Near-infrared spectroscopy to measure brain oxygenation: A comparison of measurements on the skin, skull and dura mater.

BACKGROUND: The reliability of near-infrared spectroscopy (NIRS) for measuring cerebral oxygenation (ScO2 ) is controversial due to the possible contamination from extracranial tissues. We compared ScO2 measured with the NIRS optode on the forehead, the skull and the dura mater in anaesthetised patients undergoing craniotomy. We hypothesised that ScO2 measured directly on the skull and the dura mater would differ from ScO2 measured on the skin. METHODS: This prospective observational study included 17 adult patients scheduled for elective craniotomy. After induction of general anaesthesia, ScO2 was measured on the forehead skin, as well as on the skull and on the dura mater in the surgical field. The primary comparison was the difference in ScO2 measured on the dura mater and on ScO2 measured on the skin; secondary comparisons were the differences in ScO2 on the skull and ScO2 on the skin and the dura mater, respectively. Data were described with median (5%-95% range) and analysed with the Wilcoxon signed-rank test. RESULTS: ScO2 values on the dura mater were obtained in 11 patients, and median ScO2 (48%, 29%-95%) did not differ significantly from ScO2 on the skin (73%, 49%-92%; p = .052), median difference -25% (-35.6% to -1.2%). ScO2 on the skull (N = 16) was lower than that on the skin (63% [43%-79%] vs. 75% [61%-94%]; p = .0002), median difference -10% (-20.8 to -3.0). CONCLUSION: In adults undergoing craniotomy, NIRS-based ScO2 measured on the dura mater did not reach statistically significantly lower values than ScO2 measured on the skin, whereas values on the skull were lower than on the skin, indicating a contribution from scalp tissue to the signal.

Impact of hyperoxia and phenylephrine on cerebral oxygenation: An experimental clinical study.

BACKGROUND: Oxygen supply to the brain is of special importance during intracranial surgery because it may be compromised by intracranial pathology. A high arterial blood pressure (mean arterial pressure above 80 mmHg) and a high arterial oxygen tension (PaO2 above 12 kPa) is therefore often targeted in these patients, when for example intracranial pressure is increased or when a mass effect on brain tissue from a tumour is present, and it is pursued by administering vasopressors such as phenylephrine and by increasing inspiratory oxygen fraction (FiO2 ). However, whether these interventions increase cerebral oxygenation remains uncertain. We aimed to investigate the effect of hyperoxia and phenylephrine on brain tissue oxygen tension (PbtO2 ) in patients undergoing craniotomy. METHODS: In this experimental study, we included 17 adult patients scheduled for elective craniotomy. After securing a stable baseline of the oxygen probe, PbtO2 was measured in white matter peripherally in the surgical field during general anaesthesia. Primary comparisons were PbtO2 before versus after an increase in FiO2 from 0.30 to 0.80 as well as before versus after a bolus dose of phenylephrine (0.1-0.2 mg depending on patient haemodynamics). Data were analysed with the Wilcoxon signed rank test. RESULTS: We obtained complete data sets in 11 patients undergoing the FiO2 increase and six patients receiving the phenylephrine bolus. PbtO2 was 22 (median; 5%-95% range, 4.6-54) mmHg during 30% oxygen, 68 (8.4-99) mmHg during 80% oxygen (p = .004 compared to 30% oxygen), 21 (4.5-81) mmHg before phenylephrine, and 19 (4.2-56) mmHg after phenylephrine (p = .56 compared to before phenylephrine). CONCLUSION: In patients undergoing craniotomy under general anaesthesia, brain tissue oxygen tension increased with a high inspiratory oxygen fraction but remained unchanged after a bolus dose of phenylephrine.

Hyperlactatemia associated with elective tumor craniotomy: Protocol for an observational study of pathophysiology and clinical implications.

