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Prevalence and risk factors associated with delirium at a critical care unit

Abstract

Objective

Identify the prevalence and risk factors associated with delirium in patients in a critical care unit in northeastern Brazil.

Methods

A cross-sectional study that enrolled 316 patients with at least 48h of hospitalization, ≥18 years old, with Richmond Agitation-Sedation Scale ≥ -3, between July 2017 and April 2018. Statistical analysis included univariate and multivariate analysis, we employed a log-binomial model for adjusted prevalence ratios.

Results

Univariate analysis indicated that delirium was prevalent among 45.9%, middle age (49.8 ± 17.4 vs. 44.0 ± 17.6, p=0.003) and neurosurgery (62.5% vs. 26.1%, p<0.001). Physical restraining (81.3% vs. 40.9%, p<0.001), nasoenteral tube feeding (85.9% vs. 57.6%, p<0.001) and mechanical ventilation (50.0% vs. 29.2%, p<0.001) was associated with prevalence of delirium .

Conclusion

Age, physical restraint, tube feeding, and the use of anticonvulsants increase the prevalence of delirium in our sample.

Delirium; Prevalence; Epidemiology; Critical care; Intensive care units; Risk factors

Resumo

Objetivo

Identificar a prevalência e os fatores de risco associados ao delirium em pacientes internados em uma unidade de terapia intensiva no nordeste do Brasil.

Métodos

Estudo transversal realizado entre julho de 2017 e abril de 2018 com 316 pacientes hospitalizados por pelo menos 48h, ≥18 anos, com Richmond Agitation-Sedation Scale ≥ -3. A análise estatística incluiu análise univariada e multivariada; um modelo log-binomial foi utilizado para razões de prevalência ajustadas.

Resultados

A análise univariada indicou uma prevalência de delirium em 45,9%, meia idade (49,8 ± 17,4 vs. 44,0 ± 17,6, p=0,003) e neurocirurgia (62,5% vs. 26,1%, p<0,001). A contenção física (81,3% vs. 40,9%, p<0,001), alimentação por sonda nasoenteral (85,9% vs. 57,6%, p<0,001) e ventilação mecânica (50,0% vs. 29,2%, p<0,001) foram associadas à prevalência de delirium.

Conclusão

Idade, contenção física, alimentação por sonda e uso de anticonvulsivantes aumentaram a prevalência de delirium em nossa amostra.

Delirium; Prevalência; Epidemiologia; Cuidados críticos; Unidades de terapia intensive; Fatores de risco

Resumen

Objetivo

Identificar la prevalencia y los factores de riesgo asociados al delirium en pacientes internados en una unidad de cuidados intensivos en el nordeste de Brasil.

Métodos

Estudio transversal realizado entre julio de 2017 y abril de 2018 con 316 pacientes hospitalizados por al menos 48 horas, ≥18 años, con Richmond Agitation-Sedation Scale ≥ -3. El análisis estadístico incluyó análisis univariado y multivariado. Se utilizó un modelo log-binomial para razones de prevalencia ajustadas.

Resultados

El análisis univariado indicó una prevalencia de delirium en el 45,9 %, mediana edad (49,8 ± 17,4 vs. 44,0 ± 17,6, p=0,003) y neurocirugía (62,5 % vs. 26,1 %, p<0,001). La contención física (81,3 % vs. 40,9 %, p<0,001), alimentación por sonda nasoenteral (85,9 % vs. 57,6 %, p<0,001) y ventilación mecánica (50,0 % vs. 29,2 %, p<0,001) fueron factores asociados a la prevalencia de delirium.

Conclusión

Edad, contención física, alimentación por sonda y uso de anticonvulsivos aumentaron la prevalencia de delirium en nuestra muestra.

