Characteristics and outcomes of trauma patients with unplanned intensive care unit admissions: Bounce backs and upgrades comparison

Abstract

BACKGROUND

The need for an emergency upgrade of a hospitalized trauma patient from the floor to the trauma intensive care unit (ICU) is an unanticipated event with possible life-threatening consequences. Unplanned ICU admissions are associated with increased morbidity and mortality and are an indicator of trauma service quality. Two different types of unplanned ICU admissions include upgrades (patients admitted to the floor then moved to the ICU) and bounce backs (patients admitted to the ICU, discharged to the floor, and then readmitted to the ICU). Previous studies have shown that geriatric trauma patients are at higher risk for unfavorable outcomes.

AIM

To analyze the characteristics, management and outcomes of trauma patients who had an unplanned ICU admission during their hospitalization.

METHODS

This institutional review board approved, retrospective cohort study examined 203 adult trauma patients with unplanned ICU admission at an urban level 1 trauma center over a six-year period (2017-2023). This included 134 upgrades and 69 bounce backs. Analyzed variables included: (1) Age; (2) Sex; (3) Comorbidities; (4) Mechanism of injury (MOI); (5) Injury severity score (ISS); (6) Glasgow Coma Scale (GCS); (7) Type of injury; (8) Transfusions; (9) Consultations; (10) Timing and reason for unplanned admission; (11) Intubations; (12) Surgical interventions; (13) ICU and hospital lengths of stay; and (14) Mortality.

RESULTS

Unplanned ICU admissions comprised 4.2% of total ICU admissions. Main MOI was falls. Mean age was 70.7 years, ISS was 12.8 and GCS was 13.9. Main injuries were traumatic brain injury (37.4%) and thoracic injury (21.7%), and main reason for unplanned ICU admission was respiratory complication (39.4%). The 47.3% underwent a surgical procedure and 46.8% were intubated. Average timing for unplanned ICU admission was 2.9 days. Bounce backs occurred half as often as upgrades, however had higher rates of transfusions (63.8% vs 40.3%, P = 0.002), consultations (4.8 vs 3.0, P < 0.001), intubations (63.8% vs 38.1%%, P = 0.001), longer ICU lengths of stay (13.2 days vs 6.4 days, P < 0.001) and hospital lengths of stay (26.7 days vs 13.0 days, P < 0.001). Mortality was 25.6% among unplanned ICU admissions, 31.9% among geriatric unplanned ICU admissions and 11.9% among all trauma ICU patients.

CONCLUSION

Unplanned ICU admissions constituted 4.2% of total ICU admissions. Respiratory complications were the main cause of unplanned ICU admissions. Bounce backs occurred half as often as upgrades, but were associated with worse outcomes.

Core Tip: Unplanned intensive care unit (ICU) admissions constituted 4.2% of all trauma ICU admissions. Although upgrades happened more often, bounce backs were associated with worse outcomes, particularly in geriatric patients. Traumatic brain injuries and thoracic injuries together accounted for more than half of the injuries in trauma patients who required an unplanned ICU admission and this tendency was more pronounced in bounce backs and in geriatric patients. Three quarters of unplanned ICU admissions occurred within the first 72 hours of hospitalization. The main reasons for unplanned ICU admissions were respiratory complications. Patients with unplanned ICU admissions had twice the mortality of general trauma ICU patients.

INTRODUCTION

Studies on unplanned intensive care unit (ICU) admissions have been published before and addressed primarily medical and surgical ICU, while studies related to unplanned ICU admissions in trauma patients remain scarce[1-5]. Unplanned admissions to the ICU foreshadow serious clinical implications, including increased lengths of stay, increased hospital costs and higher mortality[4,6-8]. When it comes to the definitions, unplanned ICU admissions are typically divided into two different groups: (1) Upgrades; and (2) Bounce backs. Patients transferred to the ICU after initial admission to the floor are termed upgrades[9]. Meanwhile, patients readmitted to an ICU during the same hospitalization following transfer to a lower level of care (step down unit or floor) are termed either bounce backs, ICU re-admissions, returns, return transfers or rebounds[2,10,11]. Unplanned ICU admissions are considered a quality metric indicator by the American College of Surgeons Trauma Quality Improvement Program[4]. Traditionally, there is more focus on bounce backs, as they have been considered a potentially preventable event and therefore a target for improvements[6,7,10,12,13]. Moreover, the rates and definitions of unplanned ICU admissions in trauma patients vary widely and continue to be a point of discussion[1,2,4,5,8].

