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Journal of PeriAnesthesia Nursing 35 (2020) 478e483

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Journal of PeriAnesthesia Nursing

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Research

Emergence Delirium in Elderly Patients as a Potential Predictor of Subsequent Postoperative Delirium: A Descriptive Correlational Study

Jingying Huang, MD a, Haiou Qi, MD b, *, Kai Lv, MD a, Xiangping Chen, MD c, Yiyu Zhuang, MD b, Lili Yang, PhD d

a Postanesthesia Care Unit, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, PR China b Nursing Department, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, PR China c Intensive Care Unit, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, PR China d Nursing Education Department, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, PR China

Keywords: elderly patients emergence delirium postoperative delirium correlation

Conflict of interest: None to report. Funding: This work was supported by the nursing r

Shaw Hospital (no. 201704HL). The funding source w the research process. * Address correspondence to Haiou Qi, Nursing De

Hospital, Zhejiang University School of Medicine, Han E-mail address: [email protected] (H. Qi).

https://doi.org/10.1016/j.jopan.2019.11.009 1089-9472/© 2020 Published by Elsevier, Inc. on beh

a b s t r a c t

Purpose: This study aimed to investigate the incidence of emergence delirium (ED) in elderly patients under general anesthesia and to determine the correlation between ED and delirium at five subsequent postoperative days. Design: This research is a descriptive correlational study. Methods: A total of 168 aged patients undergoing elective general anesthesia were recruited from a comprehensive tertiary teaching hospital with 2,400 beds in Southern China from April 2018 to September 2018. The Nursing Delirium Screening Scale was used to assess delirium at 30 and 60 minutes after extubation or on discharge from the postanesthesia care unit. Patients were assessed for delirium at postoperative days one through five using the same method. Patients' demographic information, including cognitive function, were collected. Findings: Among the 168 aged patients, 58 suffered from ED (34.5%), including the 79.3% for the 46 patients who experienced postoperative delirium (POD). A positive correlation existed between ED and POD (c2 ¼ 111.744; P < .01). Logistic regression analysis included seven variables: age, preoperative Mini- Mental State Examination score, underlying diseases, American Society of Anesthesiologists grade, sur- gery duration, postoperative complications, and the presence of ED. Age and ED were concluded to be independent predictive factors of POD. Conclusions: ED in the first hour after tracheal tube removal is a predictor of delirium at five subsequent postoperative days. Accurate and timely assessment of recovery period can effectively guide the treat- ment and rehabilitation of POD and maximize prevention of adverse consequences.

© 2020 Published by Elsevier, Inc. on behalf of American Society of PeriAnesthesia Nurses. All rights reserved.

Delirium refers to an acute disturbance of consciousness and changes in cognitive functions manifested by declining memory, attention deficit, and reduced level of consciousness.1 Postoperative delirium (POD) refers to delirium of patients after a surgical oper- ation. As a common operative complication, POD can affect patients

esearch funds for Sir Run Run as not involved in any part of

partment, Sir Run Run Shaw gzhou 310020, PR China.

alf of American Society of PeriAnes

of all ages, especially aged patients (65 years and older). The inci- dence of POD in elderly patients ranges between 5% and 50%2 and depends on the type of operation and different sample population groups. The incidence of POD is approximately 4.4% after cataract surgery, 12% after ear, nose, and throat operations, 13% after general surgery, 21.4% after neurosurgery, and more than 50% after abdomen and heart operations.3-6 Emergence delirium (ED) immediately occurs after anesthesia administration (before pro- ceeding to or while in postanesthesia care unit [PACU]). In previous guidelines, the onset time of ED is 1 to 3 days after operation.7,8 The Guideline for Postoperative Delirium based on Evidences and Expert Consensus,9 which was issued by the European Society of Anaes- thesiology (ESA) (2017 version), indicates that the onset of POD

thesia Nurses. All rights reserved.

