Stefan W. Suttner

Colloids versus crystalloids and tissue oxygen tension in patients undergoing major abdominal surgery

UNLABELLED The effects of intravascular volume replacement regimens on tissue oxygen tension (ptiO(2)) are not definitely known. Forty-two consecutive patients scheduled for elective major abdominal surgery were prospectively randomized to receive either 6% hydroxyethyl starch (HES) (mean molecular weight 130 kd, degree of substitution 0.4, n = 21) or lactated Ringers solution (RL, n = 21) for intravascular volume replacement. Fluids were administered perioperatively and continued for 24 h on the intensive care unit to keep central venous pressure between 8 and 12 mm Hg. The ptiO(2) was measured continuously in the left deltoid muscle by using microsensoric implantable partial pressure of oxygen catheters after the induction of anesthesia (baseline, T0), 60 min (T1) and 120 min thereafter (T2), at the end of surgery (T3), and on the morning of the first postoperative day on the intensive care unit (T4). HES 130/0.4 2920 +/- 360 mL and 11,740 +/- 2,630 mL of RL were given to the patients within the study period. Systemic hemodynamics and oxygenation (PaO(2), PaCO(2)) did not differ significantly between the two volume groups throughout the study. From similar baseline values, ptiO(2) increased significantly in the HES-treated patients (a maximum of 59% at T4), whereas it decreased in the RL group (a maximum of -23% at T4, P < 0.05). The largest differences of ptiO(2) were measured on the morning of the first postoperative day. We conclude that intravascular volume replacement with 6% HES 130/0.4 improved tissue oxygenation during and after major surgical procedures compared with a crystalloid-based volume replacement strategy. Improved microperfusion and less endothelial swelling may be responsible for the increase in ptiO(2) in the HES 130/0.4-treated patients. IMPLICATIONS In patients undergoing major abdominal surgery, a colloid-based (with hydroxyethyl starch [HES] 130/0.4) and a crystalloid-based (with lactated Ringers solution [RL]) volume replacement regimen was compared regarding tissue oxygen tension (ptiO(2)) measured continuously by microsensoric implantable catheters. The ptiO(2) increased in the HES-treated (+59%) but decreased in the RL-treated (-23%) patients. Improved microcirculation may be the mechanism for the better ptiO(2) in the HES group.

Goal-directed intraoperative therapy based on autocalibrated arterial pressure waveform analysis reduces hospital stay in high-risk surgical patients: a randomized, controlled trial

IntroductionSeveral studies have shown that goal-directed hemodynamic and fluid optimization may result in improved outcome. However, the methods used were either invasive or had other limitations. The aim of this study was to perform intraoperative goal-directed therapy with a minimally invasive, easy to use device (FloTrac/Vigileo), and to evaluate possible improvements in patient outcome determined by the duration of hospital stay and the incidence of complications compared to a standard management protocol.MethodsIn this randomized, controlled trial 60 high-risk patients scheduled for major abdominal surgery were included. Patients were allocated into either an enhanced hemodynamic monitoring group using a cardiac index based intraoperative optimization protocol (FloTrac/Vigileo device, GDT-group, n = 30) or a standard management group (Control-group, n = 30), based on standard monitoring data.ResultsThe median duration of hospital stay was significantly reduced in the GDT-group with 15 (12 - 17.75) days versus 19 (14 - 23.5) days (P = 0.006) and fewer patients developed complications than in the Control-group [6 patients (20%) versus 15 patients (50%), P = 0.03]. The total number of complications was reduced in the GDT-group (17 versus 49 complications, P = 0.001).ConclusionsIn high-risk patients undergoing major abdominal surgery, implementation of an intraoperative goal-directed hemodynamic optimization protocol using the FloTrac/Vigileo device was associated with a reduced length of hospital stay and a lower incidence of complications compared to a standard management protocol.Trial RegistrationClinical trial registration information: Unique identifier: NCT00549419

The influence of intravascular volume therapy with a new hydroxyethyl starch preparation (6% HES 130/0.4) on coagulation in patients undergoing major abdominal surgery.

