# Relation of Reported Sedation and Ventilator Weaning Practices to Ventilator Time in Norwegian Intensive Care Units

Authors: Marit Bekkevold; Reidar Kvåle; Guttorm Brattebø
Journal: Journal of Critical Care Medicine
 (2015)

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## Abstract

Background. Guidelines for sedation, ventilator weaning, and delirium screening are helpful to avoid too deep sedation and to identify signs of delirium in the intensive care unit (ICU). Methods. National ICU registry members (n
=
37) were surveyed regarding use of scoring instruments and guidelines for sedation and ventilator weaning, choice of drugs, and daily sedation interruption practices. Results were merged with registry data on ventilator time and length of stay for ICU patients ventilated >24 hours (7.075 ICU stays). Results. Eighty-five percent of the 33 responding ICUs used sedation scales and 39% and 55% had sedation and weaning protocols, respectively. An association was found between using protocols and longer mean ventilator time and mean length of ICU stay. Thirty three percent (11/33) practiced daily sedation interruption. Regular delirium assessment was associated with significantly shorter mean ventilator time and mean length of ICU stay but used by few. Conclusion. More ICUs had guidelines for weaning than for sedation. The ventilator time and length of ICU stay compared well with other studies. Although having guidelines was associated with longer ventilator time and ICU stay, the differences were rather small. Daily sedation interruption was seldom used. Few units used delirium scoring instruments.


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## Body

## 1. Introduction

Respiratory failure is one of the most common reasons for admittance to the intensive care unit (ICU) and such patients are mostly sedated [1]. Continuous intravenous sedation is often used and easy to administer, but both over- and undersedation can result in complications [2]. High doses of sedatives are associated with prolonged ventilation, an increased incidence of ventilator-associated pneumonia, and delirium [3–5]. The trend today goes towards using less sedation but making sure the patient has enough analgesia [6]. Daily sedation interruption can be beneficial, with shorter ventilator times and ICU stays, and reduced mortality [7–9]. Although sedation must be tailored to each patient’s individual needs, wide variation often exists among doctors and nurses in how they actually practice sedation. This can be reduced by using protocols and guidelines. Sedation guidelines have been shown to reduce ventilator time (VT), and protocols can speed up the weaning process [2, 9, 10]. Critically ill patients may also develop delirium, which is associated with severe outcomes [11, 12]. High quality ICU practice includes having validated methods for identification of delirium, using them routinely, and adopting routines for care to minimize delirium incidence [2, 5, 13–15].Norway has roughly 50 somatic hospitals covering 5 million inhabitants. However, many of these are rather small community hospitals without a full-range ICU. The Norwegian Intensive Care Registry (NIR) was established in 1998 as a national medical quality registry. NIR collected data from the 37 member hospitals in 2008 and 2009, and data from these two years were used in this study. Data on Norwegian sedation practices has been published previously [16–20].Our aim was to investigate three factors in Norwegian ICUs reporting to NIR: (1) Whether they have guidelines or not for sedation and ventilator weaning. (2) Whether they practice daily sedation interruption. (3) Whether patients are routinely screened for delirium. We also wanted to investigate whether guideline use in each ICU covaried with reported VT and length of ICU stay (LOS).


## 2. Methods

After receiving approval from the institutional research ethics committee and the NIR board, a questionnaire was sent to the 37 NIR members. In April 2010, the questionnaire was sent to the person in each ICU responsible for reporting to the NIR. They were asked to answer on behalf of their ICU. Some of the questions required the respondents to answer on a general basis for their units; for example, to what extent the various practices were applied, with response options “Rarely,” “Sometimes,” “Often,” or “As a rule.” Nonresponding ICUs received reminders after one month and were subsequently contacted by phone. The registry data were then combined with the questionnaire information, making each unit’s data anonymous prior to the statistical analysis (PASW Statistics 18). Data are presented with both mean and medians to enhance comparison to other studies. Although the data are somewhat skewed,t-tests were used to test for differences in the continuous variables (VT and LOS). In the analysis, the “Rarely” and “Sometimes” responses were grouped together and compared to the combined responses of “Often” and “As a rule.” Differences were considered significant at P
<
0.05.The ICUs were grouped depending on whether they reported using guidelines or not. An ICU stay was defined as a stay where the patient needed more than 24 hours of ventilatory support via a closed system. ICU stays of <24 hours’ duration were excluded, because the effects of sedation and the weaning guidelines were considered minimal for such short stays. Many of these patients may also be noncomplicated postoperative patients, needing ventilation <24 hours. Further, patients who died during their ICU stay were excluded from the analysis because they would not have benefited from either sedation or from weaning guidelines. When patients were transferred to another hospital, the data from the ICU where they were transferred from was excluded to avoid double entries. Illness severity was calculated using the simplified acute physiology score (SAPS II) [21]. We combined the NIR data available from the responding units for both 2008 and 2009 to make the analysis more robust. For a small number of ICU stays, a complete set of data were not provided for all of the predefined NIR variables due to incomplete reporting, but all available data was used for each analysis.


