Polypharmacy in a general surgical unit and consequences of drug withdrawal

Thirty-day mortality risk associated with the postoperative nonresumption of angiotensin-converting enzyme inhibitors: a retrospective study of the Veterans Affairs Healthcare System

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACE-Is) are a widely used class of cardiovascular medication. However, limited data exist on the risks of postoperative nonresumption of an ACE-I.

OBJECTIVE

To evaluate the factors and 30-day mortality risks associated with the postoperative nonresumption of an ACE-I.

DESIGN

A retrospective cohort study.

SETTING

Veterans Affairs (VA) Healthcare System.

PATIENTS

A total of 294,505 admissions in 240,978 patients with multiple preoperative prescription refills (>3) for an ACE-I who underwent inpatient surgery from calendar years 1999 to 2012.

INTERVENTION

None.

MEASUREMENTS

We classified surgical admissions based upon the timing of postoperative resumption of an ACE-I prescription from the day of surgery through postoperative days 0 to 14 and 15 to 30, and collected 30-day mortality data. We evaluated the relationship between 30-day mortality and the nonresumption of an ACE-I from postoperative day 0 to 14 using proportional hazard regression models, adjusting for patient- and hospital-level risk factors. Sensitivity analyses were conducted using more homogeneous subpopulations and propensity score models.

RESULTS

Twenty-five percent of our cohort did not resume an ACE-I during the 14 days following surgery. Nonresumption of an ACE-I within postoperative day 0 to 14 was independently associated with increased 30-day mortality (hazard ratio: 3.44; 95% confidence interval: 3.30-3.60; P < 0.001) compared to the restart group. Sensitivity analyses maintained this relationship.

CONCLUSIONS

Nonresumption of an ACE-I is common after major inpatient surgery in the large VA Health Care System. Restarting of an ACE-I within postoperative day 0 to 14 is, however, associated with decreased 30-day mortality. Careful attention to the issue of timely reinstitution of chronic medications such as an ACE-I is indicated.

Evidence based development of bedside clinical drug rules for surgical patients

BACKGROUND

Surgical adverse events constitute a considerable problem. More than half of in-hospital adverse events are related to a surgical procedure. Medication related events are frequent and partly preventable. Due to the complexity and multidisciplinary nature of the surgical process, patients are at risk for drug related problems. Consistent drug management throughout the process is needed.

OBJECTIVE

The aim of this study was to develop an evidence-based bedside tool for drug management decisions during the pre- and postoperative phase of the surgical pathway.

SETTING

Tool development study performed in an academic medical centre in the Netherlands involving an expert panel consisting of a surgeon, a clinical pharmacist and a pharmacologist, all experienced in quality improvement.

METHOD

Relevant medication related problems and critical pharmacotherapeutic decision steps in the surgical process were identified and prioritised by a team of experts. The final selection comprised undesirable effects or unintended outcomes related to surgery (e.g. pain, infection) and comorbidity related hazards (e.g. diabetes, cardiovascular diseases). To guide patient management, a list of bedside surgical drug rules was developed using international evidence-based guidelines.

MAIN OUTCOME MEASURE

55 bedside drug rules on 6 drug categories, specifically important for surgical practice, were developed: pain, respiration, infection, diabetes, cardiovascular diseases and anticoagulation.

RESULTS

A total of 29 evidence-based guidelines were used to develop the Bedside Surgical Drug Rules tool. This tool consist of practical tables covering management regarding (1) the most commonly used drug categories during surgery, (2) comorbidities that require dosing adjustments and, (3) contra-indicated drugs in the perioperative period.

CONCLUSION

An evidence-based approach provides a practical basis for the development of a bedside tool to alert and assist the care providers in their drug management decisions along the surgical pathway.

A targeted method for standardized assessment of adverse drug events in surgical patients

OBJECTIVES

This study demonstrates the development, reliability and outcome of a targeted method for standardized assessment of adverse drug events (ADEs) in surgical patients.

METHODS

Initial practice evaluation of this ADE assessment method was carried out in a prospective single centre cohort study. In total, 262 electively admitted surgical patients were included. The surgical trigger tool was applied to patients' medical records by two independent reviewers, and subsequent assessment of causality, severity and preventability of ADEs was carried out by two independent expert panels consisting of a consultant surgeon and a clinical pharmacologist. The surgical trigger tool and causality assessment method were each tested on reliability in a separate group of 50 randomly selected patients using Fleiss and Cohen's kappa statistics and percentages of agreement. Comparison of this method with an existing trigger tool method for ADEs was performed.

