JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (20) Citing Articles via Google Scholar Google Scholar Articles by Vaurio, L. E. Articles by Leung, J. M. Search for Related Content PubMed PubMed Citation Articles by Vaurio, L. E. Articles by Leung, J. M. Related Collections Postanesthetic Care Unit Pain Pharmacology

---

GENERAL ARTICLES

Postoperative Delirium: The Importance of Pain and Pain Management

Linnea E. Vaurio, BA^*, Laura P. Sands, PhD, Yun Wang, PhD, E. Ann Mullen, BSc^*, and Jacqueline M. Leung, MD, MPH^*

*Department of Anesthesia and Perioperative Care, University of California, San Francisco; and School of Nursing, Center on Aging and the Life Course and Department of Statistics, Purdue University, West Lafayette, Indiana Current position for Y.W.: Staff statistician, Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA 15213

Address correspondence to Jacqueline M. Leung, MD, MPH, University of California, San Francisco, Department of Anesthesia and Perioperative Care, 521 Parnassus, San Francisco, CA 94143-0648. Address e-mail to leungj{at}anesthesia.ucsf.edu

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Postoperative delirium is common in geriatric patients. Few studies have examined events in the postoperative period that may contribute to the occurrence of postoperative delirium. We hypothesized that postoperative delirium is related to postoperative pain and/or pain management strategy. Patients aged 65 years who were scheduled for major noncardiac surgery were studied. A structured interview was conducted preoperatively and for the first 3 postoperative days to determine the presence of delirium using the Confusion Assessment Method. The method of postoperative pain management, as well as pre- and postoperative medications for the first 3 days, was collected. Pre- and postoperative pain at rest and with movement was recorded using the Visual Analog Scale. Three hundred thirty-three patients, with a mean age of 74 ± 6 years, were studied. After surgery, 46% of patients developed postoperative delirium. By multivariate logistic regression, age (odds ratio [OR], 2.5; 95% confidence interval [CI] 1.5 to 4.2), moderate (OR, 2.2; 95% CI 1.2 to 4.0) and severe (OR, 3.7; 95% CI 1.5 to 9.0) preoperative resting pain, and increase in level of pain from baseline to postoperative day one (OR, 1.1; 95% CI 1.01 to 1.2) were independently associated with a greater risk for the development of postoperative delirium. In contrast, patients who used oral opioid analgesics as their sole means of postoperative pain control were at decreased risk of developing delirium in comparison with those who used opioid analgesics via IV patient-controlled analgesia technique (OR, 0.4; 95% CI 0.2 to 0.7). These results validate our hypothesis that pain and pain management strategies are important factors related to the development of postoperative delirium in elderly patients.

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Postoperative delirium occurs in 10%–60% of patients, and the rate of occurrence is most frequent in those who are older (1–8). Given the projected aging of the population, which will result in more elderly persons presenting for surgery, postoperative delirium is likely to continue to be a prevalent condition.

Previous studies have examined the relationship between patient-related factors, surgical factors and postoperative delirium (1,6,8–11). Few studies have examined events in the postoperative period that may contribute to the occurrence of postoperative delirium. Two related and possibly modifiable factors in the postoperative period are postoperative pain and analgesic medications. Although prior studies suggest that postoperative pain and analgesia are associated with postoperative delirium (3,12), the relative importance of these two factors on postoperative delirium remains unclear. For example, Lynch et al. (3) studied patients 50 years of age undergoing elective noncardiac surgery and reported that pain occurring at rest in the postoperative period was associated with postoperative delirium. In contrast, Marcantonio et al. (12) reported that pain did not increase the risk of postoperative delirium. Because postoperative pain management techniques have changed substantially in recent years, an examination of the association of current pain management strategy on the incidence of delirium is indicated. Therefore, we investigated whether the method of postoperative pain management, medication types, and the severity of postoperative pain may affect the occurrence of postoperative delirium, when controlling for other covariates. We hypothesized that both postoperative pain and pain management method had an independent association with the development of postoperative delirium.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Patient Recruitment
The study was approved by the IRB for human research, at the University of California, San Francisco, and informed consent was obtained preoperatively from each study patient. The study was conducted from 2001 to 2004 at the University of California, San Francisco Medical Center, and the patients included are a subset of a continuing investigation of the pathophysiology of postoperative delirium in elderly surgical patients. The inclusion criteria were consecutive English-speaking patients 65 years of age who were scheduled for major elective noncardiac surgery requiring anesthesia and who were expected to remain in the hospital for more than 48 h after surgery. Excluded were patients who did not provide or were incapable of providing informed consent.

