Jugular Venous Oxygen Tension Research Articles

Comparison of different methods to calculate venous admixture in anaesthetized horses

ObjectiveThe aim of this study was to compare different methods to determine venous admixture (Q˙s/Q˙t) in anaesthetized horses. The first objective was to estimate Q˙s/Q˙t using jugular venous blood oxygen content (Q˙s/Q˙t jugular), and a fixed value for the oxygen extraction (F-shunt). The second objective was to assess the influence of blood pressure and positioning on oxygen extraction. The third objective was to perform regression analysis between jugular and mixed venous blood oxygen tensions. Study designProspective, experimental trial. AnimalsThe study was performed with seven warmblood horses that were anaesthetized with detomidine, butorphanol, ketamine, diazepam and isoflurane in oxygen. MethodsMultiple simultaneous arterial, jugular venous and pulmonary arterial blood samples were taken under normotensive and hypotensive conditions in lateral and dorsal recumbency. Arterial, mixed venous, and end-capillary oxygen content were calculated. ResultsA significant correlation between Q˙s/Q˙t and Q˙s/Q˙t jugular was found [intraclass correlation coefficient (ICC) = 0.68, p < 0.001], and Bland–Altman analysis showed a bias of –11.5% and wide limits of agreement (–27.7% to 4.6%). F-shunt significantly correlated with Q˙s/Q˙t (ICC = 0.88, p < 0.001), and Bland–Altman analysis showed a lower bias (–1.97) and narrower limits of agreement (–13.8% to 9.9%). Positioning and blood pressure significantly influenced oxygen extraction. The regression formula was Y = 0.80X + 2.61 (where Y is the calculated mixed venous oxygen tension and X is the jugular venous oxygen tension) when outliers were excluded (ICC=0.82, p < 0.001). Conclusions and clinical relevanceThis study shows that F-shunt provides reasonable estimates of Q˙s/Q˙t but can possibly be improved by using simple algorithms without the need for pulmonary arterial catheterization. These algorithms use blood pressure- and positioning-dependent oxygen extraction and regression analysis between jugular venous and pulmonary arterial oxygen tension. Although promising, the validity of these algorithms needs to be determined in future studies.

Monitoring the effects of propofol and sevoflurane on cerebral oxygen supply-demand balance using transcranial Doppler sonography and jugular bulb saturation in pediatric open heart surgery

Background Increasing awareness of neurologic abnormalities associated with congenital heart surgical intervention has heightened investigations for prevention of neurologic injury during the perioperative period. This study investigated the effects of propofol and sevoflurane on cerebral oxygen supply demand balance using transcranial Doppler sonography and jugular bulb saturation in pediatric open heart surgery. Methods After obtaining institutional approval and a written consent from parents, 60 children who were admitted for elective open cardiac surgery for correction of congenital heart disease using CPB were included in this study. Children were randomized into two groups; group (P) and group (S). Induction of Anesthesia was achieved by 5 μg/Kg I.V. fentanyl, propofol 2- 2.5 mg/Kg (in propofol or P group) or sevoflurane 2-3 MAC (in sevoflurane or S group). Anesthesia was maintained by propofol infusion between 75-100 μg/kg/min in P group or sevoflurane 2 MAC in S group. Calculated parameters from the blood gas variables included cerebral metabolic rate of oxygen (CMRO 2 ), cerebral extraction of oxygen (CeO 2 ) and cerebral blood flow equivalent (CBF). Arterial blood gases (ABG) and velocities of flow were monitored by Trancranial Doppler at 5 time points : before the surgery, before CPB, during CPB (after establishment of full flow), after CPB and after recovery. Neurological examination and CT scan were done before surgery and 2 days after that. Results There is no significant difference between the two groups in demographic data. Children in propofol group showed lower heart rate values after induction and after CPB than those in sevoflurane group. Mean arterial pressure was statistically higher in sevoflurane group compared with propofol group after induction. Children in sevoflurane group showed significantly higher; velocity maximum, velocity mean and pulsatile index, in the after induction and after bypass periods than those in propofol group. Velocity minimum showed no difference between the two groups. SjvO 2 , CMRO 2 , CeO 2 and CBF was significantly different after induction in sevoflurane group compared with propofol group. Perioperative blood gases showed no difference between the studied groups. Conclusion Compared with propofol anesthesia, sevoflurane anesthesia provides a wider margin of safety against impaired cerebral oxygenation and better preservation of systemic hemodynamics. Moreover, cerebral oxygen saturation may not reflect changes in cerebral oxygenation as monitored by jugular venous oxygen tension measurement in children undergoing CPB.