RESULTS

Our surgical trigger tool contains 51 triggers. The inter- and intra-rater calculations showed substantial to almost perfect levels of agreement (kappa range 0.71-0.83), with a 97.8-98.5% percentage of agreement. Fair to substantial levels of agreement were calculated for causality, severity and preventability (kappa range 0.38-0.79). The percentages of inter- and intra-rater agreement were 68.9 and 70.5% for causality, 67.0 and 82.0% for severity, and both 98.4% for preventability, respectively. Compared with the existing trigger tool method for ADEs, we found an additional 363 triggers, 18 ADEs (an extra 20%) and 3 preventable ADEs in our surgical cohort.

CONCLUSIONS

This targeted trigger tool for standardized assessment of ADEs in surgical patients shows excellent agreement between reviewers. The assessment of medication-related harm had acceptable agreement. Compared with an existing ADE trigger tool method, the present method found almost 20% extra ADEs. This method can be a useful alternative to existing trigger tool methods, in particular to assess medication safety in surgical patients.

Occurrence and preventability of adverse drug events in surgical patients: a systematic review of literature

BACKGROUND

Adverse drug events (ADEs) are a considerable cause of inhospital morbidity and mortality. Patient flow differs substantially for surgical and nonsurgical patients: surgical patients are subjected to multiple medication changes related to surgical intervention or postoperative care. The objective of this study is to systematically review the occurrence and nature of ADEs in surgical patients. Also, a comparison with nonsurgical patients was made.

METHODS

A search was conducted in Embase and Medline identifying studies that reported observational data on the occurrence and nature of ADEs in surgical hospitalised adult patients. If sufficient data were available, the occurrence of (preventable) ADEs was compared between surgical and nonsurgical patients.

RESULTS

Six studies fulfilled the inclusion criteria. The occurrence of ADEs in surgical patients ranged from 2.0 to 27.7 per 100 admissions, from 4.7 to 8.9 per 1,000 patient days, or involved 8.9% of the patients. Proportions of preventable ADEs in surgical patients were 18% and 54%, described in two studies. A head-to-head comparison of surgical patients and nonsurgical patients was possible for five of six studies. The occurrence of ADEs in nonsurgical patients was significantly higher than in surgical patients in three studies.

CONCLUSIONS

ADEs are a relevant problem in surgical patients and nonsurgical patients, with a high proportion of preventable ADEs. The occurrence of ADEs appears to be higher in nonsurgical patients than in surgical patients. However, studies lack details on the differences in nature of ADEs between hospital populations. To improve medication safety this knowledge is essential.

A population-based study on the association between acute renal failure (ARF) and the duration of polypharmacy

BACKGROUND

Because of the rapid growth in elderly population, polypharmacy has become a serious public health issue worldwide. Although acute renal failure (ARF) is one negative consequence of polypharmacy, the association between the duration of polypharmacy and ARF remains unclear. We therefore assessed this association using a population-based database.

METHODS

Data were collected from the Taiwan National Health Insurance Research Database (NHIRD) from 2003 through 2006. The case group included patients hospitalized for ARF during 2006, but not admitted due to trauma, surgery, burn trauma, car accident, transplantation, or infectious diseases; the control group included patients hospitalized without ARF. The cumulative number of days of polypharmacy (defined as more than 5 prescriptions per day) for 1 year prior to admission was determined, with patients further subdivided into 4 categories: less than 30 days, 31-90 days, 91-180 days, and over 181 days. The dependent variable was ARF, and the control variables were age, gender, comorbidities in patients hospitalized for ARF, stay in ICUs during ARF hospitalization and site of operation for prior admissions within one month of ARF hospitalization.

RESULTS

Of 20,790 patients who were admitted to hospitals for ARF in 2006, 12,314 (59.23 %) were male and more than 60 % were older than 65 years. Of patients with and without ARF, 16.14 % and 10.61 %, respectively, received polypharmacy for 91-180 days and 50.22 % and 24.12 %, respectively, for over 181 days. A statistical model indicated that, relative to patients who received polypharmacy for less than 30 days, those who received polypharmacy for 31-90, 91-180 and over 181 days had odds ratios of developing ARF of 1.33 (p<0.001), 1.65 (p<0.001) and 1.74 (p<0.001), respectively.

