Myung-Soo Jang

Dexmedetomidine promotes the recovery of the field excitatory postsynaptic potentials (fEPSPs) in rat hippocampal slices exposed to oxygen-glucose deprivation.

Dexmedetomidine (DEX), a selective α2 adrenergic agonist, is an anesthetic and sedative agent, and is reported to exert neuroprotective effects after hypoxic ischemia. However, there are few studies on the electrophysiological effect of DEX in hippocampal slices under ischemic conditions. The effects of DEX on field potential in hippocampal slices exposed to oxygen-glucose deprivation (OGD) were evaluated. Hippocampal slices were prepared from rats, and the evoked field excitatory postsynaptic potentials (fEPSPs) were recorded using the MED 64 system. Hypoxic-ischemia was induced by perfusion with glucose-free artificial cerebrospinal fluid (aCSF) bubbled with 95% N2 and 5% CO2, and hippocampal slices were perfused with DEX-added aCSF before, during, and after OGD induction. In the normal hippocampal slices, perfusion with 1 and 10μM DEX did not significantly decrease the normalized fEPSP amplitude, but 100μM DEX significantly reduced the fEPSP amplitude compared with its baseline control. The induction of OGD remarkably decreased the fEPSP amplitude, whereas the pre-, co-, and post-treatment of 10μM DEX gradually promoted recovery after washing out, and consequently the amplitude of fEPSP in DEX pre-, co-, and post-treated OGD slices were significantly higher than that in the untreated OGD slices at 10min and 60min after washing out. In particular, co-treatment with DEX conspicuously promoted the recovery of the fEPSP amplitude at the beginning of washing out. These results suggest the possibility of DEX as a therapeutic agent to prevent hypoxic-ischemic brain damage and promote functional recovery after ischemia.

General anesthesia for a patient with multiple system atrophy.

