Easy method to determine fluid responsiveness in septic shock patients: end-tidal CO2 - a prospective observational study.

BACKGROUND: In critically ill patients, especially those with septic shock, fluid management can be a challenging aspect of clinical care. One of the primary steps in treating patients with hemodynamic instability is optimizing intravascular volume. The Passive Leg Raising (PLR) maneuver is a reliable test for assessing fluid responsiveness, as demonstrated by numerous studies and meta-analyses. However, its use requires the measurement of cardiac output, which is often complex and may necessitate clinician experience and specialized equipment. End-Tidal Carbon Dioxide (ETCO2) measurement is relatively easy and is generally stable under steady metabolic conditions. It depends on the body's CO2 production, diffusion of CO2 from the lungs into the bloodstream, and cardiac output. If the other two parameters (metabolic conditions and minute ventilation) are constant, ETCO2 can provide information about cardiac output. The aim of the present study is to investigate the sensitivity of ETCO2 measurement in demonstrating fluid responsiveness. METHODS: All patients diagnosed with septic shock and meeting the inclusion criteria were subjected to a passive leg raising test, and cardiac outputs were measured by echocardiography. An increase in cardiac output of 15% or more was considered indicative of the fluid responder group, while patients with an increase below 15% or no increase were classified as the non-responder group. Patients' intensive care unit admission diagnoses, initial laboratory parameters, tidal volume, minute volume before and after the PLR maneuver, mean and systolic blood pressure, heart rate, Pulse Pressure Variation (PPV) values, and ETCO2 values were recorded. RESULTS: Before and after the ETCO2 test, there was no statistically significant difference between the two groups. However, the change in ETCO2 (ΔETCO2) was significantly higher in the responder group. In the non-responder group, ΔETCO2 was 2.57% (0.81), whereas it was 5.71% (2.83) in the responder group (p<0.001). Receiver Operating Characteristic (ROC) analysis was performed for ΔETCO2, baseline Stroke Volume Variation (SVV), ΔSVV, baseline Heart Rate (HR), ΔHR, baseline PPV, and ΔPPV to predict fluid responsiveness. ΔETCO2 predicted fluid responsiveness with a sensitivity of 85% and a specificity of 86% when it was 4% or higher. When ΔETCO2 was 5% or higher, it predicted fluid responsiveness with a specificity of 99.3% and a sensitivity of 75.5%, with an Area Under the Curve (AUC) of 0.89 (95% confidence interval, 0.828-0.961). CONCLUSION: This study demonstrates that in septic patients, ETCO2 during the PLR test can indicate fluid responsiveness with high sensitivity and specificity and can be used as an alternative to cardiac output measurement.

Risks of Polymyxin B Nephrotoxicity and Its Precursors in the Intensive Care Unit: A Retrospective Cohort Study.

BACKGROUND AND AIM: Polymyxin group antibiotics constitute a part of our limited arsenal in the treatment of multidrug-resistant gram-negative bacteria. However, their use is limited especially due to nephrotoxicity and other side effects. In this study, we primarily aimed to determine the effect of polymyxin B on the rate of nephrotoxicity in critically ill patients, and secondly to identify the factors that facilitate nephrotoxicity caused by polymyxin B. MATERIALS AND METHODS: The study was designed as a retrospective cohort study and conducted by scanning patients aged 18 years or older who had been admitted to our intensive care unit (ICU) in 2022 and treated with polymyxin B for at least 72 hours. Patients without chronic renal failure and acute kidney injury (AKI) before starting polymyxin B therapy were included and AKI was examined after the use of polymyxin B. The patients were then divided into two groups, those with AKI and those without AKI. We tried to find factors that may facilitate AKI by comparing the two groups. RESULTS: Of the patients, 26 were female and 34 were male. In 21 of the patients (35%), renal damage of varying degrees developed; these patients belonged to the nephrotoxicity (NT) group, while the rest belonged to the non-nephrotoxicity (non-NT) group. We found that advanced age (p=0.008), low baseline GFR (p=0.01), baseline creatinine (p=0.006), BMI (p=0.011), concomitant diseases (p<0.001), and days of use of polymyxin B (p=0.006) were statistically different between the two groups. In multivariate analysis of univariate analysis, we found that duration of polymyxin B use, BMI, and advanced age were independent risk factors for AKI development. CONCLUSION: We found that 21 (35%) of 60 intensive care unit patients who had no previous history of kidney injury developed kidney injury after being treated with polymyxin B. We identified advanced age, high BMI, and duration of polymyxin B use as independent risk factors. Therefore, we recommend close monitoring of renal function and prompt intervention, particularly in patients with risk factors, during polymyxin B use.

Comparison of Optic Nerve Sheath Diameters Measured by Optic Ultrasonography Before and After Lumbar Puncture in Idiopathic Intracranial Hypertension Patients.

Introduction: Idiopathic intracranial hypertension (IIH) symptoms include headache, blurred vision, and papilledema which may lead to permanent vision loss unless diagnosed and treated. Definitive diagnosis of IIH usually requires the measurement of intracranial pressure (ICP) via lumbar puncture (LP) which is an invasive and unwanted technique for patients. In our study, optic nerve sheath diameters (ONSD) were measured before and after lumbar puncture in IIH patients and the relationship of these measurements with ICP changes was evaluated as well as the effect of decreasing cerebrospinal fluid (CSF) pressure after a lumbar puncture on ONSD. Thus, we want to investigate whether optic nerve ultrasonography (USG) is a useful tool instead of the invasive LP for the diagnosis of IIH. Methods: A total of 25 patients who applied to the neurology clinics of Ankara Numune Training and Research Hospital between May 2014 and December 2015 and were diagnosed with IIH were included in the study. The control group consisted of 22 individuals who applied with complaints other than headaches, visual impairment or tinnitus. Optic nerve sheath diameters were measured from both eyes before and after the LP. After pre-LP measurements were taken, opening and closing CSF pressure was measured. In the control group, ONSD was measured with optic USG. Results: Mean age of the IIH group and the control group was determined as 34.8±11.5 and 45.8±13.3 years, respectively. In the patient group, mean CSF opening pressure was 33.9±8.0 cm H2O and mean closing pressure was 18.1±4.7 cm H2O. Mean ONSD measured pre-LP was 7.1±1.0 mm in the right eye and 6.9±0.7 mm in the left eye, while mean post-LP ONSD was 6.7±0.9 mm in the right eye and 6.4±0.8 mm in the left eye. There was a statistically significant difference between ONSD values before and after the LP (p=0.006 for the right eye, p<0.001 for the left eye). In the control group, mean ONSD was 5.4±0.7 mm in the right eye and 5.5±0.6 mm in the left eye, and a statistically significant difference was found between ONSD values before and after the LP (p<0.001 for the right eye and left eye). A significant positive correlation was determined between left ONSD measurements before the LP and CSF opening pressure (r=0.501, p=0.011). Conclusions: In the present study, it was found that ONSD measurement by optic USG significantly displays increased ICP, and decreasing pressure via LP is rapidly reflecting ONSD measurement. Based on these findings, it is suggested that ONSD measurements by optic USG, a non-invasive method, can be used in the diagnosis and follow-up of IIH patients.