Global Variations in Water Vapor and Saturation State Throughout the Mars Year 34 Dusty Season.

To understand the evolving martian water cycle, a global perspective of the combined vertical and horizontal distribution of water is needed in relation to supersaturation and water loss and how it varies spatially and temporally. The global vertical water vapor distribution is investigated through an analysis that unifies water, temperature and dust retrievals from several instruments on multiple spacecraft throughout Mars Year (MY) 34 with a global circulation model. During the dusty season of MY 34, northern polar latitudes are largely absent of water vapor below 20 km with variations above this altitude due to transport from mid-latitudes during a global dust storm, the downwelling branch of circulation during perihelion season and the intense MY 34 southern summer regional dust storm. Evidence is found of supersaturated water vapor breaking into the northern winter polar vortex. Supersaturation above around 60 km is found for most of the time period, with lower altitudes showing more diurnal variation in the saturation state of the atmosphere. Discrete layers of supersaturated water are found across all latitudes. The global dust storm and southern summer regional dust storm forced water vapor at all latitudes in a supersaturated state to 60-90 km where it is more likely to escape from the atmosphere. The reanalysis data set provides a constrained global perspective of the water cycle in which to investigate the horizontal and vertical transport of water throughout the atmosphere, of critical importance to understand how water is exchanged between different reservoirs and escapes the atmosphere.

Electroconvulsive therapy as a treatment for protracted refractory delirium in the intensive care unit--five cases and a review.

PURPOSE: Delirium in the intensive care unit (ICU) is conventionally treated pharmacologically but can progress into a protracted state refractory to medical treatment--a potentially life-threatening condition in itself. METHODS: We treated 5 cases of severe protracted delirium in our ICU with electroconvulsive therapy (ECT) after failure of conventional medical therapy. RESULTS: The delirious state of long standing agitation, anxiety, and discomfort was controlled in all patients. Electroconvulsive therapy was effective in controlling delirium in 4 patients. The last patient became calm, relieved of stress, and able to cooperate with the ventilator but remained in a state of posttraumatic amnesia after a head trauma. CONCLUSION: Although controversial, ECT is nevertheless recognized as an efficient and safe treatment for various psychiatric illnesses including delirium. Considering the significantly increased mortality and severe cognitive decline associated with delirium in the ICU, we find ECT to be a valuable treatment option for this vulnerable patient population. It can be considered when agitation cannot be controlled with medical treatment, when agitation and delirium make weaning impossible, or prolonged deep sedation the only alternative.

Propofol-remifentanil or sevoflurane for children undergoing magnetic resonance imaging? A randomised study.

BACKGROUND: Magnetic resonance imaging (MRI) of children is generally performed under sedation or with general anaesthesia (GA), but the ideal regimen has not been found. The aim of this study was to see if propofol-remifentanil would be a suitable alternative for the maintenance of anaesthesia in this category of patients. PATIENTS AND METHODS: Children aged 1-10 years, American Society of Anesthesiologists physical status 1-2 were included. After induction with thiopental or sevoflurane, the children were randomised to maintenance of anaesthesia with an infusion of propofol and remifentanil (group PR) (56 µg/kg/min of propofol and 0.06 µg/kg/min of remifentanil) or with sevoflurane 1.3 MAC (group S). A binasal catheter was placed in group PR and a laryngeal mask airway in group S. The children breathed spontaneously. The Paediatric Anaesthesia Emergence Delirium (PAED) score (primary end point), the number of movements during MRI, and the length of stay in the recovery room (secondary endpoints) were recorded. RESULTS: Sixty children were included in each group. A lower level of emergence delirium (measured as a lower PAED score) was found in group PR compared with group S, and the children in group PR were discharged earlier from the recovery room than the children in group S. However, 15 children in group PR vs. 0 in group S moved during the scan (P < 0.001). CONCLUSION: The PR infusion ensured a satisfactory stay in the recovery room, but additional boluses were necessary during the MRI. Sevoflurane was reliable during the MRI, but emergence delirium was a concern.

The duration of fibre-optic intubation is increased by cricoid pressure. A randomised double-blind study.