The goal of this study was to analyze the characteristics, management and outcomes of trauma patients who had an unplanned ICU admission during their hospitalization. Particular focus was on the comparison of upgrades and bounce backs and of geriatric and non-geriatric patients.

MATERIALS AND METHODS

This institutional review board approved, retrospective cohort study was granted a waiver of informed consent and included 4791 adult trauma patients who were admitted to the trauma ICU of an urban level 1 Trauma Center between January 2017 and May 2023. Our 14-bed trauma ICU unit has a nurse to patient ratio of 1:2 or 1:1 for higher acuity, critically injured patients. Unplanned ICU admissions were observed in 203 trauma patients. Patients who were under 18 years old, died on admission, or who did not require a trauma ICU admission were excluded from the study. Analyzed variables included: (1) Age; (2) Sex; (3) Comorbidities; (4) Mechanism of injury (MOI); (5) Injury type; (6) Injury severity score (ISS); (7) Glasgow Coma Scale (GCS); (8) Blood transfusions; (9) Number of consultations; (10) Rate of surgical interventions; (11) Reasons for unplanned ICU admissions; (12) Timing of unplanned ICU admission; (13) Respiratory complications; (14) Mechanical ventilation requirements; (15) ICU length of stay; (16) Hospital length of stay; and (17) Mortality.

Patients with unplanned ICU admissions were either upgraded (134 patients) or readmitted (69 patients) to the ICU during their hospitalization. These two definitively different groups of patients were compared. To ensure comparability in the severity of trauma between the groups, propensity score matching by ISS was done, which resulted in 61 pairs (61 upgrades and 61 bounce backs) for comparison. Taking into account the known serious consequences of geriatric trauma, a further analysis of the geriatric population was performed where 141 geriatric patients with unplanned ICU admissions were compared to 62 non-geriatric patients with unplanned ICU admissions. We also analyzed 72 severely injured patients with ISS ≥ 16. Multivariate analysis of the predictors of respiratory complications was performed due to the high prevalence of respiratory complications among the study population. The flow chart of the study is presented in Figure 1.

Figure 1.

Study flow chart. ICU: Intensive care unit; ISS: Injury severity score.

Definitions

Unplanned ICU admissions were characterized as either upgrades or bounce backs. Upgrades were defined as the initial admission of a trauma patient to the floor and an unplanned upgrade to the ICU during the same hospital stay. Bounce backs were defined as an initial admission of a trauma patient to the ICU, followed by a downgrade to the floor with subsequent re-admission to the ICU. These definitions are presented in Figure 2 and are based on the current National Trauma Data Standard Dictionary[9].

Figure 2.

Upgrades and bounce backs definitions. ICU: Intensive care unit.

Severely injured patients were defined as having ISS ≥ 16[14,15]. Mortality was defined as an in-hospital mortality or a hospice discharge[16,17]. Geriatric patients were defined as ≥ 65 years old[18,19]. Indicative variables were identified via international classification of diseases-10 codes and extracted from patient’s electronic medical records.

Statistical analysis

Statistical analysis was performed using IBM Statistical Package for the Social Sciences Statistics software version 23.0 (IBM, Armonk, New York). Propensity score matching was done without replacement, with a 0.2 caliper, and a randomized order of patients while drawing matches, which resulted in a one-to-one, paired selection. Propensity score matching was used to ensure that the injury severity and number of patients was comparable in the groups of upgrades and bounce backs to determine differences in outcomes. The analyses included group characteristics and bivariate correlation comparisons. Categorical variables were analyzed with χ² tests. Variable means were analyzed using independent samples t tests and Mann Whitney-U test based on adequate sample sizes and normal distribution. Statistical significance was assumed when the calculated P value was below 0.05. Analysis also included the use of multivariable logistic regression to determine the predictors of respiratory complications. Multivariable logistic regression is one of the best statistical tools to test which patient injury characteristics can be independent predictors for later complications or outcomes.

