Baseline cerebral oximetry values in elderly patients with hip fractures: a prospective observational study

Low preoperative regional cerebral oxygen saturation in hemodialysis patients

Background

Regional cerebral oxygen saturation (rSO₂) monitoring by near-infrared spectroscopy provides valuable information regarding cerebral oxygen delivery, and it has been increasingly used in cardiovascular surgery. Although it has been shown that dialysis-dependent patients [hemodialysis (HD) patients] suffer from low cerebral perfusion, limited information is available on cerebral tissue oxygenation levels in HD patients.

Findings

In this retrospective study, the preoperative rSO₂ values in 9 HD patients undergoing coronary artery bypass graft surgery were compared with those in 40 non-HD patients. HD patients had lower preoperative rSO₂ values than non-HD patients (median: 46 vs. 68%, respectively, P < 0.001). Despite adjusting for age, hemoglobin concentration, and left ventricular ejection fraction using multivariable linear regression, HD showed a strong association with low rSO₂ (estimated coefficient: −20.4, P < 0.001).

Conclusions

HD showed a strong association with low preoperative rSO₂ values in patients undergoing coronary artery bypass graft surgery, even after adjusting for known factors that affect rSO₂ values, including age, hemoglobin concentration, and cardiac systolic function. Further research is required to elucidate the mechanisms decreasing rSO₂ values in HD patients.

Sevoflurane preserves regional cerebral oxygen saturation better than propofol: Randomized controlled trial

STUDY OBJECTIVE

To investigate possible effects of volatile induction and maintenance anesthesia with sevoflurane (VIMA) and total intravenous anesthesia with propofol (TIVA) on regional cerebral oxygen saturation (rcSo₂) during laparoscopic cholecystectomy.

DESIGN

Randomized, prospective and single-blinded study.

SETTING

Academic hospital.

PATIENTS

ASA physical status of I and II surgical patients, scheduled for elective laparoscopic cholecystectomy from March 2013 to October 2014.

MEASUREMENTS

Changes of regional cerebral oxygen saturation were measured by near-infrared spectroscopy on the left and right sides of forehead at different time points: before anesthesia induction (Tbas), immediately after induction (Tind), after applaying a pneumoperitoneum (TCo₂), 10 minutes after positioning the patient into reverse Trendelenburg's position (TrtCo₂), immediately after desufflation of gas (Tpost) and 30 (Trec30) and 60 (Trec60) minutes after emergence from anesthesia.

MAIN RESULTS

Study population included 124 patients, 62 in each group. There was no significant difference between these groups according to demographic characteristics, surgery and anesthesia times as well as in the basal rcSo₂ values. Statistically higher rSco₂ values were noted in the VIMA group when compared to the TIVA group in all time points Tind, TCo₂, TrtCo₂, Tpost, Trec30 and Trec60 and incidence of critical rcSo₂ decreases was statistically lower in VIMA group (P<.05). There were no serious perioperative complications.

CONCLUSIONS

VIMA technique provides significantly (4%-11%) higher rcSO₂ values during general anesthesia for laparoscopic cholecystectomy, when compared with TIVA and also provides significantly less number of critical rcSO₂ decreases.

The relationship between carotid artery colour Doppler finding and cerebral oximetry

BACKGROUND

In some cases, permanent reduction in cerebral functioning affects a high percentage of patients undergoing cardiovascular surgery. We studied the relationship between the results of preoperative bilateral carotid artery colour Doppler sonography and regional cerebral oxygen saturation (rSO2) during coronary artery bypass graft surgery (CABG).

MATERIALS AND METHODS

This study was a cross-sectional analytical study conducted with 96 candidates for off-pump CABG. This study determined the percentage of the correlation of rSO2 with demographic information, diabetes, hyperlipidemia, hypertension, myocardial infraction (MI), and smoking, and also provided information on the presence and type of plaque, intima-media thickness (IMT), and percentage of stenosis of carotid artery detected through colour Doppler sonography. Data were analyzed by the t-test, the Chi-square test, and simple linear regression.

RESULTS

In this study, the mean value of rSO2 increased after intubation compared to the mean before intubation, the difference being statistically significant (P = 0.005). A comparison of the mean rSO2 of the right side of the brain and the percentage of right carotid obstruction (stenosis of less than 50% vs. stenosis with a range of 50-69%) revealed that the mean rSO2 at the time of the partial-clamp between carotid stenosis less than 50% and carotid stenosis with a range of 50-69% was statistically significant (P = 0.043).

