Acute postoperative delirium: definitions, incidence, recognition, and interventions

Emergence agitation: current knowledge and unresolved questions

Emergence agitation (EA), also referred to as emergence delirium, can have clinically significant consequences. The mechanism of EA remains unclear. The proposed risk factors of EA include age, male sex, type of surgery, emergency operation, use of inhalational anesthetics with low blood-gas partition coefficients, long duration of surgery, anticholinergics, premedication with benzodiazepines, voiding urgency, postoperative pain, and the presence of invasive devices. If preoperative or intraoperative objective monitoring could predict the occurrence of agitation during emergence, this would help to reduce its adverse consequences. Several tools are available for assessing EA. However, there are no standardized clinical research practice guidelines and its incidence varies considerably with the assessment tool or definition used. Total intravenous anesthesia, propofol, μ-opioid agonists, N-methyl-D-aspartate receptor antagonists, nefopam, α2-adrenoreceptor agonists, regional analgesia, multimodal analgesia, parent-present induction, and preoperative education for surgery may help in preventing of EA. However, it is difficult to identify patients at high risk and apply preventive measures in various clinical situations. The risk factors and outcomes of preventive strategies vary with the methodologies of studies and patients assessed.This review discusses important outcomes of research on EA and directions for future research.

Premedication with dexmedetomidine to reduce emergence agitation: a randomized controlled trial

Background

Nasal bone fracture is the most common type of facial fracture, and the high incidence of severe emergence agitation occurring after closed reduction of the nasal bone fracture can be challenging to manage. The purpose of this trial was to evaluate whether pre-operative administration of dexmedetomidine is effective in reducing the incidence and severity of emergence agitation in adults undergoing closed reduction of nasal bone fractures.

Methods

In this randomized controlled trial, 90 patients who were scheduled to undergo closed reduction of a nasal bone fracture were prospectively included and were randomly assigned to either the control group (n = 45; 0.9% saline infusion) or the dexmedetomidine group (n = 45; 1 μ/kg over 10 min, pre-operatively). The primary endpoint was Aono’s four-point scale scores after anesthesia. The recovery time and numeric rating scale score were assessed as secondary endpoints.

Results

Aono’s four-point scale scores were lower in the dexmedetomidine group than in the control group (median: 1 [1] vs. 1 [1, 2], 95% confidence interval of difference: 0.01 to 0.02, P = 0.02). The number, severity, and duration of agitation episodes were significantly lower in the dexmedetomidine group than in the control group. Furthermore, the number of patients exhibiting intraoperative movement was lower in the dexmedetomidine group.

Conclusions

Pre-operative administration of dexmedetomidine demonstrated several significant benefits, such as a lower incidence of emergence agitation, reduced agitation severity, and a shorter duration of agitation. Additionally, we observed more stable maintenance of intraoperative anesthesia with less movement during the surgery.

Trial registration

Identifier: KCT0000585 (registration date: 12–19- 2012).

Emergence delirium following sevoflurane anesthesia in adults: prospective observational study

Background and objectives

Emergence delirium after general anesthesia with sevoflurane has not been frequently reported in adults compared to children. This study aimed to determine the incidence of emergence delirium in adult patients who had anesthesia with sevoflurane as the volatile agent and the probable risk factors associated with its occurrence.

Design & methods

A prospective observational study was conducted in adult patients who had non-neurological procedures and no existing neurological or psychiatric conditions, under general anesthesia. Demographic data such as age, gender, ethnicity and clinical data including ASA physical status, surgical status, intubation attempts, duration of surgery, intraoperative hypotension, drugs used, postoperative pain, rescue analgesia and presence of catheters were recorded. Emergence delirium intensity was measured using the Nursing Delirium Scale (NuDESC).

Results

The incidence of emergence delirium was 11.8%. The factors significantly associated with emergence delirium included elderly age (>65) (p = 0.04), emergency surgery (p = 0.04), African ethnicity (p = 0.01), longer duration of surgery (p = 0.007) and number of intubation attempts (p = 0.001). Factors such as gender, alcohol and illicit drug use, and surgical specialty did not influence the occurrence of emergence delirium.

Conclusions

The incidence of emergence delirium in adults after general anesthesia using sevoflurane is significant and has not been adequately reported. Modifiable risk factors need to be addressed to further reduce its incidence.

