Epidural catheters of the multi-orifice type: dangers and complications

Lateral deviation of four types of epidural catheters from the lumbar epidural space into the intervertebral foramen

Background

During epidural anesthesia, the catheter tip occasionally deviates from the epidural space into the intervertebral foramen, resulting in inadequate anesthesia.

Methods

During postoperative plain radiography, iohexol was injected via the epidural catheter to determine its position and to observe the spread of the material. After exclusion of seven patients with catheters that migrated into the subcutaneous area and 25 patients with no evidence of the contrast medium, 415 patients were evaluated. We retrospectively compared patients to determine whether the incidence of deviation into the intervertebral foramen differed between four types of epidural catheters. We also investigated the load applied to the catheter tip using a Shimadzu Autograph AG-X-500 N-111 universal testing machine.

Results

Deviation of the epidural catheter into the intervertebral foramen was observed in eight and 33 patients in the Hakko and Perifix Soft tip catheter groups, respectively. The incidence of deviation was higher in the Perifix Soft tip catheter group, and lower in the FlexTip Plus and Perifix FX catheter groups. A rapid increase was observed in the force exerted on the tips of the Hakko and Perifix Soft tip catheters, while the force transmitted to the tips of the FlexTip Plus and Perifix FX catheters gradually increased and then reached a plateau at a low level.

Conclusions

The incidence of deviation was significantly lower with spiral-type catheters than with other types of catheters. This might be attributable to the gradual transmission of a lower level of force to the tip in spiral-type catheters.

Epidural catheter design: history, innovations, and clinical implications

Epidural catheters have evolved during the past several decades, as clinicians and manufacturers have sought to influence the quality of analgesia and anesthesia and reduce the incidence of catheter-related complications. This evolution has allowed a transformation from single-shot to continuous-infusion techniques and resulted in easier passage into the epidural space, more extensive medication distribution, and ultimately, improved patient satisfaction. Particular catheter features, including the materials used, tip design, and orifice number and arrangement, have been associated with specific outcomes and provide direction for future development.

Insertion length and resistance during advancing of epidural catheter

PURPOSE

The migration of an epidural catheter into the intravascular and subarachnoid spaces sometimes occurs. This study was designed to investigate where the resistance was felt during the advancing of the catheter into the epidural space and whether the length of catheter advanced in the epidural space affected the incidence of catheter migration.

METHODS

One hundred and twenty women, American Society of Anesthesiologists (ASA) 1 or 2, scheduled to undergo lower abdominal surgeries with epidural anesthesia were randomly assigned to two groups according to the length of the epidural catheter advanced; 4 cm (n = 60) or 8 cm (n = 60). The length where resistance to advancing the catheter was perceived was recorded in all patients, and the incidence of aspiration of blood or cerebrospinal fluid (CSF) was obtained. Further, the catheters removed 48 h after surgery were scrutinized for their bending sites.

RESULTS

Resistance was felt in 83 (69.2%) patients and the mean length in the epidural space at which resistance was found was 2.5 +/- 1.2 cm. Blood was aspirated in 9 (7.5%) patients when resistance to advancing the catheter was overcome, but CSF was aspirated in no patient. A distal bend was observed 2.4 +/- 1.3 cm from the tip of the catheter, and the sites of bending were correlated with the length where resistance was encountered. An additional proximal bend was observed in 35 (58%) patients in the 8-cm group, and in 2 patients (3%) in the 4-cm group (P < 0.001), probably due to coiling of the catheter.

CONCLUSION

At approximately 2.5 cm in the epidural space, advancing an epidural catheter causes resistance. Further advancing past this point may cause migration of the catheter into the vessels, or the coiling of the catheter.

Detection of Intravascular Epidural Catheter Placement: A Review

Intravascular placement of an epidural catheter is recognised as a potentially fatal complication of epidural anaesthesia and analgesia. Up to 10% of epidural catheters may be inserted into an epidural vessel, the majority of which will be recognised; however, a proportion (1% of all epidural catheters inserted) may not be identified as lying intravascularly. Opinions differ on the optimal method for identifying intravascular catheters and no perfect method exists. Some debate the need for a test of correct location, as a lack of specificity may mean that a proportion of correctly located catheters are withdrawn and resited. This review outlines the incidence and risk factors associated with intravascular placement and aims to evaluate the detection methods that have been described, in an attempt to answer the question: “What is the optimal way of detecting intravascular placement of an epidural catheter?”

