Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery.

To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH2O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH2O, in steps of 2 cmH2O to find the lung's closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH2O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO2), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 ± 1.7 cmH2O corresponding to a positive end-expiratory transpulmonary pressure (PL,ee) of 0.9 ± 1.1 cmH2O. ROC analysis showed that SpO2 was more accurate (AUC 0.92, IC95% 0.87-0.97) than Crs (AUC 0.76, IC95% 0.87-0.97) and EELVCO2 (AUC 0.73, IC95% 0.64-0.82) to detect the lung's closing pressure according to the change of PL,ee from positive to negative values. Compared to baseline ventilation with 8 cmH2O of PEEP, OLA increased EELVCO2 (1309 ± 517 vs. 2177 ± 679 mL) and decreased driving pressure (18.3 ± 2.2 vs. 10.1 ± 1.7 cmH2O), estimated shunt (17.7 ± 3.4 vs. 4.2 ± 1.4%), lung strain (0.39 ± 0.07 vs. 0.22 ± 0.06) and lung elastance (28.4 ± 5.8 vs. 15.3 ± 4.3 cmH2O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings.Clinical trial number NTC03694665.

Photoplethysmographic characterization of vascular tone mediated changes in arterial pressure: an observational study.

To determine whether a classification based on the contour of the photoplethysmography signal (PPGc) can detect changes in systolic arterial blood pressure (SAP) and vascular tone. Episodes of normotension (SAP 90-140 mmHg), hypertension (SAP > 140 mmHg) and hypotension (SAP < 90 mmHg) were analyzed in 15 cardiac surgery patients. SAP and two surrogates of the vascular tone, systemic vascular resistance (SVR) and vascular compliance (Cvasc = stroke volume/pulse pressure) were compared with PPGc. Changes in PPG amplitude (foot-to-peak distance) and dicrotic notch position were used to define 6 classes taking class III as a normal vascular tone with a notch placed between 20 and 50% of the PPG amplitude. Class I-to-II represented vasoconstriction with notch placed > 50% in a small PPG, while class IV-to-VI described vasodilation with a notch placed < 20% in a tall PPG wave. 190 datasets were analyzed including 61 episodes of hypertension [SAP = 159 (151-170) mmHg (median 1st-3rd quartiles)], 84 of normotension, SAP = 124 (113-131) mmHg and 45 of hypotension SAP = 85(80-87) mmHg. SAP were well correlated with SVR (r = 0.78, p < 0.0001) and Cvasc (r = 0.84, p < 0.0001). The PPG-based classification correlated well with SAP (r = - 0.90, p < 0.0001), SVR (r = - 0.72, p < 0.0001) and Cvasc (r = 0.82, p < 0.0001). The PPGc misclassified 7 out of the 190 episodes, presenting good accuracy (98.4% and 97.8%), sensitivity (100% and 94.9%) and specificity (97.9% and 99.2%) for detecting episodes of hypotension and hypertension, respectively. Changes in arterial pressure and vascular tone were closely related to the proposed classification based on PPG waveform.Clinical Trial Registration NTC02854852.

The Sensitivity and Specificity of Pulmonary Carbon Dioxide Elimination for Noninvasive Assessment of Fluid Responsiveness.

BACKGROUND: We sought to determine whether the response of pulmonary elimination of CO2 (VCO2) to a sudden increase in positive end-expiratory pressure (PEEP) could predict fluid responsiveness and serve as a noninvasive surrogate for cardiac index (CI). METHODS: Fifty-two patients undergoing cardiovascular surgery were included in this study. By using a constant-flow ventilation mode, we performed a PEEP challenge of 1-minute increase in PEEP from 5 to 10 cm H2O. At PEEP of 5 cm H2O, patients were preloaded with 500 mL IV saline solution after which a second PEEP challenge was performed. Patients in whom fluid administration increased CI by ≥15% from the individual baseline value were defined as volume responders. Beat-by-beat CI was derived from arterial pulse contour analysis, and breath-by-breath VCO2 data were collected during the protocol. The sensitivity and specificity of VCO2 for detecting the fluid responders according to CI was performed by the receiver operating characteristic curves. RESULTS: Twenty-one of 52 patients were identified as fluid responders (40%). The PEEP maneuver before fluid administration decreased CI from 2.65 ± 0.34 to 2.21 ± 0.32 L/min/m (P = 0.0011) and VCO2 from 150 ± 23 to 123 ± 23 mL/min (P = 0.0036) in responders, whereas the changes in CI and VCO2 were not significant in nonresponders. The PEEP challenge after fluid administration induced no significant changes in CI and VCO2, in neither responders nor nonresponders. PEEP-induced decreases in CI and VCO2 before fluid administration were well correlated (r = 0.75, P < 0.0001) but not thereafter. The area under the receiver operating characteristic curves for a PEEP-induced decrease in ΔCI and ΔVCO2 was 0.99, with a 95% confidence interval from 0.96 to 0.99 for ΔCI and from 0.97 to 0.99 for ΔVCO2. During the PEEP challenge, a decrease in VCO2 by 11% predicted fluid responsiveness with a sensitivity of 0.90 (95% confidence interval, 0.87-0.93) and a specificity of 0.95 (95% confidence interval, 0.92-0.98). CONCLUSIONS: PEEP-induced changes in VCO2 predicted fluid responsiveness with accuracy in patients undergoing cardiac surgery.

