Oesophageal Doppler ultrasound in the assessment of haemodynamic status of patients admitted to the medical intensive care unit with septic shock.

Introduction: Haemodynamic monitoring is an essential element in the management of critically ill patients in the intensive care unit (ICU). However, there have been increasing concerns about the clinical utility and safety profile of the invasive pulmonary artery catheter (PAC). Oesophageal Doppler (ED) monitoring has emerged recently as a safer and less invasive tool which can be used by the intensivist to estimate cardiac output in the critically ill patient. Validation studies have thus far only been performed in surgical patients perioperatively and in mixed surgical/medical ICU patients. Currently, minimal data are available in any sizeable Asian population or in patients with severe sepsis. The assumption that these normograms and data hold true for our local medical ICU patients may not be valid due to differences in body habitus.

Materials And Methods: Our primary aim is to validate the oesophageal Doppler as a reliable measure of cardiac index, systemic vascular resistance (SVR) and preload in our local Asian population of patients with severe sepsis and septic shock in the medical ICU. This was a prospective pilot study on 12 consecutive mechanically ventilated patients in our medical ICU with the diagnosis of septic shock as defined by SCCM/ESICM/ACCP/ATS/SIS International Sepsis definitions Conference-Critical Care Medicine 2003 and required PAC haemodynamic monitoring as indicated by Medical Intensive Care Unit attending.

Results: Ninety-seven paired cardiac output measurements were made. Cardiac output ranged from 2.87 to 11.0 L/ min (calculated cardiac index ranging from 1.73 to 6.36 L/min/m2) when measured using the PAC with thermodilution technique and from 2.0 to 12.1 L/min (calculated cardiac index of 1.2 to 7.2 L/min/m2) using the trans-oesophageal Doppler. There was moderately good correlation between CIpac and CIed (correlation coefficient, r = 0.762 with PCA = 58%). The mean bias was 0.26 L/min/m2 (P <0.07), while the limit of agreement was +/- 1.44 L/min/m2.

Conclusion: ED has good correlation with PAC in measuring cardiac index in Asians with septic shock but is an unreliable measure of both pre-load and SVR.