The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction ofanaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group ( H ) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/0.5. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 7.9 to 39.3 i-7.1 ml . M-' and from 73.8 f 20.3 to 94.9 k 18.5 ml . M-' respectively (mean i-s.d., both P i 0 . 0 5 ) . However, heart rate decreased so that cardiac index did not change. 0, delivery decreased significantly (from 389+ 70 to 311 + 6 3 ml.min-"m-*; P<0.05), but was not different to the control group. 0, consumption was maintained by an increase in 0, extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that 0, delivery was similar in the two groups. 0, consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anaesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction of anaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group (H) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/05. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 +/- 7.9 to 39.3 +/- 7.1 ml.M-2 and from 73.8 +/- 20.3 to 94.9 +/- 18.5 ml.M-2 respectively (mean +/- s.d., both P < 0.05). However, heart rate decreased so that cardiac index did not change. O2 delivery decreased significantly (from 389 +/- 70 to 311 +/- 63 ml.min-1.m-2; P < 0.05), but was not different to the control group. O2 consumption was maintained by an increase in O2 extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that O2 delivery was similar in the two groups. O2 consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

olol 80 mg twice daily, metoprolol 100 mg twice daily and atenolol 100 mg once daily was investigated in eight healthy volunteers. 2 Nifedipine 10 mg three times daily did not affect the pharmacokinetics of metoprolol and atenolol whereas nifedipine shortened the time to peak plasma concentration for propranolol by about 1 h. 3 Propranolol, metoprolol and atenolol provoked comparable decreases in heart rate measured at rest and during exercise. The 13-adrenoceptor blocking properties of propranolol, metoprolol and atenolol were not affected by concomitant therapy with nifedipine. 4 The present study did not show significant pharmacokinetic and pharmacodynamic interactions between nifedipine and lipophilic ,8-adrenoceptor blockers.

Methemoglobinemia was suspected in a healthy 19-year-old woman, when the pulse oximeter reading (SpO2) was 88% after a plexus brachialis block with 550 mg (35 ml, 1.5%) prilocaine. The patient was receiving 50% oxygen, and the PaO2 was 48.6 kPa (365 mmHg). After start of methylene blue treatment, with a total dose of 1 mg/kg, the SpO2 showed a gradual increase. This case report emphasises the potential advantage of arterial oxygen saturation monitoring with a pulse oximeter, but also the importance of the correct interpretation of the SpO2 reading.