Are combined spinal-epidural catheters reliable?

The combined spinal-epidural (CSE) technique can rapidly relieve labor pain. However, the location of the epidural catheter is initially uncertain. In an emergency, this untested catheter may fail to provide adequate anesthesia. This study compared the efficacy of catheters placed as a part of an epidural or needle-though-needle CSE technique in laboring women. Patients requesting pain relief received either epidural (n=601) or CSE (n=1061) analgesia. All patients had a 20 gauge, closed tip multi-holed polyamide catheter. (B. Braun Medical, Inc.) inserted 2-8 cm into the epidural space. Catheters were tested to rule out intrathecal and intravascular location. Then, epidural patients received 10-20 ml local anesthetic +/- opioid in divided doses. CSE patients received and infusion of 0.083% bupivacaine with opioid at 10-15 ml/h. Of the 1495 catheters that were adequately tested, those inserted as part of a CSE technique were more likely to produce bilateral sensory change and adequate analgesia than were those inserted without prior spinal analgesia (98.6% vs 98.2%, P<0.02). Stand-alone epidural catheters were more likely to produce neither sensory change nor analgesia than those inserted as part of CSE technique (1.3% vs 0.2%, P<0.02). The only catheters that failed completely and were not intravascular were stand-alone epidural catheters. In this clinical setting, catheters inserted as part of a CSE technique had a high probability of being in the epidural space and functioning appropriately.

An in vitro evaluation of flow from multihole epidural catheters during continuous infusion with four different infusion pumps

We have observed in vitro the distribution of flow from 10 identical multihole epidural catheters during continuous infusion with four different infusion pumps. The pumps chosen were the B Braun Perfusor Secura FT syringe driver and three volumetric infusion pumps utilising different pumping mechanisms (Dekra 3000 BL, Graseby 500 and CADD-Prizm). These pumps infused 0.9% saline through each catheter at 5 ml.h-1, 15 ml.h-1, 50 ml.h-1 and 99 ml.h-1 for 3 min. The number of holes through which flow occurred and the catheter hole where flow predominated during each test were recorded. The pressure waveform generated during each infusion was displayed and the peak pressure recorded. In 38 of the 160 tests (24%) the largest proportion of flow was seen at the hole closest to the catheter tip. The CADD pump generated multihole flow during significantly more tests (p < 0.0001) than the other pumps and produced significantly higher driving pressures (p < 0.001) at all infusion rates compared with the Graseby and Perfusor pumps. The CADD was the only pump to produce flow from all three holes of the catheter at 5 ml.h-1.

Does epinephrine improve the diagnostic accuracy of aspiration during labor epidural analgesia?

Aspiration reliably detects almost all IV multiorifice epidural catheters. Although a supplemental epinephrine 15-microg test dose may detect the rare IV catheter that does not yield blood on aspiration, false-positive epinephrine responses may cause some women to unnecessarily undergo repeat epidural catheter insertion. We evaluated 532 consecutive eligible patients requesting neuraxial labor analgesia. Patients were excluded if they had a contraindication to epinephrine or if they received intrathecal sufentanil/bupivacaine. Multiorifice catheters were inserted 4-6 cm into the epidural space as part of an epidural (n = 305) or combined spinal-epidural (n = 270) technique. We used aspiration, a lidocaine/epinephrine test dose, and bolus injection or infusion of dilute bupivacaine/sufentanil solutions to systematically determine IV, intrathecal, or epidural catheter location. Aspiration alone detected 47 of 48 intravascular catheters. There were 10 positive epinephrine responses: 2 were true positives, 7 were falsely positive (subsequent local anesthetic injection/infusion produced bilateral sensory change and analgesia), and 1 catheter was removed without further testing. Aspiration detected almost all intravascular catheters. Although the epinephrine test dose did detect one catheter that proved to be in a blood vessel, 87.5% of positive responses occurred in women without intravascular catheters.

IMPLICATIONS

Epidural catheters may enter a blood vessel. Many clinicians use epinephrine to detect these catheters. Because aspiration alone detects almost all IV multiorifice catheters in laboring women, a subsequent epinephrine test dose may be unnecessary.

