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I. INTRODUCTION The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide measurements of the reflected short-wave (0.25-4.0 µm) and emitted long-wave (4.0-50 µm) top of the atmosphere (TOA) radiance over three along-track views (forward, nadir and backward). The instrument has three fixed telescopes, one for each view, each containing a broadband detector. The BBR instrument is led by SEA in the UK with RAL responsible for the BBR optics unit (OU) while EADS Astrium is the EarthCARE prime contractor. A detailed description of the instrument is provided in [1]. The BBR detectors consist in three dedicated assemblies under the responsibility of INO. The detectors development started in 2008 and led to the design and implementation of a new gold black deposition facility at INO [2], in parallel with the preliminary and detailed design phases of the detector assemblies. As of today, two breadboard models and one engineering model have been delivered to RAL. In the BBR OU each detector mechanically interfaces with the teles cope and electrically with the front-end electronics (FEE). The detectors’ development is now at the Critical Design Review (CDR) level. This paper first provides a description of the detector design along with its principles of operation. It further presents and discusses measurement and analysis results for the performance characterization of the engineering model in the context of the applicable requirements. Detector-level qualification planning is finally discussed. II. DETECTOR DESCRIPTION The detectors are required to provide fast pixel response time (< 6 ms), uniform spectral response over the entire spectral range (0.25-50 µm), and an NEP lower than 3.7 nW at 17 Hz (after time averaging over a period of 20 ms). The engineering model detector is shown in Fig. 1, with (right) and without (left) its cover. Each detector consists of an uncooled focal plane array (FPA) hybridized with a readout integrated circuit (ROIC). The FPA is based on INO’s VO

While natural gas pipelines already benefit from airborne, remote detection of leaks [1, 2], oil pipeline leak detection has been for a long time reliant on SCADA systems limited in their capability to detect very small leaks, and/or visual inspection of the right of way (line flyers, pipeline employees or members of the public). This paper presents a novel and complementary way of detecting small leaks (i.e. sensitivity of 0.1 L/minute, 1 barrel/day) of oil (crude or refined products) using an optical detection system mounted on an airborne platform (UAV, plane or helicopter). The scope of this paper is based on the requirements provided by TransCanada, namely sensitivity (herein referred as LOD — Limit of Detection) and accuracy (herein referred as spatial resolution) as similar to their description in API 1130, while the topic of reliability is addressed in our noted concerns on the false alarms that may be generated in Infrared-DiAL based systems due to soil reflectivity. Robustness, as described in API 1130, was out of scope. Keeping in mind the requirement of airborne operation, three different approaches for the detection of leaks along long pipeline ROWs were studied. Infrared Differential Absorption lidar (IR-DiAL), UltraViolet Raman lidar (UV-Raman lidar) and UltraViolet Laser-Induced Fluorescence lidar (UV-LIF lidar) have been tested in realistic conditions. In the first round of tests, laboratory spectral measurements of vapors in a closed cell were performed. In the second round of tests, the breadboards were placed in a mobile laboratory and the light beams aimed at a large open at 40 to 50 meters and reflected off a sand target. Finally, the mobile laboratory with the breadboards was installed at ∼40 meters from a leak simulator. The leak simulator was made by using a large sand container in which petroleum products were leaked. Intermediate scale leak simulator tests showed that it is clearly a challenge to correlate a measured concentration to an actual leak size. Tests have also shown that there is a strong concentration gradient in the air above a leak. This indicates that a better overall detection performance should be obtained with a measurement using the air next to the ground, and that it is feasible to detect a leak of less than 1 barrel/day. UV-Raman tests performed in the outdoors suggested a Limit Of Detection (LOD) of the system below 1 500 ppm-m when detecting all hydrocarbons. Because of the hardware that would be needed to lower this detection limit, results suggest abandoning the Raman technique for remote leak detection from an airborne platform. IR-DiAL showed the best sensitivity for the detection of hydrocarbons (< 1 ppm-m of LOD). However the effective LOD will be reduced because of the soil spectral reflectance variations that may lead to a high false alarm rate for concentrations of hydrocarbons lower than 235 ppm-m. The UV-absorption approach was also briefly tested, suggesting a LOD for benzene of between 1.5 and 2.5 ppm-m. The UV absorption of benzene is not affected by ground spectral reflectance variations. This is an approach that will be investigated further.

