Predicting the optimal minimal cuff volume of the laryngeal mask airway from physical examination parameters

BACKGROUND: Head and neck anatomy affects the laryngeal mask airway (LMA) cuff volume. The purpose of this study was to identify physical parameters that can be standardized to predict LMA cuff volume and measure the optimal and minimal LMA cuff volume in adults. METHODS: The predictors of volume or pressure of the LMA cuff were investigated in 167 patients. Manufacturers recommend a maximal cuff pressure (MCP) (i.e., 40 ml for size 5, 30 ml for size 4), an optimal cuff volume (OCV) at a cuff pressure of 60 cmH2O, and a minimal cuff volume (MCV) just before audible air leakage. The physical parameters measured included height, weight, body mass index, modified Mallampati classification (MMP), neck circumference, neck length, and thyro-mental distance. Data were analyzed by stepwise multilinear analysis. RESULTS: The regression equations (REs) were as follows: OCV (1.2 + [0.1 × height] + [0.5 × neck length]); MCV for men (−35.7 + [0.25 × height] + [0.7 × neck length] − [4.1 × MMP]); and MCV for women (−42.5 + [0.27 × height] + [0.75 × neck length] − [2.5 × MMP]). The mean values were as follows: MCP > 200 cmH2O, minimal cuff pressure < 20 cmH2O, OCV of 24.7 ml for men and 15.9 ml for women, and MCV of 12.1 ml for men and 7.1 ml for women. CONCLUSIONS: LMA cuff volume is estimated from the patient's height, neck length, and MMP. The RE for calculating the MCV shows a high correlation with height, neck length, and MMP.

Predicting the optimal minimal cuff volume of the laryngeal mask airway from physical examination parameters

BACKGROUND: Head and neck anatomy affects the laryngeal mask airway (LMA) cuff volume. The purpose of this study was to identify physical parameters that can be standardized to predict LMA cuff volume and measure the optimal and minimal LMA cuff volume in adults. METHODS: The predictors of volume or pressure of the LMA cuff were investigated in 167 patients. Manufacturers recommend a maximal cuff pressure (MCP) (i.e., 40 ml for size 5, 30 ml for size 4), an optimal cuff volume (OCV) at a cuff pressure of 60 cmH2O, and a minimal cuff volume (MCV) just before audible air leakage. The physical parameters measured included height, weight, body mass index, modified Mallampati classification (MMP), neck circumference, neck length, and thyro-mental distance. Data were analyzed by stepwise multilinear analysis. RESULTS: The regression equations (REs) were as follows: OCV (1.2 + [0.1 × height] + [0.5 × neck length]); MCV for men (−35.7 + [0.25 × height] + [0.7 × neck length] − [4.1 × MMP]); and MCV for women (−42.5 + [0.27 × height] + [0.75 × neck length] − [2.5 × MMP]). The mean values were as follows: MCP > 200 cmH2O, minimal cuff pressure < 20 cmH2O, OCV of 24.7 ml for men and 15.9 ml for women, and MCV of 12.1 ml for men and 7.1 ml for women. CONCLUSIONS: LMA cuff volume is estimated from the patient's height, neck length, and MMP. The RE for calculating the MCV shows a high correlation with height, neck length, and MMP.

Postoperative respiratory difficulty due to asymptomatic anterior cervical osteophyte after brain tumor surgery: a case report / 대한마취과학회지

Anterior cervical osteophytes are commonly found in elderly patients, but rarely produce symptoms. When symptoms occur, they can range from mild symptoms of dysphagia, dysphonia, and foreign body sensation to severe symptoms of airway obstruction due to compression of the pharynx or larynx. We report the case of a 59-year-old man who underwent brain tumor surgery, and developed post-operative respiratory difficulty due to progressive pharyngo-laryngeal edema, requiring urgent endotracheal intubation, secondary to the presence of a previously asymptomatic anterior cervical osteophyte. It is paramount to recognize that asymptomatic anterior cervical osteophytes are a potential cause of life-threatening post-operative respiratory complications that can rapidly progress to life-threatening airway obstruction after surgeries in the prone position, especially in elderly patients.

In-plane three-step needle insertion technique for ultrasound-guided continuous femoral nerve block after total knee arthroplasty: a retrospective review of 488 cases / 대한마취과학회지

BACKGROUND: Continuous femoral nerve block (CFNB) improves postoperative analgesia after total knee arthroplasty (TKA). The aim of this study was to investigate the clinical efficacy and complications of our in-plane three-step needle insertion technique that was devised to reduce the risk of direct femoral nerve injury during CFNB in anesthetized patients. METHODS: This retrospective study included 488 patients who had undergone TKA. Ultrasound (US)-guided CFNB was performed under general or spinal anesthesia using an in-plane, three-step needle insertion technique. The success rate and difficulties of catheter placement, clinical efficacy of analgesia, and complications were recorded. RESULTS: Femoral catheters were placed with a 100% success rate. In 488 patients, real-time US imaging revealed easy separation of the fascia iliaca and the femoral nerve following injection of local anesthetic through a Tuohy needle. Verbal numerical rating scale pain scores (0–10) were 2.0 ± 1.2, 3.5 ± 1.9, 3.2 ± 1.7, 2.9 ± 1.3, and 2.5 ± 1.1 at 1, 6, 12, 24 and 48 h postoperatively. No femoral hematoma, femoral abscess, or neurologic complications, including paresthesia or neurologic deficits, were observed during the 8-week follow-up period. CONCLUSIONS: This retrospective study suggests that an in-plane three-step needle insertion technique for CFNB may reduce the risk of femoral nerve injury in anesthetized patients.

Operation room management in Korea: results of a survey / 대한마취과학회지

BACKGROUND: The current state of general hospital operation room (OR) in Korea and how these ORs are being operated remain unclear. Therefore, the aim of this study was to investigate and assess the current state of OR management and surgical scheduling in general hospitals of Korea. METHODS: A total of 92 anesthesiology training hospitals and 2 equivalent hospitals in Korea were targeted for the survey. Anesthesiologists in hospitals received questionnaires for OR, anesthetic managements and surgical scheduling directly or by phone from the beginning of October 2015 to the end of December 2015. RESULTS: Of the 94 hospitals that were targeted, 59 hospitals (62.7%) responded to the survey. Of the 59 hospitals, 40 (67.8%) had 500–1,000 beds, 36 (61.0%) had 11–20 ORs. Most OR arrangements were made by residents and specialists in Anesthesiology Department (90%). Most hospitals (47.4%) in the response set performed total surgeries in the range of 10,000 to 20,000 annually. The proportion of emergency surgeries in the total surgeries was 2.8–55.0%. Methods for predicting expected surgery time were arbitrarily decided by surgeons (61%), anesthesiologist's experience (20%), or by analyzing historical data using software (5%). CONCLUSIONS: This survey study could trigger active operational researches for OR efficiency. It might help hospital policy makers manage OR resources more efficiently.