Stefan-Mario Kasper

Effects of a hemoglobin-based oxygen carrier (HBOC-201) on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery

We conducted a pilot study to evaluate the effects of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After induction of anesthesia and isovolemic hemodilution with 1 L of lactated Ringers solution, 13 patients were randomly assigned to receive, within 30 min, 3 mL/kg of either HBOC-201 or 6% hydroxyethyl starch (HES). Monitored variables included invasive arterial and pulmonary artery pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic and pulmonary vascular resistance indices, oxygen delivery index (DO (2) I), oxygen consumption index (VO2 I), and oxygen extraction ratio (O2 ER). Thirty minutes after HBOC-201 infusion, mean arterial pressure, systemic vascular resistance index, and CI were 149% (P = 0.028), 169% (P = 0.046), and 75% (P = 0.046) of the preinfusion values, respectively. No significant changes were noticed in heart rate and pulmonary vascular resistance index. DO2 I and VO2 I, 30 min after the infusion of HBOC-201, were 79% (P = 0.046) and 76% (P = 0.028) of the preinfusion values, respectively, whereas CaO2 and O2 ER remained unaffected. We conclude that HBOC-201, at a dose of 3 mL/kg, impairs oxygen delivery because of adverse effects on cardiac output. (Anesth Analg 1996;83:921-7)

Large-dose hydroxyethyl starch 130/0.4 does not increase blood loss and transfusion requirements in coronary artery bypass surgery compared with hydroxyethyl starch 200/0.5 at recommended doses.

Background Hydroxyethyl starch (HES) 130/0.4 may impair blood coagulation less than other HES solutions and, thus, may be used at larger doses without increasing the risk of postoperative bleeding. This study tested the hypothesis that volume replacement with 6% HES 130/0.4 at a dose of up to 50 ml/kg does not increase blood loss and transfusion requirements in elective coronary artery bypass surgery compared with 6% HES 200/0.5 at a dose of up to 33 ml/kg. Methods One hundred twenty adult patients scheduled for elective coronary artery bypass surgery were randomized to receive up to 50 ml/kg of 6% HES 130/0.4 or up to 33 ml/kg of 6% HES 200/0.5 for volume replacement during surgery and until 24 h thereafter. Volume requirements in excess of the respective maximum dose of HES were treated with gelatin. Colloid use was at the discretion of the attending physicians and not dictated by protocol. The primary outcome variable was chest tube drainage volume during the first 24 h after surgery. Results The data from 117 patients (HES 130/0.4, 59 patients; HES 200/0.5, 58 patients) who completed the study according to protocol were analyzed. The median volumes of HES administered were 49 and 33 ml/kg in the HES 130/0.4 and HES 200/0.5 groups, respectively (P < 0.001). Consequently, patients in the HES 130/0.4 group required less gelatin in addition to HES than those in the HES 200/0.5 group (medians: 7 ml/kg vs. 20 ml/kg, P < 0.001). The combined volumes of HES and gelatin were similar for both groups (P = 0.21). The 24-h chest tube drainage (medians: 660 ml vs. 705 ml, P = 0.60) did not differ significantly between the groups, nor did transfusion outcome. Conclusion Six percent HES 130/0.4 at a median dose of 49 ml/kg did not increase blood loss and transfusion requirements in coronary artery bypass surgery compared with 6% HES 200/0.5 at a median dose of 33 ml/kg.

The Effects of Increased Doses of Bovine Hemoglobin on Hemodynamics and Oxygen Transport in Patients Undergoing Preoperative Hemodilution for Elective Abdominal Aortic Surgery

In two consecutive studies (Study A and Study B), we evaluated the effects of increasing doses of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After the induction of anesthesia and the exchange of 1 L of blood for 1 L of lactated Ringers solution, 24 patients (12 in each study) were randomly assigned to receive, within 30 min, a predetermined volume of either HBOC-201 or 6% hydroxyethyl starch (Study A 6.9 mL/kg; Study B 9.2 mL/kg). Monitored variables included systemic and pulmonary arterial pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic (SVRI) and pulmonary (PVRI) vascular resistance indices, oxygen delivery index (Do2 I), oxygen consumption index (Vo2 I), and oxygen extraction ratio (O2 ER). In both studies, the infusion of HBOC-201 was associated with increases in SVRI (Study A 121%; Study B 71%) and PVRI (Study A 70%; Study B 53%) and with a decrease in CI (29% both studies). Hemodilution with HBOC-201 maintained the arterial oxygen content at levels higher than hemodilution with hydroxyethyl starch, but the advantage of a greater oxygen-carrying capacity was offset by the increase in SVRI, with a resulting net decrease in both CI and Do2 I (Study A 30%; Study B 28%); Vo2 I was maintained by increased O2 ER. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch. Implications: Bovine hemoglobin in doses ranging between 55 and 97 g of hemoglobin increased vascular resistance and decreased cardiac output in anesthetized surgical patients. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch. (Anesth Analg 1998;87:284-91)

