Organizational factors associated with target sedation on the first 48 h of mechanical ventilation: an analysis of checklist-ICU database

The burden of oversedation has been recognized for many years [1], even after adjustment for potential confounders. In addition, strategies aiming at light sedation levels have consistently demonstrated efficacy in reducing time on mechanical ventilation, intensive care unit (ICU), and hospital length of stay [2, 3]. More recently, even deep sedation levels on the first 48 h of mechanical ventilation were associated with negative outcomes, including increased mortality [4, 5].

Despite the vast number of studies showing light sedation levels associated with positive outcomes in patients on mechanical ventilation, its adoption is far from being widespread. Observational studies suggest up to two thirds of patients on mechanical ventilation are deeply sedated [6‐10]. In the checklist-ICU study, even if the intervention led to a higher compliance to predefined goals as compared with the control group, only 40.5% of patients on mechanical ventilation in the intervention group achieved the target sedation level [11].

Organizational factors and processes of care are associated with improved outcomes in critically ill patients such as high-intensity staffing ICUs [12, 13], continuity of care [14], multidisciplinary rounds [15], and adoption of protocols [16]. ICU context factors, such as safety culture, lack of leadership, and lack of interprofessional team support, may play a role as barriers to an effective implementation of a bundle of awaking and breathing coordination, delirium, and early mobilization [17]. However, no study evaluated what organizational factors were related to achieving sedation goals.

Therefore, we aimed to identify organizational factors that were associated with moderate to light sedation levels on the first 48 h of mechanical ventilation after ICU admission by performing a secondary analysis of a large quality improvement cluster-randomized RCT [11]. Additionally, we aimed to assess the association of early moderate to light sedation levels with hospital mortality.

Patients on adequate sedation levels were more frequently admitted for acute respiratory failure and had lower SAPS 3 and SOFA scores. Unadjusted ICU and hospital mortality were lower for patients with the target adequate sedation level. ICU and hospital length of stay were increased for patients with inadequate sedation levels (Table 1).

The proportion of patients on adequate sedation levels increased during observation days from 29.9%(CI 95%, 28.7–31.1) on day 2 reaching a maximum of only 45.7%(CI 95%, 42.9–48.5) on day 17 (Fig. 1).

Regarding the organizational factors, having a board-certified intensivist on both the morning and afternoon shifts was the sole factor associated with patients on mechanical ventilation being at a light to moderate sedation level (OR = 2.43; CI 95%, 1.09–5.38) (Table 2). There was no multicollinearity among the included variables (Additional file 1: Table S1).

A light to moderate sedation level on day 2 was associated with reduced hospital mortality when adjusted for SAPS 3 and SOFA (OR = 0.63; CI 95%, 0.55–0.72). The mediation model suggested that an adequate sedation level was significantly associated with hospital mortality (average causal mediation effect: b = − 0.0061; CI 95% − 0.0061 to < − 0.0001), but there was no direct effect of the physician staffing model (average direct effect: b = 0.0226; CI 95% − 0.0043 to 0.05000) on mortality (Additional file 1: Figure S1).

Our study suggested that having a board-certified intensivist on the morning and afternoon shifts was the only organizational factor associated with achieving target sedation levels in patients on mechanical ventilation 48 h after ICU admission. Additionally, we demonstrated that light and moderate sedation levels are associated with reduced hospital mortality. Interestingly, the number of patients on target sedation levels increased as long as ventilation time increased.

Daytime high-intensity staffing is associated with improved outcomes, such as mortality, and reduced time on mechanical ventilation and ICU length of stay [12, 20, 21]. We can postulate that achievement of light sedation levels on the first 48 h of mechanical ventilation may be one possible mechanism of improved outcomes in high-intensity staffing levels, since physician staffing did not have any direct effect on mortality in mediation analysis. Additionally, despite protocols were previously associated with improved outcomes in critically ill patients [16], it seems it is not enough just to have them in an ICU, since sedation protocols did not decrease time on mechanical ventilation in some specific settings [22, 23]. Probably, jointly management by different professionals seems to be of paramount importance for protocols to achieve their goals [16]. Our study suggests that intensivists may have an important role in lighter sedation targets. It is possible that intensivists may be more aware of the importance of light sedation goals than non-intensivists. The presence of more intensivists in an ICU may, hence, ensure that this target will be pursued with more determination. Therefore, a high-intensity staffing model may be part of a system of care, which then leads to improved outcomes [24]. This is an important finding as it represents a potentially modifiable factor. However, the shortage of intensivists in low- and middle-income countries [25, 26] precludes a wider adoption of a daytime high-intensivists staffing model. It is unknown whether other models, such as telemedicine, may increase adherence to lighter sedation levels.

We observed a positive association between early light and moderate sedation levels and reduced mortality, adjusting for patient severity. This association had already been demonstrated in previous studies [7, 8, 27, 28] and confirmed in a meta-analysis [4]. However, this is the largest cohort to show this relation ever. Although not new, these findings reinforce the need to reach light sedation levels from the beginning of mechanical ventilation.

The majority of patients (61.8%) were deeply sedated in the first 48 h of mechanical ventilation in our study. This result is similar to that from other studies that addressed the impact of early sedation on mortality [7, 8], but represents an opportunity for improvement since deep sedation may play a role in the high mortality observed in critically ill patients on mechanical ventilation in Brazil [29]. As expected, a higher proportion of patients were at light and moderate sedation levels as the mechanical ventilation time increased. We believe there are two hypotheses for this finding. First, there is a generalized perception that acute severely ill patients need to be deep sedated, since most studies addressing strategies of light sedation included patients only after 48 h of mechanical ventilation [30, 31], and performing a tracheostomy reduces the use of sedatives [32]. Unfortunately, we did not collect any data on severity on subsequent days after ICU admission neither on tracheostomy in the original study to address these hypotheses.

Our study has some limitations. First, it is a secondary analysis of a study designed to evaluate the effectiveness of a multifaceted quality improvement strategy including a checklist in ICU. Thus, some important data regarding sedation practices, mechanical ventilation, and patients’ severity are missing (for example, type and dosage of sedatives used, more frequent RASS assessments, a daily SOFA, delirium assessment, and number of tracheostomies performed). Second, it was not possible, from our database, to identify if a deep sedation level was secondary to sedatives or to non-modifiable causes, such as an acute encephalopathy. Third, we also do not have data regarding clinical pharmacists, whose interventions on sedation may be associated with decreased mechanical ventilation times [33]. These missing data and other potential confounders may have affected our results. Fourth, all included ICUs are from Brazil. It is widely known that organizational factors and process of care hugely differ worldwide. Although daytime high-intensity staffing may be an outdated problem in high-income countries, only 54% of patients of the present study were admitted to ICUs with board-certified intensivists on the morning and afternoon shifts. Low-income countries have lower percentages of board-certified intensivists in ICU compared to high-income countries [16, 26].

Having board-certified intensivists on the morning and afternoon shifts was associated with an increased number of patients achieving lighter sedation goals. Lighter sedation goals are associated with decreased hospital mortality when adjusted for patients’ severity. Light sedation was more common as patients stay for more days on mechanical ventilation. These findings reinforce the importance of aiming a sedation level targeting an alert and calm patient early on mechanical ventilation and shed light on organizational factors that may increase adherence to this aim.