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Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery.

ABSTRACT: OBJECTIVES:The effects of hypercapnia on regional cerebral oxygen saturation (rSO2) during surgery are unclear. We conducted a randomised controlled trial to investigate the relationship between mild hypercapnia and rSO2. We hypothesised that, compared with targeted normocapnia (TN), targeted mild hypercapnia (TMH) during major surgery would increase rSO2. DESIGN:A prospective, randomised, controlled trial in adult participants undergoing elective major surgery. SETTING:A single tertiary centre in Heidelberg, Victoria, Australia. PARTICIPANTS:40 participants were randomised to either a TMH or TN group (20 to each). INTERVENTIONS:TMH (partial pressure of carbon dioxide in arterial blood, PaCO2, 45-55?mm Hg) or TN (PaCO2 35-40?mm Hg) was delivered via controlled ventilation throughout surgery. PRIMARY AND SECONDARY OUTCOME MEASURES:The primary endpoint was the absolute difference between the two groups in percentage change in rSO2 from baseline to completion of surgery. Secondary endpoints included intraoperative pH, bicarbonate concentration, base excess, serum potassium concentration, incidence of postoperative delirium and length of stay (LOS) in hospital. RESULTS:The absolute difference between the two groups in percentage change in rSO2 from the baseline to the completion of surgery was 19.0% higher in both hemispheres with TMH (p<0.001). On both sides, the percentage change in rSO2 was greater in the TMH group than the TN group throughout the duration of surgery. The difference between the groups became more noticeable over time. Furthermore, postoperative delirium was higher in the TN group (risk difference 0.3, 95%?CI 0.1 to 0.5, p=0.02). LOS was similar between groups (5 days vs 5 days; p=0.99). CONCLUSION:TMH was associated with a stable increase in rSO2 from the baseline, while TN was associated with a decrease in rSO2 in both hemispheres in patients undergoing major surgery. This resulted in a clear separation of percentage change in rSO2 from the baseline between TMH and TN over time. Our findings provide the rationale for larger studies on TMH during surgery. TRIAL REGISTRATION NUMBER:The Australian New Zealand Clinical Trials Registry (ACTRN12616000320459).

SUBMITTER: Wong C

PROVIDER: S-EPMC7045198 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery.

Wong Clarence C Churilov Leonid L Cowie Dean D Tan Chong Oon CO Hu Raymond R Tremewen David D Pearce Brett B Pillai Param P Karalapillai Dharshi D Bellomo Rinaldo R Weinberg Laurence L

BMJ open 20200216 2

<h4>Objectives</h4>The effects of hypercapnia on regional cerebral oxygen saturation (rSO<sub>2</sub>) during surgery are unclear. We conducted a randomised controlled trial to investigate the relationship between mild hypercapnia and rSO<sub>2</sub>. We hypothesised that, compared with targeted normocapnia (TN), targeted mild hypercapnia (TMH) during major surgery would increase rSO<sub>2</sub>.<h4>Design</h4>A prospective, randomised, controlled trial in adult participants undergoing elective ...[more]

PMID: 32066598

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Project description:PurposeA previous study reported that low baseline cerebral oxygen saturation (ScO2) (?50%) measured with near-infrared spectroscopy was predictive of poor clinical outcomes after cardiac surgery. However, such findings have not been reconfirmed by others. We conducted the current study to evaluate whether the previous findings would be reproducible, and to explore mechanisms underlying the ScO2-based outcome prediction.MethodsWe retrospectively investigated 573 consecutive patients, aged 20 to 91 (mean ± standard deviation, 67.1 ± 12.8) years, who underwent major cardiovascular surgery. Preanesthetic baseline ScO2, lowest intraoperative ScO2, various clinical variables, and hospital mortality were examined.ResultsBivariate regression analyses revealed that baseline ScO2 correlated significantly with plasma brain natriuretic peptide concentration (BNP), hemoglobin concentration (Hgb), estimated glomerular filtration rate (eGFR), and left ventricular ejection fraction (LVEF) (p < 0.0001 for each). Baseline ScO2 correlated with BNP in an exponential manner, and BNP was the most significant factor influencing ScO2. Logistic regression analyses revealed that baseline and lowest intraoperative ScO2 values, but not relative ScO2 decrements, were significantly associated with hospital mortality (p < 0.05), independent of the EuroSCORE (p < 0.01). Receiver operating curve analysis of ScO2 values and hospital mortality revealed an area under the curve (AUC) of 0.715 (p < 0.01) and a cutoff value of ?50.5% for the baseline and ScO2, and an AUC of 0.718 (p < 0.05) and a cutoff value of ?35% for the lowest intraoperative ScO2. Low baseline ScO2 (?50%) was associated with increases in intubation time, intensive care unit stay, hospital stay, and hospital mortality.ConclusionBaseline ScO2 was reflective of severity of systemic comorbidities and was predictive of clinical outcomes after major cardiovascular surgery. ScO2 correlated most significantly with BNP in an exponential manner, suggesting that BNP plays a major role in the ScO2-based outcome prediction.