A transient cortical state with sleep-like sensory responses precedes emergence from general anesthesia in humans

During awake consciousness, the brain intrinsically maintains a dynamical state in which it can coordinate complex responses to sensory input. How the brain reaches this state spontaneously is not known. General anesthesia provides a unique opportunity to examine how the human brain recovers its functional capabilities after profound unconsciousness. We used intracranial electrocorticography and scalp EEG in humans to track neural dynamics during emergence from propofol general anesthesia. We identify a distinct transient brain state that occurs immediately prior to recovery of behavioral responsiveness. This state is characterized by large, spatially distributed, slow sensory-evoked potentials that resemble the K-complexes that are hallmarks of stage two sleep. However, the ongoing spontaneous dynamics in this transitional state differ from sleep. These results identify an asymmetry in the neurophysiology of induction and emergence, as the emerging brain can enter a state with a sleep-like sensory blockade before regaining responsivity to arousing stimuli.

General anesthesia is essential to modern medicine. It allows physicians to temporarily keep people in an unconscious state. When infusions of the anesthetic drug stop, patients gradually recover consciousness and awaken, a process called emergence. Previous studies using recordings of electrical activity in the brain have documented spontaneous changes during anesthesia. In addition, the way the brain responds to sounds or other stimulation is altered. How the brain switches between the anesthetized and awake states is not well understood.

Studying the changes that happen during emergence may help scientists learn how the brain awakens after anesthesia. A key question is whether the changes that occur during emergence are the reverse of what happens when someone is anesthetized, or whether it is a completely different process. Knowing this could help clinicians monitoring patients under anesthesia, and help scientists understand more about how the brain transitions into the awake state.

Now, Lewis et al. show that people go through a sleep-like state right before awakening from anesthesia-induced unconsciousness. In the experiments, recordings were made of the electrical activity in the brains of people emerging from anesthesia. One set of recordings was taken in people with epilepsy, who had electrodes implanted in their brains as part of their treatment. Similar recordings of brain electrical activity during emergence were also made on healthy volunteers using electrodes placed on their scalps. In both groups of people, Lewis et al. documented large changes in electrical activity in the brain’s response to sound in the minutes before emergence.

These patterns of electrical activity during emergence were similar to those seen in patients during a normal stage of sleep (stage 2). Patients who were about to wake up from general anesthesia had suppressed brain activity in response to sounds, such as their name. Moreover, this sleep-like state happened only during emergence, indicating it is a distinct process from going under anesthesia. The experiments also suggest that the brain may use a common process to wake up after sleep or anesthesia. More studies may help scientists understand this process and how to better care for patients who need anesthesia.

Association of pre-operative medication use with post-operative delirium in surgical oncology patients receiving comprehensive geriatric assessment

BACKGROUND

Older patients undergoing surgery tend to have a higher frequency of delirium. Delirium is strongly associated with poor surgical outcomes. This study evaluated the association between pre-operative medication use and post-operative delirium (POD) in surgical oncology patients receiving comprehensive geriatric assessment (CGA).

METHODS

A total of 475 patients who were scheduled for cancer surgery and received CGA from January 2014 to June 2015 were included. Pre-operative medication review through CGA was conducted on polypharmacy (≥5 medications), delirium-inducing medications (DIMs), fall-inducing medications (FIMs), and potentially inappropriate medications (PIMs). POD was confirmed by psychiatric consultation, and DSM-V criteria were used for diagnosing delirium. The model fit of the prediction model was assessed by computing the Hosmer-Lemeshow goodness-of-fit test. Effect size was measured using the Nagelkerke R(2). Discrimination of the model was assessed by an analysis of the area under receiver operating curve (AUROC).

RESULTS

Two models were constructed for multivariate analysis based on univariate analysis; model I included dementia and DIM in addition to age and sex, and model II included PIM instead of DIM of model I. Every one year increase of age increased the risk of POD by about 1.1-fold. DIM was a significant factor for POD after adjusting for confounders (AOR 12.78, 95 % CI 2.83-57.74). PIM was also a significant factor for POD (AOR 5.53, 95 % CI 2.03-15.05). The Hosmer-Lemeshow test results revealed good fits for both models (χ(2) = 3.842, p = 0.871 for model I and χ(2) = 8.130, p = 0.421 for model II). The Nagelkerke R(2) effect size and AUROC for model I was 0.215 and 0.833, respectively. Model II had the Nagelkerke R(2)effect size of 0.174 and AUROC of 0.819.

