Manual volume delivery via Frova Intubating Introducer: a bench research study.

PURPOSE: Oxygen delivery through a Frova Intubating Introducer may be life-saving, and gas flow characteristics through this device have been described. Nevertheless, the feasibility of using a self-inflating resuscitation bag to deliver air or oxygen through this device has not been assessed. We compared volumes of air delivered and peak pressures generated with normal and maximal bimanual compression of a self-inflating resuscitation bag connected to a 70 cm Frova Intubating Introducer. METHODS: In this bench research study, the proximal end of the 14-F Frova Intubating Introducer was connected to the self-inflating resuscitation bag, and the distal end was connected to a flow analyzer fitted with an adult test lung. Thirty-five anesthesia health care providers (staff/trainees) squeezed the self-inflating resuscitation bag with three normal and three maximal bimanual compressions. Endpoints of interest included the delivered volume of air and generated peak pressure. RESULTS: Normal bimanual compression resulted in a smaller mean (standard deviation) volume of air and peak pressure compared with maximal bimanual compression [554 (131) vs 955 mL (121); mean difference - 400.4; 95% confidence interval [CI], - 441.8 to - 359.0; P < 0.001; and 22.0 (3.4) vs 41.8 cmH2O (13.3); mean difference - 19.7; 95% CI, - 23.5 to - 15.9; P < 0.001, respectively]. CONCLUSION: Clinically useful, life-sustaining volumes of air can be delivered using normal and maximal bimanual compression of a self-inflating resuscitation bag connected to a 70 cm Frova Intubating Introducer. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02786355); registered 27 January, 2016.

RéSUMé: OBJECTIF: L'administration d'oxygène au travers d'un introducteur (bougie) Frova pour intubation peut sauver une vie et les caractéristiques du débit de gaz à travers ce dispositif ont été décrites précédemment. Néanmoins, la faisabilité de l'utilisation d'un ballon de réanimation pour administrer de l'air ou de l'oxygène à travers ce dispositif n'a pas été évaluée. Nous avons comparé des volumes d'air délivrés et les pressions maximales générées avec une compression bimanuelle normale ou maximale d'un ballon de réanimation autogonflant relié à un introducteur Frova pour intubation de 70 cm. MéTHODES: Dans cette étude expérimentale, l'extrémité proximale de l'introducteur Frova 14F pour intubation a été connectée au ballon de réanimation autogonflant et son extrémité distale a été connectée à un analyseur de débit adapté à un poumon adulte artificiel. Trente-cinq prestataires d'anesthésie (patrons/résidents) ont comprimé le ballon de réanimation avec trois compressions bimanuelles normales et trois compressions maximum. Les critères d'évaluation ont inclus le volume d'air délivré et la pression maximum générée. RéSULTATS: La compression bimanuelle normale a fourni un volume d'air moyen (ET) et une pression maximum moyenne (ET) inférieurs à la compression bimanuelle maximum (554 [131] contre 955 mL [121]; différence des moyennes, -400,4; intervalle de confiance [IC] à 95 % : ­441,8 à − 359,0; P < 0,001; et 22,0 [3,4] contre 41,8 cmH2O [13,3]; différence des moyennes, ­19,7; IC à 95 % : − 23,5 à − 15,9; P < 0,001). CONCLUSION: Des volumes d'air cliniquement utiles pour le maintien en vie peuvent être administrés par compression bimanuelle normale et maximum d'un ballon de réanimation autogonflant connecté à un introducteur Frova pour réanimation de 70 cm. ENREGISTREMENT DE L'ESSAI CLINIQUE: www.ClinicalTrials.gov (NCT02786355); enregistré le 27 janvier 2016.

A Prospective Observational Comparison Between Arm and Wrist Blood Pressure During Scheduled Cesarean Delivery.

