[Evaluation of fluid responsiveness in patients with septic shock by critical ultrasound with small dose fluid challenge].

OBJECTIVE: To explore the value of critical ultrasound in evaluating the fluid responsiveness of small dose volume challenge in patients with septic shock. METHODS: Thirty-six patients with septic shock admitted to the Third People's Hospital of Datong from January 2021 to December 2021 were enrolled, and the patients were randomly divided into control group and observation group, with 18 patients in each group. The control group was treated with traditional fluid challenge (500 mL of crystalloid injected within 30 minutes); the observation group received a small dose fluid challenge (100 mL of crystalloid injected within 1 minute). The hemodynamic indexes [central venous pressure (CVP), invasive mean arterial pressure (MAP), velocity-time integra (VTI)] and bilateral lung ultrasound scores were measured by critical ultrasound in both groups. The outcome related indicators of patients in the two groups were observed. The correlation between the above indexes and the fluid challenge was evaluated. RESULTS: Compared with the control group, the heart rate (HR) and CVP of patients in the observation group after the challenge were significantly lower than those in the control group [HR (times/min): 99.74±3.22 vs. 107.65±3.14, CVP (mmHg, 1 mmHg ≈ 0.133 kPa): 7.55±0.22 vs. 10.26±0.52, both P < 0.05], invasive MAP and VTI were significantly higher than those in the control group [invasive MAP (mmHg): 77.36±2.14 vs. 69.81±2.56, VTI (cm/s): 68.85±1.26 vs. 44.71±1.28, both P < 0.05]. The ultrasonic score of the observation group was significantly better than those of the control group (all P < 0.05). In terms of outcome, the length of intensive care unit (ICU) stay, mechanical ventilation time and the time for urine volume more than 0.5 mL×kg-1×h-1 of the observation group were significantly shorter than those in the control group [the length of ICU stay (hours): 138.26±1.25 vs. 205.73±1.26, mechanical ventilation time (hours): 36.80±0.25 vs. 47.65±0.36, time to reach urine volume more than 0.5 mL×kg-1×h-1 (hours): 27.38±1.25 vs. 38.61±1.30, all P < 0.05], The dosage of norepinephrine was significantly decreased in the observation group compared with the control group (mg: 45.26±1.85 vs. 53.73±1.92, P < 0.05), and the amount of resuscitation crystalloid was significantly reduced compared with the control group (mL: 1 532.62±12.38 vs. 1 755.52 ± 12.30, P < 0.05). Correlation analysis showed that the volume of crystalloid was highly consistent with M-BLUE pulmonary ultrasound (zone 2, 4 and 5), mechanical ventilation time, norepinephrine dose, time to reach the standard of urine volume and ΔVTI (all P < 0.05). CONCLUSIONS: Small dose fluid challenge evaluated by critical ultrasound in septic shock patients has a high value for fluid responsiveness, which can better reduce the risk of obvious tissue edema caused by fluid overload, organ damage and even life-threatening, make fluid challenge more reasonable and appropriate, thereby improving the success of treatment.

High-flow nasal cannula versus conventional oxygen therapy in acute COPD exacerbation with mild hypercapnia: a multicenter randomized controlled trial.

BACKGROUND: High-flow nasal cannula (HFNC) can improve ventilatory function in patients with acute COPD exacerbation. However, its effect on clinical outcomes remains uncertain. METHODS: This randomized controlled trial was conducted from July 2017 to December 2020 in 16 tertiary hospitals in China. Patients with acute COPD exacerbation with mild hypercapnia (pH ≥ 7.35 and arterial partial pressure of carbon dioxide > 45 mmHg) were randomly assigned to either HFNC or conventional oxygen therapy. The primary outcome was the proportion of patients who met the criteria for intubation during hospitalization. Secondary outcomes included treatment failure (intolerance and need for non-invasive or invasive ventilation), length of hospital stay, hospital cost, mortality, and readmission at day 90. RESULTS: Among 337 randomized patients (median age, 70.0 years; 280 men [83.1%]; median pH 7.399; arterial partial pressure of carbon dioxide 51 mmHg), 330 completed the trial. 4/158 patients on HFNC and 1/172 patient on conventional oxygen therapy met the criteria for intubation (P = 0.198). Patients progressed to NPPV in both groups were comparable (15 [9.5%] in the HFNC group vs. 22 [12.8%] in the conventional oxygen therapy group; P = 0.343). Compared with conventional oxygen therapy, HFNC yielded a significantly longer median length of hospital stay (9.0 [interquartile range, 7.0-13.0] vs. 8.0 [interquartile range, 7.0-11.0] days) and a higher median hospital cost (approximately $2298 [interquartile range, $1613-$3782] vs. $2005 [interquartile range, $1439-$2968]). There were no significant differences in other secondary outcomes between groups. CONCLUSIONS: In this multi-center randomized controlled study, HFNC compared to conventional oxygen therapy did not reduce need for intubation among acute COPD exacerbation patients with mild hypercapnia. The future studies should focus on patients with acute COPD exacerbation with respiratory acidosis (pH < 7.35). However, because the primary outcome rate was well below expected, the study was underpowered to show a meaningful difference between the two treatment groups. TRIAL REGISTRATION: NCT03003559 . Registered on December 28, 2016.