Acute pain intensity monitoring with the classification of multiple physiological parameters

Current acute pain intensity assessment tools are mainly based on self-reporting by patients, which is impractical for non-communicative, sedated or critically ill patients. In previous studies, various physiological signals have been observed qualitatively as a potential pain intensity index. On the basis of that, this study aims at developing a continuous pain monitoring method with the classification of multiple physiological parameters. Heart rate (HR), breath rate (BR), galvanic skin response (GSR) and facial surface electromyogram were collected from 30 healthy volunteers under thermal and electrical pain stimuli. The collected samples were labelled as no pain, mild pain or moderate/severe pain based on a self-reported visual analogue scale. The patterns of these three classes were first observed from the distribution of the 13 processed physiological parameters. Then, artificial neural network classifiers were trained, validated and tested with the physiological parameters. The average classification accuracy was 70.6%. The same method was applied to the medians of each class in each test and accuracy was improved to 83.3%. With facial electromyogram, the adaptivity of this method to a new subject was improved as the recognition accuracy of moderate/severe pain in leave-one-subject-out cross-validation was promoted from 74.9 ± 21.0 to 76.3 ± 18.1%. Among healthy volunteers, GSR, HR and BR were better correlated to pain intensity variations than facial muscle activities. The classification of multiple accessible physiological parameters can potentially provide a way to differentiate among no, mild and moderate/severe acute experimental pain.

A multinational, drug utilization study to investigate the use of dexmedetomidine (Dexdor®) in clinical practice in the EU

Aims

Dexmedetomidine (dexdor®) is approved in the European Union (EU) for sedation of adults in the intensive care unit (ICU). The present observational, retrospective study was requested by the European Medicines Agency to investigate dexmedetomidine use in clinical practice, with a particular focus on off‐label use, including the paediatric population.

Methods

Study countries and sites were chosen from those with highest dexmedetomidine use, based on sales. Site selection (blind) was conducted by a multispecialist, independent group. Anonymized data on demographics, treatment indication, dexmedetomidine dosing, concomitant medications and treatment effectiveness were collected retrospectively from records of all dexmedetomidine‐treated patients at the site during the enrolment period. Informed consent was waived, to avoid influencing the prescribing of dexmedetomidine. Recruitment was completed within 18 months of first site initiation.

Results

Data from 2000 patients were collected from 16 hospitals in four EU countries (Finland 750, Poland 505, Germany 470, Austria 275). The median age was 62 years, with more males (70.2%) than females. Dexmedetomidine was primarily used in the adult ICU (86.0%) for ICU sedation (78.6%) and mostly dosed according the product label. The intended sedative effect was obtained in 84.9% of administrations. Paediatric use (5.9% of patients, mostly in Austria and Finland) occurred mainly in the adult or paediatric ICU (75.6%) for sedation (67.2%).

Conclusions

Overall, most patients were treated with dexmedetomidine according to the product labelling. Use in children was limited but significant and similar in scope to that in adults. Administrations not fully according to the product labelling usually occurred in an ICU environment and reflected extensively investigated clinical uses of dexmedetomidine.

The Internet of Things for basic nursing care-A scoping review

BACKGROUND

The novel technology of the Internet of Things (IoT) connects objects to the Internet and its most advanced applications refine obtained data for the user. We propose that Internet of Things technology can be used to promote basic nursing care in the hospital environment by improving the quality of care and patient safety.

OBJECTIVES

To introduce the concept of Internet of Things to nursing audience by exploring the state of the art of Internet of Things based technology for basic nursing care in the hospital environment.

DATA SOURCES AND REVIEW METHODS

Scoping review methodology following Arksey & O'Malley's stages from one to five were used to explore the extent, range, and nature of current literature. We searched eight databases using predefined search terms. A total of 5030 retrievals were found which were screened for duplications and relevancy to the study topic. 265 papers were chosen for closer screening of the abstracts and 93 for full text evaluation. 62 papers were selected for the review. The constructs of the papers, the Internet of Things based innovations and the themes of basic nursing care in hospital environment were identified.

RESULTS

Most of the papers included in the review were peer-reviewed proceedings of technological conferences or articles published in technological journals. The Internet of Things based innovations were presented in methodology papers or tested in case studies and usability assessments. Innovations were identified in several topics in four basic nursing care activities: comprehensive assessment, periodical clinical reassessment, activities of daily living and care management.

CONCLUSIONS

Internet of Things technology is providing innovations for the use of basic nursing care although the innovations are emerging and still in early stages. Internet of things is yet vaguely adopted in nursing. The possibilities of the Internet of Things are not yet exploited as well as they could. Nursing science might benefit from deeper involvement in engineering research in the area of health.

Prevalence of life-supporting prolonged invasive ventilation support in Finland

BACKGROUND

There is no comprehensive data in our country on the prevalence of life-supporting prolonged invasive ventilation support. The objective of the survey was to clarify in all hospital districts of continental Finland the prevalence of patients who were dependent on invasive ventilation support, and the disease leading to the treatment.

PATIENTS AND METHODS

The KOTIVEHNO 2015 survey was carried out as population-based cross-sectional study by sending a questionnaire to all doctors in charge of prolonged invasive ventilation support. The questionnaires were used to collect data on the patients within care on 1st January, 2017.

RESULTS

The prevalence of life-supporting prolonged invasive ventilation support in Finland among the population aged over 16 years or more was 2/4 patients/100,000 habitants. Altogether 107 patients were within the care. There was variation in the prevalence among the hospital districts. Of the patients, 24% were affected with a motoneuron disease, in 18% the cause was spinal cord injury, 15% suffered from Duchenne's muscular dystrophy, and the rest had some other rare neurological disease.

CONCLUSIONS

Life-supporting prolonged invasive ventilation support is rare in Finland. The treatment is associated with neuromuscular diseases causing respiratory insufficiency, and with spinal cord injuries.

Productivity benchmarks for operative service units

BACKGROUND

Easily accessible reliable information is crucial for strategic and tactical decision-making on operative processes. We report development of an analysis tool and resulting metrics for benchmarking purposes at a Finnish university hospital.

METHODS

The analysis tool is based on data collected in a resource management system and an in-house cost-reporting database.