Huang et al. / Journal of PeriAnesthesia Nursing 35 (2020) 478e483 479

starts from PACU to the fifth day after operation. For the first time, the ESA guideline extended the onset time of POD, thus reducing misdiagnosis of POD and highlighting the importance of ED assessment. Because of different target populations, different screening methods, and differences in treatment and care, the incidence of ED varies from 3.7% to 20% in different studies.10-12

The occurrence of POD in older adult is frequently caused by multiple factors depending on the interaction between the patient internal factors and external contributing factors. Evidence from a systematic review suggests that risk factors for noncardiac surgery include age, dementia or cognitive impairment, hearing or visual impairment, alcoholism, and multiple physical disorders.13 Lin and Wang14 systematically evaluated the risk factors of cardiac surgery and observed that age, cognitive impairment, and medical diseases (such as stroke, diabetes, and atrial fibrillation) are risk factors for POD. Poor postoperative analgesia, infection, limited activity, hyp- oxemia, sleep deprivation, and inappropriate use of drugs are common inducing factors of POD. Hyperactive delirium is commonly observed in clinics. Hypoactive delirium, which is characterized by lethargy, indifferent expression, delayed awak- ening of anesthesia, slow speech, and abnormal movement, is difficult to detect and frequently misdiagnosed. These types of delirium alternately appear as mixed types. The neuropathologic and physiological mechanisms of delirium are still in their infancy. The results suggest that the interaction of various biological factors and activation of multiple pathways lead to large-scale destruction of brain neural networks, resulting in delirium.15 An effective method should be developed to appropriately detect and correct the onset period of POD and to provide individualized multidisci- plinary team intervention for the risk factors of POD.

Background

Aging provides opportunities and challenges worldwide. With the improvement of medical equipment and technology, surgical indications have gradually expanded, whereas postoperative complications have declined, and population of aged patients un- dergoing operations is increasing rapidly. The morbidity of post- operative complications in the aged population is considerably higher compared with other population groups, caused by the degeneration of physiological functions and comorbidities among aged patients.16

POD can cause post-traumatic stress disorder, prolong the length of stay in hospitals, and increase spiritual and economic burden on patients and their families. POD is positively correlated with short-term and long-term mortality after operation.17-19 The occurrence rate of cognitive impairment increases with prolonged duration of delirium and delayed treatment.20,21 Risk factors for delirium include preoperative complications, perioperative fasting and water deprivation, water and electrolyte disorders, use of anticholinergic drugs, surgery duration, and intraoperative bleeding. For elderly patients, the ESA guidelines indicate four strong risk factors, namely, cognitive impairment, impaired system function, malnutrition, and sensory impairment.9 Although numerous factors can influence POD, most of them are inferred theoretically or lack supporting empirical evidence.

To date, ED poses a minor concern and is rarely reported in China. Delirium in PACUmay be attributed to the residual effects of general anesthesia. Theoretically, metabolism of anesthesia can be completed in several minutes to hours. Anesthetic medication might feature different pathogeneses with POD. However, whether correlation exists between anesthesia and POD remains unclear.22

Several scholars have suggested that ED can independently pre- dict POD in 1 to 5 days.23 However, no systematic evaluations have been reported, and a limited number of studies have been

conducted. Aged patients constitute the high-risk groups of POD. Existing treatments for delirium are not completely effective,24,25

and no drug can considerably improve patient outcomes.8 Thus, prevention of delirium is critical. In this study, we aimed to investigate the incidence of ED in elderly patients under general anesthesia and to determine the correlation between ED and delirium at postoperative day 5. Other risk factors were evaluated to provide guidance for medical staff in conducting individualized interventionmeasures and rehabilitation decisions tominimize the occurrence of adverse consequences.

Materials and Methods

Purpose and Hypotheses

This study aimed to investigate the incidence of ED in older adults undergoing a surgical procedure with the use of general anesthesia, and to determine whether ED in PACU is associated with the development of POD during postoperative days 1 to 5. We hypothesized that the development of ED in the first hour after endotracheal extubation is an independent predictor of the occur- rence of delirium during postoperative days 1 to 5.

Participants

We recruited elderly patients from a comprehensive tertiary teaching hospital with 2,400 beds in Southern China from April 2018 to September 2018. The inclusion criteria for patients included the following: age 65 years and older; undergoing elective surgery; and intravenous inhalation combined with anesthesia. Exclusion criteria comprise the following: cardiac surgery; diagnosis of mental disorders or organic encephalopathy; hearing and other sensory impairments and inability to communicate normally; diagnosis of hypoxemia in perioperative course (pulse oxygen saturation <90%); preoperative course with a Mini-Mental State Examination (MMSE) score of less than 10; transfer to intensive care unit after returning to the ward; and missing data.