RESULTS

Unplanned ICU admissions constituted 4.2% of all trauma ICU admissions (203/4791). Characteristics of 203 patients with unplanned ICU admissions are presented in Table 1. The mean age was 70.7 years, two thirds were male, the main MOI was falls, mean ISS was 12.8, mean GCS was 13.9, 35.5% had ISS ≥ 16, the mean time between the floor admission and unplanned ICU admission was 2.9 days and mortality was 25.6%. Distribution of the main injuries among patients with unplanned ICU admissions is depicted in Figure 3. The main injury was traumatic brain injury (TBI) followed by chest trauma. The reasons for unplanned ICU admissions are presented in Figure 4, with respiratory insufficiency being the most common.

Table 1.

General characteristics of patients with unplanned intensive care unit admissions, n (%)

Variable	ICU (n = 203)
Age (years), mean (SD)	70.7 (19.9)
Geriatric	141 (69.5)
Sex (male/female)	138 (68.0)/65 (32.0)
Comorbidities	186 (91.6)
Mechanism of injury	-
Fall	139 (68.5)
Motor vehicle	59 (29.1)
Other (assault, accident, and burn)	5 (2.5)
Glasgow Coma Scale, mean (SD) (range)	13.9 (2.7) (3-15)
ISS, mean (SD) (range)	12.8 (7.8) (1-38)
ISS ≥ 16	72 (35.5)
Upgrade/bounce back	134 (66.0)/69 (34.0)
Main injury	-
Head-traumatic brain injury	76 (37.4)
Thorax	44 (21.7)
Spine	26 (12.8)
Hip/pelvis	22 (10.8)
Abdominal	11 (5.4)
Extremities	7 (3.4)
Facial	8 (3.9)
Cardiac	6 (3.0)
Pulmonary contusion	14 (6.9)
Pneumothorax	18 (8.9)
Hemothorax	26 (12.8)
Pneumohemothorax	11 (5.4)
Any blood transfusion	98 (48.3)
Any surgical procedure	96 (47.3)
Number of consultations, mean (SD)	3.6 (1.9)
Mechanical ventilation requirement	95 (46.8)
Endotracheal intubation	94 (46.3)
Tracheostomy	14 (6.9)
ICU length of stay (days), mean (SD)	8.7 (12.5)
Hospital length of stay (days), mean (SD)	17.6 (23.8)
Mortality	52 (25.6)
Time: Floor-ICU admission (days), mean (SD)	2.9 (5.4)

ICU: Intensive care unit; ISS: Injury severity score.

Figure 3.

Distribution of main injuries among patients with unplanned intensive care unit admissions.

Figure 4.

Reasons for unplanned intensive care unit admissions. GI: Gastrointestinal.

Of all unplanned ICU admissions, 66% were upgrades and 34% were bounce backs. The comparison between upgrades and bounce backs is presented in Table 2. In general, bounce backs were more severely injured and required more treatment efforts. To account for differences in the trauma severity between the upgrades and bounce backs, patients were propensity score matched by ISS. The comparison between propensity score matched patients is presented in Table 3. After propensity score matching, bounce backs required more transfusions, consultations, intubations and stayed in the ICU and hospital longer.

Table 2.

Characteristics comparison of upgrades and bounce backs, n (%)

Variable	Upgrades (n = 134)	Bounce backs (n = 69)	P value
Age (years) (mean)	72.4	67.5	0.1
Geriatric	99 (73.9)	42 (60.9)	0.1
Sex (male/female)	86 (64.2)/48 (35.8)	52 (75.4)/17 (24.6)	0.1
Comorbidities	126 (94.0)	60 (87.0)	0.1
Mechanism of injury	-	-	0.2
Fall	96 (71.6)	43 (62.3)	-
Motor vehicle	34 (25.4)	25 (36.2)	-
Other (assault, accident, and burn)	4 (3.0)	1 (1.4)	-
Glasgow Coma Scale (mean)	14.6	12.4	< 0.001a
ISS (mean)	11.2	15.8	< 0.001a
ISS ≥ 16	37 (27.6)	35 (50.7)	0.001a
Main injury	-	-	0.003a
Head-traumatic brain injury	42 (31.3)	34 (49.3)	-
Thorax	25 (18.7)	19 (27.5)	-
Spine	23 (17.2)	3 (4.3)	-
Hip/pelvis	17 (12.7)	5 (7.2)	-
Abdominal	5 (3.7)	6 (8.7)	-
Extremities	7 (5.2)	0 (0.0)	-
Facial	8 (6.0)	0 (0.0)	-
Cardiac	5 (3.7)	1 (1.4)	-
Pulmonary contusion	5 (3.7)	9 (13.0)	0.01a
Pneumothorax	7 (5.2)	11 (15.9)	0.01a
Hemothorax	12 (9.0)	14 (20.3)	0.02a
Pneumohemothorax	4 (3.0)	7 (10.1)	0.03a
Any blood transfusion	54 (40.3)	44 (63.8)	0.002a
Any surgical procedure	60 (44.8)	36 (52.2)	0.3
Number of consultations (mean)	3.0	4.8	< 0.001a
Mechanical ventilation requirement	51 (38.1)	44 (63.8)	0.001a
Endotracheal intubation	50 (37.3)	44 (63.8)	< 0.001a
Tracheostomy	6 (4.5)	8 (11.6)	0.1
ICU length of stay (days) (mean)	6.4	13.2	< 0.001a
Hospital Length of Stay (days) (mean)	13.0	26.7	< 0.001a
Mortality	28 (20.9)	24 (34.8)	0.03a
Time: Floor-ICU admission (days) (mean)	2.0	4.5	< 0.001a