RESULTS

The exercise reports key metrics for four operative service units and six surgical units from 2014 and the change from year 2013. Productivity, measured as total costs per total hours, ranged from 658 to 957 €/h and utilization of the total available resource hours at the service unit level ranged from 66% to 74%. The lowest costs were in a unit running only regular working hour shifts, whereas the highest costs were in a unit operating on 24/7 basis. The tool includes additional metrics on operating room (OR) scheduling and monthly data to support more detailed analysis.

CONCLUSION

This report provides the hospital management with an improved and detailed overview of its operative service units and the surgical process and related costs. The operating costs are associated with on call duties, size of operative service units, and the requirements of the surgeries. This information aids in making mid- to long range decisions on managing OR capacity.

[Supraventricular tachycardia during pregnancy]

An increase in cardiac output during pregnancy increases the risk of arrhythmias for the expectant mother. Supraventricular tachycardia (SVT) underlies the sensations of arrhythmia in a pregnant woman in as many as one sixth of the cases. Vagal nerve (n. vagus) stimulation and adenosine serve as first-line treatment, but electrical cardioversion is likely to be a safe alternative as well. We describe a case in which the SVT of a woman in the third trimester of pregnancy was unresponsive to vagal nerve stimulation and pharmacological treatments. Electrical cardioversion was successfully performed after having a cesarean section procedure.

Sedation options for the morbidly obese intensive care unit patient: a concise survey and an agenda for development

Background: We offer some perspectives and commentary on the sedation of obese patients in the intensive care unit (ICU). Discussion: Sedation in morbidly obese patients should conform to the same broad principles now current in ICU practice. These include a general presumption against benzodiazepines as first-line agents. Opioids should be avoided in any situation where spontaneous breathing is required. Remifentanil is the preferred agent where continuous stable opioid levels using an infusion are required, because of its lack of context-sensitive accumulation. Volatile anaesthetics may be an option for the same reason but there are no substantial, controlled demonstrations of effectiveness/safety in short-term use in the ICU setting. Propofol is a valuable resource in the morbidly obese patients but the duration of continuous sedation should not exceed 6 days, in order to avoid propofol infusion syndrome. Alpha-2 agonists offer a range of theoretically positive features for the sedation of morbidly obese patients, but at present there is a lack of pharmacokinetic data and a critical mass of high-grade clinical data. Dexmedetomidine has the attraction of not causing respiratory depression or obstructive breathing during sedation and its sympatholytic effects should help deliver stable blood pressure and heart rate. Ketamine has a poor tolerability profile in adults so its use in the ICU context is largely confined to paediatrics. Conclusion: None of the agents currently available is ideal for every situation encountered in the management of morbidly obese patients. This article identifies additional research needed to place sedation practice of obese patients on a more systematic footing.

Sedation options for the morbidly obese intensive care unit patient: a concise survey and an agenda for development

Background

We offer some perspectives and commentary on the sedation of obese patients in the intensive care unit (ICU).

Discussion

Sedation in morbidly obese patients should conform to the same broad principles now current in ICU practice. These include a general presumption against benzodiazepines as first-line agents. Opioids should be avoided in any situation where spontaneous breathing is required. Remifentanil is the preferred agent where continuous stable opioid levels using an infusion are required, because of its lack of context-sensitive accumulation. Volatile anaesthetics may be an option for the same reason but there are no substantial, controlled demonstrations of effectiveness/safety in short-term use in the ICU setting. Propofol is a valuable resource in the morbidly obese patients but the duration of continuous sedation should not exceed 6 days, in order to avoid propofol infusion syndrome. Alpha-2 agonists offer a range of theoretically positive features for the sedation of morbidly obese patients, but at present there is a lack of pharmacokinetic data and a critical mass of high-grade clinical data. Dexmedetomidine has the attraction of not causing respiratory depression or obstructive breathing during sedation and its sympatholytic effects should help deliver stable blood pressure and heart rate. Ketamine has a poor tolerability profile in adults so its use in the ICU context is largely confined to paediatrics.

Conclusion

None of the agents currently available is ideal for every situation encountered in the management of morbidly obese patients. This article identifies additional research needed to place sedation practice of obese patients on a more systematic footing.

[Amyotrophic lateral sclerosis and respiratory insufficiency]

Amyotrophic lateral sclerosis (ALS) is a disease causing degeneration of motor neurons, without any curative treatment. The most common cause of death is respiratory arrest due to atrophy of the respiratory musculature. ALS-associated respiratory insufficiency differs in mechanism from the more common causes of dyspnea, such as diseases of pulmonary or cardiac origin. Recognizing the respiratory insufficiency can be challenging for a clinician. It should be possible to predict the development of respiratory insufficiency in order to avoid leaving the treatment decisions concerning respiratory insufficiency to emergency services. Noninvasive ventilatory support can be used to alleviate the patient's dyspnea. It is actually recommended as the first-line treatment of ALS-associated respiratory insufficiency.

Sedation in non-invasive ventilation: do we know what to do (and why)?

This review examines some of the issues encountered in the use of sedation in patients receiving respiratory support from non-invasive ventilation (NIV). This is an area of critical and intensive care medicine where there are limited (if any) robust data to guide the development of best practice and where local custom appears to exert a strong influence on patterns of care. We examine aspects of sedation for NIV where the current lack of structure may be contributing to missed opportunities to improve standards of care and examine the existing sedative armamentarium. No single sedative agent is currently available that fulfils the criteria for an ideal agent but we offer some observations on the relative merits of different agents as they relate to considerations such as effects on respiratory drive and timing, and airways patency. The significance of agitation and delirium and the affective aspect(s) of dyspnoea are also considered.We outline an agenda for placing the use of sedation in NIV on a more systematic footing, including clearly expressed criteria and conditions for terminating NIV and structural and organizational conditions for prospective multicentre trials.

Postoperative fentanyl patch versus subacromial bupivacaine infusion in arthroscopic shoulder surgery

PURPOSE

The purpose of our study was to compare the effectiveness of subacromial bupivacaine infusion and a transdermal fentanyl patch in the treatment of postoperative pain after arthroscopic shoulder surgery.