BACKGROUND: In some categories of patients, a rapid sequence induction using a fibre-optic method may be indicated. The aim of the present study was to examine the effect of cricoid pressure (CP) on the duration of fibre-optic intubation. The hypothesis was that CP would prolong the intubation time. METHODS: The study was a randomised, double-blind, cross-over study. The patients were intubated twice, in a randomised way, using a flexible fibrescope once with and once without CP. The intubation time and the visualisation of the glottis were registered. If the intubation was not completed within 180 s, it was registered as failed. CP was standardised to a pressure of 30 N. The data are given as the mean (standard deviation) or median [interquartile] (range). RESULTS: Fifty patients were included, with a mean age of 53 years (14.6) and mean body mass index of 26.4 (4.3). Three intubations without and 13 intubations with CP failed. The durations of intubation without and with CP were 59 s [53-79 s] (34-144 s) and 75 s [67-104 s] (43-179 s), respectively (P < 0.001). CONCLUSION: The study showed that CP prolongs the duration of fibre-optic intubation in patients with Mallampati grades 1-2.

Problems in obtaining sufficient anaesthesia with propofol and remifentanil: three cases, a test infusion, and a review.

BACKGROUND: Over a 5 yr period, we have encountered three patients in whom remifentanil appeared to have no clinical effect during general anaesthesia (GA). We describe seven anaesthetics in these three patients. METHODS: We reviewed the literature on this subject. A simple reproducible test to explore this response was designed. This involved a controlled infusion of increasing doses of remifentanil while observing respiratory variables, pain threshold, pupil size, and Glasgow coma scale score. In addition, blood was sampled for genotyping. RESULTS: No description of this impaired response was found in the review of the literature. Two of the patients agreed to participate in the test. In both patients, we found a seemingly normal analgesic response but a lack of respiratory depression and almost no depression of consciousness, even at doses well above the recommended level for clinical use. The genotyping did not explain the results of the test. CONCLUSIONS: The potential causes of this effect are discussed. We advise clinicians to be aware of this unusual response to remifentanil. If such a response is suspected, we recommend the use of another opioid. If this is suspected before GA, we propose the use of our test as a diagnostic tool.

Intubation of the morbidly obese patient: GlideScope(®) vs. Fastrach™.

BACKGROUND: Several potential problems can arise from airway management in morbidly obese patients, including difficult mask ventilation and difficult intubation. We hypothesised that endotracheal intubation of morbidly obese patients would be more rapid using the GlideScope(®) (GS) (Verathon Inc Corporate Headquarters, Bothell, WA, USA) than with the Fastrach™ (FT) (The Laryngeal Mask Company Ltd, Le Rocher, Victoria, Mahe, Seychelles). METHODS: One hundred patients who were scheduled for bariatric surgery were randomised to tracheal intubation using either a GS or an FT. The inclusion criteria were age 18-60 years and a body mass index of ≥ 35 kg/m(2) . The primary end point was intubation time, and if intubation was not achieved after two attempts, the other method was used for the third attempt. RESULTS: The mean intubation time was 49 s using the GS and 61 s using the FT (P = 0.86). A total of 92% and 84% of the patients were intubated on the first attempt using the GS and the FT, respectively. One tracheal intubation failed on the second attempt when the GS was used, and five failed on the second attempt when the FT was used. There were no incidents of desaturation and no differences between the groups in terms of mucosal damage or intubation difficulty. We experienced one oesophageal intubation using GS and six oesophageal intubations in five patients using FT. There was no difference between the pain scores or incidence of post-operative hoarseness associated with the two intubation techniques. CONCLUSION: No significant difference between the two methods was found. The GS and the FT may therefore be considered to be equally good when intubating morbidly obese patients.

Wound infiltration with local anesthetics for post-operative pain relief in lumbar spine surgery: a systematic review.

