Regional Tissue Oxygenation Research Articles

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.

Near infrared spectroscopy tissue oxygenation in infants with bronchiolitis during mechanical ventilation and spontaneous breathing

Introduction. Near-infrared spectroscopy (NIRS) was used in infants with acute bronchiolitis as a noninvasive indicator of&nbsp;tissue oxygenation to determine regional tissue oxygen saturation (rStO2) and fractional tissue oxygen extraction (FTOE) during mechanical ventilation and spontaneous breathing.&nbsp;Methods. Twenty-seven infants with bronchiolitis that needed mechanical ventilation were included in a prospective study.&nbsp;Regional StO2 in brain, liver, kidney and skeletal muscle tissue was measured on admission to the Intensive Care Unit (ICU), on day 1 (D1); after two to three days of mechanical ventilation (D2); on the last day of mechanical ventilation (D3) and during spontaneous breathing (D4). Measurements were conducted by in-vivo optical spectroscopy. For research purposes we divided the infants according to C-reactive protein (CRP) levels, with a cut-off value of 10 mg/ml on admission, into low (l-CRP) and high (h-CRP) groups.Results. During mechanical and spontaneous breathing we found lower StO2 and higher FTOE for skeletal muscle at D4 compared to D1-D2 in the h-CRP group of patients. Differences between l- and h-CRP groups in rStO2 were found for brain tissue on D3, D4, and in rStO2 and FTOE for liver tissue on D3. A strong negative correlation was found between rStO2 and FTOE in all tissues. A positive correlation was found between CRP and rStO2 and negative between CRP and FTOE in skeletal muscle among all patients combined.&nbsp;Conclusion. Only Infants with acute bronchiolitis in the h-CRP group have significant changes in rStO2 and FTOE in skele-tal muscles during mechanical ventilation and spontaneous breathing. Regional StO2 and FTOE in all the other measured tissues never decreased below normal values.&nbsp;

Effect of Ambient Light on Near Infrared Spectroscopy

Background: Concerns have been raised about the ability of Near Infrared Spectroscopy (NIRS) to monitor skeletal tissue regional oxygen saturation (rSO2) in excessive light conditions, as are found under the overhead lights of the operating room. This study seeks to determine whether varying intensities of ambient light exert an influence on NIRS measurements of skeletal tissue rSO2. Methods: Thirty people were recruited from the staff of a local surgical center to participate in the study. Three separate NIRS devices (Covidien INVOS Cerebral Oximeter 510°C, Nonin EQUANOX Model 7600, and a CASMED MC-2030C Cerebral Oximeter) were used to obtain readings from the anterior compartment of the leg. Illuminance was recorded simultaneously with oximetry data in an operating room with (1) no lights on, (2) room lights, and (3) surgical lamps set to maximal intensity. Results: No differences were seen in rSO2 values under the different lighting conditions while using the Nonin device. There was a statistically significant difference between rSO2 for lights off versus room lights (-0.933, p=0.0045) as well as for lights off versus operating room (OR) lamps (level 5) (-0.50, p=0.0035) for the INVOS device, although the INVOS device was not always able to produce a reading in the presence of high-intensity OR light. While there was no difference found between lights off and room lights when using the CASMED device, it was unable to display a value in the presence of high-intensity OR lamp light. Conclusions: The results indicate that the presence of light has an effect on oximetry readings; however, the presence of such an effect is dependent upon the device being used. While other applications of the device, such as cerebral oximetry, may allow for drapes to cover the areas being monitored, monitoring for compartment syndrome of the leg would not be as forgiving. This application would be best served by a device capable of monitoring at all light levels.