Regional oxygenation and systemic inflammatory response during cardiopulmonary bypass: Influence of temperature and blood flow variations

Objective: To evaluate the role of target temperature (28° or 34°C) in cardiac surgery on regional oxygenation during hypothermia and rewarming and systemic inflammatory response. Design: Prospective, controlled, and randomized clinical study. Setting: University hospital. Participants: Elderly patients (mean age 70 ± 2 years) with acquired heart disease with an anticipated bypass time exceeding 120 minutes (n = 30). Interventions: The patients were cooled to either 28°C (n = 15) or 34°C (n = 15). At hypothermia, bypass blood flow was reduced twice from full flow (2.4 L/min/m2 body surface area [BSA]) to 2.0 L/min/m2. Measurements and Main Results: Hepatic and jugular venous oxygen tension and saturation were higher at 28°C than at 34°C. In comparison with the preoperative values, at 28°C hepatic venous values were higher; whereas at 34°C, they were lower. The reduction of pump blood flow during hypothermia, from 2.4 to 2.0 L/min/m2was accompanied by reductions of central, jugular, and hepatic oxygenation at both target temperatures. During rewarming, central and regional venous oxygenation decreased irrespective of the preceding temperature. The decrease was most pronounced in hepatic venous blood, with the lowest individual values <10%. Serum concentrations of C3a and IL-6 increased during hypothermia and increased further during rewarming irrespective of the preceding temperature. Conclusion: During cardiopulmonary bypass, hypothermia at 28°C increases regional and central venous oxygenation better than at 34°C. In contrast, venous oxygenation decreases during rewarming irrespective of the preceding temperature. No significant difference in the systemic inflammatory response associated with target temperature was detected. © 2003 Elsevier Inc. All rights reserved.

Effect of endotracheal suctioning on cerebral oxygenation in traumatic brain-injured patients.

In patients with severe head injuries, brain damage occurs not only from the primary trauma but also secondarily from a reduction in cerebral oxygenation as a result of brain swelling, ischemia, and elevated intracranial pressure (ICP). However, routine interventions designed to maintain oxygenation, such as endotracheal suctioning (ETS), also may negatively affect the cerebrovascular status by increasing the ICP. The purpose of this study was to determine whether ETS influences cerebral oxygenation in patients with traumatic brain injury. Descriptive, prospective, with repeated assessments within each patient. Ten-bed trauma intensive care unit in a university Level I trauma center. Nineteen patients who were 16 yrs or older, had acute head injury, a Glasgow Coma Scale score < or =8; external ventricular drain and arterial pressure devices in place, and were intubated and mechanically ventilated. ETS protocol consisting of administration of four ventilator-delivered breaths at 135% of the patients' actual tidal volume, 100% F(IO)2, before and after suctioning with a standardized catheter at a 16-L flow rate. This study examined cerebrovascular responses as measured by the traditional measures of ICP and cerebral perfusion pressure, as well as middle cerebral artery velocity and jugular venous oxygen tension that occurred during ETS in head-injured adults. The results of this study show that both ICP and cerebral perfusion pressure are increased during ETS. In the majority of patients (84%), the ICP returned to baseline values within 2 mins. The increase in jugular venous oxygen tension associated with increases in middle cerebral artery velocity and mean arterial pressure suggests that cerebral oxygen delivery was maintained during ETS. Cerebral changes associated with ETS using the described protocol are consistent with the preservation of cerebral oxygenation.

