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.

[Localized right atrial tamponade after aortic valve replacement].

A 78-year-old man developed isolated right atrial tamponade 15 hours following aortic valve replacement. There were excessive postsurgical bleeding, low blood pressure, and low cardiac output. Volume expansion and inotropic therapy did not increase blood pressure. There were no cardiomegaly and echo-free space. Diagnosis was made by appearance of pulsus paradoxus and transthoracic echocardiography and confirmed by surgery. The clinical picture was improved dramatically after surgical removal of the hematoma. Right atrial tamponade leads to a unique clinical conglomeration of hemodynamic and echocardiographic features. Constant attention to this entity is necessary to make a timely diagnosis.

[A newly designed parallel connecting tube makes feasible high speed blood transfusion with a transfusion pump].

Use of a transfusion pump (BP 101, Terumo, Tokyo) makes it feasible to obtain a stable and almost constant ejection volume at a flow rate of 99 ml.min-1, with no untoward effects of the intravenously placed needle and the microfilter located in the circuit. An air sensor ensures that the pump will cease operation immediately and automatically if an air bubble occurrs in the circuit. When a blood bag is conventionally connected to a connecting tube, at the maximum flow rate, one must set up a new blood bag within a few minutes, and in emergency situations with a shortage of hands, this would be unduly troublesome. When 5-7 blood bags (400 ml) is connected to 5-7 parallel connecting tubes, the pump will continuously eject blood approximately to 2000 ml at 99 ml.min-1, without replacing the blood bags.

[Recurrent transient increases in liver enzymes specifically after isoflurane anesthesia].

A 69 y-old female underwent orthopedic surgery 12 times in our hospital. A variety of agents were used for anesthesia. She developed episodes of transient increase in liver enzymes only after each of three isoflurane anesthesia (GOT : 311, 292, 328 IU.l-1, GPT: 341, 264, 274 IU.l-1). We suspected drug-induced liver dysfunction, but results of a lymphocyte stimulation test were negative. We conclude that her liver dysfunction was not severe enough to cause clinical symptoms. In such susceptible patients we should be careful of our choice of anesthetic drugs.

[Sudden onset of bronchospasm and persistent hypotension during spinal anesthesia in a patient on long-term psychotropic therapy].

We experienced perioperative management of a patient on long-term psychotropic therapy. The patient was a 65-year-old man who underwent TUR of the prostate under spinal anesthesia. Bronchospasm and persistent hypotension occurred immediately after the beginning of TUR. Aminophylline improved bronchospasm, but it was difficult to keep blood pressure with continuous infusion of norepinephrine or epinephrine. The patient recovered from anesthesia safely. We should pay attention to bronchospasm as well as hypotension in a patient on long-term psychotropic therapy during perioperative period.

[Appropriate duration of postoperative pain relief by continuous epidural infusion in patients receiving hysterectomy or ovarian tumor resection: comparison of three methods].

We evaluated effects of continuous epidural infusion on postoperative pain, and frequency of its side effects. Patients who had undergone elective gynecological operations were randomly allocated into three groups by difference in duration of indwelling of epidural catheters: patients receiving epidural block only during operations (group M); patients receiving continuous epidural infusion for 2 postoperative days (group B 2); patients receiving continuous epidural infusion for 4 postoperative days (group B 4). In group M, morphine 3 mg and 1 or 2% lidocaine 5-7 ml were given before the start of operation, and epidural catheter was removed after the end of operations. In group B 2 and B 4, morphine 2 mg and 1 or 2% lidocaine 5-7 ml were given before the start of operation, and morphine 8 mg in 50 ml of 0.25% bupivacaine was continuously infused at a rate of 0.5-1 ml.hr-1. We evaluated visual analogue scale (VAS) at rest and moving, and verbal descriptor pain score. Frequencies of supplementary analgesics, vomiting and nausea, residual urine volume after removal of bladder catheter, and timing to initiation of bowel movement after operation were also recorded. VAS at rest was significantly higher in group M than in groups B 2 and B 4 for 2 postoperative days, but no significant difference was seen between the three groups for three postoperative days. VAS at moving did not differ between the 3 groups. Verbal descriptor pain score was significantly higher in group M than in groups B 2 and B 4 for 3 postoperative days, but it was not different between groups B 2 and B 4. In group B 2, patients complained increased abdominal pain after removing catheters. Frequencies of supplementary analgesics were 3.7, 0.6 and 0.4 times in group M, B 2, B 4, respectively. Times to initiation of bowel movement after operation were 39.8, 46.5 and 61.7 hrs in group M, B 2, and B 4, respectively, and most patients in group B 4 felt uncomfortable. These results suggest that continuous epidural analgesia for 2 postoperative days is appropriate, but the duration should be determined according to patient's conditions and complications.

