[Prevention of perioperative hypothermia : Implementation of the S3 guideline]. / Vermeidung perioperativer Hypothermie : Umsetzung der S3-Leitlinie.

To improve perioperative quality and patient safety, the German S3 guideline should be consistently implemented to avoid perioperative hypothermia. Perioperative normothermia is a quality indicator and should be achieved by anesthesiologists and surgeons. To detect hypothermia early during the perioperative process, measuring body temperature should be started 1-2 h preoperatively. Patients should be actively warmed for 20-30 min before starting anesthesia. Prewarming is most effective and should be included in the preoperative process. Patients should be informed about the risks of perioperative hypothermia and members of the perioperative team should be educated. A standard operating procedure (SOP) to avoid hypothermia should be introduced in every operative unit. The incidence of postoperative hypothermia should be evaluated in operative patients every 3-6 months. The goals should be to measure body temperature in >80% of patients undergoing surgery and for >70% to exhibit a core temperature >36 °C at the end of surgery.

The effect of short time periods of pre-operative warming in the prevention of peri-operative hypothermia.

The aim of our study was to evaluate the performance of different durations of active pre-operative skin-surface warming (pre-warming) to prevent peri-operative hypothermia and postoperative shivering. We randomly assigned 200 patients, scheduled for surgery of 30-90 min under general anaesthesia, to receive passive insulation or forced-air skin surface warming for 10, 20 or 30 min. Body temperature was measured at the tympanic membrane. Shivering was graded by visual inspection. There were significant differences in changes of core temperature between the non-pre-warmed group and all the pre-warmed groups (p < 0.00001), but none between the three pre-warmed groups (p = 0.54). Without pre-warming, 38/55 (69%) patients became hypothermic (< 36 °C) at the end of anaesthesia, whereas only 7/52 (13%), 3/43 (7%) and 3/50 (6%) patients following 10, 20 or 30 min pre-warming, respectively, became hypothermic (p < 0.001 vs no pre-warming). Shivering was observed in 10 patients without, and in three, three and one patients with pre-warming in the respective groups (p = 0.02). Pre-warming of patients for only 10 or 20 min before general anaesthesia mostly prevents hypothermia and reduces shivering.

Effects of isovolaemic haemodilution on oxygenation of liver and skeletal muscle.

BACKGROUND AND OBJECTIVE: Hydroxyethyl starch is frequently used for volume substitution during surgical procedures and for isovolaemic haemodilution. Haemodilution has also been shown to improve tissue oxygen tension in skeletal muscle: However, effects of this volume substitute on tissue oxygen tension of the liver during haemodilution remains unknown. METHODS: Fourteen foxhounds were anaesthetized with fentanyl/midazolam and mechanically ventilated with 30% oxygen. Following splenectomy animals were randomly assigned to a control group without haemodilution but fluid substitution with Ringer's lactate (Group C) or underwent isovolaemic haemodilution to a haematocrit of 25% with hydroxyethyl starch 70/0.5 (Group H). Haemodynamic parameters and oxygen transport during 100 min following isovolaemic haemodilution were measured. Liver oxygen tension was recorded using a flexible polarographic electrode tonometer, whereas in the muscle a polarographic needle probe was used. RESULTS: Animal characteristics and baseline haematocrit were similar in both groups. At baseline the tissue oxygen tension of liver and skeletal muscle were not different between groups. Haemodilution with hydroxyethyl starch 70/0.5 provided augmentation of mean liver tissue oxygen tension (baseline: 46 +/- 13 mmHg; 20 min: 60.3 +/- 12 mmHg; 60 min: 60 +/- 16 mmHg; 100 min: 63 +/- 16 mmHg; P < 0.05 vs. baseline), while oxygen tensions in Group C remained unchanged (baseline: 48 +/- 16 mmHg; 20 min: 52 +/- 19 mmHg; 60 min: 49 +/- 12 mmHg; 100 min: 52 +/- 16 mmHg) and no differences could be detected between groups. Oxygen tension in skeletal muscle changed as follows: Group H - baseline: 24 +/- 32 mmHg; 20 min: 32 +/- 3 mmHg; 60 min: 33 +/- 7 mmHg; 100 min: 33 +/- 11 mmHg. Group C - baseline: 22 +/- 6 mmHg; 20 min: 21 +/- 3 mmHg; 60 min: 24 +/- 4 mmHg; 100 min: 18 +/- 4 mmHg (P < 0.05 vs. baseline, p < 0.05 vs. Group C). CONCLUSION: In this animal model, isovolaemic haemodilution with hydroxyethyl starch 70/0.5 increased tissue oxygen tension in liver and skeletal muscle in comparison with baseline values. However, when compared between groups haemodilution only resulted in an increase of tissue oxygen tension in the muscle but not in the liver.