Delirium; Prevalencia; Epidemiología; Cuidados criticos; Unidades de cuidados intensivos; Fatores de riesgo

Introduction

Delirium has a quick onset in the intensive care unit (ICU). ( 11. Ely EW , Margolin R , Francis J , May L , Truman B , Dittus R , et al . Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) . Crit Care Med . 2001 ; 29 ( 7 ): 1370 - 9 . ) It may affect older and frail patients with functional disability and dementia. ( 22. Adamis D , Treloar A , Martin FC , Gregson N , Hamilton G , Macdonald AJ . APOE and cytokines as biological markers for recovery of prevalent delirium in elderly medical inpatients . Int J Geriatr Psychiatry . 2007 ; 22 ( 7 ): 688 - 94 . ) Patients with delirium receive more sedation and higher doses of drugs such as midazolam and fentanyl, as well as continuous infusions of dexmedetomidine, propofol, and fentanyl. ( 33. Yamamoto T , Mizobata Y , Kawazoe Y , Miyamoto K , Ohta Y , Morimoto T , et al . Incidence, risk factors, and outcomes for sepsis-associated delirium in patients with mechanical ventilation: a sub-analysis of a multicenter randomized controlled trial . J Crit Care . 2020 ; 56 : 140 - 4 . )

As a consequence, delirium worsens clinical conditions, increases the need for care, prolongs hospitalization, and increases mortality risk. ( 44. Pan Y , Jiang Z , Yuan C , Wang L , Zhang J , Zhou J , et al . Influence of physical restraint on delirium of adult patients in ICU: a nested case-control study . J Clin Nurs . 2018 ; 27 ( 9-10 ): 1950 - 7 . ) Furthermore, delirium is associated with age and gender-specific frailty, medical condition, and dementia. ( 55. Geriatric Medicine Research Collaborative . Delirium is prevalent in older hospital inpatients and associated with adverse outcomes: results of a prospective multi-centre study on World Delirium Awareness Day . BMC Med . 2019 ; 17 ( 1 ): 229 . ) A cohort study estimated that cumulative costs for delirium treatment over 30 days ranged from $11,132 to $23,497 ( 66. Vasilevskis EE , Chandrasekhar R , Holtze CH , Graves J , Speroff T , Girard TD , et al . The Cost of ICU Delirium and Coma in the Intensive Care Unit Patient . Med Care . 2018 ; 56 ( 10 ): 890 - 7 . ) dollars. A meta-analysis ( 77. Krewulak KD , Stelfox HT , Leigh JP , Ely EW , Fiest KM . Incidence and Prevalence of Delirium Subtypes in an Adult ICU: a systematic review and meta-analysis . Crit Care Med . 2018 ; 46 ( 12 ): 2029 - 35 . ) identified that prevalence of delirium associates with worse clinical outcomes and occurrence of adverse events. ( 88. Salluh JI , Soares M , Teles JM , Ceraso D , Raimondi N , Nava VS , Blasquez P , Ugarte S , Ibanez-Guzman C , Centeno JV , Laca M , Grecco G , Jimenez E , Árias-Rivera S , Duenas C , Rocha MG ; Delirium Epidemiology in Critical Care Study Group . Delirium epidemiology in critical care (DECCA): an international study . Crit Care . 2010 ; 14 ( 6 ): R210 . )

Delirium in ICU can be considered a critical problem based on its prevalence, cost, and negative impacts on patients’ quality of life, calling for interventions for treatment and prevention based on its risk factors. Among risk factors, the non-modifiable risk factors associated with delirium in the ICU include age, dementia, and stroke. Potentially modifiable factors involve pharmacological treatment with benzodiazepine, opioids, sedatives, analgesic, hypoxemia, metabolic disorders, and severity of illness. ( 99. Smith M , Meyfroidt G . Critical illness: the brain is always in the line of fire [ editorial ]. Intensive Care Med . 2017 ; 43 ( 6 ): 870 - 3 . , 1010. Faria RS , Moreno RP . Delirium in intensive care: an under-diagnosed reality . Rev Bras Ter Intensiva . 2013 ; 25 ( 2 ): 137 - 47 . Review . ) Finally, modifiable factors include isolation, excessive use of technology, equipment, changes in sleep and wakefulness, ( 99. Smith M , Meyfroidt G . Critical illness: the brain is always in the line of fire [ editorial ]. Intensive Care Med . 2017 ; 43 ( 6 ): 870 - 3 . ) physical restraint, and the use of enteral nutrition, urinary catheters, and central venous catheters. ( 1010. Faria RS , Moreno RP . Delirium in intensive care: an under-diagnosed reality . Rev Bras Ter Intensiva . 2013 ; 25 ( 2 ): 137 - 47 . Review . )