^aDenotes a statistically significant difference (P < 0.05).

ICU: Intensive care unit; ISS: Injury severity score.

Table 3.

Characteristics comparison of upgrades and bounce backs propensity score matched by injury severity score, n (%)

Variable	Upgrades (n = 61)	Bounce backs (n = 61)	P value
Age (years) (mean)	74.8	68.7	0.04a
Geriatric	47 (77.0)	39 (63.9)	0.1
Sex (male/female)	41 (67.2)/20 (32.8)	45 (73.8)/16 (26.2)	0.4
Comorbidities	57 (93.4)	55 (90.2)	0.5
Mechanism of injury	-	-	0.9
Fall	41 (67.2)	40 (65.6)	-
Motor vehicle	19 (31.1)	20 (32.8)	-
Other (assault, accident, and burn)	1 (1.6)	1 (1.6)	-
Glasgow Coma Scale (mean)	14.7	12.8	< 0.001a
ISS (mean)	13.9	13.8	0.5
ISS ≥ 16	27 (44.3)	27 (44.3)	1.0
Main injury	-	-	0.2
Head-traumatic brain injury	23 (37.7)	29 (47.5)	-
Thorax	12 (19.7)	19 (31.1)	-
Spine	7 (11.5)	3 (4.9)	-
Hip/pelvis	9 (14.8)	4 (6.6)	-
Abdominal	3 (4.9)	4 (6.6)	-
Extremities	2 (3.3)	0 (0.0)	-
Facial	3 (4.9)	0 (0.0)	-
Cardiac	1 (1.6)	1 (1.6)	-
Pulmonary contusion	3 (4.9)	7 (11.5)	0.2
Pneumothorax	2 (3.3)	9 (14.8)	0.03a
Hemothorax	6 (9.8)	14 (23.0)	0.1
Pneumohemothorax	2 (3.3)	7 (11.5)	0.1
Any blood transfusion	26 (42.6)	38 (62.3)	0.03a
Any surgical procedure	28 (45.9)	30 (49.2)	0.7
Number of consultations (mean)	3.1	4.6	< 0.001a
Mechanical ventilation requirement	25 (41.0)	38 (62.3)	0.02a
Endotracheal intubation	25 (41.0)	38 (62.3)	0.02a
Tracheostomy	5 (8.2)	6 (9.8)	0.8
ICU length of stay (days) (mean)	6.1	11.3	< 0.001a
Hospital length of stay (days) (mean)	12.5	21.7	< 0.001a
Mortality	16 (26.2)	22 (36.1)	0.2
Time: Floor-ICU admission (days) (mean)	2.0	4.4	0.003a

^aDenotes a statistically significant difference (P < 0.05).

ICU: Intensive care unit; ISS: Injury severity score.

The timing of unplanned ICU admission of propensity score matched upgrades and bounce backs is presented in Figure 5. Majority of upgrades happened within the first 72 hours of admissions to the floor.

Figure 5.

Distribution of timing from the floor to the intensive care unit admission in propensity score matched upgrades and bounce backs.

The comparison of geriatric and non-geriatric patients with unplanned ICU admissions is presented in Table 4. Even being similarly injured, geriatric patients had a higher mortality. The distribution of the timing of the unplanned ICU admission in geriatric and non-geriatric patients is presented in Figure 6, and followed a similar trend.

