The spread of sensory blockade after epidural injection of a specific dose of local anesthetic (LA) differs considerably among individuals, and the factors affecting this distribution remain the subject of debate. Based on the results of recent investigations regarding the distribution of epidural neural blockade, specifically for thoracic epidural anesthesia, we noted that the total mass of LA appears to be the most important factor in determining the extent of sensory, sympathetic, and motor neural blockade, whereas the site of epidural needle/catheter placement governs the pattern of distribution of blockade relative to the injection site. Age may be positively correlated with the spread of sensory blockade, and the evidence is somewhat stronger for thoracic than for lumbar epidural anesthesia. Other patient characteristics and technical details, such as patient position, and mode and speed of injection, exert only a small effect on the distribution of sensory blockade, or their effects are equivocal. However, combinations of several patient and technical factors may aid in predicting LA dose requirements. Based on these results, we have also formulated suggested epidural insertion sites that may optimize both analgesia and sympathicolysis for various surgical indications.

Authors: Al-Rawi, Omar Y. FRCA *; Pennefather, Stephen H. MRCP, FRCA *; Page, Richard D. FRCS +; Dave, Ishani FRCA *; Russell, Glen N. FRCA *

Institution From the Departments of *Anaesthesia and +Thoracic Surgery, Cardiothoracic Centre, Liverpool, United Kingdom.

Title The Effect of Thoracic Epidural Bupivacaine and an Intravenous Adrenaline Infusion on Gastric Tube Blood Flow During Esophagectomy.[Report]

Source Anesthesia & Analgesia. 106(3):884-887, March 2008.

Abstract BACKGROUND: Gastric tube necrosis is a major cause of anastomotic leak after esophagectomy. A correlation has been shown between reduced flux at the anastomotic end of the gastric tube and anastomotic leaks.

METHODS: We prospectively studied the effect of intraoperative thoracic epidural bupivacaine and subsequent adrenaline infusion on hemodynamics and flux in the gastric tube.

RESULTS: Administering the epidural bolus significantly decreased flux at the anastomotic end of the gastric tube (P < 0.01). Gastric flux was returned to baseline by an adrenaline infusion. CONCLUSIONS: The administration of a thoracic epidural bolus may decrease flux at the anastomotic end of the gastric tube.

Background: The oesophagectomy procedure includes the formation of a gastric tube to re-establish the continuity of the gastrointestinal tract. The effect of thoracic epidural analgesia (TEA) on gastric mucosal blood flow (GMBF) remains unknown in clinical practice. The aim of this prospective observational study was to assess the microcirculatory changes induced by TEA in the early post-operative course.

Methods: Eighteen consecutive patients who underwent radical oesophagectomy with en-bloc resection and two-field lymphadenectomy for oesophageal cancer, and benefited from TEA during the post-operative course, were studied prospectively, and compared with nine patients who declined the use of TEA in the same period (control group). GMBF was measured using a laser Doppler flowmeter in three consecutive time periods (before and after 1 and 18 h of TEA infusion). Post-operative monitoring also included the measurement of arterial pressure, cardiac output, gas exchange and intrathoracic blood volume index.

Results: After the first and 18th hour of infusion, TEA induced an increase in GMBF compared with baseline and the control group. The mean arterial pressure and intrathoracic blood volume index decreased after the first hour of TEA infusion with no influence on the cardiac index.

Conclusions: This clinical study demonstrates that TEA improves the microcirculation of the gastric tube in the early post-oesophagectomy period. The clinical relevance of TEA in this setting should be validated in larger studies focusing on the clinical outcome following oesophagectomy.

Authors: Solak, O.; Metin, M.; Esme, H.; Solak, O.; Yaman, M.; Pekcolaklar, A.; Gurses, A.; Kavuncu, V.
Eur J Cardio-Thorac Surg 32: 9-12, 2007
Keywords: Chronic post-thoracotomy pain; Neuropathic pain; Gabapentin; Wound pain
Abstract (English): Background: Chronic post-thoracotomy pain (CPTP) consists of different types of pain. Some characteristics of CPTP are the same as those of recognized neuropathic pain syndromes. Objective: We aimed to determine the safety and efficacy of gabapentin (GP) in comparison to naproxen sodium (NS) in patients with CPTP. Methods: Forty consecutive patients with CPTP after posterolateral/lateral thoracotomy were prospectively evaluated. Twenty patients were given GP and another 20 were given NS treatment. Visual Analogue Scale (VAS) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scorings were performed pretreatment (day 0) and on the 15th, 30th, 45th and 60th days. Adverse events were questioned. The mean ages were 45.7+/-14.9 and 49.8+/-15.2 years and the mean durations of pain were 3.8+/-0.9 and 3.8+/-1.1 months, respectively. Results: The mean pretreatment VAS scores (VAS0) were 6.4+/-0.6 and 6.8+/-0.6, the mean pretreatment LANSS scores (LANSS0) were 18.85+/-1.6 and 20.75+/-2.6 in GP and NS groups, respectively (p>0.05). Minor adverse events which did not mandate discontinuation of treatment were observed in seven patients (35%) in the GP and in four patients (20%) in the NS group. The number of patients with a VAS score <5 at the latest follow-up (VAS60<5) was 17 (85%) and 3 (15%) in GP and NS groups, respectively (p<0.001). Seventeen patients (85%) in the GP and 0 patients (0%) in the NS group had a LANSS score <12 at the latest follow-up. Conclusion: Gabapentin is safe and effective in the treatment of CPTP with minimal side effects and a high patient compliance. These results should be supported with multidisciplinary studies with larger sample sizes and longer follow-ups.