Impact of afterload reduction strategies on regional tissue oxygenation after the Norwood procedure for hypoplastic left heart syndrome

Low cerebral tissue oxygenation saturations have been observed by near-infrared spectroscopy (NIRS) after the Norwood procedure. Altered cerebral vascular resistance and pharmacological afterload reduction redirecting blood flow away from the cerebral circulation are possible mechanisms. Two different afterload reduction strategies were evaluated in patients with hypoplastic left heart syndrome or variants after the Norwood procedure. In patients of Group 1 (n=34), afterload reduction was controlled with sodium nitroprusside or with the α-blocker phentolamine. In addition, a phosphodiesterase-III inhibitor was administered. Patients of Group 2 (n=34) received a phosphodiesterase-III inhibitor only. Cerebral and somatic tissue oxygenation saturations and routine intensive care monitoring data were recorded for 24 h before and 48 h after the Norwood procedure. Mean values of the last 4 preoperative (baseline) and of the first and last 4 postoperative hours (early and late course) were calculated. Baseline, early and late cerebral saturations were 58±7, 52±9 and 60±6% for Group 1 and 58±7, 52±12 and 61±7% for Group 2 and somatic saturations were 59±8, 76±10 and 67±9% and 58±9, 78±8 and 69±10%, respectively. Regional saturations were not different between groups. The postoperative cerebral tissue oxygen saturation was below 40% for 50 (0-1040) min in Group 1 and for 45 (0-720) min in Group 2 (P=1.00). Preoperative cerebral NIRS values (OR 0.85 [0.76-0.96], P=0.007), age at operation (OR 1.39 [1.02-1.88], P=0.034) and early postoperative diastolic blood pressure (OR 0.88 [0.78-0.99], P=0.038) were associated with cerebral tissue oxygen saturations below 40% for more than 60 min. Patients with a prolonged period of low cerebral tissue oxygen saturation had longer duration of mechanical ventilation (69 (37-192) vs 60 (33-238) h, P=0.039) and afterload reduction therapy was terminated later (95 (47-696) vs 74 (39-650) h, P=0.006). Early mortality was 9.4% (3 of 32) compared with 2.8% (1 of 36) in the remainder (P=0.336). The postoperative decline of cerebral tissue oxygen saturation was observed with both afterload reduction strategies. The difference between cerebral and somatic NIRS values may indicate a mismatch between cerebral and splanchnic oxygenation. Other strategies to improve cerebral tissue oxygenation are warranted.

Under General Anesthesia Arginine Vasopressin Prevents Hypotension but Impairs Cerebral Oxygenation During Arthroscopic Shoulder Surgery in the Beach Chair Position

Patients undergoing surgery in the beach chair position (BCP) are at a risk of cerebral ischemia. We evaluated the effect of arginine vasopressin (AVP) on hemodynamics and cerebral oxygenation during surgery in the BCP. Thirty patients undergoing shoulder surgery in BCP under propofol-remifentanil anesthesia were randomly allocated either to receive IV AVP 0.07 U/kg (AVP group, N = 15) or an equal volume of saline (control group, N = 15) 2 minutes before taking BCP. Mean arterial blood pressure (MAP), heart rate (HR), jugular venous bulb oxygen saturation (SjvO2), and regional cerebral tissue oxygen saturation (SctO2) were measured after induction of anesthesia and before (presitting in supine position) and after patients took BCP. AVP itself given before the positioning increased MAP and decreased SjvO2 and SctO2 (P < 0.0001), with HR unaffected. Although MAP was decreased by BCP in both groups, it was higher in the AVP group (P < 0.0001). While in BCP, HR remained unaltered in the control and decreased in the AVP group. SjvO2 in BCP did not differ between the groups. SctO2 was decreased by BCP in both groups, which was more pronounced in the AVP group until the end of study. The incidence of hypotension (13% vs 67%; P = 0.003) was less frequent, and that of cerebral desaturation (>20% SctO2 decrease from presitting value) (80% vs 13%; P = 0.0003) was higher in the AVP group. The incidence of jugular desaturation (SjvO2 <50%) was comparable between the groups. A prophylactic bolus administration of AVP prevents hypotension associated with BCP in patients undergoing shoulder surgery under general anesthesia. However, it was associated with regional cerebral but not jugular venous oxygen desaturation on upright positioning.