Table 4.

Characteristics comparison of geriatric and non-geriatric patients with unplanned intensive care unit admissions, n (%)

Variable	Geriatric (n = 141)	Non-geriatric (n = 62)	P value
Age (years) (mean)	81.8	45.5	< 0.001a
Sex (male/female)	89 (63.1)/52 (36.9)	49 (79.0)/13 (21.0)	0.03a
Comorbidities	139 (98.6)	47 (75.8)	< 0.001a
Mechanism of injury	-	-	< 0.001a
Fall	114 (80.9)	25 (40.3)	-
Motor vehicle	25 (17.7)	34 (54.8)	-
Other (assault, accident, and burn)	2 (1.4)	3 (4.8)	-
Glasgow Coma Scale	14.4	12.6	0.1
ISS (mean)	12.4	13.6	0.4
ISS ≥ 16	46 (32.6)	26 (41.9)	0.2
Upgrade/bounce back	99 (70.2)/42 (29.8)	35 (56.5)/27 (44.5)	0.1
Main injury-admission	-	-	0.005a
Head-traumatic brain injury	56 (39.7)	20 (32.3)	-
Thorax	31 (22.0)	13 (21.0)	-
Spine	22 (15.6)	4 (6.5)	-
Hip/pelvis	14 (9.9)	8 (12.9)	-
Abdominal	2 (1.4)	9 (14.5)	-
Extremities	4 (2.8)	3 (4.8)	-
Facial	4 (2.8)	4 (6.5)	-
Cardiac	6 (4.3)	0 (0.0)	-
Pulmonary contusion	7 (5.0)	7 (11.3)	0.1
Pneumothorax	11 (7.8)	7 (11.3)	0.4
Hemothorax	22 (15.6)	4 (6.5)	0.1
Pneumohemothorax	8 (5.7)	3 (4.8)	0.8
Any blood transfusion	67 (47.5)	31 (50.0)	0.7
Any surgical procedure	52 (36.9)	44 (71.0)	< 0.001a
Number of consultations (mean)	3.5	3.9	0.4
Mechanical ventilation requirement	52 (36.9)	43 (69.4)	< 0.001a
Endotracheal intubation	51 (36.2)	43 (69.4)	< 0.001a
Tracheostomy	7 (5.0)	7 (11.3)	0.1
ICU length of stay (days) (mean)	6.8	13.1	0.02a
Hospital length of stay (days) (mean)	13.1	27.9	< 0.001a
Mortality	45 (31.9)	7 (11.3)	0.002a
Time: Floor-ICU admission (days) (mean)	2.1	4.7	0.2

^aDenotes a statistically significant difference (P < 0.05).

ICU: Intensive care unit; ISS: Injury severity score.

Figure 6.

Distribution of timing from the floor to the intensive care unit admission in all, geriatric and non-geriatric patients. ICU: Intensive care unit.

Of 203 patients with unplanned ICU admissions, 80 (39.4%) patients were admitted for respiratory complications, which included 45 upgrades and 35 bounce backs. General patient characteristics, injury characteristics and interventions in 80 patients with unplanned ICU admissions for respiratory complications are presented in Table 5. In total, 81 respiratory events occurred among the 80 patients, which are all presented in Figure 7. Multivariable analysis showed that the only independent significant predictor for respiratory insufficiency leading to an unplanned ICU admission was the presence of rib fractures (P = 0.04, odds ratio = 2.8, 95%CI: 1.4–5.6). This finding is clinically important as thoracic injuries were the second most frequent co-injuries in our study population and potentially contributed to the respiratory complications in these patients. Among patients with unplanned ICU admissions for respiratory complications, 13.8% had respiratory comorbidities. Patients with unplanned ICU admissions for respiratory complications had more than twice the mortality of the general trauma ICU population.

Table 5.