CONCLUSIONS

We observed statistically significant associations between the duration of polypharmacy and the occurrence of ARF.

Pre-injury polypharmacy as a predictor of outcomes in trauma patients

Background:

One of the hallmarks of modern medicine is the improving management of chronic health conditions. Long-term control of chronic disease entails increasing utilization of multiple medications and resultant polypharmacy. The goal of this study is to improve our understanding of the impact of polypharmacy on outcomes in trauma patients 45 years and older.

Materials and Methods:

Patients of age ≥45 years were identified from a Level I trauma center institutional registry. Detailed review of patient records included the following variables: Home medications, comorbid conditions, injury severity score (ISS), Glasgow coma scale (GCS), morbidity, mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, functional outcome measures (FOM), and discharge destination. Polypharmacy was defined by the number of medications: 0–4 (minor), 5–9 (major), or ≥10 (severe). Age- and ISS-adjusted analysis of variance and multivariate analyses were performed for these groups. Comorbidity–polypharmacy score (CPS) was defined as the number of pre-admission medications plus comorbidities. Statistical significance was set at alpha = 0.05.

Results:

A total of 323 patients were examined (mean age 62.3 years, 56.1% males, median ISS 9). Study patients were using an average of 4.74 pre-injury medications, with the number of medications per patient increasing from 3.39 for the 45–54 years age group to 5.68 for the 75+ year age group. Age- and ISS-adjusted mortality was similar in the three polypharmacy groups. In multivariate analysis only age and ISS were independently predictive of mortality. Increasing polypharmacy was associated with more comorbidities, lower arrival GCS, more complications, and lower FOM scores for self-feeding and expression-communication. In addition, hospital and ICU LOS were longer for patients with severe polypharmacy. Multivariate analysis shows age, female gender, total number of injuries, number of complications, and CPS are independently associated with discharge to a facility (all, P < 0.02).

Conclusion:

Over 40% of trauma patients 45 years and older were receiving 5 or more medications at the time of their injury. Although these patients do not appear to have higher mortality, they are at increased risk for complications, lower functional outcomes, and longer hospital and intensive care stays. CPS may be useful when quantifying the severity of associated comorbid conditions in the context of traumatic injury and warrants further investigation.

Patterns of use of perioperative angiotensin-converting enzyme inhibitors in coronary artery bypass graft surgery with cardiopulmonary bypass: effects on in-hospital morbidity and mortality

BACKGROUND

Despite proven benefit in ambulatory patients with ischemic heart disease, the pattern of use of angiotensin-converting enzyme inhibitors (ACEIs) in coronary artery bypass graft surgery has been erratic and controversial.

METHODS AND RESULTS

This is a prospective observational study of 4224 patients undergoing coronary artery bypass graft surgery. The cohort included 1838 patients receiving ACEI therapy before surgery and 2386 (56.5%) without ACEI exposure. Postoperatively, the pattern of ACEI use yielded 4 groups: continuation, 915 (21.7%); withdrawal, 923 (21.8%); addition, 343 (8.1%); and no ACEI, 2043 (48.4%). Continuous treatment with ACEI versus no ACEI was associated with substantive reductions of risk of nonfatal events (adjusted odds ratio for the composite outcome, 0.69; 95% confidence interval, 0.52-0.91; P=0.009) and a cardiovascular event (odds ratio, 0.64; 95% confidence interval, 0.46-0.88; P=0.006). Addition of ACEI de novo postoperatively compared with no ACEI therapy was also associated with a significant reduction of risk of composite outcome (odds ratio, 0.56; 95% confidence interval, 0.38-0.84; P=0.004) and a cardiovascular event (odds ratio, 0.63; 95% confidence interval, 0.40-0.97; P=0.04). On the other hand, continuous treatment of ACEI versus withdrawal of ACEI was associated with decreased risk of the composite outcome (odds ratio, 0.50; 95% confidence interval, 0.38-0.66; P<0.001), as well as a decrease in cardiac and renal events (P<0.001 and P=0.005, respectively). No differences in in-hospital mortality and cerebral events were noted.

