Bruce Crider

A comparison of superficial versus combined (superficial and deep) cervical plexus block for carotid endarterectomy: a prospective, randomized study.

Carotid endarterectomy may be performed by using cervical plexus blockade with local anesthetic supplementation by the surgeon during surgery. Most practitioners use either a superficial cervical plexus block or a combined (superficial and deep) block, but it is unclear which offers the best operative conditions or greatest patient satisfaction. We compared the two techniques in patients undergoing carotid endarterectomy. Forty patients undergoing carotid endarterectomy were randomized to receive either a superficial or a combined cervical plexus block. Bupivacaine 0.375% to a total dose of 1.4 mg/kg was used. The main outcome measure was the amount of supplemental lidocaine 1% used by the surgeon. Subsidiary outcome measures were postoperative pain score, sedative and analgesic requirements before and during surgery, and postoperative analgesic requirements. Median supplemental lidocaine requirements were 100 mg (range 30–180 mg) in the superficial block group and 115 mg (range 30–250 mg) in the combined block group. These differences were not statistically significant (Mann-Whitney U-test). There was no significant difference in the number of patients needing postoperative analgesia between the groups (11 of 20 in the deep block group versus 8 of 20 in the superficial block group) in the 24 h after surgery. The median time to first analgesia in the superficial block group was 150 min, more than in the combined block group (median time 45 min) but this difference, although large, was not statistically significant (Mann-Whitney U-test). We found no significant differences between the anesthetic techniques studied. All patients reported satisfaction with the techniques. Implications Carotid endarterectomy may be performed satisfactorily by using either superficial or combined block, and it is found that peroperative lidocaine requirements will be the same regardless of which block is used. The decision to use one block or the other might, therefore, reasonably be influenced by the relative safety of the superficial block compared with the combined block, because previous work suggests the deep injection is associated with a more frequent complication rate.

Changes in arterial oxygen saturation in cigarette smokers following general anaesthesia

The effect of cigarette smoking on postoperative arterial oxygen saturation was evaluated in 45 adult patients using pulse oximetry. Patients were divided into a smoking group (n = 20) and a non-smoking group (n = 25) based on current smoking habits up until the time of surgery. The two groups were similar with respect to sex, ASA physical status, surgical procedure, duration of anaesthesia, narcotic and anaesthetic use and recovery characteristics. The non-smoking group was, however, significantly (P < 0.05) older than the smoking group. Postoperative oxygen saturation (SaO2) decreased (P < 0.001) during transport of both groups of patients from the Operating Room to the Recovery Room; a decrease which was significantly greater in the smoking group. The severity of hypoxaemia was also significantly greater in the smoking group than in the non-smoking group. This study suggests that cigarette smoking contributes to postoperative arterial oxygen desaturation following general anaesthesia and that supplemental oxygen should be administered to these patients during postoperative transport.RésuméA l’aide d’un saturomètre digital, nous avons évalué l’effet du tabagisme sur la saturation artérielle en oxygène (SaO2) post-opératoire. Vingtcinq fumeurs de cigarette constituaient un groupe tandis que l’autre groupe était composé de vingt non-fumeurs. Les deux groupes étaient comparables quant au sexe, la classe ASA, le type d’intervention, la durée et le type d’anesthésie, les morphiniques utilisés et la récupération en salle de réveil. Toutefois, les non-fumeurs étaient plus agés que les fumeurs (P < 0,05). Chez les deux groupes, la SaO2 diminuait (P < 0,001) pendant le transport entre la salle d’opération et la salle de réveil quoique de façon significativement plus marquée chez les fumeurs. Le degré d’hypoxémie atteint était aussi plus sérieux chez les fumeurs. Il semble donc que la consommation de cigarettes contribue à l’hypoxémie post-opératoire observé après une anesthésie générate et que les fumeurs devraient respirer un mélange enrichi d’oxygène pendant leur transport vers la salle de réveil.

