Daniel Boudreault

Ultrasound guidance speeds execution and improves the quality of supraclavicular block.

In this prospective study, we assessed the quality, safety, and execution time of supraclavicular block of the brachial plexus using ultrasonic guidance and neurostimulation compared with a supraclavicular technique that used anatomical landmarks and neurostimulation. It was hypothesized that ultrasonic guidance would increase the proportion of successful blocks, decrease block execution time, and reduce the incidence of complications such as pneumothorax and neuropathy. Eighty patients were randomized into two groups of 40, Group US (supraclavicular block guided in real time by a two-dimensional ultrasonic image, with neurostimulator confirmation of correct needle position) and Group NS (supraclavicular block using the subclavian perivascular approach, also with neurostimulator confirmation). Blocks were performed using bupivacaine 0.5% and lidocaine 2% (1:1 vol) with epinephrine 1:200,000 as the anesthetic mixture. The onset of motor and sensory block for the musculocutaneous, median, radial, and ulnar nerves was evaluated over a 30 min period. At 30 min 95% of patients in Group US and 85% of patients in Group NS had a partial or complete sensory block of all nerve territories (P = 0.13) and 55% of patients in Group US and 65% of patients in Group NS had a complete block of all nerve territories (P = 0.25). Surgical anesthesia without supplementation was achieved in 85% of patients in Group US and 78% of patients in Group NS (P = 0.28). No patient in Group US and 8% of patients in Group NS required general anesthesia (P = 0.12). The quality of ulnar block was significantly inferior to the quality of block in other nerve territories in Group NS, but not in Group US; the quality of ulnar block was not significantly different between Groups NS and US. The block was performed in an average of 9.8 min in Group NS and 5.0 min in Group US (P = 0.0001). No major complication occurred in either group. We conclude that ultrasound-guided neurostimulator-confirmed supraclavicular block is more rapidly performed and provides a more complete block than supraclavicular block using anatomic landmarks and neurostimulator confirmation.

Detection of gas embolism by transesophageal echocardiography during laparoscopic cholecystectomy

Using transesophageal echocardiography (TEE), 16 patients (ASA physical status I-III), undergoing laparoscopic cholecystectomy, were assessed for the occurrence of episodes of gas embolism and cardiovascular changes related to those emboli. The long-axis four-chamber view was monitored continuously, except for predetermined intervals where the transgastric short-axis view was obtained to derive the end-diastolic area (EDA), the end-systolic area (ESA), and the ejection fraction (EF). In one patient, we monitored the longitudinal view of the superior and the inferior vena cava. The monitoring of the patients also included: heart rate (HR), mean arterial pressure (MAP), arterial saturation by pulse oximetry (SpO2), end-tidal CO2 (ETCO (2)), minute ventilation (VE), and peak inspiratory pressure (PIP). Embolic events were defined as the appearance of gas bubbles in the right cardiac chambers. We observed gas embolism in 11/16 patients (five during peritoneal insufflation and six during gallbladder dissection). Using the longitudinal view of the superior and inferior vena cava (IVC), we found that these emboli were transmitted through the IVC. No episode of cardiorespiratory instability (decrease in MAP >or=to 10 mm Hg, SpO2 < 90%) was observed. There was no significant difference in cardiorespiratory variables between patients who presented gas embolism (n = 11) and patients who did not (n = 5) during the studied period. In this small group of patients, we conclude that gas embolism occurs commonly during laparoscopic cholecystectomy but that these gas emboli cause minimal cardiorespiratory instability. (Anesth Analg 1996;82:119-24)