CONCLUSIONS

Our study suggests that withdrawal of ACEI treatment after coronary artery bypass graft surgery is associated with nonfatal in-hospital ischemic events. Furthermore, continuation of ACEI or de novo ACEI therapy early after cardiac surgery is associated with improved in-hospital outcomes.

Prevalence of potentially preventable unplanned hospitalizations caused by therapeutic failures and adverse drug withdrawal events among older veterans

Background. Studies of drug-related hospitalizations have focused on adverse drug reactions, but few data are available on therapeutic failures (TFs) and adverse drug withdrawal events (ADWEs) leading to hospitalization among community-dwelling older adults. Thus, we sought to describe the prevalence of unplanned hospitalizations caused by TFs and ADWEs. In addition, we evaluated factors associated with these events in a nationally representative sample of older Veterans. Methods. This study included 678 randomly selected unplanned hospitalizations of older (age ≥ 65 years) Veterans between December 1, 2003, and November 9, 2006. The main outcomes were hospitalizations caused by a TF and/or an ADWE as determined by a pair of health professionals from review of medication charts and application of the Therapeutic Failure Questionnaire and/or Naranjo ADWE algorithm, respectively. Preventability (ie, medication error) of the admission was also assessed. Results. Thirty-four TFs and eight ADWEs involving 54 drugs were associated with 40 (5.9%) Veterans' hospitalizations; of these admissions, 90.0% (36/40) were rated as potentially preventable mostly due to medication nonadherence and suboptimal prescribing. The most common TFs that occurred were heart failure exacerbations (n = 8), coronary heart disease symptoms (n = 6), tachyarrhythmias (n = 3), and chronic obstructive pulmonary disease exacerbations (n = 3). Half (4/8) of the ADWEs that occurred were cardiovascular in nature. Multivariable logistic regression modeling indicated that black Veterans (adjusted odds ratio 2.92, 95% CI 1.25-6.80) were significantly more likely to experience a TF-related admission compared with white Veterans. Conclusions. TF-related unplanned hospitalizations occur more frequently than ADWE-related admissions among older Veterans. Almost all TFs and/or ADWEs are potentially preventable.

Medication discontinuity errors in the perioperative period

BACKGROUND

Inappropriate withdrawal or continuation of medication in the perioperative period is associated with an increased risk for adverse events. To reduce this risk, it is important that patients take their regular medication as prescribed. We evaluated this treatment objective by studying the frequency and reasons for errors related to medication discontinuity in the perioperative period.

METHODS

Patients scheduled for non-cardiac surgery were included in this cross-sectional study. Perioperative medication intake was assessed at the holding area of the operation theatre complex and on the ward during the first 24 h after surgery. Medication intake data were obtained from medical records and by questioning patients and compared with pre-operative instructions.

RESULTS

The study included 701 patients, of whom 485 (69%) used regular medication. Medication was incorrectly taken or discontinued before surgery in 27% of the patients. In 57% of these patients, the reason for incorrect intake was an unclear or a falsely understood instruction before surgery. Post-operative medication errors occurred in 26% of the patients.

CONCLUSION

Medication errors occur frequently in the perioperative period, even in the era of an electronic medication file. Errors in prescription, administration and intake of medication are not easily solved because no single health care professional is responsible for adequate intake of medication in surgical patients. The anaesthesiologist should take on a more prominent role in regulating perioperative medication intake in surgical patients.

Fast track colorectal surgery

A "fast track" colon surgery program is the global package of perioperative care encompassing preoperative, operative, and postoperative techniques, which in aggregate result in fewer complications, a reduction in cost, less postoperative pain, a reduction in the hospital length of stay, and quicker return to work and normal activities. Results of fast track programs have shown significant advantages; however, strong evidence is forthcoming. Implementation of a fast track program requires a significant commitment and a multidisciplinary approach. Fast track principles may also be applied to anorectal surgery with good results.

Correlates of postoperative pain and intravenous patient-controlled analgesia use in younger and older surgical patients

OBJECTIVE

Age-related patterns in postoperative pain are unclear with reports of no age differences and less pain with age. The objective of this study was to identify correlates of pain and intravenous patient-controlled analgesia (i.v. PCA) morphine use in younger and older patients.

