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ANALGESIA

A Prospective, Randomized Comparison Between Combined (Deep and Superficial) and Superficial Cervical Plexus Block with Levobupivacaine for Minimally Invasive Parathyroidectomy

Tatjana Stopar Pintaric, MD, MSc^*, Marko Hocevar, MD, PhD, Simona Jereb, MD, Andrea Casati, MD, and Vesna Novak Jankovic, MD, PhD^||

From the Departments of *Anaesthesiology, Surgery, Radiology, Institute of Oncology, Ljubljana, Slovenia; Department of Anaesthesiology, University of Parma, Parma, Italy; and ||Department of Anaesthesiology and Intensive Therapy, Clinical Center Ljubljana, Ljubljana, Slovenia.

Address correspondence and reprint requests to Dr. Tatjana Stopar Pintaric, Department of Anesthesiology, Institute of Oncology, Zaloska 2, 1000 Ljubljana, Slovenia. Address e-mail to tstopar{at}onko-i.si.

Abstract

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) µg in group superficial and 50 (0–100) µg 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.

The recent improvement in preoperative and intraoperative localization methods for isolated adenoma of the parathyroid gland has progressively changed the surgical approach in patients with primary hyperparathyroidism (PH) from conventional bilateral neck exploration to minimally invasive surgical procedures, which can be performed with cervical plexus block (CPB) due to the limited unilateral incision (1).

Several investigations have already demonstrated a successful use of CPB for thyroid and parathyroid surgery (2–5), but only two have evaluated this technique for minimally invasive parathyroidectomy (MIP) (1,6). At our institution, radio-guided MIP is the standard of care for patients with PH due to a single parathyroid adenoma, and is mostly performed under CPB.

Superficial CPB is reported to be easier to perform than combined deep and superficial CPB with similar efficacy and fewer anesthesia-related complications, such as diaphragmatic dysfunction or inadvertent intravascular, epidural or subarachnoid injection of local anesthetic (7–14). We therefore conducted this prospective, randomized, observer-blinded study to compare the overall anesthetic efficacy, need for intraoperative analgesic supplementation, time to first postoperative analgesic request, patient satisfaction, and complications and side effects of either superficial or combined CPB performed with 0.35 mL/kg of 0.5% levobupivacaine in patients undergoing MIP.

METHODS

With Ethical Committee approval and written informed consent, 42 patients with PH due to a solitary parathyroid adenoma scheduled for elective MIP were prospectively studied. All patients underwent standard preoperative adenoma localization tests using scanning with 99m Technetium MIBI (hexakis 2metoksiisobutil-isonitril) and ultrasonography (Toshiba Diagnostic Ultrasound System SSA-770A Aplio). Patients with coagulation disorders, history of allergy to aminoamide local anesthetic, local sepsis, or diaphragmatic motion abnormality were excluded.

All patients were premedicated 1–2 h before surgery with 7.5 mg of oral midazolam (Dormicum 7.5 mg, Roche, Germany). On arrival into the operating room, an IV catheter was inserted in the forearm, and lactated Ringer’s solution infused IV (3 mL · kg^–1 · h^–1). Standard monitoring was applied including noninvasive arterial blood pressure, one-lead electrocardiography, and pulse oximetry. An oxygen-enriched mixture was delivered through a facemask or a nasal cannula during surgery until discharge from the postanesthesia care unit.

Using a computer-generated sequence of random numbers and sealed envelopes, patients were randomly allocated to receive either a combined deep and superficial CPB (group combined, n = 22) or a superficial CPB (group superficial, n = 20) with 0.35 mL/kg of 0.5% levobupivacaine (Chirocaine, levobupivacaine hydrochloride 5.0 mg/mL, Abbott Laboratories LTD, Slovenija). All blocks were performed by the attending anesthesiologist experienced in this technique. During block placement, patients were lying supine with their heads slightly extended and rotated to the lateral side opposite to the block. The superficial block was administered after local skin infiltration with 2 mL of 2% lidocaine at the midpoint of the posterior border of the sternocleidomastoid (SCM) muscle using a 22-gauge needle, which was followed by an injection of 0.5% levobupivacaine subcutaneously along the posterior border of the muscle in cranial and caudal directions and deeper, on the medial surface of the muscle (beneath the muscle) with the total dosage of 0.35 mL/kg.

