Biomedical subjects

Eckehard A Stuth

Publications and source records attributed to Eckehard A Stuth.

4 recordsLinked to original sources

PubMed2006

Near infrared spectroscopy monitoring during pediatric aortic coarctation repair.

BACKGROUND: Near infrared spectroscopy (NIRS) measures regional tissue oxygenation continuously and noninvasively and may allow assessment of changes in regional perfusion in real time. METHODS: We used NIRS monitoring to track real-time changes in regional oxygenation (rSO2) above and below the aortic cross-clamp in patients undergoing aortic coarctation repair and routinely stored these data in an operative electronic data base. This allowed us to analyze the changes in rSO2 during aortic coarctation repair for three pediatric age groups (neonates, infants <1 year, and children >1 year). Two site [cerebral (rSO2-C) and somatic thoracodorsal (rSO2-S)] rSO2 monitoring was performed in patients undergoing aortic coarctation repair. Data for rSO2 were analyzed across sites and age groups before, during and after cross-clamp. RESULTS: Twenty-six patients were available for analysis (11 neonates, 5 infants and 10 children). The regional oxygenation below the cross clamp (rSO2-S) declined significantly in all three age groups, but the decrease in neonates and infants <1 year of age was significantly greater than in the older children. CONCLUSIONS: Monitoring rSO2-S provides real-time trend information of regional oxygenation below the aortic cross-clamp. The decline in rSO2-S during aortic cross-clamp was rapid and large in most neonates and young infants <1 year which suggests impairment of regional perfusion presumably because of a lack of adequate collateral circulation to the monitored regional tissue. In contrast, the rSO2-S changed only to a minor degree in most infants and children >1 year, possibly because they had time to develop a more adequate collateral circulation around incomplete aortic obstruction.

Adolescent↗

PubMed2004

Changes in cerebral and somatic oxygenation during stage 1 palliation of hypoplastic left heart syndrome using continuous regional cerebral perfusion.

OBJECTIVES: Stage 1 palliation of hypoplastic left heart syndrome requires the interruption of whole-body perfusion. Delayed reflow in the cerebral circulation secondary to prolonged elevation in vascular resistance occurs in neonates after deep hypothermic circulatory arrest. We examined relative changes in cerebral and somatic oxygenation with near-infrared spectroscopy while using a modified perfusion strategy that allowed continuous cerebral perfusion. METHODS: Nine neonates undergoing stage 1 palliation for hypoplastic left heart syndrome had regional tissue oxygenation continuously measured by frontal cerebral and thoraco-lumbar (T10-L2) somatic (renal) reflectance oximetry probes (rSO(2), INVOS; Somanetics, Troy, Mich). Surgery was accomplished using cardiopulmonary bypass with whole-body cooling (18 degrees C-20 degrees C) and regional cerebral perfusion through the innominate artery at flow rates guided by estimated minimum flow requirements and measured rSO(2) during reconstruction of the aortic arch. Data were logged at 1-minute intervals and analyzed using repeated measures analysis of variance. RESULTS: A total of 3176 minutes of data were analyzed. Prebypass cerebral rSO(2) was 65.4 +/- 8.9, and somatic rSO(2) was 58.9 +/- 12.4 (P <.001, cerebral vs somatic). During regional cerebral perfusion, cerebral rSO(2) was 80.7 +/- 8.6, and somatic rSO(2) was 41.4 +/- 7.1 (P <.001). Postbypass cerebral rSO(2) was 53.2 +/- 14.9, and somatic rSO(2) was 76.4 +/- 7.7 (P <.001). The risk of cerebral desaturation was significantly increased after cardiopulmonary bypass. CONCLUSIONS: Cerebral oxygenation was maintained during regional cerebral perfusion at prebypass levels with deep hypothermia. However, after rewarming and separation from cardiopulmonary bypass, cerebral oxygenation was lower compared with prebypass or somatic values. These results indicate that cerebrovascular resistance is increased after deep hypothermic cardiopulmonary bypass, even with continuous perfusion techniques, placing the cerebral circulation at risk postoperatively.

Analysis of Variance↗

PubMed2004

Alteration of the critical arteriovenous oxygen saturation relationship by sustained afterload reduction after the Norwood procedure.

