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

Regional Anesthesia Techniques in Modern Neuroanesthesia Practice: A Narrative Review of the Clinical Evidence

Neurosurgical procedures are often associated with significant postoperative pain that is both underrecognized and undertreated. Given the potentially undesirable side effects associated with general anesthesia and with various pharmacological analgesic regimens, regional anesthetic techniques have gained in popularity as alternatives for providing both anesthesia and analgesia for the neurosurgical patient. The aim of this narrative review is to present an overview of the regional techniques that have been incorporated and continue to be incorporated into modern neuroanesthesia practice, presenting in a comprehensive way the evidence, where available, in support of such practice for the neurosurgical patient.

Regional Anesthesia for Vascular Surgery and Pain Management

Patients undergoing vascular surgery tend to have significant systemic comorbidities. Vascular surgery itself is also associated with greater cardiac morbidity and overall mortality than other types of noncardiac surgery. Regional anesthesia is amenable as the primary anesthetic technique for vascular surgery or as an adjunct to general anesthesia. When used as the primary anesthetic, regional anesthesia techniques avoid complications associated with general anesthesia in this challenging patient population. In this article, the authors describe regional anesthetic techniques for carotid endarterectomy, arteriovenous fistula creation, lower extremity bypass surgery, and amputation.

Anastomoses (Superficial Cervical Ansa) Between the Cervical Plexus and Peripheral Facial Nerve Branches: Implications for Regional Anesthesia in Carotid Endarterectomies - Anatomical Study

Purpose

Sensory innervation in the carotid triangle involves the cervical plexus, cranial nerves, and the sympathetic trunk. This innervation also applies to skin incision, including various anatomical structures with potentially different innervation, such as the skin (dermatomes), the platysma (myotomes), and the superficial layer of the cervical fascia (fasciotomes), as well as retromandibular retractor insertion (co-innervation: V, VII). The aim of this anatomical study was to develop an injection technique for carotid endarterectomies to additionally block anastomoses between the transverse cervical nerve (TCN), the cervical branch VII (CB VII), and the marginal mandibular branch VII (MMB VII). These anastomoses are also termed superficial cervical ansa (SCA).

Materials and Methods

Preparations (n=16) were performed on unembalmed donor cadavers (n=8). Subplatysmal injections (each using 5 mL of Alcian blue) were performed cranially within the carotid triangle between the anterior margin of the sternocleidomastoid muscle and the submandibular gland.

Results

Anastomoses between the TCN, CB VII, and MMB VII were stained in all preparations (n=16).

Conclusion

This anatomical study presents an ultrasound-guided subplatysmal SCA block to optimize, in addition to a cervical plexus block, the quality of anesthesia for carotid endarterectomies.

Influence of Anatomic Conditions on Efficacy and Safety of Combined Intermediate Cervical Plexus Block and Perivascular Infiltration of Internal Carotid Artery in Carotid Endarterectomy: A Prospective Observational Trial

Ultrasound-guided intermediate cervical plexus blockade with perivascular infiltration of the carotid artery bifurcation perivacular block (PVB) is a reliable technique for regional anesthesia in carotid endarterectomy (CEA). We investigated the effect of the carotid bifurcation level (CBL) on PVB efficacy and safety in patients undergoing CEA. This prospective observational cohort study included 447 consecutive CEA patients who received PVB over a 6-y period. Vascular and neurologic puncture-related complications were recorded. The CBL was localized at the low level (C4 and C5 vertebra, low-level [LL] group) in 381 (85.2%) patients and at the high level (C2 and C3 vertebra, high-level [HL] group) in 66 (14.8%) patients. Local anesthetic supplementation by surgeons was necessary in 64 (14.3%) patients in the LL group and 38 (59.4%) patients in the HL group (p < 0.001) and was associated with a higher rate of central neurologic complications in the HL group (p = 0.031). Therefore, the efficacy of the PVB may be influenced by the CBL.