## 3. Results

We received responses from 33 (89%) of the 37 ICUs. The NIR registered a total of 26,781 ICU stays over the two-year period. Patients under the age of 18 years amounted 6.5% of the stays. Descriptive data are given in Table1. The mean SAPSII scores for patients on ventilator less than 24 hours were lower than for those needing ventilation for more than 24 hours (31.9 versus 43.0). The ICU mortality of patients requiring more than 24 hours’ ventilation was 18% (7.075 ICU stays) and for the patients requiring less than 24 hours’ ventilation was 21% (6.419 ICU stays).Table 1
Characteristics of ICU stays reported to the Norwegian Intensive Care Registry  (NIR) in 2008 and 2009.
Variable
Sedation guidelines
No sedation guidelines
Weaning protocols
No weaning protocols
Total number of ICU stays
26.781
9503
12093
12394
9202
Number of ICU stays on ventilator
13494  (50%)
Number of ICU stays on ventilator for more than 24 h
7.075  (26%)
3311
3764
4008
3067
Number of ICU stays on ventilator for more than 24 h resulting in death in the ICU
1.253  (18%)
627
579
768
438
Number of ICU stays resulting in transfer to other hospitals or missing
543
Total number of stays included in the analysis
5.279
Mean ventilator time in days for those on ventilator <24 h  (range)Median  (IQR)
0.4  (0.1–0.9)0.40  (0.2–0.6)
0.4  (0.1–0.9)0.40  (0.2–0.6)
0.4  (0.1–0.9)0.40  (0.2–0.7)
0.4  (0.1–0.9)0.40  (0.2–0.6)
0.4  (0.1–0.9)0.40  (0.2–0.7)
Mean ventilator time in days for those on ventilator >24 h  (range)Median  (IQR)
7.0  (1.0–118.1)3.9  (1.8–8.8)
7.9  (1.0–73.2)4.6  (2.2–9.9)
7.0  (1.1–118.1)4.0  (2.0–8.6)
7.8  (1.0–93.7)4.6  (2.1–9.8)
6.9  (1.1–118.1)4.0  (2.0–8.5)
Mean length of ICU stay  (days) for those on ventilator <24 h  (range)Median  (IQR)
1.6  (0.1–55.4)0.9  (0.6–1.8)
1.5  (0.1–31.8)0.9  (0.5–1.8)
1.6  (0.1–55.4)0.9  (0.6–1.7)
1.6  (0.1–55.4)1.0  (0.5–1.9)
1.5  (0.1–30.9)0.9  (0.6–1.6)
Mean length of ICU stay  (days) for those on ventilator >24 h  (range)Median  (IQR)
9.1  (1.0–118.1)5.9  (2.9–11.7)
9.4  (1.0–80.0)5.9  (3.0–11.9)
8.7  (1.0–118.1)5.5  (2.7–11.0)
9.6  (1.0–100.0)6.1  (3.0–12.1)
8.3  (1.0–118.1)5.1  (2.6–10.4)
Mean SAPS II score for those on ventilator <24 h, mean  (range)Median  (IQR)
31.9  (0–111)32.0  (12–47)
38.4  (0–111)38.0  (25–52)
25.9  (0–110)26.0  (0–43)
38.3  (0–111)37.0  (25–51)
23.7  (0–110)22.0  (0–41)
Mean SAPS II score for those on ventilator >24 h, mean  (range)Median  (IQR)
43.0  (4.0–114.0)42.0  (32.0–53.0)
46.2  (0–114)45.0  (34–57)
44.7  (0–113)43.0  (32–50)
45.8  (0–114)44.0  (37–57)
45.0  (0–113)44.0  (32–56)
Mean patient age in years for those on ventilator <24 hMedian  (IQR)
59.564.7  (48.3–76.6)
60.065.3  (46.5–77.7)
58.864.1  (49.3–75.2)
60.865.8  (48.7–77.5)
57.863.6  (47.1–75.1)
Mean patient age in years for those on ventilator  >24 hMedian  (IQR)
56.662.0  (46.7–71.2)
59.463.8  (50.0–73.6)
57.262.7  (48.0–73.7)
60.164.2  (51.1–74.0)
55.862.1  (46.2–72.9)
Mean, range, interquartile range  (IQR), and medians are given for comparisons.
ICU: intensive care unit.Eighty-five percent of the units stated that they used a sedation scoring tool and 15% did not. The Motor Activity Assessment Scale (MAAS) was most frequently used (82%), and the remaining ICUs (18%) reported using the Richmond Agitation Sedation Scale (RASS) [22, 23]. Only 39% of the units reported having sedation guidelines and the use of these guidelines is given in Table 2. The rest of the responding units stated they did not have sedation guidelines. Surprisingly, we found significant higher mean VT and mean LOS in the units that reported using sedation guidelines than in those that did not (Table 3). Fifty-five percent (18/33) of the units reported they had protocols for ventilator weaning (Table 2). Mean VT and mean LOS were significantly higher for the ICUs reporting that they had weaning protocols (Table 4). Interestingly, we also found that mean VT was significantly longer for the ICUs reporting use of weaning guidelines “Often” or “As a rule,” whereas the mean LOS was significantly shorter (Table 5). Only eight of the responding units reported having changed their routines during the last two years.Table 2