METHODS

Sixty patients with rotator cuff disease scheduled for elective arthroscopic shoulder surgery were enrolled in the study. For the treatment of postoperative pain, 30 patients constituted group F and received a 12.0-μg/h fentanyl patch for 72 hours and saline solution infusion in a subacromial manner at the rate of 4 mL/h. The remaining 30 patients constituted group B and received a placebo patch and an infusion of 2.5-mg/mL bupivacaine in a subacromial manner for 72 hours. The primary outcome measure was the postoperative numerical rating scale pain score. The consumption of opioids, ibuprofen, and acetaminophen was also recorded. The Constant scores and general recovery were followed up until the 90th postoperative day.

RESULTS

There was no statistically significant difference in the numerical rating scale scores (P = .60) between the groups. No differences in the use of rescue analgesic were observed except that the patients receiving bupivacaine used more ibuprofen (median, 1,200 mg v 600 mg) during the day of surgery (P = .042). No difference was found in general recovery between the groups.

CONCLUSIONS

A fentanyl patch delivering 12-μg/h fentanyl offers an easy and safe treatment option as a part of multimodal analgesia with few adverse effects in the treatment of postoperative pain in a carefully selected patient group after arthroscopic shoulder surgery.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Using respiratory rate and thoracic movement to assess respiratory insufficiency in amyotrophic lateral sclerosis: a preliminary study

Background

Hypoventilation due to respiratory insufficiency is the most common cause of death in amyotrophic lateral sclerosis (ALS) and non-invasive ventilation (NIV) can be used as a palliative treatment. The current guidelines recommend performing spirometry, and recording nocturnal oxyhemoglobin saturation and arterial blood gas analysis to assess the severity of the hypoventilation. We examined whether the respiratory rate and thoracic movement were reliable preliminary clinical signs in the development of respiratory insufficiency in patients with ALS.

Methods

We measured the respiratory rate and thoracic movement, performed respiratory function tests and blood gas analysis, and recorded subjective hypoventilation symptoms in 42 ALS patients over a 7-year period. We recommended NIV if the patient presented with hypoventilation matching the current guidelines. We divided patients retrospectively into two groups: those to whom NIV was recommended within 6 months of the diagnosis (Group 1) and those to whom NIV was recommended 6 months after the diagnosis (Group 2). We used the Mann Whitney U test for comparisons between the two groups.

Results

The mean partial pressure of arterial carbon dioxide in the morning in Group 1 was 6.3 (95% confidence interval 5.6–6.9) kPa and in Group 2 5.3 (5.0–5.6) kPa (p = 0.007). The mean respiratory rate at the time of diagnosis in Group 1 was 21 (18–24) breaths per minute and 16 (14–18) breaths per minute in Group 2 (p = 0.005). The mean thoracic movement was 2.9 (2.2–3.6) cm in Group 1 and 4.0 (3.4–4.8) cm in Group 2 (p = 0.01). We observed no other differences between the groups.

Conclusions

Patients who received NIV within six months of the diagnosis of ALS had higher respiratory rates and smaller thoracic movement compared with patients who received NIV later. Further studies with larger numbers of patients are needed to establish if these measurements can be used as a marker of hypoventilation in ALS.

Pharmacokinetics of prolonged infusion of high-dose dexmedetomidine in critically ill patients

INTRODUCTION

Only limited information exists on the pharmacokinetics of prolonged (> 24 hours) and high-dose dexmedetomidine infusions in critically ill patients. The aim of this study was to characterize the pharmacokinetics of long dexmedetomidine infusions and to assess the dose linearity of high doses. Additionally, we wanted to quantify for the first time in humans the concentrations of H-3, a practically inactive metabolite of dexmedetomidine.

METHODS

Thirteen intensive care patients with mean age of 57 years and Simplified Acute Physiology Score (SAPS) II score of 45 were included in the study. Dexmedetomidine infusion was commenced by using a constant infusion rate for the first 12 hours. After the first 12 hours, the infusion rate of dexmedetomidine was titrated between 0.1 and 2.5 μg/kg/h by using predefined dose levels to maintain sedation in the range of 0 to -3 on the Richmond Agitation-Sedation Scale. Dexmedetomidine was continued as long as required to a maximum of 14 days. Plasma dexmedetomidine and H-3 metabolite concentrations were measured, and pharmacokinetic variables were calculated with standard noncompartmental methods. Safety and tolerability were assessed by adverse events, cardiovascular signs, and laboratory tests.

RESULTS

The following geometric mean values (coefficient of variation) were calculated: length of infusion, 92 hours (117%); dexmedetomidine clearance, 39.7 L/h (41%); elimination half-life, 3.7 hours (38%); and volume of distribution during the elimination phase, 223 L (35%). Altogether, 116 steady-state concentrations were found in 12 subjects. The geometric mean value for clearance at steady state was 53.1 L/h (55%). A statistically significant linear relation (r2 = 0.95; P < 0.001) was found between the areas under the dexmedetomidine plasma concentration-time curves and cumulative doses of dexmedetomidine. The elimination half-life of H-3 was 9.1 hours (37%). The ratio of AUC0-∞ of H-3 metabolite to that of dexmedetomidine was 1.47 (105%), ranging from 0.29 to 4.4. The ratio was not statistically significantly related to the total dose of dexmedetomidine or the duration of the infusion.

CONCLUSIONS

The results suggest linear pharmacokinetics of dexmedetomidine up to the dose of 2.5 μg/kg/h. Despite the high dose and prolonged infusions, safety findings were as expected for dexmedetomidine and the patient population.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00747721.

Consciousness lost and found: subjective experiences in an unresponsive state

Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as "responsiveness to the environment" seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower "depth of sedation" as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.

Pharmacokinetics of intravenous paracetamol in elderly patients

BACKGROUND AND OBJECTIVES

Intravenous paracetamol (N-acetyl-paraminophenol, acetaminophen) is a widely used nonopioid analgesic which has become popular in the treatment of pain in many patient groups, including the elderly. Although intravenous paracetamol has been studied widely in clinical analgesia studies, there is little information on its pharmacokinetics in the elderly. We designed this study to determine the pharmacokinetics of intravenous paracetamol in very old patients and to compare them with that of younger patients. We also considered the effect of adenosine triphosphate-binding cassette G2 protein (ABCG2) genotype and renal function on paracetamol pharmacokinetics in these patients.