Hemoglobin-based oxygen carrier HBOC-201 provides higher and faster increase in oxygen tension in skeletal muscle of anemic dogs than do stored red blood cells.

BACKGROUND: Increasing need for and potential shortage of blood products have intensified the search for alternative oxygen carriers. A solution to this problem could be use of the bovine hemoglobin-based oxygen carrier HBOC-201. While hemodynamic reactions to cell-free hemoglobin have been studied, little knowledge exists about tissue oxygenation properties of hemoglobin solutions, especially in comparison with red blood cells (RBCs). STUDY DESIGN AND METHODS: Tissue oxygenation in skeletal muscle of 12 anesthetized dogs was examined after decrease of hemoglobin concentrations by means of hemodilution to hematocrit 10% and subsequent transfusion with either HBOC-201 or autologous banked RBCs. In addition to hemodynamic parameters, blood gas concentrations and oxygen content in arterial and muscular venous blood, tissue oxygen tension (tPO(2)) were measured in the gastrocnemius muscle with a polarographic needle probe. RESULTS: Hemodilution increased muscular blood flow and oxygen extraction and decreased tPO(2). Transfusion decreased muscular oxygen extraction in the RBC group but not in the HBOC-201 group (P <.01). The 10th percentile of tPO(2) increased by 400% after the first dose of HBOC-201 (P <.001 vs posthemodilution) but only by 33% after equivalent RBC transfusion (P <.01 vs HBOC-201). Increases in the 50th (120%, P <.05) and 90th (31%) percentiles and all percentiles of tPO(2) after the second and third HBOC-201 dose were less pronounced but higher than in the RBC group. CONCLUSION: Compared with RBC transfusion, infusion of low doses of HBOC-201 maintain enhanced oxygen extraction after extended hemodilution and provide faster and higher increase in muscular tissue PO(2).

Acute normovolaemic haemodilution beyond a haematocrit of 25%: ratio of skeletal muscle tissue oxygen tension and cardiac index is not maintained in the healthy dog.

BACKGROUND AND OBJECTIVE: The study investigated the effect of acute normovolaemic haemodilution on haemodynamics, blood flow and oxygen transport variables with regard to skeletal muscle tissue oxygenation in a canine model. METHODS: Twenty foxhounds were anaesthetized, mechanically ventilated with 30% oxygen in air and underwent first-step normovolaemic haemodilution with Ringer's lactate solution to haematocrit (Hct) 30 and 25% and second-step acute normovolaemic haemodilution with 6% Hetastarch 70,000/0.5 to Hcts of 20, 15 and 10%. Catheters were inserted into femoral arteries and veins and into the pulmonary artery for measurements ofhaemodynamics, temperature, and sampling of arterial and mixed-venous blood. A flow probe was placed around the left femoral artery. Skeletal muscle tissue oxygen tension (tPO2) was measured in the gastrocnemius muscle using a stepwise driven polarographic needle probe creating histograms from 200 single tPO2 measurements. RESULTS: Until a Hct of 25% was reached, the heart rate, mean arterial pressure, global and muscular oxygen delivery and consumption remained constant, while the cardiac index and oxygen extraction ratio were significantly increased when compared with baseline. The median tPO2 was significantly decreased at Hcts 15 and 10%, despite increased cardiac index and regional blood flow. The ratio of tPO2 and cardiac index as a marker for efficiency of acute normovolaemic haemodilution started to decline beyond Hcts of 25% (change of slope). CONCLUSIONS: In acute normovolaemic haemodilution to the level of Hct of 25%, the ratio between tPO2 and cardiac index decreases in the healthy dog, indicating an uneconomic relation at the threshold of Hct of 25%.

[Analgosedation, analgesia with remifentanil in incontinence surgery via tension-free vaginal tape]. / Analgosedierung bzw. Analgesie mit Remifentanil bei Inkontinenz-Operationen mittels Urethraschlingenplastik (TVT).