Timing of Patient Assessments
The same trained research assistant conducted three patient interviews in person. The preoperative interview typically occurred <48 h before surgery in the preoperative clinic and included the assessment of depressive symptoms, medical history focusing on neurological status, and assessment of patients' cognitive status, pain, and functional status. The two postoperative interviews, which focused on the assessment of cognitive status, were conducted in the patients' hospital rooms approximately 24 and 48 h after surgery, generally between the hours of 9 am and noon.

Measurement of Pain
Research assistants recorded pain levels reported by patients during structured interviews using a verbal version of the Visual Analog Scale (VAS), in which a rating of zero corresponds to no pain, ratings of 1–4 indicate moderate pain, and ratings of 5–10 correspond to severe pain (13). Preoperatively and on postoperative Day 1 (approximately 24 hours after surgery) and postoperative Day 2 (approximately 48 hours after surgery), patients were asked to rate their pain at rest and pain with movement. We calculated a ‘change in pain score,‘ which was the difference between the preoperative (baseline, nonsurgical) resting VAS score and postoperative resting VAS score. This score provides an estimate of whether the postoperative pain was greater than preoperative pain. A clinically significant change was considered an increase of two or more points on the 11-point VAS (14).

Assessment of Postoperative Pain Management
Postoperative pain management was not controlled by the study design and was determined by the attending physicians. The method of postoperative pain management (patient-controlled analgesia [PCA], neuraxial analgesia [epidural or intrathecal], orally administered opioid analgesics, or a combination) was recorded from chart review. In addition, the type and daily doses of all commonly used opioid analgesics (morphine sulfate, fentanyl, and hydromorphone) were recorded for the first 3 postoperative days. The type of all other less commonly used analgesics and all medications with central nervous system (CNS) effects were also recorded for the first 3 postoperative days. For analytic purposes, these medications were classified as antidepressants, benzodiazepines, nonbenzodiazepine tranquilizers, other opioid analgesics, antihistamines, or nonopioid analgesics.

Assessment of Delirium
During the three interviews, trained interviewers determined the presence of delirium using the Confusion Assessment Method (CAM) (15). All assessments of postoperative delirium were validated by a second investigator (LPS). We defined the onset of delirium as the patient meeting CAM criteria for delirium on either the first or second postoperative day assessments.

Assessment of Covariates
The potential covariates associated with postoperative delirium were selected based on the feasibility of measurement in the clinical setting and their possible influence on delirium. A structured interview was conducted preoperatively to assess demographics, education level, alcohol intake, and preoperative living arrangement. Cognitive status was assessed preoperatively using the Telephone Interview for Cognitive Status (TICS), which can be administered in person or over the phone (16). The TICS is adapted from the Mini Mental Status Examination. The Geriatric Depression Scale was administered to determine the presence of preoperative depressive symptoms (17). Functional status was measured using the Activities of Daily Living (18) and the Instrumental Activities of Daily Living (19). Medical record review was conducted to obtain information about the type and number of coexistent medical conditions. The severity of preoperative coexistent conditions was measured using the Charlson Comorbidity index (20). Other perioperative data obtained from chart review included the type of surgery, the ASA classification (which incorporates the number and severity of preoperative comorbid conditions [21]), and the type of anesthesia (general, regional or combined). Surgical risk was estimated using the guidelines from the American College of Cardiology and American Heart Association update for the perioperative cardiovascular evaluation for noncardiac surgery, which takes into consideration the type and duration of surgery and intraoperative blood loss (22).

Statistical Methods
Bivariate associations were tested using ² tests for categorical variables and Mantel-Haenszel ² tests for trend were used for ordinal variables. A multivariate logistic regression analysis was conducted to determine the independent effect of postoperative pain and analgesia after adjusting for variables that were associated with onset of delirium in bivariate analyses with a P value of 0.20 or less. Variables were eliminated using stepwise elimination technique. The final model consisted of variables associated with delirium with a P value of <0.05.