Sample Size and Sampling

This study was an analytical quantitative research. Crude odds ratio approximated 3.96 in a prior study.26 The sample size was based on a desired significance level of .05, power of 0.80, and an effect size of 0.3, featured two tails, and considered dropout of samples, such as patient withdrawal. We selected 160 patients through convenience sampling.

Instruments

The general information questionnaire was independently designed by researchers and included age, gender, history of dis- eases, American Society of Anesthesiologists (ASA) classification, operation type, surgery duration, blood loss, postoperative pain score, postoperative complications, and hypoproteinemia.

The MMSE scale in China revised by Zhang Mingyuan was used as the cognitive function questionnaire.27 This scale covers 11 items, namely, time orientation, location orientation, immediate memory, attention and calculation power, recall, naming, repeti- tion, three-order command, reading and understanding, writing, and depiction. The total score was 30. Patients were diagnosed based on the following scores: 27 to 30, normal cognitive functions; less than 27, cognitive problems; 21 to 27, mild dementia; and 10 to 20, moderate dementia. The joint inspection credibility of this scale was 0.99, and its test-retest reliability was 0.91, indicating high reliability.

Huang et al. / Journal of PeriAnesthesia Nursing 35 (2020) 478e483480

The original Nursing Delirium Screening Scale in Chinese (NU- DESC) is a fast, convenient, and easy-to-operate delirium screening tool developed by Gaudreau et al28 in 2005. This assessment can be accomplished in 1 to 2 minutes using the information collected by medical staff through simple communication with patients during conventional operations. This method is applicable to a fast-paced and dynamic environment, and it is recommended for delirium screening during the perioperative period. NU-DESC covers five items: orientation disorder, inappropriate behavior, inappropriate communication, illusion/hallucination, and psychomotor retarda- tion. Each item was scored based on the severity of symptoms: 0 ¼ inexistent, 1 ¼ mild, and 2 ¼ moderately severe. The total possible score was 10, and patients with a total score of two and/or greater were diagnosed with delirium. Intergroup correlation co- efficient was 0.91. Compared with the gold standard Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V), the sensitivity, specificity, and criterion validity of NU-DESC were 0.80, 0.92, and 0.66, respectively, when the critical score was set to 3 (P < .01).29

Data Collection

Emergence Delirium NU-DESC was used to evaluate delirium signs during PACU stay

at 30 and 60 minutes after extubation or discharge. Patients with positive result at any of these periods were classified with ED.

Postoperative Delirium Delirium evaluation is performed daily within 5 days after sur-

gery or at any time during conscious fluctuating. Any positive evaluation result is defined as POD. Investigators performed the ED and NU-DESC screens. Pain scores at 1 to 3 days after operation were collected through a visual analog scale.

All patients were given a standardized anesthesia program. Sufentanil citrate, propofol, cis-atracurium, sevoflurane, and remi- fentanil hydrochloride were used for precise anesthesia. During the operation, blood pressure was kept at approximately þ20% of the baseline to prevent postoperative cognitive disorder caused by extreme changes in blood pressure. Standard joint drug analgesia was provided to patients after surgery in accordance with pain scores. Research team members were trained and assessed in MMSE scale and NU-DESC scale in Chinese before the study. All research team members were allowed to collect data after passing the assessment.

Ethical Considerations

Before data collection, ethical approval was sought and obtained from the ethics committee. When collecting data before surgery, the researcher clearly explained the study to the participants, who then signed an informed consent form. Voluntary and anonymous participation was guaranteed.

Data Analysis

A databasewas constructed on EpiData 3.0 (Epidata Association) and used for double input and calibrations. After organization, analysis, and correction, datawere processed and analyzed on SPSS, version 23.0 (IBM, Armonk, NY). Numerical data were described by frequency and percentage. Normal distribution of measurement data was described as mean ± SD, whereas abnormal distribution was described as the distance between median and interquartile range. Single-factor analysis was conducted through independent sample t test, c2 test, nonparametric test, and variance analysis.