Scalp nerve blocks decrease the severity of pain after craniotomy

Up to 80% of patients report moderate to severe pain after craniotomy. In this study, we assessed the efficacy of scalp block for decreasing postoperative pain in brain surgery. Thirty patients scheduled for supratentorial craniotomy were enrolled. They were randomly divided into two groups: Ropivacaine (scalp block with 20 mL of ropivacaine 0.75%) and Saline (scalp block with 20 mL of saline 0.9%). Anesthesia was standardized. The scalp block was performed after skin closure and before awakening. Postoperative pain was assessed at 4, 8, 12, 16, 20, 24, and 48 h by using a 10-cm visual analog scale. Analgesia was provided with sub- cutaneous codeine as requested by the patient. Average visual analog scale scores were higher in the Saline group as compared with Ropivacaine (3.7 ± 2.4 vs 2.0 ± 1.6;P = 0.036). The total dose of codeine did not differ, nor did the duration of time before the first dose of codeine was required in the Ropivacaine (571 ± 765 min) versus Saline (319 ± 409 min;P = 0.17) group. In conclusion, we found that postoperative scalp block decreases the severity of pain after craniotomy and that this effect is long lasting, possibly through a preemptive mechanism.

Impact of routine use of intraoperative transesophageal echocardiography during cardiac surgery

PurposeTo determine the relative impact of each category-based TEE indication according to the ASA guidelines.MethodsIn 851 patients undergoing cardiac surgery, TEE clinical indications were classified as category I or II according to the ASA guidelines. Category 1 indications are patients in which TEE is considered useful and category II are those where TEE is potentially useful but indications are less clear. All TEE examinations were reviewed by two anesthesiologists with advanced training in TEE. For each patient, the clinical impact of TEE in the clinical management was assessed using five criteria: 1) change of medical therapy; 2) change in the surgical procedure; 3) confirmation of a suspected diagnosis; 4) positioning of an intravascular device, and 5) substitute to a pulmonary artery catheter (PAC).ResultsTEE had greater utility in category I than in category II indications (15/53 (28%)vs 110/798 (14%) respectively) (P < 0.01). The nature of the clinical impact was as follows: modification of medical therapy in 67/125 (53%), modification of planned surgical intervention in 38/125 (30%), confirmation of a diagnosis in 34/125 (27%). The impact on therapy was higher in complex surgical procedures (39%) than in valvular replacement (19%) (P < 0.01) and coronary artery bypass surgery (10%) (P < 0.001).ConclusionsOur findings validate the usefulness of the ASA practice guidelines demonstrating a greater impact of TEE on clinical management for category I indications than for category II. TEE also had a greater clinical impact in complex surgical procedures and in valvular replacement.RésuméObjectifDéterminer l’effet relatif de l’indication de l’ETO basée sur chacune des catégories relevant des recommandations ASA.MéthodeChez 851 patients devant subir une intervention chirurgicale cardiaque, les indications cliniques de l’ETO ont été classées en catégorie I ou II selon les recommandations de l’ASA. Dans la catégorie I, ce sont les patients pour qui l’ETO est considérée utile et dans la catégorie II, ceux pour qui l’ETO est probablement utile, les indications n’étant pas aussi claires. Tous les examens d’ETO ont été révisés par deux anesthésiologistes de formation poussée en ETO. Les répercussions cliniques de l’ETO sur le traitement clinique de chaque patient ont été évaluées selon cinq critères: 1) la modification du traitement médical 2) un changement de technique chirurgicale 3) la confirmation d’un diagnostic présumé 4) la mise en place d’un appareil intravasculaire 5) un substitut au cathéter de l’artère pulmonaire (CAP).RésultatsL’ETO a présenté une plus grande utilité avec les indications de catégorie 1 qu’avec celles de catégorie II (15/53 (28 %) vs 110/798 (14 %) respectivement) (P < 0,01). La nature de l’effet clinique a été : une modification de traitement médical chez 67/125 (53 %), un changement d’intervention chirurgicale chez 38/125 (30 %), la confirmation d’un diagnostic chez 34/125 (27 %). Les conséquences sur le traitement ont été plus grandes pour des interventions chirurgicales complexes (39 %) que pour le remplacement valvulaire (19 %) (P < 0,01) et le pontage aortocoronarien (10 %) (P < 0,001).ConclusionNos résultats confirment l’utilité des recommandations de pratique de l’ASA qui démontrent une plus grande influence de l’ETO sur le traitement clinique pour les indications de catégorie I que pour celles de catégorie II. L’ETO a aussi un effet plus important sur les interventions chirurgicales complexes et sur le remplacement valvulaire.