	Results

Top Abstract Introduction Methods Results Discussion References

 
Three hundred thirty-three patients were included in the study. The mean age of the patients was 74 ± 6 years (range, 65–96 years). Patient demographic information, baseline cognitive function, and functional status are shown in Table 1. The type of surgery is described in Table 2.

Preoperative chronic pain was prevalent: 27.3% of patients reported moderate pain at rest and 17% reported severe pain at rest, whereas 63.3% experienced moderate-to-severe pain with movement. Most patients reported increased pain postoperatively. On postoperative Day 1, 44.3% had increased pain at rest, and 45.5% had increased pain with movement. On postoperative Day 2, 32.7% of patients reported increased pain at rest, and 48.1% reported increased pain with movement. Table 3 further illustrates the temporal changes in reported pain levels.

Before surgery, 23% of patients were taking opioid analgesics, 11% used benzodiazepines, and 9% used antidepressants. During the first 2 postoperative days, 23.0% of patients received benzodiazepines, 11.4% received antidepressants, and 32.2% of patients received antihistamines. The type of opioid analgesics administered to patients postoperatively included: hydromorphone in 46.3% of patients, morphine sulfate in 33.4%, and fentanyl in 22.6%. Orally administered opioid analgesics, including hydrocodone and acetaminophen, oxycodone and acetaminophen, codeine and acetaminophen, or propoxyphene and acetaminophen, were used postoperatively by 64.6% of patients.

For postoperative pain control, 49% of patients received opioid analgesics via IV PCA. Neuraxial analgesia was used by 14% of patients, and 18% of patients had a combination of PCA and neuraxial methods. The remainder, 19%, had only orally administered analgesics.

After surgery, 46% of patients developed delirium. Significant bivariate associations of demographic, medical and intraoperative factors with postoperative delirium as measured by the CAM (P < 0.05) were: age, gender, Instrumental Activities of Daily Living dependence, low TICS score, high Geriatric Depression Scale score, low education, ASA classification >2, and surgery type. Race, Activities of Daily Living dependence, alcohol intake, and anesthesia technique were not significantly associated with delirium. Bivariate analysis of pain and classes of medications showed preoperative pain at rest, preoperative pain with movement, pain at rest on postoperative Day 1, mode of postoperative analgesia, use of oral narcotics on postoperative Day 1, use of benzodiazepines postoperatively, and use of miscellaneous category CNS action medications to be associated with delirium (Table 5).

By multivariate logistic regression, in addition to age (odds ratio [OR], 2.5; 95% confidence interval [CI] 1.5 to 4.2), moderate (OR, 2.2; 95% CI 1.2 to 4.0) to severe preoperative resting pain (OR, 3.7; 95% CI 1.5 to 9.0) and increase in level of pain from baseline to postoperative day one (OR, 1.1; 95% CI 1.01 to 1.2) were independently associated with a greater risk for the development of postoperative delirium after considering other factors that are related to the onset of delirium (Table 6). In contrast, patients who used oral opioid analgesics as their sole means of postoperative pain control were at decreased risk of developing delirium compared with patients using opioid analgesics via IV PCA technique (OR, 0.4; 95% CI 0.2 to 0.7).

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
Our study found that postoperative pain and pain management strategies are independently associated with the development of postoperative delirium. Although methods of postoperative pain relief have been studied, our study simultaneously integrates previously associated risk factors: the impact of methods of postoperative analgesia, medication types, and pain levels on postoperative delirium and demographic, medical, surgical, and cognitive risk factors in a consecutive large cohort of elderly surgical patients.

Our study uniquely demonstrated that both the presence of postoperative pain and increased pain postoperatively are independent predictors of postoperative delirium. Furthermore, there was an ordered relationship between levels of preoperative pain and the risk for the development of postoperative delirium; severe preoperative pain was associated with greater odds of developing delirium than was moderate pain. This finding highlights the importance of considering and perhaps treating both preoperative chronic pain levels and postoperative pain levels.

