Reply from the authors

Abstract

Editor—We thank Dr Edgar for his sincere concern and constructive comments in our article.1Yoo KY Jeong CW Kim SJ et al.Altered cardiovascular responses to tracheal intubation in patients with complete spinal cord injury: relation to time course and affected level.Br J Anaesth. 2010; 105: 753-759doi:10.1093/bja/aeq267Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar Succinylcholine (SCh) has many advantages over other drugs for the rapid muscular relaxation that it produces for tracheal intubation and for the rapid offset of its effects. Thus, a rapid-sequence technique with SCh is preferable in the acute cord-injured who are at an increased risk of pulmonary aspiration. To standardize the study technique, we used SCh in all patients except for those who were at increased risk of hyperkalemia after SCh. Based on the review article describing ‘quadriplegics and paraplegics with persistent paralysis could have the potential for SCh-induced hyperkalemia throughout life’,2Martyn JAJ Richtsfeld M Succinylcholine-induced hyperkalemia in acquired pathologic states: etiologic factors and molecular mechanisms.Anesthesiology. 2006; 104: 158-169doi:10.1097/00000542-200601000-00022Crossref PubMed Scopus (289) Google Scholar Dr Edgar questions the use of SCh for tracheal intubation in the cord-injured. We agree with him that the absence of serum potassium measurements in patients may be a drawback in our study. However, in our previous study, we measured serum potassium levels to determine a temporal relationship for the development of hyperkalemic response to SCh in 119 cord-injured patients, in which none of 20 patients during first week post-injury and none of 31 patients after 6 months post-injury showed an increase in serum potassium >1 mEq litre−1 except for six patients (19.4%) after 6 months post-injury complicating pressor sore who showed increases of 1–2 mEq litre−1.3Yoo KY Lee J Kim HS Succinylcholine-induced hyperkalemia in patients with complete spinal cord injuries.Anesthesiology. 2000; 93: A1032Google Scholar We believe that the use of SCh for tracheal intubation is safe in patients who are beyond a vulnerable period to develop hyperkalemic response, extending from 3 days to 9 months post-injury.2Martyn JAJ Richtsfeld M Succinylcholine-induced hyperkalemia in acquired pathologic states: etiologic factors and molecular mechanisms.Anesthesiology. 2006; 104: 158-169doi:10.1097/00000542-200601000-00022Crossref PubMed Scopus (289) Google Scholar We again agree with Dr Edgar for the use of opioids to avoid cardiovascular instability at induction in cord-injured patients who have a high prevalence of virtually all risk factors for hypertension, including obesity, lipid disorders, metabolic syndrome, and diabetes.4Myers J Lee M Kiratli J Cardiovascular disease in spinal cord injury: an overview of prevalence, risk, evaluation, and management.Am J Phys Med Rehabil. 2007; 86: 142-152doi:10.1097/PHM.0b013e31802f0247Crossref PubMed Scopus (426) Google Scholar However, the cardiovascular and catecholamine responses to intubation change as a function of the time elapsed and the level of the cord injury. The pressor response to tracheal intubation is abolished in patients with quadriplegia, while the response is enhanced at 10 yr or more elapsed after the injury in paraplegia.1Yoo KY Jeong CW Kim SJ et al.Altered cardiovascular responses to tracheal intubation in patients with complete spinal cord injury: relation to time course and affected level.Br J Anaesth. 2010; 105: 753-759doi:10.1093/bja/aeq267Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar 5Yoo KY Lee J Kim HS Im WM Hemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with complete spinal cord injuries.Anesthesiology. 2001; 95: 647-651doi:10.1097/00000542-200109000-00017Crossref PubMed Scopus (15) Google Scholar 6Yoo KY Jeong CW Kim SJ Jeong ST Shin MH Lee J Cardiovascular and arousal responses to laryngoscopy and tracheal intubation in patients with complete spinal cord injury.Br J Anaesth. 2009; 102: 69-75doi:10.1093/bja/aen317Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar In addition, patients with chronic high-level paraplegia (T1–T4) show pronounced tachycardiac rather than pressor response.5Yoo KY Lee J Kim HS Im WM Hemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with complete spinal cord injuries.Anesthesiology. 2001; 95: 647-651doi:10.1097/00000542-200109000-00017Crossref PubMed Scopus (15) Google Scholar We believe that the dose of opioids should be determined based on the time elapsed and the level of injury in patients with complete spinal cord injury. Nevertheless, we only treated the hypertension (systolic arterial pressure >180 mm Hg) developed at induction by increasing the concentration of sevoflurane in our study. We excluded 15 (6.3%) patients just because the duration of intubation was longer than 15 s. They did not have any additional procedures for intubation. The important concept at induction in a patient with a known injury to the cervical spine is to successfully achieve tracheal intubation while minimizing the motion of the cervical spine. In this regard, a rapid-sequence induction in which tracheal intubation was performed 60–75 s after SCh would be acceptable, if not ideal, for a patient with spinal instability in the emergency setting. None declared.