Considerations for general anaesthesia in Parkinson's disease

Parkinson's disease is a common neurodegenerative disorder in the elderly which when present has a significant influence on surgical management. These patients necessitate additional perioperative and anaesthetic considerations across disease specific domains as well as in relation to the respiratory and cardiovascular systems. This brief review focuses on the factors which contribute to perioperative morbidity, including the use of medications that may exacerbate symptoms or adversely interact with treatments for Parkinson's disease. Recommended dosing practices to reduce complications during hospitalisation are covered. In addition, recent concerns regarding anaesthetic exposure in early childhood as a risk factor for the development of Parkinson's disease are discussed in light of data from animal models of anaesthetic neurotoxicity and epidemiological studies.

Safety of perioperative treatment with intravenous amantadine in patients with Parkinson disease

OBJECTIVES

Surgery in patients with Parkinson disease is associated with a high rate of complications largely because of difficulties in maintaining the antiparkinsonian treatment regimen perioperatively. The aim of the study was to investigate the safety and efficacy of intravenous administration of amantadine on parkinsonian features during and after surgery.

METHODS

The study group included 6 patients being treated for Parkinson disease who were referred for surgery at a tertiary medical center. After providing written informed consent, participants received intravenous amantadine sulfate 200 mg after induction of anesthesia and 24 hours later. The regular antiparkinsonian regimen was stopped immediately before surgery and restarted after surgery. Patients underwent a neurological evaluation with the Unified Parkinson Disease Rating Scale at 3 time points: preoperatively, 24 to 72 hours postoperatively, and 1 month postoperatively, and the scores were compared.

RESULTS

The mean Unified Parkinson Disease Rating Scale score improved from 24.8 (SD, 10.8) at baseline to 21.3 (SD, 11.1) at 24 to 72 hours postoperatively (P = 0.04); the value at 1 month (in the 5 patients assessed) was 22.5 (SD, 15.5) (P = 0.27). No adverse effects of amantadine or postoperative complications were recorded. All patients were discharged home as planned.

CONCLUSIONS

Amantadine improves the parkinsonian symptoms after surgery, which may be beneficial in preventing complications. It appears to have a high safety profile in this setting. Larger, randomized, and blinded studies are warranted to corroborate these preliminary results and evaluate long-term outcome.

Therapeutic concerns when oral medications are administered nasogastrically

WHAT IS KNOWN AND OBJECTIVE

Administering oral medications to patients with nasogastric tube (NGT) is a challenging patient-care issue. Inappropriate prescribing behaviour and incorrect procedure for extemporaneous preparation of oral suspensions given via NGT may result in significant harm to patients. There are many drugs which have not been tested regarding oral absorption profile and bioavailability derived from NGT dosing. Although several studies and case-reports have been reported, there is no up-to-date review of drug administration via NGT. The aim of this review is to increase awareness of rational drug administration via NGT and to encourage relevant research in this area.

METHODS

Full prescribing information from each currently available oral medication was reviewed for any data indicating that the medication could not be crushed or opened. Literature was identified by searching PubMed (1988 to Aug 2012).

RESULTS AND DISCUSSION

There is evidence to show that NGT dosing of some medications may bring both benefits (e.g. cost saving) and disadvantages (e.g. decrease in efficacy and/or safety). For medications with package inserts that warn that they should not be crushed or opened, alternatives are usually recommended. However, in some cases, there is evidence to support NGT dosing. Sometimes special procedures are required to avoid problems such as instability, interaction with enteral nutrition, adsorption, tube obstruction and low recovery when preparing extemporaneous oral suspensions.

WHAT IS NEW AND CONCLUSION

Physicians, pharmacists and nurses should know the procedures for drug administration by NGT, as well as the latest evidence on such administrations. There may not be bioequivalence between oral and nasogastric administrations. Care must be taken to avoid compromising the physicochemical, biopharmaceutical and pharmacological properties of drugs given by NGT to ensure their safety and efficacy.

Appropriateness of administration of nasogastric medication and preliminary intervention

A utilization study was performed in a 2200-bed tertiary care teaching hospital. Data mining was performed on all nasogastric medication prescriptions for patients hospitalized in 2011. Nurses were interviewed by questionnaire. A PDCA (Plan-Do-Check-Act) cycle was used for continuous quality improvement. The proportion of patients with nasogastric tubes (NGT) was 3.2%. A large number of medical orders (n = 6261) involved nasogastric medications with a package insert particularly noting that they should not be crushed or opened (group 1) or medications without a specific formulation recommendation in the package insert but having evidence discouraging NGT dosing (group 2). Of the nasogastrically administered sustained-release or controlled-release formulations, a sustained-release sodium valproate tablet formulation was the most prescribed drug and a sustained-release 2.5 mg felodipine tablet was prescribed with the highest proportion of NGT dosing [NGT/(NGT + oral) = 12.3%]. Among the nasogastrically administered enteric-coated formulations, a myrtol-standardized enteric-coated capsule formulation was the most prescribed drug and a pantoprazole tablet formulation was prescribed with the highest proportion of NGT dosing [NGT/(NGT + oral) = 19.3%]. Proportions of NGT dosing for amiodarone and carbamazepine (group 2) were 4.8% and 6.3%, respectively. The percentage of nurses with adequate knowledge about pharmaceutical dosage formulations was 60%. The rate of answering correctly as to whether medications in group 1 could be crushed or opened was only 30%. Awareness of evidence discouraging NGT dosing of medications in group 2 was zero. Most nurses (90%) left physicians and pharmacists with the entire responsibility for knowledge and decision-making concerning route of drug administration. After a 3-month preliminary intervention, irrational medical orders involving nasogastric administration of medications in group 1 were successfully abolished. The rate of answering correctly as to whether medications in group 1 could be crushed or opened increased to 100%. This utilization study indicates poor awareness concerning nasogastric administration of medication on the part of physicians and nurses, and preliminary intervention measures were efficient in improving knowledge through team cooperation and effort.