Computed Tomography Assessment of Tidal Lung Overinflation in Domestic Cats Undergoing Pressure-Controlled Mechanical Ventilation During General Anesthesia.

Objective: This study aimed to evaluate lung overinflation at different airway inspiratory pressure levels using computed tomography in cats undergoing general anesthesia. Study Design: Prospective laboratory study. Animals: A group of 17 healthy male cats, aged 1.9-4.5 years and weighing 3.5 ± 0.5 kg. Methods: Seventeen adult male cats were ventilated in pressure-controlled mode with airway pressure stepwise increased from 5 to 15 cmH2O in 2 cmH2O steps every 5 min and then stepwise decreased. The respiratory rate was set at 15 movements per min and end-expiratory pressure at zero (ZEEP). After 5 min in each inspiratory pressure step, a 4 s inspiratory pause was performed to obtain a thoracic juxta-diaphragmatic single slice helical CT image and to collect respiratory mechanics data and an arterial blood sample. Lung parenchyma aeration was defined as overinflated, normally-aerated, poorly-aerated, and non-aerated according to the CT attenuation number (-1,000 to -900 HU, -900 to -500 HU, -500 to -100 HU, and -100 to +100 HU, respectively). Result: At 5 cmH2O airway pressure, tidal volume was 6.7± 2.2 ml kg-1, 2.1% (0.3-6.3%) of the pulmonary parenchyma was overinflated and 84.9% (77.6%-87.6%) was normally inflated. Increases in airway pressure were associated with progressive distention of the lung parenchyma. At 15 cmH2O airway pressure, tidal volume increased to 31.5± 9.9 ml kg-1 (p < 0.001), overinflated pulmonary parenchyma increased to 28.4% (21.2-30.6%) (p < 0.001), while normally inflated parenchyma decreased 57.9% (53.4-62.8%) (p < 0.001). Tidal volume and overinflated lung fraction returned to baseline when airway pressure was decreased. A progressive decrease was observed in arterial carbon dioxide partial pressure (PaCO2) and end-tidal carbon dioxide (ETCO2) when the airway pressures were increased above 9 cmH2O (p < 0.001). The increase in airway pressure promoted an elevation in pH (p < 0.001). Conclusions and Clinical Relevance: Ventilation with 5 and 7 cmH2O of airway pressure prevents overinflation in healthy cats with highly compliant chest walls, despite presenting acidemia by respiratory acidosis. This fact can be controlled by increasing or decreasing respiratory rate and inspiratory time.

Effect of Slower vs Faster Intravenous Fluid Bolus Rates on Mortality in Critically Ill Patients: The BaSICS Randomized Clinical Trial.

Importance: Slower intravenous fluid infusion rates could reduce the formation of tissue edema and organ dysfunction in critically ill patients; however, there are no data to support different infusion rates during fluid challenges for important outcomes such as mortality. Objective: To determine the effect of a slower infusion rate vs control infusion rate on 90-day survival in patients in the intensive care unit (ICU). Design, Setting, and Participants: Unblinded randomized factorial clinical trial in 75 ICUs in Brazil, involving 11 052 patients requiring at least 1 fluid challenge and with 1 risk factor for worse outcomes were randomized from May 29, 2017, to March 2, 2020. Follow-up was concluded on October 29, 2020. Patients were randomized to 2 different infusion rates (reported in this article) and 2 different fluid types (balanced fluids or saline, reported separately). Interventions: Patients were randomized to receive fluid challenges at 2 different infusion rates; 5538 to the slower rate (333 mL/h) and 5514 to the control group (999 mL/h). Patients were also randomized to receive balanced solution or 0.9% saline using a factorial design. Main Outcomes and Measures: The primary end point was 90-day survival. Results: Of all randomized patients, 10 520 (95.2%) were analyzed (mean age, 61.1 years [SD, 17.0 years]; 44.2% were women) after excluding duplicates and consent withdrawals. Patients assigned to the slower rate received a mean of 1162 mL on the first day vs 1252 mL for the control group. By day 90, 1406 of 5276 patients (26.6%) in the slower rate group had died vs 1414 of 5244 (27.0%) in the control group (adjusted hazard ratio, 1.03; 95% CI, 0.96-1.11; P = .46). There was no significant interaction between fluid type and infusion rate (P = .98). Conclusions and Relevance: Among patients in the intensive care unit requiring fluid challenges, infusing at a slower rate compared with a faster rate did not reduce 90-day mortality. These findings do not support the use of a slower infusion rate. Trial Registration: ClinicalTrials.gov Identifier: NCT02875873.

Renal and cardiovascular repercussions in preeclampsia and their impact on fluid management: a literature review.

Preeclampsia is a multifactorial condition associated with significant morbidity and mortality. Fluid therapy in these patients is challenging since volume expansion may precipitate pulmonary edema, and fluid restriction may worsen renal function. Furthermore, cardiac impairment may introduce an additional component to the hemodynamic management. This article reviews the repercussions of preeclampsia on renal and cardiovascular systems and the development of pulmonary edema, as well as to discuss fluid management, focusing on the mitigation of adverse outcomes and monitoring alternatives. The literature review was carried out using PubMed, Embase, and Google Scholar databases from May 2019 to March 2020. Papers addressing the subjects of interest were included regardless of the publication language. There is a current trend towards restricting the administration of fluids in women with non-complicated preeclampsia. However, patients with preeclampsia may experience hemorrhagic shock, requiring volume resuscitation. In this case, hemodynamic monitoring is recommended to guide fluid therapy while avoiding complications.