OBJECTIVE: The tension-free vaginal tape operation (TVT) is a new surgical treatment of stress urinary incontinence in women. The tape has to be placed at the level of midurethra in the left and right paraurethral canal and has to be brought up to the abdominal wall in close contact with the back of the pubic bone with a special needle instrument. The performed anesthesia is decisive for the operative success, because a sufficient analgesia is demanded and, on the other hand, the correct placement and tension of the urethral tape has to be controlled by the patient performing a stress test by coughing and pressing. In this context the opioid remifentanil seems to be specially suitable because of its pharmacologic characteristics. METHODS: In this retrospective analysis the anesthesia related data of a total of 70 patients undergoing TVT surgery with remifentanil analgesia within one year were reviewed according to their anesthesia protocols. RESULTS: All patients underwent remifentanil analgesia in combination with local anesthesia. In no case the performed procedure had to be changed. In 7 cases a temporary decrease of the pulsoximetrically measured oxygen saturation to less-than-or-equal 92 % occurred, which could be treated by reduction of the infusion rate of remifentanil or by assisted ventilation. All patients were adequately able to perform the intraoperatively required stress test. 16 patients suffered from nausea and/or vomiting postoperatively. CONCLUSION: Continuous infusion of remifentanil is suitable for the short time profound analgesia needed for the TVT operation because of the pharmacologic characteristics of remifentanil. A antiemetic prophylaxis should be performed with this analgetic regime.

Soccer ball-related retinal injuries: a report of 13 cases.

PURPOSE: To describe the clinical characteristics and management of retinal injuries caused by soccer ball impact as well as the mechanism of injury, prognostic features, risk factors, and possible prevention strategies. METHODS: Thirteen cases of soccer ball injuries from retina referral practices were retrospectively reviewed, with attention to the mechanism of associated ocular complications and the anatomic and visual outcomes. RESULTS: Soccer ball injuries occurred in both male and female patients (9 male, 4 female) with ages ranging from 8 to 21 years (median 14 years). These patients were observed from 0 to 64 months (median follow-up, 8 months). Four patients had traumatic macular holes, two eyes had retinal detachment associated with retinal dialysis, two had retinal tears associated with hemorrhage, one had a choroidal rupture, and one had only vitreous hemorrhage and Berlin's edema. Although six eyes had some degree of traumatic retinal pigment epitheliopathy, it was the primary diagnosis in only three. Visual acuity at presentation ranged from 20/20 to count fingers, with 7/13 (54%) having 20/200 or worse vision. Seven eyes underwent surgical procedures; the remainder were observed. Final visions ranged from 20/20 to count fingers, with 3/13 (23%) having 20/200 or worse vision. Six eyes (46%) improved by two or more lines by the last follow-up. CONCLUSION: Soccer ball-related ocular injuries disproportionately affect young players, are more frequent in females than previously reported, and have more severe visual consequences than previously recognized. Injury prevention strategies to minimize contact between the eye and the soccer ball may reduce the incidence and severity of eye injuries.

Supplemental perioperative oxygen to reduce the incidence of surgical-wound infection.

BACKGROUND: Destruction by oxidation, or oxidative killing, is the most important defense against surgical pathogens and depends on the partial pressure of oxygen in contaminated tissue. An easy method of improving oxygen tension in adequately perfused tissue is to increase the concentration of inspired oxygen. We therefore tested the hypothesis that the supplemental administration of oxygen during the perioperative period decreases the incidence of wound infection. METHODS: We randomly assigned 500 patients undergoing colorectal resection to receive 30 percent or 80 percent inspired oxygen during the operation and for two hours afterward. Anesthetic treatment was standardized, and all patients received prophylactic antibiotic therapy. With use of a double-blind protocol, wounds were evaluated daily until the patient was discharged and then at a clinic visit two weeks after surgery. We considered wounds with culture-positive pus to be infected. The timing of suture removal and the date of discharge were determined by the surgeon, who did not know the patient's treatment-group assignment. RESULTS: Arterial oxygen saturation was normal in both groups; however, the arterial and subcutaneous partial pressure of oxygen was significantly higher in the patients given 80 percent oxygen than in those given 30 percent oxygen. Among the 250 patients who received 80 percent oxygen, 13 (5.2 percent; 95 percent confidence interval, 2.4 to 8.0 percent) had surgical-wound infections, as compared with 28 of the 250 patients given 30 percent oxygen (11.2 percent; 95 percent confidence interval, 7.3 to 15.1 percent; P=0.01). The absolute difference between groups was 6.0 percent (95 percent confidence interval, 1.2 to 10.8 percent). The duration of hospitalization was similar in the two groups. CONCLUSIONS: The perioperative administration of supplemental oxygen is a practical method of reducing the incidence of surgical-wound infections.