Regional Anesthesia in Neuroanesthesia Practice

Regional anesthesia has been an undervalued entity in neuroanesthetic practice. However, in the past few years, owing to the development of more advanced techniques, drugs and the prolific use of ultrasound guidance, the unrecognised potential of these modalities have been highlighted. These techniques confer the advantages of reduced requirements for local anesthetics, improved hemodynamic stability in the intraoperative period, better pain score postoperatively and reduced analgesic requirements in the postoperative period. Reduced analgesic requirement translates into lesser side effects associated with analgesic use. Furthermore, the transition from the traditional blind landmark-based techniques to the ultrasound guidance has increased the reliability and the safety profile. In this review, we highlight the commonly practised blocks in the neuroanesthesiologist's armamentarium and describe their characteristics, along with their individual particularities.

Cervical plexus block

Cervical plexus blocks (CPBs) have been used in various head and neck surgeries to provide adequate anesthesia and/or analgesia; however, the block is performed in a narrow space in the region of the neck that contains many sensitive structures, multiple fascial layers, and complicated innervation. Since the intermediate CPB was introduced in addition to superficial and deep CPBs in 2004, there has been some confusion regarding the nomenclature and definition of CPBs, particularly the intermediate CPB. Additionally, as the role of ultrasound in the head and neck region has expanded, CPBs can be performed more safely and accurately under ultrasound guidance. In this review, the authors will describe the methods, including ultrasound-guided techniques, and clinical applications of conventional deep and superficial CPBs; in addition, the authors will discuss the controversial issues regarding intermediate CPBs, including nomenclature and associated potential adverse effects that may often be neglected, focusing on the anatomy of the cervical fascial layers and cervical plexus. Finally, the authors will attempt to refine the classification of CPB methods based on the target compartments, which can be easily identified under ultrasound guidance, with consideration of the effects of each method of CPB.

[Regional anesthesia for carotid surgery : An overview of anatomy, techniques and their clinical relevance]

BACKGROUND

Perioperative care for patients undergoing carotid endarterectomy (CEA) often presents a challenge to the anesthesia provider, as this patient group commonly suffers from a wide range of comorbidities. Although clinical trials could not demonstrate a significant benefit associated with regional anesthesia for outcomes such as insult, cardiac infarction or mortality, many authors concur that regional anesthetic techniques might be preferential in specific patient populations for this type of surgery.

OBJECTIVES

This article aims to present an overview of the currently used techniques for regional anesthesia in CEA, as well as discussing their influence on the perioperative outcome.

MATERIALS AND METHODS

After performing an extensive search of medical databases (Pubmed/Medline) the authors present a narrative analysis and interpretation of recent literature.

RESULTS

Currently there is a clear trend towards ultrasound guided regional anesthesia and away from classic landmark based techniques. The literature seems to support the notion that superior and intermediate cervical blocks are safer and less invasive than deep blocks.

CONCLUSIONS

With regional anesthetic techniques evolving to be more and more complex, the use of ultrasound is becoming increasingly indispensable in the operating theatre. For anesthesiologists with sufficient training and a profound knowledge of the respective anatomy, regional anesthesia seems to be a veritable alternative to general anesthesia for CEA.

Pain Associated with Carotid Artery Surgery Performed under Carotid Plexus Block: Preemptive Analgesic Effect of Ketorolac

Carotid artery surgery (CAS) performed under cervical plexus block is frequently associated with significant intra- and postoperative pain. To evaluate whether preoperative administration of ketorolac may improve analgesia in this type of surgery, 80 patients scheduled for CAS under cervical plexus block were randomly allocated to receive intravenously either 30 mg of ketorolac or placebo 30 minutes before surgery. Verbal rating scale pain scores during surgery and 3 and 6 hours after surgery, the number of patients requiring additional analgesia, and the total analgesic consumption both during and within 6 hours after surgery were significantly lower, whereas the time to first postoperative analgesia was significantly shorter in the ketorolac group than in the control group.