BACKGROUND: In this systematic review, we evaluated double-blind, randomized and controlled trials on the effect of wound infiltration with local anesthetics compared with the effect of placebo on post-operative pain after lumbar spine surgery. METHODS: Medline, the Cochrane Library and Google Scholar were searched for appropriate trials. Qualitative analysis of post-operative effectiveness was evaluated by assessment of significant difference (P < 0.05) between study groups regarding pain relief using pain scores, supplemental analgesic consumption and time to first analgesic request as outcome measures. Data on adverse effects were extracted and evaluated. RESULTS: Nine trials including 12 comparisons and 529 patients met the inclusion criteria. Ten comparisons presented data on pain scores. In only three of these 10 comparisons (30%), a reduction in pain score using local anesthetic infiltration was observed averaging between 8 and 40 mm on a 100 mm visual analog scale. In six out of 12 comparisons, the local anesthetic infiltration significantly reduced the supplemental opioid consumption after surgery. Observed reductions in analgesic consumption over the first 24 h averaged between 2.5 mg and approximately 15 mg of morphine. Data on opioid-related adverse effects were incomplete and difficult to interpret. CONCLUSION: Interpretation of the results was difficult because of diversity of the studies. However, clinical significance was in general questionable, with only a few trials showing a small or a modest reduction in pain intensity, which was observed mainly immediately after the operation. Similarly, although more frequently observed, only a minor and probably not clinically relevant reduction in opioid consumption was shown.

GlideScope videolaryngoscope vs. Macintosh direct laryngoscope for intubation of morbidly obese patients: a randomized trial.

BACKGROUND: Morbidly obese patients are at increased risk of hypoxemia during tracheal intubation because of increased frequency of difficult and impossible intubation and a decreased apnea tolerance. In this study, intubation with the GlideScope videolaryngoscope (GS) was compared with the Macintosh direct laryngoscope (DL) in a group of morbidly obese patients. METHODS: One hundred consecutive patients (body mass index ≥ 35 kg/m(2) ) scheduled for bariatric surgery were randomized 1 : 1 to intubation with GS (group GS) or DL (group DL). The primary outcome was intubation time. Secondary outcomes were number of attempts, Cormack-Lehane grade, intubation difficulty scale score (IDS), subjective difficulty of intubation, desaturation, airway bleeding, postoperative sore throat, and hoarseness. Group assignment was not blinded. RESULTS: Intubation in group GS and group DL lasted 48 (22-148) and 32 s (17-209), respectively (median (range); P = 0.0001); median difference 11 s (95% confidence interval 6-17). Laryngoscopic views were better in group GS with Cormack-Lehane grades 1/2/3/4 distributed as 35/13/2/0 vs. 23/13/10/4 in group DL (P = 0.003). IDS scores were significantly lower with GS than with DL. No other statistically significant differences were found. Two cases of failed intubation occurred in group DL vs. none in group GS (non-significant). Both patients were intubated with the GlideScope without problems. CONCLUSION: Intubation of morbidly obese patients with GS was slightly slower than with DL. The increased intubation time was of no clinical consequence as no patients became hypoxemic. Both devices generally performed well in the studied population, but the GS provided better laryngoscopic views and decreased IDS scores.

Evaluation of a transportable capnometer for monitoring end-tidal carbon dioxide.

We compared a small and transportable Capnometer (EMMA™) with a reference capnometer, the Siesta i TS Anaesthesia. During air-breathing through a facemask, both the EMMA (nine modules) and reference capnometer sampled expired gas simultaneously. A wide range of end-tidal carbon dioxide values were obtained during inhalation of carbon dioxide and voluntary hyperventilation. The median IQR [range] difference between all sets of carbon dioxide values (EMMA - reference) was -0.3 (-0.6 to 0.0 [-1.7 to 1.6] kPa; n = 297) using new batteries, which was statistically significant (p = 0.04) and located to two of the nine EMMAs tested. Using batteries with reduced voltage did not influence the measurements. The 95% CI of the medians of the differences were -0.4 to -0.2. We conclude that the EMMA can slightly under-read the end-tidal carbon dioxide but is generally comparable with a free-standing monitor. The precision of the EMMAs was similar whether new batteries or batteries with reduced voltage were used.

Sumatriptan does not affect arteriovenous oxygen differences in jugular and cubital veins in normal human subjects.

