| Background Septic shock is the common disease in Intensive Care Unit, the mortality as high as 40%. And the microcirculation dysfunction is the main physiopathology manifestation. Dobutamine--the first choice inotrope for the septic shock patients, could increase cardiac ouput and the oxygen delivery. However, there was difference on the effect of dobuamine acts on the microcirculation. We has identified the dobutamine stress test could predicted the septic shock patients prognostic. So we assumed that compared with nonresponder to the stress test, those microcirculation whose responders to the stress test could improve.Objective The objective of this study is to evaluate the relationship between the responder to dobutamine stress test and the microcirculation in septic shock patients.Method Patients were included when they met criteria for septic shock, fluid resuscitation to the state that passive leg raising could not increase cardiac output by 10 percent. Data were recorded from each patient included demographic (eg, sex, age), major diagonosis, infection sites, and Acute Physiology and Chronic Health Evaluation (APACHE) Ⅱ scores and Sequential Organ Faielure Assessment (SOFA) scores from the first 24 hours on the ICU. Swan-Gans catheter was inserted through internal jugular vein.Cardiac output was measred by thermodilution method. Central venous pressure, mean pulmonary arterial pressure, pulmonary arterial wedge pressure were monitored using calibrated pressure transducer. Mean systamic arterial pressure was contimously monitored via an indwelling radial artery catheter.Artrial samples and mixed venous samples were performed on a gas nanlyzer.Oxygen delivery and oxygen consumption were calculated.The sublingual microcirculation was recoded with the side dark field microscope. A dobutamine stress test was performed —dobutamine (5-10ug/kg/min) continuous infusion for 1 hour, the hemodynamic, oxygen metabolism and the sublingual microcirculation were recoded again. Any patient who was able to increase oxygen consumption by>15% was designated a responder to the test.And any patient who was able to increase his or her oxygen consumption by<15% was designated a nonresponder to the test. As a safeguard, in case of cardiovascular instability, such as tachycardia> 150 bpm, life threatening hypotension, acute ST changes in the cardiac monitor, the physician stopped the study.Result 26 patients were enrolled. All patients were 71.30 ± 12.85 years old.The dosage of the norepinephrine was 16.65 ± 14.87 ug/min.As they enrolled, the hemoglobin was 10.11 ± 1.54 g/dl.(1)Dobutamine significantly increased heart rate(89.11 ± 19.06 vs.107.31 ± 24.03 bpm,p＜0.05), cardiac output index (3.37 ± 1.21 vs.4.17 ± 1.44 L/min.m2,p<0.05) and oxygen delivery (441.12 ± 138.56 vs.544.66 ± 198.43 ml/min.m2,p<0.05). There was no difference in total vascular density(19.12 ± 2.82 vs.18.82 ± 2.67 vessels/mm), perfused vascular density(15.64 ± 2.51 vs.15.37 ± 2.72 vessels/mm), proportion of perfused vascular(79.72 ± 6.40 vs.80.36 ± 6.88%), microvascular flow index (2.58 ± 0.22 vs.2.68 ± 0.24)and heterogeneity index(0.27 ± 0.11 vs.0.24 ± 0.10).(2) Of all patients,12 patients were responders, the other 14 patients were nonresponders. There was no difference in age(74.57 ± 8.73 vs.70.00 ± 13.53 years), basal APACHEII score(26.17 ± 6.16 vs.23.00 ± 6.93), SOFA score(9.50 ± 3.96 vs. 9.64 ± 2.73) and the dosage of norepinephrine(18.58 ± 14.08 vs.15.00 ± 15.85 ug/min) both the groups. Compared with the responders,there was no difference in total vascular density(-0.34 ± 2.68 vs.-0.56 ± 1.87 vessels/mm), perfused vascular density(0.08 ± 2.03 vs.-0.67 ± 2.12 vessels/mm), proportion of perfused vascular(3.62 ± 5.33 vs.-1.49 ± 7.01%), microvascular flow index(0.17 ± 0.23 vs. 0.03 ±0.17) and heterogeneity index(-0.03 ± 0.05 vs.-0.03 ± 0.14). Also with their change value.(3)But for those cardiac output index increasing by 10 percent, compared to the baseline, the microvascular flow index improved(2.55 ± 0.20 vs.2.64 ± 0.25,p＜0.05), however, there was no difference in the total vascular density(-19.07 ± 2.59 vs.18.36 ± 2.41 vessels/mm), perfused vascular density(15.56 ± 2.32 vs.14.92 ± 2.55 vessels/mm), proportion of perfused vascular(79.56 ± 5.99 vs.79.86 ± 7.84%), and heterogeneity index(0.28 ±0.10 vs.0.25 ± 0.08). Of all patients, there was 19patients whose caridac output index increased by 10%.Dobutamine increase the oxygen delivery(556.54 ± 182.86 vs.422.07 ± 109.45 ml/min.m2, p<0.001)and oxugen consuption(114.79 ± 24.13 vs.98.92 ± 19.64 ml/min.m2, p=0.013),and dobutamine improved the MFI(2.55 ±0.20 vs.2.64 ± 0.25,p=0.042). Of the 19 patinets,9 patients was the responder to the stress test. For the responder,compared to the baseline,dobutamine increased heart rate(91.56 ± 15.67 vs.112.22 ± 12.94 bpm, p=0.001),cardiac output index(3.12 ± 0.73 vs.4.36 ± 1.34 L/min.m2, p=0.001), oxygen delivery(429.08 ± 124.91 vs.593.35 ± 247.74 ml/min.m2,p=0.007) and oxugen consuption(91.76 ± 21.67 vs.128.67 ± 29.83 ml/min.m2, p<0.001).But dobutamine failed to improve the microcirculation. Meantimes, for the nonresponder, compared to the baseline,dobutamine increased heart rate(81.00 ± 19.50 vs.97.60 ± 21.68 bpm,p＜0.001), cardiac output index(3.13 ± 1.55 vs.3.99 ± 1.81 L/min.m2, p=0.002), oxygen delivery(415.76 ± 174.88 vs.523.41 ± 204.38 ml/min.m2,p=0.002). But dobutamien failed to improve oxygen consumption and the microcirculation.Conclusion Patients whose the responders to dobutamine stress test had no relevance to the microcirculation change. |
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