Restrictive versus Liberal Fluid Therapy for Post-Cesarean Acute Kidney Injury in Severe Preeclampsia: a Pilot Randomized Clinical Trial.

OBJECTIVES: The aim of this study was to determine whether a restrictive compared to a liberal fluid therapy will increase postoperative acute kidney injury (AKI) in patients with severe preeclampsia. METHODS: A total of 46 patients (mean age, 32 years; standard deviation, 6.8 years) with severe preeclampsia were randomized to liberal (1500 ml of lactated Ringer's, n=23) or restrictive (250 ml of lactated Ringer's, n=23) intravenous fluid regimen during cesarean section. The primary outcome was the development of a postoperative renal dysfunction defined by AKI Network stage ≥1. Serum cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated at postoperative days 1 and 2. ClinicalTrials.gov: NCT02214186. RESULTS: The rate of postoperative AKI was 43.5% in the liberal fluid group and 43.5% in the restrictive fluid group (p=1.0). Intraoperative urine output was higher in the liberal (116 ml/h, IQR 69-191) than in the restrictive fluid group (80 ml/h, IQR 37-110, p<0.05). In both groups, serum cystatin C did not change from postoperative day 1 compared to the preoperative period and significantly decreased on postoperative day 2 compared to postoperative day 1 (p<0.05). In the restrictive fluid group, NGAL levels increased on postoperative day 1 compared to the preoperative period (p<0.05) and decreased on postoperative day 2 compared to postoperative day 1 (p<0.05). CONCLUSION: Among patients with severe preeclampsia, a restrictive fluid regimen during cesarean section was not associated with increased postoperative AKI.

Impact of perioperative hemodynamic optimization therapies in surgical patients: economic study and meta-analysis.

BACKGROUND: Several studies suggest that hemodynamic optimization therapies can reduce complications, the length of hospital stay and costs. However, Brazilian data are scarce. Therefore, the objective of this analysis was to evaluate whether the improvement demonstrated by hemodynamic optimization therapy in surgical patients could result in lower costs from the perspective of the Brazilian public unified health system. METHODS: A meta-analysis was performed comparing surgical patients who underwent hemodynamic optimization therapy (intervention) with patients who underwent standard therapy (control) in terms of complications and hospital costs. The cost-effectiveness analysis evaluated the clinical and financial benefits of hemodynamic optimization protocols for surgical patients. The analysis considered the clinical outcomes of randomized studies published in the last 20 years that involved surgeries and hemodynamic optimization therapy. Indirect costs (equipment depreciation, estate and management activities) were not included in the analysis. RESULTS: A total of 21 clinical trials with a total of 4872 surgical patients were selected. Comparison of the intervention and control groups showed lower rates of infectious (RR = 0.66; 95% CI = 0.58-0.74), renal (RR = 0.68; 95% CI = 0.54-0.87), and cardiovascular (RR = 0.87; 95% CI = 0.76-0.99) complications and a nonstatistically significant lower rate of respiratory complications (RR = 0.82; 95% CI = 0.67-1.02). There was no difference in mortality (RR = 1.02; 95% CI = 0.80-1.3) between groups. In the analysis of total costs, the intervention group showed a cost reduction of R$396,024.83-BRL ($90,161.38-USD) for every 1000 patients treated compared to the control group. The patients in the intervention group showed greater effectiveness, with 1.0 fewer days in the intensive care unit and hospital. In addition, there were 333 fewer patients with complications, with a consequent reduction of R$1,630,341.47-BRL ($371,173.27-USD) for every 1000 patients treated. CONCLUSIONS: Hemodynamic optimization therapy is cost-effective and would increase the efficiency of and decrease the burden of the Brazilian public health system.

Restrictive versus liberal fluid therapy for post-cesarean acute kidney injury in severe preeclampsia: a pilot randomized clinical trial

OBJECTIVES: The aim of this study was to determine whether a restrictive compared to a liberal fluid therapy will increase postoperative acute kidney injury (AKI) in patients with severe preeclampsia. METHODS: A total of 46 patients (mean age, 32 years; standard deviation, 6.8 years) with severe preeclampsia were randomized to liberal (1500 ml of lactated Ringer's, n=23) or restrictive (250 ml of lactated Ringer's, n=23) intravenous fluid regimen during cesarean section. The primary outcome was the development of a postoperative renal dysfunction defined by AKI Network stage ≥1. Serum cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated at postoperative days 1 and 2. ClinicalTrials.gov: NCT02214186. RESULTS: The rate of postoperative AKI was 43.5% in the liberal fluid group and 43.5% in the restrictive fluid group (p=1.0). Intraoperative urine output was higher in the liberal (116 ml/h, IQR 69-191) than in the restrictive fluid group (80 ml/h, IQR 37-110, p<0.05). In both groups, serum cystatin C did not change from postoperative day 1 compared to the preoperative period and significantly decreased on postoperative day 2 compared to postoperative day 1 (p<0.05). In the restrictive fluid group, NGAL levels increased on postoperative day 1 compared to the preoperative period (p<0.05) and decreased on postoperative day 2 compared to postoperative day 1 (p<0.05). CONCLUSION: Among patients with severe preeclampsia, a restrictive fluid regimen during cesarean section was not associated with increased postoperative AKI.