Subjective and objective assessments of mental workload for UAV operations.

BACKGROUND: Unmanned Aerial Vehicles (UAVs) have created safety problems for the publics. Assessments of the mental workload for UAV operations are essential to realize the causes of UAV accidents. OBJECTIVE: To test the following hypotheses: i. mission difficulty in UAV operation affects both subjective and objective measures of mental workload; ii. mission difficulty affects number of failures in UAV operation. METHODS: Fourteen male adults participated as UAV operators after attending a UAV training course. They performed four flight missions of different difficulty levels. During their flight missions, their heart rate and inter-beat interval (IBI) were collected. Upon completing each flight mission, the participants gave subjective ratings of mental workload using three commonly adopted assessment tools. The time of flight and number of failures in flight operations were also recorded. RESULTS: The results showed that mission difficulty affected the scores of all three assessment tools significantly. Mission difficulty also affected number of failures and IBI significantly. The scores of the three assessment tools were highly correlated (ρ= 0.7 to 0.83, p < 0.001) with one another. The results of the three subjective ratings were also consistent with that of the IBI data. CONCLUSIONS: High mental workload in UAV operation could lead to poor flight performance.

Assessment of risk of tripping before and after crossing obstacles under dimmed lighting conditions.

BACKGROUND: Tripping and falling are common at work. Investigating the perceived risk of tripping is important for the safety of workers. OBJECTIVE: To test the hypotheses that the perceived risk of tripping is affected by obstacle depth, obstacle height, number of obstacle, and light location under dimmed lighting conditions. METHODS: A walkway with one to three obstacles in the middle was prepared. Each obstacle had a height of 0, 5, or 10 cm and a depth of 1 or 10 cm. The laboratory was dimmed with only one light either at the beginning, the midway, or at the end of the walkway. The perceived risk of tripping (PRT) was measured both before and after the participant walked through the walkway. A rating of gait disturbance (RGD) to each participant upon crossing the obstacle was also recorded. RESULTS: The PRT measured both before and after the walk were between "almost no" to "medium" risk levels. The RGD was affected significantly by the location of the light, obstacle height, obstacle depth, and number of obstacle. CONCLUSION: The location of light significantly affected the PRT both before and after the participants walked. The participants perceived a higher risk of tripping and had a relative high probability of foot-obstacle contact when the light was behind than when the light was in the front.

Paravertebral Block Plus Thoracic Wall Block versus Paravertebral Block Alone for Analgesia of Modified Radical Mastectomy: A Retrospective Cohort Study.

BACKGROUND AND OBJECTIVES: Paravertebral block placement was the main anesthetic technique for modified radical mastectomy in our hospital until February 2014, when its combination with blocks targeting the pectoral musculature was initiated. We compared the analgesic effects of paravertebral blocks with or without blocks targeting the pectoral musculature for modified radical mastectomy. METHODS: We retrospectively collected data from a single surgeon and anesthesiologist from June 1, 2012, to May 31, 2015. Intraoperative sedatives and analgesic requirements, time to the first analgesic request, postoperative analgesic doses, patient satisfaction, and complications were compared. RESULTS: Fifty-four patients received a paravertebral block alone (PECS 0), and 46 received a paravertebral block combined with blocks targeting the pectoral musculature (PECS 1). The highest intraoperative effect-site concentration of propofol was significantly lower in the PECS 1 group than in the PECS 0 group [2.3 (1.5, 2.8) vs 2.5 (1.5, 4) µg/mL, p = 0.0014]. The intraoperative rescue analgesic dose was significantly lower in the PECS 1 group [0 (0, 25) vs 0 (0, 75) mg of ketamine, p = 0.0384]. Furthermore, the PECS 1 group had a significantly longer time to the first analgesic request [636.5 (15, 720) vs 182.5 (14, 720) min, p = 0.0001]. After further adjustment for age, body mass index, American Society of Anesthesiologists Physical Status classification, chronic pain history, incidence of a superficial cervical plexus block placement, and operation duration, blocks targeting the pectoral musculature were determined to be the only significant factor (hazard ratio, 0.36; 95% confidence interval, 0.23-0.58; p < 0.0001). Very few patients used potent analgesics including morphine and ketorolac; the cumulative use of morphine or ketorolac was similar in the study groups. However, the incidence of all analgesic use, namely morphine, ketorolac, acetaminophen, and celecoxib, was significantly lower in the PECS 1 group [3.5 (0, 6) vs 5 (0, 12), p < 0.0001]. CONCLUSIONS: Compared with the placement of a paravertebral block alone, combining blocks targeting the pectoral musculature with a paravertebral block for modified radical mastectomy reduced the sedative and analgesic requirements during operation and provided more effective postoperative analgesia.

Feasibility of combined paravertebral block and subcostal transversus abdominis plane block in postoperative pain control after minimally invasive esophagectomy.