Wound infiltration and drain lavage with ropivacaine after major shoulder surgery.

UNLABELLED: Subcutaneous infiltration and wound lavage with ropivacaine is an alternative to opioids after major shoulder surgery. However, the efficacy and potential toxicity of this method remain unclear. We therefore evaluated plasma ropivacaine concentrations after shoulder infiltration and wound lavage. We subsequently quantified the efficacy of two ropivacaine concentrations. Patients undergoing major shoulder surgery were anesthetized with alfentanil and propofol. The initial patients (n = 18) received ropivacaine 7.5 mg/mL and ropivacaine plasma concentrations were measured in 15-min intervals. The subsequent 45 patients were randomly assigned to: 1) isotonic saline, 2) 3.75 mg/mL ropivacaine, or 3) 7.5 mg/mL ropivacaine. Ten milliliters of each solution was administered subcutaneously and 20 mL was injected into the wound drain which was clamped for 10 min. Supplemental postoperative pain relief was provided by patient-controlled anesthesia using the opioid piritramid (3.5-mg boluses, 6-min lock-out). Postoperative pain scores were recorded on a 100-mm visual analog scale for 4 h in the initial patients and for 10 h in the second part of the study. Unbound ropivacaine plasma concentrations peaked after 15 min at 0.08+/-0.09 microg/mL; the maximum was 0.30 microg/mL, compared with a toxic threshold of 0.6 microg/mL. In the second part of the study, pain scores were significantly lower after 3.75 mg/mL (20+/-15 mm) or 7.5 mg/mL (10+/-9 mm) ropivacaine than saline (35+/-10 mm). Piritramid requirements differed significantly in the three groups, being highest with saline and lowest with ropivacaine 7.5 mg/mL. We conclude that wound infiltration and lavage with 30 mL ropivacaine 7.5 mg/mL after major shoulder surgery resulted in very low pain scores and opioid requirement. IMPLICATIONS: Wound infiltration and lavage with 30 mL ropivacaine 7.5 mg/mL after major shoulder surgery resulted in very low pain scores and opioid requirement.

Postoperative pain facilitates nonthermoregulatory tremor.

BACKGROUND: Spontaneous tremor is relatively common in normothermic patients after operation and has been attributed to many causes. The hypothesis that nonthermoregulatory shivering-like tremor is facilitated by postoperative pain was tested. In addition, the effects of intravenous lidocaine on nonthermoregulatory tremor were evaluated. METHODS: Patients undergoing knee surgery were anesthetized with 2 microg/kg intravenous fentanyl and 0.2 mg/kg etomidate. Anesthesia was maintained with 1.7 +/- 0.8% (mean +/- SD) isoflurane. Intraoperative forced-air heating maintained normothermia The initial 44 patients were randomly allocated to receive an intra-articular injection of 20 ml saline (n = 23) or lidocaine, 1.5% (n = 21). The subsequent 30 patients were randomly allocated to receive an intravenous bolus of 250 microg/kg lidocaine followed by an infusion of 13 microg x kg(-1) x h(-1) lidocaine or an equivalent volume of saline when shivering was observed. Patient-controlled analgesia was provided for all patients: 3.5 mg piritramide, with a lockout interval of 5 min, for an unlimited total dose. Shivering was graded by a blinded investigator using a four-point scale. Pain was assessed by a 100-mm visual analog scale (0 = no pain and 100 = worst pain). The arteriovenous shunt status was evaluated with forearm-minus-fingertip skin-temperature gradients. RESULTS: Morphometric characteristics and hemodynamic responses were similar in the four groups. Core and mean skin temperature remained constant or increased slightly compared with preoperative values, and postoperative skin-temperature gradients were negative (indicating vasodilation) in nearly all patients. After intra-articular injection of saline, pain scores for the first postoperative hour averaged 46 +/- 32 mm (mean +/- SD), and 10 of the 23 (43%) patients shivered. In contrast, the pain scores of patients who received intra-articular lidocaine were significantly reduced to 5 +/- 9 mm and shivering was absent in this group (P < 0.05). In the second portion of the study, neither intravenous lidocaine nor saline reduced the magnitude or duration of nonthermoregulatory tremor or the patients' pain scores. CONCLUSIONS: Intra-articular, but not intravenous, lidocaine reduced surgical pain and prevented nonthermoregulatory shivering. Therefore, these data indicate that postoperative pain facilitates nonthermoregulatory shivering.

