Fernández Méndez, Rocío
(2017)
GlyCon: glycaemic control of stress hyperglycaemia in intensive care units.
PhD thesis, University of Nottingham.
Abstract
Background and aims
Untreated stress-induced hyperglycaemia in critically ill patients has been associated with harmful effects, which can even be fatal. Current evidence about the optimal glycaemic targets, and the most effective and safest methods of glycaemic control (GC) in intensive care units (ICU), is contradictory. GlyCon study aimed to investigate the effectiveness, efficiency and safety of the monitoring and insulin treatment methods for GC implemented in the seven ICUs of an NHS ICU network in the UK. In addition, GlyCon study also aimed to explore the contents of the local protocols for GC of these ICUs, as well as the views of ICU professionals about several aspects of GC.
Methodology
A multi-method study was undertaken, comprising three sub‑studies: (1) a document review of the protocols for GC designed by and implemented at each of the participating ICUs, using techniques of inductive content analysis and descriptive statistics; (2) an online survey to ICU medical and nursing staff, on their opinion about effective GC, and deviations from protocol instructions, which was analysed using descriptive statistics and logistic regression; (3) A retrospective study about the methods and outcomes of GC, based on a review of electronic and manual medical records of a stratified random sample of 146 patients admitted to the seven participating ICUs during 2012 and 2013. The main analyses of association between the exposures and the primary outcome measure (percentage of time with glycaemic levels of 4‑10mmol/L, or TIR, which was transformed into the odds of being within that range at any time, or odds of IR), were mainly based on generalised estimating equations using the logit link, and autoregressive correlation structure. Secondary outcome measures of time‑efficiency and safety were also investigated, and analysed using univariate statistics and multiple log‑linear regression.
Results
The protocols for GC implemented in the seven ICUs differed greatly in their target patients, target glycaemic levels, recommended methods for monitoring, and insulin titration algorithms, among others.
Most of the 40 respondents to the survey agreed that TIR≥75% constitutes good GC and TIR<50% constitutes poor GC. Opinions were divided on intermediate levels of TIR, with professionals having more experience in intensive care tending to rate such intermediate TIR as poor GC more often than their less experienced colleagues. Most of the proposed protocol deviations were considered as major by at least two thirds of the respondents. Professionals’ role (nurse vs. physician) and their number of years of experience were significantly associated with different views.
The blood glucose (BG) monitoring frequencies and insulin hourly dosages, at each glycaemic status, differed by ICU, and between patients with and without diabetes. Non‑adherence to protocol instructions regarding BG monitoring and insulin infusion rates occurred more often than not. The median (IQR) TIR was 91% (81‑96%) and 56% (34‑71%) among patients without and with diabetes, respectively. A number of time-dependent and time-constant factors were associated with higher odds of IR at any time. Time-constant protective factors included: having spent more than 20% of admission time receiving insulin during hyperglycaemia, certain ICU protocols, and lower levels of severity on admission. Time-dependent protective factors were: the number of hours from admission, and the dobutamine and insulin hourly dosages. Time-dependent detrimental factors were: non‑adherence to protocol insulin instructions, the hourly nutritional energy administered, and the hourly dosage of certain drugs, including adrenaline and hydrocortisone.
Conclusions
Protocols for GC, practice of GC, and outcomes of GC, all differed significantly across hospitals. Some protocols seemed more effective, time‑efficient or safe than others, but there was a high incidence of non‑adherence to protocol instructions in all ICUs. This contrasts with professionals rating deviations from protocols as major, more often than not. Certain monitoring and insulin treatment methods for GC were more effective, and some were more time‑efficient than others, particularly among patients without diabetes. There is a clear need for protocols to include different recommendations for patients with diabetes, as well as to formally emphasise the importance of GC also in patients without diabetes. ICU multidisciplinary teams should be involved in the development of these protocols, and their views should be accounted for in research studies about the effectiveness of GC in the ICU.
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