Correspondence
preoperative ECG at rest showed left ventricular hypertrophy due to his untreated hypertension, there was no indication of abnormal left ventricular wall motion on transthoracic echocardiography. After the proposed surgery was uneventfully completed in 230 min, he was transferred to the postanaesthesia care unit without emergence. In the unit, mechanically ventilated support partially assisted his breathing with the trachea intubated under continuous sedation. On the second postoperative day, he was gradually weaned from the mechanical ventilation after stopping the sedation. During the weaning process, significant ST-segment depression in lead V5 was found once the heart rate exceeded 90 beats min21, and the maximum value of ST-segment depression in lead V5 reached 0.33 mV. Bolus doses of i.v. landiolol 2.5 or 5 mg were given until the heart rate was ,90 beats min21. A total dose of 15 mg landiolol was given over approximately 5 min with recovery of the ST-segment depression without significant change in arterial pressure. As landiolol has a short duration of action, it was administered by continuous infusion at 5–10 mg kg21 min21 to prevent return of the tachycardia and ST-segment depression. Although an amount of 15 mg of landiolol was necessary to achieve the target reduction in heart rate below the patient’s ischaemic threshold, the arterial pressure remained almost unchanged, despite the potential for landiolol to impair the cardiac contraction by a negative inotropic action. Harasawa and colleagues2 reported that 0.1 or 0.2 mg kg21 of bolus landiolol exerted an equipotent effect on heart rate reduction without affecting arterial pressure for the treatment of intraoperative tachycardia in surgical patients. Other clinical studies also demonstrated that 0.1– 0.3 mg kg21 of bolus landiolol effectively prevented tachycardia caused by tracheal intubation during anaesthesia induction.3 – 5 In our case, small doses of landiolol was titrated in this patient until the heart rate decreased below the ischaemic threshold, and a dose of 0.27 mg kg21 was required over 5 min. Previous studies have excluded patients with coronary artery disease, but the pharmacological effect of landiolol observed in our patient including dose, onset time, and arterial pressure were consistent with those described previously.2 – 5 However, in the case of myocardial ischaemia associated with tachycardia, it may be safer to administer landiolol in a relatively small doses or continuously while monitoring the haemodynamic response than to give 0.2–0.3 mg kg21 as a bolus infusion because of the possibility of further ischaemic myocardial dysfunction.
1 Landesberg G, Mosseri M, Zahger D, et al. Myocardial infarction after vascular surgery: the role of prolonged, stress-induced, ST depression-type ischemia. J Am Coll Cardiol 2001; 37: 1839 – 45 2 Harasawa R, Hayashi Y, Iwasaki M, Kamibayashi T, Mashimo T. Bolus administration of landiolol, a short-acting, selective b1blocker, to treat tachycardia during anesthesia: a dose-dependent study. J Cardiothorac Vasc Anesth 2006; 20: 793 – 5 3 Yamazaki A, Kinoshita H, Shimogai M, et al. Landiolol attenuates tachycardia in response to endotracheal intubation without affecting blood pressure. Can J Anaesth 2005; 52: 254 – 7 4 Goyagi T, Tanaka M, Nishikawa T. Landiolol attenuates the cardiovascular response to tracheal intubation. J Anesth 2005; 19: 282– 6 5 Sugiura S, Seki S, Hidaka K, Masuoka M, Tsuchida H. The hemodynamic effects of landiolol, an ultra-short-acting b1-selective blocker, on endotracheal intubation in patients with and without hypertension. Anesth Analg 2007; 104: 124 – 9
Y. Suzuki A. Morihara Y. Desaki K. Terao T. Kido K. Semba Y. Takasaki* Uwajima, Japan *E-mail:
[email protected]
Editor—We thank Drs Robin and Alexander for their interest in our article1 and for extending the discussion to other agents which have been proven to be effective in reducing suxamethonium-induced rise in IOP. Although there was no report of vitreous extrusion that can be attributed solely to the use of suxamethonium,7 there is a growing consensus to limit its use in open globe injuries to difficult airway cases with salvageable eye situations. In such situations, as mentioned in our manuscript, several
doi:10.1093/bja/aen225
Editor—We read the article by Mowafi and colleagues1 with interest. Although the clinical risk of administering suxamethonium chloride for patients with open eye injuries has been questioned, strategies for reducing this rise in associated intraocular pressure (IOP) have been published.2 3 The authors in their discussion barely touched on the use of opioids with no mention of remifentanil. Several studies have now been published where researchers have demonstrated the successful obtunding of the rise in IOP associated with the administration of suxamethonium in adults and children.4 – 6 A bolus dose of remifentanil .0.5 mg kg21 has been shown to be as effective as larger doses of alfentanil.6 One advantage of using this opioid is its very short half-life compared with fentanyl and alfentanil. We do not think a discussion of the management of this potential clinical problem is complete without the mention of remifentanil. J. Robin* R. Alexander Worcester, UK *E-mail:
