The proportion of complications of first group / second group: hypotension: 1.4 / 2.9%; shivering: 0 / 4.3%, nausea and vomiting: 0 / 1.4%; headache: 1.4 / 2.9%; backache: 4.3 / 8.6%, urinary retention: 2.9 / 5.7%.