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of stability while he received maintenance ipilim- Michael A. Postow, M.D. umab. A total dose of 27 Gy of radiotherapy was Margaret K. Callahan, M.D., Ph.D. administered in three fractions to an enlarging Jedd D. Wolchok, M.D., Ph.D. internal mammary lymph node, and regression of Memorial Sloan-Kettering Cancer Center distant, nonirradiated, and previously progress- New York, NY
[email protected] ing left axillary lymphadenopathy occurred. Since publication of their article, the authors report no furThese anecdotal cases support preclinical observations that show synergy between CTLA-4 ther potential conflict of interest. blockade and radiotherapy.1,2 We are enthusiasti1. Demaria S, Kawashima N, Yang AM, et al. Immune-mediatcally collaborating with Stanford University and ed inhibition of metastases after treatment with local radiation encourage participation in the clinical trial to test and CTLA-4 blockade in a mouse model of breast cancer. Clin this hypothesis prospectively. Correlative immu- Cancer Res 2005;11:728-34. 2. Dewan MZ, Galloway AE, Kawashima N, et al. Fractionated nologic analyses of peripheral blood and tumor but not single-dose radiotherapy induces an immune-mediated tissue will be essential to advancing a mechanis- abscopal effect when combined with anti-CTLA-4 antibody. Clin tic understanding of this potentially promising Cancer Res 2009;15:5379-88. combination.
Dysfunction of the Diaphragm To the Editor: Systematic and thorough fluoroscopic examination provides essential diagnostic information in patients with unilateral or bilateral diaphragmatic dysfunction. The physician can substantially improve patient comfort and cooperation by describing the examination, differentiating predominantly diaphragmatic breathing from chest-wall breathing, and providing verbal reassurance.1 Initially, each hemidiaphragm is observed during quiet breathing. While the patient stands on the fluoroscopy-table footplate, hemidiaphragmatic movement is observed during inspiration (slow, rapid, or both) from residual volume to total lung capacity in the anterior– posterior, oblique, and lateral projections. Most important, these maneuvers are repeated in the supine position. The restrictive function becomes more severe when the patient is in the supine position, as noted in the review by McCool and Tzelepis (March 8 issue).2 Hemidiaphragmatic excursion (or paradox) can be measured in centimeters or posterior intercostal spaces between fixed horizontal fluoroscopic cones.1 Normal movement of each hemidiaphragm may be readily distinguished from variations of normal movement, as well as from weakness and paralysis. Meticulous fluoroscopic examination supplants the limited “sniff test” at the cost of a few minutes and can be the first best test. Computed tomography (CT) of the chest with sagittal
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and coronal reformatting, CT fluoroscopy, and magnetic resonance imaging may have a future role in evaluation of the diaphragm. John D. Armstrong, II, M.D. National Jewish Health Denver, CO
[email protected] No potential conflict of interest relevant to this letter was reported. 1. Ch’en IY, Armstrong JD II. Value of fluoroscopy in patients
with suspected bilateral hemi-diaphragmatic paralysis. AJR Am J Roentgenol 1993;160:29-31. 2. McCool FD, Tzelepis GE. Dysfunction of the diaphragm. N Engl J Med 2012;366:932-42.
To the Editor: The review by McCool and Tzelepis lists the causes of diaphragmatic dysfunction; however, the authors failed to mention nerve-block–related hemidiaphragmatic paresis. Interscalene block, a form of brachial plexus block, is a common peripheral-nerve block that is performed preoperatively for upper-limb surgeries. It almost always results in some degree of ipsilateral phrenic-nerve blockade,1-3 which is caused by the spread of local-anesthetic solution to the cervical roots or to the surface of anterior scalene muscle, where the phrenic nerve traverses.3 Supraclavicular, deep cervical-plexus block and thoracic paravertebral block are also associated with hemidiaphragmatic paresis.4,5 It is important to differentiate surgical-trauma–related paresis
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correspondence
from these forms of hemidiaphragmatic paresis, because these are usually reversible. The duration of hemidiaphragmatic paresis depends on the type, strength, technique, and volume of local anesthetic used. Andaleeb A. Ahmed, M.B., B.S., M.P.H. Penn State Milton S. Hershey Medical Center Hershey, PA
[email protected] No potential conflict of interest relevant to this letter was reported. 1. Urmey WF, Talts KH, Sharrock NE. One hundred percent
incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography. Anesth Analg 1991;72:498-503. 2. Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anesth Analg 1992;74:352-7. 3. Sinha SK, Abrams JH, Barnett JT, et al. Decreasing the local anesthetic volume from 20 to 10 mL for ultrasound-guided interscalene block at the cricoid level does not reduce the incidence of hemidiaphragmatic paresis. Reg Anesth Pain Med 2011;36:1720. 4. Renes SH, van Geffen GJ, Snoeren MM, Gielen MJ, Groen GJ. Ipsilateral brachial plexus block and hemidiaphragmatic paresis as adverse effect of a high thoracic paravertebral block. Reg Anesth Pain Med 2011;36:198-201. 5. Emery G, Handley G, Davies MJ, Mooney PH. Incidence of phrenic nerve block and hypercapnia in patients undergoing carotid endarterectomy under cervical plexus block. Anaesth Intensive Care 1998;26:377-81.