[A patient with severe ventricular tachycardia who was saved by prolonged extracorporeal lung and heart assist].

A 47-y-o man had been suffering from cardiac failure due to refractory ventricular tachycardia (VT) after myocardial infarction. He underwent resection of the left ventricular aneurysm and cryocoagulation of the arrhythmogenic foci. On the 2nd post-operative day, VT often recurred in spite of repeated cardioversion and drug therapy, and threatened his life, even under IABP. Therefore, a veno-arterial bypass route was made and extracorporeal lung and heart assist, ECLHA, was started with a heparin bonded Maxima lung on the following day. Even under ECLHA, VT continued to recur. Cryocoagulation of the VT foci was tried again, without immediate success. A record high dose of beta-blockers, given under the circulatory support by ECLHA, stopped VT on the following day. The patient was weaned from the ECLHA circuit 12 days after the first operation, then from IABP on the 14th day. During the 10 day course of surgeries and ECLHA, the patient had almost 100 defibrillations. But for ECLHA, we may say that the patient couldn't have survived two open heart surgeries, administration of a great amount of beta-blockers, and repeated cardiac arrest without neurological sequelae.

Cytokine generation in rabbits during extracorporeal lung assist with a mini hollow fiber lung.

To examine host responses to extracorporeal lung assist (ECLA) in small animals, we developed a mini hollow fiber lung of nonmicroporous polyolefin and an extracorporeal bypass circuit with a priming volume of 25 ml. This circuit allowed ECLA of up to 72 h without blood transfusion in 20 rabbits. The ECLA procedure induced the appearance of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) receptor antagonist (IL-1Ra) in plasma, but not IL-1 beta. However, these changes were observed only at the initial stage of ECLA, and the levels returned to pre-ECLA levels within 24 h. Although leukocytes adhering to the hollow fibers were immunohisto-chemically positive for IL-1 beta and IL-Ra, the plasma levels of these cytokines in response to ECLA were not different from those observed in rabbits given anesthesia and subjected to minor surgery but without ECLA. Thus, ECLA itself is a minor factor in the production of these cytokines.

Experimental evaluation of the V-point heparin-bonding system applied to a dense-membrane artificial lung during 24-hour extracorporeal circulation in beagles.

Heparin was covalently bonded to a hollow-fiber dense-membrane artificial lung and circuit using a silane coupling agent and polyethyleneimine as a spacer. This study investigated whether the novel artificial lung could sustain prolonged extracorporeal lung assist (ECLA) by venoarterial bypass in beagles using minimal anticoagulants. We maintained ECLA for 24 h in 3 groups of minimal systemic heparinization, heparinization with the new anticoagulant nafamostat mesilate, and without any systemic anticoagulant. The results were assessed from the functional performance of the artificial lung and by macroscopic and microscopic examination after the experiments. Artificial lung function, hemodynamics, hemogram, and platelet aggregation activity were well maintained in all groups. There was no plasma leakage from the artificial lung. Although several clots were observed in stagnant areas of the artificial lungs and circuits, there was no clot formation inside the artificial lung in any group. This highly biocompatible, heparin-bonded dense-membrane artificial lung performed well and safely during prolonged ECLA with blood clotting times less than 120 s.