Portable ultrasound devices in regional anesthesia: the brachial plexus block

Ultrasonography has received increasing attention in regional anesthesia in recent years because it allows visualization of the nerves, the needle, and the surrounding structures and makes it possible to monitor distribution of the local anesthetic. Ultrasound technology is unfamiliar to most anesthesiologists, unless they work with transesophageal echocardiography. Ultrasound-guided regional anesthesia relies entirely on the expertise of the person performing the technique and how that person interprets the images, though the latest portable ultrasound devices are ergonomically designed for fast, easy use, even by less experienced personnel. The high-frequency probes can identify the brachial plexus and produce excellent images of considerable educational value that differ only slightly from those provided by larger, more expensive equipment. Ultrasonography makes it possible to identify the brachial plexus, from the roots to the peripheral nerves of the arm. We describe the main approaches used in providing an ultrasound-guided brachial plexus block and explain the basic principles of ultrasound imaging.     

The accuracy of personal activity monitoring devices

Activity monitoring has important applications in orthopaedic and medical research. There is a paucity of information on device accuracy. Thirty adults tested the accuracy of 10 devices in 5 activities: walk 400-M, run 400-M, walk 10-M, ascend and descend 10 steps. A second protocol tested slow walking speeds at 1.0, 1.5, 1.8, and 2.0 MPH. The waist-based devices FitBit One and Omron HJ-321 were >90% accurate for all activities. The wristband devices and Smartphone Apps were <90% accurate for most activities. The StepWatch Activity Monitor was >95% accurate at lower cadence activities, but undercounted running by ~25%. Waist-based, dedicated activity monitors are highly accurate in a variety of activities.     

Core temperature monitoring with new ventilatory devices

Widespread use of new airway devices, such as the laryngeal mask airway (LMA) and the cuffed oropharyngeal airway (COPA), preclude measuring core temperature in the distal esophagus. Therefore, we tested the hypothesis that core temperature measured with a thermocouple positioned on a LMA or COPA is sufficiently accurate and precise for clinical use. Temperatures were recorded from thermocouples positioned on the cuffs of LMAs or COPAs in 36 patients scheduled for prolonged orthopedic surgery or therapeutic hyperthermia for cancer. These temperatures, recorded at 15-min intervals, were compared with simultaneously obtained nasopharynx and tympanic membrane temperatures. Data were compared by linear regression and the bias calculated. Temperatures measured on the LMA correlated well with both nasopharyngeal (r(2) = 0.94) and tympanic membrane (r(2) = 0.94) temperatures. Temperatures measured on the COPA also correlated well with those on the nasopharynx (r(2) = 0.97) and tympanic membrane (r(2) = 0.96). The fraction of temperatures that differed from nasopharynx temperature by more than +/-0.5 degrees C was 8% with LMA and 11% with COPA; the fraction of temperatures that differed from tympanic temperature by more than +/-0.5 degrees C was 7% with LMA and 10% with COPA. These results suggest that body temperature measured from the cuffs of COPA or LMAs is sufficiently accurate for routine clinical use. IMPLICATIONS: Temperatures measured on airway devices correlated well with independent measurements of core body temperature. Thus, body temperature measured on the cuffs of airway devices is sufficiently accurate for routine use.     

Cerebral monitoring devices: what we pay for

In this review paper, the authors analyse advantages, pitfalls and economical considerations related to depth of anaesthesia monitoring. They first describe the most widely distributed monitors in Europe, and the physiological basis of each index. The optimal use of those monitors and their demonstrated clinical benefits are detailed, as well as the circumstances that can lead to erroneous information or interpretation. Knowledge of patients and practitioners, as well as beliefs and expectations regarding depth of anaesthesia monitoring are discussed. Finally, the authors give their own opinion regarding the use of depth of anaesthesia monitoring, according to clinical benefit and economical considerations.     

