Biomedical subjects

T Masai

Publications and source records attributed to T Masai.

43 records · Page 3Linked to original sources

PubMedDate not supplied

Comparison between pulsatile and nonpulsatile circulatory assist for the recovery of shock liver.

In patients with prior shock and liver injury, mechanical circulatory assist still has a high risk of hepatic failure. The purpose of this study was to evaluate the effect of mechanical circulation using pulsatile or nonpulsatile blood pumps on shock organs, particularly shock liver. In 14 dogs, a shock liver model was produced by clamping the descending aorta above the diaphragm. After 60 minutes of ischemia, left atrial-femoral artery bypass (LHB) was started while the clamp remained in place. A pneumatic pulsatile pump (Toyobo; Tokyo, Japan) was used in seven dogs (Gr-PP) and a centrifugal pump (Biomedicus; Minneapolis, MN) in seven (Gr-NPP). In both groups the mean arterial pressure was maintained at 80 mmHg. The mean bypass flow was 96 +/- 14 ml/kg/min for Gr-PP, and 95 +/- 35 ml/kg/min for Gr-NPP. In both groups the bile flow and arterial ketone body ratio decreased significantly after ischemia, and recovered to normal after 120 min of LHB. There was no significant difference between the two groups in this model. The other parameters (glutamic oxaloacetic transaminase [GOT], glutamic pyruvic transaminase, lactate dehydrogenase, mitochondrial GOT) were independent of the period of ischemia and reperfusion, and there was no difference between the two groups. In conclusion, these results suggest that nonpulsatile circulatory assist may not be disadvantageous for the circulatory support and recovery of liver function in the setting of shock liver.

Animals↗

PubMedDate not supplied

Evaluation of a physiologic pulsatile pump system for neonate-infant cardiopulmonary bypass support.

An alternate physiologic pulsatile pump (PPP) system was designed and evaluated to produce sufficient pulsatility during neonate-infant open heart surgery. This hydraulically driven pump system has a unique "dual" pumping chamber mechanism. The first chamber is placed between the venous reservoir and oxygenator and the second chamber between the oxygenator and patient. Each chamber has two unidirectional tricuspid valves. Stroke volume (0.2-10 ml), upstroke rise time (10-350 msec), and pump rate (2-250 beats per minute [bpm]) can be adjusted independently to produce adequate pulsatility. This system has been tested in 3-kg piglets (n = 6), with a pump flow of 150 ml/kg/min, a pump rate of 150 bpm, and a pump ejection time of 110 msec. After initiation of cardiopulmonary bypass (CPB), all animals were subjected to 25 minutes of hypothermia to reduce the rectal temperatures to 18 degrees C, 60 minutes of deep hypothermic circulatory arrest (DHCA), then 10 minutes of cold perfusion with a full pump flow, and 40 minutes of rewarming. During CPB, mean arterial pressures were kept at less than 50 mm Hg. Mean extracorporeal circuit pressure (ECCP), the pressure drop of a 10 French aortic cannula, and the pulse pressure were 67+/-9, 21+/-6, and 16+/-2 mm Hg, respectively. All values are represented as mean+/-SD. No regurgitation or abnormal hemolysis has been detected during these experiments. The oxygenator had no damping effect on the quality of the pulsatility because of the dual chamber pumping mechanism. The ECCP was also significantly lower than any other known pulsatile system. We conclude that this system, with a 10 French aortic cannula and arterial filter, produces adequate pulsatility in 3 kg piglets.

Animals↗

PubMedDate not supplied

Pulsatile and nonpulsatile flows can be quantified in terms of energy equivalent pressure during cardiopulmonary bypass for direct comparisons.

