Yasuhiko Watanabe

Blood Volume measurement at the bedside using ICG pulse spectrophotometry.

Background In the treatment of critically ill patients, blood volume (BV) measurement requires injection of some tracer substance and subsequent blood sampling to analyze the tracer concentration. To obviate both the sampling and laboratory analysis, techniques of pulse oximetry have been adapted to the noninvasive optical measurement in the patients nose or finger of the arterial concentration of an injectable dye. Methods The authors report the clinical accuracy of a new noninvasive bedside BV measurement test that uses pulse spectrophotometry (the pulse method). The device detects pulsatile changes of tissue optical density of a nostril or a finger spanned by a probe emitting two infrared wavelengths (805 and 890 nm). After a peripheral or central intravenous injection of indocyanine green, the arterial dye concentration is continuously computed by reference to the previously measured blood hemoglobin concentration. Three types of tests of its accuracy are described here. Results In 10 healthy volunteers, the authors compared BV determined by the pulse method with an131 I‐labeled human serum albumin method. Three subject data sets were excluded because of motion artifact, a low signal:noise ratio, or both. For the other seven volunteers, the bias +/− SD of pulse spectrophotometric BV values were 0.20 +/− 0.24 1 (or 4.2 +/− 4.9%) for the nose probe and 0.34 +/− 0.31 1 (or 7.3 +/− 6.9%) for the finger probe, with a mean BV of 5 l. In 30 patients who underwent cardiac surgery, the pulse method was compared with a standard indocyanine green method using intermittent blood sampling. In three patients, the BV could not be determined by the pulse method because of motion artifact, low signal:noise ratio, or both. In 27 patients, the bias +/− SD of the BV by the pulse method was ‐0.23 +/− 0.37 l (‐5.3 +/− 8.7%) for the nose and ‐0.25 +/− 0.5 l (‐4.2 +/− 8.4%) for the finger. Patient BV ranged from 2.51 to 7.13 l (mean, 4.48 l). In 10 additional patients before cardiac surgery, BV was measured by the pulse method before and shortly after removal of 400 ml blood. The pulse method recorded a decrease of BV of 480 +/− 114 ml. Three days after venesection, the mean BV was 117 +/− 159 ml less than the predonation control. Conclusions In most patients, the pulse method provides bedside measurement of BV without blood sampling (except for hemoglobin determination), with an estimated error less than 10%. In 10‐30% of tests the method failed because of motion distortion of the record during the 10‐min data collection period or because of insufficient pulse amplitude in the test tissue.

Assessment by pulse dye-densitometry indocyanine green (ICG) clearance test of hepatic function of patients before cardiac surgery : its value as a predictor of serious postoperative liver dysfunction

OBJECTIVE Patients with preoperative liver dysfunction occasionally have a poor prognosis after cardiac surgery because the liver condition is aggravated. The pulse dye-densitometry indocyanine green (ICG) clearance test was used as a preoperative evaluation technique. DESIGN Prospective, clinical evaluation. SETTING Surgical intensive care unit of a national cardiovascular center. SUBJECTS Twenty-seven patients with preoperative liver dysfunction were studied. They were divided into four groups depending on the cause of their liver dysfunction. INTERVENTIONS With the patients informed consent, a bolus of ICG, 20 mg, was injected, and the disappearance of ICG was measured noninvasively by pulse dye-densitometry. MEASUREMENTS AND MAIN RESULTS The ICG retention rate at 15 minutes (ICG-R15) was calculated for the regression time. The patients were assessed in terms of ICG-R15 and the cause of liver dysfunction. The ICG-R15 values obtained for all 27 patients were 30% +/- 16% (mean +/- standard deviation). The 21 survivors had ICG-R15 values of 24% +/- 12%, whereas the 6 patients who died after surgery had significantly greater ICG-R15 values of 50% +/- 13% (p < 0.05). The mean values of ICG-R15 in patients with congestive liver, viral hepatitis accompanied by congestive liver, viral hepatitis, and cirrhosis were 34%, 23%, 13%, and 42%, respectively. The 6 of 27 patients who died after surgery had ICG-R15 values greater than 40%. Five of the seven patients with cirrhosis died. CONCLUSION These results suggest that (1) compared with Child-Pugh classification, the value of ICG-R15 provides a more accurate surgical indication; and (2) liver dysfunction from cirrhosis causes postoperative deterioration of liver function, especially when the ICG-R15 value exceeds 40%.