Another important factor found to be associated with postoperative delirium is the method of postoperative pain relief. Our results demonstrate that IV PCA and neuraxial analgesics conferred equal risk in the development of delirium, a finding corroborated by other studies (3,5,12). This finding is rather unexpected, because the doses of opioid analgesics delivered neuraxially are typically smaller than that administered IV. In addition, local anesthetics are typically infused in the epidural catheter, further decreasing the doses of opioid used. These results suggest that factors other than doses of opioid analgesics (such as the adequacy of pain control) may play a more important role in the development of postoperative delirium. In contrast, our study is one of the first to report that patients who received oral opioid analgesics as their primary method of postoperative pain management were at decreased risk for developing delirium compared with those receiving PCA. Opioid analgesics administered orally may result in a lower blood level of the drug because of the first-pass effect compared with IV-administered narcotics, which may directly cross the blood-brain barrier. Alternatively, the use of oral narcotics for postoperative analgesia may be a marker for a less painful state. However, this result remains significant even when adjusting for the level of pain. Although differences in patient population may account for the difference in findings compared with that reported by previous studies, our present results suggest that a randomized trial is necessary to further delineate the precise role of a postoperative method for postoperative pain management and postoperative delirium.

Reported incidence of delirium in previous studies has ranged from 9% to 70% (2,5,6,11,23–25). Our finding of a 46% incidence of postoperative delirium (35.3% postoperative day 1, 33.0% day 2) is consistent with several prior estimates (36% [7], 39.2% [8], and 42% [26]) but more frequent than that reported by others (9% [10] and 9.4% [3]). Patient population and methodological factors may have accounted for the different rates of delirium. Furthermore, patients in our study were older, with a mean age of 74 ± 6.2 years. In contrast, the mean ages reported by several prior studies were from 55 to 66 years (3,4,7). Because age is a powerful independent predictor of postoperative delirium, we have probably captured a patient population that is at higher risk. In addition to patient demographic factors, the timing of measurement may have accounted for the difference in the reported incidence. We examined the presence of delirium in the early postoperative period (Days 1 to 3), whereas others have examined delirium in a later period (6,11). In addition, we used the same investigator in the daily structured interview of study subjects. This practice is likely to have increased the sensitivity of detecting a change in cognitive status, which is one critical feature of delirium diagnosis.

Several factors found to be significant predictors of postoperative delirium in previous studies (functional status, alcohol intake, depressive symptoms, pre-existing cognitive impairment, postoperative resting pain) (1,3,5,7,9,27) were found to be significant predictors in bivariate analyses. Although these factors were important and were included in our analysis, once postoperative pain and analgesia were considered, they did not remain as independent predictors of postoperative delirium in the multivariate model. Our findings suggest that pain and the method of postoperative pain management have a greater impact on the development of postoperative delirium than preoperative demographic (excluding age) or cognitive factors. Furthermore, we found that the type of anesthesia (general versus regional) was not a significant factor associated with postoperative delirium, as did previous studies (6,10,28). In addition, other factors found to be predictive of postoperative delirium on bivariate analysis such as ASA classification, surgery type, postoperative use of benzodiazepines, and postoperative use of other medications with CNS effects, did not hold true in the final model (Tables 4 and 5).

Only one prior study showed that a specific type of postoperative medication was associated with delirium. Marcantonio et al. (12) found that meperidine was related to the development of postoperative delirium. In contrast, we found that no specific medication type was related to the development of postoperative delirium. However, meperidine was rarely prescribed for patients in our study, reflecting recent clinical practice. We demonstrated that no pre- or postoperative medication (benzodiazepine, anticholinergic, opioid analgesic, etc.) was associated with postoperative delirium. The lack of association with preoperative medications differs from the results of Kudoh et al. (25), who reported that long-term benzodiazepine users had an increased risk of postoperative confusion after orthopedic surgery. However, as stated by the authors, one cannot be sure whether the postoperative confusion was secondary to withdrawal from benzodiazepine, because these patients' customary dose of benzodiazepine was withheld for 72 hours postoperatively when delirium was assessed. Litaker (1) reported that the use of narcotics before admission was a risk factor for postoperative delirium. However, this study did not control for reports of pre- and postoperative pain. It is likely that preoperative use of opioid analgesics is a surrogate marker of pain, further supporting our finding that the adequacy of pain control for both before and after the operation is an important area to target for care improvement.