[Intraoperative normothermia with partial warming of patients undergoing orthopedic procedures]. / Intraoperative Normothermie durch partielle Wärmung von Patienten während orthopädischer Operationen.

OBJECTIVE: This study investigates if warming of the upper or lower half of the body preserves normothermia in patients undergoing major orthopaedic surgery. Additionally, we compared the intraoperative tympanic membrane and urinary bladder temperatures of these patients. METHODS: Fifty-four patients undergoing major orthopaedic operations were observed. In all patients general anaesthesia was induced with fentanyl, etomidate, and atracurium and was maintained with isoflurane and nitrous oxide. Thirty patients were randomly allocated to maintain normal body temperatures (WarmTouch 5000. Mallinckrodt Medical, level IV, 41-42 degrees C), whereas 24 patients were not actively warmed. Warming of the patients was performed by complete body heating preoperatively and warming of the upper (n = 19) or lower (= 11) half of the body intraoperatively. Core temperature was recorded from the tympanic membrane. The urinary bladder temperature was measured by a special urinary catheter. RESULTS: Without active warming of the patients the core temperature decreased 1.6 degrees C during surgery. Core temperature remained constant in all actively heated patients, regardless of upper or lower body heating. Hypothermia of the unwarmed patients was detected by both, tympanic membrane measurement and--with a short delay--the urinary bladder temperature probe. CONCLUSION: This data suggests that active warming of the upper or lower half of the body during major orthopaedic surgery can preserve normothermia in all patients. During these surgical procedures the urinary bladder temperature was able to represent reliable core temperatures.

Postoperative shivering: aetiology and treatment.

Most postanaesthetic shivering-like tremor is normal thermoregulatory shivering in response to core hypothermia. Therefore, shivering will be prevented by maintaining intraoperative normothermia. Other thermoregulatory-related shivering is caused by the release of cytokines by the surgical procedure. Non-thermoregulatory shivering, occurring in normothermic patients, is caused by other aetiologies such as postoperative pain. It is thus likely that adequate treatment of postoperative pain will ameliorate non-thermoregulatory tremor. In addition, the administration of antipyretic drugs reduces shivering in patients after cardiopulmonary bypass surgery.

Non-thermoregulatory shivering in patients recovering from isoflurane or desflurane anesthesia.

BACKGROUND: Although cold-induced shivering is an obvious source of postanesthetic tremor, other causes may contribute. Consistent with this theory, the authors had previously identified an abnormal clonic component of postoperative shivering and proposed that it might be nonthermoregulatory. A subsequent study, however, failed to identify spontaneous muscular activity in normothermic volunteers. These data suggested that the initial theory was erroneous or that a yet-to-be identified factor associated with surgery might facilitate shivering in patients after operation. Therefore, the authors tested the hypothesis that some postoperative tremor is nonthermoregulatory. METHODS: One hundred twenty patients undergoing major orthopedic operation were observed. They were grouped randomly to receive maintenance anesthesia with nitrous oxide and isoflurane (0.8 +/- 0.4%) or desflurane (3.4 +/- 1.1%). Twenty patients in each group were allowed to become hypothermic, whereas normal body temperatures were maintained in the others (tympanic membrane temperature exceeding preinduction values). Arteriovenous shunt vasoconstriction was evaluated using forearm-minus-fingertip skin-temperature gradients; gradients less than 0 degrees C identified vasodilation. Postanesthetic shivering was graded by a blinded investigator. Tremor in patients who were normothermic and vasodilated was considered nonthermoregulatory. RESULTS: Thermoregulatory responses were similar after isoflurane or desflurane anesthesia. Approximately 50% of the unwarmed patients shivered. Shivering was observed in 27% of the patients who were normothermic; 55% of this spontaneous muscular activity occurred in vasodilated patients. Among the normothermic patients, 15% fulfilled the authors' criteria for nonthermoregulatory tremor. CONCLUSIONS: The incidence of postoperative shivering is inversely related to core temperature. Therefore, it was not surprising that shivering was most common among the hypothermic patients. The major findings, however, were that shivering remained common even among patients who were kept scrupulously normothermic and that many shivered while they were vasodilated. Thus, postoperative patients differ from nonsurgical volunteers in demonstrating a substantial incidence of nonthermoregulatory tremor.

Bovine haemoglobin-based oxygen carrier for patients undergoing haemodilution before liver resection.

