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Ann Thorac Surg 2001;72:1796
© 2001 The Society of Thoracic Surgeons

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Correspondence

Traumatic rupture of the aorta and paraplegia

^a Department of Surgery, The University of Tennessee, Health Sciences Center, 956 Court Ave, Memphis, TN 38163, USA
^b Division of Biostatistics and Epidemiology, The University of Tennessee, Health Sciences Center, Memphis, TN 38163, USA

e-mail: jpate{at}utmem.edu

To the Editor

Karmy-Jones and coauthors [1] report that the pulmonary vein is a safer site of cannulation for left heart bypass than the left atrial appendage. Their excellent results convincingly demonstrate the value of this technique and thus accurately reflect the title. However, they depart from the title into discussions of paraplegia, aortic cross-clamp times, and pump support. They wrote: "Cross-clamp time was not significantly different between these groups" (patients in whom paralysis developed versus patients without paralysis) and "Logistic regression did not identify mechanical support as being independently associated with a significant reduction in paralysis." These statements, although accurate in this series, may be taken out of context by those not experienced with this injury, and this could result in unnecessary catastrophic paralysis in some patients. The raw, ungrouped data from this study would be of interest if the authors were to address these subjects.

Several confounding factors influence the results of this statistical analysis. The clinical material includes patients with tears in the ascending aorta and arch as well as the classic isthmus injuries. In fact, this wide inclusion is a common fault in the literature on the subject; even the referenced large multicenter report by Fabian and associates [2] from our department did this. Use of a simple classification system [3], which is done more in Europe than in the United States, would obviate several of the more important variables.

The denigration of the importance of cross-clamp time is dangerous. Karmy-Jones and coauthors found that in the group of patients who underwent repair without any type of circulatory support, ie, the "clamp and sew" groups, those who sustained paralysis had a mean cross-clamp time of 43.4 ± 23.1 minutes (interquartile range could be 20 to 66 minutes) and those patients who did not had a mean clamp time of 26.6 ± 10.7 minutes (interquartile range, 16 to 37 minutes), which was not a significant difference with the small numbers. However, the data reveal that in all patients who did not have development of paraplegia, cross-clamp time was less than 37.3 minutes.

Other confounding factors include the following: presence or absence of preoperative neurological injury; reasons for selecting a particular surgical approach; medical management; pharmacological manipulation during anesthesia; infusing or not infusing shed blood; inability to tolerate one-lung anesthesia; and rupture before proximal aortic control. Did rupture before proximal control of the aorta occur during dissection without a pump to rapidly introduce massive blood loss and support the circulation or during aortography?

Multivariate regression analysis of data from patients with such complex injuries may serve to obscure important observations and demonstrates their high variability. In fact, in patients with injuries to the ascending aorta and arch and in those who could not tolerate one-lung anesthesia, repair could not have been achieved with the "clamp and sew" technique; this selection probably biased mortality and possibly rate of paraplegia against the pump group. The statistical comparisons between groups may have been like those between apples and oranges.

The simple facts remain: 33 of 60 patients survived repair with the "clamp and sew" technique, and 8 had development of paralysis, whereas 48 of 54 survived repair with mechanical distal support, and none experienced paralysis.

References

1. Karmy-Jones R., Carter Y., Meissner M., Mulligan M.S. Choice of venous cannulation for bypass during repair of traumatic rupture of the aorta. Ann Thorac Surg 2001;71:39-42.[Abstract/Free Full Text]
2. Fabian T.C., Richardson J.D., Croce M.A., et al. Prospective study of blunt aortic injury: multicenter trial of the American Association for the Surgery of Trauma. J Trauma 1997;42:374-383.[Medline]
3. Pate J.W. Is traumatic rupture of the aorta misunderstood?. Ann Thorac Surg 1994;57:530-531.[Medline]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): James W. Pate Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pate, J. W. Articles by Tolley, E. A. Search for Related Content PubMed PubMed Citation Articles by Pate, J. W. Articles by Tolley, E. A. Related Collections Great vessels Related Article