Potential Limitations
Although we have described an association between pain states and postoperative delirium, we cannot determine the mechanism by which pain is related to postoperative delirium. In addition, the study was not designed to examine the precise temporal relationship of medication effects and postoperative delirium, because we have recorded the use of certain medications on only a daily basis. The relationship between the timing of patient delivered boluses of opioids through PCA or oral analgesics and the onset of symptoms of delirium remains to be determined. Pain scores were collected only once daily, at the time of cognitive assessment by the trained interviewer. In addition, patients with delirium may not effectively communicate verbal VAS scores. However, cognitively impaired patients have been found to be able to use self-report pain scales, and delirious patients do have periods of lucidity during which pain assessment is possible (29). We focused on measuring delirium in the early postoperative period, as subjects in this investigation are included in a larger studying examining perioperative management and delirium. As a result, incidents of later onset delirium may have been missed.

Clinical Implications
Most of the previous research has focused on the association between intraoperative events and postoperative delirium. Our present results appear to support our hypothesis that postoperative events are, in fact, more important than the type of anesthesia (regional versus general), because the latter has no demonstrable relationship with postoperative delirium. Rather, levels of preoperative pain and the postoperative increase in pain levels (as represented by the change in VAS score) are independent predictors of the development of postoperative delirium in elderly surgical patients. These results suggest that elderly surgical patients with substantial preoperative baseline pain should be targeted for more intensive pain control or addition of adjuvant analgesia postoperatively. Furthermore, all of the commonly used opioid analgesics (fentanyl, morphine sulfate, and hydromorphone) have a similar effect on the development of postoperative delirium.

Further research targeting the temporal relationship of medication intake and delirium onset is indicated. In addition, randomized trials of method of postoperative pain management might offer insight into the precise relationship between the adequacy of pain control and its potential effects on cognition.

	Footnotes

 
Supported in part by institutional funds and by National Institutes of Health Grant 1K24-AG00948-05.

Accepted for Publication October 28, 2005.

	References

Top Abstract Introduction Methods Results Discussion References

 

