The blood pressure of upper and lower limbs in elderly patients under general anesthesia for cataract surgery

Background: During anesthesia, measurement of blood pressure is often obtained from the upper
limb. In cataract surgery the arms are not easily available and blood pressure reading may be
obtained from the lower limbs. The relationship between the blood pressure measurements at the
two sites in elderly patients undergoing general anesthesia is unclear. This study was designed to
evaluate the difference observed in systolic blood pressure (SBP) taken from the upper limb (UL)
and the lower limb (LL) in geriatric patients under general anesthesia for cataract surgery.
Material & Methods: 113 Patients undergoing cataract surgery in supine position were selected.
The blood pressure cuff was placed on right arm, right leg, left arm and left leg respectively. Before
and then 20 minutes after induction of anesthesia, the systolic blood pressure (SBP) readings were
taken by finger palpation from the 4 limbs using the manual mercury sphygmomanometer. The
same sphygmomanometer was used to make consecutive recordings from 4 limbs. The data were
analyzed using paired t-test and ANOVA.
Results: We found that SBP reading taken from the legs are significantly higher than arm
pressures (P<0.001, ANOVA). There was no significant difference between left and right SBP at the
arms and legs. There was significant difference between preanesthetic SBP and that of measured 20
min after induction of anesthesia (P<0.001, paired t-test).The mean SBP measured from right UL
and right LL during anesthesia was 117.10±9.70 mmHg and 124.91±9.48 mmHg respectively.
Conclusion: Our study shown that although in elderly patients, higher SBP readings obtained
from the LL compared with the UL, but the difference in pressure is not clinically significant. The
increased SBP in the LL of geriatric patients may be due to progressively decreased compliance of
peripheral arteries. Our results suggest that indirect blood pressure measurement in legs may be an
acceptable method during anesthesia for cataract surgery because it yields values that are at an
approximate from those recorded at the arms.