authors.forename: Marc J
authors.initials: MJ
authors.lastname: van Houwelingen
authors.forename: Daphne
authors.initials: D
authors.lastname: Merkus
authors.forename: Jan
authors.initials: J
authors.lastname: Hofland
authors.forename: Jan
authors.initials: J
authors.lastname: Bakker
authors.forename: Robert
authors.initials: R
authors.lastname: Tenbrinck
authors.forename: Maaike
authors.initials: M
authors.lastname: Te Lintel Hekkert
authors.forename: Geert
authors.initials: G
authors.lastname: van Dijk
authors.forename: Arnold P G
authors.initials: AP
authors.lastname: Hoeks
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Duncker
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D009200:Myocardial Contraction / Q000502:physiology*; D012151:Resuscitation; D012720:Severity of Illness Index; D012771:Shock, Hemorrhagic / Q000175:diagnosis* / Q000503:physiopathology; D013318:Stroke Volume / Q000502:physiology*; D013552:Swine
keywords: graded hemorrhagic shock; heart-lung interactions; resuscitation; systolic timing intervals; ventilatory variation