Multifactor analysis was performed through logistic regression analysis. P < .05 indicates statistical significance of differences.

Results

In this study, 168 elderly patients (65 to 90 years, 72.43 ± 5.25 years mean) were analyzed and included 89 males (52.98%) and 79 females (47.02%). The average operation durations in the POD and non-POD groups were 174.27 ± 56.32 and 128.34 ± 65.69 minutes, respectively. A total of 48 patients (28.57%) suffered from POD, whereas the remaining 120 patients belonged to the non-POD group (71.43%).

Single-Factor Analysis of POD in Elderly Patients

Single-factor analysis was performed on general information and relative risk factors of the subjects. The results showed that elderly patients with POD were influenced by age, preoperative MMSE score, underlying disease, ASA classification, surgery dura- tion, and postoperative complications (P < .05). Table 1 shows the results. No statistically significant difference was observed between the 75 to 79 and older than 80-year group based on pairwise comparison. Meanwhile, statistically significant differences were observed among other age groups (P < .001). Pairwise comparison of underlying disease revealed that diabetic patients were more vulnerable to POD than others (P < .05). No statistically significant differences were observed in patients with other diseases. The incidence of POD presented statistically significant differences be- tween ASA II and III (P¼ .006) and between ASA II and IV (P¼ .028). By contrast, no statistically significant difference was observed between ASA III and IV. Operation durations of 1 to 2 hours and 2 to 3 hours (P ¼ .041), 1 to 2 hours and more than 3 hours (P < .001) influenced the incidence of POD. The remaining groups showed no statistical significance.

Patients With and Without Delirium in PACU and Postoperatively

Table 2 shows the morbidities of ED and POD. Notably, the morbidity of ED reached 34.5%, whereas that of POD totaled 28.6% (c2¼111.744; P< .01). Sensitivity and specificity amounted to 95.8% and 90.0%, respectively. The average length of stay of the ED group was 7.67 ± 2.42 days, whereas that of the non-ED group was 6.05 ± 1.29 days, indicating a statistically significant difference (t ¼ �4.754; P < .001).

Multifactor Analysis of POD in Elderly Patients

POD among elderly patients was used as a dependent variable (negative ¼ 0; positive ¼ 1), whereas age, preoperative MMSE score, underlying diseases, ASA classification, surgery duration, postoperative complications, and ED were used as independent variables. Regression analysis was conducted using a binary logistic forward-likelihood ratio conditional method. Dummy variables of underlying diseases were analyzed based on logistic requirements of independent variables (Table 3).

The results showed that ED and age were correlated with POD (P < .05). Odds ratio values of ED and age were 391.369 and 4.147, respectively (Table 4).

Discussion

Incidence of POD in Elderly Patients Remains High

In this study, the incidence of POD in elderly patients reached 28.6%. Peking Union Medical College Hospital surveyed aged

Table 1 Single-Factor Analysis of Postoperative Delirium in Elderly Patients (N ¼ 168)

Characteristics POD Group (n ¼ 48), n (%)

No POD Group (n ¼ 120), n (%)

Statistical Value

P

Gender 0.038* .845 Male 26 (54.17) 63 (52.50) Female 22 (45.83) 57 (47.50)

Age (y) 29.363* <.001 65-69 5 (10.42) 53 (44.17) 70-74 16 (33.33) 45 (37.50) 75-79 15 (31.25) 15 (12.50) Older than 80 12 (25.00) 7 (5.83)

Preoperative MMSE score

4.652* .031

Normal (27-30) 20 (41.67) 72 (60.00) Cognitive disorder (<27)

28 (58.33) 48 (40.00)

Underlying diseases 8.483* .037 Diabetes 18 (37.50) 21 (17.50) Hypertension 14 (29.17) 39 (32.50) Cardiovascular disease

10 (20.83) 32 (26.67)

Lung disease and other

6 (12.50) 28 (23.33)

ASA classification 8.418* .015 II 13 (27.08) 62 (51.67) III 26 (54.17) 44 (36.67) IV 9 (18.75) 14 (11.66)

