Increased CSF levels of aromatic amino acids in hip fracture patients with delirium suggests higher monoaminergic activity

BACKGROUND

To examine whether delirium in hip fracture patients was associated with changes in the levels of amino acids and/or monoamine metabolites in cerebrospinal fluid (CSF) and serum.

METHODS

In this prospective cohort study, 77 patients admitted with an acute hip fracture to Oslo University Hospital, Norway, were studied. The concentrations of amino acids in CSF and serum were determined by high performance liquid chromatography. The patients were assessed daily for delirium by the Confusion Assessment Method (pre-operatively and post-operative day 1-5 (all) or until discharge (delirious patients)). Pre-fracture dementia status was decided by an expert panel. Serum was collected pre-operatively and CSF immediately before spinal anesthesia.

RESULTS

Fifty-three (71 %) hip fracture patients developed delirium. In hip fracture patients without dementia (n = 39), those with delirium had significantly higher CSF levels of tryptophan (40 % higher), tyrosine (60 % higher), phenylalanine (59 % higher) and the monoamine metabolite 5-hydroxyindoleacetate (23 % higher) compared to those without delirium. The same amino acids were also higher in CSF in delirious patients with dementia (n = 38). The correlations between serum and CSF amino acid levels were poor.

CONCLUSION

Higher CSF levels of monoamine precursors in hip fracture patients with delirium suggest a higher monoaminergic activity in the central nervous system during delirium in this patient group.

Active perioperative patient warming using a self-warming blanket (BARRIER EasyWarm) is superior to passive thermal insulation: a multinational, multicenter, randomized trial

STUDY OBJECTIVE

Incidence of inadvertent perioperative hypothermia is still high; therefore, present guidelines advocate "prewarming" for its prevention. Prewarming means preoperative patient skin warming, which minimizes redistribution hypothermia caused by induction of anesthesia. In this study, we compared the new self-warming BARRIER EasyWarm blanket with passive thermal insulation regarding mean perioperative patient core body temperature.

DESIGN

Multinational, multicenter randomized prospective open-label controlled trial.

SETTING

Surgical ward, operation room, postanesthesia care unit at 4 European hospitals.

PATIENTS

A total of 246 adult patients, American Society of Anesthesiologists class I to III undergoing elective orthopedic; gynecologic; or ear, nose, and throat surgery scheduled for 30 to 120 minutes under general anesthesia.

INTERVENTIONS

Patients received warmed hospital cotton blankets (passive thermal insulation, control group) or BARRIER EasyWarm blanket at least 30 minutes before induction of general anesthesia and throughout the perioperative period (intervention group).

MEASUREMENTS

The primary efficacy outcome was the perioperative mean core body temperature measured by a tympanic infrared thermometer. Secondary outcomes were hypothermia incidence, change in core body temperature, length of stay in postanesthesia care unit, thermal comfort, patient satisfaction, ease of use, and adverse events related to the BARRIER EasyWarm blanket.

MAIN RESULTS

The BARRIER EasyWarm blanket significantly improved perioperative core body temperature compared with standard hospital blankets (36.5°C, SD 0.4°C, vs 36.3, SD 0.3°C; P<.001). Intraoperatively, in the intervention group, hypothermia incidence was 38% compared with 60% in the control group (P=.001). Postoperatively, the figures were 24% vs 49%, respectively (P=.001). Patients in the intervention group had significantly higher thermal comfort scores, preoperatively and postoperatively. No serious adverse effects were observed in either group.

CONCLUSIONS

Perioperative use of the new self-warming blanket improves mean perioperative core body temperature, reduces the incidence of inadvertent perioperative hypothermia, and improves patients' thermal comfort during elective adult surgery.

Cerebrospinal fluid levels of neopterin are elevated in delirium after hip fracture

BACKGROUND

The inflammatory cell product neopterin is elevated in serum before and during delirium. This suggests a role for disordered cell-mediated immunity or oxidative stress. Cerebrospinal fluid (CSF) neopterin levels reflect brain neopterin levels more closely than serum levels. Here we hypothesized that CSF neopterin levels would be higher in delirium.

METHODS

In this prospective cohort study, 139 elderly patients with acute hip fracture were recruited in Oslo and Edinburgh. Delirium was diagnosed with the confusion assessment method performed daily pre-operatively and on the first 5 days post-operatively. Paired CSF and blood samples were collected at the onset of spinal anaesthesia. Neopterin levels were measured using high-performance liquid chromatography.