The purpose of this study was to quantify and compare pulsatile and nonpulsatile pressure and flow waveforms in terms of energy equivalent pressure (EEP) during cardiopulmonary bypass in a neonatal piglet model. EEP is the ratio of the area under the hemodynamic power curve and the flow curve. Piglets, mean weight of 3 kg, were used in physiologic pulsatile pump (n = 7), pulsatile roller pump (n = 6), and nonpulsatile roller pump (n = 7) groups. Data (waveforms of the femoral artery pressure, pump flow, and preaortic cannula extracorporeal circuit pressure) were collected during normothermic cardiopulmonary bypass at 35 degrees C (15 minutes on-pump), before deep hypothermic circulatory arrest (pre-DHCA) at 18 degrees C, and after cold reperfusion and rewarming (post-DHCA) at 36 degrees C. The pump flow rate was 150 ml/kg/min in all three groups. During pulsatile perfusion, the pump rate was 150 bpm in both pulsatile groups. Although there was no difference in mean pressures in all groups, EEP and the percentage increase of pressure (from mean pressure to EEP) of mean arterial pressure and preaortic cannula extracorporeal circuit pressure were higher with pulsatile perfusion compared with nonpulsatile perfusion (p < 0.001). In particular, the physiologic pulsatile pump group produced significantly higher hemodynamic energy compared with the other groups (p < 0.001). These results suggest that pulsatile and nonpulsatile flows can be quantified in terms of EEP for direct comparisons, and pulsatile flow generates higher energy, which may be beneficial for vital organ perfusion during cardiopulmonary bypass.

Animals↗

PubMedDate not supplied

Gastric intramucosal pH during lower body circulatory arrest under open distal anastomosis with selective cerebral perfusion in aortic arch repair.

Selective cerebral perfusion (SCP) and open distal anastomosis (OD) with hypothermia has been used as a popular means for circulatory assistance in aortic arch surgery. Although SCP has become accepted for brain protection, the influence of OD accompanying circulatory arrest on lower body ischemia is not known. We studied gastric tonometry (gastric intramucosal pH [pHi]) to estimate splanchnic ischemia during OD, and its relationship to postoperative organ function. In five patients (pts) (range, 65-78 years; mean, 71 years; group OD) who underwent arch replacement using SCP and OD with moderate hypothermia (25 degrees C) during the period from March to August of 1999, pHi was measured precardiopulmonary bypass (pre-CPB), 30 min of CPB (CPB30), 10 min after OD (OD10), at end of CPB, and post-CPB. Eight pts (range, 52-78 years; mean; 66 years) who underwent standard CPB (33 degrees C) during the same period (coronary artery bypass surgery in six and valve surgery in two) served as controls (group C). In group OD, pHi was significantly decreased at OD10 (7.35 +/- 0.03 at CPB30 vs. 7.23 +/- 0.07 at OD10, p < 0.05) but recovered by the end of CPB (7.32 +/- 0.02). Creatinine clearance on the first postoperative day (1POD) was significantly (p < 0.05) lower in group OD (82 +/- 40 ml/min) than in group C (126 +/- 25 ml/min), although there was no significant difference in preoperative values between the two groups. The pHi at OD10 did not correlate with the duration of OD (range, 30-47 min; mean, 38 min), whereas pHi at OD10 significantly correlated with BUN (r = -0.973, p = 0.0054), Cr(r = -0.977, p = 0.0043), and CCr (r = 0.908, p = 0.0328) on 1POD. One patient in group OD developed paraplegia and renal failure postoperatively. His pHi at OD10 was severely decreased to 7.11. These results suggest that intraoperative monitoring of pHi may be useful for the evaluation of visceral organ ischemia during OD in arch replacement and may contribute to improved technique for circulatory assistance in aortic surgery.

Aged↗

PubMedDate not supplied

Usefulness of the low profile "True 8" intra-aortic balloon pumping catheter for preventing limb lschemia.

