Long-term effects of nitrous oxide anaesthesia on laboratory and clinical parameters in elderly Omani patients: a randomized double-blind study.
ABSTRACT This study examined the long-term effects of nitrous oxide anaesthesia on serum levels of cobalamin and folate, red cell folate levels and haematological parameters, and neurological status in elderly Omani patients.
Sixty-nine consecutive patients undergoing ophthalmic surgery were randomly and double-blind assigned to nitrous oxide or propofol anaesthesia. They met the following entry criteria: age 55 years or above, no major organ failure, no clinical signs or symptoms of cobalamin or folate deficiency, mean cell volume (MCV) </= 96 fl, haematocrit (Hct) higher than 0.3 and no cobalamin and/or folate substitution therapy during the preceding months. Serum levels of cobalamin and folate, red cell folate levels, and haematological parameters were measured prior to anaesthesia and 3-5 weeks later. At that time, the patients also underwent thorough neurological examination.
Data of 51 patients were complete and considered for analysis. In both nitrous oxide and propofol group, the range of exposure time was comparable (+/-1 h). In the nitrous oxide group, a slight but significant decrease in haemoglobin, Hct, and red blood cell count (RBC) (P < 0.001) was observed, whereas there was a mild increase in mean cell haemoglobin (MCH) and mean cell volume (P < 0.05). In addition, there was a significant decrease in serum folate levels (P < 0.05). Hct and RBC decreased slightly in the propofol group (P < 0. 05), whereas there was a small increase in MCH. There was no difference between the two anaesthetics with regard to serum cobalamin and red cell folate levels, but there was a significant decrease in serum folate levels in the nitrous oxide group compared to those in the propofol group. Three patients with pre-existing low red cell folate levels, who were randomized to nitrous oxide anaesthesia, developed clinical symptoms of folate deficiency.
This study showed that short-term (40-80 min) nitrous oxide anaesthesia did not affect cobalamin levels but reduced serum folate levels in this elderly population. Although this reduction was clinically irrelevant, some patients with pre-existing asymptomatic folate deficiency developed nitrous oxide-induced folate deficiency.
Article: Protóxido de nitrógeno[Show abstract] [Hide abstract]
ABSTRACT: El protóxido de nitrógeno u óxido nitroso es un agente volátil que se utiliza en el ámbito médico desde hace más de 150 años. Sus propiedades farmacológicas constituyen su particularidad, ya que posee al mismo tiempo propiedades analgésicas, de tipo no morfínico a través de una acción supraespinal, propiedades euforizantes que le han valido la denominación de «gas de la risa» y propiedades ansiolíticas o incluso anestésicas leves, por lo que se utiliza ampliamente como agente anestésico volátil adyuvante. Con el fin de garantizar su inocuidad y eficacia máxima, se han definido con precisión sus condiciones de empleo, tales como la necesidad de informar previamente al paciente cuando se utiliza con fines analgésicos (reducción del foco de fractura, punciones diversas), un uso exclusivamente asociado a la administración de oxígeno, la utilización de dispositivos especiales para su administración con válvulas antirretorno o sistemas de ventilación específicos en el quirófano para limitar la contaminación ambiental, etc. Por otra parte, este agente posee algunas contraindicaciones, como por ejemplo en pacientes que presentan déficit conocidos o probables de vitamina B12 o de folatos y las ocupaciones aéreas de cavidades no extensibles. Por último, se han descrito algunos efectos indeseables como náuseas, vómitos postoperatorios y efectos neurotóxicos que limitan y condicionan su uso.EMC - Anestesia-Reanimación. 01/2010; 36(4):1–9.
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ABSTRACT: Chronic workplace exposure to high nitrous ox-ide concentrations has been suggested to po-tentially be associated to negative health effects caused by the interference with the vitamin B12, methionine synthase pathway. The objective of the present study was to determine if delivery unit work place ambient air nitrous oxide ex-posure results in detectable hyperhomocysteine-mia or signs of macrocytocis in personnel. Blood samples from thirty healthy female fulltime em-ployees, midwives, aged 43 (range 25-62) years were studied. Routine blood test analysed for plasma homocysteine and blood status; hae-moglobin, mean corpuscular volume, mean cor-puscular haemoglobin concentration, blood sta-tus was analysed once before going on vacation and repeated after at least 10 days' leave, ni-trous oxide free period. Median time weighted average was 41 [10 -547] ppm; 3 out of 11 TWA measurements were above recommended100 ppm limit. Median homocysteine concentrations were 10.7 [5.6 -16] micromol/L with reference limits of 5.0 – 15 micromol/L. Megaloblastic ery-throcytes was not detected in any personnel and no changes in blood status could be detected be-tween before and after a nitrous oxide-free pe-riod. Conclusions: One of 3 delivery units' am-bient air quality measures exceed recommended ranges. No signs of routine blood test pathology could be seen in the personnel studied.01/2011; 3:162-165.
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ABSTRACT: There is emerging evidence related to the effects of nitrous oxide on important perioperative patient outcomes. Proposed mechanisms include metabolic effects linked to elevated homocysteine levels and endothelial dysfunction, inhibition of deoxyribonucleic acid and protein formation, and depression of chemotactic migration by monocytes. Newer large studies point to possible risks associated with the use of nitrous oxide, although data are often equivocal and inconclusive. Cardiovascular outcomes such as stroke or myocardial infarction were shown to be unchanged in previous studies, but the more recent Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia I trial shows possible associations between nitrous oxide and increased cardiovascular and pulmonary complications. There are also possible effects on postoperative wound infections and neuropsychological function, although the multifactorial nature of these complications should be considered. Teratogenicity linked to nitrous oxide use has not been firmly established. The use of nitrous oxide for routine anesthetic care may be associated with significant costs if complications such as nausea, vomiting, and wound infections are taken into consideration. Overall, definitive data regarding the effect of nitrous oxide on major perioperative outcomes are lacking. There are ongoing prospective studies that may further elucidate its role. The use of nitrous oxide in daily practice should be individualized to each patient's medical conditions and risk factors.Journal of Anesthesia 10/2013; · 1.12 Impact Factor