Uncalibrated arterial pressure waveform analysis for less-invasive cardiac output determination in obese patients undergoing cardiac surgery.

BACKGROUND: Uncalibrated arterial waveform analysis (FloTrac/Vigileo) uses standard arterial access to determine cardiac output (CO). Calculations are based on arterial waveform characteristics in combination with patient characteristic data to estimate individual arterial compliance. It has been shown that obesity is associated with altered arterial compliance independently of other risk factors. We conducted this study to assess the validity of measuring CO by the FloTrac/Vigileo device in obese patients undergoing cardiac surgery in comparison with bolus thermodilution technique. METHODS: Fifteen obese patients with a BMI of > or = 30 and 23 non-obese patients (BMI 18-25) undergoing coronary artery bypass grafting (CABG) were included. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device (software version 1.10) were obtained intraoperatively after induction of anaesthesia, before cardiopulmonary bypass (CPB), after CPB, and after sternal closure. Measurements in the intensive care unit (ICU) were performed upon arrival in the ICU, after 4, 8, and 24 h after surgery. CO was indexed to the body surface area (cardiac index, CI). RESULTS: The analysis of 262 data pairs revealed a bias and precision of 0.19 and +/-0.66 litre min(-1) m(-2), resulting in a percentage error of 26.6%. Thermodilution CI values ranged from 1.1 to 4.2 litre min(-1) m(-2) [mean 2.4 (0.52) litre min(-1) m(-2)]. Subgroup analysis resulted in a percentage error of 29.8% in obese patients and 24.4% in patients with normal BMI. CONCLUSIONS: The semi-invasive FloTrac/Vigileo device was found to adequately agree with bolus pulmonary artery thermodilution in both obese and non-obese patients undergoing CABG.

Assessment of recovery, dreaming, hemodynamics, and satisfaction in postcardiac surgery patients receiving supplementary propofol sedation with S(+)-ketamine.

BACKGROUND: S(+)-ketamine is an analgesic and sedative drug with dissociative attributes. When it is used without sedatives, nightmares have been described. The aim of this study was to assess the effects of postoperative analgosedation with propofol and S(+)-ketamine when compared to standard propofol analgosedation in terms of recovery, dreaming, hemodynamics, and patient satisfaction. METHODS: Forty-eight patients were sedated with propofol (1-3 mg/kg/h) after coronary artery bypass grafting and allocated randomly on admission to the intensive care unit to receive either S(+)ketamine (2 mg mg/kg/h; group A) or 0.9% saline as a placebo (group B) in a double-blind fashion. If necessary, boli of 3.75 mg piritramide (an opioid) were given in both groups. RESULTS: Patients receiving S(+)-ketamine had significantly higher satisfaction for pain management (Visual Analog Scale [VAS] = group A: median 10 [range 9-10]; group B: median 9 [range 6-10]) despite their lower piritramide consumption. Patients receiving S(+)ketamine showed significantly faster eye opening (82+/-51 vs 156+/-110 min) but dreamed significantly more often (at 2 h, 67% in group A vs 29% in group B; at 24 h, 43% in group A vs 10% in group B), whereas no significant differences were detected in the incidence of nightmares at 2 h, 14% in group A vs 10% in group B; at 24 h, 5% in group A vs 5% in group B. CONCLUSIONS: Patients receiving S(+)-ketamine showed higher satisfaction for pain management and dreamed more often, but they did not have more nightmares.