Effect of Fontan Fenestration on Regional Venous Oxygen Saturation During Exercise: Further Insights Into Fontan Fenestration Closure

Fontan fenestration closure is a topic of great debate. The body of data regarding the risks and benefits of fenestration closure is limited yet growing. Previous studies have demonstrated that Fontan patients have less exercise capacity than those with normal cardiovascular anatomy. Differences also have been noted within various subgroups of Fontan patients such as whether Fontan is fenestrated or not. This study aimed to compare trends in regional oxygen saturations using near-infrared spectroscopy (NIRS) in patients with Fontan circulations during ramping exercise to further delineate differences between patients with and without a fenestration. It was hypothesized that Fontan patients with fenestrations have better exercise times, higher absolute regional oxygen venous saturations, and smaller arteriovenous differences than Fontan patients without fenestrations. For this study, 50 consecutive Fontan patients and 51 consecutive patients with normal cardiovascular anatomy were recruited. Placement of NIRS probes was performed to obtain regional oxygen saturations from the brain and the kidney. Readings were obtained at 1-min intervals during rest, exercise, and recovery. A standard Bruce protocol was used with a 5-min recovery period. Absolute regional tissue oxygenation values (rSO2) and arterial-venous oxygen saturation differences (AVDO2) calculated as arterial oxygen saturation (SPO2)--rSO2 for normal versus Fontan patients and for fenestrated versus unfenestrated Fontan patients were compared using independent t tests. When normal and Fontan patients were compared, the Fontan patients had a significantly shorter duration of exercise (9.3 vs 13.2 min; p < 0.001). No statistically significant difference in rSO2 change or AVDO2 was evident at the time of peak exercise, at 2 min into the recovery, or at 5 min into the recovery. A small oxygen debt also was paid back to the brain in the Fontan patients after exercise, as evidenced by a narrower AVDO2 than at baseline. The comparison of Fontan patients with and without fenestration showed no statistically significant difference in exercise time, rSO2 change, or AVDO2. The Fontan patients were noted to have shorter exercise times than the normal patients and also appeared to have an alteration in postexertional regional blood flow. However, when the various Fontan subtypes were compared by presence or absence of a fenestration, no significant differences were noted with regard to change in regional oxygen saturation or arteriovenous oxygen saturation. Thus, for patients with Fontan physiology, closure of the fenestration does not seem to have an impact on the dynamics of regional oxygen extraction during exercise or recovery.

Variable alteration of regional tissue oxygen pressure in rat hippocampus by acute swimming exercise

One of the events in the brain is an increasing cerebral blood flow during exercise. The tissue oxygen level may be increased because blood flow correlates with tissue oxygen level. However, it is little known whether the tissue oxygen pressure in hippocampal region (Hip-pO2) will be affected by exercise. AimsThe aim of this study is to examine Hip-pO2 levels in the hippocampus and its changes during exercise. Main methodsWe applied improved Clark-type electrodes to measure Hip-pO2 level in the hippocampus of rats that were subjected to three groups, 2h swimming without weights (low intensity, n=6), 2h swimming with a 5g weight (moderate intensity, n=6), and 2h swimming with a 10g weight (high intensity, n=6). Key findingsExercise affected the Hip-pO2 level, the responses varied with the exercise intensity and duration. Interestingly during and after the Low intensity swimming the Hip-pO2 level showed long lasting enhancement (10–20% above resting level). But the moderate and high intensity swimming increased Hip-pO2 level at the start of the swimming (50%, P<0.05 and slightly above resting level, respectively, at 10min of 2h swimming) and then began to decrease (at 120min and 10min of 2h swimming, respectively), and suppressed the Hip-pO2 levels during post exercise resting period (2h) (85–95% of resting level, NS and 60–70% of resting level P<0.05, respectively). SignificanceWe propose that exercise-induced hippocampal hyper/hypo oxygen condition may participate in beneficial exercise effects on brain function.