We have studied the use of ultrapurified polymerized bovine haemoglobin (HBOC-201) in patients undergoing preoperative haemodilution before liver resection. After autologous blood donation of 1 litre, 12 patients (six males, six females, mean age 59 (35-69) yr) received Ringer's lactate solution 2 litre and, in a random design, 6% hydroxyethyl starch 70,000/0.5 (HES) 3 ml kg-1 or HBOC-201 0.4 g kg-1 within 30 min. Blood samples were obtained for blood chemistry, co-oximetry, haematology, coagulation profiles and immunology examinations before operation, on the day of surgery, on days 2-4 and 7 after operation, on the discharge day and 3 months after operation. There were no differences in patient characteristics, blood loss, amount of solutions infused, transfused allogeneic blood or duration of hospital stay. There were no local or systemic allergic reactions with infusion of HES or HBOC-201. Patients receiving HBOC-201 developed more pronounced leucocytosis and reticulocytosis during the early postoperative days compared with HES-treated patients. The mean maximum plasma haemoglobin concentration was 1.0 (SD 0.2) g dl-1 at the end of infusion of HBOC-201 was 8.5 h. Patients in both groups experienced temporary changes in liver enzymes and coagulation variables which returned to normal before discharge. Urinalysis revealed no difference between groups and no free haemoglobin was detected in urine. Patients receiving HBOC-201 showed no IgE and only a slight increase in IgG titres to HBOC-201 on the day of discharge; these were not detectable at 3 months. Single-dose administration of HBOC-201 was well tolerated by patients undergoing elective liver resection surgery and appears to be safe as a substitute during preoperative haemodilution.

[Bovine hemoglobin. HBOC-201 causes a reduction of the oxygen partial pressure in poststenotic skeletal muscle]. / Bovines Hämoglobin. HBOC-201 verhindert eine Reduktion des Sauerstoffpartialdrucks im poststenotischen Skelettmuskel.

UNLABELLED: We investigated the effects of ultrapurified polymerized bovine hemoglobin (HBOC-201) on skeletal muscle tissue oxygen tension when applied before establishment of a nearly complete arterial stenosis. METHODS: Twelve foxhounds were anaesthetized IV and mechanically ventilated with 30% oxygen in air. Catheters were inserted into the right femoral artery and vein for measurements of haemodynamic parameters and blood-gas sampling. Arterial blood flow of the left popliteal artery was measured by an electromagnetic flow probe. Skeletal muscle tissue oxygen tension (tpo2) was measured in the left gastrocnemic muscle using a stepwise-driven polarographic needle probe, creating histograms from 200 single tpO2 measurements. Following isovolaemic haemodilution with Ringer's solution to a target haematocrit of 20%, the animals were randomly assigned to receive either 200 ml of predonated fresh blood (group 1) or 200 ml of HBOC-201 (MW 32,000-500,000; Hb 13 +/- 1 g-dl-1, group 2). After a 15-min stabilization period, a 95% artificial stenosis of the left popliteal artery was established. While animals of group 1 received two applications of 200 ml 6% hetastarch (HES, 200,000; 0.5), animals of group 2 received 200 ml Ringer's solution 45 and 75 min after establishment of the arterial stenosis, respectively. Variables were measured at baseline, after haemodilution and application of the respective compound, and 30, 60 and 90 min after establishment of the stenosis. RESULTS: Demographic data, muscle temperature and arterial blood gases did not differ between groups. With the exception of a higher mean pulmonary artery pressure in HBOC-201-treated animals, haemodynamics did not differ between groups. In both groups oxygen delivery and oxygen consumption of the muscle decreased in parallel to the decreasing blood flow during arterial stenosis. In contrast, oxygen extraction ratio increased after infusion of HBOC-201 and remained unchanged during stenosis (P < 0.05). In group 1, the tpO2 decreased during stenosis when compared to baseline (P < 0.001) and remained decreased after administration of HES. In contrast, administration of 200 ml of HBOC-201 before establishment of the arterial stenosis sustained the tpO2 values at nearly baseline levels during stenosis. Skeletal muscle tissue oxygen tension was higher after HBOC-201 infusion during stenosis when compared to HES infusion (P < 0.001). CONCLUSION: These data suggest that haemoglobin solutions can reach poststenotic tissues. The increased oxygen extraction after application of HBOC-201 is associated with improved skeletal muscle oxygen tension during severe arterial stenosis.