Mark G. Goetting

Noninvasive cerebral optical spectroscopy for monitoring cerebral oxygen delivery and hemodynamics.

ObjectiveTo present an algorithm for noninvasive measurement of cerebral oxygen saturation (cerebral oximetry) and cerebral hemodynamics with near infrared spectroscopy. DesignIn vitro correlation of oximetry measurements with reference measurements; illustrative cases of hemodynamic and oximetric recordings. SettingTertiary care neuroscience ICU. PatientsBrain-injured patients with a prolonged, decreased level of consciousness chosen as illustrative examples. InterventionsTwo-channel multiple wavelength diffuse infrared transmission spectroscopy was interfaced with the scalp using adhesive. Transmission data were collected with gross superficial-to-deep spatial resolution. Saturation calculation based on the deep signal was observed longitudinally in the patient. With the same technology, arterial input and cerebral response functions, generated by iv tracer bolus, were deconvoluted to measure mean cerebral transit time. Measurements and Main ResultsA positive linear regression fit between diffuse transmission oximetry and measured blood oxygen saturation over the range 23% to 99% (r2 = .98, p < .001) was noted. ConclusionThe approach used overcomes previously identified difficulties with cerebral oximetry, and demonstrates excellent in vitro correlation. The technique can be performed clinically without difficulty. A simultaneous measure of mean cortical transit time is possible. (Crit Care Med 1991; 19:89)

The clinical implications of continuous central venous oxygen saturation during human CPR

Study objective: The purpose of this study was to observe, measure, and describe the changes in central venous oxygen saturation during CPR and immediately after return of spontaneous circulation. It also was to examine the clinical utility of continuous central venous oxygen saturation monitoring as a indicator of return of spontaneous circulation during CPR in human beings. Design and setting: Eight-month, prospective, non-outcome, observational, nonrandomized case series in the ED of a large urban hospital. Types of patients: Adult normothermic, nontraumatic, out-of-hospital cardiopulmonary arrests. Interventions: All patients were managed according to advanced cardiac life support guidelines. A proximal aortic and double-lumen central venous catheter was placed. Central venous oxygen saturation was measured continuously spectrophotometrically with a fiberoptic catheter in the central venous location. Measurements: Aortic blood pressure and central venous oxygen saturation were simultaneously measured throughout each resuscitation. Return of spontaneous circulation was defined as a systolic blood pressure of more than 60 mm Hg for more than five minutes. Results: One hundred patients who experienced 68 episodes of cardiac arrest were studied. Patients with return of spontaneous circulation had a higher initial and statistically higher mean and maximal central venous oxygen saturation than those without return of spontaneous circulation ( P = .23, .0001, and .0001, respectively; P Conclusion: Continuous central venous oxygen saturation monitoring can serve as a reliable indicator of return of spontaneous circulation during CPR in human beings.

High atrial natriuretic peptide concentrations blunt the pressor response during cardiopulmonary resuscitation in humans

ObjectiveTo determine the relationship of circulating atrial natriuretic peptide concentrations to the pressor response to high-dose epinephrine in patients undergoing cardiopulmonary resuscitation (CPR) for cardiac arrest. DesignProspective study. PatientsFourteen normothermic, adult, prehospital and emergency department patients suffering unexpected cardiac arrest. InterventionPatients received high-dose epinephrine (0.2 mg/kg) iv when standard advanced cardiac life support (including multiple 1-mg dosages of epinephrine) failed to result in return of spontaneous circulation. Measurements and Main ResultsCardiac arrest patients were separated into those patients with and without detectable serum atrial natriuretic peptide concentrations, and were termed the “low atrial natriuretic peptide” and “high atrial natriuretic peptide” groups, respectively. Their aortic pressure response to high-dose (0.02 mg/kg) epinephrine was compared. The proportion with positive assays was compared with a group of healthy control subjects.Fourteen patients were studied. Eight patients had low serum atrial natriuretic peptide concentrations and six patients had high circulating atrial natriuretic peptide concentrations. The mean concentration in the high atrial natriuretic peptide group was 151 ± 82 pg/mL. The proportion with positive assays (six of 14 patients) was greater than in the group in spontaneous circulation (three of 29 patients) (p = .002). The maximal increase in the aortic relaxation-phase pressures after high-dose epinephrine was 9 ± 7 torr (1.2 ± 0.9 kPa) in the low atrial natriuretic peptide group and 0 ± 5 torr (0 ± 0.7 kPa) in the high atrial natriuretic peptide group (p = .03). The maximal increase in the aortic compression pressures after high-dose epinephrine was 17 ± 13 torr (2.3 ± 1.7 kPa) in the low atrial natriuretic peptide group and 2 ± 10 torr (0.3 ± 1.3 kPa) in the high atrial natriuretic peptide group (p = .03). Thus, pressor responses after high-dose epinephrine administration were observed in patients in the low atrial natriuretic peptide group, but this response was absent in patients in the high atrial natriuretic peptide group. ConclusionsCardiac arrest patients receiving CPR have higher circulating atrial natriuretic peptide concentrations than healthy subjects. High serum atrial natriuretic peptide concentrations may antagonize the vasopressor response to epinephrine. Blocking this effect of atrial natriuretic peptide may improve outcomes in patients suffering cardiac arrest. (Crit Care Med 1994; 22:213–218)

The Clinical Implications of Continuous Central Venous Oxygen Saturation During Human CPR

STUDY OBJECTIVE The purpose of this study was to observe, measure, and describe the changes in central venous oxygen saturation during CPR and immediately after return of spontaneous circulation. It also was to examine the clinical utility of continuous central venous oxygen saturation monitoring as a indicator of return of spontaneous circulation during CPR in human beings. DESIGN AND SETTING Eight-month, prospective, non-outcome, observational, nonrandomized case series in the ED of a large urban hospital. TYPES OF PATIENTS: Adult normothermic, nontraumatic, out-of-hospital cardiopulmonary arrests. INTERVENTIONS All patients were managed according to advanced cardiac life support guidelines. A proximal aortic and double-lumen central venous catheter was placed. Central venous oxygen saturation was measured continuously spectrophotometrically with a fiberoptic catheter in the central venous location. MEASUREMENTS Aortic blood pressure and central venous oxygen saturation were simultaneously measured throughout each resuscitation. Return of spontaneous circulation was defined as a systolic blood pressure of more than 60 mm Hg for more than five minutes. RESULTS One hundred patients who experienced 68 episodes of cardiac arrest were studied. Patients with return of spontaneous circulation had a higher initial and statistically higher mean and maximal central venous oxygen saturation than those without return of spontaneous circulation (P = .23, .0001, and .0001, respectively; P less than .05 is significant). No patient attained return of spontaneous circulation without reaching a central venous oxygen saturation of at least 30%. Only one of 68 episodes of return of spontaneous circulation was attained without reaching a central venous oxygen saturation of at least 40%. A central venous oxygen saturation of greater than 72% was 100% predictive of return of spontaneous circulation. CONCLUSION Continuous central venous oxygen saturation monitoring can serve as a reliable indicator of return of spontaneous circulation during CPR in human beings.