Interventions focused on modifiable risk factors may ensure patients’ health outcomes in clinical practice. However, existing guidelines for prevention and treatment of delirium are non-specific, providing limited guidance for pain, agitation, sedation, immobility, and disturbed sleep in ICU patients. Furhermore, there is a gap in the evidence between theoretical guidance and clinical practice; thus, the absence of specific guidelines along with a wide variety of therapeutic arsenal lead to a lack of consensus in treatment. ( 1111. Cascella M , Fiore M , Leone S , Carbone D , Di Napoli R . Current controversies and future perspectives on treatment of intensive care unit delirium in adults . World J Crit Care Med . 2019 ; 8 ( 3 ): 18 - 27 . Review . )

This study aims to identify the prevalence and risk factors associated with delirium among patients in a critical care unit in northeastern Brazil.

Methods

Population and sample characterization

Hospitalized patients aged 18 years or older, admited for at least 48h at medical and surgical intensive care units (ICU) at the Sergipe Emergency Hospital (HUSE) in the state of Sergipe, northeastern Brazil, were enrolled in an observational cross-sectional study between August 2017 and October 2018. The ICU has a functional capacity of fifty-four beds.

The sample size was calculated considering the delirium outcome based on the multicenter study by Salluh et al. (2010) ( 88. Salluh JI , Soares M , Teles JM , Ceraso D , Raimondi N , Nava VS , Blasquez P , Ugarte S , Ibanez-Guzman C , Centeno JV , Laca M , Grecco G , Jimenez E , Árias-Rivera S , Duenas C , Rocha MG ; Delirium Epidemiology in Critical Care Study Group . Delirium epidemiology in critical care (DECCA): an international study . Crit Care . 2010 ; 14 ( 6 ): R210 . ) developed in intensive care units in South America (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, and Uruguay); North America (Mexico and the United States) and Europe (Spain), in which the prevalence of delirium was 32.3%. A prevalence of at least 28% was assumed. Pocock’s ( 1212. Pocock SJ . Clinical Trials: a Practical Approach . Chichester : John Wiley & Sons, Inc ; 1983 . p. 123 - 41 . ) calculation was used, and an expected error of 5% was assumed. The calculation yield a sample size of 310 patients.

Patients with at least 48h of hospitalization, at 18 years old or older, sedated or weaned, with Richmond Agitation-Sedation Scale (RASS) ≥ -3 (moderate sedation with eye movement or opening of the eyes) were included. Critically ill patients with a Glasgow score ≤8, aphasia, brain death, or who were in custody were excluded. This study was approved by the Ethics Committee of the Federal University of Sergipe on May 8th, 2017, under opinion number 2.051.128.

Variables and Data collection

Predisposing and precipitating risk factors for delirium included sociodemographic data, gender, age, medical diagnosis according to ICU admission, cause of hospitalization, medical history, smoking, alcohol consumption, visual impairment, history of depression, dementia, heart failure, stroke, epilepsy, kidney disease, liver disease, HIV infection, the use of psychotropic drugs, malnutrition, and hypertension. Data collection of precipitants factors related to current hospitalization included RASS Scale Score, ( 1313. Nassar AP , Pires-Neto RC , Figueiredo WB , Park M . Validity, reliability and applicability of Portuguese versions of sedation-agitation scales among critically ill patients . Sao Paulo Med J . 2008 ; 126 ( 4 ): 215 – 9 . ) dehydration, hydro electrolytic disorder, glycemic alteration, high blood pressure, hypothermia, fever, hypoxemia, immobility, physical restraint, tube feeding, mechanical ventilation, central venous catheter, and urinary catheter, and the Prognostic Comorbidity Index of Charlson. ( 1414. Charlson ME , Pompei P , Ales KL , MacKenzie CR . A new method of classifying prognostic comorbidity in longitudinal studies: development and validation . J Chronic Dis . 1987 ; 40 ( 5 ): 373 - 83 . ) The Glasgow Coma Scale (GCS) was used to evaluate consciousness in comatose patients with traumatic brain injury (TBI) and classified in mild (GCS 13 to 15), moderate (GCS 9 to 12), or severe GCS ≤ 8. ( 1515. Teasdale G , Jennett B . Assessment of coma and impaired consciousness. A practical scale . Lancet . 1974 ; 2 ( 7872 ): 81 - 4 . )