1. Litaker D, Locala J, Franco K, et al. Preoperative risk factors for postoperative delirium. Gen Hosp Psychiatry 2001;23:84–9.[Web of Science][Medline]
2. Dyer C, Ashton C, Teasdale T. Postoperative delirium. A review of 80 primary data-collection studies. Arch Intern Med 1995;155:461–5.[Abstract/Free Full Text]
3. Lynch E, Lazor M, Gellis J, et al. The impact of postoperative pain on the development of postoperative delirium. Anesth Analg 1998;86:781–5.[Abstract]
4. Marcantonio E, Goldman L, Orav E, et al. The association of intraoperative factors with the development of postoperative delirium. Am J Med 1998;105:380–4.[Web of Science][Medline]
5. Williams-Russo P, Urquhart B, Sharrock N, Charlson M. Post-operative delirium: predictors and prognosis in elderly orthopedic patients. J Am Geriatr Soc 1992;40:759–67.[Web of Science][Medline]
6. Williams-Russo P, Sharrock N, Mattis S, et al. Randomized trial of hypotensive epidural anesthesia in older adults. Anesthesiology 1999;91:926–35.[Web of Science][Medline]
7. Schneider F, Bohner H, Habel U, et al. Risk factor for postoperative delirium in vascular surgery. General Hospital Psychiatry 2002;24:28–34.[Web of Science][Medline]
8. Bohner H, Hummel TC, Habel U, et al. Predicting delirium after vascular surgery: a model based on pre- and intraoperative data. Ann Surg 2003;238:149–56.[Web of Science][Medline]
9. Marcantonio ER, Juarez G, Goldman L, et al. The relationship of postoperative delirium with psychoactive medications. Jama 1994;272:1518–22.[Abstract/Free Full Text]
10. Marcantonio ER, Michaels M, Resnick NM. Diagnosing delirium by telephone. J Gen Intern Med 1998;13:621–3.[Web of Science][Medline]
11. Williams-Russo P, Sharrock N, Mattis S, et al. Cognitive effects after epidural vs general anesthesia in older adults. JAMA 1995;274:44–50.[Abstract/Free Full Text]
12. Marcantonio E, Goldman L, Mangione C, et al. A clinical prediction rule for delirium after elective noncardiac surgery. JAMA 1994;271:134–9.[Abstract/Free Full Text]
13. Jensen MP, Karoly P, Braver S. The measurement of clinical pain intensity: a comparison of six methods. Pain 1986;27:117–26.[Web of Science][Medline]
14. Farrar JT, Portenoy RK, Berlin JA, et al. Defining the clinically important difference in pain outcome measures. Pain 2000;88:287–94.[Web of Science][Medline]
15. Inouye S, van Dyke C, Alessi C, et al. Clarifying confusion: the confusion assessment method. Ann Intern Med 1990;113:941–8.[Abstract/Free Full Text]
16. Brandt J, Spencer M, Folstein M. The telephone interview for cognitive status. Neuropsychiatry Neuropsychol Behav Neurol 1988;1:111–7.
17. Brink T, Yesavage J, Lum O, et al. Screening tests for geriatric depression. Clin Gerontol 1982;1:37–43.
18. Katz W, Ford A, Moskokwitz R, et al. Studies of illness in the aged: the index of ADL: a standardized measure of biological and psychosocial function. JAMA 1963;185:914–9.[Abstract/Free Full Text]
19. Lawton M, Brody E. Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist 1969;9:179–86.[Web of Science][Medline]
20. Charlson M, Pompei P, Ales K, MacKenzie C. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chron Dis 1987;40:373–83.[Web of Science][Medline]
21. Longnecker D, Murphy F. Dripps/Eckenhoff/Vandam introduction to anesthesia. 9th ed. Philadelphia: WB Saunders, 1997.
22. ACC/AHA guideline update for the perioperative cardiovascular evaluation for noncardiac surgery—executive summary. A report of the Am College of Cardiology/Am Heart Association Task Force on Practice Guidelines (Committee to update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Anesth Analg 2002;94:1052–64.[Free Full Text]
23. Williams M, Holloway J, Winn M, et al. Nursing activities and acute confusional states in elderly hip-fractured patients. Nursing Res 1979;26:25–35.
24. Marcantonio ER, Flacker JM, Michaels M, Resnick NM. Delirium is independently associated with poor functional recovery after hip fracture. J Am Geriatr Soc 2000;48:618–24.[Web of Science][Medline]
25. Kudoh A, Takase H, Takahira Y, Takazawa T. Postoperative confusion increases in elderly long-term benzodiazepine users. Anesth Analg 2004;99:1674–8.[Abstract/Free Full Text]
26. Sasajima Y, Sasajima T, Uchida H, et al. Postoperative delirium in patients with chronic lower limb ischaemia: what are the specific markers? Eur J Vasc Endovasc Surg 2000;20:132–7.[Medline]
27. Galanakis P, Bickel H, Gradinger R, et al. Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications. Int J Geriatr Psychiatry 2001;16:349–55.[Web of Science][Medline]
28. Rasmussen LS, Johnson T, Kuipers HM, et al. Does anaesthesia cause postoperative cognitive dysfunction? A randomised study of regional versus general anaesthesia in 438 elderly patients. Acta Anaesthesiol Scand 2003;47:260–6.[Web of Science][Medline]
29. Ferrell BA, Ferrell BR, Rivera L. Pain in cognitively impaired nursing home patients. J Pain Symptom Manage 1995;10:591–8.[Web of Science][Medline]

This article has been cited by other articles:

				C. N. Sessler and K. Varney Patient-Focused Sedation and Analgesia in the ICU Chest, February 1, 2008; 133(2): 552 - 565. [Abstract] [Full Text] [PDF]

				V. K. F. Kong and M. G. Irwin Gabapentin: a multimodal perioperative drug? Br. J. Anaesth., December 1, 2007; 99(6): 775 - 786. [Abstract] [Full Text] [PDF]

				S. S. Liu and C. L. Wu Effect of Postoperative Analgesia on Major Postoperative Complications: A Systematic Update of the Evidence Anesth. Analg., March 1, 2007; 104(3): 689 - 702. [Abstract] [Full Text] [PDF]

				T. Ledowski, J. Bromilow, M. J. Paech, H. Storm, R. Hacking, and S. A. Schug Monitoring of skin conductance to assess postoperative pain intensity Br. J. Anaesth., December 1, 2006; 97(6): 862 - 865. [Abstract] [Full Text] [PDF]

				J. D. Markman Gabapentin in the operating room: clear for discharge? Neurology, October 10, 2006; 67(7): 1116 - 1117. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (20) Citing Articles via Google Scholar Google Scholar Articles by Vaurio, L. E. Articles by Leung, J. M. Search for Related Content PubMed PubMed Citation Articles by Vaurio, L. E. Articles by Leung, J. M. Related Collections Postanesthetic Care Unit Pain Pharmacology

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999