Feasibility and safety of xenon compared with sevoflurane anaesthesia in coronary surgical patients: a randomized controlled pilot study

BackgroundTo date, only limited data exist about the use of xenon as an anaesthetic agent in patients undergoing cardiac surgery. The favourable cardio- and neuroprotective properties of xenon might attenuate postoperative complications, improve outcome, and reduce the incidence of delirium. Thus, the aims of this study were to investigate the feasibility and safety of balanced xenon anaesthesia in patients undergoing cardiac surgery and to gather pilot data for a future randomized multicentre study. MethodsThirty patients undergoing elective coronary artery bypass grafting were enrolled in this randomized, single-blind controlled trial. They were randomized to receive balanced general anaesthesia with either xenon (45–50 vol%) or sevoflurane (1–1.4 vol%). The primary outcome was the occurrence of adverse events (AEs). Secondary outcome parameters were feasibility criteria (bispectral index, perioperative haemodynamic, and respiratory profile) and safety parameters (dosage of study treatments, renal function, intraoperative blood loss, need for inotropic support, regional cerebral tissue oxygenation). Furthermore, at predefined time points, systemic and pulmonary haemodynamics were assessed by the use of a pulmonary artery catheter. ResultsThere were no patient characteristic differences between the groups. Patients undergoing xenon anaesthesia did not differ with respect to the incidence of AE (6 vs 8, P=0.464) compared with the sevoflurane group. No differences were detected regarding secondary feasibility and safety criteria. The haemodynamic and respiratory profile was comparable between the treatment groups. ConclusionsBalanced xenon anaesthesia is feasible and safe compared with sevoflurane anaesthesia in patients undergoing coronary artery bypass surgery. AcronymCARDIAX: A pre- and post-coronary artery bypass graft implantation disposed application of xenon. Clinical trial registrationClinicalTrials.gov: NCT01285271; EudraCT-number: 2010-023942-63. Approved by the ethics committee ‘Ethik-Kommission an der Medizinischen Fakultät der Rheinisch-Westfälischen Technischen Hochschule Aachen (RWTH Aachen)’: EK-218/10.

Reference Ranges for Regional Cerebral Tissue Oxygen Saturation and Fractional Oxygen Extraction in Neonates during Immediate Transition after Birth

To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support. The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support. A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age. We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation.

Calibration of a prototype NIRS oximeter against two commercial devices on a blood-lipid phantom

In a blood-lipid liquid phantom the prototype near-infrared spectroscopy oximeter OxyPrem was calibrated against the INVOS® 5100c adult sensor in respect to values of regional tissue oxygen haemoglobin saturation (rStO2) for possible inclusion in the randomised clinical trial - SafeBoosC. In addition different commercial NIRS oximeters were compared on changing haemoglobin oxygen saturation and compared against co-oximetry. The best calibration was achieved with a simple offset and a linear scaling of the OxyPrem rStO2 values. The INVOS adult and pediatric sensor gave systematically different values, while the difference between the NIRO® 300 and the two INVOS sensors were magnitude dependent. The co-oximetry proved unreliable on such low haemoglobin and high Intralipid levels.

The SafeBoosC Phase II Randomised Clinical Trial: A Treatment Guideline for Targeted Near-Infrared-Derived Cerebral Tissue Oxygenation versus Standard Treatment in Extremely Preterm Infants

Near-infrared spectroscopy-derived regional tissue oxygen saturation of haemoglobin (rSt<smlcap>O</smlcap>₂) reflects venous oxygen saturation. If cerebral metabolism is stable, rSt<smlcap>O</smlcap>₂ can be used as an estimate of cerebral oxygen delivery. The SafeBoosC phase II randomised clinical trial hypothesises that the burden of hypo- and hyperoxia can be reduced by the combined use of close monitoring of the cerebral rSt<smlcap>O</smlcap>₂ and a treatment guideline to correct deviations in rSt<smlcap>O</smlcap>₂ outside a predefined target range. Aims: To describe the rationale for and content of this treatment guideline. Methods: Review of the literature and assessment of the quality of evidence and the grade of recommendation for each of the interventions. Results and Conclusions: A clinical intervention algorithm based on the main determinants of cerebral perfusion-oxygenation changes during the first hours after birth was generated. The treatment guideline is presented to assist neonatologists in making decisions in relation to cerebral oximetry readings in preterm infants within the SafeBoosC phase II randomised clinical trial. The evidence grades were relatively low and the guideline cannot be recommended outside a research setting.