This paper presents a study of different approaches to the measurement of the above ground vapor plume created by the spill caused by a small 0.1 l/min (or less) leak in an underground liquid petroleum pipeline. The scenarios are those for the measurement from an airborne platform. The usual approach is that of IR absorption, but in the case of liquid petroleum products, there are drawbacks that will be discussed, especially when using alkanes to detect a leak. The optical measurements studied include UV enhanced Raman lidar, UV fluorescence lidar and IR absorption path integrated lidars. The breadboards used for testing the different approaches will be described along with the set-ups for leak simulation. Although IR absorption would intuitively be the most sensitive, it is shown that UV-Raman could be an alternative. When using the very broad alkane signature in the IR, the varying ground spectral reflectance are a problem. It is also determined that integrated path measurements are preferred, the UV enhanced Raman measurements showing that the vapor plume stays very close to the ground.

Background About one in four patients suffers from postoperative nausea and vomiting. Fortunately, risk scores have been developed to better manage this outcome in hospitalized patients, but there is currently no risk score for postdischarge nausea and vomiting (PDNV) in ambulatory surgical patients. Methods We conducted a prospective multicenter study of 2,170 adults undergoing general anesthesia at ambulatory surgery centers in the United States from 2007 to 2008. PDNV was assessed from discharge until the end of the second postoperative day. Logistic regression analysis was applied to a development dataset and the area under the receiver operating characteristic curve was calculated in a validation dataset. Results The overall incidence of PDNV was 37%. Logistic regression analysis of the development dataset (n=1,913) identified five independent predictors (odds ratio; 95% CI): female gender (1.54; 1.22 to 1.94), age less than 50 yr (2.17; 1.75 to 2.69), history of nausea and/or vomiting after previous anesthesia (1.50; 1.19 to 1.88), opioid administration in the postanesthesia care unit (1.93; 1.53 to 2.43), and nausea in the postanesthesia care unit (3.14; 2.44-4.04). In the validation dataset (n=257), zero, one, two, three, four, and five of these factors were associated with a PDNV incidence of 7%, 20%, 28%, 53%, 60%, and 89%, respectively, and an area under the receiver operating characteristic curve of 0.72 (0.69 to 0.73). Conclusions PDNV affects a substantial number of patients after ambulatory surgery. We developed and validated a simplified risk score to identify patients who would benefit from long-acting prophylactic antiemetics at discharge from the ambulatory care center.

Study Objective To evaluate the safety and efficacy of sugammadex for reversal of rocuronium-induced neuromuscular blockade in patients with pulmonary disease. Design Phase III, randomized, multicenter, parallel-group, comparative, safety-assessor blinded study. Setting Nine hospital sites. Patients 77 ASA physical status 2 and 3 patients, aged ≥ 18 years, with a history of pulmonary disease, and scheduled for surgery with general anesthesia requiring neuromuscular blockade. Interventions Following anesthesia induction, patients received rocuronium 0.6 mg/kg with 0.15 mg/kg maintenance doses as needed. Patients were randomized to receive sugammadex 2 mg/kg or 4 mg/kg after the last rocuronium dose at reappearance of the second twitch. Measurements Safety evaluations included adverse events, laboratory parameters, vital signs, and evidence of recurrent or residual neuromuscular blockade. Efficacy was evaluated as the time from sugammadex administration to recovery of the train-of-four (TOF) ratio to ≥ 0.9. Main Results Safety was comparable between doses, with no evidence of residual or recurrent neuromuscular blockade. Two bronchospasm cases were reported (4 mg/kg group), both in patients with asthma who received desflurane for anesthesia maintenance. Geometric mean (95% confidence interval) times to a TOF ratio of ≥ 0.9 were 2.1 (1.7 - 3.1) min (2 mg/kg) and 1.8 (1.5 - 2.7) min (4 mg/kg). Conclusion Sugammadex 2 mg/kg and 4 mg/kg were well tolerated and effective in patients with a history of pulmonary disease. Bronchospasm is a possibility when administering sugammadex to patients with underlying pulmonary disease.