The results of this prospective, randomized, double-blind study show that a single 30 mg dose of ketorolac administered intravenously 30 minutes before surgery reduces intraoperative pain and preempts postoperative pain in patients undergoing CAS under carotid plexus block.

Evaluation of the Analgesic Effect of Bilateral Superficial Cervical Plexus Block for Thyroid Surgery: A Comparison of Presurgical with Postsurgical Block

Bilateral superficial cervical plexus block may help in reduction of postthyroidectomy pain. The aim of this study was to evaluate the influence of bilateral superficial cervical plexus block (BSCB) given either presurgically or postsurgically on analgesia in postthyroidectomy patients. Sixty adult euthyroid patients were randomly allocated to one of the three groups, to receive BSCB either presurgically (group A) or postsurgically (group B). Both of the above groups were compared with parenteral analgesics (group C). Thyroid surgery was performed according to a standardised procedure. Postoperative pain was assessed by visual analog scale (VAS), with 10 being the worst pain and 0 being no pain, when patient was fully awake and extubated (0) and after 1, 2, 4, 8, 12, 18, 24, 36 and 48 h. VAS was assessed at four phases: at rest, neck movements, vocalisation and swallowing. Total use of intraoperative fentanyl was noted. The time for first rescue analgesic was also noted. There was no significant statistical difference amongst three groups as regards demographic data and duration of surgery. Patients given BSCBs (either presurgically or postsurgically) had significant lower VAS at all four phases of pain assessment as compared to group C. The time for first rescue analgesia was the earliest in group C. We concluded that BSCB whether given presurgically or postsurgically significantly reduce pain intensity and opioids requirement in postoperative period after thyroid surgery.

Neurologic Derangement and Regional Cerebral Oxygen Desaturation Associated With Patency of the Circle of Willis During Carotid Endarterectomy

OBJECTIVES

To explore the relationship between the maximal fractional decrease of regional cerebral oxygen saturation (rSO2) in neurologic derangement and the patency of the circle of Willis and contralateral carotid artery stenosis.

DESIGN

A prospective observational study.

SETTINGS

A tertiary-care university hospital

PARTICIPANTS

This study enrolled 307 patients undergoing carotid endarterectomy under regional anesthesia.

INTERVENTIONS

No interventions.

MEASUREMENTS AND MAIN RESULTS

Magnetic resonance angiography and carotid color-duplex ultrasound were performed, and the rSO2 was recorded. The relationship between the maximal fractional decrease of rSO2 from preclamp baseline against shunt insertion and patency of the circle of Willis was analyzed by a 2-way analysis of variance. Receiver operating characteristic analysis of the maximal fractional decrease of rSO2 also was performed to calculate the cut-off value for detecting neurologic derangement. In addition, probability of shunt insertion was estimated by logistic regression. Patency of the circle of Willis did not influence the maximal fractional decrease of rSO2. When both anterior and posterior circulations were nonpatent, the degree of contralateral carotid artery stenosis (Contra) was 54.7%±29.0% versus 40.7%±26.0% in patients with versus without shunting, respectively (p<0.05). The cut-off value of rSO2 for predicting shunt insertion was 25.8%, regardless of the patency of the circle of Willis. Probability of shunt insertion for nonpatent anterior circulation = exp(-2.02+0.02×Contra)/[1+exp(-2.02+0.02×Contra)].

CONCLUSIONS

The rSO2 can be used to predict shunt insertion, regardless of the patency of the circle of Willis. The probability of shunt insertion increased with increasing degree of contralateral carotid artery stenosis in the absence of anterior circulation in the circle of Willis.

Carotid Endarterectomy: A Review

Background:

Since the validation of carotid endarterectomy (CEA) as an effective means of stroke prevention, there has been renewed interest in its best indications and methods, as well as in how it compares to carotid angioplasty and stenting (CAS). This review examines these topics, as well as the investigation of carotid stenosis and the role of auditing and reporting CEAresults.