DESIGN

24 hours after surgery, patients completed measures of pain intensity and pain qualities. Surgical factors, i.v. PCA morphine intake, anticholinergic load, polypharmacy, physical status, previous chronic and postoperative pain, and PCA experience were measured.

SETTING

Two academic general hospitals. PATIENTS. Two hundred forty-six general surgery patients ranging in age from 18 to 82 years old.

RESULTS

In older patients, higher pain scores were associated with female gender and previous experience of postoperative PCA. In younger patients, higher pain scores were associated with female gender, previous surgery without PCA, and greater morphine intake. Lower pain was associated with being male, and no previous surgical experience in older patients, and lower morphine intake in younger patients. Morphine intake was higher in patients who were younger, had better physical status, higher anticholinergic load, and experience with PCA. Among younger patients, increased morphine use also was associated with surgical procedure and duration. Higher pain scores were more strongly associated with morphine use among younger than older patients.

CONCLUSIONS

The correlates of postoperative pain and morphine use may differ with age, and the same factor may have different effects across age groups. Research is needed into the mechanisms of these age-specific profiles.

Nil by mouth: a misleading statement

Preoperative fasting is universally accepted as a beneficial practice to reduce the risk of pulmonary aspiration of gastric contents during the induction of general anaesthesia. What is less clear for many junior doctors and nurses is the administration of oral medication during the fasting period. This study aims to highlight the subjective understanding of the statement, 'nil by mouth' with regard to drug administration.

Clinical pharmacology in the geriatric patient

Geriatric patients are a subset of older people with multiple comorbidities that usually have significant functional implications. Geriatric patients have impaired homeostasis and wide inter-individual variability. Comprehensive geriatric assessment captures the complexity of the problems that characterize frail older patients and can be used to guide management, including prescribing. Prescribing for geriatric patients requires an understanding of the efficacy of the medication in frail older people, assessment of the risk of adverse drug events, discussion of the harm:benefit ratio with the patient, a decision about the dose regime and careful monitoring of the patient's response. This requires evaluation of evidence from clinical trials, application of the evidence to frail older people through an understanding of changes in pharmacokinetics and pharmacodynamics, and attention to medication management issues. Given that most disease occurs in older people, and that older people are the major recipients of drug therapy in the Western world, increased research and a better evidence base is essential to guide clinicians who manage geriatric patients.

["Fast track" colorectal surgery]

Many factors have effect on the enhanced recovery after colon surgery. Not only the technical skill but the perioperative events needed to be optimized by the pre- and postoperative issues. Articles were obtained with search for keywords in Medline electronic database and evidences have been ranked according to the recommendation of the Oxford Evidence-Based Medicine Centre. Multicentric, randomised studies have proved that preoperative bowel emptying could not decrease the number of anastomotic insufficiency and wound infection rate; the use of abdominal drains is not necessary in every case; the proper, early oral intake is safe and well tolerated in colo-rectal surgery, and with laparoscopic surgery the same results can be achieved as with open ones. The evidences found even are not used completely. The advantage of laparoscopic surgery can be improved with fast track methods. To use correctly the affecting factors it is essential to know the current literature.

Does coronary artery bypass surgery affect metoprolol bioavailability

BACKGROUND

beta-blockers are commonly administered in patients with coronary artery bypass surgery (CABG). Despite this therapy, however, the incidence of postoperative atrial fibrillation (AF) is high (9-19%), and it is unknown why the beta-blockers do not reduce the incidence of AF more efficiently. In this pharmacokinetics study, in which the patients acted as their own controls, we have evaluated the bioavailability of perioperative metoprolol tablets in CABG surgery patients.

METHODS

Twelve male patients, aged 45-64 years, scheduled for CABG surgery were administered an initial 50 mg metoprolol tartrate tablet orally on the morning of the preoperative day and thereafter at 12-h intervals. Regular blood samples were collected up to 12 h after the first administration of the drug on the preoperative day as well on the first and third postoperative days. The plasma concentration for metoprolol was analyzed (limit of quantification = 0.001 mg/L) using liquid chromatography-tandem mass spectrometry.