METHODS

We compared the pharmacokinetics of intravenous paracetamol in four groups of ten patients, aged 20-40, 60-70, 70-80 and 80-90 years, undergoing orthopaedic surgery. Paracetamol 1000 mg was given by infusion over 15 minutes. Plasma concentrations of paracetamol and its glucuronide and sulphate conjugates were measured for 24 hours with a high-performance liquid chromatographic method and ABCG2 genotype was determined. Glomerular filtration rate (GFR) was estimated from age, sex and serum creatinine of the patient.

RESULTS

In the group aged 80-90 years, the mean value of the area under the plasma concentration-time curve extrapolated to infinity (AUC(∞)) of paracetamol was 54-68% higher than in the two youngest groups. Paracetamol clearance showed a statistically significant dependence on age group, whereas volume of distribution during elimination and elimination half-life were associated with age group and sex, respectively. Based on mean AUC(∞) of paracetamol glucuronide and paracetamol sulphate, the oldest patients had 1.3- to 1.5-fold greater exposure to these metabolites than patients aged 20-40 years. ABCG2 genotype did not affect paracetamol pharmacokinetics. There was a linear correlation between the values of AUC(∞) of paracetamol, its glucuronide and sulphate metabolites and GFR.

CONCLUSION

Age and sex are important factors affecting the pharmacokinetics of paracetamol. The higher the age of the patient, the higher is the exposure to paracetamol. Female sex is associated with increased paracetamol concentrations but ABCG2 genotype does not seem to affect paracetamol pharmacokinetics. Trial registration number (EudraCT): 2006-001917-14.

Renal effects of dexmedetomidine during coronary artery bypass surgery: a randomized placebo-controlled study

Background

Dexmedetomidine, an alpha₂-adrenoceptor agonist, has been evaluated as an adjunct to anesthesia and for the delivery of sedation and perioperative hemodynamic stability. It provokes dose-dependent and centrally-mediated sympatholysis. Coronary artery bypass grafting (CABG) with extracorporeal circulation is a stressful procedure increasing sympathetic nervous system activity which could attenuate renal function due the interrelation of sympathetic nervous system, hemodynamics and renal function. We tested the hypothesis that dexmetomidine would improve kidney function in patients undergoing elective CABG during the first two postoperative days.

Methods

This was a double-blind, randomized, parallel-group study. Patients with normal renal function and scheduled for elective CABG were randomized to placebo or to infusion of dexmedetomidine to achieve a pseudo steady-state plasma concentration of 0.60 ng/ml. The infusion was started after anesthesia induction and continued until 4 h after surgery. The primary endpoint was creatinine clearance. Other variables included urinary creatinine and output, fractional sodium and potassium excretion, urinary potassium, sodium and glucose, serum and urinary osmolality and plasma catecholamine concentrations. The data were analyzed with repeated-measures ANOVA or Cochran-Mantel-Haenszel test.

Results

Sixty-six of 87 randomized patients were evaluable for analysis. No significant between-group differences were recorded for any indices of renal function except for a mean 74% increase in urinary output with dexmedetomidine in the first 4 h after insertion of a urinary catheter (p < 0.001). Confidence interval examination revealed that the sample size was large enough for the no-difference statement for creatinine clearance.

Conclusions

Use of intravenous dexmedetomidine did not alter renal function in this cohort of relatively low-risk elective CABG patients but was associated with an increase in urinary output.

This study was carried out in 1994-1997 and was thus not registered.

Bioavailability of dexmedetomidine after intranasal administration

PURPOSE

The aim of this proof-of-concept study was to characterize the pharmacokinetics and pharmacodynamics of intranasal dexmedetomidine compared with its intravenous administration in a small number of healthy volunteers.

METHODS

Single doses of 84 μg of dexmedetomidine were given once intravenously and once intranasally to seven healthy men. Plasma dexmedetomidine concentrations were measured for 10 h, and pharmacokinetic variables were calculated with standard noncompartmental methods. Heart rate, blood pressure, concentrations of adrenaline and noradrenaline in plasma, and central nervous system drug effects (with the Maddox wing, Bispectral Index, and three visual analog scales) were monitored to assess the pharmacological effects of dexmedetomidine.

RESULTS

Six individuals were included in the analyses. Following intranasal administration, peak plasma concentrations of dexmedetomidine were reached in 38 (15-60) min and its absolute bioavailability was 65% (35-93%) (medians and ranges). Pharmacological effects were similar with both routes of administration, but their onset was more rapid after intravenous administration.

CONCLUSIONS

Dexmedetomidine is rather rapidly and efficiently absorbed after intranasal administration. Compared with intravenous administration, intranasal administration may be a feasible alternative in patients requiring light sedation.

Dexmedetomidine inhibits gastric emptying and oro-caecal transit in healthy volunteers

BACKGROUND

Dexmedetomidine is a potent and selective α2-adrenoceptor agonist used for perioperative and intensive care sedation with certain beneficial qualities. However, based on preclinical observations, it might inhibit gastric emptying and gastrointestinal transit, which could result in unwanted effects in intensive care patients. This study evaluated the effects of dexmedetomidine on gastric emptying and oro-caecal transit time in healthy volunteers.

METHODS

Twelve healthy male subjects were given 1 µg kg(-1) of dexmedetomidine i.v. over 20 min followed by a continuous i.v. infusion of 0.7 µg kg(-1) h(-1) for 190 min. For comparison, subjects were also given 0.10 mg kg(-1) of morphine hydrochloride i.v. over 20 min and a placebo infusion in a randomized order. Gastric emptying was assessed with the paracetamol absorption test and oro-caecal transit time with the hydrogen breath test.

RESULTS

The time to maximum paracetamol concentration in plasma was significantly longer, maximum paracetamol concentration was significantly lower, the area under the plasma paracetamol concentration-time curve was significantly smaller, and oro-caecal transit time was significantly longer during dexmedetomidine infusion compared with morphine or placebo infusion.