CONCLUSIONS

These results suggest that pharmacists' comprehensive review for pre-operative medication use is critical for the post-operative outcomes like delirium in older patients.

Incidence and risk factors of postoperative delirium in elderly patients who underwent laparoscopic surgery for colorectal cancer

BACKGROUND

The reported incidence of postoperative delirium (POD) in elderly patients ranges from 6 to 53 %. Several preoperative and operative factors have been reported as risk factors of POD.

AIM

The aim of this study was to determine the incidence of and risk factors for POD in patients with colorectal cancer who had undergone laparoscopic colorectal resection.

METHODS

A total of 311 consecutive patients aged 75 years and older who underwent laparoscopic surgery for colorectal cancer at our department from January 2008 to December 2013 were classified as delirious group (n = 44) and nondelirious group (n = 267). Short-term outcomes and risk factors for POD were analyzed.

RESULTS

POD was diagnosed in 14.1 % of elderly patients with colorectal cancer. Univariate analysis showed that older age, high American Society of Anesthesiology (ASA) score, performance status >2, low prognostic nutrition index (PNI), past history of delirium or dementia, operative approach, Organ/Space SSI, and cardiac or pulmonary disease were significantly associated with POD. Multivariate logistic regression analysis identified older age, past history of delirium or dementia, operative approach, and Organ/Space SSI as four independent risk factors for POD.

CONCLUSIONS

Our results suggest that the risk of POD is associated with older age, past history of delirium or dementia, operative approach, Organ/Space SSI.

Postanaesthetic emergence agitation in adult patients after general anaesthesia for urological surgery

Objective

To investigate the incidence and risk factors for emergence agitation in the postanaesthetic care unit (PACU), in adult patients undergoing urological surgery.

Methods

Medical records were retrospectively reviewed. Preoperative, intraoperative and postoperative variables were evaluated. Emergence agitation was defined as a Riker sedation–agitation score ≥5. Logistic regression analysis was used to determine independent risk factors for emergence agitation.

Results

Emergence agitation was observed in 48/488 (9.8%) patients. Chronic lung disease (odds ratio [OR] 2.72, 95% confidence interval [CI] 1.03, 7.17), duration of surgery (OR 1.01, 95% CI 1.00, 1.01), history of social drinking (OR 2.48, 95% CI 1.25, 4.93), postoperative pain score (OR 1.32, 95% CI 1.14, 1.53), voiding urgency (OR 2.20, 95% CI 1.01, 4.77) and presence of gastric tube (OR 2.85, 95% CI 1.07, 7.54) were independent risk factors for emergence agitation.

Conclusions

Adequate postoperative pain management and prevention of catheter-related bladder discomfort may be helpful in reducing the incidence of emergence agitation in urology patients.

Cardiovascular and respiratory effects, and quality of anesthesia produced by alfaxalone administered intramuscularly to cats sedated with dexmedetomidine and hydromorphone

The cardiovascular and respiratory effects, and the quality of anesthesia of alfaxalone administered intramuscularly (IM) to cats sedated with dexmedetomidine and hydromorphone were evaluated. Twelve healthy adult cats were anesthetized, with six cats receiving dexmedetomidine (0.01 mg/kg IM) followed by alfaxalone (5 mg/kg IM; group DA) and six receiving dexmedetomidine (0.01 mg/kg IM) plus hydromorphone (0.1 mg/kg IM) followed by alfaxalone (5 mg/kg IM; group DHA). Cardiorespiratory (pulse rate, blood pressure, respiratory rate, saturation of oxygen with hemoglobin, end tidal carbon dioxide partial pressure) and bispectral index (BIS) data were collected every 10 mins for 90 mins starting immediately after intubation. The quality of anesthesia was scored by a blinded researcher at induction and at 5 and 60 mins after extubation. Recovery scores ranged from 1 (prolonged struggling) to 4 (no struggling). There were no clinically significant ( P >0.05) differences in any data between groups or over time. Physiologic parameters were within normal limits for cats at all times. BIS values were consistent with light anesthesia in both groups. However, recovery was prolonged and marked with excitement, ataxia and hyper-reactivity in all cats. Thus, although cardiovascular and respiratory parameters are stable following IM injection of alfaxalone to cats sedated with dexmedetomidine and hydromorphone, recovery is extremely poor and this route of administration is not recommended for anesthesia in cats.