The combined CPB was initiated by a deep block using a single injection technique at the C3 vertebral level. After palpating the transverse process (next to the posterior border of SCM muscle) and local skin infiltration with 2 mL of 2% lidocaine, a 24-gauge needle was introduced perpendicularly in a slightly caudal direction until the transverse process was located in the depth of 2–3 cm followed by an injection of 0.2 mL/kg of 0.5% levobupivacaine after negative aspiration for blood and/or cerebrospinal fluid. Superficial CPB was placed by injecting the remaining 0.15 mL/kg of 0.5% levobupivacaine as described above. During block placement and throughout surgery, patients were sedated, if needed, with IV midazolam (Midazolam Torrex 1.0 mg/mL, Torrex Pharma, Vienna, Austria) in 0.5–1 mg aliquots up to a maximal dose of 5 mg.

A blinded observer, not present during block placement, subsequently recorded the onset and extent of sensory block every 5 min until the loss of pinprick sensation in the C2–4 dermatomes. When satisfactory anesthesia was obtained, surgical exploration was performed using standard technique (1). The approach was based on the individual preoperative localization of the parathyroid adenoma. For the upper gland, an incision was made along the anterior border of the SCM muscle. For an anterior lower adenoma, an abbreviated Kocher incision was used. After subcutaneous and muscular layer preparation, the thyroid gland was exposed and a parathyroid adenoma located using a hand-held probe (Navigator GPS System, USSC, USA). If the gland was not found in its typical location, an extended ipsilateral or even a bilateral exploration was performed. The latter required induction of general anesthesia with a laryngeal mask airway placement. All surgical procedures were performed by the same surgeon. The duration of surgery was measured from the first incision to wound closure.

The average degree of pain during surgery was measured using a 10-cm visual analog scale (VAS: 0 = no pain; 10 = worst imaginable pain). If the patient complained of pain/discomfort while the surgeon was trying to locate and/or remove the adenoma (VAS 4), supplemental IV analgesia with 25 µg boluses of fentanyl (Fentanyl Torrex 50 µg/mL, Torrex Pharma) up to a maximum dose of 200 µg was given by the blinded observer. If this proved to be ineffective to complete the surgery, general anesthesia was induced. During block placement and throughout surgery, complications of CPB placement as well as side effects such as nausea, hoarseness, and Horner’s syndrome were also recorded.

At the end of surgery, the patient was transferred to the postanesthesia care unit, where a blinded observer evaluated patient satisfaction with the anesthesia technique using a two-point scale: 1) good (if operated on again in the future, I accept the same anesthesia technique); 2) bad (if operated on again in the future, I would prefer a different anesthesia technique).

Postoperative analgesia consisted of IV metamizole 2.5 mg (Analgin, metamizolum natricum 2.5 mg/5 mL, Alkaloid Skopje, Macedonia) every 12 h if needed, i.e., the first analgesic administration was given at patient request (VAS 4 cm), the time of which was also recorded.

The occurrence of phrenic nerve block was assessed by measuring the ipsilateral hemidiaphragmatic excursion before CPB placement and immediately after the operation using 2D mode real-time ultrasonography with 1.9–6.0 MHz convex probe (Aplio XV; Toshiba, Otawara, Japan), placed on the thoracic wall parallel to the middle axillary line between the 8th and 12th intercostal spaces (15). The extent of the hemidiaphragmatic excursion was assessed during normal breathing and maximal inspiratory sniff maneuver and defined as the difference between the diaphragm positions, respectively, recorded at functional residual capacity and at the end of inspiration. The excursion distance was expressed in centimeters. Normal inspiratory caudad diaphragmatic excursion was designated as positive motion and paradoxical cephalad (paretic) excursion as negative motion.

The null hypothesis under test was that the efficacy of superficial CPB alone for MIP should not differ from that provided by combined superficial and deep CPB. Accordingly, the primary outcome measure for this study was the amount of supplemental fentanyl required to complete surgery. We considered as clinically significant a difference of intraoperative fentanyl consumption 50 µg between the two groups. From our previous pilot study, we estimated a standard deviation (sd) of supplemental fentanyl consumption of ±50 µg. Based on these assumptions, 21 patients per group were needed to detect the above-defined treatment effect accepting a two-tailed -error of 5% and a ß-error of 10%, with a power of 90% (16).

Statistical analysis was performed using a statistical software package (SigmaStat 3.1). Normal distribution of data was first evaluated with the Kolmogorov–Smirnov test. Continuous variables were then analyzed using the Student’s t-test or Mann–Whitney U-test according to data distribution. Categorical variables were analyzed with the contingency table analysis and Fisher’s exact test. P 5% was considered significant. Continuous variables are presented as mean (±sd) or median (range), whereas categorical variables are presented as count (%).

RESULTS

No differences in age, height, weight, gender, ASA physical status distribution, and duration of surgery were reported between the two groups (Table 1).

No differences in the onset time of surgical block, pain scores during surgery, time for the first postoperative analgesic request, and patient satisfaction were observed between the two groups (Table 2).

