In Response

Abstract

Our data clearly show that there is communication between the paravertebral and epidural spaces, with contrast spread into the epidural space in 40% of cadavers. Epidural and intercostal spread of contrast likely contribute significantly to analgesic efficacy from paravertebral blockade, and this is stated in our conclusion.1 We make no assertions that paravertebral blockade is the preferred method of pain relief, nor do we assert that it is “superior or safer” after thoracic surgery. We state that the paravertebral space can be easily identified with ultrasound on all cadavers and that an in-plane needle approach using ultrasound is feasible and reliable. We provide an anatomical basis for the efficacy of paravertebral blockade and state clearly that spread of contrast in cadavers is highly variable. We conclude that a dual injection technique at 2 different levels covers more thoracic dermatomes than does a single injection technique, because of intercostal spread, but given that ours is a cadaveric study, we make no comment on the quality of analgesia nor complications such as hypotension or nausea. We emphasize in our conclusion that these findings need to be confirmed in a patient population before definite recommendations are made. We found no evidence of spread to the subarachnoid space.1 Finally, we agree with Norum and Braevik that the paravertebral space is indeed in close proximity to pleura and the spinal cord2 and also agree that the indications, contraindications, and complications of paravertebral block can be similar to those of a thoracic epidural and that postoperative patients should be monitored in a similar manner. Brian Cowie, MB, BS, FANZCA Desmond McGlade, MBBS, FANZCA Michael J. Barrington, MBBS, FANZCA Department of Anaesthesia St. Vincent's Hospital Melbourne, Australia [email protected] Jason Ivanusic, PhD Department of Anatomy and Cell Biology University of Melbourne Melbourne, Australia