BACKGROUND: Shivering is common during cesarean delivery (CD) under neuraxial anesthesia and may disrupt the measurement of noninvasive blood pressure (BP). BP measured at the wrist may be less affected by shivering. There have been no studies comparing trends in BP measured on the upper arm and wrist. We hypothesized that wrist systolic blood pressure (sBP) would accurately trend with upper arm sBP measurements (agree within a limit of ±10%) in parturients undergoing elective CD under spinal anesthesia or combined spinal-epidural anesthesia. METHODS: After initiation of spinal anesthesia, BP measurements were obtained simultaneously from the upper arm and wrist on opposite arms. The interval between measurements was 1 to 2 minutes, and data were collected for 20 minutes or until delivery. The primary outcome was agreement in dynamic changes in sBP measurements between the upper arm and the wrist. Bland-Altman plots indicating the levels of agreement between the methods were drawn for baseline measurements, over multiple measurements, and over multiple measurements on percentage change from baseline. RESULTS: Forty-nine patients were recruited and completed the study. The wrist sBP tended to overestimate the upper sBP for both baseline data (sBP bias = 13.4 mm Hg; 95% confidence interval = +10.4 to +16.4 mm Hg) and data obtained over multiple measurements (sBP bias = 12.8 mm Hg; 95% confidence interval = +9.3 to +16.3 mm Hg). For change in sBP from baseline over multiple measurements, the mean difference between the wrist and the arm sBP was -0.2 percentage points (99% limits of agreement -25 to +25 percentage points). CONCLUSIONS: The wrist measurement overestimated the reading relative to the upper arm measurement for multiple measurements over time. However, when the time series for each subject was examined for percentage change from baseline, the 2 methods mirrored each other in most cases. Nevertheless, our hypothesis was rejected as the limits of agreement were higher than ±10%. This finding suggests that wrist BP may not be an accurate method of detecting hypotension or hypertension during spinal or combined spinal-epidural anesthesia for CD.

The difficult airway with recommendations for management--part 2--the anticipated difficult airway.

BACKGROUND: Appropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway. METHODS: To review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned. PRINCIPAL FINDINGS: Previously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician's experience, must also be considered in deciding the appropriate strategy. CONCLUSIONS: With an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation.

The difficult airway with recommendations for management--part 1--difficult tracheal intubation encountered in an unconscious/induced patient.

BACKGROUND: Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group's mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered. METHODS: Nineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria. CONCLUSIONS: The clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative "Plan B" technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, "cannot intubate, cannot oxygenate" situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.

Single-operator real-time ultrasound-guidance to aim and insert a lumbar epidural needle.

PURPOSE: In conventional practice of epidural needle placement, determining the interspinous level and choosing the puncture site are based on palpation of anatomical landmarks, which can be difficult with some subjects. Thereafter, the correct passage of the needle towards the epidural space is a blind "feel as you go" method. An aim-and-insert single-operator ultrasound-guided epidural needle placement is described and demonstrated. METHOD: Nineteen subjects undergoing elective Cesarean delivery consented to undergo both a pre-puncture ultrasound scan and real-time paramedian ultrasound-guidance for needle insertion. Following were the study objectives: to measure the success of a combined spinal-epidural needle insertion under real-time guidance, to compare the locations of the chosen interspinous levels as determined by both ultrasound and palpation, to measure the change in depth of the epidural space from the skin surface as pressure is applied to the ultrasound transducer, and to investigate the geometric limitations of using a fixed needle guide. RESULTS: One subject did not participate in the study because pre-puncture ultrasound examination showed unrecognizable bony landmarks. In 18 of 19 subjects, the epidural needle entered the epidural space successfully, as defined by a loss-of-resistance. In two subjects, entry into the epidural space was not achieved despite ultrasound guidance.Eighteen of the 19 interspinous spaces that were identified using palpation were consistent with those determined by ultrasound. The transducer pressure changed the depth of the epidural space by 2.8 mm. The measurements of the insertion lengths corresponded with the geometrical model of the needle guide, but the needle required a larger insertion angle than would be needed without the guide. CONCLUSION: This small study demonstrates the feasibility of the ultrasound-guidance technique. Areas for further development are identified for both ultrasound software and physical design.

Effects of dredging in Göteborg harbor, Sweden, assessed by biomarkers in eelpout (Zoarces viviparus).