The median (range) fentanyl consumption was 50 (0–200) µg in group superficial and 50 (0–100) µg in group combined (P = 0.60), with a 95% CI for the between group difference of –34 to 29 mg, whereas midazolam consumption was 2.0 (0–4.0) mg in group superficial and 2.0 (0–4.0) mg in group combined (P = 0.98), with a 95% CI for the between group difference of –1 to 1 mg.

In six patients [1 in group superficial (5%) and 5 in group combined (22.7%)], it was not possible to locate the adenoma, which required bilateral neck exploration (P = 0.18). In all these patients, general anesthesia was given with laryngeal mask insertion. General anesthesia due to block failure despite maximum fentanyl consumption was reported in three patients in the superficial group (15%) and two in the combined group (9%) (P = 0.99).

No differences in hemodynamic variables were observed between the two groups. No major complications or significant differences in the occurrence of minor side effects were reported in the two groups (Table 3).

For surgical reasons, two patients who had undergone a bilateral neck dissection were admitted to the hospital overnight.

DISCUSSION

The main finding of this investigation is that adding deep CPB to the superficial does not increase the efficacy and success rate of CPB in patients undergoing MIP while providing similar onset time of surgical block, similar consumption of intraoperative rescue analgesics, and similar patient satisfaction. Similar findings have been reported in previous investigations comparing superficial with either deep or combined deep and superficial CPB for carotid endarterectomy (12–14).

The lack of clinical differences between placing either a superficial block alone or a combined deep and superficial CPB is supported by recent anatomical findings. Nash et al. (17) reported that the investing layer of the deep cervical fascia (DCF) in the anterior triangle of the neck does not exist. They also demonstrated that the fatty and connective tissues around nerves and vessels in the neck provide a direct communication between the subcutaneous tissue and the prevertebral layer of the DCF. Moreover, Pandit et al. (18) demonstrated that the dye injected above the prevertebral layer of the DCF penetrates through the "pores" where the nerves pierce the fascia, ending in the deep cervical space. The deep and the superficial spaces thus virtually act as a single space, which supports the present findings of similar clinical effectiveness.

It has been demonstrated that combined deep and superficial CPB is associated with phrenic nerve block and hemidiaphragmatic paresis in up to 61% of patients (7,8). In the present investigation, the incidence of ipsilateral hemidiaphragm paresis was considerably lower. This can be related to a number of factors. First, the volume of local anesthetic used by Castresana et al. (7) for CPB (24–28 mL of 1% mepivacaine) and, similarly, by Emery et al. (8) the deep CPB (22 ± 4 mL of 1.5% lidocaine with adrenaline) were substantially higher than the volumes injected for deep block in our study, i.e., 13 ± 2 mL. Second, the phrenic nerve roots may have been affected more extensively by using the three-injection technique (C2–4) when compared with the single-injection technique applied in our study (8). Further factors influencing the outcome might have been the variations in the innervation of the diaphragm and the difference in sensitivity of the techniques used to evaluate the diaphragm motion (ultrasonography versus fluoroscopy).

Recurrent laryngeal nerve palsy secondary to the diffusion of local anesthetic has been well described after deep CPB (19). In our investigation, three patients reported vocal cord dysfunction with hoarseness. Although transitory in nature, this side effect may have serious implications in patients with asymptomatic contralateral vocal cord paralysis from a previous neck surgery (20), suggesting that a routine preoperative assessment of vocal cord function by indirect laryngoscopy in patients with either a history of vocal cord dysfunction or previous neck surgery should be performed to avoid the risk of a temporary intraoperative respiratory obstruction (21).

The number of patients requiring general anesthesia was higher than that reported by Carling et al. in a larger population (26% vs 10%) (6). However, in more than half of our patients, general anesthesia was administered for surgical reasons, since neither scintigraphy nor ultrasound allowed accurate preoperative adenoma localization, thus requiring bilateral neck exploration. On the contrary, in patients who underwent MIP, the adenoma was preoperatively localized with precision.

In conclusion, results of this prospective, randomized, observer-blinded study showed that superficial CPB with 0.35 mL/kg of 0.5% levobupivacaine provided the same anesthetic efficacy as combined deep and superficial CPB for MIP, with the potential advantage of less anesthesia-related complications.

Footnotes

Accepted for publication June 21, 2007.

In memoriam Andrea Casati (1966–2007).

