Junichi Nishiyama

Use of perfusion index from pulse oximetry to determine efficacy of stellate ganglion block

Background Stellate ganglion block (SGB) is a widely used procedure for treatment of pain in the head and upper body, but the clinical signs used to verify the effectiveness of SGB can be ambiguous or variable in some patients. We observed the chronological changes in perfusion index (PI) from pulse oximetry to determine if these changes correlated with the clinical signs associated with an effective SGB. We hypothesized that PI could provide an easy method to assess the effectiveness of SGB. Method We compared the chronologies in PI on the treated and untreated sides of 21 patients in whom treatment by SGB was found to be effective. The SGB was performed by administering 6 mL of 1% mepivacaine. The effectiveness of the SGB was confirmed on the basis of clinical signs. Additionally, in two patients we tested whether increased PI on the treatment side correlated with increased microcirculation as measured by laser-Doppler blood flowmetry. Results On the side treated by SGB, PI increased 61.4% in the earlobe and 60.5% from baseline values in the upper limbs, at 5 minutes after initiation of the procedure. Differences in PI before and after treatment were significant at both sites. No time-course increases in PI were found on the untreated side at either site. Following SGB, increases in PI correlated with increases in blood flow as measured by laser-Doppler flowmetry. Conclusion PI increased in the earlobe and upper limbs on the treated side of 21 patients who received an effective SGB but not on the untreated side. The positive correlations between changes in PI and both presence of clinical signs and changes in blood flow in the skin microcirculation indicate a sympatholytic effect, suggesting that the PI could be useful in determination of the efficacy of SGB.

Development of a safe guidewire

As the result of a locking phenomenon that may occur in a guidewire inside a metal puncture needle when using the Seldinger technique to insert a central venous catheter, the guidewire can break and cause an embolism. To counter this possibility we devised a guidewire with a structure that made it difficult for locking to occur and compared it to conventional guidewires. Conventional guidewires are wound lengthways with a spring. The improved version has a special multi-ply structure. A series of 100 cases were divided into two groups: group A, the conventional guidewire group; and group B, the improved guidewire group. We punctured the internal jugular vein and attempted insertion of the guidewire through the side hole of a 22-gauge metal needle. We then compared the frequency of locking and the frequency of bending of the guidewire tips that have been withdrawn. In group A, locking occurred in 72% of the cases where the guidewire was unable to be inserted, but this figure was 0% in group B. The improved guidewire has the advantage of reducing the risk of locking and of guidewire breakage.

Effect of Power Crisis Caused By Earthquake on Operating Room Environment

The Great East Japan Earthquake in 2011 caused unprecedented damage to Japan and blasted the myth of safety at nuclear power plants. Electric power in Japan has yet to be completely restored. The suspension of air conditioning in operating rooms stemming from power blackouts hampers the ability to adjust room temperature and humidity levels and suspends ventilation through air cleaning filters. In this work, we used simulations to investigate the effect of changes in an operating room environment as a result of air conditioning suspension. We prepared two rooms, one equipped with an LED shadowless lamp and the other with a xenon gas lamp, suspended the air conditioning, and measured the changes in temperature, humidity, and air cleanliness on operating tables and in the entire rooms. The physical impressions of four staff members working in each room were also collected. Results showed that, after suspension of the air conditioning, the temperature on the operating table increased by 11.8°C in the LED room and by 26.2°C in the xenon gas room. The overall temperature in both rooms increased by 2-3°C. Although the humidity on the operating table in both rooms decreased, it increased in the entire room by 10-12% in both rooms. As for the physical impressions of the staff, in the LED room, half complained of the heat while working, and in the xenon gas room, all complained of damp heat affecting their work. Air cleanliness surpassed the designated level within 8 and 22 minutes of suspension of air conditioning in the LED and xenon gas rooms, respectively. After that, particles continued to increase and surpassed 35,000/ft3 in both rooms. These results demonstrate that the suspension of air conditioning in operating rooms rapidly degrades the working environment, thus increasing the risk of surgical site infection.

Unexpected difficult intubation owing to a tracheal web in a patient with past history of a Fontan procedure

To the Editor: Acquired tracheal web is a rare late complication of tracheal intubation and is formed during the development of a laryngeal granuloma [1]. We report an unexpected case of tracheal web encountered after induction of general anesthesia. A 24-year-old male patient (height 168 cm, body weight 52 kg) with acute cholecystitis was scheduled to undergo laparoscopic cholecystectomy. His medical history included transposition of the great arteries, modified Fontan surgery at 6 years of age, and Fontan surgery at 23 years of age, in which he had had postoperative intubation with an 8.5-mm internal diameter (ID) tube for less than 24 h. He had no respiratory symptoms. His physical status was American Society of Anesthesiologists (ASA) performance status (PS) III. After anesthesia was induced and muscle relaxation was achieved, tracheal intubation was attempted. The Cormack grade of the glottic view was I and a subglottic tracheal web was observed (Fig. 1a). Because tracheal intubation with 8.0-, 7.5-, and 7.0-mm ID tubes was impossible owing to resistance, the cholecystectomy was cancelled. The tracheal intubation was needed for transesophageal echocardiography (TEE) monitoring, in the event of acute heart failure caused by pneumoperitoneum—a risk for patients with a history of Fontan procedure. Otolaryngologists examined the larynx using a flexible fiberscope, and laryngomicrosurgery was planned for the following day. Under anesthesia, tracheal intubation was performed with a 6.0-mm ID tube inserted above the web, using a tracheal tube introducer (15 Fr, Portex, Kent, UK). The tracheal web was visualized using a direct laryngoscope (Fig. 1b) and was removed using microscissors. Postoperatively, beclomethasone inhalation was administered and no glottal swelling was found. Fibrotic tissue was found on pathological examination. The cholecystectomy was performed 6 days after the laryngomicrosurgery. Under anesthesia, an 8.0-mm ID tube was inserted without resistance. A FloTrac sensor and PreSep central venous catheter (Edwards Lifesciences, Irvine, CA, USA) were used for circulatory management in the event of acute heart failure and TEE was used for cardiac monitoring. Instead of laparoscopic surgery, open surgery was performed, owing to adhesions. Vital signs remained stable during the operation and postoperative tracheal tube extubation was uneventful. Tracheal webs are late and rare sequelae of tracheal intubation and tracheotomy. Neck extension, and the prone and lateral positions, a larger tracheal tube, and a prolonged intubation period tend to increase the incidence of tracheal webs [1]. The mean duration of tracheal intubation was 5.2 days in patients with a laryngeal granuloma at the cuff site [1], and there is one report of a tracheal web in a patient under mechanical ventilation for a month [2]. While many patients with tracheal web have asthma or chronic obstructive pulmonary disease [3] others have no respiratory symptoms [2]. According to the algorithm for management, the first choice for patients without respiratory symptoms is conservative treatment, and for patients J. Ajimi (&) J. Nishiyama A. Ando T. Suzuki Department of Anesthesiology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan e-mail: ajimi@is.icc.u-tokai.ac.jp