Delirium assessment

The Confusion Assessment Method in an Intensive Care Unit (CAM-ICU) ( 11. Ely EW , Margolin R , Francis J , May L , Truman B , Dittus R , et al . Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) . Crit Care Med . 2001 ; 29 ( 7 ): 1370 - 9 . , 1616. Gusmao-Flores D , Salluh JI , Dal-Pizzol F , Ritter C , Tomasi CD , Lima MA , et al . The validity and reliability of the Portuguese versions of three tools used to diagnose delirium in critically ill patients . Clinics . 2011 ; 66 ( 11 ): 1917 - 22 . ) was used to assess delirium . All assessments were performed by a team of volunteer nurses and undergraduate nursing and medical students previously trained in the RASS, GCS, CAM-ICU evaluation, and secondary data handling. Data were collected in two stages. First, we evaluated patients sedated or awake with the RASS scale and comatose patients with the CGS scale. In the second stage, CAM-ICU was implemented. All data were retrieved from the medical records at the time of enrollment in the study, and all scales results were included in medical records.

Data analysis

We described categorical variables with absolute frequency and relative percentage and continuous variables with mean and standard deviation. Exact Tests of Fisher, Pearson’s Chi-Square, and Pearson Chi-Square with Monte-Carlo simulations were used for testing associations between categorical variables. The Shapiro-Wilk was used for testing continuous variables adherence to normal distribution. T -test for independent samples or Mann-Whitney tests were used for evaluating differences in continuous variables. Crude prevalence ratios were estimated and adjusted by log-binomial regression and the Backward Selection method for variable selection with an input significance of 10%. In all analyses, only valid observations were considered. We adopted 5% as the significance level and used the R Core Team 2019 software for all the analyses.

Results

Eight hundred and thirty-five patients were screened, and 316 met the inclusion criteria. Delirium was prevalent among 45.9% of subjects. Participants were categorized into two groups according to the presence or absence of delirium . Association between delirium , medical, and demographic variables is described in table 1 . The prevalence of middle age (49.8 ± 17.4 vs . 44.0 ± 17.6, p =0.003) and neurosurgery (62.5% vs 26.1%, p<0.001) was significantly higher in the delirium group.

Table 1
Clinical and demographic characterization according to the occurrence of delirium

Among factors associated with delirium, a univariate analysis yield higher frequency of patients in physical restraint (81.3% vs. 40.9%, p<0.001), nasoenteral tube feeding (85.9% vs. 57.6%, p<0.001), and in use of mechanical ventilation (50.0% vs. 29.2%, p<0.001) in the group with delirium when compared to those in the group without it. In addition, patients with delirium had a higher incidence of pressure ulcer (33.3% vs. 189%, p=0.004), received more fentanyl as sedative (24.8% vs. 8.2%, p<0.001), more muscle relaxants, (4.8% vs 0.6%, p=0.027) and required more vasopressor (9.0% vs. 2.9%, p=0.021) and anticonvulsants (35.2% vs. 19.9%, p=0.002) medications when compared to those without delirium ( Table 2 ).

Table 2
Clinical and hospitalization characterization according to the occurrence of delirium

We estimated crude prevalence ratios from 10% significant variables in univariate analysis, attempting to create multiple models for delirium . We observed that higher crude prevalence ratios in delirium were linked to age, surgical approach by neurosurgery, physical restrainment, enteral tube feeding, use of mechanical ventilation, presence of pressure ulcer, use of fentanyl, anticonvulsant, and muscle relaxants. In multiple models, we observed higher prevalence ratios for delirium by age, physical restrainment, enteral tube feeding, anticonvulsant, and muscle relaxants ( Table 3 ).

Table 3
Log-binomial regression analysis of variables associated with delirium

Discussion

In our study, the mean age for delirium was 49.8 years, compared to 44 years for those without delirium . Age is a critical risk factor for delirium . One study indicated that surgical or critical patients aged 72 to 86 years of age develop delirium during hospitalization. ( 1717. Zrour C , Haddad R , Zoghbi M , Kharsa Z , Hijazi M , Naja W . Prospective, multi-centric benchmark study assessing delirium: prevalence, incidence and its correlates in hospitalized elderly Lebanese patients . Aging Clin Exp Res . 2020 ; 32 ( 4 ): 689 - 97 . ) Predisposition to delirium seems to increase with aging, as hospitalized older adults are more likely to develop confusional mental states. ( 1818. Marcantonio ER . Delirium in Hospitalized Older Adults . N Engl J Med . 2017 ; 377 ( 15 ): 1456 - 66 . Review . ) However, both age groups in our sample were characterized by middle-aged individuals. This can be explained by the cause of hospitalization, mostly associated to trauma and neurovascular injuries.