CONCLUSIONS

Dexmedetomidine markedly inhibits gastric emptying and gastrointestinal transit in healthy volunteers.

Predictive equations over-estimate the resting energy expenditure in amyotrophic lateral sclerosis patients who are dependent on invasive ventilation support

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a form of degenerative motor neuron disease. At the end stage of the disease artificial feeding is often required. Nevertheless, very little is known about the energy demand of those ALS patients who are chronically dependent on tracheostomy intermittent positive pressure ventilation. The objective of our study was to clarify the resting energy expenditure (REE) in mechanically ventilated ALS patients.

METHODS

We measured the REE of five ALS patients (four men, one female) twice during a 12 month-period using indirect calorimetry with two sampling flow settings (40 L/min and 80 L/min). The measured REEs (mREE) were compared with values calculated using five different predictive equations.

RESULTS

The mean (± SD) of all mREEs was 1130 ± 170 kcal/d. The measurements with different flow settings and at different time instances provided similar results. The mean of mREEs was 33.6% lower, as compared to the mean calculated with five different predictive equations REE (p < 0.001). Each of the predictive equations over-estimated the REE.

CONCLUSIONS

The mREE values were significantly lower for every patient than all the predicted ones. Determination of daily nutrition with predictive equations may therefore lead in mis-estimation of energy requirements. Because ALS patients may live years with artificial ventilation their nutritional support should be based on individual measurements. However, further study is needed due to the small number of subjects.

Highly variable pharmacokinetics of dexmedetomidine during intensive care: a case report

INTRODUCTION

Dexmedetomidine is a selective and potent alpha2-adrenoceptor agonist licensed for use in the sedation of patients initially ventilated in intensive care units at a maximum dose rate of 0.7 mug/kg/h administered for up to 24 hours. Higher dose rates and longer infusion periods are sometimes required to achieve sufficient sedation. There are some previous reports on the use of long-term moderate to high-dose infusions of dexmedetomidine in patients in intensive care units, but none of these accounts have cited dexmedetomidine plasma concentrations.

CASE PRESENTATION

We describe the case of a 42-year-old Caucasian woman with severe hemorrhagic pancreatitis following laparoscopic cholecystectomy who received dexmedetomidine for 24 consecutive days at a maximum dose rate of 1.9 mug/kg/h. Samples for the measurement of dexmedetomidine concentrations in her plasma were drawn at intervals of eight hours. On average, the observed plasma concentrations were well in accordance with previous knowledge on the pharmacokinetics of dexmedetomidine. There was, however, marked variability in the concentration of dexmedetomidine in her plasma despite a stable infusion rate.

CONCLUSION

The pharmacokinetics of dexmedetomidine appears to be highly variable during intensive care.

Effects of Xenon Anesthesia on Cerebral Blood Flow in Humans

Background

Animal studies have demonstrated a strong neuroprotective property of xenon. Its usefulness in patients with cerebral pathology could be compromised by deleterious effects on regional cerebral blood flow (rCBF).

Methods

15O-labeled water was used to determine rCBF in nine healthy male subjects at baseline and during 1 minimum alveolar concentration (MAC) of xenon (63%). Anesthesia was based solely on xenon. Absolute changes in rCBF were quantified using region-of-interest analysis and voxel-based analysis.

Results

Mean arterial blood pressure and arterial partial pressure for carbon dioxide remained unchanged. The mean (+/-SD) xenon concentration during anesthesia was 65.2+/-2.3%. Xenon anesthesia decreased absolute rCBF by 34.7+/-9.8% in the cerebellum (P&lt;0.001), by 22.8+/-10.4% in the thalamus (P=0.001), and by 16.2+/-6.2% in the parietal cortex (P&lt;0.001). On average, xenon anesthesia decreased absolute rCBF by 11.2+/-8.6% in the gray matter (P=0.008). A 22.1+/-13.6% increase in rCBF was detected in the white matter (P=0.001). Whole-brain voxel-based analysis revealed widespread cortical reductions and increases in rCBF in the precentral and postcentral gyri.

Conclusions

One MAC of xenon decreased rCBF in several areas studied. The greatest decreases were detected in the cerebellum, the thalamus and the cortical areas. Increases in rCBF were observed in the white matter and in the pre- and postcentral gyri. These results are in clear contradiction with ketamine, another N-methyl-D-aspartate antagonist and neuroprotectant, which induces a general increase in cerebral blood flow at anesthetic concentrations.

Dexmedetomidine as an adjuvant in the treatment of alcohol withdrawal delirium: a case report

In this case report, even a moderate dose of dexmedetomidine, a very selective alpha(2)-adrenergic agent, resulted in a rapid response to alcohol withdrawal delirium after the standard treatment. Psychiatrists should be aware of this relatively new drug that provides advantages over clonidine, heavy sedation and secondary restraints. Dexmedetomidine should be further evaluated in the treatment of specific forms of aggressive behavior and complicated withdrawal states.

Ketoprofen and tramadol for analgesia during early recovery after tonsillectomy in children

BACKGROUND

Pain following tonsillectomy is often intense. Nonsteroidal anti-inflammatory drugs and opioids are effective, but both can cause adverse effects. Tramadol may be a viable alternative for post-tonsillectomy pain. This study was designed to compare the analgesic effects of ketoprofen and tramadol during the early recovery period after tonsillectomy.

METHODS

Forty-five ASA class I children (9-15 years) were randomized to receive either saline, ketoprofen (2 mg.kg(-1)) or tramadol (1 mg.kg(-1)) after induction of anesthesia. Upon completion of surgery, the study treatment was continued as a 6 h intravenous (i.v.) infusion of another dose of saline, ketoprofen (2 mg.kg(-1)) or tramadol (1 mg.kg(-1)). Postoperatively, each patient received rescue analgesia with patient-controlled analgesia (PCA) device programmed to deliver 0.5 microg.kg(-1) bolus doses of fentanyl. Postoperative pain was assessed using Visual Analog Scale (VAS) during swallowing. Intraoperative blood loss was measured.