Arteriovenous anastomoses (AVAs) may open up during migraine attacks. In studies with anaesthetized and bilaterally vagosympatectomized pigs, triptans reduce AVA blood flow and increase the arteriovenous O2 difference (AVDO2). To investigate whether subcutaneous sumatriptan 6 mg could induce changes in the AVDO2, we measured the AVDO2 in the external jugular vein in healthy subjects. We also measured the AVDO2 in the internal jugular and cubital veins. There were no changes in AVDO2 after subcutaneous sumatriptan, probably because AVA blood flow is limited in humans with an intact sympathetic nervous system.

The asleep-awake technique using propofol-remifentanil anaesthesia for awake craniotomy for cerebral tumours.

BACKGROUND AND OBJECTIVE: We retrospectively reviewed the first 25 planned cases of awake craniotomies using the 'asleep-awake' technique, an alternative to the often-used 'asleep-awake-asleep' technique. METHODS: The patients were anaesthetized using propofol/remifentanil anaesthesia, a laryngeal mask and controlled ventilation according to a protocol defined before the start of this series of patients. The patients were awakened before the brain mapping and were kept awake throughout the rest of the procedure allowing for additional mapping and modification of the resection of the tumour if symptoms should develop. A small dose of remifentanil was infused during this period if necessary. RESULTS: Twenty-three patients were mapped as planned. One patient was not awakened due to protrusion of the brain during the awakening phase. Another patient was intubated preoperatively as it was impossible to obtain a tight laryngeal mask. All of the 23 patients were awake as from when the mapping session began and throughout the rest of the operation. In five cases the resection of the tumour was modified as symptoms emerged. These symptoms all subsided in due course. No case of hypoxia was recorded. In no case the respiratory rate was below 10 breaths min-1 in the awake period. Complications were comparable to other studies. The patients in the present study were all satisfied with the method. CONCLUSIONS: Different methods of anaesthesia have been described, but no method has been shown to be superior. The presented method seems to be a rational and useful technique allowing for modification of tumour resection, if symptoms should develop. The method was well tolerated by the patients.

Scrutinizing incident reporting in anaesthesia: why is an incident perceived as critical?

BACKGROUND: The purpose of the present study was to measure the incidence and type of incidents that occurred in relation to anaesthesia and surgery during a 1-year period in six Danish hospitals. Furthermore, we wanted to identify risk factors for incidents, as well as risk factors for incidents being deemed critical. METHODS: A four-page questionnaire describing patient data, type of anaesthesia and surgery, and occurrence of incidents was filled in for all anaesthesias in the period, and subsequently processed. The incident reporting form incorporated 59 predefined adverse events. The occurrence of one or more of these events described the incident. When the reporting anaesthetist deemed that an incident had harmed the patient, that incident was defined as critical. RESULTS: A total of 64,312 anaesthesias were reported, and in 7754 of them one or more incidents occurred. A total of 8510 incidents occurred, 4077 of them were solely related to the anaesthetic procedure, 3702 described events related to physiological alterations in the patient (physiological incidents). Three hundred and twenty-three of the incidents were deemed critical. High ASA score, high age, abdominal surgery, urgent surgery, and complex anaesthetic procedure were significant risk factors for physiological incidents and critical incidents. We could not identify a simple subset of adverse events that could adequately be used to describe the critical incidents. However, complex incidents, i.e. incidents involving more than one adverse event, were more likely to be deemed critical than simple incidents. CONCLUSION: The incidence of incidents was 12.1%, and the incidence of critical incidents was 0.5%. Incidents were more likely to be deemed critical in patients with an ASA score of III and above undergoing urgent surgery.

Effect of alfentanil on intracranial pressure during propofol-fentanyl anesthesia for craniotomy. A randomized prospective dose-response study.

