[Perioperative ß-adrenergic blocking agents and postoperative prognosis].

Perioperative myocardial ischemia occurs frequently within 48 hrs postoperatively, with few characteristic symptoms and its prognosis is known to be poor. Anesthesiologists should carefully monitor these patients with high risk factors for cardiac events until the 2nd postoperative day. Medical treatment should be initiated promptly according to the cause of perioperative increase in sympathetic nervous activity. At present, it is not clear whether beta-adrenergic blocking agents can improve long-term prognosis for patients undergoing noncardiac surgery. However, it is prudent to continue the medication in patients who are given beta-adrenergic blocking agents preoperatively, and to resume the drug postoperatively as soon as possible. Moreover, since elderly patients are prone to suffer from cerebral infarction, sufficient attention should also be paid to changes in blood pressure.

Vascular perfusion limits mesenteric lymph flow during anaphylactic hypotension in rats.

To determine fluid extravasation in the splanchnic vascular bed during anaphylactic hypotension, the mesenteric lymph flow (Q(lym)) was measured in anesthetized rats sensitized with ovalbumin, along with the systemic arterial pressure (P(sa)) and portal venous pressure (P(pv)). When the antigen was injected into the sensitized rats (n = 10), P(sa) decreased from 125 ± 4 to 37 ± 2 mmHg at 10 min with a gradual recovery, whereas P(pv) increased by 16 mmHg at 2 min and returned to the baseline at 10 min. Q(lym) increased 3.3-fold from the baseline of 0.023 ± 0.002 g/min to the peak levels of 0.075 ± 0.009 g/min at 2 min and returned to the baseline within 12 min. The lymph protein concentrations increased after antigen, a finding indicating increased vascular permeability. To determine the role of the P(pv) increase in the antigen-induced increase in Q(lym), P(pv) of the nonsensitized rats (n = 10) was mechanically elevated in a manner similar to that of the sensitized rats by compressing the portal vein near the hepatic hilus. Unexpectedly, P(pv) elevation alone produced a similar increase in Q(lym), with the peak comparable to that of the sensitized rats. This finding aroused a question why the antigen-induced increase in Q(lym) was limited despite the presence of increased vascular permeability. Thus the changes in splanchnic vascular surface area were assessed by measuring the mesenteric arterial flow. The mesenteric arterial flow was decreased much more in the sensitized rats (75%; n = 5) than the nonsensitized P(pv) elevated rats (50%; n = 5). In conclusion, mesenteric lymph flow increases transiently after antigen presumably due to increased capillary pressure of the splanchnic vascular bed via downstream P(pv) elevation and perfusion and increased vascular permeability in anesthetized rats. However, this increased extravasation is subsequently limited by decreases in vascular surface area and filtration pressure.

Assessment of peripheral arterial disease of lower limbs with ultrasonography and ankle brachial index at the initiation of hemodialysis.

AIM: Peripheral arterial disease (PAD) of the lower limbs carries high risks of leg amputation, quality of life deterioration, and death in hemodialysis (HD) patients. However, the frequency of PAD at the initiation of HD has not been adequately documented. In addition, the applicability of ultrasonography to diagnosing PAD is not yet clear in HD patients. METHODS: Twenty-seven patients within three months after HD initiation were enrolled. Ultrasonography was performed regardless of ischemic symptoms. Significant stenosis or obstruction of lower limb arteries on ultrasonography was diagnosed as PAD. RESULTS: Sixteen of the 27 (59.3%) showed PAD on echography. On the other hand, only six of the 27 (22.2%) had an ABI < 0.9. Sixteen patients had a total of 37 lesions revealed by ultrasonography, and the average number of PAD lesions was 2.3 per patient. The numbers of PAD lesions on ultrasonography were as follows: iliac artery, 7; femoral-popliteal artery, 15; and infra-popliteal artery, 15. The ABI was 0.95 +/- 0.29 in PAD and 1.23 +/- 0.13 in non-PAD patients (p = 0.005). CONCLUSIONS: A high prevalence of PAD at HD initiation was demonstrated. PAD may be missed using only the ABI (ankle brachial index). Ultrasonography is a reliable and non-invasive examination for detecting PAD.