SummaryDespite current recommendations on the management of pre-operative anaemia, there is no pragmatic guidance for the diagnosis and management of anaemia and iron deficiency in surgical patients. A number of experienced researchers and clinicians took part in an expert workshop and developed the following consensus statement. After presentation of our own research data and local policies and procedures, appropriate relevant literature was reviewed and discussed. We developed a series of best-practice and evidence-based statements to advise on patient care with respect to anaemia and iron deficiency in the peri-operative period. These statements include: a diagnostic approach for anaemia and iron deficiency in surgical patients; identification of patients appropriate for treatment; and advice on practical management and follow-up. We urge anaesthetists and peri-operative physicians to embrace these recommendations, and hospital administrators to enable implementation of these concepts by allocating adequate resources.

Previously undiagnosed anaemia is common in elective orthopaedic surgical patients and is associated with increased likelihood of blood transfusion and increased perioperative morbidity and mortality. A standardized approach for the detection, evaluation, and management of anaemia in this setting has been identified as an unmet medical need. A multidisciplinary panel of physicians was convened by the Network for Advancement of Transfusion Alternatives (NATA) with the aim of developing practice guidelines for the detection, evaluation, and management of preoperative anaemia in elective orthopaedic surgery. A systematic literature review and critical evaluation of the evidence was performed, and recommendations were formulated according to the method proposed by the Grades of Recommendation Assessment, Development and Evaluation (GRADE) Working Group. We recommend that elective orthopaedic surgical patients have a haemoglobin (Hb) level determination 28 days before the scheduled surgical procedure if possible (Grade 1C). We suggest that the patient's target Hb before elective surgery be within the normal range, according to the World Health Organization criteria (Grade 2C). We recommend further laboratory testing to evaluate anaemia for nutritional deficiencies, chronic renal insufficiency, and/or chronic inflammatory disease (Grade 1C). We recommend that nutritional deficiencies be treated (Grade 1C). We suggest that erythropoiesis-stimulating agents be used for anaemic patients in whom nutritional deficiencies have been ruled out, corrected, or both (Grade 2A). Anaemia should be viewed as a serious and treatable medical condition, rather than simply an abnormal laboratory value. Implementation of anaemia management in the elective orthopaedic surgery setting will improve patient outcomes.

Clinicians lack a practical method for measuring CBF rapidly, repeatedly, and noninvasively at the bedside. A new noninvasive technique for estimation of cerebral hemodynamics by use of near-infrared spectroscopy (NIRS) and an intravenously infused tracer dye is proposed. Kinetics of the infrared tracer indocyanine green were monitored on the intact skull in pigs. According to an algorithm derived from fluorescein flowmetry, a relative blood flow index (BFI) was calculated. Data obtained were compared with cerebral and galeal blood flow values assessed by radioactive microspheres under baseline conditions and during hemorrhagic shock and resuscitation. Blood flow index correlated significantly (rs = 0.814, P < 0.001) with cortical blood flow but not with galeal blood flow (rs = 0.258). However, limits of agreement between BFI and CBF are rather wide (+/- 38.2 +/- 6.4 mL 100 g-1 min-1) and require further studies. Data presented demonstrate that detection of tracer kinetics in the cerebrovasculature by NIRS may serve as valuable tool for the noninvasive estimation of regional CBF. Indocyanine green dilution curves monitored noninvasively on the intact skull by NIRS reflect dye passage through the cerebral, not extracerebral, circulation.

Inhalation of nitric oxide (NO) and prostacyclin (PGI2) may induce selective pulmonary vasodilation and-by improving ventilation-perfusion ratio in ventilated areas of the lung-increase Pao2 in patients with acute lung injury. To assess the therapeutic efficacy of both compounds, dose-response curves were established in patients with adult respiratory distress syndrome (ARDS). Patients received both PGI2 (doses of 1, 10, and 25 ng/kg/min) and NO (concentrations of 1, 4, and 8 ppm). Cardiorespiratory parameters were assessed at control, at each drug concentration, and after withdrawal of NO and PGI2. PGI2 resulted in a significant, dose-dependent and selective reduction of pulmonary artery pressure (PAP) from 35.1 +/- 6.3 mm Hg at control to 33.1 +/- 4.8 (1 ng/kg/min), 31.3 +/- 4.8 mm Hg (10 ng/kg/min) and 29.6 +/- 4.5 mm Hg (25 ng/kg/min), respectively. Inhaled NO reduced PAP from 34.5 +/- 5.6 to 32.1 +/- 5.9 mm Hg at 4 ppm, and to 31.8 +/- 6.1 mm Hg at 8 ppm, respectively, with no effect at 1 ppm. Pao2/Flo2 ratio increased from 105 +/- 37 to 125 +/- 56 mm Hg (range of increase: 0 to 57 mm Hg) at PGI2 10 ng/kg/min and to 131 +/- 63 mm Hg (range: -5 to 89 mm Hg) at 25 ng/kg/min with no effect at 1 ng/kg/min. NO improved Pao2 (e.g., from 116 +/- 47 to 167 +/- 86 mm Hg at 8 ppm) and reduced intrapulmonary shunt at all doses tested. We conclude that both inhaled PGI2 and NO may induce selective pulmonary vasodilation and increase Pao2 in severe ARDS.

In anesthetized pigs submitted to lethal anemia, hyperoxic ventilation enabled survival for 6 h without signs of circulatory failure.

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In anesthetized dogs ventilated with room air and hemodiluted to a Hb of 7 g per dL, simple oxygen therapy by HV (FIO2 1.0) rapidly improves tissue oxygenation and permits extended hemodilution to Hb of 5.8 g per dL until the HV-induced effects are lost.