Cardiac Output Determination During Experimental Hemorrhage and Resuscitation Using a Transesophageal Doppler Monitor

Effects of postural change on transesophageal echocardiography views and parameters in healthy dogs

The purpose of the present study is to investigate the effect of postural change on transesophageal echocardiography (TEE) views and parameters of interest anesthesia monitoring in healthy dogs. Twelve Beagle dogs were anesthetized and randomly positioned in one of four postures: right lateral-recumbency, left lateral-recumbency, supine position and prone position. After examinations in one posture, the same examination was demonstrated in another posture and repeated in all postures. In each posture, several standard TEE views were demonstrated: longitudinal cranial-esophageal aorta long-axis-view, transverse middle-esophageal mitral valve long-axis-view and transgastric middle short-axis-view. Additionally, echocardiographic parameters were attempted to measure, and direct blood pressure monitoring was performed in each view. As a result, oriented views, except for transgastric middle short-axis-view, could be obtained in all postures. Stroke volume and peak early diastolic velocity of mitral inflow were lower in supine position compared with those in right and left lateral-recumbency. Heart rate (HR) and systemic vascular resistance were higher in supine position compared with those in right and left lateral-recumbency. Left ventricular pre-ejection period/left ventricular ejection time corrected and uncorrected by HR were higher in supine position compared with those in right and left lateral-recumbency. In conclusion, longitudinal cranial-esophageal aorta long-axis-view and transverse middle-esophageal mitral valve long-axis-view provide useful information of interest anesthesia monitoring, because of their views enable to certainly obtain TEE parameters in various postures. Furthermore, TEE parameters allow to detect the changes of preload, afterload and HR that occur in supine position dogs.

Targeted resuscitation strategies after injury

PURPOSE OF REVIEW

The management of the traumatically injured patient has evolved during the past half century despite continually high morbidity and mortality rates. The management of the trauma victim requires timely intervention and damage control in an attempt to maintain normal hemodynamic parameters and adequate systemic perfusion. There is a fine balance between oxygen delivery and consumption, and when this is perturbed, oxygen debt may ensue. The presence of ongoing oxygen debt is rather deleterious, resulting in an inflammatory cascade that can lead to multisystem organ dysfunction. The rapid identification and restoration of oxygen debt are central to the resuscitation of the critically ill patient, be it the result of sepsis or trauma.

RECENT FINDINGS

Resuscitation end points have evolved that allow the physician to more rapidly identify a perturbation between oxygen delivery and consumption. Moreover, end points allow uniformity in gauging the adequacy of resuscitation: preventing under- and overresuscitation and serving as a basis to compare outcome measures in resuscitation trials. Recent technologic advances have allowed a greater wealth of clinical data that can be obtained via less invasive means. Examples of this include esophageal Doppler monitoring, sublingual capnography, orthogonal polarization spectral imaging, and lithium dilution cardiac output determinations. These devices can be used in concert with more traditional resuscitation end points (ie, lactate and base deficit) to maximize oxygen delivery and correct tissue dysoxia. In addition, the management of hemorrhagic shock is continuing to evolve and challenge the dogmatic practices of normotensive resuscitation.

SUMMARY

This review addresses (1) resuscitation end points to optimize cardiac function, (2) resuscitation end points to assess the microcirculation, (3) recent developments in the management of hypotensive hemorrhagic shock, and (4) the translation of early goal-directed therapy from septic shock to use in trauma. Past findings are reflected on and direction for future investigation and clinical practice based on recent clinical advances is provided.