Oxygen Transport Capacity and Hemodynamic Effect of Newly Developed Artificial Blood “Neo Red Cells (NRC)”

The purpose of this study was to evaluate liposome-encapsulated hemoglobin, named Neo Red Cells (NRC), on hemodynamics and oxygen-transport capacity in a blood exchange experiment. The experiment was carried out in nine mongrel dogs. Depending on the percentage of blood exchange with NRC, the animals were divided into two groups; Group I (4 animals with an exchange rate less than 88%), and Group II (5 animals with an exchange rate over 88%). After blood exchange, total peripheral vascular resistance index (TPRI) decreased and cardiac index (CI) increased. These changes were more marked in Group II than in Group I, thus showing that NRC relieved the burden on the heart, probably due to the fact that the viscosity of NRC is 2 cp which is less than 1/3 that of whole blood. The oxygen binding capacity per 1g hemoglobin in NRC was 2-4 times as much as red blood cells. Thus, NRC was superior to natural red blood cells in terms of oxygen transport capacity and its effects on the circulatory system.

Effect of Neo Red Cells on the Canine Hemorrhagic Shock Model

This study evaluated the newly developed artificial red blood cells named Neo Red Cells (NRC) after hemorrhagic shock in mongrel dogs. NRC is prepared as microcapsules by a method in which stroma-free hemoglobin is encapsulated using a bimolecular lipid membrane called liposome. The particle size is 0.2 μm, methemoglobin content is less than 5% and the hemoglobin concentration is 5.6 g/dl.

We analyzed blood gases and hemodynamics and carried out laboratory examinations after 59-88% blood exchange using NRC. The hemodynamic parameters returned to the normal range after NRC. Inhaling normal room air, oxygen carried by NRC was 60.40% at the exchange rate of 88%. Renal and hepatic function and other laboratory findings were normal after administration of NRC. After further study and improvement NRC could be considered suitable as artificial blood for treatment of hemorrhagic shock.

Effect of liposome-encapsulated hemoglobin, neo red cells, on hemorrhagic shock

We examined the effects of liposome-encapsulated hemoglobin, neo red cells (NRCs), on hemorrhagic shock in a canine model. The dogs were divided into the three groups according to treatment. In group 1, composed of six dogs, NRCs were substituted for blood without shock being induced; in group 2, composed of six dogs, NRCs were administered immediately after mild shock had been induced by exsanguination through the vein; and in group 3, composed of seven dogs, NRCs were administered after they had been left untreated for 30 min inducing severe shock. In group 2, administration of NRCs at a dose equivalent to the volume of exsanguinated blood improved the symptoms of shock; however, in group 3, a dose of NRCs 1.6-times the volume of exsanguinated blood was required. Peripheral vascular resistance (PVR) decreased after NRC administration in groups 1 and 2, but increased in group 3. On the other hand, the cardiac index (CI) increased in groups 1 and 2, and decreased in group 3. Concerning oxygen kinetics, there were no increases in the oxygen requirements or arteriovenous differences of the oxygen content per hemoglobin (AV/Hb) for NRCs in groups 1 and 2. Conversely, in group 3, the oxygen requirements increased and the NRCs compensated for the decrease in CI with an increase in AV/Hb by enhancing the oxygen transport efficiency to cope with the increased oxygen requirements.

Coronary vascular bed perfusion with a polyethylene glycol-modified hemoglobin-encapsulated liposome, neo red cell, in rats

Whether hemoglobin (Hb) encapsulated liposomes have vasoconstrictive activity remains controversial. We therefore examined the vascular activity of a liposome Hb, Neo red cell (NRC), in a simple in vitro model of Langendorff perfusion of the rat heart using Krebs-Henseleit (KH) solution as the perfusate. In the KH solution, NRC (Hb at 1 mg/ml), however, induced an immediate and abnormal increase in perfusion pressure. Histological examinations revealed that embolisms were the likely cause of this disturbance. Inorganic crystals formed by the mixing of NRC with the perfusate were a possible source of the embolisms. We found that the addition of bovine serum albumin to the perfusate was effective in avoiding embolic events. This protocol was used to compare the vasoconstrictive properties of unmodified bovine Hb and NRC. Unmodified bovine Hb (1 mg/ml) caused an increase in perfusion pressure and a decrease in the duration of bradykinin-induced relaxation. In contrast, NRC (Hb at 1 mg/ml) had no such vasoconstrictive effects. These results provide the first information regarding perfusion of the circulatory vascular bed by NRC and further evidence that the encapsulation of Hb into liposomes is an effective approach to modulate Hb-related vasoconstrictive activity.

