Monitoring cardiac output during hyperbaric oxygen treatment of haemodynamically unstable patients.

Introduction: Patients suffering from necrotizing fasciitis (NF) are often haemodynamically unstable and require extended monitoring of cardiovascular parameters; yet this is limited during hyperbaric oxygen treatment (HBOT). We aimed to evaluate the use and safety of transoesophageal Doppler (TED) monitoring of cardiac output (CO) under hyperbaric conditions in haemodynamically unstable patients diagnosed with NF and sepsis or septic shock.

Methods: Cardiac output was measured prior to, during and after HBOT with the use of TED in seven consecutive patients diagnosed with NF and sepsis or septic shock. The HBOT followed our standard protocol for NF patients, consisting of 90 minutes' exposure to 100% oxygen at 284 kPa. The difference between mean CO just prior to HBOT initiation and at near-maximum treatment duration was assessed using the Student's paired t-test.

Results: TED was feasible and easy to use under hyperbaric conditions. We experienced no problems with the measurement of CO or with equipment-related safety during HBOT. Five patients had an increase in CO from initiation of HBOT to near-maximum treatment duration, one patient had a stable CO, while one patient experienced a slight decrease in CO. Overall, there was an increase in mean CO of 1.7 L min-1 (95% CI 0.02 to 3.34 L min-1, P = 0.048) from initiation of HBOT to near-maximum treatment duration.

Conclusion: This is, to the best of our knowledge, the first study to document that TED can provide a minimally-invasive estimate of CO in haemodynamically unstable patients with NF and sepsis or septic shock during HBOT.