Operation type 7.172* .208 Orthopaedics 16 (33.33) 20 (16.67) Thoracic surgery 6 (12.50) 13 (10.83) General surgery 13 (27.08) 39 (32.50) ENT 2 (4.17) 12 (10.00) Urinary surgery 6 (12.50) 16 (13.33) Oncological surgery 5 (10.42) 20 (16.67)

Surgery duration (h) 13.702* .001 <2 4 (8.33) 38 (31.67) 2-3 14 (29.17) 40 (33.33) >3 30 (62.50) 42 (35.00)

Blood loss (mL, x± s) 105.64 ± 82.37 98.38 ± 121.49 1.342y .877 Postoperative

pain score (point, x± s)

3.846z .052

The first day 4.56 ± 1.23 4.39 ± 1.13 The second day 3.08 ± 0.96 2.97 ± 1.24 The third day 2.1 ± 1.12 1.96 ± 0.88

Postoperative complicationsx

12.432* .001

With 22 (45.83) 23 (19.17) Without 26 (54.17) 97 (80.83)

Postoperative hypoproteinemia¶

0.509* .302

With 12 (25.00) 24 (20.00) Without 36 (75.00) 96 (80.00)

POD, postoperative delirium; MMSE, Mini-Mental State Examination; ASA, Amer- ican Society of Anesthesiologists; ENT, ear, nose, and throat.

* Denotes c2 value. y Denotes t value. z Denotes F value. x Postoperative complications: postoperative bleeding, incision infection, incision

dehiscence, urinary tract infection, pulmonary complications, and so on. ¶ Postoperative hypoproteinemia: serum total protein less than 60 g/L or albumin

less than 35 g/L after surgery.

Table 2 Patients With and Without Delirium in PACU and Postoperatively

POD (n) Non-POD (n) Total (n)

ED 46 12 58 Non-ED 2 108 110 Total 48 120 168

PACU, postanesthesia care unit; POD, postoperative delirium; ED, emergence delirium.

Huang et al. / Journal of PeriAnesthesia Nursing 35 (2020) 478e483 481

patients with noncardiac surgery in 2011 and obtained POD inci- dence of 11.1%.30 This study indicated that the incidence of POD continuously increased, and this trend may be related to the following reasons: (1) regional differences exist at the medical level, and anesthetic drugs lack uniform management; (2) respondent groups vary; preoperative cognitive level, operation type, and operation duration can influence delirium of aged pa- tients to a certain extent; and (3) delirium screening tools vary, and medical professionals have increased their knowledge about

delirium in recent years. Approximately 50% of cases of clinical delirium have not been diagnosed or reported in the past. In particular, hypoactive delirium is frequently overlooked, difficult to observe, or misdiagnosed as dementia.31 With the development of enhanced recovery after surgeryeorientedmanagement projects in the perioperative period, PODmanagement has been implemented through enhanced recovery after surgery and has attracted increasing attention. Prevention (eg, adequate pain assessment and promptly diagnosing POD in PACU) and treatment (using low-dose haloperidol or low-dose atypical neuroleptics to treat) options are available to reduce the incidence and duration of POD after emer- gent delirium. Once it occurs, immediate treatment of both caus- ative factors and symptoms has a major impact in reducing POD duration.20,32

Neufeld et al33 evaluated 91 patients under general anesthesia in the recovery period using DSM-IV. They noted that the incidence of ED reaches 45%. In this research, the incidence of ED totaled 34.5%, which was slightly lower than that observed by Neufeld et al. The difference may be due to the higher sensitivity of DSM-IV to delirium compared with NU-DESC. NU-DESC may cause some nurses to focus only on patients' level of consciousness when assessing delirium, while ignoring attention loss, confusion, and orientation judgment, thereby decreasing the recognition rate of delirium.34

POD is Influenced by Age and ED

Numerous studies have proven that age is an independent predictive factor of POD,9 conforming to the results of this study. According to the data in this research, the incidence of POD in aged patients (65 years and older) increases by 3.147 times when age increases by 5 years. This condition results from the decreased reserve function of the brain, degenerative lesions in brain tissues, extensively degenerated cholinergic nerves in brain, gradual decrease in acetylcholine and presynaptic choline receptors with aging, resulting in cognitive impairment. Meanwhile, brain blood flow in elderly patients decreases, metabolic capability of anes- thetics is weakened, and metabolic disorder of brain cells may occur. Elderly patients face this functional hurdle and develop POD when they are stressed by major physiological functions.