Liposome encapsulated hemoglobin as a resuscitation fluid for hemorrhagic shock

The effectiveness of the blood substitute neo red cells (NRC) on hemorrhagic shock was evaluated in dogs. Shock was induced by bloodletting, and NRC was infused immediately until the dogs recovered from shock; the process was repeated 3 times (mild shock), or NRC was infused after shock was maintained for 30 min, and the process was repeated 3 times (severe shock). In mild shock, NRC with low viscosity reduced the peripheral vascular resistance and increased the cardiac index. However, in severe shock, only a slight decrease in the peripheral vascular resistance and no increase in the cardiac index were observed. In severe shock, the total oxygen consumption increased, but red blood cells or plasma did not change the oxygen transport and did not meet the increased oxygen demand. However, the NRC increased the oxygen transport and supplied the increased oxygen demand. In mild shock on the other hand, no increase was observed in the total oxygen consumption or the oxygen transport.

Effect of liposome encapsulated hemoglobin "neo red cells" on severe hemorrhagic shock

We induced shock by exsanguination and administered Neo Red Cells (NRC) after 30 minutes to experimentally examine the efficacy of NRC on severe shock with respect to hemodynamics and oxygen transport capacity. Seven beagles were used for this experiment. After intravenous anesthesia, intratracheal intubation was performed, and inhalation of 50% oxygen was administered. Animals were exsanguinated through a vein at a rate of 30 mL/min. Animals showing systolic blood pressure of 60 to 69 mmHg were regarded as being in shock. After animals were left untreated for 30 minutes, NRC was administered. This was then repeated. Administration of NRC at a 1.5-fold dose compared to the exsanguinated blood volume was required for animals to recover from shock. Animals tolerated shock 3 times, but did not recover from the 4th shock. Although NRC with approximately one third the viscosity of whole blood was administered, vascular resistance was increased and cardiac output was decreased, resulting in progression of heart failure. In addition, oxygen consumption increased with shock. NRC satisfied oxygen requirements by compensating for the decrease in cardiac output with an increase in AV difference, but erythrocytes were insufficient to increase difference in arterial and venous oxygen content (AV difference), and did not supply sufficient volume of oxygen.

[Respiratory failure after surgery for esophageal cancer and hypercoagulability]

Operation of esophageal cancer accompanies a big surgical stress and postoperative pulmonary complications such as respiratory failure are observed at high frequencies. On the other hand, when a big stress is added to a body, a state of hypercoagulation in which blood coagulation mechanism is abnormally enhanced appears and this state is closely related to organ failures but has many unknown points. So, we examined 39 patients given excision of esophageal cancer with respect to occurrence of postoperative respiratory failures, participation of coagulopathy in aggravation and their degrees before and after the operation to find out the relationship between postoperative respiratory failure and the state of hypercoagulation. We gave a diagnosis of respiratory failure to the patients whose respiratory index exceeded 1.5 on the day after operation but did not show atelectasis or hydrothorax. As a result, respiratory failures were observed in 7 out of 39 cases (17.9%). When a risk score (RS) of postoperative respiratory failure was determined using multivalent analysis (quantification type II) with preoperative factors such as age and function of heart, lung, liver, and kidney as well as preoperative blood coagulation factors, RS = 2.87 (antithrombin-III (AT-III) less than 75%) +1.89 (age over 70 years) +1.78 (respiratory index over 0.15) +1.44 (serum albumin less than 3.0 mg/dl) +1.28 (cardiac index less than 3.0 l/min/m2) was obtained and a drop in preoperative AT-III was considered a risk for occurrence of post operative respiratory failure. In contrast, referring changes in postoperative value of blood coagulation factors, a distinct rise in fibrinogen (FBG) appeared in early stage after operation in the respiratory failure group compared to the control group (p < 0.01). Moreover, recovery in AT-III of blood coagulation factors and in plasminogen and antiplasmin of fibrinolytic factors was delayed (p < 0.05) indicating promotion of postoperative hypercoagulation state and delay in recovery of coagulation-fibrinolysis factors. However, participation of platelet factors was absent.