Cerebral, Renal, and Splanchnic Tissue Oxygen Saturation Values in Healthy Term Newborns

To determine cerebral regional tissue oxygen saturation (CrSO2), renal regional tissue oxygen saturation (RrSO2), and splanchnic regional tissue oxygen saturation (SrSO2) values in healthy term infants. Near-infrared spectroscopy was used to simultaneously measure CrSO2, RrSO2, and SrSO2 continuously for a 1-hour period on the first and second days of life. A total of 41 subjects were monitored out of which complete data were available for 38 subjects. Mean CrSO2 was 78.2 ± 7.9% on first day; 78.3 ± 6.1% on second day (p = 0.95). Mean RrSO2 was 92.1 ± 5.3% on first day; 88.9 ± 5.9% on second day (p < 0.01). Mean SrSO2 was 69.9 ± 12.1% on first day and 75.3 ± 12.4% on second day (p = 0.02). There appears to be consistency in rSO2 values in healthy newborns. CrSO2 was similar on both days. Differences observed in RrSO2 and SrSO2 between days may represent a shift in somatic blood flow distribution taking place during the first day of life.

Dynamic evaluation of near-infrared peripheral oximetry in healthy volunteers: A comparison between INVOS and EQUANOX

PurposeThe present study aimed to compare peripheral regional tissue oxygen saturation (rSO2) values and desaturation/resaturation rates given by INVOS and EQUANOX devices. Materials and methodsTwenty healthy volunteers were investigated during 4 experimental steps: baseline, hyperoxia, ischemia, and reperfusion. For each volunteer, 2 sensors INVOS and 2 sensors EQUANOX were placed on both left and right calves. Blood pressure, heart rate, and peripheral pulse oximetry were monitored. ResultsPeripheral rSO2 ranged from 40% to 95% (INVOS) and from 47% to 100% (EQUANOX): 81 ± 12 vs 82 ± 9 (P = .469). A significant relationship was found at baseline between absolute values of INVOS and EQUANOX (n = 40; R2 = 0.159; P = .011). Bias was −0.4%, and limits of agreement were ±15.1%. The percent maximum differences vs baseline values during dynamic maneuvers were 33% ± 19% (95% confidence interval, 24-42) and 21% ± 14% (95% confidence interval, 15-28) for INVOS and EQUANOX, respectively. No significant relationship was observed between percent maximum differences in INVOS and EQUANOX (n = 20; R2 = 0.128; P = .122). Rates of desaturation/resaturation during occlusive vascular tests were 3.65% per minute vs 2.36% per minute (P = .027) and 30.42% per minute vs 16.28% per minute (P = .004) for INVOS and EQUANOX, respectively. ConclusionsINVOS and EQUANOX are not comparable in measuring both absolute values and dynamic changes of peripheral rSO2 and near-infrared spectroscopy–derived parameters during occlusion vascular tests.

Cerebral oximetry values in dialyzed surgical patients: a comparison between hemodialysis and peritoneal dialysis

Background: Cerebral tissue regional oxygen saturation (rSO2) through near-infrared spectroscopy (NIRS) is a method for non-invasive monitoring of cerebral tissue oxygenation. However, nowadays there is limited information on the level of cerebral tissue oxygenation in dialyzed end-stage renal disease (ESRD) surgical patients. The aim of this observational study was to evaluate the baseline cerebral rSO2 values, to compare values between hemodialysis (HD) and peritoneal dialysis (PD) patients and identify risk factors that could predict cerebral tissue oxygenation in these patients. Patients/Methods: Thirty-two ESRD patients (≥18 years old), scheduled to undergo elective minor or major surgery, were enrolled. Patients were allocated in two groups according to dialysis modality. Twenty-three patients were treated with HD and nine were treated with PD. Demographic and clinical characteristics, comorbidities and arterial hemoglobin oxygen saturation (SpO2) of the study population were recorded. Results: Patients who were treated with HD had significant lower baseline rSO2 values compared with PD patients [median, 50% (28–63) vs. 63% (45–69), p = 0.002]. Hierarchical linear regression model analysis showed that preoperative Hb and SpO2 were positive predictive variables (B = 0.353, p = 0.01 and B = 0.375, p = 0.009, respectively) for rSO2. Moreover, dialysis modality was independent predictor for baseline rSO2. The modality of dialysis remained an independent predictor for rSO2 after controlling for the other significant variables (B = 0.291, p = 0.032) and PD was associated with higher baseline values of rSO2. Conclusion: In conclusion, ESRD surgical patients undergoing PD treatment appear to have significantly higher baseline cerebral tissue saturation values compared with HD.

