Early experiences with the new awake oesophageal Doppler probe

Editor—We would like to report our early experiences with a new naso-oesophageal Awake Doppler Probe (ADP; Deltex Medical Ltd, Chichester, UK) for monitoring cardiac output. We used it in the setting of critical care outreach assessment and vascular regional anaesthesia.

Oesophageal Doppler is a safe and minimally invasive means of continuously monitoring the circulation.1 It measures blood flow velocity in the descending thoracic aorta from which cardiac output may be reliably calculated. Trends can be followed and response to fluid therapy or vasoactive drugs observed. Previously, patients needed to be heavily sedated to tolerate the larger oro-oesophageal probe, thus limiting its use in awake subjects.

We studied the placement of new nasal ADPs in two groups of awake patients: (i) those referred to the nurse-led outreach team, fulfilling predefined criteria for critical illness, in whom knowledge of their cardiac output was clinically indicated; and (ii) patients undergoing regional anaesthesia for elective endovascular abdominal aortic aneurysm repair.

For each subject we recorded: (i) ease of insertion graded by the operator after topical application of lidocaine 2% gel to the nasopharynx; (ii) time taken to focus the probe; (iii) tolerability of placement, graded using a visual analogue scale (VAS) 0–100, in the surgical group only and before any sedative drugs (this was not recorded in the outreach group as some patients in this group had impaired consciousness); and (iv) any complications associated with insertion.

Fifteen patients studied had a median age of 70 yr (range 36–84 yr). Nine were in the outreach care group and six in the theatre group. Insertion was easy in 12 patients, difficult in one, and impossible in two.

Both failures were in the outreach group. The reasons were: (i) inability to pass the probe through the nostril (one patient); and (ii) inability to tolerate the probe (one patient).

Nine patients could be focused in <3 min, two patients in 3–10 min, and 2 could not be focused. The median VAS for the surgical group was 32.5 (range 10–50). There were no adverse events relating to insertion including epistaxis, despite some patients being coagulopathic or heparinized.

Critical care outreach teams seek to recognize early critical illness and improve patient outcome by timely intervention.2 In our series, 11 of 15 ADPs were easily inserted and quick to focus with no associated morbidity. These early positive experiences for both patient and operator suggest that ADP may offer an extended role for monitoring cardiac output in both awake surgical patients and during perioperative critical care. We wish to thank Deltex Medical Ltd for their provision of the ADPs.

D. Walker, S. Usher, J. Hartin, S. Adam, B. Brandner and S. Chieveley-Williams

London, UK

References

1 Gan TJ, Arrowsmith JE. The oesophageal Doppler monitor: a safe means of monitoring the circulation. Br Med J 1997; 315: 893–4[Free Full Text]

2 Cuthburtson BH. Outreach critical care—cash for no questions? Br J Anaesth 2003; 90: 4–6[ISI][Medline]





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