RESULTS

The total number of requests of PCA-fentanyl was significantly less in ketoprofen group compared with tramadol and placebo groups (P = 0.035 and P = 0.049, respectively, in pairwise comparisons) and the VAS scores for pain were significantly lower in ketoprofen group compared with tramadol (P = 0.044) or placebo groups (P = 0.018) during the first six postoperative hours. Measured intraoperative blood loss was greater in ketoprofen-treated patients than in those receiving placebo (P = 0.029).

CONCLUSION

A dose of 4 mg.kg(-1) of i.v. ketoprofen provided good pain relief with moderate supplemental PCA-fentanyl requirements during the first six postoperative hours after tonsillectomy in children whereas the effects of 2 mg.kg(-1) of i.v. tramadol did not differ from those of placebo.

Perioperative use of α2-adrenoceptor agonists and the cardiac patient

The centrally acting alpha2-adrenoceptor agonists clonidine and dexmedetomidine have been used with success to provide haemodynamic stability for patients undergoing surgery. Particularly in the case of patients with overt or underlying cardiac disease the actions of alpha2-adrenoceptor agonists, which include maintenance of stable systemic blood pressure and low heart rate and a reduction in overall oxygen consumption, can be expected to reduce the risk of procedure-related cardiac events. This expectation has been corroborated in clinical trials with clonidine, dexmedetomidine and mivazerol and meta-analyses; additional large controlled trials would be instructive in establishing a robust estimate of the scale of the benefit. In addition, alpha2-adrenoceptor agonists used as premedication have been shown to substantially reduce anaesthetic requirements among surgical patients, and the use of these agents has been associated with a reduced risk of postoperative delirium, which may be expected to improve considerably the postoperative course for at-risk patients. Dexmedetomidine is the only alpha2-adrenoceptor agonist currently approved for use in the intensive care unit. A distinctive feature of dexmedetomidine in that setting is that in addition to haemodynamic stability it confers a distinctive and advantageous quality of sedation: patients are tranquil but responsive to requests from attending staff. This review examines the pharmacological principles underlying the use of alpha2-adrenoceptor agonists as adjuncts to surgery and clinical experience in that indication.

Gene expression of pulmonary cytokines after sevoflurane or thiopentone anaesthesia in pigs

BACKGROUND

Volatile anaesthetics have diverse inflammatory effects on the lungs. They increase gene expression of some pro-inflammatory cytokines in alveolar macrophages whereas in alveolar type II cells they seem to decrease secretion and gene expression of pro-inflammatory cytokines. We have previously detected increased leukotriene C4, nitrate and nitrite concentrations in bronchoalveolar lavage fluid after sevoflurane anaesthesia. In the current study, we measured gene expression of inflammatory cytokines in the lung tissue and plasma concentrations of cytokines in pigs after thiopentone or sevoflurane anaesthesia.

METHODS

Sixteen pigs were randomly selected to receive either a continuous thiopentone infusion (control group, n = 8) or sevoflurane (n = 8) at 4.0% inspiratory concentration (1.5 MAC) in air for 6 h. Tissue samples were collected at the end of the study for measurement of gene expression of inflammatory cytokines. Blood samples were collected during anaesthesia for measurement of plasma cytokine concentrations.

RESULTS

Compared with thiopentone anaesthesia, lower gene expression of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in lung tissue was observed after sevoflurane anaesthesia. Of measured cytokines IL-1beta, TNF-alpha, IL-6, IL-8 and IL-10 only plasma concentrations of IL-6 could be measured during the study without a difference between the groups.

CONCLUSION

Lower gene expression of TNF-alpha and IL-1beta was found in the intact porcine lung tissue after sevoflurane anaesthesia compared with thiopentone anaesthesia. Clinical significance of this finding is unknown.

Isobaric bupivacaine via spinal catheter for hip replacement surgery: ED50 and ED95 dose determination

BACKGROUND

Continuous spinal anaesthesia with spinal catheters allows incremental dosing of the local anaesthetic and, consequently, less haemodynamic change. However, little is known about the required doses. Therefore, we designed a study to assess the local anaesthetic doses of isobaric bupivacaine which were effective in 50% (ED50) and 95% (ED95) of patients undergoing hip replacement surgery.

METHODS

Forty-eight patients undergoing hip replacement surgery were randomly allocated to one of six possible groups of eight patients to receive 6, 7, 8, 9, 10 or 12 mg of isobaric bupivacaine in a double-blind manner. The ED50 and ED95 values were calculated by a logistic regression model. The position of the spinal catheter tip was confirmed by X-rays.

RESULTS

The ED50 and ED95 values were 7.1 mg (95% confidence interval, 6.0-8.4) and 12.3 mg (95% confidence interval, 8.9-15.7), respectively. The location of the tip of the intrathecal catheter had no effect on local anaesthetic requirements. Eight patients required ephedrine after anaesthesia induction and a further 11 patients required ephedrine for correction of hypotension during surgery.

CONCLUSION

The observed ED50 and ED95 values may guide us to use small doses of isobaric bupivacaine for hip replacement surgery. Hypotension is still possible even if low doses of isobaric bupivacaine are used.

S -Ketamine Anesthesia Increases Cerebral Blood Flow in Excess of the Metabolic Needs in Humans

Background

Animal studies have demonstrated neuroprotective properties of S-ketamine, but its effects on cerebral blood flow (CBF), metabolic rate of oxygen (CMRO2), and glucose metabolic rate (GMR) have not been comprehensively studied in humans.

Methods

Positron emission tomography was used to quantify CBF and CMRO2 in eight healthy male volunteers awake and during S-ketamine infusion targeted to subanesthetic (150 ng/ml) and anesthetic (1,500-2,000 ng/ml) concentrations. In addition, subjects' GMRs were assessed awake and during anesthesia. Whole brain estimates for cerebral blood volume were obtained using kinetic modeling.