Objectives: This study was designed to evaluate the effectiveness of low-volume interscalene brachial plexus block for post-thoracotomy ipsilateral shoulder pain and to compare it with nonsteroidal anti-inflammatory drug treatment. Design: Prospective nonblinded study. Setting: University hospital. Participants: Sixty adult patients. Intervention: Patients who underwent elective thoracic surgery under combined epidural and general anesthesia, and after surgery were free of incisional pain but complaining of shoulder pain, were included in the study. They were selected in a sequential manner and placed into 2 groups of 30 patients each. Group 1 had a low-volume interscalene brachial plexus block, using 10 mL of bupivacaine 0.5%. Group 2 had an intramuscular injection of diclofenac sodium, 75 mg. Measurements and Main Results: Pain was measured during their stay in the postanesthesia care unit (PACU) by using a visual analog score (VAS). Opioids were administered when pain relief was incomplete. Pain intensity was re-estimated the next morning and patient satisfaction was scored. VAS was found to be significantly lower in the low-volume interscalene block group than in the diclofenac group at 30 minutes after treatment and when leaving PACU (p < 0.001 for both). Patients in the interscalene block group stayed longer in the PACU (p = 0.019), and significantly fewer required rescue opioids (p = 0.03). There was no significant difference between the groups in patient satisfaction with the pain treatment. Conclusions: The authors concluded that low-volume interscalene brachial plexus block is a superior treatment for post-thoracotomy shoulder pain compared with diclofenac injection, although it requires a slightly longer stay in the PACU. J Cardiothorac Vasc Anesth 21: 554-7, 2007

R. G. Davies1, P. S. Myles1,2,3,* and J. M. Graham4
1Department of Anaesthesia and Pain Management, Alfred Hospital Commercial Road, Melbourne, Victoria 3004, Australia
2Academic Board of Anaesthesia and Perioperative Medicine, Monash University Victoria 3800, Australia
3Centre for Clinical Research Excellence Canberra, Australia
4Department of Anaesthesia, Austin Hospital Heidelberg, Australia

*Corresponding author: Department of Anaesthesia and Pain Management, The Alfred Hospital, PO Box 315, Melbourne, VIC, 3004, Australia. E-mail: p.myles@alfred.org.au

Epidural analgesia is considered by many to be the best method of pain relief after major surgery. It is used routinely in many thoracic surgery centres. Although effective, side-effects include hypotension, urinary retention, incomplete (or failed) block, and, in rare cases, paraplegia. Paravertebral block (PVB) is an alternative technique that may offer comparable analgesic effectiveness and a better side-effect profile. We undertook a systematic review and meta-analysis of all relevant randomized trials comparing PVB with epidural analgesia in thoracic surgery. Data were abstracted and verified by both authors. Studies were tested for heterogeneity, and meta-analyses were done with random effects or fixed effects models. Weighted mean difference (WMD) was used for numerical outcomes and odds ratio (OR) for dichotomous outcomes, both with 95% CI.

We identified 10 trials that had enrolled 520 thoracic surgery patients. All of the trials were small (n<130) and none were blinded. There was no significant difference between PVB and epidural groups for pain scores at 4–8, 24 or 48 h, WMD 0.37 (95% CI: –0.5, 121), 0.05 (–0.6, 0.7), –0.04 (–0.4, 0.3), respectively. Pulmonary complications occurred less often with PVB, OR 0.36 (0.14, 0.92). Urinary retention, OR 0.23 (0.10, 0.51), nausea and vomiting, OR 0.47 (0.24, 0.53), and hypotension, OR 0.23 (0.11, 0.48), were less common with PVB. Rates of failed block were lower in the PVB group, OR 0.28 (0.2, 0.6). PVB and epidural analgesia provide comparable pain relief after thoracic surgery, but PVB has a better side-effect profile and is associated with a reduction in pulmonary complications. PVB can be recommended for major thoracic surgery.