BACKGROUND: The effect of alfentanil on intracranial pressure (ICP) in patients with supratentorial cerebral tumors has only been sparsely examined and with somewhat contradictory results. METHODS: Thirty-one patients were anesthetized with propofol and fentanyl. After removal of the bone flap a bolus-dose of alfentanil 10 (group 1), 20 (group 2), or 30 microg kg(-1) (group 3) was administered followed by an infusion of 10, 20, or 30 microg.kg(-1).h(-1) to patients in groups 1, 2, and 3, respectively. A control group received no alfentanil. Subdural ICP, mean arterial blood pressure (MAP), and cerebral perfusion pressure (CPP) were monitored and arterial and jugular bulb blood were sampled before and every minute for 5 min after the bolus administration of alfentanil and again after 5 min of hyperventilation to be able to calculate cerebral arterio-venous oxygen content difference (AVDO2) and carbon dioxide reactivity (CO2-reactivity). RESULTS: No changes in subdural ICP or AVDO2 from alfentanil in the study period were observed within the groups. However, alfentanil decreased MAP and CPP. The maximum CPP decrease (mean value of each group) was 4 mmHg, 8 mmHg, and 18 mmHg in groups 1, 2, and 3, respectively. There was no difference between groups as regards the CO2-reactivity. CONCLUSION: We conclude that administration of alfentanil to propofol-fentanyl anesthetized patients with supratentorial cerebral tumors decreases MAP and CPP in a dose-related way, but does not influence subdural ICP, AVDO2 or the CO2-reactivity.

Improved application of Lidocaine/Prilocaine cream in children. A randomized and prospectively controlled study of two application regimes.

UNLABELLED: Intravenous cannulation in children aged 6-12 years is less painful after a 90-min application of a Lidocaine/ Prilocaine cream followed by a 30-min interval without cream, than cannulation immediately after a 60-min application. BACKGROUND: Sixty-min application of an eutectic mixture of 25 mg g(-1) Lidocaine and 25 mg g(-1) Prilocaine cream is widely used in both adults and children to alleviate pain related to intravenous cannulation. However, studies have shown that this is not the optimal procedure in adults. Inspired by the results from these studies, the aim of the present study was to find an improved application regime for children. METHODS: In this prospective, randomized, and single-blind study 60 Caucasian children, aged 6-12 years, presenting for an i.v. cannulation were included. The children were allocated to either a 60-min application of anaesthetic cream followed by i.v. cannulation (Group A) or to a 90-min application followed by an interval of 30 min before cannulation (Group B). No sedatives or analgesics were given. The children scored their pain by a faces scale with four faces. RESULTS: The i.v. cannulations in Group B were less painful than the cannulations in Group A (Mann-Whitney test, P = 0.01). There was no difference between the two groups as regards problems when performing the cannulations. CONCLUSION: i.v. cannulation after application of anaesthetic cream for 90 min followed by a 30-min interval is less painful than the widely used 60-min application directly followed by cannulation.

Command-related distribution of regional cerebral blood flow during attempted handgrip.

To localize a central nervous feed-forward mechanism involved in cardiovascular regulation during exercise, brain activation patterns were measured in eight subjects by employing positron emission tomography and oxygen-15-labeled water. Scans were performed at rest and during rhythmic handgrip before and after axillary blockade with bupivacaine. After the blockade, handgrip strength was reduced to 25% (range 0-50%) of control values, whereas handgrip-induced heart rate and blood pressure increases were unaffected (13 +/- 3 beats/min and 12 +/- 5 mmHg, respectively; means +/- SE). Before regional anesthesia, handgrip caused increased activation in the contralateral sensory motor area, the supplementary motor area, and the ipsilateral cerebellum. We found no evidence for changes in the activation pattern due to an interaction between handgrip and regional anesthesia. This was true for both the blocked and unblocked arm. It remains unclear whether the activated areas are responsible for the increase in cardiovascular variables, but neural feedback from the contracting muscles was not necessary for the activation in the mentioned areas during rhythmic handgrip.

Age dependency of resistance to cerebrospinal fluid outflow.