Background Intraoperative transfusion decisions generally are guided by blood loss estimation and periodic invasive hemoglobin measurement. Continuous hemoglobin measurement by pulse cooximetry (pulse hemoglobin; Rainbow® SET Pulse CO-Oximeter, Masimo Corporation, Irvine, CA) has good agreement with laboratory hemoglobin in healthy volunteers and could aid transfusion decision-making. Because intraoperative physiology may alter performance of this device, this study investigated pulse hemoglobin during surgery. Methods Ninety-one adult patients undergoing abdominal or pelvic surgery in which large blood loss was likely were studied. Time-matched pulse hemoglobin measurements were recorded for each intraoperative arterial hemoglobin measurement obtained. Agreement between measurements was assessed by average difference (mean ± SD, g/dl), linear regression, and multiple measures Bland-Altman analysis. Results The average difference between 360 time-matched measurements (bias) was 0.50 ± 1.44 g/dl, with wider limits of agreement (-2.3 to 3.3 g/dl) than reported in healthy volunteers. The average difference between 269 paired sequential pulse and arterial hemoglobin changes was 0.10 ± 1.11 g/dl, with half between -0.6 and 0.7 g/dl of each other. The bias was larger in patients with blood loss of more than 1,000 ml; hemoglobin less than 9.0 g/dl; any intraoperative transfusion; or intraoperative decrease in arterial hemoglobin at the time of sampling ≥2 g/dl (all P < 0.001). The range of bias was narrower at deeper anesthesia (P < 0.001). Conclusions Evaluation of the sensor and software version tested suggests that although pulse cooximetry may perform well in ambulatory subjects, in patients undergoing surgery in which large blood loss is likely, an invasive measurement should be used in transfusion decision-making.

There are well documented methods for stack emissions monitoring. These are all based on stack sampling through sampling ports in well defined conditions. Once sampled, the molecules are quantified in instruments that often use optical techniques. Unfortunately sampling ports are not found on all stacks/ducts or the use of the sampling ports cannot be planned efficiently because of operational constraints or the emissions monitoring equipment cannot be driven to a remote stack/duct. Emissions monitoring using many of the same optical techniques, but at a standoff distance, through the atmosphere, using short range high spatial resolution lidar techniques was thus attempted. Standoff absorption and Raman will be discussed and results from a field campaign will be presented along with short descriptions of the apparatus. In the first phase of these tests, the molecules that were targeted were NO and O2 . Spatially resolved optical measurements allow for standoff identification and quantification of molecules, much like the standardized methods, except for the fact that it is not done in the stack, but in the plume formed by the emissions from the stack. The pros and cons will also be discussed, and in particular the problem of mass emission estimates that require the knowledge of the flow rate and the distribution of molecular concentration in the plane of measurement.

The development of a novel broadband and tunable optical parametric generator (OPG) is presented. The OPG properties are studied numerically and experimentally in order to optimize the generator’s use in a broadband spectroscopic LIDAR operating in the short and mid-infrared. This paper discusses trade-offs to be made on the properties of the pump, crystal, and seeding signal in order to optimize the pulse spectral density and divergence while enabling energy scaling. A seed with a large spectral bandwidth is shown to enhance the pulse-to-pulse stability and optimize the pulse spectral density. A numerical model shows excellent agreement with output power measurements; the model predicts that a pump having a large number of longitudinal modes improves conversion efficiency and pulse stability.

Recent advances in the INO broadband SWIR/MWIR spectroscopic lidar will be presented. The system is designed for the detection of gaseous pollutants via active infrared differential optical absorption spectroscopy (DOAS). Two distinctive features are a sub-nanosecond PPMgO:LN OPG capable of generating broadband (10 to

The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument is led by SEA in the UK with RAL responsible for the BBR optics unit (OU) while EADS Astrium is the EarthCARE prime contractor. The BBR detectors consist of three dedicated assemblies under the responsibility of INO. The detectors development started in 2008 and led to the design and implementation of a new gold black deposition facility at INO, in parallel with the preliminary and detailed design phases of the detector assemblies. As of today, two breadboard models and one engineering model have been delivered to RAL. The engineering qualification model manufacturing activities are on-going. This paper first provides an overview of the detectors assembly and principles of operation, with emphasis given to processes developed for the assembly and integration of the detectors. Detector-level qualification planning is finally discussed.