RESULTS

The bioavailability of the metoprolol was significantly less on the first postoperative day, with AUC(0-12) values ranging from 0.7 to 17.1 (median: 7.2) mg min/L, than on the preoperative day, with AUC(0-12) values of 5.1-26.7 (12.6) mg min/L; however, it returned to the preoperative values on the third postoperative day, with AUC(0-12) values of 3.5-25.2 (15.2) mg min/L. Similar changes were observed in C(max) values: preoperative C(max) ranged between 0.026 and 0.123 (0.060) mg/L, on the first postoperative day, the C(max) ranged between 0.003 and 0.093 (0.025) mg/L, and on the third postoperative day, the C(max) ranged between 0.009 and 0.136 (0.061) mg/L. There was no correlation between the pharmacokinetic parameters and patient characteristics, but both the preoperative C(max) and C(60) correlated significantly with the postoperative C(max) (Pearson correlation coefficient: 0.61-0.72). One patient with one of the lowest rates and extent of metoprolol absorption developed AF.

CONCLUSION

This study indicates that the bioavailability of metoprolol is markedly reduced when administered in tablet form during the early phase after CABG.

An observational study of changes to long-term medication after admission to an intensive care unit

Many patients admitted to intensive care units consume long-term medication. New drugs may be commenced during intensive care intended for the short term or longer. Patients are often cared for by several teams during hospital admission and long-term medication may inadvertently be permanently discontinued. Following admission, new therapies relevant only in the short term could be continued beyond intensive care and hospital discharge. We conducted a retrospective analysis of drug prescription by examining patients' notes and charts before, during and after intensive care admission. Of 197 drugs prescribed up to intensive care admission to 59 patients, 112 (57%) were stopped. Ninety-nine of these were not reintroduced by intensive care discharge and 34 were not reintroduced by hospital discharge. Of 154 drugs commenced during intensive care, 96 (62%) had no listed reason for their introduction. Twenty-eight were continued beyond hospital discharge, some without apparent ongoing indication. Reliable mechanisms to prevent prescription errors are required.

Interférence des médicaments cardiovasculaires avec l'anesthésie et la chirurgie

Decisions about chronic treatments during the perioperative period must be made at the presurgical anesthesia consultation. It is increasingly rare to stop treatment during this period, because: This new rule is applied particularly to patients with cardiovascular disorders. Beta blockers have a special role in preventing the onset of postoperative cardiovascular events. The role of statins requires further precision but they appear to fit into the same preventive approach. Interruption of antiplatelet agents appears to be associated with a risk of arterial thrombosis in patients with coronary conditions, notably those with conventional stents and most especially those with drug-eluting stents.

Preoperative cardiac drug administration in general surgical patients: A completed audit

The aim of this study was to audit the preoperative administration of regular cardiac medication in general surgical patients and to determine if this can be improved with simple ward-based education. The notes and drug charts of 102 general surgical adult inpatients undergoing elective operations were analysed prospectively. It was noted whether the patient was on regular morning cardiac medication, whether this was given and, if not, whether a reason was recorded on the drug chart. An information sheet and brief verbal reinforcement was given to nursing staff and junior doctors and the review repeated in 111 patients. There was no significant difference in the number of patients on regular cardiac medication between the two review groups; 42% patients had one or more drugs omitted in the initial review. After education this reduced significantly to 20% (p = 0.023). When omissions on medical instruction were excluded, this became highly significant (p = 0.0029). There was also a significant decrease in the number of times 'nil by mouth' was stated as the reason for omission. As a general principle, all regular cardiac medication should be given preoperatively even when nil by mouth as there is evidence that abrupt withdrawal can have serious consequences. This audit demonstrates that with simple education, the proportion of regular cardiac drugs administered preoperatively can be significantly increased.

Drug absorption from the small intestine in immediate postoperative patients

BACKGROUND

The effects of surgery on gastric emptying have been documented for a considerable time, but less is known about the effects in the small intestine. It is thought that there is minimal diminution in the absorptive capacity of the small intestine after operation, although there is no literature on drug absorption in the early period after surgery. This study investigated drug absorption from the small bowel in patients undergoing abdominal surgery.

