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Mercury-independent devices are increasingly being used in clinical practice as mercury will soon be removed from clinical use as a result of environmental, health and safety concerns. The aim of this study was to evaluate the accuracy of a portable aneroid device in an adult population at high altitude by following the part of the protocol of the British Hypertension Society regarding comparison between device and observer. We examined 10 subjects in Cerro de Pasco, Peru, which is situated 4370 m above sea level. The aneroid device was initially calibrated at both high altitude and at sea level to ensure optimal function. Validation of the device was undertaken at high altitude by connecting it in parallel to two mercury sphygmomanometers. Eleven sequential same-arm measurements were taken from each subject by two trained observers, alternating between mercury sphygmomanometry and the aneroid device. Simultaneous mercury readings were also recorded for additional analysis. During calibration, all 60 comparisons between the aneroid and mercury sphygmomanometers were within 3 mm Hg both at sea level and at high altitude. At validation, the device achieved an A grade for both systolic and diastolic pressures and also fulfilled the requirements of the Association for the Advancement of Medical Instrumentation. The mean and standard deviation for systolic and diastolic pressures, respectively, were -1.32 (4.3) mm Hg and 3.7 (4.7) mm Hg in sequential analysis and -0.7 (2.6) mm Hg and -3.3 (2.7) mm Hg in simultaneous analysis. We conclude that the Riester-Exacta portable aneroid device can be recommended for use in an adult population at high altitude.

Objective: To investigate the maternal cardiovascular adaptation in pregnancy at high altitude, compared with that at sea level., Design: Cross sectional study., Setting: Two maternity units providing routine antenatal care: one at 4370 m above sea level (Cerro de Pasco, Peru) and one at sea level (Lima, Peru)., Population: We examined 175 pregnant women at 5-41 weeks of gestation and 16 non-pregnant controls resident at high altitude and 132 pregnant women and 18 non-pregnant controls at sea level., Methods: Two-dimensional and M-mode echocardiography of the left ventricle., Main Outcome Measures: Maternal cardiac output and left ventricular longitudinal and transverse systolic function indices., Results: Pregnancy at high altitude, compared with sea level, is associated with 11% lower birthweight and 31% lower maternal cardiac output, due to 15% lower stroke volume and 11% lower heart rate. The lower stroke volume was due to a lower preload and impaired longitudinal and transverse left ventricular systolic function. Mean arterial pressure was about 8% lower during pregnancy at high altitude versus sea level. Pregnant women at high altitude failed to expand their intravascular space to the same extent as the sea level group: cardiac output increased by 17%, left atrial diameter by 12% and end-diastolic diameter by 1% at high altitude versus 41%, 25% and 5%, respectively, at sea level., Conclusions: Pregnancy at high altitude, compared with sea level, is characterised by lower cardiac output due to lower heart rate and lower stroke volume and reduced expansion of the maternal intravascular space compared with the non-pregnant state.

Background: Pregnancy at high altitude has been associated with intrauterine growth restriction and preeclampsia. These conditions, at sea level, have been linked to increased hematocrit and blood viscosity. The aim of this study was to investigate the effect of high altitude on maternal hemorheology., Methods: This was a cross-sectional study. We examined 94 pregnant women at 10-38 weeks of gestation resident at high altitude (4370 m above sea level) and 75 at sea level, and 24 and 17 nonpregnant women at each altitude, respectively. Blood and plasma viscosity, hematocrit, plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting., Results: Pregnancy at high altitude, compared to sea level, is characterized by higher hematocrit, blood viscosity (at high shear rate), plasma viscosity, total protein and fibrinogen concentrations (25%, 38%, 7%, 13.3% and 25%, respectively) and 6% lower albumin concentration. Nonpregnant women at high altitude, compared to sea level, had higher hematocrits, blood viscosity, plasma viscosity, total protein and fibrinogen concentrations (25%, 55%, 18%, 26% and 98%, respectively) and 13% lower albumin concentration., Conclusion: Pregnancy at high altitude compared to sea level is characterized by increased blood viscosity as a result of increased hematocrit and plasma viscosity.