Total hemoglobin (tHb) is one the most frequently ordered laboratory measurements. Pulse CO-Oximetry™ (Masimo Corp., Irvine, CA) is a multi-wavelength spectrophotometric method for noninvasive and continuous hemoglobin monitoring (SpHb). In this study, we evaluated the accuracy of SpHb compared with laboratory CO-Oximeter measurement of tHb from arterial blood samples in 20 healthy volunteer subjects undergoing hemodilution.After enrollment, approximately 500 mL of blood was drawn from subjects through an arterial or venous catheter. Each subject then rapidly received crystalloid i.v. fluid to compensate for the decrease in intravascular volume and reduce the hemoglobin concentration. Subjects received a maximum of 30 mL/kg i.v. fluid. SpHb was continuously monitored and recorded, and serial arterial blood samples were taken during the procedure. SpHb accuracy was analyzed by pairing SpHb and tHb measurements after the arterial blood draw with the resulting tHb test result. Bias, precision, and the average root-mean-square error were calculated.One hundred sixty-five tHb measurements were collected. The average decrease in tHb during the blood removal and hemodilution procedure was 2.4 ± 0.8 g/dL (mean ± SD). The average difference between 335 paired measurements of SpHb and tHb was -0.15 g/dL, 1 SD of the difference was 0.92 g/dL, and the average root-mean-square difference was 0.94 g/dL. The difference between SpHb and tHb was2.0 g/dL for 97% of the measurements. The difference was1.5 g/dL for 97% of the measurements when tHb was10 g/dL.Pulse CO-Oximetry-based SpHb measurement is accurate within 1.0 g/dL (1 SD) compared with laboratory CO-Oximeter tHb measurement in subjects undergoing hemodilution.

The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide top-of-atmosphere (TOA) radiance measurements in two spectral channels, and over three along-track directions. The instrument has three fixed telescopes (one for each view) each containing a broadband detector. Each detector consists of an uncooled 30-pixel linear focal plane array (FPA) coated with gold black in order to ensure uniform spectral responsivity from 0.2 μm to 50 μm. The FPA is hybridized with a readout integrated circuit (ROIC) and a proximity electronics circuit-card assembly (CCA) packaged in an aluminum base plate with cover. This paper provides a technical description of the detector design and operation. Performance data at the FPA pixel level as well as unit-level test results on early prototypes of the detectors are also presented.

HMG-CoA reductase inhibitors (Statins) have been shown to reduce blood brain barrier (BBB) disruption and improve neurologic outcome in cerebrovascular disorders. Brain injury due to neurosurgical procedures can lead to post-operative complications such as brain edema and altered neurologic function. The objective of this study was to evaluate whether simvastatin reduces brain edema by preventing BBB disruption and improves neurologic status after surgically-induced brain injury (SBI).Animals were pretreated for seven days with vehicle or simvastatin i.p. daily, after which they underwent SBI. Neurologic evaluation was assessed at 24 hours post-SBI and the animals were sacrificed for brain water content calculation and BBB evaluation.Brain water content was significantly increased in the right frontal lobe in all SBI groups as compared to the left frontal lobe. There was no significant difference in brain water content in the right frontal lobe between simvastatin and vehicle treated groups. Evans blue testing did not show a significant difference in disruption of the BBB between groups. Neurologic scores were not significantly different.Simvastatin did not reduce brain water content, protect the BBB, or improve neurologic scores after SBI.

Hypertonic saline (HTS) has been proposed as a treatment after aneurysmal subarachnoid hemorrhage (SAH) to minimize ischemic brain injury due to its osmotic and rheologic properties. Although the benefits of 7.2% HTS use in brain injury have been studied, there is a paucity of data on the use of 3%HTS.We investigated whether 3%HTS can reduce brain water content and improve neurologic function after SAH in the rodent model compared to 0.9% saline solution (NS). Neurologic testing was conducted at 24 hours post-SAH prior to sacrificing animals for brain water content evaluation.There was significant potentiation of brain water content in the right hemisphere between 3%HTS and NS groups. The modified Garcia score was not significantly different between the two groups; however, the vibrissae-stimulated forelimb placement test showed significantly lower scores in the HTS group. 3%HTS does not decrease brain edema or improve neurologic deficits as compared to NS. In fact, our study showed 3%HTS potentiated brain edema and worsened neurologic deficits in the rat SAH model.Given the potential adverse effects of HTS therapies, including hyperchloremic acidosis, and the lack of benefit found in our study, more investigation is required to evaluate the clinical use of 3%HTS in the setting of SAH.