OBJECTIVES: Hemodynamic vulnerability after the Norwood procedure for hypoplastic left heart syndrome results from impaired myocardial function, and critical inefficiency of parallel circulation. Traditional management strategies have attempted to optimize circulatory efficiency by using arterial oxygen saturation (SaO(2)) as an index of pulmonary/systemic flow balance, attempting to maintain SaO(2) within a theoretically optimal critical range of 75% to 80%. This optimal range of SaO(2) has not been verified clinically, and strategies targeting SaO(2) may be limited by the fact that SaO(2) is a poor predictor of systemic oxygen delivery. We have previously reported higher venous saturation (SvO(2)), lower arteriovenous oxygen content difference, lower systemic vascular resistance, lower pulmonary/systemic flow ratio, and improved survival with the perioperative use of phenoxybenzamine and continuous monitoring of SvO(2). In this investigation, we tested the hypothesis that intense afterload reduction with phenoxybenzamine would modify the SvO(2)-SaO(2) relationship by preventing deterioration of systemic oxygen delivery at high SaO(2). METHODS: Seventy-one consecutive neonates undergoing the Norwood procedure with and without phenoxybenzamine were studied. Perioperative hemodynamic management targeted SvO(2) greater than 50%. Hemodynamic data were prospectively acquired for 48 hours postoperatively and analyzed to assess the effect of phenoxybenzamine on the relationship between SaO(2) and SvO(2) and other hemodynamic indices. Sixty-two patients received phenoxybenzamine 0.25 mg/kg on cardiopulmonary bypass; 9 who did not served as controls. RESULTS: In control patients, SvO(2) peaked at an SaO(2) of 77%, with reduced SvO(2) at SaO(2) > 85% and SaO(2) < 70% (P <.01), while arteriovenous oxygen content difference increased with SaO(2) greater than 80% (P <.001). In patients receiving phenoxybenzamine, the SvO(2) increased linearly with SaO(2) greater than 65% (P <.001), and arteriovenous oxygen content difference was constant at all SaO(2) (P = ns). The SvO(2) was higher, and the arteriovenous oxygen content difference lower, across the whole SaO(2) range with phenoxybenzamine (P <.0001). CONCLUSIONS: A critical range of SaO(2) for optimizing systemic oxygen delivery was confirmed in control patients, and was effectively eliminated by phenoxybenzamine, specifically by eliminating the systemic hypoperfusion associated with high SaO(2). This effect allows higher SaO(2) to be included in a rational hemodynamic strategy to improve systemic oxygen delivery in the early postoperative management of patients receiving intense afterload reduction with phenoxybenzamine. The predictability of SvO(2) from SaO(2) is low in both groups, emphasizing the importance of SvO(2) measurement in these patients.

Arteries↗

PubMed2004

Single-ventricle physiology: perioperative implications.

Neonates with functional single ventricles have pulmonary and systemic circulations that are supplied in parallel, creating significant cyanosis and ventricular volume overload. The goal of palliative surgery, excluding transplantation, is to convert single-ventricle circulation from a parallel to a series arrangement. This will ultimately require a complete cavopulmonary anastomosis (Fontan-type procedure) in which vena caval blood is rerouted directly into the pulmonary circulation. Various factors require that this palliation occur in stages. Stage I surgery, which is often a Norwood procedure, is done in the neonatal period and stabilizes, but does not resolve, parallel circulation. The tenuous balance between pulmonary and systemic perfusion during this stage makes noncardiac surgery hazardous, and it should be restricted to urgent or emergent indications. Stage II surgery, or partial cavopulmonary anastomosis, relieves both parallel circulation and volume overload, but not cyanosis. Relatively stable hemodynamics during this stage create favorable conditions for elective surgery. Patients who have undergone stage III surgery, the Fontan-type repair, vary in age from toddlers to adults, and in physical status from well-compensated to significantly debilitated. Fontan patients require thorough preoperative assessment when elective surgery is contemplated. Optimal communication between surgeons, anesthesiologists, and cardiologists is essential when caring for the patient with single-ventricle physiology.

Adult↗