Investigation:

Brain imaging with CTor MRI should be obtained in patients considered for CEA, in order to document infarction and rule out mass lesions. Carotid investigation begins with ultrasound and, if results agree with subsequent, good-quality MRAor CTangiography, treatment can be planned and catheter angiography avoided. An equally acceptable approach is to proceed directly from ultrasound to catheter angiography, which is still the gold-standard in carotid artery assessment.

Indications:

Appropriate patients for CEA are those symptomatic with transient ischemic attacks or nondisabling stroke due to 70-99% carotid stenosis; the maximum allowable stroke and death rate being 6%. Uncertain candidates for CEA are those with 50 - 69% symptomatic stenosis, and those with asymptomatic stenosis ≥ 60% but, if selected carefully on the basis of additional risk factors (related to both the carotid plaque and certain patient characteristics), some will benefit from surgery. Asymptomatic patients will only benefit if surgery can be provided with exceptionally low major complication rates (3% or less). Inappropriate patients are those with less than 50% symptomatic or 60% asymptomatic stenosis, and those with unstable medical or neurological conditions.

Techniques:

Carotid endarterectomy can be performed with either regional or general anaesthesia and, for the latter, there are a number of monitoring techniques available to assess cerebral perfusion during carotid cross-clamping. While monitoring cannot be considered mandatory and no single monitoring technique has emerged as being clearly superior, EEG is most commonly used. “Eversion” endarterectomy is a variation in surgical technique, and there is some evidence that more widely practiced patch closure may reduce the acute risk of operative stroke and the longer-term risk of recurrent stenosis.

Carotid angioplasty and stenting:

Experience with this endovascular and less invasive procedure grows, and its technology continues to evolve. Some experienced therapists have reported excellent results in case series and a number of randomized trials are now underway comparing CAS to CEA. However, at this time it is premature to incorporate CAS into routine practice replacing CEA.

Auditing:

It has been shown that auditing of CEA indications and results with regular feed-back to the operating surgeons can significantly improve the performance of this operation. Carotid endarterectomy auditing is recommended on both local and regional levels.

Regional anesthesia for vascular surgery

Patients presenting for vascular surgery present a challenge to anesthesiologists because of their severe systemic comorbidities. Regional anesthesia has been used as a primary anesthetic technique for many vascular procedures to avoid the cardiovascular and pulmonary perturbations associated with general anesthesia. In this article the use of regional anesthesia for carotid endarterectomy, open and endovascular abdominal aortic aneurysm repair, infrainguinal arterial bypass, lower extremity amputation, and arteriovenous fistula formation is described. A focus is placed on reviewing the literature comparing anesthetic techniques, with brief descriptions of the techniques themselves.

Regional anaesthesia for carotid endarterectomy

Summary Regional anaesthesia is a popular choice for patients undergoing carotid endarterectomy (CEA). Neurological function is easily assessed during carotid cross-clamping; haemodynamic control is predictable; and hospital stay is consistently shorter compared with general anaesthesia (GA). Despite these purported benefits, mortality and stroke rates associated with CEA remain around 5% for both regional anaesthesia and GA. Regional anaesthetic techniques for CEA have improved with improved methods of location of peripheral nerves including nerve stimulators and ultrasound together with a modification in the classification of cervical plexus blocks. There have also been improvements in local anaesthetic, sedative, and arterial pressure-controlling drugs in patients undergoing CEA, together with advances in the management of patients who develop neurological deficit after carotid cross-clamping. In the UK, published national guidelines now require the time between the patient's presenting neurological event and definitive treatment to 1 week or less. This has implications for the ability of vascular centres to provide specialized vascular anaesthetists familiar with regional anaesthetic techniques for CEA. Providing effective regional anaesthesia for CEA is an important component in the armamentarium of techniques for the vascular anaesthetist in 2014.

Regional anaesthesia techniques for carotid surgery: the state of art

PURPOSE

This review will analyse some aspects of regional anaesthesia (RA) for carotid endarterectomy (CEA), a surgical procedure which requires a strict monitoring of patient's status. RA remains an important tool for the anaesthesiologist. Some debates remain about type and definition of regional anaesthesia, efficacy and safety of the different cervical block techniques, the right dose, concentration and volume of local anaesthetic, the use of adjuvants, the new perspectives: ultrasonography, the future directions.