Splanchnic-cerebral oxygenation ratio (SCOR) values in healthy term infants as measured by near-infrared spectroscopy (NIRS)

The splanchnic-cerebral oxygenation ratio (SCOR) is a measurement comparing regional tissue oxygen saturation of splanchnic organs and brain tissue. SCOR has been previously proposed as a marker of clinical conditions associated with gut ischemia. Our goal was to determine SCOR values in healthy neonates in their first and second days of life. Prospective observational study measuring SCOR in term neonates in the nursery using near-infrared spectroscopy (NIRS). Forty-five subjects with a mean gestational age of 39.4 ± 1.3 weeks were included. Mean SCOR on the first day was 0.90 ± 0.16 and 0.97 ± 0.16 on the second day, p = 0.02 (n = 45). No correlation was found between SCOR and gestational age; however, we did find a positive correlation between hour of life and SCOR values (r = 0.28, r(2) = 0.08, p < 0.01, two tails); SCOR appears to stabilize by 36 h. Our findings demonstrate SCOR values in healthy neonates consistent with those previously theorized and help to validate it as a diagnostic measure. In addition, we have demonstrated that SCOR values may normally be lower in infants during their first days of life, and this information may be helpful to clinicians using NIRS as a diagnostic tool.

Cerebral Near-Infrared Spectroscopy during Transition of Healthy Term Newborns

Background: Values of regional cerebral tissue oxygen saturation (cStO₂) have been described during transition of term and preterm infants after birth. However, use of different devices precludes comparison of measurements. Objective: To measure cStO₂ during transition of term infants using a calibrated 4-wavelength laser light source near-infrared spectroscopy oximeter (FORE-SIGHT) to obtain data that allow comparison with cStO₂ of very-low-birth-weight (VLBW) infants using this oximeter and with cStO₂ of term infants using different oximeters. Methods:cStO₂ (FORE-SIGHT oximeter), preductal arterial oxygen saturation and heart rate were measured in 46 healthy term infants (n = 20 spontaneous delivery, n = 22 caesarean section, n = 4 assisted vaginal delivery) during the first 10 min after delivery. Results: The median (interquartile range) cStO₂ at 2 min after birth was 42% (39-46) after spontaneous delivery, 42% (30-52) after caesarean section and 36% (20-53) after assisted vaginal delivery (no difference between groups). In association with increasing arterial oxygen saturation and heart rate, cStO₂ increased continuously and reached a steady state approximately 8 min after birth of 62-77% (interquartile range) in all three groups. Conclusions: Healthy term newborns had similar cStO₂ changes from 2 min after birth regardless of the mode of delivery. cStO₂ of healthy term infants was lower than cStO₂ of VLBW infants during transition. cStO₂ values as measured by the FORE-SIGHT oximeter seem in the range of values as measured by the NIRO 300 oximeter. They were lower than values as measured by the INVOS 5100 oximeter.