RESULTS

Sixty-four (46 %) of 139 hip fracture patients developed delirium perioperatively. CSF neopterin levels were higher in delirium compared to controls (median 29.6 vs 24.7 nmol/mL, p = 0.003), with highest levels in patients who developed delirium post-operatively. Serum neopterin levels were also higher in delirium (median 37.0 vs 27.1 nmol/mL, p = 0.003). CSF neopterin remained significantly associated with delirium after controlling for relevant risk factors. Higher neopterin levels were associated with poorer outcomes (death or new institutionalization) 1 year after surgery (p = 0.02 for CSF and p = 0.03 for serum).

CONCLUSIONS

This study is the first to examine neopterin in CSF from patients with delirium. Our findings suggest potential roles for activation of cell-mediated immune responses or oxidative stress in the delirium process. High levels of serum or CSF neopterin in hip fracture patients may also be useful in predicting poor outcomes.

Alterations in the coupling functions between cortical and cardio-respiratory oscillations due to anaesthesia with propofol and sevoflurane

The precise mechanisms underlying general anaesthesia pose important and still open questions. To address them, we have studied anaesthesia induced by the widely used (intravenous) propofol and (inhalational) sevoflurane anaesthetics, computing cross-frequency coupling functions between neuronal, cardiac and respiratory oscillations in order to determine their mutual interactions. The phase domain coupling function reveals the form of the function defining the mechanism of an interaction, as well as its coupling strength. Using a method based on dynamical Bayesian inference, we have thus identified and analysed the coupling functions for six relationships. By quantitative assessment of the forms and strengths of the couplings, we have revealed how these relationships are altered by anaesthesia, also showing that some of them are differently affected by propofol and sevoflurane. These findings, together with the novel coupling function analysis, offer a new direction in the assessment of general anaesthesia and neurophysiological interactions, in general.

Gradual withdrawal of remifentanil infusion may prevent opioid-induced hyperalgesia

BACKGROUND

The aim of this study was to examine if gradual withdrawal of remifentanil infusion prevented opioid-induced hyperalgesia (OIH) as opposed to abrupt withdrawal. OIH duration was also evaluated.

METHODS

Nineteen volunteers were enrolled in this randomized, double-blinded, placebo-controlled, crossover study. All went through three sessions: abrupt or gradual withdrawal of remifentanil infusion and placebo. Remifentanil was administered at 2.5 ng ml(-1) for 30 min before abrupt withdrawal or gradual withdrawal by 0.6 ng ml(-1) every five min. Pain was assessed at baseline, during infusion, 45-50 min and 105-110 min after end of infusions using the heat pain test (HPT) and the cold pressor test (CPT).

RESULTS

The HPT 45 min after infusion indicated OIH development in the abrupt withdrawal session with higher pain scores compared with the gradual withdrawal and placebo sessions (both P<0.01. Marginal mean scores: placebo 2.90; abrupt 3.39; gradual 2.88), but no OIH after gradual withdrawal compared with placebo (P=0.93). In the CPT 50 min after end of infusion there was OIH in both remifentanil sessions compared with placebo (gradual P=0.01, abrupt P<0.01. Marginal mean scores: placebo 4.56; abrupt 5.25; gradual 5.04). There were no differences between the three sessions 105-110 min after infusion.

CONCLUSIONS

We found no development of OIH after gradual withdrawal of remifentanil infusion in the HPT. After abrupt withdrawal OIH was present in the HPT. In the CPT there was OIH after both gradual and abrupt withdrawal of infusion. The duration of OIH was less than 105 min for both pain modalities.

CLINICAL TRIAL REGISTRATION

NCT 01702389. EudraCT number 2011-002734-39.

The discriminatory value of cardiorespiratory interactions in distinguishing awake from anaesthetised states: a randomised observational study

Depth of anaesthesia monitors usually analyse cerebral function with or without other physiological signals; non‐invasive monitoring of the measured cardiorespiratory signals alone would offer a simple, practical alternative. We aimed to investigate whether such signals, analysed with novel, non‐linear dynamic methods, would distinguish between the awake and anaesthetised states. We recorded ECG, respiration, skin temperature, pulse and skin conductivity before and during general anaesthesia in 27 subjects in good cardiovascular health, randomly allocated to receive propofol or sevoflurane. Mean values, variability and dynamic interactions were determined. Respiratory rate (p = 0.0002), skin conductivity (p = 0.03) and skin temperature (p = 0.00006) changed with sevoflurane, and skin temperature (p = 0.0005) with propofol. Pulse transit time increased by 17% with sevoflurane (p = 0.02) and 11% with propofol (p = 0.007). Sevoflurane reduced the wavelet energy of heart (p = 0.0004) and respiratory (p = 0.02) rate variability at all frequencies, whereas propofol decreased only the heart rate variability below 0.021 Hz (p < 0.05). The phase coherence was reduced by both agents at frequencies below 0.145 Hz (p < 0.05), whereas the cardiorespiratory synchronisation time was increased (p < 0.05). A classification analysis based on an optimal set of discriminatory parameters distinguished with 95% success between the awake and anaesthetised states. We suggest that these results can contribute to the design of new monitors of anaesthetic depth based on cardiovascular signals alone.