UNLABELLED A new hydroxyethyl starch (HES) preparation with a mean molecular weight of 130,000 daltons and a degree of substitution of 0.4 shows favorable pharmacokinetic properties. We conducted a study of the influence of the new HES specification on coagulation and compared it with another colloidal intravascular volume replacement regimen using gelatin. According to a prospective, random sequence, 42 patients undergoing major abdominal surgery received either HES 130/0.4 (n = 21) or gelatin (n = 21) until the first postoperative day (POD) to keep central venous pressure between 10 and 14 mm Hg. From arterial blood samples, standard coagulation variables were measured, and modified thrombelastogram (TEG) measurements using different activators were performed. A total of 2830 +/- 350 mL of gelatin and 2430 +/- 310 mL of HES 130/0.4 were administered until the morning of the first POD. The use of allogeneic blood/blood products and standard coagulation variables did not differ significantly between the two groups. After induction of anesthesia, all TEG data for both groups were within normal range. Coagulation time and maximum clot firmness did not change significantly in any TEG measurements during the study period. The kinetics of clot formation (clot formation time) significantly increased immediately after surgery, but without showing significant group differences. On the morning of the first POD, the clot formation time returned to almost normal levels, except for aprotinin-activated TEG(R). We conclude that administration of moderate doses of the new HES 130/0.4 preparation in patients undergoing major abdominal surgery results in similar coagulation alterations as those after using an established gelatin-based volume-replacement regimen. IMPLICATIONS We compared the effects of infusion of a new hydroxyethyl starch preparation (6% hydroxyethyl starch; mean molecular weight 130,000 daltons; degree of substitution 0.4) on coagulation with a gelatin-based intravascular volume replacement regimen in patients undergoing major abdominal surgery. After moderate doses of hydroxyethyl starch (2430 +/- 310 mL until the morning of the first postoperative day), coagulation monitoring, including modified thrombelastography, did not show impaired hemostasis.

Cardiac output derived from arterial pressure waveform analysis in patients undergoing cardiac surgery: validity of a second generation device.

BACKGROUND The performance of a recently introduced, arterial waveform-based device for measuring cardiac output (CO) without the need of invasive calibration (FloTrac/Vigileo) has been controversial. We designed the present study to assess the validity of an improved version of this monitoring technique compared with intermittent thermodilution CO measurement using a pulmonary artery catheter in patients undergoing cardiac surgery. METHODS Forty ASA III patients scheduled for elective coronary artery bypass grafting with cardiopulmonary bypass (CPB) were studied. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device were obtained after induction of anesthesia (T1), before CPB (T2), after CPB (T3), after sternal closure (T4), on arrival in the intensive care unit (T5), 4 h (T6), 8 h (T7), and 24 h after surgery (T8). CO was indexed to the body surface area (cardiac index, CI). A percentage error of 30% or less was established as the criterion for method interchangeability. RESULTS Two hundred and eighty-two data pairs were analyzed. Thermodilution CI ranged from 1.2 to 4.1 L x min(-1) x m(-2) (mean 2.5 +/- 0.54 L x min(-1) x m(-2)). Bias and precision (1.96 sd of the bias) were 0.19 L x min(-1) x m(-2) and +/- 0.60 L x min(-1) x m(-2), resulting in an overall percentage error of 24.6%. Subgroup analysis revealed a percentage error of 28.3% for data pairs obtained intraoperatively (T1-4) and 20.7% in intensive care unit (T5-8). CONCLUSION CI values obtained by the improved, second generation semiinvasive arterial waveform device showed good intraoperative and postoperative agreement with intermittent pulmonary artery thermodilution CI measurements in patients undergoing coronary artery bypass graft surgery.

Volume replacement with HES 130/0.4 may reduce the inflammatory response in patients undergoing major abdominal surgery.

PURPOSE To investigate the effects of intravascular volume replacement therapy on the inflammatory response during major surgery. METHODS Thirty-six patients scheduled for elective abdominal surgery were randomized to receive either 6% hydroxyethylstarch (130,000 Dalton mean molecular weight, degree of substitution 0.4; n = 18, HES-group) or lactated Ringers solution (RL-group; n = 18) for intravascular volume replacement. Fluid therapy was given perioperatively and continued for 48 hr in the intensive care unit. Volume replacement was guided by physiological parameters. Serum concentrations of interleukin (IL)-6, IL-8 and IL-10 and soluble adhesion molecules (sELAM-1 and sICAM-1) were measured after induction of anesthesia, four hours after the end of surgery, as well as 24 hr and 48 hr postoperatively. RESULTS Biometric and perioperative data, hemodynamics and oxygenation were similar between groups. On average, 4470 +/- 340 mL of HES 130/0.4 per patient were administered in the HES-group compared to 14310 +/- 750 mL of RL in the RL-group during the study period. Release of pro-inflammatory cytokines IL-6 and IL-8 was significantly lower in the HES-group [(peak values) 47.8 +/- 12.1 pg*dL(-1) of IL-6 and 35.8 +/- 11.2 pg*mL(-1) of IL-8 (HES-group) vs 61.2 +/- 11.2 pg*dL(-1) of IL-6 and 57.9 +/- 9.7 pg*mL(-1) of IL-8 (RL-group); P < 0.05]. Serum concentrations of sICAM-1 were significantly higher in the RL-group [(peak values) 1007 +/- 152 ng*mL(-1) (RL-group) vs 687 +/- 122 ng*mL(-1), (HES group); P < 0.05)]. Values of sELAM-1 were similar in both groups. CONCLUSION Intravascular volume replacement with HES 130/0.4 may reduce the inflammatory response in patients undergoing major surgery compared to a crystalloid-based volume therapy. We hypothesize that this is most likely due to an improved microcirculation with reduced endothelial activation and less endothelial damage.