REFERENCES

1. Chen H, Sokoll LJ, Udelsman R. Outpatient minimally invasive parathyroidectomy: a combination of sestamibi-SPECT localization, cervical block anesthesia, and intraoperative parathyroid hormone assay. Surgery 1999;126:1016–22[Web of Science][Medline]
2. Lo Gerfo P. Loco-regional anesthesia for thyroidectomy: evaluation as an outpatient procedure. Surgery 1998;124:975–9[Web of Science][Medline]
3. Ditkoff BA, Chabot J, Feind C, Lo Gerfo P. Parathyroid surgery using monitored anesthesia care as an alternative to general anesthesia. Am J Surg 1996;172:698–700[Web of Science][Medline]
4. Lo Gerfo P. Bilateral neck exploration for parathyroidectomy under local anesthesia: a viable technique for patients with coexisting thyroid disease with or without sestamibi scanning. Surgery 1999;26:1011–5
5. Kulkarni RS, Braverman LE, Patwardhan NA. Bilateral cervical plexus block for thyroidectomy and parathyroidectomy in healthy and high risk patients. J Endocrinol Invest 1996;19:714–8[Web of Science][Medline]
6. Carling T, Donovan P, Rinder C, Udelsman R. Minimally invasive parathyroidectomy using cervical block. Arch Surg 2006;141:401–4[Abstract/Free Full Text]
7. Castresana MR, Masters RD, Castasena EJ, Stefansson S, Shaker IJ, Newman WH. Incidence and clinical significance of hemidiaphragmatic paresis in patients undergoing carotid endarterectomy during cervical plexus block anesthesia. J Neurosurg Anesthesiol 1994;6:21–3[Web of Science][Medline]
8. Emery G, Handley G, Davies MJ, Mooney PH. Incidence of phrenic nerve block and hypercapnia in patients undergoing carotid endarterectomy under cervical plexus block. Anaesth Intensive Care 1998;26:377–81[Web of Science][Medline]
9. Carling A, Simmonds M. Complications from regional anaesthesia for carotid endarterectomy. Br J Anaesth 2000;84:797–800[Abstract/Free Full Text]
10. Stoneham MD, Wakefield TW. Acute respiratory distress following deep cervical plexus block. J Cardiothorac Vasc Anesth 1998;12:197–8[Web of Science][Medline]
11. Davies MJ, Silbert BS, Scott DA, Cook RJ, Mooney PH, Blyth C. Superficial and deep cervical plexus block for carotid artery surgery: a prospective study of 1000 blocks. Reg Anesth 1997;22:442–6[Web of Science][Medline]
12. Pandit JJ, Bree S, Dillon P, Elcock D, McLaren ID, Crider B. A comparison of superficial versus combined (superficial and deep) cervical plexus block for carotid endarterectomy: a prospective, randomized study. Anesth Analg 2000;91:781–6[Abstract/Free Full Text]
13. Stonham MD, Doyle AR, Knighton JD, Dorje P, Stanley JC. Prospective, randomised comparison of deep or superficial cervical plexus block for carotid endarterectomy surgery. Anesthesiology 1998;89:907–12[Web of Science][Medline]
14. De Sousa AA, Filho MA, Faglione W Jr, Carvalho GT. Superficial vs combined cervical plexus block for carotid endarterectomy: a prospective, randomized study. Surg Neurol 2005;63:S22–5[Medline]
15. Urmey WF, Talts KH, Sharrock NE. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography. Anesth Analg 1991;72:498–503[Abstract/Free Full Text]
16. Browner WS, Black D, Newman B, Hulley SB. Estimating sample size and power. In: Hulley SB, Cummings SR, eds. Designing clinical research—an epidemiologic approach. Baltimore: Williams & Wilkins, 1988;139–50
17. Nash L, Nicholson HD, Yhang M. Does the investing layer of the deep cervical fascia exist? Anesthesiology 2005;103:962–8[Web of Science][Medline]
18. Pandit JJ, Dutta D, Morris JF. Spread of injectate with superficial cervical plexus block in humans: an anatomical study. Br J Anaesth 2003;91:733–5[Abstract/Free Full Text]
19. Harris RJD, Benveniste G. Recurrent laryngeal nerve blockade in patients undergoing carotid endarterectomy under cervical plexus block. Anaesth Intensive Care 2000;28:431–3[Web of Science][Medline]
20. Kwok AOK, Silbert BS, Allen KJ, Bray PJ, Vidovich J. Bilateral vocal cord palsy during carotid endarterectomy under cervical plexus block. Anaesth Analg 2006;102:376–7[Abstract/Free Full Text]
21. Curran AJ, Smyth D, Sheehan SJ, Joyce W, Hayes DB, Walsh MA. Recurrent laryngeal nerve dysfunction following carotid endarterectomy. J R Coll Surg Edinb 1997;42:168–70[Medline]

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