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Adherent transversus abdominis plane catheter.

I read with interest the report of Tan and Trinca regarding the belligerent transversus abdominus plane catheter (1). I found myself precariously perched on the edge of my chair awaiting the final paragraphs to read an informative discussion. However what I was steeling myself for was not so much the excellent discussion on the topic of how, but rather, I was eager for a discussion about the where.

Where was the justification regarding safety for the dose of local anaesthetic administered using a technique that has a paucity of evidence to support efficacy? The four-day infusion of ropivacaine via the two catheters totalled 32 mg per hour. Local anaesthetic dosing limits are a complex issue that is consistently vexing for anaesthetists. Clinical dosing of local anaesthetic is guided first by the manufacturer's recommendation. Second (and when available), reference is made to published reports verifying safety, or alternatively, reporting complications and warning of the need for caution in dosing. The firm guidelines provided by the manufacturers include a host of qualifying remarks relating to the known factors that alter risk of toxicity. To date, as far as I am aware, we have little data to guide us on the safe dose range for catheters placed in the transversus abdominus plane. The manufacturer's recommendation for ropivacaine is 20 mg/hour for a peripheral nerve infusion and 28 mg/hour for epidural use. These doses are recommended for a 70 kg adult. While in paediatrics it is accepted to administer drugs on the basis of dose per kilo of body mass, such a dosing regimen is not comprehensively supported for local anaesthetic use in adults (2). This means that a 105 kg adult cannot necessarily be safely administered one and half times the ropivacaine dose that is recommended for a 70 kg adult.

Although no harm befell the patient, a comment from the authors on the potential danger of the described TAP catheter technique regarding the use of high local anaesthetic doses may have been helpful. This would serve as an educational point for those readers less experienced than the authors and who, on reading the report, may otherwise wish to add this technique to their own armamentarium without being fully conversant with all the issues.

A further comment is warranted on the reported total morphine dose over four days of 103 mg, for a purported opioid sparing technique. In a previous study, Beaussier et al (3) compared the outcomes for preperitoneal catheters delivering either an infusion of ropivacaine at 20 mg/hour or saline. The study population was colorectal surgery with a midline incision of 19 to 22 cm. The saline group had a mean morphine dose of approximately 89 mg over four days--not dissimilar to the TAP catheter patient in Tan and Trinca's report. For the active treatment group, administration of the ropivacaine infusion resulted in a substantial reduction in the mean morphine dose over four days to 52 mg, approximately. (Data were extrapolated by this author from the published three-day dose and visual estimation from the bar graph to derive an approximate total use over four days). The treatment group attained an earlier return of bowel function and were discharged from hospital sooner. Research on TAP catheters is awaited to determine whether they too can effectively minimise those opioid side-effects that are thought to be particularly detrimental to patients recovering from colorectal surgery (4).


(1.) Tan CO, Trinca J. An adherent transversus abdominis plane catheter. Anaesth Intensive Care 2011; 39:315-316.

(2.) Rosenberg PH, Veering BT, Urmey WF. Maximum recommended doses of local anesthetics: a multifactorial concept. Reg Anesth Pain Med 2004; 29:564-575.

(3.) Beaussier M, El'Ayoubi H, Schiffer E, Rollin M, Parc Y, Mazoit JX et al. Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal surgery: a randomized, double-blind, placebo-controlled study. Anesthesiology 2007; 107:461-468.

(4.) Kehlet H. Postoperative opioid sparing to hasten recovery: what are the issues? Anesthesiology 2005; 102:1083-1085.

Adherent tranversus abdominis plane catheter--Reply

We thank Dr Patullo for his interest in our case of an adherent transversus abdominis plane (TAP) catheter. His concerns regarding local anaesthetic (LA) toxicity during continuous infusions are timely, however we must point out that the total infusion rate of 32 mg/hour, including the initial block dose, is within our department's policy of a daily maximum of 800 mg of ropivacaine per day for an average-sized adult. It should be noted that the patient in question was heavier than 70 kg and did not have any organ dysfunction or other risk factors for reduced LA elimination.

No reference or product information specifies dosages for the continuous TAP catheter technique. Institutions such as ours have formulated protocols for their administration based on the factors described by Rosenberg et al (1), with no reported cases of local anaesthetic systemic toxicity (LAST) as a result of TAP blocks or infusions in the literature. The TAP space seems to display a relatively slow uptake of ropivacaine post bolus as seen in Griffiths (2) work with boluses of 3 mg/kg for 28 patients undergoing gynaecological laparatomy. Peak venous ropivacaine levels occurred at half an hour post injection and the mean level was 2.54 [micro]g/ml with no features of LAST. This was despite a venous ropivacaine level exceeding the 2.2 [micro]g/ml limit established in Knudsen's (3) study corresponding with early central nervous system signs of LAST.

