Monitoring of pacemaker induced changes in cardiac output with inspired to endtidal oxygen difference in paediatric cardiac surgery patients.
METHODS
Fourteen children aged 4-15 months were studied after corrective cardiac surgery. Heart rate was increased by 20% with an external pacemaker. Cardiac output (CO) was measured with thermodilution. Oxygen saturation was measured in systemic artery (SaO2), central vein (ScvcO2) and pulmonary artery (SvO2). Inspiratory to endtidal oxygen difference (FI-ETO2) was measured using a paramagnetic technique. SvO2 was measured continuously using a spectrophotometric technique.


RESULTS
CO increased in three patients and decreased in 11 patients during pacing. Regression between DeltaCO and Delta(1/Sa-vO2), Delta(FI-ETO2/Sa-vO2), Delta(FI-ETO2/Sa-cvcO2) showed r=0.70, r=0.76 and r=0.75, respectively. DeltaCO exceeded 10% in 17 of 26 interventions. Changes in FI-ETO2 of equal direction as changes in CO occurred in 12 of these 17 interventions.


CONCLUSIONS
Estimations of CO changes, based on SvO2, can be enhanced if changes in FI-ETO2 are also measured. ScvcO2 instead of SvO2 gives equivalent results. Sudden changes in FI-ETO2 after pacemaker initiation or termination can predict the direction of CO changes.
Department of Paediatric Anaesthesia and Intensive Care, The Queen Silvia Children's Hospital, Göteborg University, S-416 85 Göteborg, Sweden.
J
J
Bengtsson
K E
KE
Edberg
B
B
Nilsson
J P
JP
Bengtson
D002245:Carbon Dioxide / Q000502:physiology; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial; D006348:Cardiac Surgical Procedures; D005260:Female; D006330:Heart Defects, Congenital / Q000601:surgery; D006801:Humans; D007223:Infant; D008297:Male; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000097:blood / Q000502:physiology*; D010101:Oxygen Consumption; D011182:Postoperative Care; D012119:Respiration; D013815:Thermodilution
D002245:Carbon Dioxide; D010100:Oxygen