Surgical patients were more likely to develop delirium in our sample; however, both surgical and clinical neurological patients were significantly at risk, particularly those with strokes and traumatic brain injury. Other studies investigated the relationship between cause of hospitalization and delirium . Mesa et al. ( 1919. Mesa P , Previgliano IJ , Altez S , Favretto S , Orellano M , Lecor C , et al . Delirium in a Latin American intensive care unit. A prospective cohort study of mechanically ventilated patients . Rev Bras Ter Intensiva . 2017 ; 29 ( 3 ): 337 - 45 . ) found a higher prevalence among clinical patients, while Wang et al. ( 2020. Wang J , Ji Y , Wang N , Chen W , Bao Y , Qin Q , et al . Risk factors for the incidence of delirium in cerebrovascular patients in a Neurosurgery Intensive Care Unit: a prospective study . J Clin Nurs . 2018 ; 27 ( 1-2 ): 407 - 15 . ) found that neurosurgical ICU patients had had a higher incidence (42.2%) 4.5 days after admission. Wang also described that patients subjected craniotomies or other surgeries longer than 3 hours had higher prevalence of delirium. ( 2020. Wang J , Ji Y , Wang N , Chen W , Bao Y , Qin Q , et al . Risk factors for the incidence of delirium in cerebrovascular patients in a Neurosurgery Intensive Care Unit: a prospective study . J Clin Nurs . 2018 ; 27 ( 1-2 ): 407 - 15 . )

Our results reflect the local characteristics of Sergipe ICU were trauma and cerebral injury account for the majority of admissions. Intracranial hematomas (epidural or subdural), traumatic brain injury reduce frontal and temporal brain volume; therefore, mood and behavioral changes are expected among our subjects ( 2121. Jotz GP , Marrone AC , Stefanni MA , Bizzi JW , Aquini MG . Neuroanatomia clínica e funcional . Amsterdã : Elsevier ; 2017 . 352 p. ) and may explain the higher prevalence of delirium in our sample.

Additionaly, mechanic restraint, enteral nutrition, and mechanic ventilation were associated ( p<0.001) with delirium in our study along with pressure ulcer ( p =0.004), GCS̸ TBI ( p =0.041), fentanyl ( p <0.001), noradreline (p =0.021), anticonvulsants ( p =0.002) and muscle relaxant ( p =0.027).

We found a significant correlation [RP 3,00 (2,08-4,22); p<0,001] between delirium and physical restraint, that is, when a patient is physically restrained to its hospital bed. Other studies corroborate to this evidence. Kwizera et al. ( 2222. Kwizera A , Nakibuuka J , Ssemogerere L , Sendikadiwa C , Obua D , Kizito S , et al . Incidence and Risk Factors for Delirium among Mechanically Ventilated Patients in an African Intensive Care Setting: an observational multicenter study . Crit Care Res Pract . 2015 ; 2015 : 491780 . ) found that about 80% of physically restrained patients exhibit delirium . A lower delirium prevalence (39%) was observed in a case-control study with physically restraining Chinese ICU patients conducted by Pan et al. ( 44. Pan Y , Jiang Z , Yuan C , Wang L , Zhang J , Zhou J , et al . Influence of physical restraint on delirium of adult patients in ICU: a nested case-control study . J Clin Nurs . 2018 ; 27 ( 9-10 ): 1950 - 7 . ) A Swiss multicenter ICU study investigated the pros and cons of mechanic restrain exploring the controversial aspects and adverse events associated with this intervention. The authors evaluated the decision of its implementation in healthcare practice and found that physical restrain is effective in preventing adverse events. ( 2323. Perren A , Corbella D , Iapichino E , Di Bernardo V , Leonardi A , Di Nicolantonio R , et al . Physical restraint in the ICU: does it prevent device removal? Minerva Anestesiol . 2015 ; 81 ( 10 ): 1086 - 95 . )