Perioperative use of transesophageal echocardiography by anesthesiologists: Impact in noncardiac surgery and in the intensive care unit

BackgroundThe American Society of Anesthesiologists (ASA) has published practice guidelines for the use of perioperative transesophageal echocardiography (TEE) but the role and impact of TEE performed by anesthesiologists outside the cardiac operating room (OR) is still poorly explored. We report our experience in the use of TEE in the noncardiac OR, the recovery room and in the intensive care unit (ICU) in a university hospital, and analyze the impact of TEE on clinical decision making.MethodsTwo hundred fourteen patients were included and TEE indications were classified prospectively according to the ASA guidelines. The examinations and data sheets were reviewed by two anesthesiologists with advanced training in TEE. For each examination, it was noted if TEE altered the management according to five groups: 1) changing medical therapy; 2) changing surgical therapy; 3) confirmation of a diagnosis; 4)positioning of an intravascular device; and 5) TEE used as a substitute to a pulmonary artery catheter.ResultsEighty-nine (37%), 67 (31%) and 58 (27%) patients had category I, II and III indications. The impact was more significant in category I where TEE altered therapy 60% of the time compared with 31% and 21% for categories II and III (P < 0.001). The most frequent reason for changing management was a modification in medical therapy in 53 instances (45%).ConclusionOur results confirm a greater impact of TEE performed by anesthesiologists on clinical management for category I compared to category II and III indications in the noncardiac OR surgical setting and in the ICU.RésuméContexteL’American Society of Anesthesiologists (ASA) a publié lelignes directrices pour l’utilisation périopératoire de l’échocardiographie transœsophagienne (ETO), mais le rôle et l’impact de l’ETO réalisée par les anesthésiologistes à l’extérieur de la salle d’opération (SO) sont encore peu connus. Nous présentons notre expérience de l’usage de l’ETO dans une SO non cardiaque, dans la salle de réveil et à l’unité des soins intensifs (USI) d’un hôpital universitaire. Aussi, nous analysons l’impact de l’ETO sur la prise de décision en clinique.MéthodeDeux cent quatorze sujets ont participé à l’étude et les indications d’ETO ont été classifiées prospectivement selon les lignes directrices de l’ASA. Les examens et les fiches techniques ont été passées en revue par deux anesthésiologistes de formation avancée en ETO. Pour chaque examen, on a noté si l’ETO modifiait le traitement en regard de cinq groupes: 1) modification de la thérapie médicale 2) modification de la thérapie chirurgicale 3) confirmation du diagnostic 4) installation d’une sonde intravasculaire 5) usage de l’ETO comme substitut d’un cathéter artériel pulmonaire.RésultatsQuatre-vingt-neuf (37 %), 67 (31 %) et 58 (27 %) patients présentaient des indications de catégorie I, II et III. L’ETO a eu un impact plus significatif pour la catégorie I où elle modifiait la thérapie dans 60 % des cas comparativement à 31 % et à 21 % pour les catégories II et III (P < 0,001). C’est la modification de la thérapie médicale qui apparaît comme la raison principale de changement du traitement avec 53 cas (45 %).ConclusionNos résultats confirment une plus grande répercussion de l’ETO réalisé par les anesthésiologistes sur le traitement clinique pour les indications de catégorie I comparées à celles de catégories II et III dans le contexte chirurgical d’une SO non cardiaque et de l’USI.

Ultrasound-guided infraclavicular versus supraclavicular block.

