Masafumi Tashiro

Delayed platelet dysfunction in prolonged induced canine hypothermia

UNLABELLED Mild to moderate hypothermia (33-32 degrees C) is recognized as beneficial for brain protection after brain trauma. However, there are few experimental reports on hemostatic changes during prolonged hypothermia. We compared hemostatic changes during 72 h of mild to moderate hypothermia with data in normothermic dogs. METHOD Mongolian dogs in a hypothermic group (N=7, 33 degrees C core temperature) and normothermic group (N=6, 37.5 degrees C core temperature) were anesthetized and instrumented to control temperatures and record hemodynamic changes continuously. Hypothermia or normothermia was maintained for 72 h. Platelet count, platelet aggregation, and thromboelastograms (TEG) were measured in each group. RESULTS Heart rate, blood pressure, pulmonary pressure and blood gas were not significantly different between the two groups. Platelet counts, compared to baseline values, were significantly decreased in both groups (P<0.01). Platelet aggregation was significantly decreased in the hypothermic group after 24 h (P<0.04). CONCLUSION Long-term hypothermia induced platelet dysfunction, leading to decreased platelet aggregation and prolonged coagulation time (R and K times of TEG).

Preliminary experiment with a newly developed double balloon, double lumen catheter for extracorporeal life support vascular access.

Recently, venovenous extracorporeal life support (VVECLS) using a double lumen catheter has been clinically used to avoid neurologic complications in the treatment of respiratory failure for neonates. However, recirculation, which is a limiting factor for oxygen delivery, still exists, and thus it does not contribute to oxygenation of the patient. We developed a newly designed double lumen catheter with a double balloon (DBDL) catheter for ECLS vascular access and performed two animal preliminary experiments in normal and hypoxic dog models (normal ventilation and one lung ventilation experiments) to investigate whether the DBDL catheter could prevent recirculation and maintain oxygen delivery to systemic circulation. The DBDL catheter (JCT Co., Hiroshima, Japan) of 15 Fr was fabricated from silicone. It consists of two lumens for drainage and return of blood with two balloons (distal and proximal balloons) that prevent oxygenated blood mixing with unoxygenated blood. VVECLS using a DBDL catheter was performed in 13 mongrel dogs (8 dogs for normal ventilation experiment weighing 12.9 ± 1.6 kg [mean ± SD], 5 dogs for one lung ventilation experiment weighing 16.6 ± 2.5 kg [mean ± SD]) under anesthesia in the two experiments. The bypass flow ranged from 10–40 ml/kg per minute in the normal ventilation experiment. VVECLS in the one lung ventilation experiment was performed with maximal bypass flow for 6 hours (ranged from 25.2 ± 8.0–28.3 ± 8.7 ml/kg per minute at balloon inflation and deflation). Recirculation and oxygen transfer of artificial lung with or without balloon inflation during VVECLS were studied. Recirculation decreased with balloon inflation at varied bypass flows during VVECLS in the normal ventilation experiment (varied from 1.5 ± 14.6–12.8 ± 16.7%) and for 6 hours after VVECLS initiation in the one lung ventilation experiment (varied from 12.2 ± 12.2–19.2 ± 6.5 %). In particular, the values at 3 and 6 hours were significantly lower than that of balloon deflation in the one lung ventilation experiment. The difference in O2 content between inlet and outlet in the artificial lung with balloon inflation was significantly higher than that of balloon deflation (varied from 3.7 ± 1.8–4.8 ± 1.9 ml/dl, p < 0.05) at the bypass flow of 10–30 ml/kg per minute in the normal ventilation experiment and at 5 hours after VVECLS initiation in the one lung ventilation experiment (varied from 10.6 ± 1.6–11.7 ± 1.8 ml/dl). The blood gas analysis of systemic circulation with balloon inflation revealed that the values of PaO2 (varied from 83.8 ± 11.4–96.9 ± 23.4 mm Hg) and PaCO2 (37.7 ± 9.2–40.4 ± 11.8 mm Hg) were higher and lower, respectively, compared with balloon deflation. In particular, PaO2 level was significantly higher than that of the preECLS value at the bypass flow of 20–40 ml/kg per minute (varied from 83.8 ± 11.4–96.9 ± 23.4 mm Hg, p < 0.05). In the one lung ventilation experiment, systemic PaO2 and PaCO2 levels at balloon inflation were higher and lower, respectively, compared with balloon deflation during VVECLS for 6 hours. At balloon inflation, the value of PaO2 at 6 hours after VVECLS initiation was significantly higher than that at balloon deflation. A newly designed DBDL catheter for ECLS vascular access successfully reduced recirculation and maintained oxygen delivery to systemic circulation during VVECLS. These results suggest that a high bypass flow may not be necessarily required in terms of oxygen delivery to systemic circulation when the DBDL catheter was used as an ECLS vascular access.

Heparin bonding of the extracorporeal circuit reduces thrombosis during prolonged lung assist in goats.