Impaired mobility, ASA status and administration of tramadol are risk factors for postoperative delirium in patients aged 75 years or more after major abdominal surgery

OBJECTIVE

The aim of this prospective study was to determine incidence, duration, and risk factors for postoperative delirium (PD) in elderly patients undergoing major abdominal surgery.

SUMMARY BACKGROUND DATA

The incidence and risk factors of PD after major abdominal surgery in elderly patients are not well documented.

METHODS

From May 2006 to May 2008, 118 patients aged 75 years or more without severe preoperative cognitive dysfunction (mini mental state examination score >10/30) and undergoing major elective abdominal surgery were included. The preoperative geriatric assessment battery consisted of 4 tests evaluating physical (instrumental activities of daily living and timed get up and go test score) and cognitive function (mini mental state examination score), and detecting the presence of an underlying depression (Short-GDS). After the operation, geriatric patients were assessed for PD by the Confusion Assessment Method. Univariate and multivariate analyses were used to determine risk factors for PD.

RESULTS

Overall, PD occurred in 28 patients (24%). Multivariate analysis showed that an American Society of Anesthesiologists status of 3-4 (P = 0.02), impaired mobility (timed get up and go test score >20 seconds) (P = 0.009) and postoperative tramadol administration (P = 0.0009) were risk factors for PD. The mortality rate was 14% in 28 patients with PD and 3.3% in 90 patients without PD (P = 0.051). The morbidity rate was 35.5% in 28 patients with PD and 32% in 90 patients without PD (NS). The mean hospital stay was 19 +/- 11 days for patients with PD and 14 +/- 8 for patients without PD (P = 0.01). Fifteen of 24 (62.5%) surviving patients with PD and 28 of 87 (32%) surviving patients without PD were discharged to geriatric rehabilitation unit (P = 0.007).

CONCLUSIONS

PD is a frequent and severe postoperative event in elderly patients after major abdominal surgery. A perioperative geriatric assessment should be recommended to patients with an American Society of Anesthesiologists status of 3-4 and preoperative impaired mobility to facilitate the management of PD. In these patients, the postoperative administration of tramadol should be avoided.

Risk factors for postoperative delirium in elderly patients with colorectal cancer

AIMS

The aim of this retrospective study is to examine risk factors for postoperative delirium in elderly patients with colorectal cancer.

METHODS

The study subjects were patients aged 71 years and older who underwent open surgery (OS) or laparoscopically assisted surgery (LAS) for colorectal cancer from January 2004 to December 2007. Preoperative evaluation, operative factors, morbidity, and mortality were analyzed using the Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM) and Prognostic Nutritional Index (PNI). Delirium was diagnosed by the Confusion Assessment Method (CAM).

RESULTS

Postoperative delirium was diagnosed in 10.9% of elderly patients with colorectal cancer. Age, American Society of Anesthesiologists (ASA) score, and PNI were significantly higher in patients with delirium than those without (P < 0.05, each). Postoperative delirium occurred more frequently in patients with encephalopathy than in those without (P = 0.003). Logistic regression analysis identified PNI and encephalopathy as two independent risk factors for postoperative delirium.

CONCLUSIONS

Preoperative evaluation of nutritional status is important in elderly patients with colorectal cancer in order to prevent postoperative delirium.

The virtual gateway: opening doors in delirium teaching and learning

Delirium is a common, serious and potentially preventable problem. It is argued here that knowledge and skills for effective assessment and treatment of delirium cannot be considered 'specialist'. Rather, delirium is a problem that requires a healthcare team approach to assessing patients, identifying risks or symptoms and reducing precipitating factors. Research from the preceding decade suggests that the clinical reality is falling short of this ideal with the result that many cases of delirium go undetected and many precipitating factors are not reduced where this is indeed possible. This presents a challenge for the education of nursing and medical students and for the development of qualified staff in practice. The current paper outlines an educational approach, e-learning, which increases access for learners, integrates knowledge and skill development and promotes active, problem-based learning.