Bilateral trigeminal nerve palsy during an extensive lumbar epidural block

A rare case of trigeminal nerve blockade arising in the course of obstetric lumbar epidural anaesthesia is described. There was extensive bilateral spread of nerve-block up to the C4 level with respiratory distress after top-up for caesarean section, and subsequent epidurography revealed high epidural spread of contrast. The mechanism of the trigeminal nerve palsy was the source of some controversy, particularly as to whether intracranial spread of local anaesthetic had occurred, possibly following accidental subdural or subarachnoid injection.

An unusual complication following combined spinal-epidural anaesthesia for caesarean section

The combined spinal-epidural technique is widely used in obstetric anaesthetic practice. Epidural catheter migration through a dural hole is a theoretical but rarely described complication. We report a case of acute and life-threatening respiratory depression following administration of diamorphine through an epidural catheter after a single space combined spinal-epidural technique for caesarean section. We believe this complication occurred as a result of catheter migration through a dural hole into the subdural space and rupture of the thin arachnoid layer causing massive subarachnoid blockade.

A comparison of multiport and uniport epidural catheters in laboring patients

The relative incidence of technical difficulties associated with multiport (three lateral ports) and uniport (single distal port) epidural catheters remains controversial. As part of a continuing institutional evaluation of epidural catheter insertion, 500 parturients were randomized to have either a multiport or a uniport epidural catheter inserted 6 cm into the epidural space. Multiport epidural catheters were associated with inadequate analgesia less often and required manipulation less often than uniport epidural catheters. The incidences of intravenous cannulation, subsequent catheter dislodgement, and catheter replacement were similar for each catheter type. No multiport epidural catheter was associated with multicompartment placement. We conclude that multiport epidural catheters are preferable for use in laboring patients since they reduce the incidence of inadequate epidural analgesia.

Superiority of multi-orifice over single-orifice epidural catheters for labor analgesia and cesarean delivery

STUDY OBJECTIVE

To investigate whether a change from a single-orifice to multi-orifice catheter could reduce the incidence of inadequate epidural blocks requiring replacement of the epidural catheter in obstetric patients.

STUDY DESIGN

Prospective before-after cohort study.

SETTING

Obstetric unit at a university hospital.

PATIENTS

872 patients requesting epidural analgesia for vaginal delivery or cesarean section.

INTERVENTIONS

Patients received epidural analgesia via single-orifice (n = 433) or multi-orifice (n = 439) epidural catheters, depending on the month of the trial.

MEASUREMENTS AND MAIN RESULTS

Patient characteristics, obstetric procedure, anesthesiologist characteristics, and details of epidural placement did not differ significantly between the groups. The overall replacement rate was 14.3% in the single-orifice group versus 9.3% in the multi-orifice group (p = 0.032). There were no difference in the frequency of replacement for subarachnoid placement or migration, immediate intravascular placement, vascular migration, or absence of any block. Significantly fewer catheters were replaced in the multi-orifice group for inadequate analgesia, defined as unblocked segments or unilateral block (6.4% vs. 2.8%, p = 0.018). Paresthesias were less common in the multi-orifice group (22.4% vs. 31.5%, p = 0.003). There were no unrecognized subarachnoid or vascular catheter placements in either group.

CONCLUSIONS

The multi-orifice design offers significant advantages over the single-orifice type for obstetricepidural analgesia.

Lumbar epidurography with multi-orifice and single orifice epidural catheters

The spread of iohexol in the epidural space was studied using two types of epidural catheter. Twenty pre-menopausal women undergoing hysterectomy received lumbar epidural analgesia via either multi-orifice or single orifice catheters. Twenty-four hours after surgery, iohexol was injected before catheter removal with the patient lying supine. Whereas there was no significant difference in the total number of vertebral segments covered by dye or the total number of segments reached above or below the level of epidural insertion, spread was more even to the right and left of midline using the single orifice catheters. Sacral spread of dye was only observed when a single orifice catheter was used. Epidural catheter design affects the distribution of solutions in the epidural space, with single orifice epidural catheters producing more even distribution of dye with sacral extension.

Misplacement of multihole epidural catheters--a report of two cases

The misplacement of a multihole (three lateral holes) epidural catheter such that it lies partly in the subdural space is demonstrated in two patients by means of epidurographic studies.

[Dangers and complications in pain therapy with epidural and intrathecal catheters.]