Reported use of sedation guidelines, weaning protocols, and sedation interruption in Norwegian ICUs.
“Rarely”
“Sometimes”
“Often”
“As a rule”
How often are the sedation guidelines used? (N
=
13)
15% (2)
23% (3)
31% (4)
31% (4)
How often are the weaning protocols used? (N
=
18)
28% (5)
33% (6)
33% (6)
6% (1)
Can the nurses adjust the sedation without consulting a physician?
∗ (N
=
33)
0% (0)
15% (5)
49% (16)
36% (12)
Can the nurses adjust the sedation without consulting a physician during weaning?
∗ (N
=
33)
3% (1)
21% (7)
46% (15)
30% (10)
Use of daily sedation interruption?
∗ (N
=
33)
33% (11)
33% (11)
25% (8)
9% (3)
∗
All units, including those reporting no guidelines or protocols, answered this question.Table 3
Effect of reporting having sedation guidelines on ventilator time (VT) and length of ICU stay (LOS).
ICUs (N)
Sedation guidelines
Number of stays
Median (days)
Mean (days)
Difference (days)
Time on ventilator
13
Yes
2,529
4.6
7.9
Mean difference = 0.995% CI = 0.5–1.4, P
<
0.01
20
No
2,750
4.0
7.0
Length of ICU stay
13
Yes
2,529
5.9
9.4
Mean difference = 0.795% CI = 0.4–1.4, P
<
0.01
20
No
2,750
5.5
8.7
Stays resulting in death in the ICU, transfer, or ventilator time <24 hours were excluded.Table 4
Effect of reporting having weaning protocols on ventilator time and length of ICU stay.
ICUs (N)
Weaning protocols
Number of stays
Median (days)
Mean (days)
Difference (days)
Time on ventilator
18
Yes
3,007
4.6
7.8
Mean difference = 0.995% CI = 0.6–1.5, P
<
0.01
15
No
2,272
4.0
6.9
Length of ICU stay
18
Yes
3,007
6.1
9.6
Mean difference = 1.395% CI = 1.0–2.0, P
<
0.01
15
No
2,272
5.1
8.3
Stays resulting in death in the ICU, transfer, or ventilator time <24 hours were excluded.Table 5
Effect of reporting use of sedation guidelines, weaning protocols, and delirium evaluations on ventilator time and length of ICU stay.
“How often are the guidelines or protocols used?”
Number  of stays
Mean time on ventilator, days (median)
Mean difference in days with corresponding 95% confidence intervals
Mean length  of ICU stay, days (median)
Mean difference in days with corresponding 95% confidence intervals
Sedation guidelines
“Rarely” or “Sometimes”
600
7.0 (4.0)
0.7
10.0 (6.6)
0.6
“Often” or “As a rule”
1,929
7.7 (4.5)
95% CI = 0.1–1.4,P
=
0.09
9.4 (6.2)
95% CI = 0.4–1.4,P
=
0.25
Weaning protocols
“Rarely” or “Sometimes”
1,072
6.9 (3.5)
0.8
10.5 (6.8)
1.1
“Often” or “As a rule”
1,935
7.7 (4.8)
95% CI = 0.2–1.4,P
=
0.01
9.4 (6.2)
95% CI = 0.3–1.8,P
<
0.01
Evaluation of delirium
“Rarely” or “Sometimes”
3,652
7.3 (4.3)
1.1
9.9 (6.5)
2.5
“Often” or “As a rule”
1,565
6.2 (3.4)
95% CI = 0.6–1.6,P
<
0.01
7.4 (4.4)
95% CI = 2.0–3.0,P
<
0.01
Stays resulting in death in the ICU, transfer, or ventilator time <24 hours were excluded.Only a third of the units reported practicing daily sedation interruption “Often” or “As a rule” (Table2). No significant difference in the mean VT and mean LOS was found between these and the remaining hospitals.The choice of type of sedative agent used was reported to be determined mainly by the expected duration of sedation. For sedation expected to last more than 24 hours, 85% reported midazolam as their primary sedative agent, and 79% used fentanyl as the first analgesic. After ventilator weaning was initiated 55% of the units changed pharmacological agents “Often” or “As a rule.” Propofol (76%) and fentanyl (55%) were the most frequently used during the weaning period. Remifentanil was more often used for analgesia during weaning (21%) than during “regular” mechanical ventilation (3%).Most units (91%) reported “Rarely” using continuous subcutaneous analgesic infusion in sedated patients. Seventy-nine percent of units reported that they “Rarely” assessed patients for signs of delirium, and only 15% employed a specific scoring tool for this. When comparing the ICUs that reported evaluating patients for delirium “Often” or “As a rule” to the other units, a significant reduction in both mean VT and mean LOS was found (Table5).