Noninvasive monitoring of lung recruitment maneuvers in morbidly obese patients: the role of pulse oximetry and volumetric capnography.

BACKGROUND: We conducted this study to determine whether pulse oximetry and volumetric capnography (VCap) can determine the opening and closing pressures of lungs of anesthetized morbidly obese patients. METHODS: Twenty morbidly obese patients undergoing laparoscopic bariatric surgery with capnoperitoneum were studied. A lung recruitment maneuver was performed in pressure control ventilation as follows: (1) During an ascending limb, the lungs' opening pressure was detected. After increasing positive end-expiratory pressure (PEEP) from 8 to 16 cm H2O, fraction of inspired oxygen (FIO2) was decreased until pulse oximetric arterial saturation (SpO2) was <92%. Thereafter, end-inspiratory pressure was increased in steps of 2 cm H2O, from 36 to a maximum of 50 cm H2O. The opening pressure was attained when SpO2 exceeded 97%. (2) During a subsequent decreasing limb, the lungs' closing pressure was identified. PEEP was decreased from 22 to 10 cm H2O in steps of 2 cm H2O. The closing pressure was determined as the PEEP value at which respiratory compliance decreased from its maximum value. We continuously recorded lung mechanics, SpO2, and VCap. RESULTS: The lungs' opening pressures were detected at 44 (4) cm H2O (median and interquartile range) and the closing pressure at 14 (2) cm H2O. Therefore, the level of PEEP that kept the lungs without collapse was found to be 16 (3) cm H2O. Using respiratory compliance as a reference, receiver operating characteristic analysis showed that SpO2 (area under the curve [AUC] 0.80 [SE 0.07], sensitivity 0.65, and specificity 0.94), the elimination of CO2 per breath (AUC 0.91 [SE 0.05], sensitivity 0.85, and specificity 0.98), and Bohr's dead space (AUC 0.83 [SE 0.06], sensitivity 0.70, and specificity 0.95] were relatively accurate for detecting lung collapse during the decreasing limb of a recruitment maneuver. CONCLUSIONS: Lung recruitment in morbidly obese patients could be effectively monitored by combining noninvasive pulse oximetry and VCap. SpO2, the elimination of CO2, and Bohr's dead space detected the individual's opening and closing pressures.

Characteristics and Evolution of Renal Transplant Recipients Infected by Carbapenemase-Producing Klebsiella pneumoniae.

BACKGROUND: Renal transplant (RT) recipients are especially susceptible to carbapenem-resistant Klebsiella pneumoniae carbapenemase (KPC) infections. However, published experience is limited. OBJECTIVE: To analyze the characteristics and evolution of RT recipients with KPC infection in our hospital. METHODS: We performed a retrospective cohort study of all RT recipients with KPC infection in our hospital from December 1, 2017 (first case), to July 31, 2019. For each RT recipient infected with KPC, 3 controls were selected. RESULTS: During the study period, 8 RT recipients presented KPC infection. Seven were detected in the first year post-RT. The most common site of infection was urine. In 2 cases the germ was isolated in blood. The number of patients with diabetes was significantly higher in the group with KPC infection (P = .023), and urologic interventions were more frequent in those patients (P = .039). No differences were found in the immunosuppressive treatment. A total of 62.5 % of patients required readmission after the KPC infection. One patient died of septicemia by KPC. In all these cases, the clone of KPC isolated was KPC ST512. CONCLUSION: KPC infection is more frequent in the first months after the RT and causes an important number of hospital admissions. It can be cause of death in RT recipients, especially in those with isolation of the germ in blood. Diabetes and urologic interventions were more frequent in this population. The analysis by molecular typing suggests exposure to a common source, highlighting the importance of preventive isolation measures and surveillance for limiting the transmission of this bacteria.

The effects of lung recruitment on the Phase III slope of volumetric capnography in morbidly obese patients.