N-acetylcysteine prevents reactive oxygen species–mediated myocardial stress in patients undergoing cardiac surgery: results of a randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE Reactive oxygen species have been shown to contribute to myocardial stress in patients undergoing cardiac surgery, as demonstrated by myocardial 8-iso-prostaglandin-F(2)alpha and nitrotyrosine formation. We hypothesized that the reactive oxygen species scavenger N-acetylcysteine attenuates reactive oxygen species-mediated myocardial stress in patients undergoing cardiac surgery. METHODS Forty patients undergoing coronary artery surgery (mean age +/- SD, 66 +/- 9 years; 9 women and 31 men) were randomized to receive either N-acetylcysteine (100 mg/kg into cardiopulmonary bypass prime followed by infusion at 20 mg.kg(-1).h(-1), n = 20) or placebo (n = 20). Patients and clinical staff were blinded to group assignment. Transmural left ventricular biopsy specimens collected before and at the end of cardiopulmonary bypass were subjected to immunocytochemical staining against 8-iso-prostaglandin-F(2)alpha (primary measure) as an indicator for reactive oxygen species-mediated lipid peroxidation and nitrotyrosine (coprimary measure) as a marker for peroxynitrite-mediated tissue injury. Cardiomyocyte staining was quantitatively determined by using densitometry (in gray units). Global left ventricular function was measured on the basis of fractional area of contraction by using transesophageal echocardiography. RESULTS Patient characteristics in both groups were comparable. The change in left ventricular cardiomyocyte staining (end of cardiopulmonary bypass--before cardiopulmonary bypass) differed significantly between groups for both primary measures: 8-iso-prostaglandin-F(2)alpha, -1.8 +/- 7.5 gray units (mean +/- SD, N-acetylcysteine group) versus 5.0 +/- 4.1 gray units (placebo group; 95% confidence interval, 2.6-11.0, P =.003); nitrotyrosine, -6.4 +/- 10.0 gray units (N-acetylcysteine group) versus 9.2 +/- 8.4 gray units (placebo group; 95% confidence interval, 9.4-21.7, P <.001). Hemodynamics and clinical outcomes were comparable in both groups. CONCLUSIONS Reactive oxygen species scavenging with N-acetylcysteine attenuates myocardial oxidative stress in the hearts of patients subjected to cardiopulmonary bypass and cardioplegic arrest.

Impact of tranexamic acid vs. aprotinin on blood loss and transfusion requirements after cardiopulmonary bypass: a prospective, randomised, double-blind trial.

Summary Introduction: Aprotinin (AP) reduces blood loss and transfusions after cardiopulmonary bypass (CPB), but may sensitise patients and is expensive. Tranexamic acid (TA) has less side-effects, but data regarding its efficacy are controversial. The aim of our prospective, randomised, double-blind study was to compare the impact of AP vs. TA on drainage blood loss and transfusion requirements in patients undergoing first time CABG on CPB. Materials and Methods: One hundred and twenty adult patients were randomised to receive either high-dose AP according to Hammersmith or a total of 2 g TA. Perioperative blood products were transfused in a standardised fashion. Blood loss was measured up to 24 h. Demographic and clinical patient data were collected until hospital discharge. Results: The data from 118 patients (TA: n = 58, TA appears to be a cost-effective alternative to AP AP: n = 60) who completed the study according to protocol were analysed. Blood loss at 24 h postoperation in TA patients was significantly higher (896 ± 354 ml) as compared to AP patients (756 ± 347ml; p = 0.03). TA patients received 1.5 ± 1.5 units of red blood cells (AP: 1.5 ± 1.7, p = 1.0), 1.3 ± 2.0 units of fresh frozen plasma (AP: 1.0 ± 2.0, p = 0.38) and 0.5 ± 1.4 units of platelets (AP: 0.2 ± 0.7, p = 0.15). Clinical data, including perioperative myocardial infarction rate, acute renal failure, mechanical ventilation, hospital stay and mortality, were not significantly different between either group. Conclusion: Our data show a difference in blood loss between TA and high-dose AP. Although statistically significant, it has little clinical relevance, because perioperative transfusion requirements were similar for both groups. Thus, TA appears to be a cost-effective alternative to AP in primary CABG patients.

Transient Radicular Irritation After Spinal Anesthesia with Hyperbaric 4% Mepivacaine

reported after spinal anesthesia with the use of hyperbaric 5% lidocaine (l-3) and, rarely, with bupivacaine (4) and tetracaine (5). Hyperbaric 4% mepivacaine has been used for spinal anesthesia for many years (6), especially in Europe (7), and has so far not been implicated clinically in causing TRI. We present two cases of TRI symptoms after spinal anes-

The use of Quincke and Whitacre 27-gauge needles in orthopedic patients: incidence of failed spinal anesthesia and postdural puncture headache.

