Sympathetic tone restrains arterial distensibility of healthy and atherosclerotic subjects.

BACKGROUND: Sympathetic activation induced by cold pressor test or cigarette smoking is accompanied by a marked reduction of radial artery distensibility. It is not known, however, whether arterial distensibility is under tonic sympathetic restraint, or whether this restraint involves arteries greater than the radial one in both normal and pathological conditions. METHODS: We studied the distensibility of radial artery by continuous ultrasonographic assessment of the changes in arterial diameter over the diasto-systolic pressure range (finger pressure measurement) in eight patients with a Dupuytren disease before and 20 min after ipsilateral brachial plexus anaesthesia. We also studied ultrasonographic distensibility of femoral artery in seven subjects before and 20 min after ipsilateral subarachnoid anaesthesia, performed before arthroscopic surgery, and in five patients with claudicatio intermittens before and 1 month after ipsilateral removal of the lumbar sympathectomy chain. In all three conditions, the contralateral artery served as control. RESULTS: The three interventions did not cause any significant alteration in blood pressure and heart rate. Radial artery distensibility was markedly increased by ipsilateral anaesthesia of the brachial plexus (+36%, P<0.01). This was the case also for femoral artery distensibility both following ipsilateral subarachnoid anaesthesia in healthy subjects (+47%, P<0.05) or ipsilateral sympathetic gangliectomy in patients with peripheral artery disease (+26%, P<0.05). In all three instances, the distensibility of the contralateral artery remained unaffected. CONCLUSIONS: These data indicate that the sympathetic nervous system exerts a marked tonic restraint of arterial distensibility. This restraint involves medium-size and large muscular arteries and can also be seen in subjects with peripheral artery disease. This stiffening influence may increase the traumatic effect of intravascular pressure on the vessel wall and favour atherosclerosis.

Pre- and postoperative intra-articular analgesia for arthroscopic surgery of the knee and arthroscopy-assisted anterior cruciate ligament reconstruction. A double-blind randomized, prospective study.

We tested the effectiveness of different intra-articular analgesics and of pre-emptive intra-articular analgesia for arthroscopy-assisted anterior cruciate ligament reconstruction (ACLR) and for operative knee arthroscopy. Eighty-two patients underwent operative knee arthroscopy under selective subarachnoid anaesthesia (group A), and 60 patients underwent arthroscopy-assisted ACLR under general anaesthesia (group B). Patients were randomly assigned to intra-articular analgesic treatment as follows. Group A: 1, morphine 2 mg; 2, preoperative morphine 2 mg; 3, morphine 5 mg; 4, preoperative morphine 5 mg; 5, bupivacaine 0.25% 20 ml; 6, bupivacaine 0.25% 20 ml + morphine 2 mg; 7, saline solution 20 ml. Group B: 1, morphine 2 mg; 2, morphine 5 mg; 3, preoperative morphine 5 mg; 4, bupivacaine 0.25% 20 ml; 5, bupivacaine 0.25% 20 ml + morphine 2 mg; 6, saline solution 20 ml. All opioids were diluted in 20 ml of saline solution. After postoperative administration the tourniquet was left in place for 10 min. After preoperative administration the intra-articular surgical procedure was delayed for about 5-10 min. In the postoperative period we recorded: total consumption of ketoprofen given i.v. on demand as rescue analgesic treatment; pain scores before surgery and at 1st, 3rd, 6th, 12th and 24th h; occurrence of local anaesthetic or opioid side-effects. Group A (operative knee arthroscopy): all morphine groups (A1, A2, A3, A4) and the bupivacaine group (A5) did not require ketoprofen postoperatively (P < 0.01 vs both groups A6 and A7). Pain scores did not differ significantly among groups. The percentage of patients reporting higher pain scores than before surgery was larger in control group A7 and in bupivacaine groups A5, A6 (83%, 40%, 60%, respectively) and lower in morphine groups A1, A2, A3, A4 (25%, 16%, 27%, 23%, respectively). Group B (ACLR): total consumption of ketoprofen was lowest in groups B2 and B3 (P < 0.001 vs all other treatments and vs control group). The percentage of patients who did not require any rescue analgesic was 60% in group B3, 50% in group B2, 32% in group B5 and 0% in all other groups. No-side effects occurred in any patient. Intra-articular analgesia is safe and effective for arthroscopic knee surgery. Morphine provides a better pain control both in operative knee arthroscopy patients and in ACLR. A 2 mg dose is adequate for operative knee arthroscopy but not for ACLR, where higher dosages are required (5 mg). Pre-emptive intra-articular morphine provides better analgesia than postoperative administration.

Evaluation of arterial compliance in humans.

Compliance is a measure of the elastic properties of arterial vessels and is a function of blood pressure. In recent years new techniques have been developed which allow to measure arterial compliance non invasively and continuously over the range of existing blood pressure values. It has been thus possible to investigate the alterations of arterial compliance in a variety of diseases and to address the physiological factors involved in arterial compliance modulation. This article will focus on the new data available on these issues.

Sympathetic modulation of radial artery compliance in congestive heart failure.

Animal studies have suggested that arterial compliance can be modulated by adrenergic influences. Whether this adrenergic modulation also occurs in humans is still a matter of debate. In the present article we address this issue by examining the relationships between sympathetic tone and arterial compliance in a variety of physiological and pathophysiological conditions. We have found that cigarette smoking, ie, an action that produces a marked sympathetic activation, causes a significant reduction in radial artery compliance, as measured by an echotracking device capable of providing continuous beat-to-beat evaluation of this hemodynamic variable. When expressed as compliance index, ie, as the ratio between the area under the compliance-pressure curve and pulse pressure, the reduction amounted to 35.7 +/- 4.8% (mean +/- SEM) and was independent of the smoking-related blood pressure increase. Furthermore, pharmacological stimulation of adrenergic receptors located in the arterial wall was also shown to affect arterial compliance because the radial artery compliance index was markedly reduced (- 29.5 +/- 3.9%) during phenylephrine infusion in the brachial artery at doses devoid of any systemic blood pressure effect. Evidence was also obtained that the relationship between sympathetic activation and arterial compliance has pathophysiological relevance, because in 17 patients with congestive heart failure (New York Heart Association classes II through IV) there was a significant inverse correlation (r = .62, P < .01) between muscle sympathetic nerve activity (directly measured by microneurography in the peroneal nerve) and radial artery compliance.(ABSTRACT TRUNCATED AT 250 WORDS)