Intra-operative cerebral ischemia can be catastrophic, and volatile anesthetic agents have been recognized for their potential neuroprotective properties since the 1960s. In this review, we examine the neuroprotective effects of five volatile anesthetic agents in current or recent clinical use: isoflurane, sevoflurane, desflurane, halothane and enflurane.A review of publications in the National Library of Medicine and National Institutes of Health database from 1970 to 2007 was conducted.Volatile anesthetic agents have been shown to be neuroprotective in multiple animal works of ischemic brain injury. Short-term neuroprotection (1 week post-ischemia) in experimental cerebral ischemia has been reported in multiple works, although long-term neuroprotection (or = 1 week post-ischemia) remains controversial. Comparison works have not demonstrated superiority of one specific volatile agent over another in experimental models of brain injury. Relatively few human works have examined the protective effects of volatile anesthetic agents and conclusive evidence of a neuroprotective effect has yet to emerge from human works.Proposed mechanisms related to the neuroprotective effect of volatile anesthetic agents include activation of ATP-dependent potassium channels, up-regulation of nitric oxide synthase, reduction of excitotoxic stressors and cerebral metabolic rate, augmentation of peri-ischemic cerebral blood flow and up-regulation of antiapoptotic factors including MAP kinases.

BACKGROUND HMG-CoA reductase inhibitors (Statins) have been shown to reduce blood brain barrier (BBB) disruption and improve neurologic outcome in cerebrovascular disorders. Brain injury due to neurosurgical procedures can lead to post-operative complications such as brain edema and altered neurologic function. The objective of this study was to evaluate whether simvastatin reduces brain edema by preventing BBB disruption and improves neurologic status after surgically-induced brain injury (SBI). METHODS Animals were pretreated for seven days with vehicle or simvastatin i.p. daily, after which they underwent SBI. Neurologic evaluation was assessed at 24 hours post-SBI and the animals were sacrificed for brain water content calculation and BBB evaluation. FINDINGS Brain water content was significantly increased in the right frontal lobe in all SBI groups as compared to the left frontal lobe. There was no significant difference in brain water content in the right frontal lobe between simvastatin and vehicle treated groups. Evans blue testing did not show a significant difference in disruption of the BBB between groups. Neurologic scores were not significantly different. CONCLUSIONS Simvastatin did not reduce brain water content, protect the BBB, or improve neurologic scores after SBI.

BACKGROUND Hypertonic saline (HTS) has been proposed as a treatment after aneurysmal subarachnoid hemorrhage (SAH) to minimize ischemic brain injury due to its osmotic and rheologic properties. Although the benefits of 7.2% HTS use in brain injury have been studied, there is a paucity of data on the use of 3%HTS. METHODS We investigated whether 3%HTS can reduce brain water content and improve neurologic function after SAH in the rodent model compared to 0.9% saline solution (NS). Neurologic testing was conducted at 24 hours post-SAH prior to sacrificing animals for brain water content evaluation. FINDINGS There was significant potentiation of brain water content in the right hemisphere between 3%HTS and NS groups. The modified Garcia score was not significantly different between the two groups; however, the vibrissae-stimulated forelimb placement test showed significantly lower scores in the HTS group. 3%HTS does not decrease brain edema or improve neurologic deficits as compared to NS. In fact, our study showed 3%HTS potentiated brain edema and worsened neurologic deficits in the rat SAH model. CONCLUSIONS Given the potential adverse effects of HTS therapies, including hyperchloremic acidosis, and the lack of benefit found in our study, more investigation is required to evaluate the clinical use of 3%HTS in the setting of SAH.

This work presents the proof of concept of a remote sensing system designed for the detection of molecular species such as gas pollutants via active differential optical absorption spectroscopy in the short- and mid-wavelength infrared. The system includes an optical parametric generator generating broad linewidth pulses tunable between 1.5 and 3.8 μm. A telescope coupled to a grating spectrograph and an in-house gated HgCdTe avalanche photodiode measures the whole return spectrum from each pulse. Experiments show simultaneous detection in atmospheric air and inside a cell of H2O and CO2 at 2 μm, and H2O and CH4 at 3.3 μm. The detection limits for CO2 and CH4 are 158 and 1 ppm·m, respectively. A new algorithm is also presented enabling the determination of concentrations when spectra include strong absorption features.