Effect and safety of liposome-encapsulated hemoglobin neo red cells (NRCs) as a perfusate for total cardiopulmonary bypass

We developed a liposome encapsulated hemoglobin named Neo Red Cells (NRC), NRC (1) readily circulates, (2) shows a high oxygen transport efficiency, and (3) has a strong capsule membrane. In this study, we evaluated the effect of NRC as a priming solution for total cardiopulmonary bypass (TCPB) using a dog. The TCPB was started after removal of 57.1-73.3% of autologous blood and continued for 7 hours. During TCPB using NRC, the vascular resistance (VR) decreased to 1/4 of VR when red blood cells (RBC) were used. This change suggests that NRC, the viscosity of which is lower than that of RBC, reduced the load on the circulation system. The oxygen volume delivered by NRC was higher than that delivered by RBC, resulting in a greater oxygen consumption with NRC. During TCPB using NRC, the serum LDH level was lower than that using RBC. So we concluded that NRC compensated for the reduction in the oxygen transport ability, which is a disadvantage of dilution TCPB, and further increased the circulation improving effect and anti-hemolytic effect, which are advantages of the procedure. It, thus, enhanced both the safety and effectiveness of dilution TCPB.

Effect of neo red cells on hemodynamics and blood gas transport in canine hemorrhagic shock and its safety for vital organs

The purpose of this study was to evaluate the effects of liposome encapsulated hemoglobin named "Neo Red Cells (NRC)" on canine hemorrhagic shock model and its safety for the vital organs in a whole blood exchange model. HEMORRHAGIC SHOCK: Nine adult mongrel dogs were used. Under mechanical ventilation inhaling room air, blood was withdrawn via an artery at a rate of 40 ml/min in order to induce hemorrhagic shock (systolic pressure below 60 mm Hg) and then NRC was transfused. For each animal, three to five cycles of bloodletting and NRC transfusion were performed. After blood exchange, total peripheral resistance index (TPRI) decreased and cardiac index (CI) increased. These changes were more marked in the high exchange group (exchange rate over 88%; five animals) than in the low exchange group (less than 88%; four animals), indicating that the low viscosity NRC reduced the load on the circulatory system. The A-V difference in oxygen content per lg hemoglobin was greater after blood exchange, indicating that oxygen binding capacity of NRC is higher than that of red blood cells. WHOLE BLOOD EXCHANGE: Five beagles were used for the blood exchange. The blood was withdrawn from an artery at a rate of 15 ml/min and NRC was infused at the same time. A dog whose blood was exchanged with hydroxyethylstarch instead of NRC died within 15 hours after blood exchange. Three dogs whose blood was exchanged with NRC (exchange rate was from 82 to 90%) have been living over a year without any side effects. A dog sacrificed on the 15th postoperative day for autopsy, microscopically showed no side effects in vital organs. We conclude that NRC is more suitable than natural blood for treatment of hemorrhagic shock and safe for vital organs.

[Evaluation of factors aggravating and delaying recovery from postoperative hypercoagulable state in patients operated on for esophageal cancer]

When a living body is invaded to a high degree, a hypercoagulable state develops. The radical operation for esophageal cancer is known as a very high risk operation. The purpose of this study is to evaluate in detail the postoperative changes in platelet, coagulation and fibrinolytic systems, in 34 patients operated on for esophageal cancer, and to clarify the factors contributing to both the aggravation and delay of recovery from the postoperative hypercoagulable state. Operating time and blood loss during surgery were factors aggravating the postoperative hypercoagulable state. The mechanism of coagulation progressed significantly in those patients requiring 500 minutes or more operating time and having a blood loss of 600 ml or more during surgery. Age was seen as an important factor delaying recovery, as the recovery of the coagulative parameters was delayed significantly in patients aged 70 or above. Hepatic function was the most important of post operative organ functions. Renal, cardiac and respiratory functions were unrelated to the postoperative hypercoagulable state.

Oxygen transport capacity and hemodynamic effect of newly developed artificial blood "Neo Red Cells (NRC)"

The purpose of this study was to evaluate liposome-encapsulated hemoglobin, named Neo Red Cells (NRC), on hemodynamics and oxygen-transport capacity in a blood exchange experiment. The experiment was carried out in nine mongrel dogs. Depending on the percentage of blood exchange with NRC, the animals were divided into two groups; Group I (4 animals with an exchange rate less than 88%), and Group II (5 animals with an exchange rate over 88%). After blood exchange, total peripheral vascular resistance index (TPRI) decreased and cardiac index (CI) increased. These changes were more marked in Group II than in Group I, thus showing that NRC relieved the burden on the heart, probably due to the fact that the viscosity of NRC is 2 cp which is less than 1/3 that of whole blood. The oxygen binding capacity per 1g hemoglobin in NRC was 2-4 times as much as red blood cells. Thus, NRC was superior to natural red blood cells in terms of oxygen transport capacity and its effects on the circulatory system.