Clinical accuracy of continuous hemoglobin oxygen saturation monitoring devices

Three devices used to measure hemoglobin oxygen saturation in the extracorporeal circuit were studied and compared to a control. The Baxter Bentley OxySat, Oximetrix Accusat, and Radiometer ABL4 blood gas monitor were compared to a control, the IL 282 Co-Oximeter. Fifty-one sample points were obtained during all phases of cardiopulmonary bypass with results as follows: table: see text. The Accusat was found to be a statistically more accurate means of monitoring hemoglobin oxygen saturations during cardiopulmonary bypass than the ABL4 and the OxySat. All devices had significant correlation with the control and with each other.     

Portable electronic devices as memory and organizational aids after traumatic brain injury: a consumer survey study

OBJECTIVE: To ascertain consumer experiences and attitudes regarding the use of portable electronic devices as memory and organizational aids after traumatic brain injury (TBI). DESIGN: Survey study. SETTING: Post-acute TBI rehabilitation programs, research registries. PARTICIPANTS: Eighty persons with moderate to severe TBI interviewed a median of 3.7 years postinjury. OUTCOME MEASURE: Survey administered in structured interview format, analyzed both quantitatively and qualitatively. RESULTS: Two thirds of participants reported regular use of computers, but fewer than one third had experience with hand-held computers or similar devices. Interest in using portable devices for everyday memory and organizational tasks was higher than the expressed need for improvement in participants' current strategies. Respondents expressed reliable preferences for key device features, including simplicity of use, technical support, and long-lasting battery power. Preferred functions included keeping track of money spent, remembering things to do, and remembering what other people say. CONCLUSION: Portable electronic devices are acceptable or desirable by consumers with moderate to severe TBI for use as compensatory aids.     

A comparison of five devices for the bedside monitoring of heparin therapy.

Five instruments were tested for their capacity to monitor heparin therapy on whole blood at the bedside. The instruments were 512 Coagulation Monitor (Ciba-Corning), Thrombotrack (Nycomed), Automated Coagulation Timer (Hemotec), Hemochron-ACT and Hemochron-APTT (International Technidyne Corporation). Fifty subjects with various levels of heparinisation were tested on each instrument and were also assayed for antithrombin III, fibrinogen, haematocrit, platelet count and plasma heparin level. The results were compared with a reference APTT performed on the Automated Coagulation Laboratory 300R (Instrumentation Laboratories). The Hemochron-ACT correlated least well. The Hemotec and Thrombotrack were unsuitable in a clinical setting because of pipetting requirements, although the Thrombotrack did correlate well with the reference parameters. The 512 Coagulation Monitor was the simplest to use, but its maximum response corresponded to the midpoint of the reference APTT therapeutic range. The Hemochron-APTT was simple to use, had an adequate response range and correlated well with reference parameters.     

Radiofrequency transmission to monitoring devices in the operating room: a simulation study

We evaluated radiofrequency (RF) transmission to various monitoring devices using circuits that simulated potentially hazardous conditions for patients in the operating room. Right heart ejection fraction (REF) pulmonary artery catheters, transesophageal atrial pacing stethoscopes, and temperature-sensing esophageal stethoscopes were subjected to RF transmission from an electrosurgery unit. Peak voltage and spark intensity were measured in circuits between the electrocautery dispersive pad and conductive elements of the various medical devices. All monitoring devices with an exposed conductive surface were found to have induced voltages and even spark generation. The ranking for peak voltage from least to most was as follows: disrupted esophageal stethoscope (620 volts), the transesophageal pacemaker (640 volts), and the REF pulmonary artery catheter (PAC) (680 volts). Peak voltage measurements of the REF PAC significantly decreased from 388 +/- 23 to 142 +/- 22 volts (P < 0.0001, Student's t-tests) in a fluid medium compared to air. In a fluid medium, peak voltage significantly decreased from 142 +/- 22 to 85 +/- 15 volts (P < 0.0001, Student's t-tests) when the REF PAC was connected to the cardiopulmonary monitor.     