METHODS

A prospective study of patients undergoing major abdominal surgery in which patients acted as their own preoperative controls was carried out. Patients were administered the test substances, acetaminophen and (99m)TcDTPA, before operation and 2 days after operation. Small intestine transit times, plasma concentrations and other pharmacokinetic variables were compared using Student's paired t-test. Two complementary studies were carried out to establish pharmacokinetic parameters.

RESULTS

There were no significant differences in the pre- and postoperative values of t(max), area under the curve, and area under the moment curve (AUMC) before and after operation (P>0.05). There were significant differences between the pre- and postoperative values of C(max) [C(max (preop))>C(max (postop)); P<0.05] and the pre- and postoperative values of mean residence time (MRT) [MRT((preop))<MRT((postop)); P<0.01].

CONCLUSIONS

Drug absorption from the small bowel in the postoperative patient does not differ significantly from its preoperative absorptive capacity.

Präoperative Dauertherapie

A large number of patients undergoing elective surgical procedures already take routine medication preoperatively. The majority of these patients use drugs for therapy of preexisting cardiovascular, pulmonary or endocrinological diseases which are independent of the planned surgical procedure. The number and type of preoperative drug therapy are correlated to age, gender and co-morbidity of the patients. Furthermore, patients with higher ASA-classes usually take more drugs, as they suffer from several medical diseases. Information about the perioperative handling of routine drug therapy is important for the planning of anaesthesia and surgery. A close cooperation of all medical specialities involved is necessary, in particular when patients take anticoagulants or other substances which should be withdrawn or replaced. This review focuses on the handling of routine preoperative medication by the anaesthesiologist in the light of available literature.

Medication use in the elderly patient: focus on the perioperative/perianesthesia setting

As the population ages, the use of multiple medications also increases. Polypharmacy (taking multiple drugs at a time) presents concerns to the perianesthesia nurse who is caring for the geriatric patient. The pharmacokinetics and pharmacodynamics of drugs are often altered in older adult patients. Adverse drug reactions and drug interactions occur more often in geriatric patients than in younger patients. For these reasons, the benefits and risks of multiple medications and the administration of certain types of drugs must be carefully considered in the elderly patient. The selection of any medication should be individually based on the benefits and risks. Adverse drug reactions play a significant role in hospitalization for the general population, and the elderly are more susceptible to these. These drug reactions often contribute to significant morbidity as well as mortality. Medications need to be considered carefully in the older adult patient, but perhaps more so in the perioperative/perianesthesia period. Drug interactions are diverse. The type of anesthesia may influence the patient's outcome, depending on the medications the patient is currently taking. The patient's response to the stress of surgery is also affected by individual medical conditions as well as medications the patient is currently receiving Polypharmacy, inappropriate medications, adverse drug reactions, drug-disease issues, and drug interactions in the geriatric population are concerns in the perioperative/perianesthesia setting.

The prevalence and predictors of herbal medicine use in surgical patients

BACKGROUND

Despite the rapid rise in herbal medicine consumption, explicitly eliciting and documenting herbal medicine usage among surgical patients is poor.

STUDY DESIGN

A survey by means of a self-administered questionnaire was conducted among patients undergoing elective surgery inquiring into the self-health perceptions, herbal medicine use, and communication of such usage to surgical health-care staff.

RESULTS

Sixty-five percent (n =2,186) of all the patients undergoing elective surgery completed the survey during a 10-week period. Fifty-seven percent of respondents admitted to using herbal medicine at some point in their life, 38% in the past 2 years (eg, echinacea [48%], aloe vera [30%], ginseng [28%], garlic [27%], and ginkgo biloba [22%] were the most common). One in six respondents continued the use of herbal medicine during the month of surgery. Herbal medicine usage was significantly higher among patients undergoing a gynecologic procedure (odds ratio [OR] 1.68; 95% confidence interval [CI] 1.29 to 2.18) and patients with a self-perception of good health (OR 1.32; 95% CI 1.04 to 1.69); it was lower among patients with a history of pulmonary symptoms (OR 0.77; 95% CI 0.62 to 0.94), African Americans (OR 0.69; 95% CI 0.51 to 0.95), in patients having a primary care physician (OR 0.71; 95% CI 0.52 to 0.98), in patients with a history of diabetes mellitus (OR 0.46; 95% CI 0.32 to 0.68), and in patients undergoing vascular surgery (OR 0.19; 95% CI 0.07 to 0.48).