Probable risk factors for postoperative delirium in patients undergoing spinal surgery

Postoperative delirium and its risk factors had been widely reported in several kinds of surgeries; however, there is only one known article relative to postoperative delirium in spinal surgery. We retrospectively examined the incidence of postoperative delirium and the probable risk factors in patients undergoing spinal surgery in our hospital, with the same aged non-delirium patients as controls, over a 6-month period. Studies about postoperative delirium were reviewed and referenced for variable factors collecting in our study. T tests, chi(2) test and logistic regression analysis were performed to evaluate the various factors related to postoperative delirium. A total of 18 patients (3.3%), all of them were aged 54 years or older, had postoperative delirium after surgery. Patients without postoperative delirium aged 54 years or older served as the control group. The percentage of patients older than 65 years (P = 0.003), with comorbid diseases such as diabetes mellitus (P = 0.042) or central nervous system disorders (P = 0.013), with a surgical history (P = 0.028) in delirium group was larger than the control group. The absolute number of medications being taken before the operation in the delirium patients was also more than the control group (P = 0.000). The percentage of patients transfused with 800 mL or more blood was also larger (P = 0.024) in delirium group was larger than the control group. Logistic regression analysis showed that central nervous system disorder (OR 6.480), surgical history (OR 3.499), age older than 65 years (OR 3.390), diabetes mellitus (OR 2.981), transfused 800 mL or more blood (OR 2.537), and hemoglobin less than 100 g/L (OR 0.281) were significantly related to the occurrence postoperative delirium. Our findings suggest that postoperative delirium in spinal surgery can also occurred in younger patients and with an acceptable incidence in total. The risk for postoperative delirium is multifactorial. More prospective research is necessary in order to evaluate these and other risk factors in greater detail.

Prognostic factors for mortality among patients above the 6th decade undergoing non-cardiac surgery: cares--clinical assessment and research in elderly surgical patients

PURPOSE

To ascertain perioperative morbimortality and identify prognostic factors for mortality among patients > or = 55 years who undergo non-cardiac surgery.

METHODS

A retrospective cohort of 403 patients relating to perioperative morbidity-mortality. Data were collected from a standardized protocol on gender, age, comorbidities, medications used, smoking, alcohol abuse, chronic use of benzodiazepine, nutritional status, presence of anemia, activities of daily living, American Society of Anesthesiology classification, Detsky's modified cardiac risk index--American College of Physicians, renal function evaluation, pulmonary risk according to the Torrington scale, risk of thromboembolic events, presence of malignant disease and complementary examinations.

RESULTS

The mean age of the subjects was 70.8 +/- 8.1 years. The "very old" (> or =80 years) represented 14%. The mortality rate was 8.2%, and the complication rate was 15.8%. Multiple logistic regression showed that a history of coronary heart disease (OR: 3.75; p=0.02) and/or valvular heart disease (OR: 31.79; p=0.006) were predictors of mortality. The American Society of Anesthesiology classification was shown to be the best scale to mark risk (OR: 3.01; p=0.016). Nutritional status was a protective factor, in which serum albumin increases of 1 mg/dl decreased risk by 63%.

DISCUSSION

The results indicate that serum albumin, coronary heart disease, valvular heart disease and the American Society of Anesthesiology classification could be prognostic predictors for aged patients in a perioperative setting. In this sample, provided that pulmonary, cardiac and thromboembolic risks were properly controlled, they did not constitute risk factors for mortality. Furthermore, continuous effort to learn more about the preoperative assessment of elderly patients could yield intervention possibilities and minimize morbimortality.

Pathophysiology of delirium in the intensive care unit

Delirium, or acute brain dysfunction, is a life-threatening global disturbance in cognitive functioning that frequently manifests in critically ill patients. This review examines the current status of knowledge regarding the pathophysiology of delirium in the ICU, in particular, evaluating the role of iatrogenic factors such as sedatives and analgesic administration in brain dysfunction. This hypothesis is considered along with several other plausible mechanisms of ICU delirium, including sepsis, postoperative cognitive dysfunction, and changes in biomarkers and neurotransmitters. The review concludes by highlighting potential future directions in molecular genetics for the elucidation of delirium and its long-term consequences.

Medical complications of surgical treatment of adult spinal deformity and how to avoid them

STUDY DESIGN

Review article of medical complications related to adult spinal deformity surgery.

