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Early continuous noninvasive haemodynamic monitoring after severe blunt trauma
G C Velmahos1, C C Wo, D Demetriades
1Department of Surgery, University of Southern California School of Medicine, Los Angeles, USA. velmahos@hsc.usc.edu
Background:
Invasive haemodynamic parameters obtained by pulmonary artery (PA) catheterization from survivors' patterns were reported to provide criteria for therapeutic goals in high-risk elective surgery and accidental injuries. This approach is limited because PA catheterization requires critical care conditions; however, noninvasive methods can provide early information anywhere in the hospital.
Objectives:
To evaluate the feasibility of using noninvasive haemodynamic monitoring of patients with severe blunt trauma immediately after emergency department (ED) admission and to describe the early time course of haemodynamic events in survivors and nonsurvivors of blunt trauma.
Setting:
A large, academic, level-I trauma centre.
Design:
Prospective, descriptive haemodynamic study.
Patients And Methods:
38 severely injured patients, 22 (58%) survivors and 16 (42%) nonsurvivors, with ISS > 15 were monitored by: (a) an improved thoracic bioelectric impedance device that estimated cardiac output noninvasively and continuously, (b) simultaneous arterial oxygen saturation by pulse oximetry, (c) noninvasive blood pressure measurement and (d) transcutaneous oxygen and carbon dioxide sensors. The patients were monitored as soon as possible upon arrival at the ED and continued during the first 24 h or more after admission. When the patient reached the ICU, monitoring by PA catheterization was undertaken to validate the noninvasive methods and for continued diagnostic evaluations.
Results:
Cardiac output estimations by thermodilution and bioimpedance were well correlated; r = 0.91. Survivors started with high cardiac index (CI) values that subsequently rose to over 4 L/min/m2; arterial oxygen saturation (SaO2), transcutaneous oxygen tension and transcutaneous-oxygen-tension-to-inspired-fraction-of-oxygen-concentr ati on (PtcO2/FiO2) values were normal in survivors and higher than those of the nonsurvivors. In the 1st h after admission, nonsurvivors' blood pressures were higher than normal and higher than that of the survivors, but in the 2nd and 3rd h, both groups were in the normal range; thereafter, nonsurvivors' values were lower than survivors' and often lower than normal.
Conclusions:
The noninvasive haemodynamic monitoring system provides reasonably accurate, continuous, on-line, real-time display of haemodynamic data that show marked differences in the early patterns of survivors and nonsurvivors. The study suggests noninvasive monitoring may be used for early detection and correction of posttraumatic circulatory deficits.