Conversely, Palacios-Ceña investigated physical restraint in Spanish ICUs with a focus group of physicians and nurses reporting indiscriminate use of restrictions. ( 2424. Palacios-Ceña D , Cachón-Pérez JM , Martínez-Piedrola R , Gueita-Rodriguez J , Perez-de-Heredia M , Fernández-de-las-Peñas C . How do doctors and nurses manage delirium in intensive care units? A qualitative study using focus groups . BMJ Open . 2016 ; 6 ( 1 ): e009678 . ) Furthermore, delirium was underdiagnosed, undertreated, and confounded with other mental confusion pathologies. In the same study, physicians were not prompt to diagnose delirium and prescribed drug pharmacodynamics and pharmacokinetics uncarefully. This fact worsened during night shifts, and the choice of medication was determined without a clearly defined protocol.

Delirium was associated with enteral tube feeding in previous studies. ( 2525. Crenitte MR , Avelino-Silva TJ , Apolinario D , Curiati JA , Campora F , Jacob-Filho W . Predictors of Enteral Tube Feeding in Hospitalized Older Adults . JPEN J Parenter Enteral Nutr . 2017 ; 41 ( 8 ): 1423 - 5 .

26. Pereira SR , Coelho MJ , Mesquita AM , Teixeira AO , Graciano SA . Causes for the unplanned removal of the feeding tube in intensive care . Acta Paul Enferm . 2013 ; 26 ( 4 ): 338 - 44 .
- 2727. Xing J , Yuan Z , Jie Y , Liu Y , Wang M , Sun Y . Risk factors for delirium: are therapeutic interventions part of it? Neuropsychiatr Dis Treat . 2019 ; 15 : 1321 - 27 . ) A study conducted at a university hospital in São Paulo, Brazil, indicated that 36.4% of patients with enteral nutrition had delirium . Conversely, delirium was an independent predictor for 20% tube feeding indications. ( 2525. Crenitte MR , Avelino-Silva TJ , Apolinario D , Curiati JA , Campora F , Jacob-Filho W . Predictors of Enteral Tube Feeding in Hospitalized Older Adults . JPEN J Parenter Enteral Nutr . 2017 ; 41 ( 8 ): 1423 - 5 . ) Individuals experiencing delirium are more likely to remove their enteral tube and suffer adverse events that may prolong their hospitalization and worsen clinical condition. A study conducted in a private ICU in Rio de Janeiro, Brazil, indicated that 50% of patients removed their tube feeding and this adverse event was associated with cognitive impairment, confusion, and delirium. ( 2626. Pereira SR , Coelho MJ , Mesquita AM , Teixeira AO , Graciano SA . Causes for the unplanned removal of the feeding tube in intensive care . Acta Paul Enferm . 2013 ; 26 ( 4 ): 338 - 44 . ) Association between patients removal of tube feeding and cognitive impairment is well-documented in the international literature, mainly observed in 79.3% of patients in a Chinese study. ( 2727. Xing J , Yuan Z , Jie Y , Liu Y , Wang M , Sun Y . Risk factors for delirium: are therapeutic interventions part of it? Neuropsychiatr Dis Treat . 2019 ; 15 : 1321 - 27 . )