Hyperlactatemia occurs frequently after brain tumor surgery. Existing studies are scarce and predominantly retrospective, reporting inconsistent associations to new neurological deficits and prolonged hospital stay. Here we describe a protocol for a prospective observational study of hyperlactatemia during and after elective tumor craniotomy and the association with postoperative outcome, as well as selected pathophysiological aspects, and possible risk factors. We will include 450 brain tumor patients scheduled for elective craniotomy. Arterial blood samples for lactate and glucose measurement will be withdrawn hourly during surgery and until six hours postoperatively. To further explore the association of hyperlactatemia with perioperative insulin resistance, additional blood sampling measuring markers of insulin resistance will be done in 100 patients. Furthermore, in a subgroup of 20 patients, blood from a jugular bulb catheter will be drawn simultaneously with blood from the radial artery to measure the arterial to jugular venous concentration difference of lactate, in order to study the direction of cerebrovascular lactate flux. Functional clinical outcome will be determined by the modified Rankin Scale, length of stay and mortality at 30 days, 6 months, 1 year and 5 years. Clinical outcome will be compared between patients with and without hyperlactatemia. Multivariate logistic regression will be used to identify risk factors for hyperlactatemia. A statistical analysis plan will be publicized to support transparency and reproducibility. Results will be published in a peer-reviewed journal and presented at international conferences.

Temperature change in children undergoing magnetic resonance imaging-An observational cohort study.

AIM: An increasing number of children undergo magnetic resonance imaging requiring anesthesia or sedation to ensure their immobility; however, magnetic resonance imaging may increase body temperature whereas sedation or anesthesia may decrease it. We investigated changes in body temperature in children who underwent sedation or anesthesia for magnetic resonance imaging. METHODS: Children aged 12 weeks-12 years undergoing anesthesia and magnetic resonance imaging were included in this prospective observational study. Tympanic body temperature was measured before and after magnetic resonance imaging, and the difference between measurements was calculated. Associations between the temperature difference and patient- or procedure-related factors were evaluated with linear and logistic regression analysis. RESULTS: A total of 74 children were included, of whom 5 (7%) had a temperature increase ≥0.5°C. Mean temperature difference was -0.24°C (SD 0.48) for the entire group and -0.28°C for the youngest children (0-2 years). The temperature difference correlated positively with the duration of imaging (unadjusted coefficient 0.26, 95% confidence interval (CI), (0.01; 0.52)). CONCLUSION: In this study of sedated or anesthetized children undergoing magnetic resonance imaging, clinically relevant increases in body temperature above 0.5°C were only found in a few patients. However, longer imaging duration tended to be associated with increased body temperature.

Subarachnoid haemorrhage in a patient with undiagnosed aortic coarctation.

A man in his mid-30s was admitted with a thunderclap headache. He was conscious and hypertensive. A decade earlier, severe hypertension had been diagnosed and extensively investigated without revealing an underlying cause. Brain imaging showed subarachnoid haemorrhage caused by a ruptured pericallosal aneurysm. Endovascular occlusion was attempted, but as the sheath could not pass the aortic arch, it was converted to surgical aneurismal clipping. Intraoperative blood pressure measurement revealed a peak-to-peak gradient of 100 mm Hg across the aortic arch and an ankle/brachial index of 0.46 (normal range 0.9-1.2). Aortic coarctation was suspected, and angiographic imaging and echocardiography confirmed the diagnosis. Subacute direct stenting was performed, which normalised the peak-to-peak gradient and ankle/brachial index. To minimise the risk of severe complications, early diagnosis of aortic coarctation is important and can be facilitated by ankle/brachial index and echocardiography in the suprasternal view.

Waking Up in Pain: a prospective unselected cohort study of pain in 3702 patients immediately after surgery in the Danish Realm.