Near-infrared spectroscopy StO2 monitoring to assess the therapeutic effect of drotrecogin alfa (activated) on microcirculation in patients with severe sepsis or septic shock

BackgroundSepsis is a leading cause of death despite appropriate management. There is increasing evidence that microcirculatory alterations might persist independently from macrohemodynamic improvement and are related to clinical evolution. Future efforts need to be directed towards microperfusion monitoring and treatment. This study explored the utility of thenar muscle oxygen saturation (StO2) and its changes during a transient vascular occlusion test (VOT) to measure the microcirculatory response to drotrecogin alfa (activated) (DrotAA) in septic patients.MethodsA prospective, observational study was performed in three general intensive care units at three university hospitals. We studied 58 patients with recent onset of severe sepsis or septic shock and at least two organ dysfunctions. Thirty-two patients were treated with DrotAA and 26 were not treated because of formal contraindication. StO2 was monitored using near-infrared spectroscopy (NIRS), and VOT was performed to obtain deoxygenation (DeOx) and reoxygenation (ReOx) slopes. Measurements were obtained before DrotAA was started and were repeated daily for a 96-hour period.ResultsPatients’ characteristics, outcome, severity, and baseline values of StO2, DeOx, and ReOx did not differ between groups. Treated patients significantly improved DeOx and ReOx values over time, whereas control patients did not. In treated patients, ReOx improvements were correlated to norepinephrine dose reductions. Early clinical response (SOFA improvement after 48 hours of treatment) was not associated to changes in VOT-derived slopes. In the treated group, the relative improvement of DeOx within 48 hours was able to predict mortality (AUC 0.91, p < 0.01).ConclusionsIn patients with severe sepsis or septic shock, DrotAA infusion was associated with improvement in regional tissue oxygenation. The degree of DeOx amelioration after 2 days in treated patients predicted mortality with high sensitivity and specificity. Thus, StO2 derived variables might be useful to evaluate the microcirculatory response to treatment of septic shock.

Effect of hypoxic myocardial injury on neonatal cerebral hemodynamics and brain tissue oxygen saturation

Objective To investigate the effect of neonatal hypoxic myocardial injury and bradycardia on cerebral hemodynamics and brain tissue regional oxygen saturation (rSO2),and to provide patho-physiological evidence for treatment of neonatal hypoxic-ischemic encephalopathy (HIE) in acute phase.Methods Ninety nine full-term newborns admitted into Department of Neonatology,Peking University First Hospital from December,2005 to December,2008 were enrolled in this study.There were 18 newborns with both myocardial injury and HIE (group 1),31 newborns with HIE but without myocardial injury (group 2) and 50 cases of neonatal jaundice (control group).From 3 to 7 days after birth,Doppler ultrasound was used to measure systolic velocity (Vs),diastolic velocity (Vd) and resistance index (RI) of the anterior cerebral artery; and brain tissue rSO2 was detected by near infrared spectroscopy.The differences among groups were compared by variance analysis and LSD test.Brain tissue rSO2 before and after treatment of 20 newborns with bradycardia for various causes were detected and the difference was compared by paired t test.Results (1) Vs of group 1,group 2 and the control group was (19.35±5.13),(29.35±4.28) and (32.62±7.47) cm/s respectively; Vd was (6.43±2.98),(11.21±3.16) and (11.50±3.03) cm/s; RI was 0.68±0.10,0.62±0.03 and 0.64±0.06; brain tissue rSO2 was (52.4± 2.8)％,(54.6±3.1)％ and (62.1±1.9)％.There were significant differences among the three group(F=29.999,19.393,5.283 and 137.952,P＜0.01).Vs,Vd and rSO2 of group 1 were lower than that of group 2 and the control group (P＜0.05).RI of group 1 was higher than that of group 2 and the control group (P＜0.05).Vs and rSO2 of group 2 were lower than that of control group,but there were no differences between the two groups in Vd and RI.(2) The brain tissue rSO2 of newborns with bradycardia after treatment was higher than that before treatment [(58.7±4.6)％ vs (50.9±3.2)％,t=6.239,P＜0.01].Conclusions The disturbance of cerebral hemodynamics and cerebral oxygenation in HIE newborns are aggravated by hypoxic myocardial injury.Stable heart rate might be very important to early treatment for HIE. Key words: Anoxia; Cardiomyopathies; Bradycardia; Hemodynamics; Hypoxia-ischemia,brain; Oxygen