Mechanical ventilation was associated with delirium ( 2727. Xing J , Yuan Z , Jie Y , Liu Y , Wang M , Sun Y . Risk factors for delirium: are therapeutic interventions part of it? Neuropsychiatr Dis Treat . 2019 ; 15 : 1321 - 27 . , 2828. Mehta S , Cook D , Devlin JW , Skrobik Y , Meade M , Fergusson D , Herridge M , Steinberg M , Granton J , Ferguson N , Tanios M , Dodek P , Fowler R , Burns K , Jacka M , Olafson K , Mallick R , Reynolds S , Keenan S , Burry L ; SLEAP Investigators ; Canadian Critical Care Trials Group . Prevalence, risk factors, and outcomes of delirium in mechanically ventilated adults . Crit Care Med . 2015 ; 43 ( 3 ): 557 - 66 . ) and increased the duration of mechanical ventilation by 1.85 times. ( 2828. Mehta S , Cook D , Devlin JW , Skrobik Y , Meade M , Fergusson D , Herridge M , Steinberg M , Granton J , Ferguson N , Tanios M , Dodek P , Fowler R , Burns K , Jacka M , Olafson K , Mallick R , Reynolds S , Keenan S , Burry L ; SLEAP Investigators ; Canadian Critical Care Trials Group . Prevalence, risk factors, and outcomes of delirium in mechanically ventilated adults . Crit Care Med . 2015 ; 43 ( 3 ): 557 - 66 . ) A multicenter study between United States and Canada found that delirium patients had twice the duration of mechanical ventilation and hospitalization lengths 1.5 times longer than others without delirium. ( 2828. Mehta S , Cook D , Devlin JW , Skrobik Y , Meade M , Fergusson D , Herridge M , Steinberg M , Granton J , Ferguson N , Tanios M , Dodek P , Fowler R , Burns K , Jacka M , Olafson K , Mallick R , Reynolds S , Keenan S , Burry L ; SLEAP Investigators ; Canadian Critical Care Trials Group . Prevalence, risk factors, and outcomes of delirium in mechanically ventilated adults . Crit Care Med . 2015 ; 43 ( 3 ): 557 - 66 . )

Jeon et al. ( 2929. Jeon K , Jeong BH , Ko MG , Nam J , Yoo H , Chung CR , et al . Impact of delirium on weaning from mechanical ventilation in medical patients . Respirology . 2016 ; 21 ( 2 ): 313 - 20 . ) investigated the association between delirium and wean off from a mechanical ventilation. Results indicated that non- delirium patients were easily weaned out of mechanical ventilation, had fewer adverse events, and lower need for respiratory support.

Data summarized here may reflect the increased incidence delirium among mehanically ventilated patients. Consequently, when weaning off mechanical ventilation and removal of the endotracheal tube are successful, verbal communication can be restored, potentially promoting physical comfortable, and reducing pain. Besides, it can also reduce anxiety, agitation and impaired communication caused by the endotracheal tube. Thus, the incidence of delirium on mechanically ventilated patients should be investigated, aiming to guide the healthcare team decision-making based on the patient’s clinical conditions, pain-management, and communication in ICU.

Sedation was another risk factor for delirium in our study. Hsieh and colleagues measured the impact of implementating of bundle protocol to awaken sedation, monitoring, and management of delirium. ( 3030. Hsieh SJ , Otusanya O , Gershengorn HB , Hope AA , Dayton C , Levi D , et al . Staged Implementation of Awakening and Breathing, Coordination, Delirium Monitoring and Management, and Early Mobilization Bundle Improves Patient Outcomes and Reduces Hospital Costs . Crit Care Med . 2019 ; 47 ( 7 ): 885 - 93 . ) This package decreased the days of restraint (30% to 26%; <0.001) and led to significant reductions in the length of mechanical ventilation and hospitalization, and reduced hospital costs. The authors also proposed a combination of reduction on daily sedation and passive movement, reducing the risk of pressure ulcers. The findings corroborate that early mobility, regardless of the use of mechanical ventilation, should be adopted whenever it is possible.

Thus, the vulnerability of patients on mechanical ventilation to delirium should be investigated. The non-use of artificial ventilation, when appropriate based on the patient’s clinical conditions, favors communication and minimizes episodes of painful and unpleasant sensations that one may experience in ICU.

In this paper the delirium group, approximately 24.8% of the individuals were sedated with fentanyl. This finding is related to an increase s associated with an increase in the prevalence of delirium more than three times, while the use of anticonvulsants was almost twice as high.

Sedation is commonly used to support medical treatment of critically ill patients in the ICU. In this study, fentanyl, anticonvulsants, and norepinephrine were significantly associated with delirium . Fentanyl is a well-established sedative, used to reduce anxiety and stress ( 3131. Devlin JW , Skrobik Y , Gélinas C , Needham DM , Slooter AJ , Pandharipande PP , et al . Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU . Crit Care Med . 2018 ; 46 ( 9 ): e825-73 . ) while phenytoin, is an anticonvulsant commonly linked to delirium. ( 3232. Lôbo RR , Silva Filho SR , Lima NK , Ferriolli E , Moriguti JC . Delirium . Medicina (Ribeirão Preto) . 2010 ; 43 ( 3 ): 249 - 57 . )

