Renal rSO2 Research Articles

Effects of blood transfusion on regional tissue oxygenation in preterm newborns are dependent on the degree of anaemia.

Most of the preterm infants are transfused at least once during their stay in the neonatal intensive care unit (NICU). The aims of this study were to demonstrate if packed red blood cell (pRBC) transfusion modulates regional (cerebral, abdominal, renal) tissue oxygen saturation measured by near-infrared spectroscopy (NIRS) and to demonstrate if we can use NIRS to guide transfusion decisions in neonates. A multi-probe NIRS device was applied to anaemic preterm infants of gestational age <33 weeks for 30-60 min before and 24 h after pRBC transfusion. We evaluated the results separately in the subgroup with a pre-transfusion haemoglobin (Hb) < 8 g/dL. Cerebral, abdominal and renal tissue oxygen saturation (rSO2 ) and abdominal/cerebral, abdominal/renal and renal/cerebral rSO2 ratios before and 24 h after transfusion were compared. There was no significant difference in cerebral rSO2 and abdominal/renal rSO2 ratios before and 24 h after transfusion, but abdominal and renal rSO2 and abdominal/cerebral and renal/cerebral rSO2 ratios at the 24th h following transfusion increased significantly. This increase was observed in the subgroup with pre-transfusion Hb < 8 g/dL. Although statistically significant, the increase in renal oxygenation was within the limits of variability. The increase in tissue oxygenation in abdominal region after pRBC transfusion suggests decreased tissue oxygenation of intestines during severe anaemia despite cerebral oxygenation being maintained at that particular Hb level. The impact of the increase on renal oxygenation with pRBC transfusion is unclear and might need further investigation. Increase in abdominal rSO2 may cause reperfusion injury, oxidative damage and trigger necrotising enterocolitis.

Elevated renal tissue oxygenation in premature fetal growth restricted neonates: An observational study.

BackgroundFetal growth restriction (FGR) is associated with an increased risk for kidney disease in later life. Studies reporting on early signs of renal disturbances in FGR are sparse and mostly include invasive measurements, which limit the possibility for early identification and prevention. We aim to investigate whether renal tissue oxygen saturation (rSO2) measured with near-infrared spectroscopy (NIRS) and the derived value fractional tissue oxygen extraction (FTOE) differ between premature FGR and control neonates in the first three days after birth.MethodsNine FGR and seven control neonates born <32 weeks of gestation were included. FGR was defined as biometry <p10 combined with prenatal signs of placental insufficiency. Renal rSO2 was measured continuously with NIRS for 72 hours. FTOE was calculated as: (arterial saturation-rSO2)/arterial saturation. Renal artery blood flow (pulsatility and resistance index) was measured within 24 hours after birth. A linear mixed model approach was used (intercept ± slope = r) to analyze the NIRS parameters.ResultsRenal rSO2 was higher in FGR neonates compared to controls (94% vs. 83%; pgroup = 0.002). During the first three days after birth, renal rSO2 decreased in FGR neonates and increased in controls (r = -0.25 vs. r = 0.03; pinteraction = 0.001). Renal FTOE was lower in FGR neonates (0.02 vs. 0.14; pgroup = 0.01) and increased slightly during three days after birth, while it remained stable in controls (r = 0.003 vs. r = -0.0001; pinteraction = 0.001). Renal artery blood flow was similar between groups.ConclusionsFGR neonate kidneys showed higher rSO2 as measured with NIRS and lower derived values of FTOE in the first three days after birth. We speculate that this was caused by either a reduced oxygen consumption due to impaired renal maturation or increased renal oxygen supply. How these observations correlate with short- and long-term renal function needs further investigation before renal NIRS can be implemented in screening and prevention in clinical practice.

Effects of Neonatal Thoracoscopic Surgery on Tissue Oxygenation: A Pilot Study on (Neuro-) Monitoring and Outcomes.