Characteristics of patients with unplanned intensive care unit admissions due to respiratory complications, n (%)

Variable	Respiratory complications (n = 80)
Age (yaers) (mean)	69.0
Geriatric	52 (65.0)
Sex (male/female)	53 (66.3)/27 (32.7)
Comorbidities	72 (90.0)
Mechanism of injury	-
Fall	50 (62.5)
Motor vehicle	28 (35.0)
Glasgow Coma Scale (mean)	14.3
ISS (mean)	11.9
ISS ≥ 16	22 (27.5)
Upgrade/bounce back	30 (37.5)/50 (62.5)
Main injury	-
Head-traumatic brain injury	16 (20.0)
Thorax	26 (32.5)
Spine	14 (17.5)
Hip/pelvis	9 (11.3)
Abdominal	5 (6.3)
Extremities	3 (3.8)
Facial	5 (6.3)
Pulmonary contusion	7 (8.8)
Pneumothorax	10 (12.5)
Hemothorax	15 (18.8)
Pneumohemothorax	6 (7.5)
Any blood transfusion	39 (48.8)
Any surgical procedure	43 (53.8)
Number of consultations (mean)	3.9
Mechanical ventilation requirement	54 (67.5)
Endotracheal intubation	53 (66.3)
Tracheostomy	13 (16.3)
ICU length of stay (days) (mean)	12.8
Hospital length of stay (days) (mean)	21.1
Mortality	24 (30.0)
Time: Floor-ICU admission (days) (mean)	4.0

ICU: Intensive care unit; ISS: Injury severity score.

Figure 7.

Respiratory causes of unplanned intensive care unit admissions in trauma patients.

DISCUSSION

In our study, unplanned ICU admissions constituted 4.2% of all trauma ICU admissions with a mortality of 25.6%. Rubano et al[5] reported a 3.9% rate of unplanned ICU admissions from all trauma center admissions and a 28.2% rate of unplanned ICU admissions from all trauma ICU admissions, with a mortality of 18.4%.

Within our patients, upgrades constituted 66% and bounce backs 34% of unplanned ICU admissions. On the contrary, Jensen et al[8] reported the opposite numbers for unplanned ICU admissions with 69% being bounce backs and 31% being upgrades.

Bounce backs have been addressed more often in the literature and the rates of bounce backs were reported to be from 3.6% to 5.6% in all adult trauma admissions[6,10,13,20] or from 19.8% to 69% in all unplanned ICU admissions[5,8]. The mortality rates in bounce backs have ranged from 10.8% to 22.3%[6,7,10,12]. In our study, bounce backs accounted for 1.4% of all trauma ICU admissions, or 34% of unplanned ICU admissions with a mortality of 34.8%, which is on the higher end of the reported mortality, which may be due to a higher proportion of geriatric patients.

The rates of upgrades were reported to be around 4.4% in all trauma ICU admissions[4], or from 31% to 80.2 % in unplanned ICU admissions in trauma patients[5,8]. Mortality in upgrades was reported between 5.4% and 20%[4,8]. In our study, the rates were in line with previously reported data, as upgrades accounted for 2.8% of all trauma ICU admissions, or 66% of unplanned ICU admissions with a mortality of 20.9%. In our patients, mortality was statistically significantly higher in bounce backs compared to upgrades. After propensity score matching by ISS, mortality was higher in bounce backs, however, it did not reach the statistical significance.

The frequency of bounce backs can be reduced by recognizing specific risk factors, such as particular comorbidities and/or injuries, in certain categories of patients and by using an aggressive prophylactic treatment to target these risk factors after the patient is transferred to the floor. A reduction in upgrades can be achieved by following best practice guidelines and having institutional algorithms for ICU admission of particular diagnosis-related groups (e.g. direct ICU admission for a geriatric patient with ≥ 3 rib fractures). The comparison of propensity score matched patients revealed that despite comparable injury severity and type of injury, upgrades were elevated from the trauma floor to the ICU earlier than bounce backs, suggesting an initial undertriage and a potentially preventable event.

The wide range of reported numbers of upgrades and bounce backs in different studies can be attributed to different patient mix, variability in the inclusion and exclusion criteria, and to the use of different definitions[1,2]. Some authors limit inclusions to patients admitted to the ICU for 24 hours or more[2,21,22], exclude patients with the initial ICU stay of < 4 hours[23], while others exclude returns within 6 hours[24]. The frequency of unplanned ICU admissions may also be affected by the trauma ICU bed occupancy rates or depend on the demand.

