Original article
Fever and agitation in elderly ICU patients: A descriptive study

https://doi.org/10.1016/j.iccn.2010.02.003Get rights and content

Summary

Objective

To investigate the association between fever and agitation in elderly, critically ill patients.

Setting

Medical–surgical Intensive Care Unit (ICU) of a Greek, tertiary care hospital.

Research methodology

Descriptive, quantitative study conducted from October 2005 to September 2006. Patient temperature was measured by a tympanic membrane or an axillary thermometer. Agitation–Sedation scale was used for evaluating agitation. Variables found to contribute to agitation in previous studies were also collected.

Results

One hundred sixty-one patients ≥65 years, who were consecutively admitted to the ICU, were enrolled. Fever was found to be an independent predictor of agitation (OR, 1.86; 95% CI, 1.02–3.49). High fever (>39.3 °C), was associated with a higher possibility for patients to manifest severe agitation (p = 0.046).

Conclusion

Considering the significant adverse consequences of agitation, antipyretic therapy may be recommended for the elderly ICU population, especially when fever is combined with other factors predisposing to agitation or when fever becomes high.

Introduction

Agitation has been identified as a psychomotor disorder and described as a continuum of varying patient behaviours and responses, including disorientation, restlessness, thrashing around in bed, pulling catheters and tubes and over-breathing the ventilator (Cohen et al., 2002). Recent studies have reported agitation to be particularly common in Intensive Care Unit (ICU) patients, with its incidence ranging between 52.0% and 70.8% (Fraser et al., 2000, Jaber et al., 2005). This variation may be partly attributed to differences among studies regarding patient inclusion criteria (i.e. mechanically ventilated or not), to difficulties in the definition and differential diagnosis of agitation and to the use of different scales developed for monitoring agitation (Fraser and Riker, 2001).

Agitated behaviour has been associated with potentially dangerous complications, such as unplanned self-extubation, removal of arterial or venous catheters and increased systemic and myocardial oxygen consumption, as well as with adverse patient outcomes, including prolonged mechanical ventilation and ICU stay and increased nosocomial infection rate (Chevrolet and Jolliet, 2007, Tung et al., 2001). Both pharmacologic agents and physical restraints have been used for treating agitation (Boyer, 2009, Hine, 2007). However, considering that prevention is superior to treatment, identification and timely treatment of factors predisposing to agitation are important. These factors (Cohen et al., 2002) can generally be divided into patient characteristics (high clinical severity and neurological damage), metabolic disorders (acidosis), drugs administered or devices used (nasogastric tube and Foley catheter) and the ICU environment (circadian disruption).

Fever is particularly common in ICU patients and may effect up to 75% of the medical–surgical ICU patients (Circiumaru et al., 1999). According to the findings of studies conducted in ICUs, temperature elevation is independently associated with neuropsychiatric disorders. In the study by Jaber et al. (2005), fever (core temperature >38.3 °C) was the second most important risk factor for the manifestation of agitation [odds ratio (OR), 4.5; 95% confidence interval (CI), 1.8–11.5]. Likewise, Aldemir et al. (2001) found fever to be an independent predictor of delirium (OR, 14.3; 95% CI, 4.1–49.3).

Elderly patients (>65 years) may represent a distinct population for agitation in the ICU, since the prevalence of both cognitive impairment and non-cognitive behavioural symptoms are generally high among them (Lee et al., 2008, Zannino et al., 2004). In addition, elderly patients are particularly susceptible to temperature elevation, thus fever can aggravate any pre-existing mental dysfunction (Plaisance and Mackowiak, 2000). Jaber et al. (2005) found risk for agitation to be 2.21 times higher in the elderly critically ill patients (compared with younger ones). Similarly, in the study of Fraser et al. (2000), agitation was more common in the elderly (76% vs 66% in the younger ones), although no significant age-related difference could be detected. In case fever significantly contributes to agitation, antipyretic therapy may be beneficial for the elderly, either by preventing agitation episodes or by decreasing their duration and severity.

The aim of this study was to investigate the association between fever and agitation in an elderly, mixed ICU population. Differences in agitation severity and duration according to fever characteristics were further investigated.

Section snippets

Study population, setting, and ethical approval

This prospective study was conducted in the 14-bed, medical–surgical ICU of Patras University Hospital, a tertiary care, academic hospital in Patras, Greece. Patients >65 years, who were consecutively admitted in the ICU from October 2005 to September 2006, were included in the study. Patient exclusion criteria were an ICU length of stay <12 h and a level of consciousness impossible to be evaluated. This could be due to either severe neurologic damage (acute brain injury, intracerebral or

Results

Parametric variables are presented as mean ± standard deviation, non-parametric ones are presented as median (interquartile range) and categorical variables are presented as number (%). One hundred sixty-six elderly patients were admitted to the ICU during the study period and 161 of them were eligible for the study. There were 91 (56.5%) male and 99 (61.5%) surgical patients. Median age was 73.0 years (69.0–77.0) and mean APACHE II score was 15.3 ± 4.5 points. Median mechanical ventilation

Discussion

This study focused on the association between fever and agitation among elderly, critically ill patients. Agitation was found to be more commonly manifested in febrile patients, and fever was an independent predictor of agitation when factors identified in previous studies to contribute to agitation were considered. Besides fever, it was important that in agreement with the findings of Jaber et al. (2005), previous history of drug use/alcohol abuse and acidosis were found to be independently

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