Neufeld et al33 observed that 14 of 19 patients with POD (74%) experienced ED. Based on NU-DESC, Radtke et al18 concluded that in PACU, 11% of the patients were observed with delirium, and the rate is 4.2% on the ward on the first postoperative day. Among the 4.2%, 84.2% of themwere already positive for delirium on discharge from PACU (P < .01). Similar to the research conclusions in this study, delirium, which develops 30 minutes after extubation in PACU, was an independent predictive factor of ED after 1 to 5 days of operation.

Several medical staff attributed ED to insufficient metabolism of anesthetic drugs and short-term dysphoria caused by discomfort from trachea cannula. However, no connection was made between delirium signs after 30 minutes of extubation and subsequent development of POD. Patients may miss early intervention and optimal treatment because of inadequate attention on this

Table 3 Independent Variable Assignment for Logistic Regression Analysis

Independent Variable Assignment Method

Age 65-69 ¼ 1, 70-74 ¼ 2, 75-79 ¼ 3, older than 80 ¼ 4

Preoperative MMSE score Normal ¼ 0, cognitive disorder ¼ 1 Underlying diseases Diabetes (Z1 ¼ 1, Z2 ¼ 0, and Z3 ¼ 0);

hypertension (Z1 ¼ 0, Z2 ¼ 1, and Z3 ¼ 0); cardiovascular disease (Z1 ¼ 0, Z2 ¼ 0, and Z3 ¼ 1); lung disease and other (Z1 ¼ 0, Z2 ¼ 0, and Z3 ¼ 0)

ASA classification II ¼ 1, III ¼ 2, and IV ¼ 3 Surgery duration <2 h ¼ 1, 2-3 h ¼ 2, and >3 h ¼ 3 Postoperative complications Without ¼ 0, without ¼ 1 ED Negative ¼ 0, positive ¼ 1

MMSE, Mini-Mental State Examination; ASA, American Society of Anesthesiologists; ED, emergence delirium.

Huang et al. / Journal of PeriAnesthesia Nursing 35 (2020) 478e483482

problem. Although several cases of delirium are reversible, insuf- ficient attention on delirium will prolong the recovery period and increase medical costs, workload of medical staff, and economic burden on families and the society. PACU is the key bridge between the operating room andward. Thus, this unit is the first placewhere changes in patient condition are determined and treated. Early recognition and diagnosis of POD are crucial. A high sensitivity (to detect POD as early as possible) may be achieved with two toolsdNu-DESC and the confusion assessmentmethod. However, it is to be noted that the confusion assessment method has a lower sensitivity when not used by staff specially trained in its use.35

Before the appropriate tools are developed, risk assessment is considered a multidisciplinary responsibility and should be implemented in perioperative clinical pathways.9 Physicians, anesthesia providers, and nurses jointly assess patient condition dynamically and closely and share a common understanding of delirium. Compared with the inpatient ward, PACU is equipped withmore human resources for recognizing disease changes.When patients are diagnosed with ED, they should not be sent from the PACU to the ward without treatment based on pathogenesis and symptoms.33 This condition is attributed to prolonged duration of delirium and delayed treatment, which may intensify the degen- eration of cognitive functions.20,21

Future Studies on the Relationship Between Certain Factors and POD

A widely accepted model of delirium includes susceptibility factors (patient-related) and predisposing factors (triggering delirium). Development of delirium is due to predisposing and inducing behavior. In the present study, single-factor analysis re- sults showed that significant factors, such as preoperative MMSE score, underlying diseases, ASA classification, surgery duration, and postoperative complications, were excluded in the regression model. This result might be attributed to age and appears to be the primary risk factor of POD among elderly patients. In this study, a small sample size was involved, and a certain limitation was imposed on sample selection. The strong correlation between ED

Table 4 The Result of Logistic Regression Analysis (N ¼ 168)

Variable B SE Wald P OR (95% CI)