OBJECTIVE

To identify medical complications related to surgery for adult spinal deformity and suggest ways to minimize their occurrence and to avoid them.

SUMMARY OF BACKGROUND DATA

Medical complications are a major consideration in adult spinal deformity surgery. Few studies have been done to identify the medical complication rate in relation to these procedures.

METHODS

We review the literature pertaining to medical complications regarding spinal deformity surgery.

RESULTS

Urinary tract infections are the most frequently seen complication. Additionally, pulmonary complications are the most common life-threatening complication. Medical complications are a frequent occurrence with adult deformity spinal surgery.

CONCLUSIONS

Awareness of the presentation, treatment, and prevention of medical complications of deformity surgery may allow minimization of their occurrence and optimize treatment should they occur.

Emergence delirium in adults in the post-anaesthesia care unit

BACKGROUND

Emergence delirium in the post-anaesthesia care unit (PACU) is poorly understood. The goal of this prospective study was to determine frequency and risk factors of emergence delirium in adults after general anaesthesia.

METHODS

In this prospective study, 1,359 consecutive patients were included. Contextual risk factors and occurrence of delirium according to the Riker sedation scale were documented. Groups were defined for the analysis according to the occurrence or not of agitation, then after exclusion of patients with preoperative anxiety and neuroleptics, or both, and antidepressants or benzodiazepines treatments.

RESULTS

Sixty-four (4.7%) patients developed delirium in the PACU, which can go from thrashing to violent behaviour and removal of tubes and catheters. Preoperative anxiety was not found to be a risk factor. Preoperative medication by benzodiazepines (OR=1.910, 95% CI=1.101-3.315, P=0.021), breast surgery (OR=5.190, 95% CI=1.422-18.947, P=0.013), abdominal surgery (OR=3.206, 95% CI=1.262-8.143, P=0.014), and long duration of surgery increased the risk of delirium (OR=1.005, 95% CI=1.002-1.008, P=0.001), while a previous history of illness and long-term treatment by antidepressants decreased the risk (respectively, OR=0.544, 95% CI=0.315-0.939, P=0.029 and OR=0.245, 95% CI=0.084-0.710, P=0.010).

CONCLUSIONS

Preoperative benzodiazepines, breast and abdominal surgery and surgery of long duration are risk factors for emergence delirium.

Nurses' diagnoses and treatment decisions regarding care of the agitated child

Postoperative agitation has many potential etiologies and remains a significant clinical issue in the pediatric PACU setting. Caring for the agitated child requires a thorough assessment and calls for targeted interventions. This observational study evaluated nurses' diagnoses and treatment decisions regarding care of the agitated child. Nurses were observed during their care of 194 agitated children over a 3-month period. Pain and anxiety were the most commonly identified sources of agitation in the pediatric PACU setting (27% and 25% of cases, respectively), and nurses' targeted, primary interventions for these problems were fairly effective (48% and 67% effective, respectively). Anesthesia-induced agitation was less often identified as the etiology (11%), and primary interventions were more varied and less effective (38%). Physiologic abnormalities were identified as the source for agitation in only 3 cases, but went unrecognized for an extended period in 2 children. Results of this study underscore the complexity of assessment and treatment decisions when caring for agitated children. A decision algorithm based on this study is described as a potential aid toward differentiation of agitation and appropriate intervention.

Postoperative delirium in elderly patients after major abdominal surgery

Background

The aim of this study was to investigate the occurrence of postoperative delirium (POD) in elderly patients undergoing major abdominal surgery and to identify factors associated with delirium in this population.

Methods

Data were collected prospectively from 51 patients aged 65 years or more. Delirium was diagnosed by the Confusion Assessment Method and from the medical records. The Mini Mental State Examination (MMSE) was used to identify cognitive impairment.

Results

POD occurred in 26 of 51 patients. Delirium lasted for 1–2 days in 14 patients (short POD group) and 3 days or more in 12 patients (long POD group). The latter patients had significantly greater intraoperative blood loss and intravenous fluid infusion, a higher rate of postoperative complications, a lower MMSE score on postoperative day 4 and a longer hospital stay than patients without POD. Patients in the short POD group were significantly older than those in the long POD group and those who did not develop delirium.

Conclusion

Approximately half of the elderly patients in this study developed POD. Bleeding was found to be an important risk factor for delirium.