Recurrent postoperative deep vein thrombosis in a patient with

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J Clin Anesth 2007. (in press). Recurrent postoperative deep vein thrombosis in a patient with ... The diagnosis of OSA had been made based on sleep studies.
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4 FIGURE Lar yngeal view obtained from the Air wayScope during extubation 1) The vocal cords and endotracheal tube prior to extubation. 2) Post-extubation, the vocal cord appearance using the Air wayScope with breath holding. 3) Vocal cord appearance using the Air wayScope during deep inhalation.

respiratory maneuvers displayed on the sleeve monitor connected to the AWS could be seen simultaneously by the anesthesiologist and surgeon. The patient was discharged from the operating room without reporting any pain or discomfort. This case highlights several advantages of the AWS to assess vocal cord function. First, because the CCD camera is located 2.5 cm from the glottis, an unobstructed, clear glottic view is obtained. Second, several observers can watch the procedure simultaneously. Third, re-intubation, if necessary, can be performed very easily with the tube set in the channel just 3 cm proximal to the glottis. Finally, since the Pblade® is anatomically shaped, the procedure is easily tolerated by the patient, as minimal lifting force is required to expose the glottis. As this device is used for intubation when the patient is conscious,5 it is considered to be less invasive during extubation, requiring minimal sedation. We conclude that the AWS is a useful device to evaluate vocal cord function at the time of tracheal extubation. Chika Kikuchi MD Akihiro Suzuki MD PhD Hiroshi Iwasaki MD PhD Asahikawa Medical College, Hokkaido, Japan E-mail: [email protected] Accepted for publication September 11, 2007. References 1 Koyama J, Aoyama T, Kusano Y, et al. Description and first clinical application of AirWay Scope for tracheal CAN J ANESTH 54: 12

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intubation. J Neurosurg Anesthesiol 2006; 18: 247– 50. Hirabayashi Y. Airway Scope®: initial clinical experience with novice personnel. Can J Anesth 2007; 54: 160–1. Suzuki A, Toyama Y, Katsumi N, et al. The PentaxAWS® improves laryngeal view compared with Macintosh blade during laryngoscopy and facilitates easier intubation (Japanese). Masui 2007; 56: 464–8. Suzuki A, Hayashi D, Toyama H, Minami S, Iwasaki H. Use of the Pentax-AWS® in a patient with Cormack 3a difficult airway (Japanese). Masui 2007; 56: 341–4. Suzuki A, Kunisawa T, Takahata O, Iwasaki H, Nozaki K, Henderson JJ. Pentax-AWS® (Airway Scope) for awake tracheal intubation (Letter). J Clin Anesth 2007 (in press).

Recurrent postoperative deep vein thrombosis in a patient with obstructive sleep apnea and malignant hyperthermia susceptibility To the Editor: We recently managed a patient with known malignant hyperthermia susceptibility (MHS) who had a concurrent history of obstructive sleep apnea (OSA), recurrent deep vein thrombosis (DVT) and past history of pulmonary thromboembolism (PTE). A 67-yr-old male (ASA physical status III) was diagnosed with adenocarcinoma of the sigmoid colon and was scheduled to undergo anterior resection. In the past, he had had three uneventful general anesthetics for unrelated surgeries, but on each occasion had developed bilateral leg DVT and documented PTE once. Since then he was on prophylactic anticoagulation with dalteparin sodium 11,000 IU sc bid. The diagnosis of OSA had been made based on sleep studies. Because of a family history of unexplained death under anesthesia, he had undergone in vitro testing and a diagnosis of MHS was confirmed. His grandmother had died unexpectedly during an operation many years before and this had prompted the testing. To facilitate epidural catheter insertion for this surgery, anticoagulation had been omitted the evening before. In the operating room, recommended MH preparations and precautions were taken and intravenous access and monitoring were instituted. An epidural catheter was inserted at T9/10 without complication and appropriately tested. After preoxygenation, anesthesia was