Evaluation of the Calcium Channel‐Blocking Agents Diltiazem and Verapamil for Treatment of Feline Hypertrophic Cardiomyopathy

To determine the efficacy of and clinical response to several pharmacologic agents for treatment of idiopathic hypertrophic cardiomyopathy in cats, 17 symptomatic cats were randomized to treatment with either propranolol, diltiazem, or verapamil. Clinical, laboratory, radiographic, electrocardiographic, and echocardiographic data were obtained before treatment and after 3 and 6 months of chronic oral therapy. Too few of the cats receiving propranolol or verapamil survived long enough to obtain long-term data needed to make statistical comparisons between groups. However, all 12 cats ultimately treated with diltiazem became asymptomatic, and no adverse effects from this drug were noted in any of these cats. Treatment with diltiazem was associated with a significant reduction of pulmonary congestion assessed radiographically (P less than 0.01), and improved ventricular filling based on echocardiographic measurements of left atrial size (P less than 0.05), left ventricular internal diastolic dimension (P less than 0.05), and relaxation time index (P less than 0.001). There was also a drug-related improvement in jugular venous oxygen tension (P less than 0.001) and blood lactate concentration (P less than 0.01) suggesting improved peripheral perfusion in the cats receiving diltiazem. The results indicate that diltiazem provides an effective and apparently safe treatment for the management of feline hypertrophic cardiomyopathy.

Continuous conjunctival oxygen tension (PcjO2) monitoring for assessment of cerebral oxygenation and metabolism during carotid artery surgery.

The clinical value of noninvasive continuous monitoring of conjunctival oxygen tension for assessment of cerebral perfusion during carotid endarterectomy performed under general anaesthesia has been evaluated. The patients (n = 17; mean age 62.5 +/- 1.7 years) were monitored as follows: conjunctival oxygen tension (PcjO2); internal jugular venous oxygen tension at the skull base level (PcijvO2); arterial blood pressure; arterial and internal jugular venous blood gases; acid-base data and lactate, pyruvate levels; end-tidal CO2 concentration. The mean preanaesthetic PcjO2 level of 4.86 +/- 0.40 kPa was significantly lower than PaO2(PcjO2)/PaO2 ratio of 0.48). Following anaesthesia, a larger PcjO2-PaO2 gradient (ratio 0.32) was seen in spite of the hyperoxic situation (FiO2 = 0.40) due to vasoconstriction induced by slight hypocapnia (reduction of PaCO2 from 5.13 +/- 0.08 to 4.64 +/- 0.10 kPa). The carotid artery crossclamping resulted in a rapid and pronounced decrease of PcjO2, while PcijvO2 remained unchanged. No relationship between PcjO2 and stump pressure was found, while a significant correlation (P less than 0.02) between PcjO2 and lactate in effluent venous blood from the brain was demonstrable. It is concluded that PcjO2 monitoring seems a clinically useful trend indicator of cerebral perfusion in the individual patient. Due to large interindividual variations in basal PcjO2 readings and in PcjO2 changes during carotid artery clamping, however, transconjunctival oxygen tension monitoring does not seem to allow early and accurate recognition of impending cerebral ischaemia during carotid endarterectomy, and its routine use therefore seems of limited value.

Controlled hypotension with sodium nitroprusside: effects on cerebral blood flow and cerebral venous blood gases in patients operated for cerebral aneurysms.

The effect on cerebral haemodynamics of arterial hypotension induced by sodium nitroprusside infusion was studied in nine patients at the end of operations for intracranial aneurysms under N2O-O2-halothane anaesthesia. Cerebral blood flow (CBF), using the intraarterial 133Xe injection method, and cerebral jugular venous blood gases were monitored before, during and after the induced hypotension. CBF and jugular venous oxygen tension (PvO2) remained constant during the hypotensive period. Following its termination, a 13% increase in CBF occurred (P less than 0.05) and PvO2 showed the same trend, a 5% increase (P less than 0.30). Regional CBF recordings (rCBF) in 16 small areas within the cerebral hemisphere were obtained at each measurement. In four of the patients, rCBF abnormalities were present in the form of hyperaemic regions, probably induced by the operation or the disease itself. The focal abnormalities were not accentuated during hypotension nor were ischaemic regions disclosed. It is concluded that sodium nitroprusside has only a minor influence on cerebral haemodynamics in the anaesthetized state.

Cerebral blood flow and metabolism in man following cardiac arrest.