Natriuretic peptide system: physiology and clinical utility.

Purpose of reviewThis review discusses the physiology of natriuretic peptides as a group and brain natriuretic peptide (BNP) in more detail. It will also highlight implications for the use of the natriuretic peptides in the diagnosis and treatment of patients with cardiovascular disease. Recent findingsThe heart secretes two major natriuretic peptides: atrial natriuretic peptide (ANP), which is synthesized in the atrial myocardium, and BNP, which is synthesized in the ventricular myocardium. Both ANP and BNP are released in response to atrial and ventricular stretch, respectively, and will cause balanced vasodilation, natriuresis, and inhibition of the sympathetic nervous system and the renin–angiotensin–aldosterone axis. BNP is reported to be the biochemical marker of choice for evaluating the acute risk of patients with cardiovascular disease states ranging from heart failure to myocardial ischemia. Increased blood BNP concentrations are highly predictive of the short- and long-term risk of cardiac death across the entire spectrum of acute coronary syndromes and in patients with decompensated congestive heart failure. Synthetic recombinant human BNP, which mimics the actions of endogenous BNP, has emerged as an important new therapeutic agent in patients with acute heart failure. SummaryCurrent data suggest that single and serial plasma measurement of BNP concentrations is a useful tool in the diagnosis and risk stratification of patients with heart disease. Nesiritide, the human recombinant form of BNP, is a new promising parenteral treatment in decompensated heart failure.

The Influence of Allogeneic Red Blood Cell Transfusion Compared with 100% Oxygen Ventilation on Systemic Oxygen Transport and Skeletal Muscle Oxygen Tension After Cardiac Surgery: Retracted

In this study we investigated the effects of allogeneic red blood cell (RBC) transfusion on tissue oxygenation compared with those of 100% oxygen ventilation by using systemic oxygen transport variables and skeletal muscle oxygen tension (PtiO2). Fifty-one volume-resuscitated, mechanically ventilated patients with a nadir hemoglobin concentration in the range from 7.5 to 8.5 g/dL after elective coronary artery bypass grafting were allocated randomly to receive 1 unit (transfusion 1; n = 17) or 2 units (transfusion 2; n = 17) of allogeneic RBCs and ventilation with 40% oxygen or pure oxygen ventilation (100% oxygen; n = 17) and no allogeneic blood for 3 hours. Invasive arterial and pulmonary artery pressures and calculations of oxygen delivery (oxygen delivery index) and consumption indices (oxygen consumption index) were documented at 30-min intervals. PtiO2 was measured continuously by using implantable polarographic microprobes. Systemic oxygen transport variables and PtiO2 were similar between groups at baseline. The oxygen delivery index increased significantly with transfusion of allogeneic RBCs and 100% oxygen ventilation, whereas the oxygen consumption index remained unchanged. Oxygen 100% ventilation increased PtiO2 significantly (from 24.0 +/- 5.1 mm Hg to 34.2 +/- 6.2 mm Hg), whereas no change was found after transfusion of allogeneic RBCs. Peak PtiO2 values were 25.2 +/- 5.2 mm Hg and 26.3 +/- 6.5 mm Hg in the transfusion 1 and 2 groups, respectively. Transfusion of stored allogeneic RBCs was effective only in improving systemic oxygen delivery index, whereas 100% oxygen ventilation improved systemic oxygen transport and PtiO2. This improved oxygenation status was most likely due to an increase in convective oxygen transport with a large driving gradient for diffusion of plasma-dissolved oxygen into the tissue.

RETRACTED ARTICLE: Volume replacement with HES 130/0.4 may reduce the inflammatory response in patients undergoing major abdominal surgery