Constant term �7.533 1.482 25.831 <.001 0.001 ED 5.970 1.004 35.359 <.001 391.369 (54.708-2799.779) Age 1.422 0.411 11.972 .001 4.147 (1.853-9.283)

SE, standard error; OR, odds ratio; 95% CI, 95% confidence interval; ED, emergence delirium.

and POD influenced the inclusion of other variables in the regres- sion equation. Studies have indicated that hypothermia during re- covery period,36 hypoglycemia caused by oral hypoglycemic agents,37 and emergency operation38 are influencing factors of POD. However, evidence is insufficient to verify their effects on the incidence of POD. Future research is needed to expand the sample population.

Limitation

This study involves certain limitations. This study is a single- center observational research and focused only on postoperative elderly patients. The sample size is relatively small and based on convenient sampling. Future studies should expand sample breadth and depth to enhance the validity of research results. For the pain scoring tool, visual simulation scoring might present bias as elderly patients might be short of calibration of coordinate po- sitions. At present, no absolute objective pain assessment tool is available. For the delirium assessment tool, NU-DESC is not the gold diagnosis standard of delirium and cannot completely detect delirium events. However, rather than affecting our findings, this condition increased the possibility that ED was associated with POD 1 to 5 days after surgery (if false-negative results exist). For anesthetics, whether our findings are related to the drug used or whether they are applicable for other types of anesthetics remain unclear. However, this study provides guidance for the definition of a strong new predictive factor of POD. Meanwhile, the existence of ED can also be used as a reference index for brain function recovery and functional reserve during perioperative period.

Relevance to Clinical Practice

The survey found that a significant proportion of elderly pa- tients emerge delirious in PACU. Most of the patients who devel- oped delirium in the next 5 days had experienced ED. This study suggests the need for structured delirium monitoring in the PACU to identify patients potentially at risk for the POD. Once patients have developed delirium during the recovery process, this infor- mation should be included during handoff to postoperative care. Therefore, appropriate preventive measures should be taken promptly to minimize the adverse consequences to patients. Moreover, it canmaximize the use of limitedmedical resources and reduce the expenditure of medical costs.

Conclusions

The indications of delirium among patients in PACU should be considered an abnormal process during recovery period. On the contrary, the medical team shall determine these indicators, inte- grate them into nursing measures, and provide corresponding feedback and suggestions during delivery to theward. Accurate and timely assessment of delirium can effectively guide the treatment and rehabilitation decisions concerning POD, thereby preventing adverse outcomes to the maximum extent.20,21,23,32 The Hospital Elder Life Program (HELP) is an innovative caring mode that is widely proven to prevent delirium among aged patients. HELP was created based on the medical environment and cultural back- ground in Europe and United States.39 With limited medical re- sources, medical system, and traditional practices in China, the implementation of HELP in this country requires clinical tests, continuous verification, and improvement based on large samples after localization.40 Compared with other developed countries, China features inadequate nursing resources, nursing overload, and lacks time for prevention and monitoring of delirium. Existing re- sources cannot be implemented or are inadequate to provide early

Huang et al. / Journal of PeriAnesthesia Nursing 35 (2020) 478e483 483

intervention during hospitalization. Extremely early delirium dur- ing anesthesia recovery period can be used as an entry point for intervention initiation and implementing concentrated strategic process of delirium intervention. Primary attention should be paid to aged patients with ED to relieve their clinical symptoms and rapidly obtain the best long-term prognosis. Nonpharmaceutical therapy is frequently applied to treatment of elderly patients suffering from ED. Pathogenic factors of delirium, such as pain, sleep disorder, malnutrition, or infection, are recognized and managed. Behavior restriction or physical restraints can be applied to patients with risky behavior to prevent extubation by accident and other risks. However, considering that physical restraints have been identified as a cause of delirium, they should be limited to PACU and their contribution to delirium in the postoperative period. Furthermore, attention shall be given to real-time assess- ment of cognitive functions of patients to immediately relieve constraints.41,42

Acknowledgments

Thanks are due to Dr Fan (Shanghai Maritime University) for assistance with the valuable and enlightening discussion. We sincerely thank all the investigation nurses and patients who participated in this survey.

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