We used a battery of biomarkers in fish to study the effects of the extensive dredging in Göteborg harbor situated at the river Göta alv estuary, Sweden. Eelpout (Zoarces viviparus) were sampled along a gradient into Göteborg harbor, both before and during the dredging. Biomarker responses in the eelpout before the dredging already indicated that fish in Göteborg harbor are chronically affected by pollutants under normal conditions compared to those in a reference area. However, the results during the dredging activities clearly show that fish were even more affected by remobilized pollutants. Elevated ethoxyresorufin-O-deethylase activities and cytochrome P4501A levels indicated exposure to polycyclic aromatic hydrocarbons. Elevated metallothionein gene expression indicated an increase in metal exposure. An increase in general cell toxicity, measured as a decrease in lysosomal membrane stability, as well as effects on the immune system also could be observed in eelpout sampled during the dredging. The results also suggest that dredging activities in the Göta alv estuary can affect larger parts of the Swedish western coast than originally anticipated. The present study demonstrates that the application of a set of biomarkers is a useful approach in monitoring the impact of anthropogenic activities on aquatic environments.

Real-time ultrasound image classification for spine anesthesia using local directional Hadamard features.

PURPOSE: Injection therapy is a commonly used solution for back pain management. This procedure typically involves percutaneous insertion of a needle between or around the vertebrae, to deliver anesthetics near nerve bundles. Most frequently, spinal injections are performed either blindly using palpation or under the guidance of fluoroscopy or computed tomography. Recently, due to the drawbacks of the ionizing radiation of such imaging modalities, there has been a growing interest in using ultrasound imaging as an alternative. However, the complex spinal anatomy with different wave-like structures, affected by speckle noise, makes the accurate identification of the appropriate injection plane difficult. The aim of this study was to propose an automated system that can identify the optimal plane for epidural steroid injections and facet joint injections. METHODS: A multi-scale and multi-directional feature extraction system to provide automated identification of the appropriate plane is proposed. Local Hadamard coefficients are obtained using the sequency-ordered Hadamard transform at multiple scales. Directional features are extracted from local coefficients which correspond to different regions in the ultrasound images. An artificial neural network is trained based on the local directional Hadamard features for classification. RESULTS: The proposed method yields distinctive features for classification which successfully classified 1032 images out of 1090 for epidural steroid injection and 990 images out of 1052 for facet joint injection. In order to validate the proposed method, a leave-one-out cross-validation was performed. The average classification accuracy for leave-one-out validation was 94 % for epidural and 90 % for facet joint targets. Also, the feature extraction time for the proposed method was 20 ms for a native 2D ultrasound image. CONCLUSION: A real-time machine learning system based on the local directional Hadamard features extracted by the sequency-ordered Hadamard transform for detecting the laminae and facet joints in ultrasound images has been proposed. The system has the potential to assist the anesthesiologists in quickly finding the target plane for epidural steroid injections and facet joint injections.

Postoperative analgesia in video-assisted thoracoscopy: the role of intercostal blockade.

OBJECTIVES: This study examined (1) the opioid and nonopioid requirement of patients undergoing video-assisted thoracoscopy (VATS) as a measure of postoperative pain and (2) whether percutaneous intercostal blockade might reduce morphine requirements and improve analgesia in VATS procedures. DESIGN: A combined retrospective and prospective study. SETTING: A university teaching hospital. PARTICIPANTS: Patients undergoing VATS procedures. INTERVENTIONS: A retrospective analysis of 26 sequential patients; perioperative intercostal blockade with bupivacaine, either with or without dextran 40, in 26 prospective patients. MEASUREMENTS AND MAIN RESULTS: Retrospective: opioid and nonopioid analgesic requirements of 26 sequential patients who had undergone VATS surgery without intercostal blockade were determined from a study of the case records. Twenty-six additional patients undergoing VATS surgery by the same surgeon were randomly divided to receive either percutaneous intercostal nerve block using plain bupivacaine 0.375% or bupivacaine 0.375% in dextran 40. The duration of local anesthesia was assessed. Postoperative opioid and nonopioid analgesic requirements were compared with the retrospective group. CONCLUSIONS: Postoperative morphine requirements after VATS surgery are considerable, with pleurectomy being the most painful procedure. Intercostal blockade with bupivacaine provided effective pain relief and a dramatic reduction in morphine requirements. This technique is recommended for VATS surgery, especially if day-case procedures are being contemplated.