British journal of anaesthesia
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Simultaneous measurement of ascending aorta and radial artery pressure shows that mean and diastolic pressures (DP) are in close agreement in normotensive adults, while systolic pressures (SP) are not. However, in the aortic pressure wave, a second systolic peak appears with increasing age and increases to represent the SP by age 32 yr, while in the radial artery, a second systolic deflection appears by age 40 yr. We suggest that the second radial systolic wave, sometimes seen during radial arterial pressure monitoring in older hypertensives, represents the aortic SP. We set out to evaluate whether the aortic and radial second systolic peaks agree, and since doubts exist about the agreement between aortic and radial DP in elderly hypertensive patients, we also assessed that relationship. ⋯ The second radial pressure peak agreed with that in the aorta within a mean of 0.6 (SD 1.5) mm Hg. The difference between DP in the aorta and radial artery was -1.4 (2) mm Hg. The radial-aortic SP and pulse pressure differences were 5.9 (7.6) and 7.3 (7.6) mm Hg, respectively. These results confirm that when the radial artery pressure wave shows a first and second, or only a second systolic shoulder/peak (on the right side of the pressure wave), the second represents the maximal ascending aortic SP, and that the radial and aortic DP are equivalent, even in older hypertensive patients.
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Case Reports
Unintentional arterial puncture during cephalic vein cannulation: case report and anatomical study.
The cephalic antebrachial vein is often used for venous access. However, superficial radial arteries of the forearm are known and unintentional arterial puncture can result from attempts to cannulate the lateral veins of the arm. ⋯ If venous cannulation is attempted at the radial side of the wrist, palpation for pulsation should reduce the danger of arterial puncture.
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Subanaesthetic concentrations of volatile anaesthetics significantly affect the respiratory response to hypoxia and hypercapnoeia. Individuals with an inherited blunted respiratory drive are more affected than normal individuals. To test the hypothesis that subjects with blunted hypercapnoeic respiratory drive are diversely affected by different anaesthetics, we studied the effects of three volatile anaesthetics on the control of breathing in C3H/HeJ (C3) mice, characterized by a blunted hypercapnoeic respiratory response. ⋯ In C3 mice, spontaneous ventilation was less affected during sevoflurane compared with either isoflurane or desflurane anaesthesia. However, the RR response to hypercapnoeia was abolished at 0.5 MAC for all the anaesthetic agents and remained depressed even at the end of recovery. Our data suggest that different volatile anaesthetics have varying effects on the control of breathing frequency but all block the respiratory response to carbon dioxide. Therefore, a genetic predisposition to a blunted carbon dioxide response represents a susceptibility factor that interacts with hypercapnoeic hypoventilation during maintenance of anaesthesia and in the emergence from anaesthesia, regardless of the agent used.