Project description:BackgroundNear-infrared spectroscopy monitoring of cerebral oxygen saturation (rSo(2)) has become routine in many centers, but no studies have reported the relationship of intraoperative near-infrared spectroscopy to long-term neurodevelopmental outcomes after cardiac surgery.Methods and resultsOf 104 infants undergoing biventricular repair without aortic arch reconstruction, 89 (86%) returned for neurodevelopmental testing at 1 year of age. The primary near-infrared spectroscopy variable was the integrated rSo(2) (area under the curve) for rSo(2) <or=45%; secondary variables were the average and minimum rSo(2) by perfusion phase and at specific time points. Psychomotor and mental development indexes of the Bayley scales, head circumference, neurological examination, and abnormalities on brain magnetic resonance imaging did not differ between subjects according to a threshold level for rSo(2) of 45%. Lower Psychomotor Development Index scores were modestly associated with lower average (r=0.23, P=0.03) and minimum (r=0.22, P=0.04) rSo(2) during the 60-minute period after cardiopulmonary bypass but not with other perfusion phases. Hemosiderin foci on brain magnetic resonance imaging were associated with lower average rSo(2) from postinduction to 60 minutes post cardiopulmonary bypass (71+/-10% versus 78+/-6%, P=0.01) and with lower average rSO(2) during the rewarming phase (72+/-12% versus 83+/-9%, P=.003) and during the 60-minute period following cardiopulmonary bypass (65+/-11% versus 75+/-10%, P=0.009). In regression analyses that adjusted for age <or=30 days, Psychomotor Development Index score (P=0.02) and brain hemosiderin (P=0.04) remained significantly associated with rSo(2) during the 60-minute period following cardiopulmonary bypass.ConclusionsPerioperative periods of diminished cerebral oxygen delivery, as indicated by rSo(2), are associated with 1-year Psychomotor Development Index and brain magnetic resonance imaging abnormalities among infants undergoing reparative heart surgery. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00006183.

Project description:ObjectivesTo investigate the indications of high-flow nasal cannula (HFNC) oxygen therapy among patients with mild hypercapnia and to explore the predictors of intubation when HFNC fails.MethodsThis retrospective study was conducted based on the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Adult patients with mild hypercapnia (45 < PaCO2 ≤ 60 mmHg) received either HFNC or non-invasive ventilation (NIV) oxygen therapy. Propensity score matching (PSM) was implemented to increase between-group comparability. The Kaplan-Meier method was used to estimate overall survival and cumulative intubation rates, while 28-day mortality and 48-h and 28-day intubation rates were compared using the Chi-squared test. The predictive performances of HR/SpO2 and the ROX index (the ratio of SpO2/FiO2 to respiratory rate) at 4 h were assessed regarding HFNC failure, which was determined if intubation was given within 48 h after the initiation of oxygen therapy. The area under the receiver operating characteristic curve (AUC) for HR/SpO2 and the ROX index were calculated and compared.ResultsA total of 524,520 inpatient hospitalization records were screened, 106 patients in HFNC group and 106 patients in NIV group were successfully matched. No significant difference in 48-h intubation rate between the HFNC group (the treatment group) and the NIV group (the control group) (14.2% vs. 8.5%, p = 0.278); patients receiving HFNC had higher 28-day intubation rate (26.4% vs. 14.2%, p = 0.029), higher 28-day mortality (17.9% vs. 8.5%, p = 0.043), and longer ICU length of stay (4.4 vs. 3.3 days, p = 0.019), compared to those of NIV group. The AUC of HR/SpO2 at 4 h after the initiation of HFNC yielded around 0.660 for predicting 48-h intubation, greater than that of the ROX index with an AUC of 0.589 (p < 0.01).ConclusionPatients with impending respiratory failure had lower intubation rate, shorter ICU length of stay, and lower mortality when treated mild hypercapnia with NIV over HFNC. As opposed to the ROX index, a modest, yet improved predictive performance is demonstrated using HR/SpO2 in predicting the failure of HFNC among these patients.

