Changes in corrected carotid flow time induced by recruitment maneuver predict fluid responsiveness in patients undergoing general anesthesia

Non-invasive methods to assess patients' fluid responsiveness during lung-protective ventilation are needed. We hypothesized changes in the corrected carotid flow time induced by the recruitment maneuver predict fluid responsiveness under general anesthesia. Thirty patients undergoing general anesthesia in the supine position were prospectively enrolled. The study protocol was conducted when the patient was hemodynamically stable during surgery. Flow time was measured on Doppler images of the common carotid artery. Carotid flow time, heart rate, stroke volume, stroke volume variation, and pulse pressure variation were recorded before and after a recruitment maneuver at a continuous airway pressure of 30 cmH₂O for 30 s, and before and after volume expansion with 250 mL for 10 min. Patients were defined as fluid responders if the increase in stroke volume was > 10% after volume expansion. Twenty patients (67%) were fluid responders. All Doppler images for carotid flow time were obtained within 30 s. Changes in the corrected flow time accurately predicted fluid responsiveness (area under the curve: 0.82, 95% confidence interval [CI] 0.64-0.94, p = 0.002). The optimal threshold for changes in the corrected flow time was - 11.7% with a sensitivity of 95.0% (95% CI 75.1-99.9%) and a specificity of 80.0% (95% CI 44.4-97.5%). The gray-zone of changes in the corrected flow time was from - 25.1 to - 12.2% and included 12 patients (40%). Changes in the corrected carotid flow time were a useful, technically easy-to-perform, and non-invasive method to predict fluid responsiveness without a need for hemodynamic monitoring or arterial cannulation.

Respiratory variation in peripheral arterial blood flow peak velocity to predict fluid responsiveness in mechanically ventilated patients: a systematic review and meta-analysis

BACKGROUND

Fluid overloading is detrimental to organ function and results in a poor prognosis. It is necessary to evaluate fluid responsiveness before fluid loading. We performed a systematic meta-analysis to evaluate the diagnostic value of the respiratory variation in peripheral arterial blood flow peak velocity (△Vpeak PA) in predicting fluid responsiveness in mechanically ventilated patients.

METHODS

PubMed, Embase and The Cochrane Library databases were searched for studies that used △Vpeak PA to predict fluid responsiveness in mechanically ventilated patients. We calculated the pooled values of sensitivity, specificity and the area of the summary receiver operating characteristic curve by Meta-Disc 14.0 software.

RESULTS

Nine studies with a total of 402 patients were included. Two low quality studies were deleted in further analysis. Moreover, because of different locations of peripheral artery, the rest included studies were divided into brachial site group and carotid site group for meta-analysis individually. The pooled sensitivity, specificity and area under curve were 0.85 (95% confidence interval (CI) 0.77-0.92), 0.86 (95% CI 0.77-0.92) and 0.9268 in carotid site group. The pooled sensitivity, specificity and area under curve were 0.72 (95% CI 0.60-0.81), 0.85 (95% CI 0.74-0.93) and 0.8587 in brachial site group.

CONCLUSIONS

△Vpeak of carotid and brachial artery had a diagnostic value in predicting fluid responsiveness respectively. Moreover, △Vpeak of carotid artery had more value than brachial artery in predicting fluid responsiveness. However, there was some clinical heterogeneity; therefore, further studies are needed to confirm diagnostic accuracy.

Early fluid loading for septic patients: Any safety limit needed?

Early adequate fluid loading was the corner stone of hemodynamic optimization for sepsis and septic shock. Meanwhile, recent recommended protocol for fluid resuscitation was increasingly debated on hemodynamic stability vs risk of overloading. In recent publications, it was found that a priority was often given to hemodynamic stability rather than organ function alternation in the early fluid resuscitation of sepsis. However, no safety limits were used at all in most of these reports. In this article, the rationality and safety of early aggressive fluid loading for septic patients were discussed. It was concluded that early aggressive fluid loading improved hemodynamics transitorily, but was probably traded off with a follow-up organ function impairment, such as worsening oxygenation by reduction of lung aeration, in a part of septic patients at least. Thus, a safeguard is needed against unnecessary excessive fluids in early aggressive fluid loading for septic patients.

Recognition and treatment of severe sepsis in the emergency department: retrospective study in two French teaching hospitals

BACKGROUND

Sepsis management in the Emergency Department remains a daily challenge. The Surviving Sepsis Campaign (SSC) has released three-hour bundle. The implementation of these bundles in European Emergency Departments remains poorly described. The main objective was to assess the compliance with the Severe Sepsis Campaign 3-h bundle (blood culture, lactate dosage, first dose of antibiotics and 30 ml/kg fluid challenge). Secondary objectives were the analysis of the delay of severe sepsis recognition and description of the population.

METHODS

In accordance with STROBE statement, we performed a retrospective study in two French University Hospital Emergency Departments from February to August 2015. Patients admitted during the study period were screened using the electronic files of the hospital databases. Patient's files were reviewed and included in the study if they met severe sepsis criteria. Demographics, comorbities, treatments were recorded. Delays from admission to severe sepsis diagnosis, fluid loading onset and antibiotics administration were calculated.