Study of effect of the newly developed artificial blood "Neo Red Cells (NRC)" on hemodynamics and blood gas transport in canine hemorrhagic shock

The purpose of this study is to evaluate the newly developed liposome-encapsulated hemoglobin, named Neo Red Cells (NRC), in the treatment of hemorrhagic shock. The particle size of NRC is 180 +/- 88 nm, the hemoglobin concentration is 5.6 g/dl, the viscosity is 2 cp and P50 is 49.5 mmHg. The experiment was carried out on six mongrel dogs suffering hemorrhagic shock. Blood was extracted from the femoral artery and blood pressure became lower than 60 mmHg. NRC in amount equal to the amount of blood extracted was transfused immediately. Inhalating normal room air, the above manipulation was repeated 3-5 times. After 59% to 88% blood exchange using NRC, the total peripheral vascular resistance index (TPRI) was reduced and the cardiac index (CI) was increased, thereby alleviating the burden on the heart. The reduction of TPRI in the presence of hemorrhagic shock is presumed to be due to the small size of the NRC granules and their low viscosity. As the exchange rate increased, the oxygen consumption (VO2) increased remarkably, presumably due to the increase of CI and A-V difference of oxygen content. The conclusion of the study is that NRC is more suitable than natural blood for the treatment of hemorrhagic shock.

Effect of neo red cells on the canine hemorrhagic shock model

This study evaluated the newly developed artificial red blood cells named Neo Red Cells (NRC) after hemorrhagic shock in mongrel dogs. NRC is prepared as microcapsules by a method in which stroma-free hemoglobin is encapsulated using a bimolecular lipid membrane called liposome. The particle size is 0.2 micron, methemoglobin content is less than 5% and the hemoglobin concentration is 5.6 g/dl. We analyzed blood gases and hemodynamics and carried out laboratory examinations after 59-88% blood exchange using NRC. The hemodynamic parameters returned to the normal range after NRC. Inhaling normal room air, oxygen carried by NRC was 60.40% at the exchange rate of 88%. Renal and hepatic function and other laboratory findings were normal after administration of NRC. After further study and improvement NRC could be considered suitable as artificial blood for treatment of hemorrhagic shock.

[A study of the right ventricular load at the unilateral pulmonary artery occlusion test after pneumonectomy]

After pneumonectomy, it is recognized that the absolute reduction of the pulmonary vascular bed makes the right ventricular afterload increase and can cause right heart failure in patients with low cardiopulmonary reserve. Therefore, we investigated how the right ventricular load was predicted by UPAO test, comparing hemodynamics at the time of the test with those after pneumonectomy in patients with lung cancer. At the test, the absolute reduction of the pulmonary vascular bed made the right ventricular afterload increase but the right ventricular pump function was maintained at the preoperative level by the increase of the right ventricular work load, namely, by the contraction of the right ventricle. After pneumonectomy, the absolute reduction of the vascular bed did not always make the afterload increase and in spite of the decreased preload the pump function was maintained at the preoperative level by increased heart rate. Additionally, the increase of the right ventricular work load improved during early postoperative days. It was concluded that UPAO test was apt to overestimate the right ventricular load of the postoperative day because it was done under the condition of the different compensatory function from the postoperative hypovolemic change.

[Reevaluation of the unilateral pulmonary artery occlusion test--hemodynamics after lobectomy and pneumonectomy for lung cancer]