## 4. Discussion

Of the responding ICUs 85% reported using sedation scales, while 39% had sedation guidelines and 55% had weaning protocols. Interestingly, our data indicate that the units which reported using sedation guidelines and ventilator weaning protocols had significantly longer mean VT and mean LOS.Our data are based on a large number of ICU stays, and the patients’ age and illness severity are in accordance with other studies [24–26]. The proportion of ICU stays in which mechanical ventilation was needed for more than 24 hours (26%) reflects the fact that most ICUs in Norway are rather small, with a mix of surgical and medical patients. This is also seen in the difference in SAPSII scores between those requiring ventilator for more than 24 hours compared to those with shorter ventilator times (Table 1). The reported ICU mortality is also comparable to that of other studies [8, 24, 26]. As expected the mortality among those on a ventilator for less than 24 hours was higher (21%) than among those on ventilator for more than 24 hours (18%), since the most physiological deranged patients expire early.Continuous intravenous sedation, commonly practiced in Norway, may be associated with longer VT [27]. Midazolam and fentanyl were the most frequently used. The use of both fentanyl and midazolam (both metabolized by the same pathway) may have influenced drug levels and hence caused excessive sedation [28]. Adjusting analgesic treatment may also correlate with VT [29]. We did not ask the ICUs how they screen for pain or adjust analgesia. Only one-third of the units practiced daily sedation interruption and few reported using a delirium assessment instrument.Most ICUs reported using a specific sedation scoring tool, as reported previously [17, 18]. This compares well to other European studies [23, 30–32]. More use of sedation and pain assessment tools in the Nordic countries than in non-Nordic countries has been reported [33]. Use of guidelines is linked to shorter times on mechanical ventilation, but only 39% of the ICUs in this study reported having such guidelines, as previously reported [17, 18]. We had expected a higher proportion, partly as a result of the national ICU collaboration which strongly recommended the use of sedation guidelines [16]. Two-thirds of units that reported having sedation guidelines answered they were using them “Often” or “As a rule.” It is well known that just having a guideline is not the same as using it in every patient [34]. We did not ask the ICUs how deeply sedated their patients were.The modern approach to ICU care is team oriented where doctors and nurses work closely together. However, it can vary how the nurses may adjust therapies. Most ICUs reported that nurses were allowed to adjust the sedation “Often” or “As a rule.” All the ICUs were asked this question, regardless whether they reported having guidelines. We did not ask the ICUs reporting no guidelines whether they had specific nurse instructions. Having to call a doctor for every sedation adjustment could result in fewer adjustments and, consequently, deeper sedation.Nurses’ attitudes impact sedation, and addressing attitudes may be necessary to succeed in changing practices [35]. Gaining acceptance and support for new procedures is important to change behaviour [34]. In a study from 2013, nurses from the Nordic countries reported more interprofessionally collaboration in decision-making on sedation than those from non-Nordic countries [33].We found that having guidelines for ventilator weaning was more common than for sedation. More than half of the ICUs reported having ventilator weaning protocols, an important change from 2004, when only 21% had such protocols [17].Surprisingly, we found that ICUs reporting that they had sedation guidelines or weaning protocols seemed to be associated with both longer mean VT and mean LOS. However, the magnitude of difference was small (0.9–1.5 days). When the analysis was repeated, including only patients requiring more than 48 or 72 hours of ventilation, the associations were still significant and of the same magnitude. On the other hand, the median VT of 3.9 days for all ICU stays requiring more than 24 hours of ventilation, as well as the median LOS of 5.9 days, is lower than what has been reported by others [9, 24, 25]. The use of step-down units is uncommon in Norway, and NIR does not have data on when a patient is considered ready to be discharged from the ICU to another ward, only when patients are discharged.One reason for the unexpected association may be that sedation and weaning guidelines are