End‐tidal oxygraphy and safe duration of apnoea in young adults and elderly patients

Abstract

SummaryIncreasing numbers of patients presenting for surgery are receiving concurrent medication with low-dose aspirin. We surveyed the opinions and working practices of consultant members of the Neuroanaesthesia Society regarding patients who present for elective intracranial surgery whilst taking this form of medication. Identical questionnaires were sent to 140 members of the society and proffered four main questions: (1) the adherence to any policy of stopping aspirin preoperatively, (2) the preferred method of treatment for excessive bleeding in this context, (3) personal knowledge of haemorrhagic complications in this group of patients, (4) the neurosurgical unit concerned. There were 121 responses (86.4%) of which 116 (82.9%) were valid. Of the respondents, 78 (67.2%) were unaware of a written departmental policy for the discontinuation of pre-operative aspirin treatment and had no personal policy. Thirty-two respondents (27.6%) had a personal policy but were unaware of a written departmental policy; only six respondents (5.2%) stated that a written departmental policy was in place. The mean time suggested for discontinuation of aspirin pre-operatively was 11.3 days (range: 1-42 days). Fifty-one respondents (44.0%) considered that patients taking low-dose aspirin were at increased risk of excessive perioperative haemorrhage and 15 (12.9%) anaesthetists reported having personal experience of such problems. Fifty-seven respondents (49.1%) would use a platelet infusion, alone or in association with other blood products or prohaemostatic agents, if haemorrhagic complications developed. The majority of neuroanaesthetists felt that aspirin was a risk factor for haemorrhagic complications associated with intracranial procedures, but most adopt no policy regarding its preoperative discontinuation.Keywords Surgery; neurosurgical. Analgesics; salicylates, aspirin. ...................................................................................... Correspondence to: D. N. James, Department of Anaesthesia, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK. Accepted: 18 October 1996 Aspirin is increasingly prescribed for its antithrombotic properties [1][2][3][4][5] and more patients are therefore presenting for surgery with dysfunctional circulating platelets. Aspirin is also a common constituent of many 'over the counter ' medications [6].The contribution of low-dose aspirin to increased perioperative blood loss is a contentious issue with conflicting published results from different surgical groups. Data from neurosurgical patients are sparse [7] but aspirin has been identified as an important risk factor in the development of postoperative haematomata following intracranial surgery [8].This survey examined the opinions and working practices of consultant neuroanaesthetists with regard to patients taking low-dose aspirin medication who present for elective intracranial surgery. MethodsIdentical questionnaires with stamped addressed return envelopes were sent to practising consultant members o...

Effects of preoxygenation with the three minutes tidal volume breathing technique in the elderly

“…Maximal preoxygenation is achieved when the alveolar, arterial, tissue, and venous compartment are all filled with oxygen. Hence, if most of the nitrogen in the lung is replaced by oxygen, end tidal expiratory oxygen concentration is reached over 90% as the result of adequate preoxgenation [1]. However, patients with a decreased capacity of oxygen loading or an increased oxygen extraction, or both, are desaturated during apnea much faster than healthy patients [2].…”

Techniques of preoxygenation in patients with ineffective face mask seal

“…Such that 0.9 EtO 2 can be achieved if the leak is small but lower values are likely to be observed when the leak is large. [4] Most studies aim for an EtO 2 value of 0.9 as the endpoint of optimal pre-oxygenation[461213] but there is insufficient data suggesting EtO 2 end point values in presence of the leak due to an improper face mask seal. The authors suggest that EtO 2 can help to gauge the extent of leak and pre-oxygenation should be performed for a longer time if the leak is large.…”

Impacto do acoplamento de máscara facial sobre a oxigenação

“…Não foram encontrados dados na literatura que permitam correlacionar adequadamente se o valor de CEO 2 82,20 poderia ou não ser tão eficaz como o valor de 90. Amaioria dos estudos avaliou a CEO 2 no final de cada período de oxigenação e os poucos que avaliaram a CEO 2 através do tempo não determinaram a concentração do nitrogênio alveolar 5, [15][16][17]25 . Assim, também não foi possível inferir que valores próximos, mas inferiores a 82,20, poderiam ser considerados pelo menos razoáveis, em termos de desnitrogenização.…”