BACKGROUND: In this study, we analyzed the effect of the alveolar recruitment strategy (ARS) and positive end-expiratory pressure (PEEP) titration on Phase III slope (S(III)) of volumetric capnography (VC) in morbidly obese patients. METHODS: Eleven anesthetized morbidly obese patients were studied. Lungs were ventilated with tidal volumes of 10 mL x kg(-1), respiratory rates of 12-14 bpm, inspiration:expiration ratio of 1:2, and FIO2 of 0.4. ARS was performed by increasing PEEP in steps of five from 0 end-expiratory pressure to 15 cm H2O. During lung recruitment, plateau pressure was limited to 50 cm H2O whereas tidal volume was increased to the ventilator's maximum value of 1400 mL, and PEEP was increased to 20 cm H2O for 2 min. Thereafter, PEEP was reduced in steps of 5 cm H2O, from 15 to 0. VC, arterial blood gases, and lung mechanics data were determined for each PEEP step. RESULTS: S(III) decreased from 0.014 +/- 0.006 to 0.005 +/- 0.005 mm Hg/mL when 0 end-expiratory pressure was compared against 15 cm H2O of PEEP after ARS (15ARS, P < 0.05). This decrement in S(III) was accompanied by increases in PaO2 (27%, P < 0.002) and compliance (32%, P < 0.001), whereas PaCO2 decreased by 8% (P < 0.038) when comparing values before and after ARS. A good prediction of the lung recruitment effect by S(III) was derived from the receiver operating characteristic curve analysis (area under the curve of 0.81, sensitivity of 0.75, and specificity of 0.74; P < 0.001). CONCLUSION: The S(III) in VC was useful to detect the optimal level of PEEP after lung recruitment in anesthetized morbidly obese patients.

Video processing analysis for the determination and evaluation of the chemotactic response in bacterial populations.

The aim of the present work was to design a methodology based on video processing to obtain indicators of bacterial population motility that allow the quantitative and qualitative analysis and comparison of the chemotactic phenomenon with different attractants in the agarose-in plug bridge method. Video image sequences were processed applying Shannon's entropy to the intensity time series of each pixel, which conducted to a final pseudo colored image resembling a map of the dynamic bacterial clusters. Processed images could discriminate perfectly between positive and negative attractant responses at different periods of time from the beginning of the assay. An index of spatial and temporal motility was proposed to quantify the bacterial response. With this index, this video processing method allowed obtaining quantitative information of the dynamic changes in space and time from a traditional qualitative assay. We conclude that this computational technique, applied to the traditional agarose-in plug assay, has demonstrated good sensitivity for identifying chemotactic regions with a broad range of motility.

Estudio de detección del riesgo en diabetes en Atención Primaria según cuestionario FINDRISC en el Municipio de Gral. Pueyrredón (Estudio DR. DIAP) / Diabetes risk detection study in Primary Care according to FINDRISC questionnaire in the Municipality of Gral. Pueyrredón (DR. DIAP STUDY)

Objetivos: conocer la magnitud del riesgo de padecer diabetes mellitus 2 (DM2) en la población del Municipio de Gral. Pueyrredón que concurre a los Centros Asistenciales de Atención Primaria. Materiales y métodos: estudio observacional para determinar el riesgo de padecer DM2 mediante una entrevista donde se indagaron sobre las ocho preguntas del cuestionario FINDRISC. Resultados: la muestra del estudio estuvo constituida por 2.784 pacientes, el 54% conformada por mujeres. La edad fue agrupada en menos de 45 años el 47,5% (1.323), de 45 a 54 años el 20,9% (582), de 55 a 64 años el 18,3% (510) y más de 64 años el 13,2% (368). El 20% de la población presentó una puntuación de la escala de riesgo del cuestionario FINDRISC igual o mayor a 15, alto riesgo a muy alto riesgo de padecer diabetes en los próximos 10 años. El 43,38% presentó un IMC>30 y el 25,97% declaró recibir medicación para la hipertensión arterial. El 55,37% refería actividad física baja, el 50,79% no ingería verduras y frutas en forma diaria y el 17,98% declaró cifras de glucemias elevadas. Las variables que con mayor frecuencia se asociaron a una escala de riesgo >15 fueron: sedentarismo (80,9%), cintura >102/88 (65,7/77,2%), antecedente de hiperglucemia (64,0%), alimentación no saludable (61,9%) e IMC>30 (61,8%). El riesgo >15 según IMC fue: IMC 30 el 45,4%. Conclusiones: el 20% de la población encuestada está en alto riesgo de padecer diabetes. Una de cada dos o tres personas sin diabetes que asisten a un centro de Atención Primaria tiene un FINDRISC >15. Esta escala de riesgo es una herramienta simple, económica, de rápida confección, no invasiva y segura para detectar individuos con alto riesgo de padecer diabetes tipo 2. También puede usarse para identificar DM2 no detectada y factores de riesgo de enfermedad cardiovascular