BACKGROUND: Acute and persistent pain after surgery is well described. However, no large-scale studies on immediate postoperative pain in the operating room (OR) exist, hindering potential areas of research to improve clinical outcomes. Thus, we aimed to describe the occurrence and severity of immediate postoperative pain in a large, unselected cohort. METHODS: This was a prospective cohort study, encompassing all procedures in 31 public hospitals in the Danish Realm, during a 5-day period including the weekend. Data on procedures and anesthesia were collected and the main outcome was occurrence of moderate or severe pain in the OR. Secondary outcomes included pain, sedation and nausea in the OR or during the first 15 min in the postanesthesia care unit (PACU) including relevant risk factors. Descriptive and logistic regression statistics were used. RESULTS: A total of 3675 procedures were included for analysis (87% inclusion rate). Moderate or severe pain occurred in 7.4% (95% CI 6.5% to 8.3%) of cases in the OR immediately after awakening, rising to 20.2% in the OR and/or PACU. Large intraprocedure and interprocedure variations occurred (0.0%-37.5%), and in 20% of cases with epidural-general anesthesia patients experienced moderate or severe pain. Independent risk factors were female sex, younger age, preoperative pain, daily opioid use and major surgical procedures. CONCLUSION: Moderate or severe pain in the immediate postoperative phase occurred in 20% of all cases with procedure and anesthesiological technique variations, suggesting a need for identification of relevant procedure-specific risk factors and development of preventive treatments. TRIAL REGISTRATION NUMBER: RoPR ID 43191.

"Cold-Steel" Phonosurgery of Reinke Edema Evaluated by the Multidimensional Voice Program.

OBJECTIVES: "Cold-steel" phonosurgery (PS) of Reinke edema is challenging, as the delicate structures of the vocal folds are difficult to preserve. This study aimed to evaluate the results of PS using the Multidimensional Voice Program (MDVP) . MATERIALS AND METHODS: From 2003 to 2007, 76 consecutive patients with Reinke edema were treated with PS for the first time. Reliable MDVP data were available in 37 female patients with both pre- and postoperative values in 14 patients. Voice quality and outcome after PS were evaluated by jitter, shimmer, soft phonation index, and fundamental frequency (f0) using MDVP, videostroboscopy, and a five-step voice outcome score. RESULTS: In the 14 patients, the mean f0 increased from 172 to 222 (P = 0.01), and jitter decreased from 2.03 to 1.17 (P = 0.04) 3 months postoperatively. Vocal fold grading based on videostroboscopy correlated significantly with jitter (P = 0.01). Patients with high preoperative values of jitter, shimmer, or soft phonation index had larger reductions than those with normal values. All had a postoperative reduction of the edemas. The mean voice outcome score increased postoperatively. None of the 37 patients reported complications, but seven patients were reoperated. Preoperatively, 95% of the 37 patients were smokers and only 9 (24%) changed smoking habits. Pre- or postoperative voice therapy was used in 23 (62%) patients. CONCLUSIONS: f0 and jitter by MDVP adequately reflected the postoperative voice improvement and reduction of the edema. Removal of large amounts of edematous tissue, many years of vocal abuse, and unchanged smoking habits may prevent optimal results.

Normative Values and Interrelationship of MDVP Voice Analysis Parameters Before and After Endotracheal Intubation.

PURPOSE: The Multi-Dimensional Voice Program (MDVP) is used for assessment of voice quality. A simple procedure for MDVP recordings was used in a randomized clinical trial (RCT) on induced vocal fold trauma due to intubation. This secondary study compares the common MDVP parameters with other normative values for adults and investigates the correlation between these MDVP parameters in relation to the "standardized" trauma of endotracheal intubation. METHODS: Preoperative and postoperative assessments of vocal fold pathology with flexible videolaryngoscopy and voice analysis with MDVP using the best-of-three standardized recording were performed in 121 patients with normal voices included consecutively in the RCT. The procedures of anesthesia were standardized. RESULTS: The normative MDVP values of this study are consistently lower compared with most normative values presented in other studies. The preoperative to postoperative differences in jitter values (jitter and relative average perturbation) were closely correlated to the shimmer values for patients with postoperative vocal fold edemas. In the patients with edema, the preoperative to postoperative differences in jitter had a correlation coefficient of 0.95 (P < 0.0001) to the difference in shimmer, compared with a correlation coefficient of 0.39 (P < 0.0001) in the patients without edema. CONCLUSIONS: This study supports the use of the "Best-of-Three" procedures for precise and relevant MDVP parameter calculations. The MDVP parameters, with closely correlated changes in jitter and shimmer values, accurately reflect the induced vocal fold edema when using the preoperative to postoperative changes.