In many sensing systems, a highly coherent laser source is necessary to perform sensitive interferometric or coherent measurements. At TeraXion, we have built a compact laser system that provides a stable laser frequency with a very narrow linewidth using a 60 mW DFB semiconductor laser. The linewidth reduction system uses a frequency discriminator to measure the laser frequency noise and provides an electrical feedback to reduce this noise over a given bandwidth. Experimental work shows that the phase noise of the DFB semiconductor laser can be reduced by more than 4 orders of magnitude from 10 Hz to 100 kHz. We analyzed the effect of the particular frequency noise spectrum of such a laser on its degree of coherence, its linewidth and the resulting interferometric noise. The laser linewidth computed from the power spectral density of frequency noise of the laser is reduced from 570 kHz down to an equivalent of 1.8 kHz when the output signal is observed for 30 ms, and from 370 kHz to 18 Hz for 1 ms. Similarly, the coherence length is increased from 145 m up to 45 km for fringes observed over 30 ms. Each result is compared with those obtained with a fiber laser.

This paper deals with improving coherence length of fiber and semiconductor lasers using a linewidth-reduction-system and absolute frequency-locking. Linewidths below kilohertz and relative frequency stability > 2×10-12 for 100s averaging time are obtained.

Objective: Transesophageal echocardiography is a diagnostic and monitoring modality. The objectives of our study were to compare the diagnoses obtained with continuous transesophageal echocardiography and hemodynamic monitoring in the intensive care unit, to determine interobserver variability of diagnosis obtained with both modalities, and to evaluate its impact. Design: Prospective cohort study. Setting: Surgical intensive care unit. Patients: Consecutive hemodynamically unstable patients after cardiac surgery. Interventions: At admission, unstable patients were monitored during 4 hrs with transesophageal echocardiography and standard hemodynamic monitoring. The critical care physician evaluated the patients based on all information except the transesophageal echocardiography at 0, 2, and 4 hrs and formulated a hypothesis on the most likely cause of hemodynamic instability. Transesophageal echocardiography information was provided after each evaluation. To evaluate interobserver variability, all the hemodynamic and echocardiographic information was gathered, randomized, and evaluated by five clinicians for the hemodynamic data and five echocardiographers for the transesophageal echocardiography data. The evaluators were blinded to all other information. Kappa statistics were used to evaluate agreement. Impact of transesophageal echocardiography was assessed retrospectively by using the Deutsch scale. Results: Twenty patients qualified for the study. The agreement between the hemodynamic and echocardiographic diagnosis showed a kappa at admission, 2 hrs, and 4 hrs of 0.33, 0.47, and 0.28. The interobserver agreement for the initial diagnosis (p = .014) and between all evaluators (p

UnlabelledAs life expectancy increases, more patients ≥65years undergo general anesthesia. Anesthetic agents may contribute to postoperative cognitive dysfunction, and incidence may differ with anesthetic agents or intraoperative anesthesia depth. Responses to anesthetic adjuvants vary among elderly patients. Processed electroencephalography guidance of anesthetic may better ensure equivalent cerebral suppression. This study investigates postoperative cognitive dysfunction differences in elderly patients given desflurane or sevoflurane using processed electroencephalography guidance.IRB approved, randomized trial enrolled consenting patients ≥65years scheduled for elective surgery requiring general anesthesia ≥120minute duration. After written informed consent, patients were randomly assigned to sevoflurane or desflurane. No perioperative benzodiazepines were administered. Cognitive impairment was measured by an investigator blinded to group assignment using mini-Mental Status Examination (MMSE) at baseline; 1, 6, and 24hours after the end of anesthesia. Mean arterial pressure was maintained within 20% of baseline. Anesthetic dose was adjusted to maintain moderate general anesthesia per processed electroencephalograpy (Patient State Index 25 to 50). The primary outcome measure was intergroup difference in MMSE change 1hour after anesthesia (median; 95% confidence interval).110 patients consented; 26 were not included for analysis (no general anesthesia; withdrew consent; baseline MMSE abnormality; inability to perform postoperative MMSE; data capture failure); 47 sevoflurane and 37 desflurane were analyzed. There were no significant differences in patient characteristics; intraoperative mean blood pressure (desflurane 86.4; 81.3 to 89.6 versus sevoflurane 82.5; 80.2 to 86.1mmHg; p = 0.42) or Patient State Index (desflurane 41.9; 39.0 to 44.0 versus sevoflurane 41.0; 37.5 to 44.0; p = 0.60) despite a lower MAC fraction in desflurane (0.82; 0.77 to 0.86) versus sevoflurane (0.96; 0.91 to 1.03; p