OBJECTIVES: Subcostal transversus abdominis plane (TAP) block and paravertebral block (PVB) offer postoperative analgesia for laparoscopic and thoracoscopic surgery, respectively. We investigated the early postoperative analgesic effects of PVB in combination with subcostal TAP block in patients undergoing minimally invasive esophagectomy (MIE) for esophageal cancer. METHODS: Seventeen patients undergoing MIE without nerve block for postoperative analgesia and 16 patients undergoing MIE with PVB and subcostal TAP block for postoperative analgesia were enrolled for the study. The surgeon performed PVB with bupivacaine at T4, T6, and T8 levels under video-assisted thoracoscopy at the end of the thoracoscopic stage. The anesthesiologist responsible for the anesthesia performed ultrasound-guided bilateral subcostal TAP with bupivacaine at the end of the surgery. Postoperative morphine consumption, pain severity, vital capacity, intensive care unit (ICU) stay, and complication rate were compared between groups. RESULTS: The group receiving nerve blocks consumed less morphine on postoperative Day 0 (p = 0.016), experienced lower levels of pain at postoperative 0 hour (p = 0.005) and 2 hours (p = 0.049), and had a shorter ICU stay (p = 0.02). No between-group differences in postoperative vital capacity and respiratory complications were observed. CONCLUSION: PVB in combination with subcostal TAP block could reduce morphine consumption and pain severity in the early postoperative period but did not offer other clinical benefits in MIE.

The effect on improvement of recovery and pain scores of paravertebral block immediately before breast surgery.

OBJECTIVES: Paravertebral block (PVB) has the potential to reduce postoperative pain after breast surgery. The aim of the study was to investigate whether PVB performed immediately before surgery could affect the postoperative morbidities in terms of pain and emesis, and improve the quality of recovery (QoR) in patients after surgery for breast cancer. METHODS: Postoperative data were collected prospectively from two groups of patients undergoing unilateral breast surgery during the study period of 1 month. Forty consecutive patients received either solely general anesthesia (GA group, n=25) or GA plus ultrasound-guided PVB (GA+PVB group, n=15) for the surgery. Pain scores and areal distribution of pain were compared between the two groups 1 hour and 6 hours postoperatively and on the midmorning of postoperative Day 1 (POD1). The QoR scores were compared between the two groups 6 hours postoperatively and on the midmorning of POD1. Incidence of postoperative nausea and vomiting and doses of analgesics and narcotics given were also compared. RESULTS: Pain scores at rest were significantly lower in the GA+PVB group at all designated time points [1 hour (p<0.0001), 6 hours (p<0.0001), and on midmorning of POD1 (p=0.041)]. Pain scores with movements was also significantly lower at all time points in the GA+PVB group (1 hour, p<0.0001; 6 hours, p<0.0001; midmorning of POD1, p=0.0012). Areal distribution of pain at rest and with movement was wider in the GA group 1 hour and 6 hours postoperately but was identical to that of GA+ PVB group on the mid-morning of POD1 [1 hour postoperatively at rest (p<0.0001), with movement (p<0.0001); 6 hours postoperatively at rest (p=0.0018), with movement (p=0.0048)]. The QoR scores were significantly higher in the GA+PVB group at 6 hours (p<0.0001) and on midmorning of POD1 (p=0.0079). The incidences of postoperative nausea and vomiting were significantly lower in the GA+PVB group (p=0.0004). Doses of postoperative analgesics and narcotics were significantly less in the GA+PVB group (p<0.0001 and p=0.001, respectively). Time to first request for analgesics was significantly longer in the GA+PVB group (p=0.0002). CONCLUSIONS: PVB given before surgery in combination with GA could provide better postoperative analgesia and better QoR than did GA alone in patients undergoing surgery for unilateral breast cancer.

A simple, innovative way to reduce rhinitis symptoms after sedation during endoscopy.

BACKGROUND: Supplmental oxygen is routinely given via nasal cannula (NC) to patients undergoing moderate sedation for endoscopy. Some patients complain of profuse rhinorrhea and/or sneezing after the procedure, which results in additional medical costs and patient dissatisfaction. OBJECTIVES: To determine the causal relationship between the route of oxygen delivery and troublesome nasal symptoms, and to seek possible solutions. METHODS: Patients (n=836) were randomly assigned to one of the three following groups: the NC group (n=294), the trimmed NC (TNC) group (n=268) and the nasal mask (NM) group (n=274). All received alfentanil 12.5 µg/kg and midazolam 0.06 mg/kg, and adjunct propofol for sedation. Supplemental oxygen at a flow rate of 4 L/min was used in the NC and TNC groups, and 6 L/min in the NM group. The incidence of nasal symptoms and hypoxia were assessed. RESULTS: The incidence of rhinitis symptoms was significantly higher in the NC group (7.1%) than in the TNC (0.4%) and NM (0%) groups (P<0.001). The incidence of hypoxia was lower in the NC group (3.1%) (P=0.040). All hypoxia events were transient (ie, less than 30 s in duration). On spirometry, the mean value of the lowest saturation of peripheral oxygen was found to be significantly lower in the NM group (96.8%) than in the NC group (97.7%) (P=0.004). CONCLUSIONS: Trimming the NC or using NMs reduced the incidence of rhinitis symptoms; however, the incidence of hypoxia was higher. Further investigation regarding the efficiency of oxygen supplementation is warranted in the design of novel oxygen delivery devices.