Multiple reports have questioned the feasibility of neonatal thoracoscopic repair of congenital diaphragmatic hernia (CDH) and esophageal atresia (EA). The aim of this study is to examine the effects of CO2 pneumothorax on cerebral and renal rSO2 and to assess the potential predictive value of these data on neurodevelopmental outcome after neonatal thoracoscopic surgery for CDH or EA. A prospective observational pilot study. Cerebral and renal regional tissue oxyhemoglobine saturation (rSO2) rSO2 were assessed using near-infrared spectroscopy (NIRS) during thoracoscopic surgery in neonates with CDH and with EA, in addition to routine anesthesia monitoring. Cerebral and renal rSO2, linked to repeated arterial blood gas analyses, heart rate, blood pressure, and to structured longitudinal neurodevelopmental follow-up. Baseline estimated marginal means of cerebral rSO2 values (CDH: 82%, EA: 91%) did not change significantly during pneumothorax (CDH: 81%, EA 79% [n.s. versus baseline]) despite severe acidosis (lowest pH, CDH: 6.99, EA: 7.1). Neurodevelopmental outcomes at 24 months were normal in all 7 patients who were available for evaluation. Neonatal thoracoscopic repair of CDH and EA using CO2-pneumothorax leads to severe acidosis. Cerebral rSO2 remained within clinical acceptable limits during intraoperative periods of acidosis. Neurodevelopmental outcome was favorable within the first 24 months. The potential of NIRS to further improve perioperative care and long-term outcome in this specific patient group deserves further investigation.

Effects of sodium bicarbonate correction of metabolic acidosis on regional tissue oxygenation in very low birth weight neonates.

To determine the effects of sodium bicarbonate (NaHCO3) correction of metabolic acidosis on cardiopulmonary, laboratory, and cerebral, renal and splanchnic regional oxygen saturation (rSO2) and fractional tissue oxygen extraction (FTOE) in extremely premature neonates during the first postnatal week. Observational cohort data were collected from 500 to 1250 g neonates who received NaHCO3 'half' corrections (0.3 * Weight (kg) * Base Deficit (mmol l(-1))) for presumed renal losses. Twelve subjects with normal blood pressure and heart rate received 17 NaHCO3 corrections. Mean (±s.d.) gestational age was 27±2 week and birth weight was 912±157 g. NaHCO3 corrections provided a mean (±s.d.) 4.5±1.0 ml kg(-1) fluid bolus, shifted mean (±s.d.) base deficit from 7.6±1.8 to 3.4±2.1 mmol l(-1) (P<0.05), and increased median (±s.d.) pH from 7.23±0.06 to 7.31±0.05 (P<0.05). No significant changes in blood pressure, pulse oximetry, PCO2, lactate, sodium, blood urea nitrogen, creatinine or hematocrit were observed. Cerebral, renal and splanchnic rSO2 (74%, 66% and 44%, respectively, at baseline) and FTOE (0.21, 0.29 and 0.52, respectively, at baseline) were unchanged following NaHCO3 correction. NaHCO3 infusions decreased base deficits and increased pH though produced no discernible effects or benefits on cardiopulmonary parameters including rSO2 and FTOE. These findings warrant further prospective evaluation in larger populations with more significant metabolic acidosis to determine the utility of tissue oxygenation monitoring in differentiating metabolic acidosis due to oxygen delivery/consumption imbalance versus renal bicarbonate losses.

PO-0494 Longterm Multichannel Nirs Monitorization Is Feasable And Valuable In Multisystem Disease Of Term Newborns: Abstract PO-0494 Table 1

Background Near infrared spectroscopy (NIRS) is evolving into a clinical monitorization method providing information regarding not only cerebral but abdominal or renal tissue oxygenation (rSO2) as well. Fractional tissue oxygen extraction (FTOE) is calculated from NIRS measurements and arterial haemoglobin oxygen saturation (SpO2) measured by pulse oxymeter. Multichannel NIRS devices maybe very helpful in newborns with multisystem problems enabling realtime simultaneous measurements of rSO2 from different parts of the body. Pulse oxymeter integrated into a multichannel NIRS device provides simultaneous SpO2 monitoring making FTOE calculations more accurate and easier. Methods Three term newborns; 2 undergoing therapeutic hypothermia for hypoxic ischaemic encephalopathy grade II, 1 with critical pulmonary stenosis before and after cardiac surgery were monitored by multichannel NIRS (Sensmart X-100, NONIN, USA) device including cerebral, abdominal, renal rSO2 and SpO2 probes. FTOE was calculated using the equation; (SpO2-rSO2)/SpO2. Results Duration of monitorization and rSO2 and FTOE values of different body sites are presented in table with mean±SD. Discussion Longterm simultaneous monitoring of tissue oxygenation in brain, abdomen and kidneys is useful while following newborns with multisystem problems requiring hypothermia or circulatory medications to titrate the treatment accordingly. NIRS device with integrated pulse oxymeter maybe helpful for realtime calculation of FTOE to assess hemodynamics.