Aside from medication, our study found that pressure ulcers were prevalent, although not statistically significant [RP 1.45 (1.15-1.84)] among participants experiencing delirium . A Brazilian study ( 3333. Barbosa TP , Beccaria LM , Silva DC , Bastos AS . Association between sedation and adverse events in intensive care patients . Acta Paul Enferm . 2018 ; 31 ( 2 ): 194 - 200 . ) identified that over 80% of sedated patients experienced 28 adverse events, and pressure ulcer was the most prevalent of them. Taken together, the factors described above, including sedation, physical immobility, and restriction to a hospital bed can lead to diminished tissue oxygenation and increased the risk for pressure ulcers in patients with delirium .

Interestingly, we also observed that the use of muscle relaxants and anticonvulsants increased the prevalence of delirium . In our study, 37.9% of patients were diagnosed with severe or moderate Traumatic Brain Injury (TBI), which may increase upsurge convulsant episodes. Previous studies found that severe and moderate TBI elevate the incidence of convulsive episodes, particularly those patients with intraparenchymal hemorrhage. ( 3434. Ferraz VR , Panagopoulos AT , Veiga JC , Aguiar GB . Uso de anticonvulsivantes no traumatismo cranioencefálico . J Bras Neurocirur . 2015 ; 23 ( 1 ): 150 - 3 . ) Phenytoin was the drug of choice for anticonvulsant treatment and positively associated with delirium prevention. Another study highlighted the relationship between phenytoin and delirium suggesting an impact on the central nervous system causing nystagmus, ataxia, reduction in coordination and mental confusion, dyskinesia, dystonia, tremor, and others. ( 3535. Ferner RE . Adverse effects of phenytoin and fosphenytoin . Adv Drug Reaction Bulletin . 2017 ; 306 ( 1 ): 1183 – 6 . )

Our study highlights the need for improvement through scientific evidence on the identification of delirium and its risk factors. Further studies are warranted to ascertain benefits, applicability, effectiveness, and costs in monitoring and treatment of delirium . Our study has limitations. It is an observational study and does not identify the source or causation for factors here associated with delirium . Second, subjects enrolled in this study were evaluated by multiple investigators due to the hospital characteristics, and schedule, which may imply bias or errors at assessment. Lastly, despite the large sample size, we collected data at one hospital only, which may limit the generalization of our data.

Conclusion

Our study indicated a 45.9% prevalence of delirium in adult participants (mean age 49.8 years old). Key associated factors with delirium include physical restraint, tube feeding for enteral nutrition and mechanical ventilation. Use of anticonvulsants and muscle relaxants were associated with delirium on multivariate analysis. Additionally, delirium patients exhibit more pressure ulcers, received more fentanyl, noradrenaline, and anticonvulsants. We highlight the importance of screening ICU delirium and its risk factors, investigating the many confounders that keep delirium neglected or underreported. The epidemiological description and associated factors identified in our study shed light on delirium occurrence from a regional perspective. Thus, the present study need more research that care planning for best clinical practices for sedation, respiratory e nutritional support, among with other risk factors delirium in intensive care unity.

Acknowledgments

We want to thank the Coordination for the Improvement of Higher Education Personnel (CAPES), Department of Nursing (DENL), the Graduate Program in Health Sciences (PPGCS), professionals of the collection institutions, and all the researchers participating in the Study Group for supporting this study. The present results were used by first author Fernanda Gomes de Magalhães Soares Pinheiro for her Ph.D. thesis at the Federal University of Sergipe as a requirement of the Doctorate Program in Health Sciences.

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Edited by

Associate Editor (Peer review process): Edvane Birelo Lopes De Domenico (https://orcid.org/0000-0001-7455-1727) Escola Paulista de Enfermagem, Universidade Federal de São Paulo, SP, Brazil

Publication Dates

  • Publication in this collection
    29 Aug 2022
  • Date of issue
    2022

History

  • Received
    16 Mar 2021
  • Accepted
    7 Dec 2021
Escola Paulista de Enfermagem, Universidade Federal de São Paulo R. Napoleão de Barros, 754, 04024-002 São Paulo - SP/Brasil, Tel./Fax: (55 11) 5576 4430 - São Paulo - SP - Brazil
E-mail: actapaulista@unifesp.br