CONCLUSIONS

Herbal medicine use is common among surgical patients and is consistent with the substantial increase in the use of alternative medical therapies. Awareness of this rising herbal medicine usage and documentation of the use of herbal medicines by surgical health-care staff is important to prevent, recognize, and treat potential problems that may arise from herbal medications taken alone or in conjunction with conventional medications during the perioperative period.

[Drug interactions and the anesthesiologist]

Eines der Grundprinzipien der modernen Anästhesie ist die Kombination unterschiedlicher Pharmaka aus verschiedenen Substanzgruppen. Zusätzlich sehen sich Anästhesisten häufig mit der umfangreichen medikamentösen Dauertherapie chronisch kranker Patienten konfrontiert. Werden zwei oder mehrere Medikamente gleichzeitig appliziert, kann sich der pharmakologische Effekt von der Summe der einzeln verabreichten Substanzen unterscheiden. Das kann erwünscht, aber für den Patienten auch potenziell gefährlich sein. Die Wahrscheinlichkeit einer unerwünschten Arzneimittelwechselwirkung steigt exponentiell mit der Anzahl der verabreichten Medikamente und kann sowohl auf pharmazeutischer, pharmakodynamischer wie pharmakokinetischer Ebene entstehen. Obwohl die Fülle der Interaktionsmöglichkeiten enorm und die Komplexität der Arzneimittelwechselwirkungen schwer greifbar und zu identifizieren sind, gelten ernsthafte Medikamenteninteraktionen in der Anästhesie allgemein als vorhersehbar. Neben der Erkennung der Risikofaktoren wie Leber- und Niereninsuffizienz, ASA-Status sowie metabolische und endokrine Veränderungen des Patienten sind grundlegende Kenntnisse und ein Verständnis der allgemeinen und speziellen Pharmakologie notwendig, um unerwünschte Arzneimittelwechselwirkungen zu verhindern.

Co-medications, pre-medication and common diseases in the elderly

Typically, old patients scheduled to undergo a surgical procedure take many medications for various disorders. The anaesthetist must consider the benefits and/or risks of continuation or withdrawal of such chronic medications. This chapter reviews these issues in respect of cardiovascular drugs (calcium channel blockers, beta adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists) and of psychotropic and antiparkinson medications and insulin. Focus is put on the few scientific studies available and on the recommendations given by experts in the field.

Interrupting drug therapy in the perioperative period

Millions of patients undergo surgery each year and an increasing proportion of these patients are consuming therapeutic drugs. Drug therapy is often withheld in the immediate perioperative period and after major surgery, in particular, there is often a prolonged period of fasting. This may lead to withdrawal effects including recurrence or worsening of patients' disease symptomatology. These effects will occur during a period of physiological and pathophysiological stresses and render patients more vulnerable to drug withdrawal phenomena. Thus, patients may be exposed to greater and sometimes unnecessary risks in the perioperative period. There are relatively few studies that have investigated this problem. The ones that have, however, confirm that drug abstinence in the perioperative period is a relatively common phenomenon and one study has demonstrated an association between duration of drug abstinence and adverse outcomes. The pathophysiological effects of major surgery on gastrointestinal function, neuro-humoral and cytokine adaptive responses to surgical stress are under-appreciated. These responses can reduce the effectiveness of oral administration and exacerbate co-existing disease processes. These problems are compounded by a fragmented approach to perioperative drug therapy with no one group of healthcare professionals assuming responsibility for this aspect of care. This may in part be a consequence of the complexities of rationalising drug therapy in the perioperative period together with the lack of readily available and evidence based information strategies for individual drugs or drug classes. An additional problem relates to the formulations, inherent pharmacokinetics and limited routes of administration of many prescribed drugs. These can prevent a 'seamless' transition from preoperative to postoperative management. Consumers, health professionals, pharmaceutical companies and drug regulatory agencies must all play a part in rectifying this problem. There remains a need for further research to clarify the effects of abstinence on patient outcomes and also to identify optimum strategies to avoid unwanted drug abstinence.

Drug interactions

The prevalence of undesirable drug interactions is substantial but largely unknown. Although drug interactions are certainly an important cause of drug toxicity, their clinical significance may have been exaggerated. This review presents a brief overview of possible drug interactions.