Pain therapy with epidural or intrathecal catheters is an invasive method. These techniques have specific indications in both acute and chronic pain therapy. However, complications can occur. Thus, the potential complications and the therapy necessary must be known.Drugs: Complications resulting from acute local anesthetic intoxication's are rare. High plasma levels during chronic therapy may lead to confusion. Respiratory depression can occur in opioid naive patients up to 12 (-24) h after injection. Adequate monitoring is a prerequisite for this therapy. After application of clonidine, hypotension is frequent in hypertonic and hypovolemic patients. Epidural or intrathecalcatheter placement can result in therapeutic failure, trauma by punction and inability to place the catheter. During chronic therapy, technical problems can occur, e.g., dislocation, occlusion. To exclude intrathecal and intravascular placement, application of a test dosage of a local anesthetic with adrenaline is recommended.Neurological complications can result in nerve root deficit or "simple" post-spinal headache, but cauda equina syndromes, paralyses, intracranial bleeding, sinus thrombosis and central neurological deficits have been reported. Skininfection at the insertion site of the catheter has been observed with an incidence of 1.9 to 7.7%. A spinal infection with neurological deficit is rare. Spinal infections are often associated with other diseases. Spinalhematomas are rare. Coagulation disorders and anticoagulants can lead to bleeding. Intravenous heparin should be avoided, because this is frequently associated with spinal bleeding. Therapy with cumarines is a contraindication for insertion of spinal catheters.Monitoring: During treatment with spinal catheters, adequate monitoring increases safety for the patients. Efficacy of the injections, puncture site and the neurological status should be documented daily. Neurological deficits must be diagnosed without losing time and adequate therapy must be initiated.

A new epidural catheter. Closer eyes for safety?

A new design of epidural catheter with three lateral eyes placed in close proximity to its closed end is described. Prototype models of this catheter were tested in 200 obstetric and surgical patients. In a single-blind randomised study it was found to be easy to insert and highly satisfactory in use, when compared to the current catheter type, with three widely spaced lateral eyes. It is hoped that the close spacing of the eyes will eliminate the complication of multicompartment block, as seen with earlier multihole catheters, and improve the safety of epidural block.

Lumbar regional anaesthesia and prophylactic anticoagulant therapy. Is the combination safe?

A survey has been carried out in all Danish anaesthetic departments (n = 80) regarding the attitude towards the use of epidural/spinal lumbar analgesia in patients who were receiving prophylactic anticoagulant therapy for the prevention of thromboembolism. About 60% of the departments used the techniques in patients receiving low-dose heparin and no side effects had been experienced. Spinal and epidural anaesthesia were in general regarded as being contraindicated in patients fully anticoagulated with vitamin K antagonists. In the world literature, the attitude towards the combination is conflicting. No randomised trial has been performed and complications are almost entirely confined to patients fully anticoagulated with vitamin K antagonists. Only one case of an epidural haematoma has been recorded when subcutaneous low-dose heparin was used as thromboprophylaxis.

Extradural vein puncture--an avoidable complication

Accidental cannulation of an extradural vein is a troublesome and potentially serious complication of extradural catheter insertion. This study was conducted to assess the influence of posture, catheter size and the injection of saline before catheter insertion, on its occurrence. Eight different techniques were studied based on combinations of these three factors. There was no difference in incidence with respect to posture. The use of 18-gauge catheters, after injection of 10 ml of 0.9% saline, resulted in a significant (p less than 0.01) reduction in the incidence of extradural vein cannulation. This technique is recommended in obstetric patients as a means of avoiding accidental intravenous injection of local analgesic.

Asymmetric onset of sympathetic blockade in epidural anaesthesia shows no relation to epidural catheter position

A radiological study was performed of the relation between onset of sympathetic blockade in lumbar epidural anaesthesia and the position of the epidural catheter. In 20 patients scheduled for extracorporeal shock wave lithotripsy (ESWL), the onset of sympathetic blockade after epidural anaesthesia (catheter insertion at the presumed level L2-L3, and injection of 20 ml prilocaine 2% with epinephrine 5 micrograms/ml) was objectively evaluated by photoplethysmography. The onset was asymmetrical in 18 patients, and symmetrical in only two. Just before the start of ESWL, the position of the epidural catheter was checked by radiography after injection of 0.5 ml iohexol 300 mg/ml (Omnipaque 300). The radiopaque contrast medium was found median (n = 2), right (n = 7) and left (n = 11) of the midline. In only 9 patients was the earliest onset of sympathetic blockade correlated with the side of the catheter position, and thus no relation between catheter position and onset of sympathetic blockade was found.