Methemoglobin is hemoglobin with iron in a ferric state instead of a ferrous state, thus unable to carry oxygen causing cyanosis and a left shift of the oxyhemoglobin dissociation curve. Methemoglobinemia, either congenital or acquired, is a rare clinical occurrence and can be life threatening for individuals with levels greater than 20%. Acquired methemoglobinemia has multiple etiologies and is commonly caused by topical anesthetic drugs such as benzocaine, prilocaine, and lidocaine. Nitrates, both topical and intravenous, can also precipitate clinically significant levels. The inherited form of methemoglobinemia is rare and generally presents early in life. Until recently, the only method for measuring methemoglobin levels was to send a blood sample for co-oximetry analysis. Conventional dual-wavelength pulse oximetry does not detect methemoglobin levels and its mearsurement of oxygen saturation becomes unreliable in the setting of even small levels of methemoglobin in the blood. Recently, a new mutiwavelength pulse co-oximeter was developed that enables the detection of methemoglobin and carboxyhemoglobin (Masimo RAD 57 pulse co-oximeter, Irvine, CA). After institutional review board approval, we performed a prospective study to determine the incidence of elevated methemoglobin levels in 500 patients on medications known to cause elevations in methemoglobin levels. All patients were screened using the new pulse co-oximeter to determine the methemoglobin levels. Patients with clinically significant elevations in methemoglobin levels were referred to clinicians for further evaluation and treatment. Of the patients screened, 498 patients had clinically insignificant methemoglobin levels. Two patients exposed to benzocaine, a topical anesthetic, were found to have serious elevations in methemoglobin levels. One patient with benzocaine toxicity was found to have initial methemoglobin levels of 38.9 to 45.8% using the pulse co-oximeter. This level was confirmed with co-oximetry analysis. The second patient was discovered just after the initiation of methylene blue therapy for a methemoglobin level of 24%. The results of this study demonstrate the need to monitor patients exposed to triggering medications. Both patients with elevated methemoglobin levels were successfully treated. Of these patients with benzocaine toxicity only one of them was recognized by clinicians prior to diagnosis using the pulse co-oximeter. The pulse co-oximeter is portable and small; it provides an opprtunity for early noninvasive diagnosis of high methemoglobin level at a low cost.

We evaluated the effects of CO2 embolism on end-tidal carbon dioxide (ETCO2) and compared four methods for detection of gas embolism. Fourteen pigs were monitored for CO2 embolism with transesophageal echocardiography (TEE), changes in ETCO2, changes in mean pulmonary artery pressure (MPAP), and precordial auscultation (AUSC). Serial injections of CO2 (ranging from 0.05 to 5.0 mL/kg) were performed in seven pigs (Group 1). In the other seven pigs, CO2 was infused at rates between 0.01 and 0.4 mL.kg-1.min-1 (Group 2). Positive responses were defined as an acute change in heart sounds (AUSC), visualization of gas bubbles in the right cardiac chambers on TEE, an increase in MPAP > or = 3 mm Hg, and an acute change (increase or decrease) in ETCO2 > or = 3 mm Hg. In both groups, positive responses to CO2 embolism were represented by an initial decrease in ETCO2. The frequency with which positive responses were observed revealed that TEE was the most sensitive method (P < 0.05), whereas no differences were found among the other methods. In conclusion, in this model, positive response to CO2 embolism was represented by a decrease in ETCO2. TEE was the most sensitive method of detection of CO2 embolism, and ETCO2, MPAP, and AUSC were equally sensitive.

Chez une fillette de 12 j transplantation d'un cœur de babouin. Recuperation postoperatoire excellente. Sa mort n'est pas en rapport avec des problemes techniques ou anesthesiques