METHODS

A literature search was performed for journal articles in English language in the PubMed Embase and in The Cochrane Library database, from January 2000 to December 2013. The electronic search strategy contained the following medical subject headings and free text terms: local anaesthesia versus general anaesthesia for endarterectomy, superficial and deep cervical block, complications of cervical nerve block, ultrasound guidance of superficial and deep cervical plexus block.

CONCLUSIONS

The gold standard for RA will be achieved after overcoming a number of limitations by a more extensive use of ultrasonography, by combining general and regional anaesthesia, including conscious anaesthesia, by defining the appropriate volume, concentration and dosage of local agents and by addition of adjuvants.

Combination of high-resolution ultrasound-guided perivascular regional anesthesia of the internal carotid artery and intermediate cervical plexus block for carotid surgery

All previously documented regional anesthesia procedures for carotid artery surgery routinely require additional local infiltration or systemic supplementation with opioids to achieve satisfactory analgesia because of the complex innervation of the surgical site. Here, we report a reliable ultrasound-guided anesthesia method for carotid artery surgery. High-resolution ultrasound-guided regional anesthesia using a 12.5-MHz linear ultrasound transducer was performed in 34 patients undergoing carotid endarterectomy. Anesthesia consisted of perivascular regional anesthesia of the internal carotid artery and intermediate cervical plexus block. The internal carotid artery and the nerves of the superficial cervical plexus were identified, and a needle was placed dorsal to the internal carotid artery and directed cranially to the carotid bifurcation under ultrasound visualization. After careful aspiration, local anesthetic was spread around the internal carotid artery and the carotid bifurcation. In the second step, local anesthetic was injected below the sternocleidomastoid muscle along the previously identified nerves of the intermediate cervical plexus. The necessity for intra-operative supplementation and the conversion rate to general anesthesia were recorded. Ultrasonic visualization of the region of interest was possible in all cases. Needle direction was successful in all cases. Three to five milliliters of 0.5% ropivacaine produced satisfactory spread around the carotid bifurcation. For intermediate cervical plexus block, 10 to 20 mL of 0.5% ropivacaine produced sufficient intra-operative analgesia. Conversion to general anesthesia because of an incomplete block was not necessary. Five cases required additional local infiltration with 1% prilocaine (2-6 mL) by the surgeon. Visualization with high-resolution ultrasound yields safe and accurate performance of the block. Because of the low rate of intra-operative supplementation, we conclude that the described ultrasound-guided perivascular anesthesia technique is effective for carotid artery surgery.

Ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in oral and maxillofacial surgery

OBJECTIVES

We examined the application of an ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in patients undergoing oral and maxillofacial surgery.

METHODS

A total of 19 patients receiving ultrasound-guided combined intermediate and deep cervical plexus anaesthesia followed by neck surgery were examined prospectively. The sternocleidomastoid and the levator of the scapula muscles as well as the cervical transverse processes were used as easily depicted ultrasound landmarks for the injection of local anaesthetics. Under ultrasound guidance, a needle was advanced in the fascial band between the sternocleidomastoid and the levator of the scapula muscles and 15 ml of ropivacaine 0.75% was injected. Afterwards, the needle was advanced between the levator of the scapula and the hyperechoic contour of the cervical transverse processes and a further 15 ml of ropivacaine 0.75% was injected. The sensory block of the cervical nerve plexus, the analgesic efficacy of the block within 24 h after injection and potential block-related complications were assessed.

RESULTS

All patients showed a complete cervical plexus nerve block. No patient required analgesics within the first 24 h after anaesthesia. Two cases of blood aspiration were recorded. No further cervical plexus block-related complications were observed.

CONCLUSIONS

Ultrasound-guided combined intermediate and deep cervical plexus block is a feasible, effective and safe method for oral and maxillofacial surgical procedures.