After lobectomy, it is recognized that functional as well as absolute reduction occurs in residual lobes of the operated side. So whether lobectomy is indicated or not is determined by the same criteria as those for pneumonectomy, namely, by the unilateral pulmonary artery occlusion (UPAO) test. However, is it really appropriate to use the same criteria for both lobectomy and pneumonectomy? To answer to this question, in patients with lung cancer we compared the hemodynamics after lobectomy (13 cases) and pneumonectomy (14 cases) with that at the UPAO test. After pneumonectomy, the mean pulmonary arterial wedge pressure (mPWP) was significantly lower than that on the preoperative day and at the test. It seemed that hypovolemic change occurred in the hemodynamics after pneumonectomy. After pneumonectomy, the pulmonary arteriolar resistance index (PARI) was significantly higher than the preoperative value. It was the same as that as at the time of the UPAO test. The total pulmonary vascular resistance index (TPVRI) at the time of the test was significantly higher than the preoperative value, but the TPVRI after pneumonectomy was not significantly higher. The TPVRI tended to decrease after pneumonectomy, compared to the value predicated by the test. These results indicated that some of the cases judged inoperable on the basis of the UPAO test might be operable. On the day of lobectomy, the PARI was significantly higher than the preoperative value, but significantly lower than that at the time of the test. The cardiac index (CI) was significantly higher and the mPWP was significantly lower than each preoperative value.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of the synthetic proteinase inhibitor, FOY, on hypercoagulability after surgery for esophageal carcinoma]

Hypercoagulability develops after surgery for esophageal carcinoma, and it related closely to postoperative complications. This study evaluated the effects of the synthetic proteinase inhibitor, Cabexate Mesilate (FOY), on this hypercoagulability. The subjects used were 25 patients with a mean age of 63 who had undergone surgery for esophageal carcinoma. Of these, eight patients (test group) received FOY (2,000 mg/day) for three to 23 days after surgery, but 17 (control group) did not. In the test group, FOY controlled aggregation and release of the platelets and minimized their exhaustion. FOY almost completely checked the abnormal increase in thrombin activity which might trigger the hypercoagulability. Also, FOY suppressed the fibrinolytic activity slightly. These results indicate that FOY is effective in controlling hypercoagulability after surgery for esophageal carcinoma and in suppressing activity of the proteinases that cause both blood coagulation and fibrinolysis.

[Hypercoagulability after surgery of esophageal carcinoma]

The purpose of this study was to determine hypercoagulability in patients surgically treated for thoracic esophageal cancer. Twenty-four patients were evaluated; 19 subjected to open chest esophagectomy and 5 closed chest blunt dissection. Six patients subjected to gastrectomy served as controls. In all test patients, preoperative coagulability was within the normal range. Immediately after surgery, however, they were in a hypercoagulable state, showing a marked decrease in platelet count, prothrombin time, antithrombin III level and plasminogen level and an increase in activated partial thromboplastin time and fibrinopeptide B beta 15-42. The controls showed almost no change. There was a close correlation between hypercoagulability on one hand and the time needed for surgery and hemorrhage during 3rd to 7th postoperative day except those with multiple organ failure whose recovery was delayed and those with leakage of anastomosis whose condition did not improve even on the 10th postoperative day.

[The effect of protease inhibitors in shock]

Protease inhibitors, such as ulinastatin and gabexate mesilate, are widely used for the patients in shock state. The purpose of this study was to evaluate the effects of these protease inhibitors on renal protection and coagulofibrinolytic disorders. The obtained results were as follows: 1. Ulinastatin studies. 1) Beta 2-microglobulin (BMG) excretion and N-acetyl-beta-D-glucosaminidase (NAG) activity in urine were increased in cases of emergency operation (10 patients) compared with elective operation (38 patients). 2) In canine experimental model of renal ischemia, ulinastatin significantly improved urine volume and urine NAG levels. 3) Administration of ulinastatin suppressed urine NAG level in 12 patients, but BMG level did not significantly change. 2. Gabexate mesilate (FOY) studies. 1) All patients in shock state showed coagulofibrinolytic disorders. Especially remarkable hypercoagulability was observed in 21 patients. 2) FOY suppressed platelet aggregation and the release of beta-thromboglobulin and platelet factor 4. 3) In 24 patients, administration of FOY markedly increased the antithrombin III levels in early postoperative period. 4) Fibrinolytic system was not affected any significant changes with administration of FOY.

CONCLUSION

Our results suggested that protease inhibitors are useful for management of the patients in shock state.

[Transfer of cefmenoxime to lung tissue and thoracic muscle in thoracic surgery]

Twenty patients who were performed pulmonary resection for the disease of the lung were administered 2 g of cefmenoxime (CMX) intravenously during the operation. The CMX levels in serum, lung tissue and thoracic muscle were measured by agar-well technique. The CMX levels in lung tissue and thoracic muscle were higher than the MIC80 of CMX for Klebsiella pneumoniae, Haemophilus influenzae and Streptococcus pneumoniae which were commonly as isolated causative organisms from the patients with pulmonary infection. These results indicate that CMX will be useful agent for the prevention and treatment of pulmonary infection.