Title: Variability of a Thoracic Paraveretbral Block: Are we ignoring the Endothoracic Fascia?
Authors: Karmakar MK,Chung DC
Journal:Reg Anesth Pain Med 25: 325-7,2000

Letter. The variability which is reported in the spread of local anesthetics in the paravertebral space may depend on whether the injection is superficial or deep to the endothoracic fascia which divides the paravertebral space into two compartments.Due to attachments of this fascia to ribs and the vertebral bodies, injection into the subendothoracic compartment would be expected to spread more easily to other dermatomes and contralaterally. The thinness of this fascia ( 250 um) would make it difficult to identify during either open or percutaneous paravertebral block.

uthors
Richardson J. Sabanathan S. Jones J. Shah RD. Cheema S. Mearns AJ.
Institution
Department of Anaesthetics, Bradford Royal Infirmary, UK.
Title
A prospective, randomized comparison of preoperative and continuous balanced epidural or paravertebral bupivacaine on post-thoracotomy pain, pulmonary function and stress responses.
Source
British Journal of Anaesthesia. 83(3):387-92, 1999 Sep.
Local Messages
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Abstract
Both epidural and paravertebral blocks are effective in controlling post-thoracotomy pain, but comparison of preoperative and balanced techniques, measuring pulmonary function and stress responses, has not been undertaken previously. We studied 100 adult patients, premedicated with morphine and diclofenac, allocated randomly to receive thoracic epidural bupivacaine or thoracic paravertebral bupivacaine as preoperative bolus doses followed by continuous infusions. All patients also received diclofenac and patient-controlled morphine. Significantly lower visual analogue pain scores at rest and on coughing were found in the paravertebral group and patient-controlled morphine requirements were less. Pulmonary function was significantly better preserved in the paravertebral group who had higher oxygen saturations and less postoperative respiratory morbidity. There was a significant increase in plasma concentrations of cortisol from baseline in both the epidural and paravertebral !
groups and in plasma glucose concentrations in the epidural group, but no significant change from baseline in plasma glucose in the paravertebral group. Areas under the plasma concentration vs time curves for cortisol and glucose were significantly lower in the paravertebral groups. Side effects, especially nausea, vomiting and hypotension, were troublesome only in the epidural group. We conclude that with these regimens, paravertebral block was superior to epidural bupivacaine.

Authors
Bimston DN. McGee JP. Liptay MJ. Fry WA.
Institution
Department of Surgery, Evanston Hospital, Ill, USA.
Title
Continuous paravertebral extrapleural infusion for post-thoracotomy pain management.
Source
Surgery. 126(4):650-6; discussion 656-7, 1999 Oct.
Local Messages
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Abstract
BACKGROUND: Continuous thoracic epidural analgesia is considered by many the gold standard for post-thoracotomy pain control but is associated with its own complications. In this study we compare continuous paravertebral extrapleural to epidural infusion for post-thoracotomy pain control. METHODS: In a prospective fashion, 50 patients were randomized to receive either paravertebral or epidural infusion for post-thoracotomy pain control. The anesthesia department placed epidurals, and the operative surgeon placed unilateral paravertebral catheters. Patients were evaluated for analgesic efficacy and postoperative complications. RESULTS: We found that both methods of analgesia provide adequate postoperative pain control. Epidural infusion demonstrated an improved efficacy early in the postoperative course but provided statistically similar analgesia to paravertebral by postoperative day 2. Neither group demonstrated a greater number of pain-related complications. Narcotic-induc!
ed complications such as pruritus, nausea/vomiting, and postural hypotension/mental status changes/respiratory depression were seen with statistically similar frequency in both epidural and paravertebral arms. Urinary retention, however, was noted to be significantly more frequent in patients with epidural catheters. Drug toxicity was not observed with either epidural or paravertebral infusion. CONCLUSIONS: We recommend continuous paravertebral infusion as an improved method of post-thoracotomy analgesia that can be placed and managed by the surgeon.

A previous study suggested that PaO2 during one-lung ventilation (OLV) was decreased when thoracic epidural anesthesia (TEA) was used in combination with general anesthesia compared to general anesthesia alone(1). A recent study suggests that TEA increases PaO2 during OLV(2). The most likely explanation for these opposite conclusions is that TEA has little direct effect on shunt and PaO2 during OLV. The differences are more likely related to changes in cardiac output and PvO2 related to differing anesthetic managment in the two studies. Continue Reading »

There has been a concern that thoracic epidural analgesia with local anesthetics could decrease lung mechanical function due to effects on the chest wall. A recent study shows that analgesic doses of local anesthetics in thoracic epidurals do not cause a reduction of lung mechanics in a group of patients with severe COPD. Continue Reading »