Results

The mean +/- SD serum S-ketamine concentration was 159 +/- 21 ng/ml at the subanesthetic and 1,959 +/- 442 ng/ml at the anesthetic levels. The total S-ketamine dose was 10.4 mg/kg. S-ketamine increased heart rate (maximally by 43.5%) and mean blood pressure (maximally by 27.0%) in a concentration-dependent manner (P = 0.001 for both). Subanesthetic S-ketamine increased whole brain CBF by 13.7% (P = 0.035). The greatest regional CBF increase was detected in the anterior cingulate (31.6%; P = 0.010). No changes were detected in CMRO2. Anesthetic S-ketamine increased whole brain CBF by 36.4% (P = 0.006) but had no effect on whole brain CMRO2 or GMR. Regionally, CBF was increased in nearly all brain structures studied (greatest increase in the insula 86.5%; P &lt; 0.001), whereas CMRO2 increased only in the frontal cortex (by 15.7%; P = 0.007) and GMR increased only in the thalamus (by 11.7%; P = 0.010). Cerebral blood volume was increased by 51.9% (P = 0.011) during anesthesia.

Conclusions

S-ketamine-induced CBF increases exceeded the minor changes in CMRO2 and GMR during anesthesia.

Minimum effective local anaesthetic dose of isobaric levobupivacaine and ropivacaine administered via a spinal catheter for hip replacement surgery

BACKGROUND

Continuous spinal anaesthesia with spinal catheters allows incremental dosing of local anaesthetic and, consequently, less haemodynamic changes. However, little is known about the required doses. Therefore, we designed a study to assess the minimum effective local anaesthetic dose (MLAD) of levobupivacaine and ropivacaine in this context.

METHODS

Forty-one patients undergoing hip replacement surgery were randomly allocated to one of the two local anaesthetic groups in a double-blind manner. The initial dose of local anaesthetic was determined by the response of the previous patient: the effective dose resulted in a 1 mg decrease in the dose of levobupivacaine or ropivacaine, and an ineffective dose resulted in a 1 mg increase. The MLAD was calculated by the Dixon up-and-down method.

RESULTS

The MLAD of levobupivacaine was 11.7 mg (95% CI, 11.1-12.4) and that of ropivacaine 12.8 mg (95% CI, 12.2-13.4).

CONCLUSIONS

These doses are significantly smaller than doses reported before for single-shot spinal anaesthesia. Continuous spinal anaesthesia allows the use of relatively small doses of local anaesthetic.

Effects of subanesthetic ketamine on regional cerebral glucose metabolism in humans

BACKGROUND

The authors have recently shown with positron emission tomography that subanesthetic doses of racemic ketamine increase cerebral blood flow but do not affect oxygen consumption significantly. In this study, the authors wanted to assess the effects of racemic ketamine on regional glucose metabolic rate (rGMR) in similar conditions to establish whether ketamine truly induces disturbed coupling between cerebral blood flow and metabolism.

METHODS

18F-labeled fluorodeoxyglucose was used as a positron emission tomography tracer to quantify rGMR on 12 brain regions of interest of nine healthy male volunteers at baseline and during a 300-ng/ml ketamine target concentration level. In addition, voxel-based analysis was performed for the relative changes in rGMR using statistical parametric mapping.

RESULTS

The mean +/- SD measured ketamine serum concentration was 326.4+/-86.3 ng/ml. The mean arterial pressure was slightly increased (maximally by 16.4%) during ketamine infusion (P < 0.001). Ketamine increased absolute rGMR significantly in most regions of interest studied. The greatest increases were detected in the thalamus (14.6+/-15.9%; P = 0.029) and in the frontal (13.6+/-13.1%; P = 0.011) and parietal cortices (13.1+/-11.2%; P = 0.007). Absolute rGMR was not decreased anywhere in the brain. The voxel-based analysis revealed relative rGMR increases in the frontal, temporal, and parietal cortices.

CONCLUSIONS

Global increases in rGMR seem to parallel ketamine-induced increases in cerebral blood flow detected in the authors' earlier study. Therefore, ketamine-induced disturbance of coupling between cerebral blood flow and metabolism is highly unlikely. The previously observed decrease in oxygen extraction fraction may be due to nonoxidative glucose metabolism during ketamine-induced increase in glutamate release.

Effects of subanesthetic doses of ketamine on regional cerebral blood flow, oxygen consumption, and blood volume in humans

BACKGROUND

Animal experiments have demonstrated neuroprotection by ketamine. However, because of its propensity to increase cerebral blood flow, metabolism, and intracranial pressure, its use in neurosurgery or trauma patients has been questioned.

METHODS

15O-labeled water, oxygen, and carbon monoxide were used as positron emission tomography tracers to determine quantitative regional cerebral blood flow (rCBF), metabolic rate of oxygen (rCMRO2), and blood volume (rCBV), respectively, on selected regions of interest of nine healthy male volunteers at baseline and during three escalating concentrations of ketamine (targeted to 30, 100, and 300 ng/ml). In addition, voxel-based analysis for relative changes in rCBF and rCMRO2 was performed using statistical parametric mapping.

RESULTS

The mean +/- SD measured ketamine serum concentrations were 37 +/- 8, 132 +/- 19, and 411 +/- 71 ng/ml. Mean arterial pressure was slightly elevated (maximally by 15.3%, P < 0.001) during ketamine infusion. Ketamine increased rCBF in a concentration-dependent manner. In the region-of-interest analysis, the greatest absolute changes were detected at the highest ketamine concentration level in the anterior cingulate (38.2% increase from baseline, P < 0.001), thalamus (28.5%, P < 0.001), putamen (26.8%, P < 0.001), and frontal cortex (25.4%, P < 0.001). Voxel-based analysis revealed marked relative rCBF increases in the anterior cingulate, frontal cortex, and insula. Although absolute rCMRO2 was not changed in the region-of-interest analysis, subtle relative increases in the frontal, parietal, and occipital cortices and decreases predominantly in the cerebellum were detected in the voxel-based analysis. rCBV increased only in the frontal cortex (4%, P = 0.022).

CONCLUSIONS

Subanesthetic doses of ketamine induced a global increase in rCBF but no changes in rCMRO2. Consequently, the regional oxygen extraction fraction was decreased. Disturbed coupling of cerebral blood flow and metabolism is, however, considered unlikely because ketamine has been previously shown to increase cerebral glucose metabolism. Only a minor increase in rCBV was detected. Interestingly, the most profound changes in rCBF were observed in structures related to pain processing.

