Microplastics are ubiquitously found in freshwater and marine environments worldwide. In particular, wastewater treatment plants (WWTPs) or sewage treatment plants (STPs) have been recognized as a main source of microplastics in the receiving freshwater. However, only a few studies have been conducted to examine the impact of these facilities on receiving waters. In this study, we investigated the distribution of microplastics in surface water, fish, and sediment near a sewage treatment plant (STP) in the Tanchon stream, one of the main tributaries flowing into the Han River, Korea. The concentration of microplastics in water varied spatially and temporarily, ranging between 5.3 and 87.3 particles/m3 (31.4 ± 28.5 particles/m3). In fish, the concentration in upstream and downstream sites was 7.3 ± 7.3 and 12.4 ± 17.9 particles/fish, respectively. Spatially, the downstream site was the most polluted with microplastics in water and fish. The concentration of microplastics was positively correlated with fish body length and weight. In sediment, microplastic concentration in upstream and downstream sites was 493.1 ± 136.0 and 380.0 ± 144.2 particles/kg, respectively. The contribution of upstream to the microplastic load in downstream was 15.8% in dry season (April), which was higher than that of STP effluent and Yangjaechon creek. Meanwhile, the highest load was observed in STP effluent (5.1%) in rainy season (August). Microplastics were more abundant in water in the rainy season (37.4 ± 37.0 particles/m3) than in the dry season (28.2 ± 22.2 particles/m3). Polyethylene (49%) and polypropylene (18%) were the most abundant polymer types in water, fish, and sediment. Regarding shape of microplastics, fragments were dominant (95%) over fiber and film in water, fish, and sediment.

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Anesthesia for percutaneous transluminal angioplasty (PTA) involves a high-risk population having a broad spectrum of pain character and intensity. This study delved the anesthetic efficacy of dexmedetomidine versus midazolam, when used with remifentanil. Seventy patients scheduled for femoropopliteal PTA were randomized into two groups receiving either intermittent midazolam boluses (0.03–0.05 mg/kg) (MR group) or dexmedetomidine 0.2–0.7 μg/kg/h after a loading dose of 1.0 μg/kg for 10 min (DR group), both with remifentanil. The primary endpoint was the patients’ satisfaction (1–5, 5; extremely satisfied). Secondary endpoints included postprocedural pain scores (0–10, 10; worst imaginable pain) and adverse events. The satisfaction level of patients was significantly greater in the DR group compared with the MR group (4.0 [3.0, 5.0] versus 4.0 [2.0, 5.0] p = 0.021). The number of patients having a postprocedural pain score of at least 3 was significantly greater in the MR group compared with the DR group (10 [29%] versus 2 [6%], p = 0.013). The number of patients with hypotensive episodes was higher in the DR group (5 [14.7%] versus 0, p = 0.025), which could all be restored with ephedrine. The use of dexmedetomidine in conjunction with remifentanil may be a safe option that provides excellent patient satisfaction while potentially attenuating postprocedural pain.

Dexmedetomidine is used for sedation during spinal anesthesia. The sympatholytic effect of dexmedetomidine may exacerbate hypotension and bradycardia with spinal anesthesia. This study investigated the effects of prophylactic intramuscular injection of ephedrine in preventing hypotension and bradycardia occurring through combined use of spinal anesthesia and dexmedetomidine. One hundred sixteen patients scheduled for lower extremity orthopedic surgery were randomized into two groups receiving either ephedrine 20 mg intramuscularly or equivalent amount of 0.9% NaCl, both with dexmedetomidine and spinal anesthesia. The primary endpoint was the incidence of hemodynamic perturbations (hypotension or bradycardia event). The secondary endpoint was a rescue doses of ephedrine and atropine. The incidence of hemodynamic perturbations was significantly lower in the ephedrine group compared with to the saline group (26.3% versus 55.9%, p = 0.001). The rescue doses of atropine (0.09 ± 0.21 versus 0.28 ± 0.41, p = 0.001) and ephedrine (1.04 ± 2.89 versus 2.03 ± 3.25, p = 0.007) were also significantly lower in the ephedrine group. There was no differences in number of patients with hypertensive (7.0% versus 11.9%, p = 0.375) or tachycardia (1.8% versus 3.4% p = 0.581) episodes. The use of ephedrine intramuscular injections may be a safe and efficacious option in preventing hemodynamic perturbations in patients who received spinal anesthesia and sedation using dexmedetomidine.

Thoracic surgery using CO2 insufflation maintains closed-chest one-lung ventilation (OLV) that may provide the necessary heart–lung interaction for the dynamic indices to predict fluid responsiveness. We studied whether pulse pressure variation (PPV) and stroke volume variation (SVV) can predict fluid responsiveness during thoracoscopic surgery. Forty patients were enrolled in the study. OLV was performed with a tidal volume of 6 mL/kg at a positive end-expiratory pressure of 5 cm H2O, while CO2 was insufflated to the contralateral side at 8 mm Hg. Patients whose stroke volume index (SVI) increased ≥15% after fluid challenge (7 mL/kg) were defined as fluid responders. The predictive ability of PPV and SVV on fluid responsiveness was investigated using the area under the receiver-operator characteristic curve (AUROC), which was also assessed according to the right or left lateral decubitus position considering the intrathoracic location of the right-sided superior vena cava. AUROCs of PPV and SVV for predicting fluid responsiveness were 0.65 (95% confidence interval 0.47–0.83, p = 0.113) and 0.64 (95% confidence interval 0.45–0.82, p = 0.147), respectively. The AUROCs of indices did not exhibit any statistical significance according to position. Dynamic indices of preload cannot predict fluid responsiveness during one-lung ventilation with CO2 gas insufflation.