Multiple system atrophy (MSA) is a rare, adult-onset neurodegenerative disease [1]. Two clinical features characterize MSA: motor features and autonomic dysfunction [2]. During anesthesia, regulation of cardiovascular instability is an important issue. We report a case of successful general anesthesia in a MSA patient. A 66-year-old man (170 cm, 40 kg) presented for a laparoscopic hemicolectomy. Recent intermittent hematochezia suggested rectal cancer. MSA was diagnosed at age 56, and rapid progression left him bedridden. His past medical history included diabetes and hypertension. Preoperatively, no abnormal finding was detected on a laboratory examination, chest X-ray, or electrocardiography. In operating room, routine monitoring devices for electrocardiography, pulse oximetry, and non-invasive blood pressure, and a noninvasive cardiac output monitor showing cardiac output, cardiac index (CI), and stroke volume variation (SVV) were set up. To address possible cardiovascular instability, arterial cannulation was performed before anesthesia. A central venous catheter has already been inserted through the subclavian vein. Initial bispectral index (BIS) was 87, blood pressure (BP) 150/60 mmHg, heart rate (HR) 75 beats/min, central venous pressure (CVP) 3 cmH2O, CI 2.4 L/min/m2, and SVV 10%. General anesthesia was induced with etomidate 0.4 mg/kg intravenously. With good mask ventilation, 40 mg of rocuronium was injected intravenously, and we tried laryngoscopic intubation. Because of poor mouth opening even after full relaxation with the rocuronium, moving the laryngoscope forward was impossible. So, we performed a bronchoscopic intubation. Anesthesia was maintained with sevoflurane 1.5-2 vol% and intravenous remifentanil 0.05 µg/kg/min in an O2-air mixture at a 1 : 1 ratio. The operation lasted about 4 h and anesthesia was maintained appropriately with BIS at 35-50. At 25 min after induction of anesthesia, the BP abruptly fell from 160/85 to 80/50 mmHg. This was managed successfully with rapid fluid administration and a phenylephrine bolus dose of 40 µg intravenously. HR hardly changed, from 82 to 90 beats/min. However, systolic blood pressure dropped again to 80 mmHg during awakening despite the irritating sensation of the endotracheal tube. Phenylephrine 20 µg raised the BP to 100/60 mmHg again with little change in HR, 70-75 beats/min (Fig. 1). Finally, gentle extubation was tried, and no respiratory event occurred. He was transferred to the surgical intensive care unit, and has been cardiovascularly stable since then. He was returned to the ward next day. Fig. 1 Hemodynamic changes during anesthesia. (A) Indicates the changes in blood pressure and heart rate. There is an abrupt decrease in blood pressure to 80/50 mmHg at 25 min after induction, but almost no change in the heart rate. Similarly, a sudden drop ... The annual occurrence of MSA among those over 50 is ~3 per 100,000 with no gender predilection [1,2,3]. Currently, no definite diagnostic criteria or therapies exist, beyond supportive care [2]. There are several considerations regarding anesthesia in MSA. First, the anesthesiologist should be concerned about sudden hypotension due to dysautonomia. Several authors have reported that regional anesthesia is better than general anesthesia in maintaining cardiovascular stability in MSA because of absence of procedures that may aggravate hypotension, such as positive-pressure ventilation, and the avoidance of anesthetics for maintenance [3]. Nevertheless, there is no evidence that regional anesthesia is necessarily the right answer in MSA patients. In contrast, Cohen [1] reported a successful case of general anesthesia after failure of epidural anesthesia, induction with thiopental and succinylcholine, and maintenance with N2O and methoxyflurane. Ketamine was reported as a successful anesthetic in a MSA patient without hypotension in 1983 [4], because ketamine causes central sympathetic stimulation primarily through parasympathetic inhibition. We decided on general anesthesia for several reasons: noncooperation, the possibility of procedural failure due to involuntary movements, and regional anesthesia not being suitable for laparoscopic surgery. The preoperative hemodynamic state of our patient was stable; however, realizing that MSA patients have a damaged sympathetic system, we decided to use etomidate with its minimal cardiovascular effects. We also used remifentanil, which has been reported to effectively suppress cardiovascular reactions and myoclonus after endotracheal intubation with etomidate [5]. Moreover, in MSA patients, bilateral vocal cord paralysis can be a life-threatening complication [1,2]. This adverse event can be aggravated during the induction or post-extubation period due to several stimuli, such as tracheal intubation under insufficient depth of anesthesia or unnecessary suction during extubation. If a preoperative evaluation is impossible, preventative measures should be used. Although no case has been reported of awake bronchoscopic intubation in MSA patients, it is worth considering in patients who are suspected to have difficult airways if the patients are cooperative. We also prepared an emergency cricothyroidotomy kit; the anesthesiologist should always be ready for an emergency tracheostomy situation. In conclusion, anesthesia in MSA remains a great challenge due to the many potential complications. Anesthesiologists should consider the condition of patients with MSA and carefully decide on the appropriate method of anesthesia for the type of operation.

Age and Gender Are Important Considerations in Choosing the Sniffing Position for Laryngoscopic View

Aims: The sniffing position is considered to be the standard position for direct laryngoscopic viewing. This crossover study evaluated age and gender as variables in comparing the benefits of the sniffing position over simple head extension for laryngeal view during direct laryngoscopy. Methods: Laryngoscopy with a curved blade was performed on 200 anesthetized adults (100 males, 100 females) presenting for routine elective surgery. Glottic visualization was assessed by using the percentage of glottic opening (POGO) score in both simple extension and sniffing positions without the aid of the assistant or external laryngeal manipulation. Each gender group was divided into a younger group (< 50 years) and an older group (≥ 50 years). POGO scores were compared between both positions within each group. Results: Mean (SD) POGO scores increased significantly only in younger male patients from 43% (39%) in the head extension position to 76% (30%) in the sniffing position. Conclusion: The sniffing position seems to be advantageous for getting a better laryngeal view during laryngoscopy for tracheal intubation in adult male patients less than 50 years old.

Biting of the Tongue in a Patient with a Tracheostomy during Surgery in the Supine Position.