Surgical closure of patent ductus arteriosus in very-low-birth-weight infants

In many very-low-birth-weight (VLBW) infants the ductus arteriosus fails to close spontaneously, and they subsequently develop signs and symptoms of poor tissue perfusion and heart failure. This study evalutes the results of early surgical closure of patent ductus arteriosus (PDA). We retrospectively reviewed the records of all 101 VLBW infants who weighed 1,500 g or less when their PDA was surgically ligated in Turku University Hospital between 1988 and 1998. The mean gestational age at birth was 27.2 weeks and mean birth weight 963+/-239 g. The operation was performed at 12+/-8 days of age; the infants' weight at operation was 969+/-231 g and they were tracheally extubated 11+/-14 days after the operation. The surgery-related mortality was 3% (3/101) and overall mortality 10% (10/101). We conclude that surgical closure of PDA is safe and effective in VLBW infants.

Sevoflurane EC50 and EC95 values for laryngeal mask insertion and tracheal intubation in children

The laryngeal mask airway (LMA) is a simple, easy to use and safe method for airway control in children. Its insertion needs less anaesthetic, and haemodynamic responses and postoperative sequelae are less than with laryngoscopy and tracheal intubation. This study was designed to determine the end-tidal concentrations of sevoflurane where 50% (EC50) and 95% (EC95) of the attempts to secure the airway would be successful. We randomly assigned 40 children aged 4-12 yr undergoing general surgery to either LMA insertion (n=20) or to laryngoscopy and tracheal intubation (n=20) under sevoflurane anaesthesia. The initial end-tidal concentration of sevoflurane for each child was determined according to the response of the previous child in the same group. Up to three attempts to secure the airway with increasing sevoflurane end-tidal concentrations in 0.3% steps were allowed for each child. The logistic regression model was used to calculate the EC50 and EC95 values. Sevoflurane provided good conditions for both LMA insertion, and laryngoscopy and tracheal intubation without serious adverse effects. The EC50 and the EC95 of sevoflurane were 1.57 (SD 0.33)% and 2.22% for LMA insertion and 2.20 (SD 0.31)% and 2.62% for laryngoscopy and tracheal intubation. Thus, less sevoflurane is required for LMA insertion in children than for laryngoscopy and tracheal intubation.

A comparison of the hemodynamic effects of paracervical block and epidural anesthesia for labor analgesia

BACKGROUND

Both paracervical block (PCB) and epidural analgesia are sometimes associated with hemodynamic effects potentially harmful to the well-being of the fetus. Our study was designed to test the hypothesis that PCB would have a more profound effect on maternal and fetal blood flow than epidural analgesia.

METHODS

Forty-four healthy primiparous parturients were randomized to receive either PCB (n=21) or epidural analgesia (n= 23) with 25 or 30 mg of bupivacaine, respectively, for labor analgesia. Maternal blood pressure and fetal heart rate were recorded. Blood flow was measured using a color Doppler device. The blood flow measurements consisted of assessment of the pulsatility indices (PI) of the right maternal femoral artery and the main branch of the uterine artery (placental side), the umbilical artery and the fetal middle cerebral artery. The measurements were performed before administration of analgesia and approximately 15-20 min later after the onset of analgesia.

RESULTS

Both methods provided in general good analgesia, but rescue medication was required more often after PCB. Epidural analgesia decreased maternal blood pressure more than PCB and the PI of maternal femoral artery decreased after onset of epidural analgesia, indicating epidural-induced vasodilation. The PI of the uterine artery increased after the onset of PCB, indicating vasoconstriction of this artery. No significant adverse effects or differences in the well-being of the newborn were observed, as indicated by similar Apgar scores and pH-status.

CONCLUSION

There were small differences in the effects of PCB and epidural analgesia on uteroplacental circulation as well as on maternal hemodynamics. PCB may have a vasoconstrictive effect on the uterine artery. This and the fact that the parturients required rescue analgesia more frequently after PCB than after epidural block speaks for the feasibility of the latter in obstetrics.

Nursing activities and outcomes of care in the assessment, management, and documentation of children's pain

This study describes how assessment and documentation of children's acute postoperative pain is managed by nurses in university hospitals in Finland. A survey was conducted of 303 nurses working in children's wards of university-affiliated hospitals, and at the same time a retrospective chart review of 50 consecutive cases of operation of acute appendicitis was carried out. Charts were analyzed by content analysis, and the results of the survey are reported with percentage distribution and nonparametric statistical calculations. The results indicate that nurses assess pain mainly by observing the child's behavior and changes in physiology. Pain measurement instruments are rarely used, and nurses do not recognize them. The documentation of pain care is unsystematic and does not support the continuity of care. There is a clear need for development of assessment and documentation practices in the studied hospitals. Future research should look at the postoperative care of pain at home as well as care in non-university-affiliated hospitals.

Management of the paediatric patient

Recent introduction of new fast-onset short-duration anaesthetic drugs and the use of regional anaesthesia techniques in children have resulted in good control of anaesthesia and perioperative pain with few adverse effects. Ambulatory surgery has gained popularity in paediatric practice, particularly as children are often otherwise healthy and usually undergo minor surgery.

Difficult airway in a patient with Marshall-Smith syndrome

Marshall-Smith syndrome is a rare clinical disorder characterized by accelerated bone maturation, dysmorphic facial features, airway abnormalities and death in early infancy because of respiratory complications. Although patients with Marshall-Smith syndrome have several features with potential anaesthetic problems, previous reports about anaesthetic management of these patients do not exist. We present a case, in which severe hypoxia developed rapidly after routine anaesthesia induction in an eight-month-old male infant with this syndrome. After several unsuccessful attempts the airway was finally secured by blind oral intubation. After 2 weeks, laryngeal anatomy was examined with fibreoptic laryngoscopy which revealed significant laryngomalacia. Laryngoscopy was performed without problems with ketamine anaesthesia and spontaneous breathing. The possibility of a compromised airway should always be borne in mind when anaesthetizing patients with Marshall-Smith syndrome. Anaesthesia maintaining spontaneous breathing is safest for children with this syndrome. If tracheal intubation or muscle relaxation is required, precautions are needed to maintain a patent airway. Muscle relaxants should possibly be avoided before intubation.