RESULTS

One hundred thirty patients were included (76 men, mean age 71 ± 14 years). Blood culture, lactate dosage, antibiotics and 30 ml/kg fluid loading were performed within 3 hours in % [95% confidence interval] 100% [96-100%], 62% [54-70%], 49% [41-58%] and 19% [13-27%], respectively. 25 patients out of 130 (19% [13-27%]) fulfilled each criteria of the 3-h bundle. The mean fluid loading volume was 18 ± 11 ml/kg. Mean delay between presentation and severe sepsis diagnosis was 200 ± 263 min, from diagnosis to fluid challenge and first antibiotic dose, 10 ± 27 min and 20 ± 55 min, respectively.

CONCLUSION

Compliance with SSC 3-h bundle and delay between admission and sepsis recognition have to be improved. If confirmed by other studies, an improvement program might be deployed.

Assessment of macro- and micro-oxygenation parameters during fractional fluid infusion: A pilot study

PURPOSE

The main goal of this study was to assess whether maximal fluid infusion improves both oxygen delivery (DO₂) and micro-circulatory parameters during hemodilution. The secondary objective was to assess the ability of baseline micro-circulatory parameters to predict oxygen consumption (VO₂) response following fluid infusion.

MATERIALS AND METHODS

In a postoperative cardiac ICU, patients received repeated fluid infusion until stroke volume (SV) was maximized. Before and after each fluid expansion, macro- (DO₂, VO₂) and micro-circulatory oxygenation parameters were recorded [central venous oxygen saturation (ScVO₂), blood lactate, difference in veno-arterial carbon dioxide tension (P(v-a)CO₂), somatic and cerebral oxygen saturation (rSO₂)]. Patients were classified as VO₂-Responders or VO₂-Non-Responders according to an increase in VO₂ above or below 15%, respectively.

RESULTS

After maximal fluid infusion, all patients showed improved macro- and micro-circulatory oxygenation parameters, but VO₂-Responders had lower values (especially for ScVO₂ and cerebral rSO₂). Only baseline ScVO₂ and cerebral rSO₂ were useful to predict the VO₂ response to maximal fluid infusion (ROC_AUC 0.80 (95% CI: 0.54-0.95, P=0.012) and 0.83 (95% CI: 0.57-0.96, P=0.001).

CONCLUSIONS

Maximal fluid infusion improves macro- and micro-circulatory oxygenation parameters. For VO₂-Responders, only ScVO₂ and cerebral rSO₂ could serve as markers of tissue hypoxia.

Hemodynamics of mesenteric traction syndrome measured by FloTrac sensor

BACKGROUND

Mesenteric traction syndrome (MTS) develops in the early phase of laparotomy, which is triggered by pulling of the mesentery. We attempted to analyze the circulatory dynamics of MTS by using the FloTrac sensor.

METHODS

Prospective randomized control study, the MTS trial, was conducted with or without prophylactic administration of flurbiprofen axetil in order to control MTS development in 57 elective open colorectal surgeries. None of the Flurbipurofen group patients (n = 23) develop MTS and were allocated to the non-MTS group. Among the non-flurbiprofen group, 28 patients (82%) developed MTS and were categorized into the MTS group. For these patients, in addition to blood pressure, stroke volume variation (SVV) and systemic vascular resistance index (SVRI) were measured by FloTrac sensor.

RESULTS

The lowest blood pressure was noted within 30 minutes from the beginning of the intra-abdominal examination; in the non-MTS group, the mean blood pressure decreased by 16.7%, and in the MTS group, it decreased by 34.2% (P < .01). SVV of the 28 MTS patients was as follows: <9% in 10 patients (35.7%), >9% and <13% in 8 patients (28.6%), and >13% in 10 patients (35.7%). SVRI rose in the non-MTS group by 5.1%, whereas it fell in the MTS group by 15.1% (P < .01), indicating the close relationship between MTS and SVRI.

CONCLUSIONS

The SVV results indicate that fluid loading is not that optimal treatment against hypotension of MTS and that it is also important to consider the use of a vasoconstrictor. FloTrac is therefore useful for making an appropriate decision on the treatment strategy for MTS.

Tissue perfusion and oxygenation to monitor fluid responsiveness in critically ill, septic patients after initial resuscitation: a prospective observational study

Fluid therapy after initial resuscitation in critically ill, septic patients may lead to harmful overloading and should therefore be guided by indicators of an increase in stroke volume (SV), i.e. fluid responsiveness. Our objective was to investigate whether tissue perfusion and oxygenation are able to monitor fluid responsiveness, even after initial resuscitation. Thirty-five critically ill, septic patients underwent infusion of 250 mL of colloids, after initial fluid resuscitation. Prior to and after fluid infusion, SV, cardiac output sublingual microcirculatory perfusion (SDF: sidestream dark field imaging) and skin perfusion and oxygenation (laser Doppler flowmetry and reflectance spectroscopy) were measured. Fluid responsiveness was defined by a ≥5 or 10 % increase in SV upon fluids. In responders to fluids, SDF-derived microcirculatory and skin perfusion and oxygenation increased, but only the increase in cardiac output, mean arterial and pulse pressure, microvascular flow index and relative Hb concentration and oxygen saturation were able to monitor a SV increase. Our proof of principle study demonstrates that non-invasively assessed tissue perfusion and oxygenation is not inferior to invasive hemodynamic measurements in monitoring fluid responsiveness. However skin reflectance spectroscopy may be more helpful than sublingual SDF.