This study examined the incidence of failed spinal anesthesia and postdural puncture headache using a 27-gauge Whitacre and a 27-gauge Quincke needle in patients undergoing elective inpatient orthopedic procedures. The overall rate of failed spinal anesthesia was 8.5% [95% confidence interval (CI) = 4.6%-12.4%] (n = 17) in the Quincke group (n = 199) and 5.5% [95% CI = 2.3%-8.7%] (n = 11) in the Whitacre group (n = 199). This difference was not statistically significant. The overall incidence of postdural puncture headache (PDPH) was 0.8%; 1.1% [95% CI = 0%-2.4%] (n = 2) in the Quincke group and 0.5% [95% CI = 0%-1.5%] (n = 1) in the Whitacre group. These differences were not statistically significant. All headaches were classified as mild and resolved spontaneously with conservative management. The mean time for withdrawal of the stylet to appearance of cerebrospinal fluid was 10.8 +/- 6.9 s in the Quincke (n = 31) and 10.7 +/- 6.8 s in the Whitacre group (n = 33). These differences were not statistically significant. Our results suggest that both needles are associated with a very low incidence of PDPH and an incidence of failed anesthesia of 5.5%-8.5%.

All adverse events in autologous blood donors with cardiac disease are not necessarily caused by blood donation

BACKGROUND:Autologous blood donation before elective cardiac surgery has become a standard of care at many institutions. However, the safety of autologous blood donations by patients with cardiac disease is subject to controversy. CASE REPORTS: Two life‐threatening cardiac arrests and one fatal myocardial infarction that occurred in three patients who were scheduled to donate blood for autologous use in elective cardiac surgery are reported. All three patients met the institutions selection criteria for autologous blood donors, and all of them had given written informed consent for their participation in the autologous blood donation program. One of the two cardiac arrests and the myocardial infarction occurred in the patients prior to any blood donations, and the other cardiac arrest occurred 7 days after the patient donated blood uneventfully. CONCLUSION: Life‐threatening and fatal adverse events may occur during the donation period in autologous blood donors with cardiac disease. Not all adverse events are necessarily caused by blood donation.

Human Error: The Persisting Risk of Blood Transfusion: A Report of Five Cases

UNLABELLED It is common experience that virus transmission, particularly transmission of the human immunodeficiency virus (HIV), is a principal concern of patients and physicians regarding blood transfusion (1). Many physicians are probably unaware that transfusion-transmitted HIV infection is approximately 50 to 100 times less likely to occur than transfusion error (2-4). This misconception may have been encouraged by the scarcity of reports on transfusion error relative to the tremendous public attention focused on HIV infection. We present five cases illustrating how anesthesiologists, intensivists, and emergency physicians are particularly vulnerable to the risk of administering blood to the wrong recipient. All five cases were collected during a 4-yr period. Transfused units of packed red cells totaled approximately 50,000 U during this period in our department. IMPLICATIONS Human error leading to the transfusion of blood to an unintended recipient is a major source of transfusion-related fatalities. We report five cases that highlight some specific areas in which transfusion error is likely to occur.

Failure of Autologous Fresh Frozen Plasma to Reduce Blood Loss and Transfusion Requirements in Coronary Artery Bypass Surgery

BackgroundPrevious studies failed to demonstrate any benefit from prophylaxis with fresh frozen plasma (FFP) after cardiopulmonary bypass (CPB). The results, however, were limited by either retrospective study design or use of FFP in subtherapeutic doses (2–3 units). The authors evaluated whether a therapeutic dose (15 ml/kg) of FFP reduces blood loss and transfusion requirements in elective coronary artery bypass surgery. The risks of multiple allogeneic blood donor exposure were circumvented by using autologous plasma. MethodsSixty adult patients scheduled for elective primary coronary artery bypass grafting were randomized to receive, after CPB, an intravenous infusion of 15 ml/kg of either autologous FFP (30 patients) or 6% hydroxyethyl starch 450/0.7 (HES; 30 patients). Autologous plasma was obtained by platelet-poor plasmapheresis several weeks before surgery. Perioperative blood transfusions were administered per protocol. Postoperative blood loss was defined as the chest tube drainage during the first 24 h after surgery. ResultsThe data from 56 patients (FFP group, 27 patients; HES group, 29 patients) who completed the study according to protocol were analyzed. Median postoperative blood loss was 630 ml (range, 450–1,840 ml) and 830 ml (range, 340–1,980 ml) in the FFP and HES groups, respectively (P = 0.08). Both postoperative (0–24 h) and total perioperative erythrocyte transfusion requirements did not differ significantly between the groups (P = 0.32 and 0.14, respectively). ConclusionThe prophylactic administration of a therapeutic dose (15 ml/kg) of autologous FFP after CPB failed to reduce blood loss and transfusion requirements in patients undergoing uncomplicated, elective, primary coronary artery bypass surgery.