Comparison of intermediate vs subcutaneous cervical plexus block for carotid endarterectomy

BACKGROUND

Carotid endarterectomy surgery can be performed under regional anaesthesia alone or under general anaesthesia. However, there are several types of regional block available and reported complication rates after superficial cervical plexus blocks are significantly lower than deep blocks. It is not known if subcutaneous and intermediate blocks are equally effective, although anatomical evidence suggests that the latter (where the injectate diffuses below the deep cervical fascia) might provide superior quality of intraoperative anaesthesia.

METHODS

Forty-four patients were randomized to receive either subcutaneous or intermediate cervical plexus blocks for carotid endarterectomy. The primary endpoint was supplemental lidocaine requirement during surgery. Secondary outcome measures included: total amount of fentanyl administered during surgery, recall of pain scores during surgery, complications, and patient and surgeon satisfaction.

RESULTS

There was no statistically significant difference for median (range) lidocaine supplementation between the subcutaneous and intermediate groups 65 (20-170) mg vs. 85 (30-345) mg, respectively; P=0.31. There were no statistical differences in the secondary outcome measures and no major complications during the study.

CONCLUSIONS

Intermediate and subcutaneous cervical plexus blocks are equally effective for carotid endarterectomy. This study adds to the body of evidence supporting the safe use of superficial blocks for this type of surgery.

A randomized comparison between ultrasound-guided and landmark-based superficial cervical plexus block

BACKGROUND

This prospective, randomized, observer-blinded study compared ultrasound guidance and the conventional landmark-based technique for superficial cervical plexus blockade.

METHODS

Forty patients were randomly allocated to receive a block of the superficial cervical plexus using ultrasound guidance (n = 20) or the traditional landmark-based technique (n = 20). The main outcome, success, was defined as the absence of cold sensation for all 4 branches of the superficial cervical plexus at 15 mins. A blinded observer recorded success rate, onset time, block-related pain scores, and the incidence of complications. Performance time and the number of needle passes were also recorded during the performance of the block. Total anesthesia-related time was defined as the sum of performance and onset times.

RESULTS

Success rate (80%-85%) was similar between the 2 groups. Performance time was slightly longer with ultrasonography (119 versus 61 sec, P < 0.001); however, no differences in onset and total anesthesia-related times were found. There were also no differences in the number of passes and procedural discomfort.

CONCLUSIONS

Ultrasound guidance does not increase the success rate of superficial cervical plexus block compared with a landmark-based technique. Additional confirmatory trials are required.

[Anesthesia for carotid endarterectomy: a review]

Cardiovascular diseases are associated with high rates of morbidity and mortality. Carotid artery stenosis causes between 20% and 25% of ischemic strokes, especially when an embolism is the underlying cause. Carotid endarterectomy is the treatment of choice when stenosis exceeds 60%. It is important to have an understanding of how to manage perioperative factors that can decrease the risk of stroke, infarction, and death. In contrast to the findings of earlier meta-analyses, the recent GALA trial of general versus local anesthesia concluded that the rates of stroke, myocardial infarction, and mortality during or soon after surgery are similar for both types of anesthesia.

The addition of fentanyl to local anesthetics affects the quality and duration of cervical plexus block: a randomized, controlled trial

BACKGROUND

Cervical plexus block is frequently associated with unsatisfactory sensory blockade. In this randomized, double-blind, placebo-controlled trial, we examined whether the addition of fentanyl to local anesthetics improves the quality of cervical plexus block in patients undergoing carotid endarterectomy (CEA).

METHODS

Seventy-seven consecutive adult patients scheduled for elective CEA were randomized to receive either fentanyl 1 mL (50 microg) or saline placebo 1 mL in a mixture of 10 mL bupivacaine 0.5% and 4 mL lidocaine 2% for deep cervical plexus block. Superficial cervical plexus block was performed using a mixture of 10 mL bupivacaine 0.5% and 5 mL lidocaine 2%. Pain was assessed using the verbal rating scale (0-10; 0 = no pain, 10 = worst pain imaginable), and propofol in 20-mg IV bolus doses was given to patients reporting verbal rating scale >3 during the procedure. Rescue medication consumption during surgery and analgesia requirements over the next 24 hours, as well as onset of sensory blockade, were recorded. A P value <0.05 was regarded as statistically significant.