Unexpectedly extensive conduction blocks in obstetric epidural analgesia

Life-threatening extensions of conduction block during obstetric epidural analgesia can be classified according to the risk to the mother. High blocks that occur in the presence of the anaesthetist should present a readily treatable problem. Reports of total spinal anaesthesia that occur with no anaesthetist in attendance call for a reappraisal of present practice. Changes in current anaesthetic practice, which might increase safety with epidural analgesia, are top-ups by midwives, but only when the anaesthetist is on the delivery suite; repeated assessment of the nature of the conduction block by an anaesthetist; and continuous infusions with anaesthetist-only top-ups.

A comparison between open-end (single hole) and closed-end (three lateral holes) epidural catheters. Complications and quality of sensory blockade

A randomised, single-blind study was conducted on 802 parturient women who required epidural analgesia, to compare open-end (single hole) with closed-end (three lateral holes) epidural catheters. The complication rate after catheter insertion was not statistically different between the two groups, but the number of unsatisfactory blocks was significantly higher in the open-end group (p less than 0.001). The closed-end catheters were easier and less painful to place, but gave a higher incidence of bloody taps. The open-end catheters caused sensory blockade to be more frequently unilateral and more frequently missed sensory segments. This resulted in a significantly higher number of open-end catheters that required replacement (p less than 0.001). Open-end catheters despite their theoretical advantages in the detection of intravenous and subarachnoid placement caused an unacceptably high incidence of unsatisfactory sensory blockade.

[Lumbar epidural catheterization: estimation of the length of the inserted catheter]

A catheter in the epidural space can be the cause of various iatrogenic complications. In order to avoid leaving too great a length in the lumbar epidural space during epidural anaesthesia, graduated Tuohy needles can be used (Perifix), together with graduated epidural catheters. On the latter, a special marking shows that, when it reaches the needle hub, the catheter tip is at the needle bevel. Approximately 5 to 7 cm of catheter length are introduced into the epidural space. The needle is removed and placed upside down next to the catheter, with the hub in contact with the patient's skin. In this position, the distance between the special marking on the catheter and the graduation on the needle which marked the skin level is equivalent to the length of catheter in the epidural space. This distance, and therefore catheter length, can then be reduced to about 4 cm by carefully withdrawing the catheter. Some possible improvements of catheters and needles are discussed. Knowing exactly how much catheter is within the epidural space could be of particular importance whenever that space is uncommonly far from the patient's skin: obesity, oedema, use of the paramedian route or a very oblique angle of the needle in the sagittal plane.

Differential flow from multihole epidural catheters

The pressures used in vivo to administer epidural doses of local anaesthetic were recorded for 16- and 18-gauge multihole catheters. Observations were made on 10 patients in labour for each catheter gauge. The pressure range for the 16-gauge catheters was 39.9-266 kPa, with a mean of 167.2 kPa, and for 18-gauge, a range of 53.2-266 kPa, mean, 159 kPa. Similar pressures were then applied in vitro to 10 catheters of each gauge, and the flow of fluid observed from the three holes. For each size of catheter, with increasing pressure, flow appeared at the proximal, then the middle, and finally the distal hole. This emphasises that the effect of epidural doses can vary depending on the pressure of injection, especially if the catheter had been passed partially through the dura.

[Systemic toxicity of local anesthetics. Pharmacokinetic and pharmacodynamic factors]

Local anaesthetics can have systemic adverse effects, mostly affecting the central nervous system and the heart. The physicochemical characteristics of the different local anaesthetics are recalled, for they determine the relationship between structure, activity and toxicity. The pharmacokinetic factors involved in the toxic effects of local anaesthetics, whether the drug is given in a single extravascular dose or, accidentally, within a blood vessel, are discussed. The toxic effects of repeated administrations of local anaesthetics depend on the metabolism of the drug as well as on pharmacokinetic factors. Possible maximal doses and drug interactions are also discussed. The mechanism of action of local anaesthetics, which block the sodium channel, explains their tissue toxicity and, more specifically, their central nervous and cardiovascular toxicities, which are more pronounced for the more potent local anaesthetic agents (bupivacaine, etidocaine). Systemic maternal effects and transplacental passage probably explain their foetal toxicity. Specific toxic effects are seen with some drugs, such as methaemoglobinaemia and allergic reactions (rarely for amide agents). Overall, local anaesthetic accidents are rare, but they must be prevented.