In this prospective study we compared ultrasound-guided (USG) infraclavicular and supraclavicular blocks for performance time and quality of block. We hypothesized that the infraclavicular approach would result in shorter performance times with a quality of block similar to that of the supraclavicular approach. Eighty patients were randomized into two equal groups: Group I (infraclavicular) and Group S (supraclavicular). All blocks were performed using ultrasound visualization with a 7.5-MHz linear probe and neurostimulation. The anesthetic mixture consisted of 0.5 mL/kg of bupivacaine 0.5% and lidocaine hydrocarbonate 2% (1:3 vol.) with epinephrine 1:200,000. Sensory block, motor block, and supplementation rates were evaluated for the musculocutaneous, median, radial, and ulnar nerves. Surgical anesthesia without supplementation was achieved in 80% of patients in group I compared with 87% in Group S (P = 0.39). Supplementation rates were significantly different only for the radial territory: 18% in Group I versus 0% in group S (P = 0.006). Block performance times were not different between groups (4.0 min in Group I versus 4.65 min in Group S; P = 0.43). Technique-related pain scores were not different between groups (I: 2.0; S: 2.0; P = 1.00). We conclude that USG infraclavicular block is at least as rapidly executed as USG supraclavicular block and produces a similar degree of surgical anesthesia without supplementation.

Epidural analgesia and intravenous patient-controlled analgesia result in similar rates of postoperative myocardial ischemia after aortic surgery

To assess the role of postoperative analgesia on myocardial ischemia after aortic surgery, we compared intravenous patient-controlled analgesia (PCA) with thoracic epidural analgesia (TEA). One hundred twenty-four patients were prospectively randomized to the PCA or TEA group. In the TEA group, a T6-7 or T7-8 epidural catheter was inserted before the induction of general anesthesia. Within 1 h of the end of surgery, analgesia and 24-h two-channel Holter monitoring were begun. Myocardial ischemia was defined as ST segment depression >or=to1 mm, 0.06 s after the J point, and lasting for more than 1 min. In the PCA group, a bolus of morphine, 0.05 mg/kg, was given, followed by 0.02 mg/kg of morphine on demand every 10 min. Bupivacaine 0.125% and fentanyl 10 micro g/mL was used in the TEA group. Analgesics were titrated to maintain a visual analog scale score <or=to3. The overall incidence of myocardial ischemia was 18.4%-18.2% for TEA and 18.6% for PCA (P = not significant). There were no differences between the groups in the total duration of ischemia per patient (22.2 +/- 119.8 min for TEA and 20.5 +/- 99 min for PCA) and the number of episodes per patient (0.69 +/- 2.1 for TEA and 1.2 +/- 4.9 for PCA). Twenty-three patients had an adverse cardiac outcome, although there were no differences between the groups. The postoperative pain control was superior with TEA. In these patients undergoing elective aortic surgery, the use of postoperative TEA did not result in a lower incidence of early myocardial ischemia compared with intravenous PCA with morphine, despite better analgesia with TEA. Implications: Postoperative myocardial ischemia is associated with adverse cardiac outcome. Using Holter monitoring after aortic surgery, this study shows that the use of thoracic epidural analgesia with bupivacaine and fentanyl did not result in a lower incidence of myocardial ischemia compared with intravenous patient-controlled analgesia with morphine. (Anesth Analg 1997;85:1233-9)

Venous carbon dioxide embolism in pigs: an evaluation of end-tidal carbon dioxide, transesophageal echocardiography, pulmonary artery pressure, and precordial auscultation as monitoring modalities.

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.

Incidences of Venous Air Embolism and Patent Foramen Ovale among Patients Undergoing Selective Peripheral Denervation in the Sitting Position

OBJECTIVEThe incidence and severity of venous air embolism (VAE), a potentially fatal complication, among patients undergoing selective peripheral denervation in the sitting position have never been clearly established. We designed this retrospective study to assess the incidence and severity of VAE, the incidence of paradoxical air embolism, and the occurrence of patent foramen ovale, as detected with transesophageal echocardiography, as well as the effects of its detection on patient treatment. METHODSAfter institutional review board approval, data were collected from the charts of all patients who underwent selective peripheral denervation at our institution between 1988 and 2001. The severity of VAE was assessed by using a 5-point scale. RESULTSData for 342 patients were available for analyses. Seven patients exhibited VAE, yielding an incidence of 2%. The severity of VAE was 2/5 for three patients, 3/5 for three patients, and 4/5 for one patient. Air could be aspirated from the central venous catheter for three patients. No deaths occurred. Among the 96 transesophageal echocardiographic examinations performed, 5 cases of patent foramen ovale were detected (5.2%). For those patients, surgery was performed in the prone or park-bench position. No paradoxical air embolism was detected. CONCLUSIONThis is the first large study to directly assess the incidence and severity of VAE among patients undergoing selective peripheral denervation in the sitting position. We recommend that the detection of a patent foramen ovale prompt a change in position for this surgical procedure.