Intraoperative Renal Regional Oxygen Desaturation Can Be a Predictor for Acute Kidney Injury after Cardiac Surgery

To evaluate the usefulness of renal regional oxygen saturation (renal rSO2) in predicting the risk of acute kidney injury (AKI) after cardiac surgery. A prospective observational study. Tertiary care university hospital. One hundred patients undergoing cardiac surgery. Renal rSO2 was monitored continuously by near-infrared spectroscopy (NIRS) throughout the anesthetic period. Postoperative AKI was defined using the Risk, Injury, Failure, Loss, and End-stage (RIFLE) criteria. Of 95 patients who were included in the final analysis, 34 patients developed AKI after surgery. Recorded renal rSO2 data were used to calculate the total duration of the time when renal rSO2 was below the threshold values of 70%, 65%, 60%, 55%, and 50%. The total periods when the renal rSO2 level was below each of the threshold values were significantly longer in patients with AKI than in those without AKI (p = 0.001 or p<0.001). Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive power of renal rSO2 for AKI. The ROC curve analysis showed that renal rSO2 could predict the risk of AKI with statistical significance and that a renal rSO2<55% had the best performance (area under the curve-ROC, 0.777; 95% CI, 0.669-0.885; p<0.001). Multivariate logistic regression analysis revealed that AKI significantly correlated with the duration of renal rSO2<55% (p = 0.002) and logistic EuroSCORE (p = 0.007). Intraoperative renal regional oxygen desaturation can be a good predictor of AKI in adult patients undergoing cardiac surgery.

Quiescent variability of cerebral, renal, and splanchnic regional tissue oxygenation in very low birth weight neonates.

In extremely premature neonates, data concerning the normal baseline variability of near-infrared spectroscopy (NIRS)-derived regional oxygen saturation (rSO2) are lacking. We sought to determine: 1) the quiescent variability of cerebral, renal, and splanchnic rSO2 in clinically stable, undisturbed very low birth weight neonates and 2) the effects of different data averaging epochs on site-specific variability. In this prospective, observational study, neonates between 500 and 1250 g underwent seven days of continuous, real-time cerebral, renal, and splanchnic NIRS monitoring starting within the first seventy-two postnatal hours. Demographic, cardiopulmonary, bedside care, and rSO2 data were collected. rSO2 variability was analyzed utilizing data from quiescent periods identified using pre-specified stability criteria. Between- and within-monitoring site comparisons of data averaging methods were made utilizing ANOVA. Twenty-four subjects (GA 27 ± 0.3 wk, birth weight 988 ± 34 g; mean ± SEM) were monitored. Coefficients of variation (CoVar = SD/mean) were calculated for each monitoring site using varied data averaging epochs. CoVar was lowest for cerebral, intermediate for renal, and highest for splanchnic rSO2 (P < 0.01). For renal and splanchnic sites, shorter epochs (5- and 15-min) resulted in significantly smaller CoVars [P < 0.01 and P < 0.05, respectively]. Splanchnic variability was highly dependent on epoch length, ranging from 16% over 5 min to 23% over 60 min. 1) rSO2 variability differs significantly between monitoring sites and 2) shorter data sampling epochs decrease rSO2 variability. These observations may assist clinicians in operationally defining minimally significant departures to enable medical decision making utilizing this monitoring technique.

Splanchnic Oxygen Saturation Immediately After Weaning From Cardiopulmonary Bypass Can Predict Early Postoperative Outcomes in Children Undergoing Congenital Heart Surgery

This study compared the abilities of cerebral, renal, and splanchnic regional oxygen saturation (rSO2) immediately after weaning from cardiopulmonary bypass (CPB) to predict early postoperative outcomes for children undergoing congenital heart surgery. The study enrolled 73 children (ages 0.1-72 months) undergoing corrective or palliative cardiac surgery requiring CPB. Laboratory and hemodynamic variables were analyzed at the time of successful weaning from CPB. Using near-infrared spectroscopy, cerebral, renal, and splanchnic rSO2 values were obtained simultaneously. Early postoperative outcome measures included the maximum vasoactive inotropic score (VIS(max)) during the first 36 postoperative hours, the duration of mechanical ventilation, and the postoperative hospital length of stay. In the univariate analysis, cerebral, renal, and splanchnic rSO2 values correlated significantly with early postoperative outcomes. However, splanchnic rSO2 was the only independent factor predicting VIS(max) (β = -0.302, P = 0.021), duration of mechanical ventilation (β = -0.390, P = 0.002), and postoperative hospital length of stay (β = -0.340, P = 0.001) by multivariate analyses. Splanchnic rSO2 had a larger receiver operating characteristic area under the curve (AUC) for determining high VIS(max), prolonged mechanical ventilation, and longer postoperative hospital stay (AUC 0.775, 0.792, and 0.776, respectively) than cerebral (AUC 0.630, 0.638, and 0.632, respectively) and renal (AUC 0.703, 0.716, and 0.715, respectively) rSO2. After weaning from CPB, splanchnic rSO2 may be superior to rSO2 measured from brain and kidney in predicting an increased requirement for vasoactive inotropic support, a prolonged mechanical ventilation, and a longer postoperative hospital stay for children.