Astra Zeneca's recent application to the Therapeutic Goods Administration (4) to include continuous wound infusions as an indication for ropivacaine was approved for continuous infusion but declined for infusion with intermittent boluses in April 2010. It appears that the rate of rise of ropivacaine plasma levels is of more significance than plasma level alone, as the only case of ropivacaine associated LAST reported in Di Gregorio's excellent review of the 97 published cases of LAST since 1979 (6) involved an epidural infusion of 24 mg/hour of ropivacaine with a convulsion following two large boluses of 112 mg of ropivacaine. However, Bleckner (5) demonstrated that intermittent ropivacaine boluses on a background infusion of 40 mg/hour can deliver safe analgesia

In answer to the request for comment on the risk of LA toxicity with TAP infusions, we must respond by saying that the potential for LA toxicity exists for any regional LA technique. There has been a long history of efficacy and safety within Victorian hospitals for perineural, epidural and paravertebral infusions used in the range of 16 to 32 mg/hour. Indeed, the clinical experience from St Vincent's Hospital, Melbourne is that up to 40 mg/hour perineural ropivacaine in a healthy patient over 70 kg is safe and data gathered on plasma ropivacaine levels during epidural use for orthopaedic patients is that 32 mg/hour is within safe limits. A level of protection is conferred by the perioperative increase in plasma alpha-1 glycoprotein levels, which resist an increase in free ropivacaine concentrations.

We must allay Dr Patullo's concerns on the question of efficacy of TAP analgesia. As with many regional analgesic techniques, success of the procedure is often operator-dependent, particularly when ultrasound guided and TAP catheters are no exception. There is evidence that TAP blocks reduce opioid requirements on average by 50% in abdominal surgery, including laparoscopy. Niraj et al (7) compared bilateral subcostal TAP catheter LA infusion and thoracic epidural, demonstrating equivalent VAS scores on coughing following upper abdominal surgery and no difference in opioid administration.

In conclusion, we strongly advise that ongoing TAP catheter LA administration can provide safe, efficacious postoperative analgesia for abdominal surgery. Dose and infusion rates should be tailored according to patient size, liver and renal function, and infusions should be commenced after a prudent delay if the immediate ongoing infusion rate would bring the patient's daily LA dose above the aforementioned guidelines. Additional caution is required when LA boluses are delivered on top of infusions.


(1.) Rosenberg PH, Veering BT, Urmey WF. Maximum recommended doses of local anesthetics: a multifactorial concept. Reg Anesth Pain Med 2004; 29:564-575.

(2.) Griffiths JD, Barron FA, Grant S. Plasma ropivacaine concentrations after ultrasound-guided transversus abdominis plane block. Br J Anaesth 2010; 105:853-856.

(3.) Knudsen K, Beckman SM, Blomberg S. Central nervous and cardiovascular effects of IV infusions of ropivacaine, bupivacaine and placebo in volunteers. Br J Anaesth 1997; 78:507-514.

(4.) Australian Public Assessment Report for Ropivacaine. Therapeutic Goods Administration. Submission no. PM-200901406-3-1, April 2010.

(5.) Di Gregorio G, Neal JM, Rosenquist RW. Clinical presentation of local anesthetic systemic toxicity. A review of published cases, 1979 to 2009. Reg Anesth Pain Med 2010; 35:181-187.

(6.) Bleckner L, Bina S, Kwon KH. Serum ropivacaine concentrations and systemic local anesthetic toxicity in trauma patients receiving long-term continuous peripheral nerve block catheters. Reg Anaesth 2010; 110:630-634.

(7.) Niraj G, Kelkar A, Jeyapalan I, Graff-Baker P, Williams O, Darbar A et al. Comparison of analgesic efficacy of subcostal transversus abdominis plane blocks with epidural analgesia following upper abdominal surgery. Anaesthesia 2011; 66:465-471.


Sydney, New South Wales



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Article Details
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Title Annotation:Correspondence
Author:Pattulu, G.; Tan, C.O.; Trinca, J.J.
Publication:Anaesthesia and Intensive Care
Article Type:Letter to the editor
Geographic Code:8AUST
Date:Sep 1, 2011
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