Effects of differing rates of protamine reversal of heparin anticoagulation

BACKGROUND Protamine sulfate reversal of heparin anticoagulation may be associated with adverse cardiovascular side effects. The purpose of this study was to determine whether diminished systemic oxygen consumption and hemodynamic changes were more likely to accompany rapid versus slow protamine administration. METHODS Fifteen patients undergoing abdominal aortic aneurysm resection in a prospective randomized double-blinded study received intravenous protamine (1.5 mg/kg) rapidly during a 3-minute period (group I, n = 7) or slowly during a 15-minute period (group II, n = 8). Systemic oxygen consumption (VO2) and hemodynamic parameters were assessed for up to 20 minutes after protamine administration began. RESULTS Blood pressure declines (millimeters of mercury) were greatest in group I with rapid protamine administration (-19 systolic and -9 diastolic) compared with group II with slow protamine administration (-12 systolic and -1 diastolic). Heart rate fell markedly in both groups I and II. Cardiac output (CO) declined in group I at virtually all time periods. Similar CO declines in group II occurred 10 minutes after protamine infusion had begun and persisted for 3 minutes after protamine administration was complete. Maximum VO2 decreases were -16% (60 seconds into protamine infusion) and -13% (1.5 minutes after protamine infusion) in groups I and II, respectively, with statistically significant declines (p < 0.05) occurring only in group I compared with baseline values. Statistically significant differences (p < 0.01), however, were found when mean declines during and after protamine infusion were compared with controls for both CO and VO2 in both groups. CONCLUSIONS Significant declines in systemic VO2 and hemodynamic perturbations accompany protamine reversal of heparin anticoagulation during aortic surgery. Rapid protamine administration increases the magnitude of these adverse responses.

An unusual manifestation of pulmonary artery perforation during pulmonary artery catheter insertion

P ULMONARY ARTERY balloon-tipped catheters are commonly inserted in critically ill patients as a source of physiologic data useful in planning management and evaluating the efficacy of treatment. Pulmonary artery perforation with resultant massive hemoptysis is a known complication of the use of these catheters, with an occurrence of 0.064% in one large series.’ The perforations with hemorrhage reported in this series occurred during the period after insertion rather than during actual insertion of the catheter. Various mechanisms for pulmonary artery injury during the insertion of these catheters have been proposed,* but no incidence for pulmonary artery injury during insertion has been reported. A case is reported which describes the immediate production of organized blood clots after pulmonary artery rupture during insertion and positioning of a pulmonary artery balloon-tipped catheter.

A comparison of superficial versus combined (superficial and deep) cervical plexus block for carotid endarterectomy: a prospective, randomized study. (University of Michigan Medical Center, Ann Arbor, MI) Anesth Analg 2000;91:781–786.

Carotid endarterectomy may be preformed by using cervical plexus blockade with local anesthetic supplementation by the surgeon during surgery. Most practitioners use either a superficial cervical plexus block or a combined (superficial and deep) block, but it is unclear which offers the best operative conditions or greatest patient satisfaction. This study compared the 2 techniques in 40 patients undergoing carotid endarterectomy. The patient randomly received either a superficial or a combined cervical plexus block. Bupivacaine 0.375% to a total dose of 1.4 mg/kg was used. The main outcome measure was the amount of supplemental lidocaine 1% used by the surgeon. Subsidiary outcome measures were postoperative pain score, sedative and analgesic requirements before and during surgery, and postoperative analgesic requirements. Median supplemental lidocaine requirements were 100 mg in the superficial block group and 115 mg in the combined block group. These differences were not statistically significant. There was no significant difference in the number of patients needing postoperative analgesia between the groups in the 24 h after surgery. The median time to first analgesia in the superficial block group was 150 min. more than in the combined block group, but this difference, although large, was not statistically significant. No significant differences were found between the anesthetic techniques studied. Comment by Alan Kaye, M.D. Carotid endarterectomy surgery can be performed with regional or general anesthesia. It is probable that a substantial majority of CEAs performed in North America are performed under general anesthesia. Debate over choice of regional versus general anesthesia persists because of various studies of risks and benefits. Each type of anesthesia has its own advantages and disadvantages, which must be considered when choosing the optimal anesthetic for patients. Regional anesthetic techniques available include local infiltration, superficial and deep cervical plexus block, a combination of these with or without contralateral superficial plexus, and cervical epidural anesthesia. This prospective, randomized, double-blinded study compared superficial versus combined (superficial and deep) cervical plexus block in 40 patients. Outcomes were measured by supplemental local anesthetic used by the surgeon, postoperative pain scores, and sedative and analgesic requirements before, during, and postoperatively. The results showed no significant difference in either study group. Therefore, this small study suggests that superficial block should be preferred in as much that it is relatively easy to do and the potential side-effects are far less than deep cervical block. Larger studies are warranted in this difficult population of patients.