OBJECT: Resistance to cerebrospinal fluid (CSF) outflow (Rout)is an important parameter in assessing the need for CSF shunt placement in patients with hydrocephalus. The normal lower limit of Rout has been estimated on the basis of the clinical effect of shunt placement in patients with varying values of Rout and in young healthy volunteers. The lack of clinical effect from CSF shunts in some elderly patients, despite elevated Rout,suggests that the normal value of Rout increases with age and may be higher in elderly persons. The aim of the present study was to examine the relationship between Rout and age in patients without known CSF dynamic disturbances. METHOD: Fifty-two patients ranging from 20 to 88 years of age and with no known CSF dynamic disorders were examined. The Rout was measured using a lumbar computerized infusion test. The correlation between Rout and age was analyzed by performing linear regression. The Rout increased significantly with patient age. The Rout in a patient in the eighth decade will be approximately 5 mm Hg/ml/minute higher than in a young patient. CONCLUSIONS: The present study shows a small but critical increase in Rout with increased patient age. A notable residual variation was present and borderline values of Rout should be regarded and used with caution.

Haemolysis following rapid experimental red blood cell transfusion--an evaluation of two infusion pumps.

BACKGROUND: The vast majority of infusion pumps used for rapid transfusion of large amounts of blood have never been properly examined regarding their influence on the quality of the red blood cells (RBCs) infused. In this study, we evaluated the effect of two different infusion pumps on the degree of RBC destruction following rapid experimental blood transfusion. METHODS: Divided into 2 groups according to age, 30 u of SAGM RBCs were infused through an experimental transfusion model by either a manual roller pump (MRP) or a pressure infusor pump (PIP). Fresh (i.e stored for 8-11 d) RBCs, 20 u, and 10 u of older (i.e. stored for 25-33 d) RBCs were randomly allocated to infusion with either of the two pumps. The rate of infusion was as fast as possible with the MRP, and with the PIP adjusted with an external applied pressure of 300 mm Hg. RBC samples collected before and after infusion were analyzed for total haemoglobin, free haemoglobin, haematocrit, total free potassium, lactate dehydrogenase (LDH) and the percentage of haemolysis. The time spent for each transfusion was measured by a stop watch. RESULTS: Following infusion, a marginal increase (i.e. considerably below 0.8%) in the percentage of haemolysis and LDH content was seen with both pumps. This increase was only statistically significant when RBCs stored for 8-11 d were used (P = 0.002 for both parameters). Irrespective of the age of the RBCs, no differences between the two pumps could be detected. Compared to the PIP, infusion with the MRP could be accomplished significantly faster, i.e. median 5.9 ml/s (5.2-6.4 ml/s) versus 2.9 ml/s (2.5-3.2 ml/s), (P < 0.0001). CONCLUSIONS: Both the pumps used in this study are safe alternatives for rapid transfusion of RBCs; however, with MRP this can be accomplished approximately twice as fast as with the PIP.

Validation of transcranial near-infrared spectroscopy for evaluation of cerebral blood flow autoregulation.

The aim of the study was to evaluate a new noninvasive transcranial near-infrared spectroscopy (TNIRS) technique for determination of the lower limit of cerebral blood flow (CBF) autoregulation by comparing this technique with the standard cerebral arteriovenous oxygen saturation difference (AVDo2) method. In eight healthy volunteers, mean arterial blood pressure was increased by infusion of angiotensin and decreased by the combination of lower-body negative pressure and labetalol. For each 5-mm Hg change in mean arterial pressure, blood was sampled from the bulb of the internal jugular vein and a radial artery, and simultaneously, the oxygen saturation of hemoglobin in the brain was measured with an INVOS 3100 Cerebral Oximeter (Somanetics). The lower limit of autoregulation was then calculated by a computer using (a) AVDo2 and (b) the difference between arterial oxygen saturation and the saturation determined with the cerebral oximeter (ACDo2). The median lower limit of autoregulation determined by the two methods was 73 and 78.5 mm Hg, respectively (p > 0.05). A statistically significant correlation between relative CBF (percentage of baseline) determined with the two methods was found below the lower limit of autoregulation (1/AVDo2 = 12 + 0.8 x 1/ACDo2; r = 0.55; p < 0.001). For all the 98 pairs of saturations registered, the correlation was 0.37 (p < 0.001), the mean difference was 16%, and the limits of agreement were -2.2 and 33.8%. We conclude that the cerebral oximeter might be useful in evaluation of the lower limit of cerebral autoregulation. This method, however, is of no value for estimation of levels of global cerebral oxygen saturation.