In particular, the timing of the unplanned ICU admissions varies between different studies. It can include the entire time of hospitalization, be limited to just the first 48 hours of floor hospitalization, or include the first 72 hours[1,2,6,13,23]. Currently, there is no standardized, comprehensive, and across-the-board accepted definition of unplanned ICU admissions. It seems logical to include a certain time limit in the definition, as later admissions may be more related to the development of lingering complications than to premature discharge from the ICU or any deficiency in treatment on the floor[25]. Many studies address readmissions within the first 48 hours of initial ICU discharge, as this time frame has stronger relationship with the ICU interventions, such as mechanical ventilation[26,27]. We agree with the opinion of Fakhry et al[13] that since most of the patients (71.6%) are admitted to the ICU within the first 72 hours, this may be an appropriate cut off for trauma patients. In our study, more than 3/4 (78.3%) of patients were admitted to the ICU within the first 72 hours of hospital admission and almost 2/3 within 48 hours. These first few days on the trauma floor are crucial for the prevention of unfavorable developments and should be designated for aggressive preventive treatment.

Geriatric vs non-geriatric comparison

Due to an aging population with a more active lifestyle, geriatric trauma is on the rise and is a subject of renewed interest[28-30]. However, publications regarding unplanned ICU admissions in geriatric trauma patients are scarce[11,31]. In our study of unplanned ICU admissions, geriatric patients had more comorbidities and more falls as MOI than non-geriatric patients, however the ISS was comparable. In both subgroups, upgrades were more common than bounce backs, however upgrades were even more prevalent in geriatric patients compared to non-geriatric patients, suggesting higher initial undertriage in the elderly population. In addition, the time for elevating patients to the ICU was 2 days shorter in geriatric compared to non-geriatric patients. Mortality among our geriatric patients was almost three times higher than in non-geriatric patients and reached 31.9%. In both age groups mortality was higher in bounce backs compared to upgrades and both bounce backs and upgrades mortality was three times higher in geriatric compared to non-geriatric patients. Our data are in agreement with Laytin and Sims[11] who in the analysis of bounce backs also reported a three times higher mortality in geriatric trauma patients compared to adult readmissions. In another analysis of geriatric patients by Mulvey et al[31], bounce backs were twice as common, but bounce backs and upgrades had comparable mortality, around 10%.

Respiratory complications

Several investigators observed a high prevalence of respiratory complications among patients with unplanned ICU admissions[6,10,32]. Respiratory complications were the main cause of unplanned ICU admissions in 40% of our trauma patients. Our results are similar to Yin et al[32] and Jensen et al[8] who reported that in about 40% of patients the primary reason for the return to the ICU within 48 hours or for an unplanned ICU admission was respiratory distress. Furthermore, Ranney et al[4] reported that significant injuries to the thorax and respiratory deterioration were the most common etiologies of trauma ICU upgrades. Multivariable analysis in our study showed that the presence of rib fractures was the only independent predictor for respiratory insufficiency leading to an unplanned ICU admission. With thoracic injuries being the second most frequent co-injuries in our study population, it is of clinical importance to view patients with rib fractures as at risk to develop respiratory complications, which may result in unplanned ICU admissions. The other tested variables, such as chronic obstructive pulmonary disease (COPD), pulmonary contusion and hemo/pneumothorax were not significant predictors. However, in a number of studies, COPD was found to be significantly associated with unplanned trauma ICU readmissions or trauma ICU upgrades[4,6,7].

Respiratory deterioration was the main reason for ICU return, accounting for 60% of upgrades and 62% of bounce backs[4,12]. Other studies also reported high rates of respiratory complications in bounce back patients of 43% and 48.6%[10,13]. Bradburn et al[6] identified unplanned intubation as one of the strongest predictors of ICU bounce backs. Our data is in line, as most of the respiratory complications were in bounce back patients where head and chest injuries were the most common. Other authors also recognized that patients with TBI comprised almost half of the initial readmissions[10]. In our propensity score matched comparison, bounce backs had significantly higher mechanical ventilation requirements, with more endotracheal intubations compared to upgrades. High mortality rates in patients with respiratory complications necessitate proactive search for early signs of respiratory insufficiency.

Among our patients with respiratory complications, the mean time before unplanned ICU admission was 4 days, which indicates that there is available time that should be used for aggressive prophylactic of this complication, such as a mandatory respiratory therapy, early mobilization and dysphagia screening.