The effect of a pre- and postoperative orthogeriatric service on cognitive function in patients with hip fracture: randomized controlled trial (Oslo Orthogeriatric Trial)

BACKGROUND

Delirium is a common complication in patients with hip fractures and is associated with an increased risk of subsequent dementia. The aim of this trial was to evaluate the effect of a pre- and postoperative orthogeriatric service on the prevention of delirium and longer-term cognitive decline.

METHODS

This was a single-center, prospective, randomized controlled trial in which patients with hip fracture were randomized to treatment in an acute geriatric ward or standard orthopedic ward. Inclusion and randomization took place in the Emergency Department at Oslo University hospital. The key intervention in the acute geriatric ward was Comprehensive Geriatric Assessment including daily interdisciplinary meetings. Primary outcome was cognitive function four months after surgery measured using a composite outcome incorporating the Clinical Dementia Rating Scale (CDR) and the 10 words learning and recalls tasks from the Consortium to Establish a Registry for Alzheimer's Disease battery (CERAD). Secondary outcomes were pre- and postoperative delirium, delirium severity and duration, mortality and mobility (measured by the Short Physical Performance Battery (SPPB)). Patients were assessed four and twelve months after surgery by evaluators blind to allocation.

RESULTS

A total of 329 patients were included. There was no significant difference in cognitive function four months after surgery between patients treated in the acute geriatric and the orthopedic wards (mean 54.7 versus 52.9, 95% confidence interval for the difference -5.9 to 9.5; P = 0.65). There was also no significant difference in delirium rates (49% versus 53%, P = 0.51) or four month mortality (17% versus 15%, P = 0.50) between the intervention and the control group. In a pre-planned sub-group analysis, participants living in their own home at baseline who were randomized to orthogeriatric care had better mobility four months after surgery compared with patients randomized to the orthopedic ward, measured with SPPB (median 6 versus 4, 95% confidence interval for the median difference 0 to 2; P = 0.04).

CONCLUSIONS

Pre- and postoperative orthogeriatric care given in an acute geriatric ward was not effective in reducing delirium or long-term cognitive impairment in patients with hip fracture. The intervention had, however, a positive effect on mobility in patients not admitted from nursing homes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01009268 Registered November 5, 2009.

Plasmoid formation in current sheet with finite normal magnetic component

Current sheet configurations in natural and laboratory plasmas are often accompanied by a finite normal magnetic component that is known to stabilize the two-dimensional resistive tearing instability in the high Lundquist number regime. Recent magnetohydrodynamic simulations indicate that the nonlinear development of ballooning instability is able to induce the formation of X lines and plasmoids in a generalized Harris sheet with a finite normal magnetic component in the high Lundquist number regime where the linear two-dimensional resistive tearing mode is stable.

Perioperative care for the older outpatient undergoing ambulatory surgery

As the number of ambulatory surgery procedures continues to grow in an aging global society, the implementation of evidence-based perioperative care programs for the elderly will assume increased importance. Given the recent advances in anesthesia, surgery, and monitoring technology, the ambulatory setting offers potential advantages for elderly patients undergoing elective surgery. In this review article we summarize the physiologic and pharmacologic effects of aging and their influence on anesthetic drugs, the important considerations in the preoperative evaluation of elderly outpatients with coexisting diseases, the advantages and disadvantages of different anesthetic techniques on a procedural-specific basis, and offer recommendations regarding the management of common postoperative side effects (including delirium and cognitive dysfunction, fatigue, dizziness, pain, and gastrointestinal dysfunction) after ambulatory surgery. We conclude with a discussion of future challenges related to the growth of ambulatory surgery practice in this segment of our surgical population. When information specifically for the elderly population was not available in the peer-reviewed literature, we drew from relevant information in other ambulatory surgery populations.

Effect of a single dose of pregabalin on post-operative pain and pre-operative anxiety in patients undergoing discectomy

BACKGROUND

Pregabalin acts as a membrane stabilizer and has both analgesic and anxiolytic effects. We hypothesized that one pre-operative dose of pregabalin would reduce pre-operative anxiety and post-operative pain in patients undergoing discectomy.