Monitoring of regional tissue oxygenation with near-infrared spectroscopy during the early postoperative course after superior cavopulmonary anastomosis

Near-infrared spectroscopy (NIRS) offers continuous non-invasive monitoring of regional tissue oxygenation. We evaluated NIRS monitoring during the postoperative course after superior cavopulmonary anastomosis in patients with hypoplastic left heart syndrome and anatomically related malformations. Cerebral (cSO(2)) and somatic (sSO(2)) tissue oxygenations were recorded for 48 h and compared with routine measures of intensive care monitoring. Changes in parameters in the case of postoperative complications were evaluated. Data were obtained from 32 patients. Median age at operation was 2.9 (1.5-10.0) months and weight was 5.3 ± 1.0 kg. Postoperative complications occurred in 7 patients (pulmonary artery thrombus n = 4, pneumothorax n = 1, cardiopulmonary resuscitation n = 1 and low-cardiac output n = 1). cSO(2) was 44 ± 14% at the end of the operation and reached its minimum of 40 ± 11% 2 h later (P = 0.018). Overall, cSO(2) was depressed early after surgery and increased from a mean of 42 ± 11% during the first 4 postoperative hours to 57 ± 8% in the last 4 h of the study period (P < 0.001). The sSO(2) decreased from 77 ± 11% during the early postoperative course to 68 ± 9% within the later course (P < 0.001). The cSO(2) correlated with the arterial partial pressure of oxygen (pO(2), r = 0.364, P < 0.001), with the arterial oxygen saturation (SaO(2), r = 0.547, P < 0.001) and with the central venous oxygen saturation providing the strongest correlation (SvO(2), r = 0.686, P < 0.001). Analysis of agreement between cSO(2) and SvO(2) measurements revealed a mean bias of 0.97 with limits of agreement between 19.8 and -17.9%. Inclusion of both cSO(2) and sSO(2) into a linear regression model slightly improved the prediction of SvO(2) from NIRS values (r = 0.706, P < 0.001). The mean values of cSO(2), sSO(2), SaO(2) and SvO(2) during the early postoperative period were lower in patients with complications (cSO(2): 45 ± 9 vs 29 ± 5%, P < 0.001; sSO(2): 80 ± 11 vs 70 ± 6%, P = 0.004; SaO(2): 76 ± 8 vs 66 ± 6%, P = 0.004; SvO(2): 48 ± 14 vs 32 ± 6%, P < 0.001). NIRS technology allows inferring the global oxygenation from continuous non-invasive measurements of regional tissue oxygenation. The cSO(2) is lowered in the early postoperative course. Lower cSO(2) values in the early postoperative course may be predictive of postoperative complications.

Effect of balloon atrial septostomy on cerebral oxygenation in neonates with transposition of the great arteries

The aim of this study was to determine the effect of balloon atrial septostomy (BAS) on cerebral oxygenation in neonates with transposition of the great arteries (TGA). In term neonates with TGA, regional cerebral tissue oxygen saturation (r(c)SO(2)) was measured using near-infrared spectroscopy (NIRS) for a period of 2 h, before BAS, after BAS, and 24 h after BAS. In neonates who did not require BAS on clinical grounds, r(c)SO(2) was measured within 24 h of admission and 24 h later. BAS was performed in 12 of 21 neonates. r(c)SO(2) increased from a median of 42% (before) to 48% at 2 h after BAS (P < 0.05), as did transcutaneous arterial oxygen saturation (spO(2)) (from 72% to 85%, P < 0.01). r(c)SO(2) increased further during the next 24 h (from 48% to 64%, P < 0.05), whereas spO(2) remained stable. Although beginning from a lower baseline (42 vs. 51%, P < 0.01), r(c)SO(2) was higher in neonates treated with BAS, as compared with neonates not treated with BAS, 24 h after the procedure (64 vs. 58%, P < 0.05); spO(2) was, however, similar between the two groups. BAS improves cerebral oxygen saturation in neonates with TGA. Complete recovery of cerebral oxygen saturation occurred only 24 h after BAS.