This study investigated whether an artificial membrane lung of nonmicroporous polyolefin hollow fibers bonded with heparin could prolong venoarterial extracorporeal lung assist (ECLA) with low dose systemic heparin in goats. We compared heparin bonded circuits (Carmeda Bioactive Surface, “HB” group, n = 5) with non heparin bonded circuits (“NHB” group, n = 5) in venoarterial ECLA (V-A ECLA) for 7 days. Activated coagulation time (ACT) was maintained at approximately 130 sec by systemic infusion of small doses of heparin in the HB group, and at 200–230 sec in the NHB group. Thrombus formation was assessed by visual examination of the circuit, and possible cerebral embolization of thrombi was observed from behavioral abnormalities of the animals. The mean heparin dose given during ECLA was 20.4 ± 3.6 U/kg per hr in HB, and 50.9 ± 14.2 U/kg per hr in NHB, significantly less in HB than NHB (p < 0.01). Blood gas changes across the oxygenator, bypass flow rate, platelet aggregation activity, platelet counts, fibrin monomer (FM) test, and antithrombin-III (AT-III) activity did not differ between the two groups. In HB, thrombi were fewer and no abnormal neurologic symptoms were observed during ECLA. Numerous thrombi were observed in all oxygenators with NHB. One NHB goat developed convulsions and cerebral hemorrhage on the 6th day of ECLA. Nonmicroporous polyolefin hollow fibers can be bonded with heparin. An artificial membrane lung constructed of these fibers showed good anticoagulation by decreased thrombus formation with a small dose of infused heparin.

Does veno-arterial bypass without an artificial lung improve the outcome in dogs undergoing cardiac arrest?

We hypothesized that maintaining circulation and blood pressure by veno-arterial bypass (V-A bypass) without oxygenation would improve cardiopulmonary resuscitation (CPR) and survival rates. A total of 32 dogs, divided into four groups, were subjected to normothermic ventricular fibrillation (VF) for 15 min. The method of CPR was the same in the four groups, except for the method and timing of V-A bypass. We attempted to resuscitate the dogs without V-A bypass (control), with V-A bypass not including an artificial lung during VF, with V-A bypass not including an artificial lung during CPR, and with V-A bypass including an artificial lung during CPR. CPR was continued until restoration of spontaneous circulation (ROSC) or for 30 min. Although blood pressure was well maintained, severe hypoxemia was observed during V-A bypass without an artificial lung. The resultant hypoxemia was very detrimental. ROSC was achieved more easily in all dogs in the bypass group with an artificial lung. No significant difference in survival rates was demonstrated among the four groups (P = 0.11). We concluded that V-A bypass without oxygenation does not improve the chances for CPR and outcome after cardiac arrest in dogs. Our results suggest that oxygenation is indispensable in CPR.

Total and prolonged filling of the lungs with Ringer’s solution under extracorporeal lung assist (ECLA) in dogs

Background: Massive alveolar lavage has been used clinically to remove materials accumulated in the alveoli. Recently, filling the lungs with oxygenated perfluorochemical (total liquid ventilation) has been investigated. However, effects of complete and prolonged filling of bilateral lungs with aqueous fluid, such as saline or Ringer’s solution, has not been evaluated, although it is possible to sustain gas exchange without the natural lung by using extracorporeal circulation and an artificial lung (extracorporeal lung assist: ECLA). It is also not known whether the lung can recover gas exchange ability after prolonged fluid filling.

Attenuation of the vagolytic effect of atropine during high thoracic epidural anesthesia by heart rate fluctuation analysis

Fifteen surgical patients received an epidural injection of 12 ml of 1.5% lidocaine through a catheter placed at C7-T1, followed by further injection as required. An intravenous bolus of 0.5 mg of atropine sulfate was administered simultaneously with the initial epidural injection. The high-(HFC: 0.15–0.4 Hz) and low-frequency components (LFC: 0.05–0.15 Hz) of the power spectrum of heart rate fluctuation, and the LFC/HFC ratio were calculated. At 30 min after the initial lidocaine and atropine injection, the HFC decreased to 21% of the baseline value and the LFC decreased to 11%. At 90 min, the HFC showed gradual recovery to 69% whereas the LFC remained low (22%). These results indicate that 0.5 mg of intravenous atropine reduces the autonomic imbalance that occurs under high thoracic epidural anesthesia, but its duration is too short to be effective throughout the course of anesthesia.

Three cases of reflex sympathetic dystrophy in the lower extremity treated with lumbar sympathetic ganglion block

Case 1: A man of sixteen years, weighing 60 kg, had a light traffic accident merely causing his left knee to be sprained. Since then, he had suffered from a continuous pain of the left knee. The arthroscopy of the left knee joint, performed approximately one month after the accident under subarachnoidal block using 0.3% dibucaine, showed no significant pathogenesis of the pain. Following this arthroscopic examination, the pain gradually spread over his left leg from the knee. On his first visit to our clinic about five months after the traffic accident, the following findings were observed in the left leg: a sustained, intractable and burning pain; hyperesthesia in the inner side of the calf; hyperpathia with a trigger zone in the