Effect of prehospital ultrasound on clinical outcomes of non-trauma patients--a systematic review.

BACKGROUND: Advances in technology have made prehospital ultrasound (US) examination available. Whether US in the prehospital setting can lead to improvement in clinical outcomes is yet unclear. OBJECTIVE: The aim of this systematic review was to assess whether prehospital US improves clinical outcomes for non-trauma patients. METHOD: We conducted a systematic review on non-trauma patients who had an US examination performed in the prehospital setting. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the ISI Web of Science and the references of the included studies for additional relevant studies. We then performed a risk of bias analysis and descriptive data analysis. RESULTS: We identified 1707 unique citations and included ten studies with a total of 1068 patients undergoing prehospital US examination. Included publications ranged from case series to non-randomized, descriptive studies, and all showed a high risk of bias. The large heterogeneity between the different studies made further statistical analysis impossible. CONCLUSION: There are currently no randomized, controlled studies on the use of US for non-trauma patients in the prehospital setting. The included studies were of large heterogeneity and all showed a high risk of bias. We were thus unable to assess the effect of prehospital US on clinical outcomes. However, consistent reports suggested that US may improve patient management with respect to diagnosis, treatment, and hospital referral.

Response to succinylcholine in patients carrying the K-variant of the butyrylcholinesterase gene.

BACKGROUND: Succinylcholine is usually metabolized quickly by the butyrylcholinesterase enzyme (BChE) but genetic variants of BChE may prolong the duration of action. The Kalow (K) variant is the most common mutation in the butyrylcholinesterase gene (BCHE), being present in 25% of Caucasians. The significance of the K-variant for the duration of action of succinylcholine has not been well studied. Our hypothesis was that the duration of action of succinylcholine would be prolonged in patients heterozygous for the K-variant genotype compared with the normal genotype (wild-type). METHODS: We included 70 adult surgical patients who received succinylcholine 1 mg/kg for rapid sequence induction. Neuromuscular monitoring was performed using ulnar nerve stimulation and acceleromyography. Duration of action of succinylcholine was defined as the time to 90% recovery of first twitch in train-of-four (T(1) 90%), BChE activity was determined, and the presence of BCHE K and A (atypical) variants were determined using DNA analysis. RESULTS: The wild-type BCHE was present in 38 patients, and 21 were heterozygous for the K-variant. Mean (SD) T(1) 90% in patients heterozygous for the K-variant, 11.6 (3.5) minutes, was longer than in patients with the wild-type genotype, 9.5 (2.7) minutes (P = 0.023), with a mean (95% confidence interval) difference of 2.1 (0.3-4.0) minutes. Patients heterozygous for the K-variant had a BChE activity of 5978 U/L compared with 7703 U/L in the wild-type group (P = 0.0045). CONCLUSION: We conclude that the mean duration of action of succinylcholine is prolonged for the patient heterozygous for the K-variant allele by at most 4 minutes relative to the wild-type, but this difference is small relative to the wide variability and overlap in recovery times among all patients.

[Information campaigns can reduce unnecessary prolonged time of thirst in elective surgical patients]. / Information kan reducere unødvendig tørstetid hos elektive kirurgiske patienter.

This prospective study was aimed at identifying the time of thirst above the recommended two hours after repeated information campaigns. Elective surgical patients ≥ 15 years of age were eligible to answer the questionnaire in four different periods between which information campaigns were carried out. A total of 765 patients were included. The median time of thirst was reduced from 6.5 hours to 3.0 hours (p < 0.0001) over a two-year period. Repeated interventions were found to be necessary to reduce the period of thirst to the recommended two hours for elective surgical patients.

Endotracheal intubation with airtraq® versus storz® videolaryngoscope in children younger than two years - a randomized pilot-study.