most effective when used consistently, and daily life in an ICU may be different from the environment during a study. Some patients may be treated strictly according to the guidelines, whereas others are not [36]. When a department participates in a project of some kind, the focus is on the intervention, resulting in stricter adherence to existing treatment protocols [37, 38].Translating the best available scientific knowledge regarding correct treatment into daily clinical practice is difficult [2, 38–40]. The interaction of guidelines for sedation and weaning is not fully understood, and whether a specific patient or patient group receives more or less benefit from each of the guidelines is unknown.Merging data from many different ICUs should reduce the likelihood of case-mix differences between units with guidelines and units without guidelines but cannot be ruled out as a contributing factor to the associations found.Since coma and delirium appear to be independent predictors of hospital stay, hospital costs, and mortality, one would expect that most ICUs regularly screened their patients for delirium [5, 12–14]. However, only 15% reported using a specific delirium scoring instrument. Reluctance to routinely monitoring delirium has been blamed on lack of familiarity with the assessment tools and problems with their implementation [41, 42]. This is an area for improvement. ICU-acquired neuropathy affects VT, LOS, and outcome after critical illness [43]. We did not ask the ICUs if they screen for critical illness neuropathy. This also could have affected the results.As expected, the results show variation in ICU sedation practice. Daily sedation interruption reduces duration of controlled ventilation and mortality [2, 8, 9, 36]. Few ICUs practiced this “Often” or “As a rule,” though higher than 7% as previously reported [17]. In the UK survey, 78% of the responding ICUs stated that they practiced this [30]. We found no difference between hospitals with sedation or weaning guidelines and those without guidelines regarding daily sedation interruption.This study can be viewed as a type of ecological study looking at the association between different variables, not based on individual data. Such studies can be used as a basis for hypothesising about associations but not for identifying causal relationships [38]. A weakness of this study is the lack of data on the individual patients. On the other hand, data are based on a large number of ICU stays, and we do believe that the responses reflect Norwegian ICUs’ use of these guidelines.Another issue is that the respondent had to judge their own unit, but these persons were those who regularly report data to the NIR, so they should be familiar with their departments’ practice. Because the NIR covers most ICUs in Norway, and the high response rate, we assume that the results reflected Norwegian ICU practice. Yet another weakness is that the results are based on a questionnaire and not on direct observation or other types of auditing guideline adherence. Therefore, we do not know for certain to what extent available guidelines and protocols actually are used in daily practice. Lastly, the observed difference between departments may also be based more on other local treatment traditions than merely having guidelines. We did not ask on which patients the guidelines were used, that is, only used on the most critically ill. Parametric tests were employed although data were skewed. However, when applying nonparametric testing, the results showed the same differences. Test results are reported as means because this is often used by others.


## 5. Conclusions

Most Norwegian ICUs reported using some sort of sedation scoring tool, but less than half of them had sedation guidelines. One out of two had weaning protocols. Daily sedation interruption is not common practice. The units reporting having such guidelines and protocols also seemed to have patients on mechanical ventilation for a longer time, and longer ICU stays. The observed associations are difficult to explain and should not be taken as an argument against sedation or weaning guidelines. The use of guidelines for ventilator weaning has increased, but delirium monitoring is not common practice. Few units reported using a specific delirium scoring tool. However, reporting regularly assessing ICU patients for delirium was associated with a shorter mean VT and ICU stay.Based on our findings, there seems still to be room for improving sedation, weaning, and delirium monitoring in Norwegian ICUs.



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