Normal cerebral, renal and abdominal regional oxygen saturations using near-infrared spectroscopy in preterm infants

Objective:The aim of this study is to characterize baseline regional oxygen saturations (rSO2) in stable preterm infants during the first weeks of life.Study Design:Cerebral, renal and abdominal rSO2 were continuously monitored from the time of birth to 21 days in twelve preterm infants of 29–34 weeks gestation. Regional saturations were evaluated for trends over time, variability and differences between gestational ages (GAs) and reported pediatric values.Result:Both cerebral (66–83%) and renal (64–87%) rSO2 baselines were within the range of reported neonatal values but consistently decreased over the first weeks of life (P<0.01). The baseline abdominal rSO2 was 32–66% and increased with GA (P=0.05). The rSO2 variability was lowest for cerebral measurements and highest at the abdomen. Abdominal rSO2 variability decreased over time (P⩽0.05).Conclusion:Daily baseline rSO2 in preterm infants changes over the first weeks of life, especially at the abdomen. Evolution in baseline rSO2 over time may indicate regional developmental maturation of physiological oxygen balance.

Utility Of Near Infrared Spectroscopy (nirs) Guided Tilt Table Testing.

Syncope is transient loss of consciousness. Neurocardiogenic syncope is the most common cause of syncope. Confirmation of the diagnosis of syncope is based on the head-up tilt table test. Near-infrared spectroscopy (NIRS) is a monitor of regional oxygenation and is helpful in predicting cerebral and renal ischemia. PURPOSE: Determine if multi-site NIRS monitoring will reveal differential desaturation patterns in the brain and renal vascular beds during postural stresses. METHODS: All patients (7-21 years old) scheduled to undergo tilt table testing were recruited. NIRS measurements were obtained at the forehead and above the left paravertebral level at the T10 to L1space. Tissue saturations (rSO2) were recorded at rest, during tilt test and throughout recovery. All data routinely obtained during tilt table testing (i.e. HR, BP) were included in the research database. RESULTS: 20 patients were recruited. Average age of the group was 12.9 years. 7 patients had a positive tilt table test. Patients with syncope had rSO2 trends distinctly different form non-fainters. In these patients, cerebral rSO2 shows a sudden abrupt decrease from hypo perfusion, which was followed by various progressive clinical symptoms. Cerebral rSO2 trend was paralleled by a dramatic increase in renal rSO2. These rSO2 trends are progressive until patient is returned to supine position with normalization of rSO2 thereafter. CONCLUSION: Multi-site NIRS guided tilt table testing revealed dramatic desaturation patterns in the vascular beds during postural gravitational stresses that preceded physiologic symptoms. These patterns underlie the systemic oxygen consumption to flow-coupling dynamics observed during syncope.

Near Infrared Spectroscopy: Guided Tilt Table Testing for Syncope

Syncope is transient loss of consciousness. Neurocardiogenic syncope (NCS) is the most common cause of syncope. Head-up tilt-table test (HUTT) has been used to demonstrate physiologic events during graded orthostatic challenge in individuals with significant handicap from NCS. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor trends of regional tissue oxygenation (rSO2). We hypothesize that multisite NIRS monitoring will show differential desaturation patterns in the brain and renal vascular beds during postural stresses. All patients age 7-21 years old scheduled to undergo HUTT were recruited. Two probes for NIRS monitoring were placed on the forehead and above the left paravertebral level at the T10 to L1 space. These leads were attached to the Somanetics monitor (Somanetics, Troy MI). Tissue saturations (rSO2) obtained at two sites were recorded at rest, during the test, and throughout a 5-min recovery period. All data routinely obtained in HUTT were included in the research study database. Thirteen patients were recruited. The average age was 12.9 years. Five patients had a positive tilt-table test. The patients with syncope had rSO2 trends distinctly different from the normal subjects. In these patients, cerebral rSO2 showed a sudden decreasing trend from hypoperfusion, soon followed by various clinical symptoms. The cerebral rSO2 trend, which showed a dramatic increase, was paralleled by renal rSO2. These rSO2 trends were progressive until the patient was brought back to the supine position, which resulted in the rSO2 in both beds returning to baseline. Multisite NIRS-guided HUTT shows differential trends in the different vascular beds during postural gravitational stresses, and these patterns underlie the systemic oxygen consumption to flow-coupling dynamics observed during syncope.