tion, resulting in dyspnea. Armstrong suggests that placing the patient with bilateral diaphragmatic paralysis in the supine position and using a fixed extrathoracic object to reference the relative motion of the rib cage and diaphragm will enhance the diagnostic accuracy of fluoroscopy. Although this is theoretically correct, it may be difficult to discriminate between caudal motion of the diaphragm and cephalad motion of the rib cage when a patient has tachypnea. In addition, a supine examination may be difficult to complete because the patient with bilateral diaphragmatic paralysis may not be able to maintain this posture. However, if patients with bilateral diaphragmatic paralysis can maintain the supine posture, their compensatory breathing strategies may be sufficient to produce caudal displacement of the passive diaphragm similar to that seen when the patients are upright. We agree with Ahmed that hemidiaphragmatic paralysis may occur after brachial-plexus block for local anesthesia. In our review, we focused primarily on iatrogenic injuries to the phrenic nerve that frequently pose as diagnostic problems or lead to long-lasting dysfunction of the diaphragm. We also did not comment on other uncommon iatrogenic injuries to the phrenic nerve, such as those resulting from bronchial-artery embolization,3 radiofrequency ablation for atrial fibrillation,4 internal-jugularvein cannulation,5 or subclavian venipucture.5 F. Dennis McCool, M.D.
The Authors Reply: Armstrong asserts that fluo roscopic examination with the patient in the upright and supine position may circumvent some of the diagnostic inaccuracies encountered when fluoroscopy of the diaphragm is performed while the patient is upright.1 False negative results of fluo- Alpert Medical School of Brown University roscopic examinations are probably a consequence Providence, RI of the compensatory breathing strategies used by George E. Tzelepis, M.D. patients with bilateral diaphragmatic paralysis.2 University of Athens Medical School Patients with bilateral diaphragmatic paralysis Athens, Greece Since publication of their article, the authors report no furmay use abdominal muscles to actively exhale. ther potential conflict of interest. When the abdominal wall is relaxed, inspiration ensues and is accompanied by passive caudal 1. Ch’en IY, Armstrong JD II. Value of fluoroscopy in patients with suspected bilateral hemi-diaphragmatic paralysis. AJR Am motion of the diaphragm. A second compensa- J Roentgenol 1993;160:29-31. tory breathing strategy entails the use of the ac- 2. McCool FD, Mead J. Dyspnea on immersion: mechanisms in cessory inspiratory muscles to lift the rib cage patients with bilateral diaphragm paralysis. Am Rev Respir Dis 1989;139:275-6. during inspiration. The passive diaphragm then 3. Chapman SA, Holmes MD, Taylor DJ. Unilateral diaphragappears to move caudally because the rib cage is matic paralysis following bronchial artery embolization for hemoving in a cephalad direction. With either moptysis. Chest 2000;118:269-70. 4. Swallow EB, Dayer MJ, Oldfield WL, Moxham J, Polkey MI. breathing strategy, caudal motion of the dia- Right hemi-diaphragm paralysis following cardiac radiofrephragm may be erroneously interpreted as nor- quency ablation. Respir Med 2006;100:1657-9. mal. These compensatory breathing strategies 5. Paraskevas GK, Raikos A, Chouliaras K, Papaziogas B. Variable anatomical relationship of phrenic nerve and subclavian become ineffective when patients with bilateral vein: clinical implication for subclavian vein catheterization. Br diaphragmatic paralysis are in the supine posi- J Anaesth 2011;106:348-51.
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