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.
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Article: Protossido d’azoto[Show abstract] [Hide abstract]
ABSTRACT: II protossido d’azoto è un agente volatile utilizzato in campo medico da più di 150 anni. Le sue proprietà farmacologiche ne costituiscono la particolarità, poiché esso presenta al tempo stesso proprietà analgesiche, di tipo non morfinico, che passano attraverso un’azione sopraspinale, proprietà euforizzanti che gli valgono la denominazione di «gas esilarante» e proprietà ansiolitiche, o anche debolmente anestetiche, che lo fanno ampiamente proporre come agente anestetico volatile adiuvante. Le sue condizioni di impiego sono ormai precisate per garantirne l’innocuità e l’efficacia massima come un’informazione preliminare del paziente per un uso a fini analgesici (riduzione di un focolaio di frattura, punture diverse), un uso associato esclusivamente alla somministrazione di ossigeno, dei dispositivi particolari di somministrazione con valvole antireflusso o dei sistemi di ventilazione specifici nel blocco operatorio per limitare l’inquinamento ambientale. Tale agente antico possiede comunque un certo numero di controindicazioni al suo impiego, tra le quali si trovano i pazienti che presentano deficit noti o probabili di vitamina B12 o di folati e i versamenti aerei di cavità non estensibili. Infine,è riferito un certo numero di effetti indesiderati quali le nausee e i vomiti postoperatori, gli effetti neurotossici e via dicendo, che giustificano, infine, il suo impiego ragionato e, probabilmente, limitato.01/2010; 15(4):1–8. DOI:10.1016/S1283-0771(10)70256-5
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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; 28(3). DOI:10.1007/s00540-013-1729-y · 1.12 Impact Factor