The most important limitation in the use of an intra-aortic balloon pumping (IABP) is the risk of vascular complications. Recently, an IABP catheter with an 8.0 French shaft and low profile that may decrease the risk of vascular morbidity has been developed. We evaluated the in vitro balloon performance and the prevention of limb ischemia in clinical use. An 8.0 French IABP catheter was compared with a standard 9.5 French catheter. Inflation time (IT), deflation time (DT), and changes in volume (V) generated by the balloon were measured during the pumping cycle in an experimental model. The inflation velocity (V/IT) and deflation velocity (V/DT) were calculated as parameters of balloon performance. At 120 bpm the V/IT and V/DT were 0.34 ml/msec and 0.28 ml/msec with the 8.0 French, and 0.33 ml/msec and 0.24 ml/msec with the 9.5 French catheter. Twelve patients with coronary artery disease, ranging in age from 41 to 87 years (mean, 66 years), who underwent IABP support, were divided into group 1 (8.0 French, n = 4) and group 2 (9.5 French, n = 8). Ankle-arm pressure index (API), lactate extraction ratio (LER) in the limb with IABP insertion, and cardiac index (CI) were measured at 1, 12, and 24 hours postoperatively. There were no major vascular complications and no counterpulsation related morbidity. There was no significant difference between the two groups with regard to age, duration of IABP support, and incidence of peripheral vascular disease and diabetes. The percentage of women patients was significantly higher in group 1 (100% vs. 25%), whereas body surface area was significantly smaller (1.45 +/- 0.14 vs. 1.68 +/- 0.12 m2). The API in group 1 were slightly higher than those in group 2 throughout the observed period (not significant). The LER and Cl showed no significant differences between the two groups. These results suggest that the 8.0 French IABP catheter with a low profile has an acceptable in vitro performance, and its clinical application may be effective in preventing limb ischemia in a high-risk subset of patients such as women and smaller patients.

Adult↗

PubMedDate not supplied

Portable cardiopulmonary support system as a bridge to left ventricular assist system implantation. A new strategy for the treatment of end stage cardiac disease.

The key to the successful implantation of a left ventricular assist system (LVAS) for patients with end stage cardiac disease is whether the functions of other vital organs are irreversibly damaged or not. The portable cardiopulmonary support system (PCPS) is not only as convenient as, but is more powerful than, the intra-aortic balloon pump (IABP) in resuscitating impaired end organ function. To investigate the efficacy of PCPS in end stage cardiac disease, end organ function before and after the application of PCPS was retrospectively analyzed for end stage cardiac disease. From 1992 to 1996, five cardiomyopathy patients with deterioration in end organ function, despite application of IABP, underwent PCPS support before implantation of LVAS. Urine volume and levels of liver enzymes (sAST and sALT) and serum creatinine were determined before and after institution of PCPS. After the start of PCPS, the urine output increased significantly (1,840 +/- 450-4,340 +/- 470 ml/day, p < 0.01), and levels of sAST, sALT, and serum creatinine decreased significantly (630 +/- 220-150 +/- 50 IU/L, 630 +/- 260-260 +/- 130 IU/L, and 2.9 +/- 0.5-1.2 +/- 0.1 mg/dl, respectively; p < 0.05). All five patients were successfully bridged to LVAS implantation, and none died of multiple organ failure caused by pre-existing cardiac failure. These results indicate that PCPS before LVAS implantation is useful in resuscitating impaired end organ function and improving the survival rate with LVAS implantation for end stage cardiac disease.

Adult↗

PubMedDate not supplied

Hepatic sinusoid endothelial dysfunction plays a role in hyperbilirubinemia in patients following implantation of an LVAD.

To clarify the mechanism of hyperbilirubinemia in the setting of a left ventricular assist device (LVAD), the change in hepatocellular function, hepatic sinusoid endothelial microcirculation, and inflammatory response before and after LVAD implantation were evaluated. Eight consecutive patients underwent the placement of an LVAD, and serum levels of total bilirubin (TB), transaminases [alanine transaminase (ALT), aspartate transaminase (AST)], interleukin (IL-6, IL-8), and hyaluronic acid (HA), an indicator of hepatic sinusoidal circulation, were measured before and after LVAD implantation. The TB of all patients increased significantly in the first post operative week (p < 0.05 vs. pre-operatively). In five patients, the elevated TB (4.6 +/- 4.1 mg/dl) returned to pre-operative levels (2.7 +/- 2.0 mg/dl) by the 14th post operative day (Group R), but in the other three patients who died of multiple organ failure, the level of TB increased to 39.9 +/- 16.4 mg/dl (Group A). Levels of HA and IL-8 had good correlation with the level of TB (HA: r = 0.60, p < 0.05; IL-8: r = 0.55, p < 0.05). However, AST, ALT, and IL-6 were not related to changes in TB. These results suggest that hepatic sinusoid endothelial dysfunction and inflammatory reaction may play a significant role in hepatic failure in patients following implantation of an LVAD.

Adult↗