Craniotomy site influences postoperative pain following neurosurgical procedures: a retrospective study

ObjectiveThis retrospective study was designed to assess the intensity of postoperative pain in relation to the location of craniotomy.MethodsAfter Research Ethics Board approval, data were collected from the charts of all patients who underwent a craniotomy at our institution between January 2004 and December 2005. The severity of post-craniotomy pain was assessed by collecting scores obtained using an 11-point verbal rating scale and calculating the cumulative analgesic requirements for the first 48 hr postoperatively. Data were compared according to the craniotomy location.ResultsData from 299 patients was available for analysis. On average, 76% of patients experienced moderate to severe postoperative pain. Frontal craniotomy was associated with lower pain scores than four of six craniotomy sites analyzed, with 49% of patients reporting mild pain, a significant difference (P < 0.05) compared with all other groups except for parietal craniotomies. Frontal craniotomy patients also had lower opioid analgesic requirements compared to patients who underwent posterior fossa craniotomy (P < 0.05). Logistic regression analysis showed that craniotomy location (P < 0.0001 ) and age (P = 0.004) were both independent predictors of the intensity of postoperative pain, with lower pain scores as age increased. Postoperative use of steroids, gender and presence of preoperative pain were not statistically linked to postoperative pain intensity. The prevalence of postoperative nausea and vomiting was 56% and it did not vary according to the location of craniotomy.ConclusionThis study shows that the intensity of postoperative pain in neurosurgery is affected by the site of craniotomy. Frontal craniotomy patients experienced the lowest pain scores, and required significantly less opioid than patients undergoing posterior fossa interventions.ObjectifCette étude rétrospective a été conçue pour évaluer l’intensité de la douleur postopératoire par rapport au site de craniotomie.MéthodeAvec l’accord du Comité d’éthique de la recherche, les données des dossiers de tous les patients ayant subi une craniotomie dans notre institution entre janvier 2004 et décembre 2005 ont été compilées. La sévérité de la douleur suite à la craniotomie a été évaluée en récoltant les scores obtenus à l’aide d’une échelle d’évaluation verbale de 11 points et en calculant les besoins analgésiques cumulatifs pour les 48 heures suivant l’opération. Les données ont été comparées selon l’emplacement de la craniotomie.RésultatsLes données de 299 patients étaient disponibles pour analyse. En moyenne, 76 % des patients ont ressenti des douleurs postopératoires modérées à sévères. La craniotomie frontale était associée à des scores de douleur plus bas que quatre des six sites de craniotomie évalués, avec 49 % des patients signalant une douleur légère, une différence significative (P < 0,05) comparée à tous les autres groupes hormis les craniotomies pariétales. Les patients ayant subi une craniotomie frontale présentaient également des besoins plus faibles en analgésiques opiacés par rapport aux patients ayant subi des craniotomies de la fosse postérieure (P < 0,05). Une analyse par régression logistique a montré que l’emplacement de la craniotomie (P < 0,001) ainsi que l’âge (P = 0,004) constituent tous deux des prédicteurs indépendants de l’intensité de la douleur postopératoire, les scores de douleur étant plus bas chez les patients plus âgés. L’utilisation postopératoire de stéroïdes, le sexe et la présence de douleur préopératoire n’étaient pas statistiquement associés à l’intensité de la douleur postopératoire. La prévalence de nausées et de vomissements postopératoires était de 56 % et n’était pas affectée par le site de la craniotomie.ConclusionCette étude démontre que l’intensité de la douleur postopératoire en neurochirurgie est affectée par le site de craniotomie. Les patients ayant subi une craniotomie frontale ont obtenu les scores de douleur les plus bas, et leurs besoins en opiacés ont été significativement moindres que chez les patients ayant subi des interventions sur la fosse postérieure.