[email protected]
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Remifentanil obtunds intraocular pressure rises associated with suxamethonium
Correspondence
H. A. Mowafi* N. Aldossary S. A. Ismail J. Alqahtani Al-Khobar, Saudi Arabia *E-mail:
[email protected] 1 Mowafi HA, Aldossary N, Ismail SA, Alqahtani J. Effect of dexmedetomidine premedication on the intraocular pressure changes after succinylcholine and intubation. Br J Anaesth 2008; 100: 485 – 9 2 Vinik HR. Intraocular pressure changes during rapid sequence induction and intubation: a comparison of rocuronium, atracurium, and succinylcholine. J Clin Anesth 1999; 11: 95 – 100 3 Chiu CL, Jaais F, Wang CY. Effect of rocuronium compared with succinylcholine on intraocular pressure during rapid sequence induction of anaesthesia. Br J Anaesth 1999; 82: 757– 60 4 Alexander R, Hill R, Lipham WJ, et al. Remifentanil prevents an increase in intraocular pressure after succinylcholine and tracheal intubation. Br J Anaesth 1998; 81: 606 – 7 5 Ng HP, Chen FG, Yeong SM, Wong E, Chew P. Effect of remifentanil compared with fentanyl on intraocular pressure after succinylcholine and tracheal intubation. Br J Anaesth 2000; 85: 785– 7 6 Kaygusuz K, Toker MI, Kol IO, et al. The effects of different doses of remifentanil on intraocular pressure after tracheal intubation: a randomized, double-blind and prospective study. Ann Ophthalmol 2007; 39: 198 – 204 7 Chidiac EJ, Raiskin AO. Succinylcholine and the open eye. Ophthalmol Clin North Am 2006; 19: 279 – 85 8 Gerlach AT, Dasta JF. Dexmedetomidine: an updated review. Ann Pharmacother 2007; 41: 245 – 52
has been demonstrated.1 2 On the basis of these two papers, we evaluated the distance from the dura mater to the spinal cord by analysing the MRIs of 16 patients without spinal or medullary disease using the 1.5 T superconducting system (Gyroscan Intera, Philips Medical Systems, Best, The Netherlands). Measurements were made through sagittal spin-echo at the second, fifth, and 10th thoracic segments. Using the means of variation, no difference was found between interspaces T2 [3.59 (0.79) mm] and T10 [3.30 (0.78) mm] (P¼0.119). There was a significant difference between T5 and T2 (P¼0.001) and T5 [4.32 (1.1) mm] and T10 (P¼0.002). There was no evidence of correlation between the age and the measured distance between the dura mater and the spinal cord. There was evidence of correlation between the measurement at T2 and those at T5 (r¼0.8; P,0.001) and T10 (r¼0.6; P¼0.015). The longest distance between the dura mater and the spinal cord was at the fifth thoracic segment (Fig. 1). The calculated entry angle for a needle at T5 was 608. By our calculations, the distance from the entry point of the needle at an angle of 608 at T5 would double the distance to obtain cerebral spinal fluid when compared with a 908 angle at L3/L4 to 8.64 (2.2) mm. As the distance from the dura mater until the spinal cord at T5 is greater than at L1/L2, the 608 angle could increase the safety. On the basis of these evaluations of T2, T5, and T10, we believe that the introduction of the needle in an acute angle (608) may give greater safety for thoracic spinal anaesthesia.
doi:10.1093/bja/aen226
Magnetic resonance imaging of the spinal column Editor—Recently, the safe use of segmental spinal anaesthesia at T10 by using the combined spinal – epidural technique
Fig 1 Magnetic resonance imaging spinal column.
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strategies, including pretreatment with narcotics, can be used to blunt suxamethonium, laryngoscopy, and intubation-induced increases in IOP. Remifentanil is one of the narcotics which have been found beneficial in this respect.4 – 6 Remifentanil, however, in common with other narcotics, produces dose-dependent respiratory depression, hypotension, bradycardia, and muscle rigidity. Nausea and vomiting are also side-effects of importance after ophthalmic surgery, including open globe injury. Although the ultra-short half-life of the drug results in short-lived sideeffects, it may necessitate the administration of other opioids or neuromuscular blocking agents to prevent coughing which can result in increase in the IOP when the effect of suxamethonium wears off as recommended by Dr Alexander himself.4 Lastly, dexmedetomidine has, in addition to its analgesic and ocular hypotensive actions, sedative effects which make it suitable as premedication for ophthalmic surgery, particularly open eye injury.8