RESULTS

Fewer patients in the fentanyl group (4 of 38, 10.5%) required propofol compared with the placebo group (26 of 39, 66.7%; P < 0.001). In comparison with the placebo group, the fentanyl group consumed less propofol (median 0 [0-60] vs 60 [0-160] mg, respectively; P < 0.001), required postoperative analgesia less frequently (22 of 38 patients, 57.9% vs 35 of 39 patients, 89.7%, respectively; P = 0.002), and requested the first analgesic after surgery later (median 5.8 [1.9-15.6] vs 3.1 [1.0-11.7] hours, respectively; P < 0.001), whereas the onset time of sensory blockade was similar in both groups (median 12 [9-18] vs 15 [9-18] minutes, respectively; P = 0.18).

CONCLUSIONS

The addition of fentanyl to local anesthetics improved the quality and prolonged the duration of cervical plexus block in patients undergoing CEA.

Wound infiltration for surgery

Wound infiltration with local anaesthetics is a simple, effective and inexpensive means of providing good analgesia for a variety of surgical procedures without any major side-effects. In particular, local anaesthetic toxicity, wound infection and healing do not appear to be major considerations. The purpose of this review is to outline the existing literature on a procedure-specific basis and to encourage a more widespread acceptance of the technique, ensuring that all layers are infiltrated in a controlled and meticulous manner.

Pharmacokinetics of levobupivacaine 0.5% after superficial or combined (deep and superficial) cervical plexus block in patients undergoing minimally invasive parathyroidectomy

STUDY OBJECTIVE

To evaluate the pharmacokinetic profile of 0.35 mL/kg of 0.5% levobupivacaine during superficial and combined (deep and superficial) cervical plexus block (CPB) in patients undergoing minimally invasive parathyroidectomy.

DESIGN

Prospective randomized study.

SETTING

Operating theater of a university hospital.

PATIENTS

12 ASA physical status II and III patients (11 women and 1 man), scheduled for minimally invasive parathyroidectomy.

INTERVENTIONS

Seven and 5 patients were randomly assigned to receive either superficial or combined CPB, respectively. The superficial CPB was performed with an injection of 0.35 mL/kg of 0.5% levobupivacaine subcutaneously along the posterior border of the sternocleidomastoid muscle and deeper on its medial surface. The combined CPB was initiated by the deep block at the C3 level vertebra by injecting 0.2 mL/kg of 0.5% levobupivacaine, followed by the superficial block with an injection of the remaining 0.15 mL/kg. After completion of the block, venous blood was sampled at the intervals of 5, 10, 15, 20, 30, 45, and 60 minutes.

MEASUREMENTS AND MAIN RESULTS

Venous plasma concentrations were measured using gas chromatography-mass spectroscopy. Mean +/- SD of maximal concentrations of levobupivacaine was 0.58 +/- 0.41 mg/L in group superficial and 0.52 +/- 0.28 mg/L in group combined (P = 0.71). The median (range) time required to reach the maximal concentrations was 30 minutes (20-30 min) in group superficial and 20 minutes (15-30 min) in group combined (P = 0.45). The areas under the drug concentration/time curve (AUC(10-60)) were also similar in both groups. No signs of central nervous system or cardiovascular toxicity or other untoward events were observed in any patient.

CONCLUSION

With the given dose regimen, levobupivacaine plasma concentrations were within safe ranges.

A prospective, randomized comparison between combined (deep and superficial) and superficial cervical plexus block with levobupivacaine for minimally invasive parathyroidectomy

BACKGROUND

Minimally invasive parathyroidectomy (MIP) can be performed under cervical plexus block (CPB). Superficial CPB has been reported to be easier to perform with similar efficacy and less anesthesia-related complications than combined deep and superficial CPB. In this study, we compared the efficacy of superficial and combined (deep and superficial) CPB in patients undergoing MIP.