BACKGROUND: New laryngoscopes have become available for use in small children. The aim of the study was to compare the Storz® videolaryngoscope (SVL) to the Airtraq® Optical laryngoscope (AOL) for tracheal intubation in children younger than two years of age who had a normal airway assessment. Our hypothesis was that the SVL would have a better success rate than the AOL. METHODS: Ten children aged 2 years or younger scheduled for elective cleft lip/palate surgery were included. The anesthesia was standardized and a Cormack-Lehane (CL)-score was obtained using a Macintosh laryngoscope. After randomization CL-score and endotracheal tube positioning in front of the glottis was performed with one device, followed by the same procedure and intubation with the other device. The video-feed was recorded along with real-time audio. The primary endpoint was the success rate, defined as intubation in first attempt. Secondary endpoints were the time from start of laryngoscopy to CL-score, tube positioning in front of the glottis, and intubation. RESULTS: Two intubation attempts were needed in two of five patients randomized to the SVL. The difference in time (SVL vs. AOL) to CL-score was 4.5 sec (p = 0.0449). The difference in time (SVL vs. AOL) to tube positioning was 11.6 sec (p = 0.0015). Time to intubation was 29.0 sec for SVL and 15.8 sec for AOL. CONCLUSION: No difference in the success rate of endotracheal intubation could be established in this ten patient sample of children younger than two years with a normal airway assessment scheduled for elective cleft lip/palate surgery. However, the Airtraq® Optical videolaryngoscope showed a number of time related advantages over the Storz® videolaryngoscope. Because of the small sample size a larger trial is needed to confirm these findings. Both devices were considered safe in all intubations. TRIAL REGISTRATION: ClinicalTrials.gov; Identifier NCT01090726.

[Fatal course of a patient during in vitro fertilisation treatment]. / Fatalt forløb ved in vitro-fertilisation.

Chylomicronaemia syndrome is a rare disorder primarily caused by a genetic defect which increases triglycerides, combined with a secondary inducing factor. We describe the fatal course of a 33-year-old, pregnant woman with known dyslipidaemia who had been treated with in vitro fertilisation and developed chylomicronaemia syndrome with severe hypertriglyceridaemia, hypertriglyceridaemia-induced acute pancreatitis and septic shock. Appropriate treatment including close monitoring, severe restriction of dietary fat intake and early plasmapheresis is emphasized - especially during pregnancy.

Hemodynamic differences between propofol-remifentanil and sevoflurane anesthesia for repair of cleft lip and palate in infants.

BACKGROUND: Propofol-remifentanil anesthesia is widely used in adults but few studies are available in infants. We aimed at comparing the hemodynamic effects of propofol-remifentanil vs sevoflurane-fentanyl anesthesia. In addition, we sought to investigate recovery and whether remifentanil induced acute opioid tolerance. METHODS: In total, 39 infants 4-6 months old were prospectively enrolled and randomized to receive either a combination of remifentanil and propofol (n = 17) or a sevoflurane-fentanyl anesthesia (n = 22) for surgical repair of cleft lip and palate. In both groups, sevoflurane was used for induction of anesthesia and fentanyl was administered before tracheal extubation. Mean arterial blood pressure and heart rate were recorded every 5 min after induction. We also recorded time from termination of surgery to tracheal extubation, postoperative behavior and the need for analgesia for the first 24 h after surgery. Postoperative observations were blinded. RESULTS: In the remifentanil-propofol group, the mean arterial blood pressure was higher [58 (51-65) vs 51 (45-55), P = 0.02] and the mean heart rate was lower [111 (108-113) vs 128 (122-143), P < 0.0001]. There were no differences in recovery time or behavior after surgery. In the remifentanil group, a median fentanyl dose of 4 microg x kg(-1) was required to insure a smooth recovery, but there was no difference in morphine consumption during the first 24 h after surgery. CONCLUSIONS: A high-dose remifentanil-propofol infusion was associated with a higher blood pressure and lower heart rate than sevoflurane-fentanyl anesthesia in infants. Postoperative morphine consumption, recovery time and quality were similar.