Severely injured patients

The ISS of 16 or more is the most commonly used definition of severely injured patients and level 1 and level 2 trauma centers are designated for the treatment of these patients[14,15,33]. Johns[23] found that ISS > 17 was among the risk factors for trauma ICU readmissions. Of all unplanned ICU admissions at our trauma center, patients with ISS ≥ 16 accounted for just above 1/3 and this number was significantly higher among bounce backs compared to upgrades, however there was no statistically significant difference between geriatric and non-geriatric patients. These findings also indicate that the severity of injury per se cannot completely explain all unplanned ICU admissions and that other factors or a combination of factors must be taken into account, such as age, frailty, comorbidities or injury type.

ICU quality of care indicator

Some authors have considered ICU readmission or bounce back rates as a potential indicator of the quality of care for critically ill patients[27,34,35]. In a comparison review Duke et al[35] referred to the suggested < 5% of ICU readmission rates as a recommended benchmark. ICU readmission rate within 48 hours of ICU discharge is a clinical performance measure to gauge ICU safety and the quality of care[36,37]. Al-Jaghbeer et al[38] suggested that ICU readmission rates may not be a good measure of hospital performance, yet may be viewed as “sentinel events” that can be a marker of system-level inefficiencies. Others mentioned that the readmission rate is a crude indicator and is a complementary measure of ICU quality of care, but should only be applied if the patient case-mix is taken into account[39,40].

Discussions between the “quicker and sicker “discharge from the ICU vs the poor quality of treatment received in the ward as the cause of ICU readmission continue[38,41]. It was reported that the premature discharge is likely not the cause of bounce backs and that keeping patients in the ICU longer reduces the occurrence of bounce backs due to more aggressive care, however due to the overall low incidence of bounce backs prolonged ICU stay may be inefficient and cost prohibitive[12]. Delayed ICU discharge of patients with one or more risk variables, or better matching to the receiving unit are also recommended[13]. Van Sluisveld et al[26] did not find an association between the discharge practices and the rates of ICU readmissions. Kramer et al[40] suggested that readmission is more of a proxy for the patient characteristics, particularly the severity of the illness, than a quality measure for ICU. Additionally, the ability of clinicians to predict unplanned readmissions was found to be limited, regardless of the level of experience[3].

Different scores, including the Acute Physiology and Chronic Health Evaluation, the Stability and Workload Index for Transfer, the Sequential Organ Failure Assessment score, the Therapeutic Intervention Scoring System, the Nursing Activity Score and the Clinical Risk of Acute ICU Status during Hospitalization Score have been applied to predict the risk of readmissions, with different rates of accuracy[22,34,42,43].

Practical recommendations

To lessen the amount of unplanned ICU admissions in trauma patients: (1) To reduce upgrades: Improve initial triage, especially among geriatric patients and follow ICU admission guidelines and algorithms; and (2) To reduce bounce backs: After floor admission recognize specific risk factors, focus on the early detection and prophylactic treatment of potential complications.

Patients with TBI or thoracic trauma may require special attention and require adherence to the institutional policies.

Geriatric patients with early onset of respiratory difficulties or those with TBI with notable intracranial bleeding should be considered for a direct admission to the ICU upon hospital arrival.

The first 2-3 days after admission are crucial for the prevention of unplanned ICU admissions and must be dedicated for aggressive targeting of anticipated complications and preventive treatment.

Limitations

The retrospective nature of this study brings up restrictions in prerecorded data and assessments available for extraction from patient’s charts. Although the analysis encompassed data from a considerable amount of time, data from only one level 1 trauma center was included. The participating urban level 1 trauma center is located in a primarily geriatric catchment area.

CONCLUSION

Unplanned ICU admissions constituted 4.2% of all trauma ICU admissions. Although upgrades happened more often, bounce backs required more intensive interventions and prolonged hospital care and were associated with worse outcomes, particularly among geriatric patients. Traumatic brain injuries and thoracic injuries together accounted for more than half of the injuries in patients who required an unplanned ICU admission and this tendency was more pronounced in bounce backs and in geriatric patients. Three quarters of unplanned ICU admissions occurred within the first 72 hours of hospitalization. The main reason for unplanned ICU admissions was respiratory complication. Patients with unplanned ICU admissions had twice the mortality of general trauma ICU patients. The first three days after admission are crucial for the prevention of unplanned ICU admissions and must be dedicated to preventive treatment for any anticipated complications.

Data sharing statement

Deidentified data and study materials are available upon reasonable request from the corresponding author at alexander.fokin@tenethealth.com.