Coagulation monitoring: current techniques and clinical use of viscoelastic point-of-care coagulation devices

Perioperative monitoring of blood coagulation is critical to better understand causes of hemorrhage, to guide hemostatic therapies, and to predict the risk of bleeding during the consecutive anesthetic or surgical procedures. Point-of-care (POC) coagulation monitoring devices assessing the viscoelastic properties of whole blood, i.e., thrombelastography, rotation thrombelastometry, and Sonoclot analysis, may overcome several limitations of routine coagulation tests in the perioperative setting. The advantage of these techniques is that they have the potential to measure the clotting process, starting with fibrin formation and continue through to clot retraction and fibrinolysis at the bedside, with minimal delays. Furthermore, the coagulation status of patients is assessed in whole blood, allowing the plasmatic coagulation system to interact with platelets and red cells, and thereby providing useful additional information on platelet function. Viscoelastic POC coagulation devices are increasingly being used in clinical practice, especially in the management of patients undergoing cardiac and liver surgery. Furthermore, they provide useful information in a large variety of clinical scenarios, e.g., massive hemorrhage, assessment of hypo- and hypercoagulable states, guiding pro- and anticoagulant therapies, and in diagnosing of a surgical bleeding. A surgical etiology of bleeding has to be considered when viscoelastic test results are normal. In summary, viscoelastic POC coagulation devices may help identify the cause of bleeding and guide pro- and anticoagulant therapies. To ensure optimal accuracy and performance, standardized procedures for blood sampling and handling, strict quality controls and trained personnel are required.     

Role of monitoring devices in prevention of anesthetic mishaps: a closed claims analysis

Anesthesiologist-reviewers examined 1,175 anesthetic-related closed malpractice claims from 17 professional liability insurance companies. The claims were filed between 1974 and 1988. The reviewers were asked to determine if the negative outcome was preventable by proper use of additional monitoring devices available at the time of the review even if not available at the time the incident occurred, and if so, which devices could have been preventative. In 1,097 cases sufficient information was available to make a judgment regarding preventability of the morbidity or mortality by application of additional monitoring devices. It was determined that 31.5% of the negative outcomes could have been prevented by application of additional monitors. Using the insurance industry's scale of 0 (no injury) to 9 (death), the median severity of injury for incidents deemed preventable was 9 compared with 5 for those deemed not preventable (P less than 0.01, scale detailed in text). The severity of injury scores were the same for preventable mishaps occurring during regional or general anesthesia, suggesting that additional monitoring devices may be equally efficacious in preventing serious negative outcomes during either regional or general anesthesia. The judgements or settlements of the incidents judged preventable by additional monitoring were 11 times more costly (P less than 0.01) than those mishaps not judged preventable. The monitors determined by the reviewers to be most useful in mishap prevention were pulse oximetry plus capnometry. Applied together, these two technologies were considered potentially preventative in 93% of the preventable mishaps.(ABSTRACT TRUNCATED AT 250 WORDS)     

French national survey of the use of monitoring devices during cardiopulmonary bypass in 2001

OBJECTIVES: To study the different monitoring devices used during cardiopulmonary bypass (CPB) and to determine the factors, which may influence the choice of these equipments. STUDY DESIGN: Survey. METHODS: A postal questionnaire was send to the 66 French cardiac surgery centres. Results have been analysed about the economic status (public health service or private institution) and the business of the centre (less than 500, between 500 to 800 and more than 800 cardiopulmonary bypass/year). RESULTS: The rate of answer reached 73%. In 40% of centres, the cardiovascular perfusionist was not alone during the procedure. The percentage of centres using a checklist was 80%, a neurologic monitoring 42%, anaesthesia depth monitoring 40%, venous reservoir level detector 52%, arterial line bubble detector 38%, cardioplegia circuit bubble detector 6%, transoesophageal echocardiography 48%, pipe's temperature monitoring 90%; oxymetry 44%, capnography 25%, SvO2 98%, blood gas analysis outside the OR 46% and computer records 35%. No difference was observed between public and private institution for these latter devices. However, a significant difference was noticed among the low, intermediate and highly busy centres for the use of checklist, the EEG monitoring, the pipe and water circuit temperature monitoring, capnography and location of the biologic analysers. CONCLUSION: Equipments were not similar among the different French cardiac surgery centres. Furthermore, the French practice seems different from American, UK and Australian's one. These results highlight the need of establishing French guidelines, which are absent.