Multisite Near-Infrared Spectroscopy Predicts Elevated Blood Lactate Level in Children After Cardiac Surgery

To determine if a relationship exists between regional oxyhemoglobin saturation (rSO(2)) measured at various body locations by near-infrared spectroscopy (NIRS) and blood lactate level in children after cardiac surgery. A prospective, observational study. A pediatric cardiac intensive care unit in a university hospital. Twenty-three children undergoing repair of congenital heart disease. Patients with single-ventricle physiology and/or residual intracardiac shunts were excluded. None. Cerebral, splanchnic, renal, and muscle rSO(2) values were recorded every 30 seconds via NIRS for 24 hours postoperatively. Blood lactate levels measured minimally at 0, 2, 4, 6 and 24 hours postoperatively were correlated with rSO(2) values derived by averaging all values recorded during the 60 minutes preceding the blood draw. Twenty-three patients were enrolled with 163 lactate measurements and more than 39,000 rSO(2) observations analyzed. Cerebral rSO(2) had the strongest inverse correlation with lactate level followed by splanchnic, renal, and muscle rSO(2) (r = -0.74, p < 0.0001, r = -0.61, p < 0.0001, r = -0.57, p < 0.0001, and r = -0.48, p < 0.0001, respectively). The correlation improved by averaging the cerebral and renal rSO(2) values (r = -0.82, p < 0.0001). Furthermore, an averaged cerebral and renal rSO(2) value <or=65% predicted a lactate level >or=3.0 mmol/L with a sensitivity of 95% and a specificity of 83% (p = 0.0001). Averaged cerebral and renal rSO(2) less than 65% as measured by NIRS predicts hyperlactatemia (>3 mmol/L) in acyanotic children after congenital heart surgery. Hence, this noninvasive, continuous monitoring tool may facilitate the identification of global hypoperfusion caused by low cardiac output syndrome in this population.

Correlation of abdominal site near-infrared spectroscopy with gastric tonometry in infants following surgery for congenital heart disease*

Splanchnic oximetry, as measured by near-infrared spectroscopy (NIRS), correlates with gastric tonometry as a means of assessing regional (splanchnic) oxygenation and perfusion. Prospective, data-gathering study. Pediatric cardiac intensive care unit in a tertiary care children's hospital. Neonates and infants with congenital heart disease who underwent catheter intervention or surgical repair requiring cardiopulmonary bypass. None. Twenty neonates and infants were studied within 48 hrs of surgery. We measured somatic saturation (rSO2) via NIRS sensors placed over the anterior abdomen (splanchnic bed) and dorsal lateral flank (renal bed). Somatic rSO2 readings were paired with simultaneous points of intramucosal gastric pH (pHi), measured by tonometry. The rSO2 readings were paired with serum lactate and measurements of systemic mixed venous saturation (SVO2). There was strong correlation between the abdominal rSO2 and pHi (r = .79; p < .0001) as well as between abdominal rSO2 and SVO2 (r = .89; p < .0001). There was also significant negative correlation between the abdominal rSO2 and serum lactate (r = .77; p < .0001). Correlations between the dorsal lateral (renal) rSO2 measurements and serum lactate and SVO2 were also significant but not as strong. Abdominal site rSO2, measured in infants with either single or biventricular physiology, exhibits a strong correlation with gastric pHi as well as with serum lactate and SVO2. The results indicate that rSO2 measurements over the anterior abdominal wall correlate more strongly than flank rSO2 with regard to systemic indices of oxygenation and perfusion. This study suggests that the NIRS monitor is a valid modality to obtain an easy, immediate, and noninvasive measurement of splanchnic rSO2 in infants following cardiac surgery for congenital heart disease.