CONCLUSIONS

There is no statistically significant correlation between rSO2 and percentage of carotid artery stenosis less than 70%. It is advised that rSO2 and carotid stenosis of greater than 70% be studied in future.

Monitoring of brain oxygen saturation (INVOS) in a protocol to direct blood transfusions during cardiac surgery: a prospective randomized clinical trial

Background

Blood transfusions are common in cardiac surgery, but have been associated with increased morbidity and long-term mortality. Efforts to reduce blood product use during cardiac surgery include fluid restriction to minimize hemodilution, and protocols to guide transfusion decisions. INVOS is a modality that monitors brain tissue oxygen saturation, and could be useful in guiding decisions to transfuse. However, the role of INVOS (brain tissue oxygen saturation) as part of an algorithm to direct blood transfusions during cardiac surgery has not been evaluated. This study was conducted to investigate the value of INVOS as part of a protocol for blood transfusions during cardiac surgery.

Methods

Prospective, randomized, blinded clinical trial, on 150 (75 per group) elective cardiac surgery patients. The study was approved by the Institution Ethics committee and all patients gave written informed consent. Data were initially analyzed based on “intention to treat”, but subsequently were also analyzed “per protocol”.

Results

When protocol was strictly followed (“per protocol analysis”), compared to the control group, significantly fewer patients monitored with INVOS received any blood transfusions (46 of 70 patients in INVOS group vs. 55 of 67 patients in the control group, p = 0.029). Similarly, patients monitored with INVOS received significantly fewer units of red blood cell transfusions intraoperatively (0.20 ± 0.50 vs. 0.52 ± 0.88, p = 0.008) and overall during hospital stay (1.31 ± 1.20 vs. 1.82 ± 1.46, p = 0.024). When data from all patients (including patient with protocol violation) were analyzed together (“intention to treat analysis”), the observed reduction of blood transfusions in the INVOS group was still significant (51 of 75 patients transfused in the INVOS group vs. 63 of 75 patients transfused in the control group, p = 0.021), but the overall number of units transfused per patient did not differ significantly between the groups (1.55 ± 1.97 vs. 1.84 ± 1.41, p = 0.288).

Conclusions

Our data suggest that INVOS could be a useful tool as part of an algorithm to guide decisions for blood transfusion in cardiac surgery. Additional data from rigorous, well designed studies are needed to further evaluate the role of INVOS in guiding blood transfusions in cardiac surgery, and circumvent the limitations of this study.

Trial registration

ClinicalTrials.gov: NCT00879463

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.

The effect of tourniquet deflation on hemodynamics and regional cerebral oxygen saturation in aged patients undergoing total knee replacement surgery

BACKGROUND

Inflation and deflation of a pneumatic tourniquet used in total knee replacement surgery induces various changes in patient's hemodynamic and metabolic status, which may result in serious complications, especially in aged patients. Near-infrared spectroscopy (NIRS) is a monitoring device designed to estimate the regional cerebral oxygen saturation. We evaluated the effect of tourniquet deflation on hemodynamics and regional cerebral oxygen saturation in aged patients undergoing total knee replacement surgery, using NIRS.

METHODS

Twenty-eight American Society of Anesthesiologists physical status I or II patients, over the age of sixty-five years undergoing total knee replacement surgery, were included. Under general anesthesia, the mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), and regional cerebral oxygen saturation (rSO(2)) were recorded before induction of anesthesia and every 2 min after tourniquet deflation for 20 min. Arterial blood gas analysis was performed 5 min before, in addition to 0, and 10 min after tourniquet deflation.

RESULTS

The decrease of rSO(2) was not significant during 20-min deflation period. MAP, CO and SV showed significant decrease during 2 to 12, 4 to 6 and 2 to 6-min period after tourniquet deflation, respectively (P < 0.05). There was no relationship between a maximal decrease of MAP and rSO(2).

CONCLUSIONS

In aged patients undergoing total knee replacement surgery under general anesthesia, tourniquet deflation caused significant changes in hemodynamic and metabolic status, but not in regional cerebral oxygen saturation. It is recommended to monitor neurologic status, as well as hemodynamic and metabolic status to avoid serious complications, especially in aged patients.