Epidural analgesia is considered the gold standard analgesic technique for postoperative acute pain management after major surgery.1 Although major complications (epidural haematoma and permanent neurological injury) have been widely investigated,2–4 a lack of overview on minor complications and related risk factors was found. Most commonly reported minor complications during thoracic epidural catheter placement include bloody punctures (1.7%), dural perforation (0.8%), paraesthesia (0.5%), malposition (7.1%), disconnection (0.6%) and occlusion (0.4%).2 We investigated the occurrence of minor complications and related risk factors during thoracic epidural catheter placement.
Ethical approval for this study (Protocol INT150-12) was provided by the Independent Ethics Committee of the Fondazione IRCCS Istituto Nazionale dei Tumori of Milan, Italy (chairman Dr Roberto Satolli) on 17 December 2012.
Data concerning patients undergoing thoracic epidural analgesia from November 2008 to December 2012 at our institution were reviewed. All data were retrieved from our electronic prospectively maintained Acute Pain Service database (installed on a handheld device).
All epidural catheters (Polymedic, Temena SARL, Bondy, France or FlexTip Plus; Arrow International, Reading, USA) were inserted, before surgery, with a 17/18-gauge Rodiera or 17-gauge Tuohy needle through the thoracic intervertebral spaces using the loss-of-resistance technique. The correct catheter placement was evaluated with the aspiration test and with the infusion of 3 ml 1% mepivacaine with epinephrine 1 : 200 000 in order to exclude intrathecal or intravascular placement.
Logistic regression was performed to ascertain the effects of risk factors on the likelihood that patients had a minor complication at catheter positioning. We analysed age, sex, BMI, patient's position during puncture (sitting vs. lateral decubitus), needle (Tuohy vs. Rodiera), puncture approach (median vs. lateral), level of thoracic puncture (grouped as follows: high level T3-T7, mid T7-T10, low T10-L1), type of catheter (normal vs. reinforced) and anaesthesiologist (staff anaesthesiologists vs. residents) as risk factors for minor complications at epidural catheter positioning. A P value of less than 0.05 was considered as statistically significant. Data analysis was carried out with IBM SPSS Statistics v.21 (IBM Corporation, Armonk, New York, USA).
We obtained data on 2084 patients, finding 124 placements with minor complications (Table 1), showing an overall incidence of 5.95% [95% confidence interval (95% CI) 4.93 to 6.97)].
To our knowledge, no patients developed neurological sequelae after radicular symptoms or bloody puncture during catheter positioning. No patients developed a clinically evident epidural haematoma after the procedure. When the catheter did not advance in the epidural space, it was successfully positioned at another intervertebral level. Five out of 23 patients (21.7%) suffered postdural puncture headache. Only one patient received a blood-patch treatment immediately after dural puncture and did not develop a headache. Fainting occurred more frequently in younger patients [mean age: 51.9 (95% CI 39.7 to 64.1) vs. 61.2 (95% CI 60.8 to 62.0); P = 0.037]. Logistic regression showed a higher risk of difficult catheter progression in the epidural space during staff anaesthesiologists’ attempts than residents’ efforts (odds ratio 4.37; 95% CI 1.03 to 18.52; P = 0.046). The paramedian puncture approach showed a greater association with intraoperative catheter occlusion than the median one (odds ratio 3.58; 95% CI 1.25 to 10.27; P = 0.017). No other risk factors were found to be significant for minor complications.
We observed a rather high overall incidence of minor complications at thoracic epidural catheter placement (5.95%). Difficult catheter progression in the epidural space was the most common problem encountered (1.3%). This occurred more frequently with staff anaesthesiologists than residents. However, in our opinion, the placement by an experienced anaesthesiologist cannot be considered at all a risk factor for difficult catheter progression, as they often deal with more complicated patients and, moreover, with failed placements by residents. Interestingly, when the epidural catheter did not successfully advance in the epidural space (0.5%), it was positively placed at another intervertebral space.
Bloody puncture occurred less frequently than reported by others (1 vs. 1.75%), although we observed a higher incidence of paraesthesia during catheter insertion (0.8 vs. 0.47%).2 To our knowledge, no patients had permanent neurological injury due to haematoma or radicular damage. Dural perforation and intrathecal catheter placement occurred in 0.9 and 0.2% of patients, respectively. Postdural puncture headaches were observed in 21.7% of these patients. These data are in line with the literature.2
Surprisingly, the paramedian approach increases the risk of intraoperative occlusion of the catheter (odds ratio 3.58) despite the fact that the common opinion is that it offers a wider passage for both the needle and the catheter. Most of us adopt the paramedian approach if the median one fails, so it is frequently performed in complex spine (with arthrosis joint, kyphosis, scoliosis or vertebral fracture) procedures. It must be noted that adopting a reinforced catheter did not eliminate the risk of intraoperative occlusion.
At the end of the surgical procedure, immediately after extubation, 2.8% of patients reported severe pain even if the epidural catheter was presumed to be efficient during general anaesthesia. These data are simple but important because the patients should be always informed about the failure rate of an invasive procedure.
This study highlights that the incidence of minor complications related to the placement of a thoracic epidural catheter are frequent (nearly 6%). Indirectly, we found that complex spine increases the risk of these complications. Self-evaluation of minor complications is useful to correctly assess the risks of epidural catheter placement, to inform patients about it and to improve one's skill. Prospective observational studies are needed to better describe this kind of complications and related risk factors.
Acknowledgements relating to this article
Assistance with the study: the authors wish to thank their anaesthesiologist colleagues Dr Mario Ammatuna, Dr Anna Cardani, Dr Roberta Casirani, Dr Valerio Costagli, Dr Pasqualina Costanzo, Dr Ilaria Donati, Dr Giuditta Fallabrino, Dr Luca Fumagalli, Dr Edward Haeusler, Dr Antonio Maucione, Dr Silvana Migliavacca, Dr Lucia Miradoli, Dr Andrea Poli, Dr Paola Previtali, Dr Paolo Proto, Dr Giacomino Rebuffoni, Dr Giuseppe Rigillo, Dr Emiliano Tognoli and Dr Irene Vecchi for participating in data collection.
Financial support and sponsorship: none.
Conflicts of interest: none.