Hypoxemia in the presence or absence of systemic inflammation does not increase blood lactate levels in healthy volunteers.

PURPOSE: Elevated lactate levels are a sign of critical illness and may result from insufficient oxygen delivery. We investigated whether hypoxemia and/or systemic inflammation, results in increased lactate levels in healthy volunteers. MATERIALS AND METHODS: 30 healthy volunteers were exposed to either 3.5 h of hypoxemia (FiO2 ± 11.5%), normoxemic endotoxemia (FiO2 21%, administration of 2 ng/kg endotoxin), or hypoxemic endotoxemia (n = 10 per group). Blood lactate, hemoglobin, SpO2, PaO2, PaCO2, pH, and hemodynamic parameters were serially measured. RESULTS: Hypoxemic treatment resulted in lower SpO2 (81.7 ± 2.6 and 81.4 ± 2.4% in the hypoxemia and hypoxemic endotoxemia groups, respectively) and hyperventilation with a PaCO2 decrease of 0.8 ± 0.5 and 1.5 ± 0.6 kPa and an increase in pH. Arterial oxygen content (CaO2) decreased by 20.5 ± 2.9 and 23.5 ± 4.4%, respectively. Lactate levels were slightly, but significantly higher in both hypoxemic groups compared with the normoxemic endotoxemia group over time (p < 0.0001 for both groups), but remained below 2.3 mmol/L in all subjects. Whereas PaO2 and SpO2 did not correlate with lactate levels, PaCO2, pH and CaO2 did. CONCLUSIONS: Hypoxemia, in the absence or presence of inflammation does not result in relevant increases of lactate. The small increases in lactate observed are likely to be due to hyperventilation-related decreases in glycolysis.

Effect of early achievement of physiologic resuscitation goals in septic patients admitted from the ward on the kidneys.

PURPOSE: The aim of the study was to evaluate if early achievement of physiologic goals of resuscitation in critically ill septic patients admitted from the ward may prevent acute kidney injury (AKI). MATERIALS AND METHODS: Patients admitted to the intensive care unit (ICU) with a diagnosis of sepsis were retrospectively identified. Mean arterial pressure greater than 65 mm Hg, central venous pressure greater than 8 mm Hg, and central venous oxygenation greater than 70% achieved within 6 hours after ICU consultation at the ward was considered early achievement. Acute kidney injury was defined by the RIFLE criteria. RESULTS: Of 85 patients, 29% achieved all goals within 6 hours, 42% had late or no achievement of goals, and 28% had incomplete documentation of goals. Of these, 52% developed AKI. Patients who eventually developed AKI had a significantly higher creatinine level at ICU consultation before resuscitation. Delay in achievement of goals results in a 3.4% creatinine level rise per hour in multivariate analysis (P = .03). The development of AKI was significantly influenced by delayed achievement of physiologic goals on the ICU (P = .02). CONCLUSIONS: Although most of AKI occurred before ICU consultation, early physiologic resuscitation and achievement of hemodynamic goals on the ICU is associated with a decrease in development of AKI of septic patients admitted from the ward.

Oscillometric blood pressure measurements: differences between measured and calculated mean arterial pressure.

Mean arterial pressure (MAP) is often used as an index of overall blood pressure. In recent years, the use of automated oscillometric blood pressure measurement devices is increasing. These devices directly measure and display MAP; however, MAP is often calculated from systolic blood pressure (SBP) and diastolic blood pressure (DBP) as displayed by the device. In this study we have analysed measured and calculated MAP, obtained by two different oscillometric BP measurement devices in two different patient cohorts. The first cohort included 242 healthy subjects (male 40.5%, 50+/-13 years). BP measurements were performed with a Welch Allyn 5300P device. We found a small but significant difference between measured MAP and calculated MAP (MAP(m-c:) -1.8 mmHg, range -5.7 to 12.9 mmHg, p < 0.001). MAP(m-c) showed a significant, but weak correlation with DBP and SBP. The second cohort included included 134 patients with glomerular diseases (male 63%, 50+/14 years). BP measurements were performed with a Dinamap 487210 device. In this group we also observed a small difference between measured MAP and calculated MAP (+1.7 mmHg, range -15.3 to 28.2 mmHg, p<0.001). MAP (m-c) correlated with age, all blood pressure indices and heart rate. An overall analysis showed that age, SBP, DBP, and type of device are all independently related to MAP (m-c). There is a significant difference between measured and calculated MAP. The difference is small on average; however, this MAP(m-c) can be large in the individual patient. Moreover, there are differences of reported MAP between devices. Our data suggest that calculated and measured MAP cannot be used interchangeably.