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Fasting time: are we now counting calories? A. Parameswari* and M. Vakamudi Chennai, India *E-mail:
[email protected]
Editor—We read with interest the article by Okabe and colleagues1 regarding the caloric composition of fluids and gastric emptying. Are we in a position to alter our fasting guidelines based on the information provided? Although enhanced recovery programmes suggest increased fluid intake, we need to be cautious, especially when it comes to children and preoperative oral intake. We feel more comfortable continuing our standard ASA-based fasting guidelines as opposed to studies that need to be validated in patients undergoing surgery who potentially have greater anxiety and hence decreased gastric emptying time, unlike healthy volunteers in the study.
Declaration of interest None declared.
Reference 1. Okabe T, Terashima H, Sakamoto A. Determinants of liquid gastric emptying: comparisons between milk and isocalorically adjusted clear fluids. Br J Anaesth 2015; 114: 77–82 doi:10.1093/bja/aev420
Underlying principle of liquid gastric emptying T. Okabe*, H. Terashima and A. Sakamoto Ibaraki, Japan *E-mail:
[email protected]
Editor—We would like to express our appreciation for your comment on our study.1 We are also concerned about the impact of various anxieties accompanying the wait for surgery on liquid gastric emptying. Needless to say, we addressed this important issue in the discussion section (the limitations of our study). When viewed from the opposite side, allowing patients to drink their favorite beverages may be useful in reducing pre-surgery stress and anxiety, which subsequently leads to improvement of liquid gastric emptying. Is one of our jobs to provide optimal comfort for all patients while ensuring safety and efficacy? Thus, we are currently engaged in further investigations to elucidate the underlying principle of liquid gastric emptying, and wait
for the opportunity to discuss your question again after publishing our next research.
Declaration of interest None declared.
Reference 1. Okabe T, Terashima H, Sakamoto A. Determinants of liquid gastric emptying: comparisons between milk and isocalorically adjusted clear fluids. Br J Anaesth 2015; 114: 77–82 doi:10.1093/bja/aev421
Early pharmacokinetics of ropivacaine without epinephrine after injection into the psoas compartment M. A. de Leeuw* and R. S. Perez Zaandam, The Netherlands *E-mail:
[email protected]
Editor—With considerable interest we read the article by Hubler and colleagues1 concerning the early pharmacokinetics of
ropivacaine without epinephrine, after injection into the psoas compartment. We encourage the analysis of the early phase of
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systemic absorption of high dose local anaesthetics administered into the psoas compartment (in the context of safety assessment of this technique!) and therefore congratulate the authors with this publication. We would like to make a few comments regarding the conclusions. The authors concluded that other studies, describing pharmacokinetics and plasma concentrations after a lumbar plexus block, were more focused on a combination of a psoas compartment block and a sciatic nerve block. Therefore, these studies lack a true time point zero for evaluating early systemic absorption kinetics from the psoas compartment. In addition, time intervals between the lumbar plexus block and first blood samples were often not registered, making analysis of early systemic absorption kinetics (and therefore comparison with Hubler’s and colleagues data) almost impossible. Although our study2 described the total plasma concentrations and pharmacokinetics of ropivacaine after a combined psoas compartment sciatic nerve block as well, we are of the opinion that results can be compared with the study of Hubler and colleagues. In our paper we described that 45 mg ropivacaine was first administered to the sciatic nerve and subsequently 180 mg was injected into the psoas compartment. The time at which all of the local anaesthetic solution (i.e. after the psoas compartment block) had been injected was taken as time zero and the time interval between both blocks was less than 7 min. In our opinion, early pharmacokinetic data found were more the result of the administered bolus into the psoas compartment rather than the small amount of local anaesthetics injected near the sciatic nerve, making a comparison with Hubler’s results legitimate. In this study2 we described a maximum total plasma concentration (median) of 900 ng ml−1 after a combined psoas compartment sciatic nerve block with 225 mg ropivacaine (45 mg sciatic nerve/180 mg psoas compartment) with added epinephrine (5 mcg ml−1). Hubler and colleagues described a higher maximum total plasma concentration (1070 ng ml−1) after administration of less ropivacaine (150 mg) without epinephrine into the psoas compartment. In conclusion, adding epinephrine as a vasoconstrictor to the local anaesthetic solution, has a substantial beneficial effect on the systemic absorption
and, in theory, reduces the risk of local anaesthetic systemic toxicity. Therefore we strongly agree with the authors’ opinion that adding epinephrine as a vasoconstrictor would be highly recommended. Finally, in our opinion, there is no contraindication to adding epinephrine as a vasoconstrictor to a local anaesthetic solution. We have described the haemodynamic changes during a psoas compartment - sciatic nerve block with added epinephrine for elective orthopaedic surgery in an observational case series study.3 Besides a small but clinically irrelevant decrease of arterial bp, there were no undesired haemodynamic sideeffects (especially no epinephrine related tachycardia, hypertension or severe dysrhythmias) after injecting high doses of local anaesthetics with added epinephrine (5 mcg ml−1) into the psoas compartment. However, one should be cautious of using epinephrine as an additive in peripheral nerve blocks, in patients with a low tolerance for a decrease in neural blood flow (severe diabetes, peripheral vascular disease), as described by Rosenberg and colleagues.4
Declaration of interest None declared.
References 1. Hubler M, Planitz MC, Vicent O. Early pharmacokinetic of ropivacaine without epinephrine after injection into the psoas compartment. Br J Anaesth 2015; 114: 130–5 2. de Leeuw MA, Bet PM, Wilhelm AJ, et al. Total plasma concentrations of bupivacaine, levobupivacaine and ropivacaine after combined psoas compartment – sciatic nerve block. Eur J Anaesthesiol 2009; 26: 1083–5 3. de Leeuw MA, Slagt C, Hoeksema M, Zuurmond WW, Perez RSGM. Hemodynamic changes during a combined psoas compartment – sciatic nerve block for elective orthopedic surgery. Anesth Analg 2011; 112: 719–24 4. Rosenberg PH, Veering BT, Urmey WF. Maximum recommended doses of local anesthetics: a multifactorial concept. Reg Anesth Pain Med 2004; 29: 564–75 doi:10.1093/bja/aev422
Reply from the authors
Reply M. Hübler* Dresden, Germany *E-mail:
[email protected]
Editor—We thank de Leeuw and Perez for their comments on our article.1 It is indeed true that their study2 resembles our study such as they also investigated ropivacaine pharmacokinetics and took arterial blood samples. In their study, 20% of the ropivacaine was injected near the sciatic nerve and the remaining 80% into the psoas compartment. The time intervals between the first injections (sciatic nerve block) and the first blood samples were 9 min. They therefore believe that the early pharmacokinetic data were more the result of the administered bolus into the
psoas compartment, which were completed 2 min before the blood samples were drawn. Although their interpretation is eventually true, the fact remains that two injections were performed and probably influenced their results. The most striking aspect when comparing the two studies is the effect of epinephrine: in nine of ten patients, we measured the plasma concentrations of ropivacaine immediately following the injections−30s later in all ten patients. The range of Cmax was 422–2864 ng ml−1, and the range of Tmax was 10–30 min.