METHODS

Forty-two patients with primary hyperparathyroidism due to a solitary adenoma were randomized to receive either a superficial (group superficial, n = 20) or a combined deep and superficial CPB (group combined, n = 22) using 0.35 mL/kg of 0.5% levobupivacaine. The primary end-point was the amount of supplemental fentanyl required to complete surgery.

RESULTS

There were no differences in onset of block, pain scores during surgery, or time to first analgesic request between groups. Fentanyl consumption was similar in both groups, i.e., 50 (0-200) microg in group superficial and 50 (0-100) microg in group combined (P = 0.60). Six patients [1 in group superficial (5%) and 5 in group combined (22.7%)] were converted to general anesthesia for surgically required bilateral neck dissection (P = 0.18). General anesthesia for block failure was reported in three superficial (15%) and two combined group patients (9%) (P = 0.99). In group combined, only one patient (4.5%) showed diaphragmatic paresis after the block (P = 0.99).

CONCLUSION

Superficial CPB is an alternative to combined block for MIP.

Regional anaesthesia for carotid endarterectomy: an audit over 10 years

BACKGROUND

The aim of this retrospective study was to compare the failure rates and the frequency of anaesthesia-related complications of two different methods of regional anaesthesia used for carotid endarterectomy--cervical epidural (CE) anaesthesia and cervical plexus block (CPB).

METHODS

The study included 1828 carotid endarterectomies performed in 1455 patients between 1996 and 2006. A combination of deep and superficial CPB was used for 1166 procedures, whereas in 662 cases surgery was performed under CE anaesthesia.

RESULTS

The failure rate of CPB was 3% compared with 6.9% for CE anaesthesia (P < 0.0001). The reasons for failure of the anaesthetic techniques were (1) technical failure, (2) insufficient analgesia, (3) non-compliant patients, and (4) anaesthetic complications. The incidence of complications resulting from CE anaesthesia was significantly higher than with CPB; life-threatening complications--2% compared with 0.3% (P < 0.0001); other anaesthesia-related complications 5.7 vs 4.7%. Serious complications included inadvertant injection into the subarachnoid space or vertebral artery. The frequency of shunt insertion, perioperative stroke, and death from any cause was similar in both groups of patients.

CONCLUSIONS

Both methods of regional anaesthesia are acceptable for carotid artery surgery. CPB is associated with a significantly lower frequency of anaesthesia-related complications and should therefore be considered the anaesthetic of choice. CE anaesthesia should not be performed except in extenuating circumstances such as variant anatomy or the requirement for more extensive surgery.

Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications †

Carotid endarterectomy is commonly conducted under regional (deep, superficial, intermediate, or combined) cervical plexus block, but it is not known if complication rates differ. We conducted a systematic review of published papers to assess the complication rate associated with superficial (or intermediate) and deep (or combined deep plus superficial/intermediate). The null hypothesis was that complication rates were equal. Complications of interest were: (1) serious complications related to the placement of block, (2) incidence of conversion to general anaesthesia, and (3) serious systemic complications of the surgical-anaesthetic process. We retrieved 69 papers describing a total of 7558 deep/combined blocks and 2533 superficial/intermediate blocks. Deep/combined block was associated with a higher serious complication rate related to the injecting needle when compared with the superficial/intermediate block (odds ratio 2.13, P = 0.006). The conversion rate to general anaesthesia was also higher with deep/combined block (odds ratio 5.15, P < 0.0001), but there was an equivalent incidence of other systemic serious complications (odds ratio 1.13, P = 0.273; NS). We conclude that superficial/intermediate block is safer than any method that employs a deep injection. The higher rate of conversion to general anaesthesia with the deep/combined block may have been influenced by the higher incidence of direct complications, but may also suggest that the superficial/combined block provides better analgesia during surgery.