In 2019-20, QARRC undertook a statewide retrospective observational study of Intraoperative Hypotension in Elderly Patients in QLD hospitals, with results presented at the ANZCA ASM (2021).
Findings
Background | Intraoperative hypotension (IOH) is associated with organ injury (1) and mortality in older patients (2). Suggested targets include: mean arterial pressure (MAP) > 65mmHg or, <20% drop from baseline systolic blood pressure (SBP). IOH treatment thresholds used in clinical practice in Australia have not been defined. We aimed to identify the prevalence and treatment thresholds for IOH in Queensland.
Method | Data were collected over 30 days from 10 Queensland hospitals for patients aged ≥65 years who underwent non-cardiac surgery. IOH was defined as MAP <65mmHg or >20% drop from preinduction SBP. Data on vasopressor therapy, stroke, AKI, and myocardial injury and death at 30 days were also collected. Anaesthetists at each site were invited to complete an anonymous survey on their intended treatment thresholds for IOH.
Results | Demographics & Frequency of IOH
N = 1707 patients, including: 44.7% female, 58.6% aged 65-74 years, 50.1% ASA 3, 93.5% underwent GA, 25.5% invasive blood pressure monitoring.
IOH was extremely common (see Figure 1): 90.5% patients with >20% drop in SBP, and 58.4% patients with MAP <65mmHg. Nadir blood pressure most frequently occurred during the first 30 mins of surgery (56.3%).
Results | Survey
Survey was completed by 237 anaesthetists. 71.3% reported using SBP and 93.2% reported using MAP to guide fluid and vasopressor therapy.
IOH Definition 1: >20% drop in preinduction SBP
Intended (survey): 70% would treat at ≤20% drop in SBP.
Observed: Only 20% did; 80% treated below 20% SBP drop.
IOH Definition 2: MAP <65mmHg
Intended (survey): 49% would treat at MAP ≥ 65mmHg.
Observed: 65% treated above MAP 65mmHg.
Results | Outcomes
Postoperative myocardial injury, AKI, or death within 30 days occurred in 139 patients (8.1%) — AKI 99 (5.8%), myocardial injury 28 (1.6%), and 30 day mortality 25 (1.5%).
Intraoperative MAP <65mmHg was associated with post-operative AKI (OR = 1.772, p = 0.018, 95% CI [1.104, 2.845]).
Discussion | Most patients aged ≥65 years were exposed to IOH during surgery in this Australian cohort. Many anaesthetists may be targeting treatment thresholds below those suggested in literature. Tighter control of IOH has substantial potential as a treatment target. Trials are awaited to address the impact of IOH treatment on patient outcomes.
References | [1] Wesselink EM, Kappen TH, Torn HM, Slooter AJC, and van Klei WA. Intraoperative hypotension and the risk of postoperative adverse outcomes: a systematic review. Br J Anaesth. 2018;121(4):706-21. [2] Bijker JB, van Klei WA, Vergouwe Y, Eleveld DJ, van Wolfswinkel L, Moons KG, et al. Intraoperative hypotension and 1-year mortality after noncardiac surgery. Anesthesiology. 2009;111(6):1217-26.
Acknowledgements
Site Leads
| PAH | Stefan Saric & Adeel Aftab |
| GCUH | Ben Cahill & Harry Burnett |
| SCUH | Anna Pietsch & Cecilia Xu |
| Townsville | Nicole Galletly |
| Redland | Hamish Raniga |
| QEII | Esmond Hii, Matthew Greber & Louis Yin |
| Redcliffe | Leonie Roberts |
| RBWH | Rom Ranasinghe & Matthew Black |
| Cairns | Tessa Finney-Brown |
| Mackay | Casey Steele |
| Rockhampton | Siobhan Lane & Robert Hasell |
Collaborators
Ali Abbosh
Andrew Polukoshko
Aran Sandrasegaran
Edward Thornley
Jennifer Batchelor
Jesse Mclellan
Joyce Leung
Kathryn Mack
Maxwell Porter
Niranjika Jeyarajan
Peter Fardoulys
Rebecca Chan
Rebecca Johnstone
Ronald Lam
Steve Ayotte
Tanvi Karnik
Tommy Tseng
Daniel Patti
Eddie Chen
Joshua Davis
Kyle Linfield
Mitchell Baker
William Curtis
Alexander Kelly
Annalisse Leikvold
Christopher Miller
Kavita Sen
Matthew Judd
Tommy Lam
Tessa Finney Brown
Alex Kelly
Isaac Mok
Kenny Cheer
Louis Yin
Sabrina Chan