Biting of the tongue is an unfamiliar perioperative event. However, this complication can occur under some situations such as spinal surgeries with the patient in the prone position3), epileptic seizures6), and rarely in accidental trauma. A bitten tongue may lead to various outcomes ranging from simple laceration to upper airway obstruction by macroglossia or necrosis requiring amputation2). A 24-year-old female was scheduled for cranioplasty. She was delivered to the operating room with stuporous mentality, but was able to breathe spontaneously through the tracheostomy tube. Routine monitorings including ECG, SPO2, EtCO2 and blood pressure were carried out. General anesthesia was induced using 80 mg intravenous propofol and 40 mg rocuronium and was maintained with 1.5-2 vol% sevoflurane and 0.05-0.1 mcg/kg/min remifentanil in an O2-air mixture at a 1 : 1 ratio. The tracheostomy tube was changed for hygienic purposes and connected to a ventilator machine after endotracheal and intraoral cavity suction. The operation lasted about four hours and was uneventful. All the anesthetics were stopped and muscle relaxation was reversed with the administration of glycopyrrolate and pyridostigmine. Her mouth was open less than 1 cm and her tongue was not protruded. She responded gradually upon exposure to verbal and tactile stimuli with the recovery of spontaneous breathing. Suddenly, she bit the anterior third of her tongue and continued to do so more violently as time passed; cyanotic and edematous changes were noted (Fig. 1). At first, we thought she would quit biting her tongue as she would recover from anesthesia further. Then, we decided to withhold giving any anesthetics or neuromuscular blocking agents. Though we attempted to open her mouth manually as safely as possible, the mandible could not be pulled down and we were unable to retract the tongue from her teeth. Further complicating matter was our inability to communicate with this mentally altered patient. There was no space in which to put fingers or a tongue compressor into her mouth. Unfortunately, she continued to bite her tongue harder and marked color changes and bleeding were observed. Although we began to increase the sevofluorane concentration, her jaw muscle did not relax sufficiently to allow us to gain access to her oral cavity, and finally we injected 50 mg succinylcholine intravenously about 3 minutes later. Seconds later, her chin relaxed and her tongue retracted. The color of her tongue gradually returned to normal. After confirming that there was no active bleeding, saline irrigation and wet gauze were applied to the wound. An oral airway was inserted and fixed with tape to ensure it would not be spit out unconsciously. She transferred to recovery room, no other events were observed. Several hours later, the tape and oral airway were removed. Fig. 1 Self-biting injury to the anterior third of tongue during recovery of anesthesia. Tracheostomy is the most common procedure for patients with pulmonary problems or those requiring respiratory support in the neurosurgical field4). Biting of the tongue is a rare complication under general anesthesia, especially in patients with a tracheostomy. However, several cases have been reported in association with the prone position during surgery without a bite blocker1), prolonged re-insertion of dentures in patients without teeth5). and eclamptic seizures. Our case indicates that a patient can bite their tongue even when in a supine position without orotracheal intubation, particularly in patients with brain damage. Although we did not figure out using airway opening instruments such as screw-type or Heister mouth gag in the event, those seem to be a good method of choice worth to be tried in suitable cases. Furthermore, clinicians should seriously consider the routine use of an oral airway in patients with a tracheostomy. One thing that we should keep in mind is that manual attempts to open the mouth carelessly can bring about injuries to the practitioner as well as the patient. Neurosurgeons and anesthesiologists should be aware of the possibility of tongue protrusion and subsequent biting in patients with a tracheostomy.

Association Between Arterial Carbon Dioxide Tension and Outcome in Patients Admitted to the Intensive Care Unit After Coronary Artery Bypass Surgery

OBJECTIVES The aim of this study was to determine the association between PaCO2 and patient outcome in patients admitted to the intensive care unit (ICU) after coronary artery bypass grafting (CABG). DESIGN A retrospective cohort study. SETTING Single-institutional, university hospital. PARTICIPANTS All patients admitted to the ICU after CABG between January 2009 and December 2012. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Based on PaCO2 status during the first 24 hours after CABG, 1,011 patients were classified into 4 groups: normocapnia, hypocapnia, hypercapnia, and dual hyper/hypocapnia. The 30-day mortality rate was 0.7% (n = 4) for normocapnia, 1.5% (n = 4) for hypocapnia, 2.2% (n = 3) for hypercapnia, and 7.5% (n = 4) for the dual-exposure group. The extubation times were 13.3±21.7 hours, 15.8±21.37 hours, 21.79±39.70 hours, and 42.29±75.35 hours, respectively. After adjusting for confounding variables, the dual hypocapnia and hypercapnia exposure group was associated with increased 30-day mortality (odds ratio [OR] = 8.08; 95% confidence interval [CI], 1.82-35.86; p = 0.006) and delayed extubation (OR = 2.40; 95% CI, 1.24-4.64; p = 0.010). CONCLUSIONS Exposure to both hypocapnia and hypercapnia within 24 hours after CABG was associated independently with increased risk of 30-day mortality and delayed extubation. Exposure to either hypocapnia or hypercapnia alone was not associated with patient outcome.