Value of Mild Hypothermia in Patients Who Have Severe Circulatory Insufficiency Even After Intra-Aortic Balloon Pump

STUDY OBJECTIVE To evaluate the effectiveness of mild hypothermia in postcardiac surgical patients with severe heart failure in spite of conventional medical therapy and the use of intra-aortic balloon pumping (IABP). DESIGN Prospective, clinical study. SETTING Teaching hospital. PATIENTS 10 postcardiac surgical patients with severe heart failure despite the use of IABP with massive doses of catecholamine. INTERVENTIONS Patients underwent mild hypothermia produced by surface cooling (to approximately 34.5 degrees C). Hemodynamic criteria for the induction of hypothermia included a cardiac index (CI) of less than 2.2 L/min/m2 with a pulmonary capillary wedge pressure (PCWP) of up to 18 mmHg despite the use of IABP with massive doses of catecholamine. MEASUREMENTS AND MAIN RESULTS After control measurements had been taken at normal core body temperature (37 degrees C), patients were cooled to approximately 34.5 degrees C (using a cooling blanket and gastric lavage with cold water) to decrease tissue oxygen (O2) demand. Patients showed significant improvements in CI (1.9 +/- 0.3 to 2.2 +/- 0.3 L/min/m2), mixed venous O2 saturation, (SvO2; 55 +/- 7 to 64 +/- 6%), and urine output (2.1 +/- 1.1 to 3.4 +/- 2.2 ml/kg/hr). Patients were rewarmed while SvO2 was being monitored. The duration of the hypothermia was 38 +/- 41 hours. Oxygen delivery increased in 8 of the 10 patients, the mean value (+/- SD) for the group rising from 309 +/- 65 ml/min/m2 to 358 +/- 57 ml/min/m2 as temperature was reduced from 36.7 +/- 0.4 degrees C to 34.7 +/- 0.3 degrees C. All patients were successfully weaned from IABP at 140 +/- 107 hours after admission to the intensive care unit. CONCLUSIONS Mild hypothermia is a simple and useful procedure for improving the circulation of postcardiac surgical patients with severe heart failure despite the use of IABP.

Antiphospholipid Antibody Syndrome in a Case with Redo Coronary Artery Bypass Grafting Under Cardiopulmonary Bypass

A patient who underwent redo coronary artery bypass grafting developed severe thrombocytopenia. A platelet transfusion caused recurrent hypotension and hypoxia. The patient status was complicated by a systemic thrombosis including coronary graft occlusion and central vein thrombosis. We found that the lupus anticoagulant, as well as other autoimmune antibodies, was positive only after the thrombotic episode developed. Even though the lupus anticoagulant returned to negative about 2 months after the episode of graft occlusion, the patient eventually died of heart failure.

Helium/oxygen breathing improved hypoxemia after cardiac surgery: case reports.

14 breaths/min under volume-controlled ventilation without muscle relaxants, which was sufficient to maintain normocapnea) and Pao, did not improve. After admission to the intensive care unit (ICU), her arterial blood oxygenation failed to improve despite vigorous therapy, including nebulization of a bronchodilator, an 1:E ratio of 0.75, and PEEP of up to 10 cm H,O. Use of high PEEP (15-20 cm H,O) was avoided in order to prevent hemodynamic deterioration. (Her cardiac index [CI] and central venous pressure were 2.0-2.3 L * min-’ * m-’ and 9-13 mm Hg, respectively, with support by intravenous dopamine and dobutamine at a rate of 5 Fg * kg-’ . min-’ each.) Bronchial secretion was not pathologic, and her chest radiograph showed no significant change (Fig. 1). On the second postoperative day, when Pao, had decreased to 56 mm Hg with a FIO, of 1.0 and the intrapulmonary shunt fraction (Qs/Qt) was calculated to be 35%, He/O, was initiated. Helium (purity, 99.9%) was connected to the compressed-air port of a Servo-ventilator 900-C. The required FIO, decreased and the fraction of helium thus increased: Pao, was 50 mm Hg with a FIO, of 40.5 and Qs/Qt of 31% some 15 min after the initiation of He/O, (Fig. 2). Pace, was slightly decreased (42 + 37 mm Hg). Peak inspiratory pressure (PIP, 24 + 24 cm H,O), CI (2.4 + 2.5 L * min-’ * m-‘), and a systolic systemic blood pressure (127 + 129 mm Hg) showed no change. After 2 h of inhaling He/O,, oxygenation remained good and reached the normal range after 12 h.