METHODS

We performed a randomized, placebo-controlled study of 150 mg pregabalin administered before lumbar discectomy in general anaesthesia. The primary endpoint was pain at rest [visual analogue scale (VAS)] 120 min after surgery. The secondary outcomes were morphine consumption, pre-operative anxiety (VAS) and the occurrence of side effects.

RESULTS

The VAS scores for pain at rest and morphine consumption were higher in the placebo group during the 4-h stay in the post-anaesthetic care unit (PACU), but did not differ significantly 24 h after surgery. Pain scores at 7 days were similar and there was no difference in the occurrence of side effects. Pre-operative anxiety was significantly lower in the pregabalin group (2.23±1.11 vs. 4.17±2.37, 95% confidence interval: 0.82-3.05, P=0.001) and there was a significant positive correlation between the pre-operative anxiety score and post-operative pain at 120 min in the pregabalin group.

CONCLUSIONS

A single dose of pregabalin (150 mg) reduced post-operative pain at rest and morphine consumption during the PACU period after lumbar discectomy. Pre-operative anxiety was lower, without increased incidence of side effects.

[Ambulatory surgery and anaesthesia]

BACKGROUND

Most surgical procedures in Norway are performed on an ambulatory basis. Many types of health professionals are involved and need training in how to handle these patients. The paper reviews important aspects of handling ambulatory surgical patients.

MATERIAL AND METHODS

The authors' research, clinical experience from ambulatory anaesthesiology and literature identified through a non-systematic search in Medline and EMBASE form the basis for the article.

RESULTS

With the advent of modern techniques, anaesthesia is no longer a limiting factor for whether surgery can be performed on an ambulatory basis or not. The decision to hospitalize a patient after elective surgery is based on limitations in the patient's general health, daily functioning and psychosocial status or the type of surgical procedure planned. When assessing whether surgery can be elective or not it is valuable to consider the entire treatment chain and ask the following questions: Can this patient who has undergone this procedure be expected to cope with transport and staying at home or in a hotel the same day as the operation, when escorted by an adult until the next day? - and is it safe?

INTERPRETATION

To ensure good planning and performance, it is important that the anaesthetist has access to up-to-date information on planned surgical procedures, the patient's general health, use of medication, allergies and level of daily functioning.

[Choice of anaesthetic approach and anaesthetic drugs]

BACKGROUND

All types of anaesthesia should ensure absence of pain, inhibit autonomic responses and provide optimal conditions for surgery. Choice of anaesthetic approach (local, regional or general anaesthesia or a combination of methods) depends on type of surgery and the patients' health and preferences.

MATERIAL AND METHODS

The review is based on literature identified through non-systematic searches in PubMed and own research and experience.

RESULTS

When selecting anaesthetic approach and anaesthetic drugs one has to consider not only the perioperative period, but also postoperative aspects such as pain relief, awakeness, functional ability and absence of nausea. After major surgery, regional anaesthesia (especially epidural anaesthesia) and postoperative analgesia have been shown to reduce pulmonary complications and chronic pain. General anaesthesia can be administered either by volatile agents for inhalation, intravenous hypnotics, potent opioids or a combination (often used). Volatile agents, shown to be cardioprotective during cardiac surgery, are recommended for major non-cardiac surgery in patients with heart disease (even though clinical documentation is limited).

INTERPRETATION

An appropriate anaesthetic approach, taking into account patient characteristics and type of surgery, is important for safety and potential complications. In some situations, the anaesthetic approach and anaesthetic drugs may have an impact on outcome.

Brief report: improved pain relief using intermittent bupivacaine injections at the donor site after breast reconstruction with deep inferior epigastric perforator flap

BACKGROUND

Deep inferior epigastric perforator flap surgery usually results in postoperative pain from the donor site requiring opioids.

METHOD

We examined the effect of bupivacaine 2.5 mg/mL, 20 mL given every third hour for 72 hours postoperatively through 2 thin catheters placed on the donor site in a double-blind placebo-controlled study consisting of 2 x 20 patients.

RESULTS

The bupivacaine group had significantly reduced pain at rest and during coughing. The placebo group needed 2 to 3 times more opioids in the 72-hour observation period. No difference was seen in the frequency of nausea or the consumption of antiemetic drugs.

CONCLUSION

We conclude that intermittent delivery of bupivacaine at the abdominal donor site significantly reduces the postoperative pain and need for narcotic rescue medication.