Project description:ObjectiveTo investigate whether monitoring of cerebral tissue oxygen saturation using near infrared spectroscopy in addition to routine monitoring combined with defined treatment guidelines during immediate transition and resuscitation increases survival without cerebral injury of premature infants compared with standard care alone.DesignMulticentre, multinational, randomised controlled phase 3 trial.Setting11 tertiary neonatal intensive care units in six countries in Europe and in Canada.Participants1121 pregnant women (<32 weeks' gestation) were screened prenatally. The primary outcome was analysed in 607 of 655 randomised preterm neonates: 304 neonates in the near infrared spectroscopy group and 303 in the control group.InterventionPreterm neonates were randomly assigned to either standard care (control group) or standard care plus monitoring of cerebral oxygen saturation with a dedicated treatment guideline (near infrared spectroscopy group) during immediate transition (first 15 minutes after birth) and resuscitation.Main outcome measureThe primary outcome, assessed using all cause mortality and serial cerebral ultrasonography, was a composite of survival without cerebral injury. Cerebral injury was defined as any intraventricular haemorrhage or cystic periventricular leukomalacia, or both, at term equivalent age or before discharge.ResultsCerebral tissue oxygen saturation was similar in both groups. 252 (82.9%) out of 304 neonates (median gestational age 28.9 (interquartile range 26.9-30.6) weeks) in the near infrared spectroscopy group survived without cerebral injury compared with 238 (78.5%) out of 303 neonates (28.6 (26.6-30.6) weeks) in the control group (relative risk 1.06, 95% confidence interval 0.98 to 1.14). 28 neonates died (near infrared spectroscopy group 12 (4.0%) v control group 16 (5.3%): relative risk 0.75 (0.33 to 1.70).ConclusionMonitoring of cerebral tissue oxygen saturation in combination with dedicated interventions in preterm neonates (<32 weeks' gestation) during immediate transition and resuscitation after birth did not result in substantially higher survival without cerebral injury compared with standard care alone. Survival without cerebral injury increased by 4.3% but was not statistically significant.Trial registrationClinicalTrials.gov NCT03166722.

Project description:BackgroundThe function and viability of the brain depend on adequate oxygen supply. A decrease in cerebral blood supply causing cerebral desaturation may lead to many neurological complications. Direct measurement of regional cerebral oxygen saturation (rScO2) assists in early detection and management. Near-infrared spectroscopy (NIRS) has been introduced for measuring rScO2. A pair of sensors are attached to the right and left forehead. However, there are some situations where the forehead of the patient is not accessible for sensor attachment (e.g., neurosurgery involving the frontal area; a bispectral index (BIS) sensor already attached, or a wound to the forehead); therefore, alternate sites for sensor attachment are required. The temporal area was proposed as an alternate site. The objective of this study was to assess the correlation and agreement of rScO2 measured at the forehead vs. the temporal area.MethodsAdult patients undergoing cardiothoracic or vascular surgery were monitored for rScO2 using two pairs of ForeSight sensors. The first pair (A1 and A2) were attached to the right and left forehead, while the second pair (B1 and B2) were attached to the right and left temporal area. The rScO2 values measured from A1 vs. B1 and A2 vs. B2 were assessed for correlation and agreement using the Bland-Altman analysis.ResultsData from 19 patients with 14,364 sets of data were analyzed. The data from A1 vs. B1 and A2 vs. B2 showed moderate positive correlation (r = 0.627; P < 0.0001 and r = 0.548; P < 0.0001). The biases of A1 vs. B1 and A2 vs. B2 were -2.3% (95% CI [-2.5 to -2.2]; P < 0.0001) and 0.7% (95% CI [0.6-0.8]; P < 0.0001). The lower and upper limits of agreement of A1 vs. B1 were -17.5% (95% CI [-17.7 to -17.3]) and 12.8% (95% CI [12.6-13.0]). The lower and upper limits of agreement of A2 vs. B2 were -14.6% (95% CI [-14.8 to -14.4]) and 16.0% (95% [CI 15.8-16.3]).ConclusionsThe rScO2 values measured from sensors at the frontal and temporal areas show a moderate correlation with sufficiently good agreement. The temporal area may be an alternative to the frontal area for cerebral oximetry monitoring.

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Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery.

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Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery.

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