Endotracheal tube intubation with the aid of a laryngeal mask airway, a fiberoptic bronchoscope, and a tube exchanger in a difficult airway patient -a case report-

A 28-year-old male patient with occipito-atlanto-axial instability underwent a cervical fusion with posterior technique. Post-operatively, the endotracheal tube (ETT) was removed, and the patient was transferred to the intensive care unit. After transfer, an upper airway obstruction developed and reintubations with a laryngoscope were attempted but failed. We inserted a #4 proseal laryngeal mask airway (LMA) and passed a 5.0 mm ETT through the LMA with the aid of a fiberoptic bronchoscope. We passed a tube exchanger through the 5.0 mm ETT and exchanged it with a 7.5 mm ETT. This method may be a useful alternative for difficult tracheal intubations.

Experience of atypical chest pain that can be overlooked and neglected in youths.

To the Editor: Chest pain in the young can be a diagnostic challenge to physicians. Although adolescents scarcely have heart-origin problems, meticulous examination is important to rule these out thoroughly [1]. Sometimes, physical examination and history taking, rather than complicated laboratory tests, give an answer. A 17-year-old girl visited our hospital because of intermittent sharp and brief left chest pain. It had started 10 days previously, and she pointed out the site well with her finger tips. The attack came during inspiration, so she breathed shallowly. The pain lasted approximately 3–15 min and completely resolved without medication. With left pneumothorax 2 weeks before visiting, she recovered with oxygen supply therapy. No abnormal findings were detected by physical examination, electrocardiography, or chest X-ray. Once we assumed the pain was rarely related to heart, myofascial trigger point injection was performed. We performed an intercostal nerve block at 3 levels on her left anterior chest. Unexpectedly, this seemed to have hardly any effect on relieving her pain. Later, we heard she experienced the pain again on her way to school and, separately, at the school. We considered the features of her pain were benign and were derived from the parietal pleura, and finally diagnosed the problem the precordial catch syndrome. Unfortunately, since Miller and Texidor first described PCS in 1955 [1], precordial catch syndrome (PCS) has long been under-recognized among physicians. PCS commonly occurs at age 6–12 years with no sex predominance. The pain is sharp, brief, knifelike, and easily located with the finger, commonly at the left sternal border, over an intercostal space [2]. More exclusively, the attack is aggravated by inspiration only, so patients breathe shallowly. The episode usually lasts from 3 to 30 min, and complete pain relief comes spontaneously. Most of these patients are basically healthy [1, 3]. One study evaluated the causes of chest pain of 380 children. Interestingly, only 0.3 % had a cardiac origin and 1.1 % had abnormal electrocardiogram. Approximately 15 % were miscellaneous disorders, for example PCS. As a result, meticulous history taking and physical examination are sufficient to diagnose PCS. It seems unnecessary to conduct complicated laboratory tests, for example complete blood count, electrocardiogram, chest X-ray, and echocardiogram [2]. To diagnose the PCS, many other origins of chest pain must be ruled out on the basis of their distinct features (Table 1). So far, definitive treatment of PCS is unknown and there are no data for effectiveness of nerve block in PCS. We tried intercostal nerve block, expecting pain relief, however, that seemed to be ineffective for PCS. According to several reports, nerve block is not always effective to any pain. For example, greater occipital nerve block is ineffective in chronic tension type headache, and idiopathic persistent facial pain [4, 5]. Finally, we should consider nerve block as a new treatment for PCS more carefully. Further investigation is required to validate its effectiveness. M.-S. Jang Department of Anesthesiology and Pain Medicine, College of Medicine, Kyung Hee University, Seoul, Korea