Oxygenation Impairment during Anesthesia: Influence of Age and Body Weight.

Hedenstierna, Göran; Tokics, Leif; Scaramuzzo, Gaetano; Rothen, Hans Ulrich; Edmark, Lennart; Öhrvik, John (2019). Oxygenation Impairment during Anesthesia: Influence of Age and Body Weight. Anesthesiology, 131(1), pp. 46-57. Wolters Kluwer Health 10.1097/ALN.0000000000002693

Preview

Text 2019 - Hadenstierna - Anesthesiology - PMID 31045901.pdf - Published Version Available under License Publisher holds Copyright. Download (922kB) | Preview

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

During anesthesia oxygenation is impaired, especially in the elderly or obese, but the mechanisms are uncertain.

WHAT THIS ARTICLE TELLS US THAT IS NEW

Pooled data were examined from 80 patients studied with multiple inert gas elimination technique and computed tomography. Oxygenation was impaired by anesthesia, more so with greater age or body mass index. The key contributors were low ventilation/perfusion ratio (likely airway closure) in the elderly and shunt (atelectasis) in the obese.

BACKGROUND

Anesthesia is increasingly common in elderly and overweight patients and prompted the current study to explore mechanisms of age- and weight-dependent worsening of arterial oxygen tension (PaO2).

METHODS

This is a primary analysis of pooled data in patients with (1) American Society of Anesthesiologists (ASA) classification of 1; (2) normal forced vital capacity; (3) preoxygenation with an inspired oxygen fraction (FIO2) more than 0.8 and ventilated with FIO2 0.3 to 0.4; (4) measurements done during anesthesia before surgery. Eighty patients (21 women and 59 men, aged 19 to 69 yr, body mass index up to 30 kg/m) were studied with multiple inert gas elimination technique to assess shunt and perfusion of poorly ventilated regions (low ventilation/perfusion ratio [VA/Q]) and computed tomography to assess atelectasis.

RESULTS

PaO2/FIO2 was lower during anesthesia than awake (368; 291 to 470 [median; quartiles] vs. 441; 397 to 462 mm Hg; P = 0.003) and fell with increasing age and body mass index. Log shunt was best related to a quadratic function of age with largest shunt at 45 yr (r =0.17, P = 0.001). Log shunt was linearly related to body mass index (r = 0.15, P < 0.001). A multiple regression analysis including age, age, and body mass index strengthened the association further (r = 0.27). Shunt was highly associated to atelectasis (r = 0.58, P < 0.001). Log low VA/Q showed a linear relation to age (r = 0.14, P = 0.001).

CONCLUSIONS

PaO2/FIO2 ratio was impaired during anesthesia, and the impairment increased with age and body mass index. Shunt was related to atelectasis and was a more important cause of oxygenation impairment in middle-aged patients, whereas low VA/Q, likely caused by airway closure, was more important in elderly patients. Shunt but not low VA/Q increased with increasing body mass index. Thus, increasing age and body mass index impaired gas exchange by different mechanisms during anesthesia.

Interest & Impact

Downloads

223 since deposited on 31 Jul 2019
39 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item