Objective: Pregnancy at high altitude has been associated with increased prevalence of pre-eclampsia and reduced maternal oestrogen levels, factors that have been associated with endothelial dysfunction. The aim of this study was to examine the effect of high altitude (4370 m above sea level) on endothelial function during pregnancy as assessed by a non-invasive method., Design: Cross-sectional study., Setting: Two maternity units providing routine antenatal care: one at high altitude (District General Hospital--IPSS in Cerro de Pasco, Peru) and one at sea level (Instituto Materno-Perinatal in Lima, Peru)., Population: Sixty pregnant women at 6-42 weeks of gestation resident at high altitude (Cerro de Pasco, Peru, 4370 m above sea level) and 54 at sea level (Lima, Peru). Comparisons were performed also in 11 and 14 non-pregnant women at each altitude, respectively., Methods: Endothelial function was assessed by flow-mediated dilatation of the brachial artery using high-resolution ultrasound., Main Outcome Measures: Differences in flow mediated dilatation of the brachial artery in two groups of pregnant women, one at high altitude and one at sea level., Results: Both at high altitude and sea level flow-mediated dilatation of the brachial artery increased in the first two trimesters to levels 32% higher than non-pregnant controls. However, in the third trimester, flow-mediated dilatation of the brachial artery was lower than non-pregnant levels. Resting vessel size increased during pregnancy by 15% compared with non-pregnant controls at term, with no difference between the two populations at high and low altitude. Pregnancy at high altitude, compared with sea level, was associated with 59% lower baseline blood flow and 76% higher reactive hyperaemia. Similarly, non-pregnant controls at high altitude compared with sea level demonstrated similar flow-mediated dilatation of the brachial artery and 40% lower resting blood flow of the brachial artery. However, the difference in reactive hyperaemia did not reach statistical significance., Conclusion: These data suggest that, during pregnancy at high altitude, endothelial function, as assessed by flow-mediated dilatation of the brachial artery, is not impaired.

Objective: To investigate the effect of environmental hypoxia at 4300-m altitude on the maternal serum concentration of insulin-like growth factor binding protein-1 (IGFBP-1)., Methods: We conducted a cross-sectional study of 108 pregnant women in Peru, 62 from high altitude (4300 m, 14100 ft) and 46 from sea level at 14-42 weeks' gestation. For comparison, 20 healthy nonpregnant women (ten from high altitude and ten from sea level) were also examined. Total and nonphosphorylated IGFBP-1 were measured in maternal serum., Results: Both total and nonphosphorylated IGFBP-1 were higher at high altitude than at sea level in the pregnant groups (ratio = 1.28, P =.008, and ratio = 1.45, P =.003, respectively), and there was significant interaction between high altitude and sea level (P =.037 and P =.043, respectively). The threshold model showed that the difference became significant from 25 weeks' gestation onwards., Conclusion: Before 25 weeks of pregnancy, there was no significant difference in IGFBP-1 between women living at high or low altitude, suggesting that the increased IGFBP-1 at high altitude is unlikely to be related to inadequate trophoblast invasion resulting in placental hypoxia. In the second half of pregnancy, the maternal and fetal demands increase dramatically, and low atmospheric oxygen with resulting maternal systemic hypoxemic hypoxia may cause placental hypoxia. This stimulates increased production of IGFBP-1, which in turn restricts the insulin-like growth factor-mediated fetal growth as an adaptive mechanism to prevent worsening of the fetoplacental hypoxia.

Objective: To assess insulin sensitivity and beta-cell function associated with lower maternal fasting plasma glucose levels at high altitude compared with sea level., Research Design and Methods: We studied 215 pregnant women at 8-42 weeks of gestation in Peru. The women were recruited from Cerro de Pasco, which is situated 4,370 m (14,340 feet) above sea level, and Lima, which is at sea level. We also examined 53 nonpregnant control subjects (22 in Cerro de Pasco and 31 in Lima). Fasting plasma glucose, insulin, C-peptide, and proinsulin concentrations were measured in samples obtained from the antecubital vein between 8:00 a.m. and 10:00 a.m. after an overnight period of fasting for 10-14 h Insulin resistance and beta-cell function were calculated using homeostasis model assessment., Results: Fasting C-peptide levels and beta-cell function were similar, fasting concentrations of insulin and proinsulin were lower, and insulin sensitivity was higher at high altitude compared with sea level., Conclusions: Maternal fasting plasma glucose that is lower at high altitude than at sea level in the presence of similar insulin secretion is associated with higher peripheral insulin sensitivity. This may partly explain the lower birth weights at high altitudes.

Objective: To compare plasma glucose in pregnant women living at very high altitude; pregnant women living at sea level; non-pregnant women living at very high altitude; and non-pregnant women living at sea level., Design: Cross-sectional study., Participants: Ninety-four pregnant women attending for routine antenatal care at 8-42 weeks of gestation in Cerro de Pasco, Peru which is situated 4370 m above sea level; 122 pregnant women in Lima, which is at sea level; 22 non-pregnant women in Cerro de Pasco; and 31 non-pregnant women in Lima., Methods: Plasma glucose concentrations were measured in samples obtained from the antecubital vein between 8 am and 10 am after an overnight period of fasting for at least 10 hours., Results: Fasting plasma glucose was lower in women at high altitude than in those at sea level, and in both groups the level was lower in pregnant women than in non-pregnant controls. The body mass index was not significantly different between all four groups, and it did not have a significant independent contribution in explaining the variance in fasting plasma glucose., Conclusion: Women native at high altitude have lower plasma glucose concentrations before and during pregnancy than those at sea level.