The pressor response to intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). The effect of pretreatment with lignocaine 1.5 mg kg-1, magnesium sulphate 40 mg kg-1 or alfentanil 10 micrograms kg-1 on this pressor response was studied in 69 patients with moderate to severe GPH. Systolic arterial pressure exceeded baseline values for the first 5 min after tracheal intubation in the lignocaine group, with a peak increase of 31.6 (SEM 3.6) mm Hg at 2 min after intubation, but no mean increase in pressure occurred in the two other groups. Following intubation, six of 24 mothers in the alfentanil group, six of 21 in the lignocaine group and one of 24 in the magnesium group (P less than 0.05) exhibited a systolic arterial pressure (SAP) greater than 180 mm Hg sustained for 2 min or more. Alfentanil caused the least change in heart rate, but resulted in significant fetal depression.
The pressor response to tracheal intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). We have studied the effect of pretreatment with magnesium sulphate 40 mg kg-1 or 30 mg kg-1 with alfentanil 7.5 micrograms kg-1 on this pressor response in 38 patients with moderate to severe GPH. The magnesium-alfentanil combination produced better control of arterial pressure and heart rate than magnesium alone, although both techniques provided good cardiovascular control. There was no significant difference in fetal outcome between groups. Both pretreatment methods produced satisfactory control of catecholamine release.
Summary. Ten patients with gestational proteinuric hypertension were studied with a Swan‐Ganz thermodilution haemodynamic catheter before, during and after plasma volume expansion. Five patients were treated with dihydralazine before volume expansion and five after volume expansion. Before treatment all patients had a low pulmonary capillary wedge pressure (PCWP), low cardiac index (CI) and high systemic vascular resistance (SVR). Following volume expansion the PCWP and CI increased, the SVR decreased but the blood pressure (BP) was unchanged. Administration of dihydralazine following volume expansion led to a decrease in PCWP, an increase in CI and a decrease in SVR and BP. Dihydralazine alone caused an increase in heart rate, PCWP, and CI, and a decrease in SVR and BP. Volume expansion, by increasing CI and decreasing SVR, may be of therapeutic benefit in the severely hypertensive pregnant patient with a low cardiac index.
A self-tuning, closed-loop computerized system was used to maintain atracurium-induced neuromuscular blockade in patients undergoing routine lower abdominal gynaecological surgery. The controller is based on a unique algorithm which utilizes a bi-exponential model wherein two of the variables are estimated on-line. This enables the system to optimize the sizes of subsequent bolus doses according to patient sensitivity. In this study an initial bolus of 0.3 mg kg-1 was given in a trade-off aimed at achieving earlier intubating conditions rather than taking control of relaxation ab initio and obtaining the pre-programmed setpoint of 15% single twitch response (STR) without overshoot. This was successful in all of the 11 patients studied, the mean time from injecting the bolus to intubation being 2.47 (SD 0.95) min and the drug maintenance requirement being 0.34 (0.07) mg kg-1 h-1. This provided a mean value of 10.26% STR with minimal oscillation about the setpoint (average standard deviation = 4.31 (2.53)) for up to 147 min.
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