PURPOSE To investigate the effects of intravascular volume replacement therapy on the inflammatory response during major surgery. METHODS Thirty-six patients scheduled for elective abdominal surgery were randomized to receive either 6% hydroxyethylstarch (130,000 Dalton mean molecular weight, degree of substitution 0.4; n = 18, HES-group) or lactated Ringers solution (RL-group; n = 18) for intravascular volume replacement. Fluid therapy was given perioperatively and continued for 48 hr in the intensive care unit. Volume replacement was guided by physiological parameters. Serum concentrations of interleukin (IL)-6, IL-8 and IL-10 and soluble adhesion molecules (sELAM-1 and sICAM-1) were measured after induction of anesthesia, four hours after the end of surgery, as well as 24 hr and 48 hr postoperatively. RESULTS Biometric and perioperative data, hemodynamics and oxygenation were similar between groups. On average, 4470 +/- 340 mL of HES 130/0.4 per patient were administered in the HES-group compared to 14310 +/- 750 mL of RL in the RL-group during the study period. Release of pro-inflammatory cytokines IL-6 and IL-8 was significantly lower in the HES-group [(peak values) 47.8 +/- 12.1 pg*dL(-1) of IL-6 and 35.8 +/- 11.2 pg*mL(-1) of IL-8 (HES-group) vs 61.2 +/- 11.2 pg*dL(-1) of IL-6 and 57.9 +/- 9.7 pg*mL(-1) of IL-8 (RL-group); P < 0.05]. Serum concentrations of sICAM-1 were significantly higher in the RL-group [(peak values) 1007 +/- 152 ng*mL(-1) (RL-group) vs 687 +/- 122 ng*mL(-1), (HES group); P < 0.05)]. Values of sELAM-1 were similar in both groups. CONCLUSION Intravascular volume replacement with HES 130/0.4 may reduce the inflammatory response in patients undergoing major surgery compared to a crystalloid-based volume therapy. We hypothesize that this is most likely due to an improved microcirculation with reduced endothelial activation and less endothelial damage.

Diltiazem may preserve renal tubular integrity after cardiac surgery.

PURPOSE To evaluate the influence of dopamine and diltiazem on renal function and markers for acute renal failure, including urinary alpha-glutathion s-transferase (alpha-GST), alpha-1-microglobulin (alpha(1)-MG) and N-acetyl-ss-glucosaminidase (ss-NAG) after extracorporeal circulation. METHODS In a randomized, placebo-controlled, double-blind trial we evaluated the efficacy of dopamine (2.5 micro g x kg(-1) x min(-1)), diltiazem (2 micro g x kg(-1) x min(-1)) or placebo administered over 48 hr postoperatively to maintain renal tubular integrity in 60 elective cardiac surgery patients. alpha-GST, alpha(1)-MG, ss-NAG, and creatinine clearance were measured from urine collected during surgery (T0), the first four hours (T1), 24 hr (T2) and 48 hr (T3) postoperatively. RESULTS Cumulative urine output in the diltiazem group (9.0 +/- 2.8 L) increased significantly compared with placebo (7.0 +/- 1.6 L), but not compared with dopamine (7.8 +/- 1.8 L). Creatinine clearance showed no significant intergroup differences. In all groups alpha(1)-MG increased from T0 to T3, but we found no significant intergroup differences. alpha-GST increased significantly from T0 to T3 in the placebo (2.1 +/- 1.8 to 11.4 +/- 8.6 micro g x L(-1)) and in the dopamine groups (2.7 +/- 1.8 to 13.6 +/- 14.9 micro g x L(-1)), but not in the diltiazem group (1.8 +/- 1.4 to 3.2 +/- 3.2 micro g x L(-1)). Forty-eight hours postoperatively alpha-GST was significantly lower in the diltiazem group than in both other groups. CONCLUSIONS Diltiazem stimulates urine output, reduces excretion of alpha-GST and ss-NAG and may be useful to maintain tubular integrity after cardiac surgery.

A comparison of urapidil, clonidine, meperidine and placebo in preventing postanesthetic Shivering

UNLABELLED This placebo-controlled study was performed to evaluate the efficacy of urapidil compared with clonidine and meperidine in preventing postanesthetic shivering, which is common after anesthesia administration and may be very distressing. We studied 120 patients undergoing elective abdominal or orthopedic surgery under standardized general anesthesia. After surgery, patients were randomly assigned to one of four groups (each group n = 30) using a double-blinded protocol: Group A received 0.2 mg/kg urapidil; Group B, 3 microg/kg clonidine; Group C, 0.4 mg/kg meperidine; and Group D, saline 0.9% as placebo. Postanesthetic shivering was scored by using a five-point scale. Clonidine and meperidine significantly reduced the incidence and the severity of shivering in comparison with placebo, whereas there were no significant differences between the urapidil and placebo groups. Both clonidine and meperidine caused a significantly prolonged emergence time (13.4 +/- 5.8 and 13. 3 +/- 5.0 min, respectively) compared with placebo (10.4 +/- 5.3 min) and urapidil (11.4 +/- 2.9 min). We confirmed that both clonidine and meperidine are effective in preventing postanesthetic shivering, whereas urapidil, in our setting and dosage, was not effective. Patients who received clonidine or meperidine had a prolonged emergence time. In the dosage used, urapidil seems to be unable to prevent postanesthetic shivering. IMPLICATIONS Shivering (irregular muscle activity) is common after surgery and anesthesia. This study compared urapidil (an antihypertensive drug) as a prophylaxis with two established antishivering drugs (meperidine and clonidine) and placebo. In the dosage used, we were unable to show a significant benefit of urapidil.