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induced and maintained intravenously with fentanyl and propofol. Neuromuscular blockade facilitated controlled ventilation with air-oxygen. Surgery lasted three hours and was uneventful. All monitored parameters (including nasopharyngeal core temperature and end-tidal expired CO2) were within normal limits throughout. After tracheal extubation, the patient was transferred to the postanesthetic care unit (PACU) where the epidural infusion of 0.25% ropivacaine and 0.05 mg·mL–1 hydromorphone was continued. The patient had an uneventful stay in PACU and then in the critical care unit, with the epidural providing effective analgesia. On the first postoperative day, the acute pain service (APS) anesthesiologist and nurses evaluated the patient. There was no evidence of respiratory compromise related to his OSA. Another evaluation by the dedicated thromboembolic (TE) team revealed that he had developed bilateral DVT. Following consultations with the TE specialists, surgeons, critical care physicians and the APS anesthesiologist, a decision was made to resume anticoagulation. The patient’s epidural catheter was removed and he was started on intravenous hydromorphone patient-controlled analgesia and a multi-modal adjuvant analgesic regime. According to standard guidelines, dalteparin 5000 IU sc bid was initiated. This dose was escalated over the next three days to 11,000 IU bid to match the preoperative dosing schedule. He made satisfactory recovery without untoward incident or event, and was discharged from hospital on the fifth postoperative day. This case represents an uncommon combination of significant risk factors for anesthesia and surgery. The perioperative management of MH has been the subject of much interest amongst anesthesiologists.1 With the added history of OSA and recurrent DVT/PTE, this patient’s perioperative care had multiple objectives. Epidural anesthesia was clearly of benefit to a patient with OSA, DVT/ PTE and MH-S.2–4 The conflict of this plan was with the patient’s anti-coagulation therapy - preoperative cessation of anticoagulation was required to permit safe epidural catheter insertion and ensure surgical hemostatis. This led to the anticoagulants being withheld for a period of almost 24 hr. It is uncertain how this may have contributed to the recurrence of DVT. Even though epidural analgesia is well known to attenuate the hypercoaguable response to surgery and reduce the risk of development of lower limb DVT,3 it is unclear whether this would have provided the same protection as pharmacologic DVT prophylaxis with low molecular weight heparin. Adjuncts to DVT prophylaxis, anti-thromboembolic stockings and pneumatic intermittent calf compression devices could have been considered.5 Single-shot intrathecal or epidural techniques with opioid analgesics may also allow for CAN J ANESTH 54: 12

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continued anti-coagulation while providing adequate analgesia after abdominal surgery for up to 48 hr.6,7 Our experience from this case suggests that in patients with recurrent DVT/ PTE, avoiding changes in stable anti-coagulation regimens may be a priority. Further evidence is required in high-risk patients to balance the benefits of epidural analgesia (that would require cessation of anticoagulation) against the risks of recurrence of DVT. Colin Sinclair MB FRCA Naveen Eipe MBBS MD Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada E-mail: [email protected] Conflicts of interest and sources of support: None declared. Accepted for publication September 17, 2007. References 1 Schonell LH, Sims C, Bulsara M. Preparing a new generation anaesthetic machine for patients susceptible to malignant hyperthermia. Anaesth Intensive Care 2003; 31: 58–62. 2 Boushra NN. Anaesthetic management of patients with sleep apnoea syndrome. Can J Anaesth 1996; 43: 599–616. 3 Ganapathy S, Buckley DN. Best evidence in anesthetic practice. Prevention: intraoperative neuraxial blockade reduces some postoperative complications. Can J Anesth 2001; 48: 990–2. 4 Saito O, Yamamoto T, Mizuno Y. Epidural anesthetic management using ropivacaine in a parturient with multi-minicore disease and susceptibility to malignant hyperthermia. J Anesth 2007; 21: 113. 5 Geerts W, Ray JG, Colwell CW, et al. Prevention of venous thromboembolism. Chest 2005; 128: 3775–6. 6 De Pietri L, Siniscalchi A, Reggiani A, et al. The use of intrathecal morphine for postoperative pain relief after liver resection: a comparison with epidural analgesia. Anesth Analg 2006; 102: 1157–63. 7 Gambling D, Hughes T, Martin G, Horton W, Manvelian G. A comparison of Depodur, a novel, single-dose extended-release epidural morphine, with standard epidural morphine for pain relief after lower abdominal surgery. Anesth Analg 2005; 100: 1065–74.