We measured cerebral oxygen extraction, cerebral blood flow(CBF), and cerebral metabolic rate (CMRO2) in comatose patients during the first 60 hours after resuscitation from cardiac arrest. Each patient was studied 2 or 3 times. CBF was determined by a modification of the Kety-Schmidt method using inhaled Xenon133. Over the study period jugular venous oxygen tension and saturation rose, while the oxygen content difference between arterial and jugular venous blood fell, indicating a progressive increase in the ratio of CBF to metabolism CBF and CMRO2 measurements confirmed this. Between 2 and 6 hours after resuscitation both measurements were severely but proportionately depressed to less than 50% of normal. After 6 hours CBF was increased disproportionately to CMRO2 so that a relative hyperemia developed and persisted for the duration of the study. Although regional inhomogeneity of flow and regional ischemia cannot be ruled out, we have found no evidence for global cerebral ischemia between 2 and 60 hours post-resuscitation as an explanation for failure of recovery. In man following cardiac arrest restoration of levels of global cerebral blood flow, which can be considered adequate relative to the depressed metabolic state of the tissue, is achieved within 2 hours of resuscitation.

CEREBRAL RESPONSES TO THE ADDITION OF NITROUS OXIDE TO HALOTHANE IN MAN

Cerebral responses to the substitution of 60% nitrous oxide for nitrogen during halothane anaesthesia (0.84%, end-tidal) were studied in four patients during surgery. The mean (+/-SEM) cerebral blood flow equivalent and internal jugular venous oxygen tension during halothane anaesthesia, 17+/-3 ml blood/ml oxygen and 41+/-2 mm Hg respectively, increased significantly to 45+/-3 ml blood/ml oxygen and 54+/-3 mm Hg following the introduction of nitrous oxide. On the withdrawal of nitrous oxide, the mean cerebral blood flow equivalent and internal jugular venous oxygen tension returned gradually to the control values. Cerebral perfusion pressure and blood-gas values, other than the internal jugular venous oxygen tension, did not change significantly. Marked slowing of the e.e.g. was observed following the addition of nitrous oxide to halothane, Upon the withdrawal of nitrous oxide the e.e.g. returned to the control pattern. These results indicate that cerebral blood flow was in excess of oxygen demand during nitrous oxide/halothane anesthesia in man.

CEREBRAL BLOOD FLOW AND METABOLISM DURING HYPOTENSION INDUCED WITH SODIUM NITROPRUSSIDE

Cerebral blood flow and metabolism have been studied during hypotension induced with sodium nitroprusside in 20 patients undergoing surgery for cerebral aneurysms. Cerebral blood flow was measured using an injection of xenon-133 into the common carotid artery, after the retrograde cannulation of the superficial temporal artery, and exponential stripping of the decay curve as detected by a scintillation counter placed over the ipsilateral fronto-parietal region. In the group as a whole there was no significant decrease in cerebral blood flow, as determined by measurement of grey matter flow, or change in the cerebral metabolic rate for oxygen when the blood pressure was reduced by 42%. Cerebrovascular resistance decreased by 40%. During hypotension there were significant decreases in arterial oxygen tension, arterial and jugular venous oxygen contents, but insignificant decreases in jugular venous oxygen tension and arterio-jugular venous oxygen content difference. There were no complications that could be attributed to sodium nitroprusside.

A CLINICAL APPRAISAL OF THE ADEQUACY OF BRAIN CIRCULATION DURING ANAESTHESIA (WITH PARTICULAR REFERENCE TO CAROTID THROMBOENDARTERECTOMY)

Studies in 30 patients (out of 100) having carotid thromboendarterectomy are described. 1. The validity of using internal jugular venous oxygen tension (Pvo2) as a measure of cerebral blood flow (cbf) in these clinical situations was tested in 30 anaesthetized patients from whom 90 paired values of arterial carbon dioxide tensions (Paco2) and Pvo2 were obtained during carotid thromboendarterectomy. A significant relationship, Pvo2 = 1.21 Paco2 + 1.2, was obtained over a wide range of Pao2 and Paco2 values, indicating that Pvo2 was a reliable measure of cbf under these circumstances. Since cbf has a linear relationship with Paco2, and Pvo2 is similarly related to Paco2, it follows that cbf is also related to Pvo2. The physiological basis and validity of this relationship (Fick principle) is outlined. No significant differences were found to result from three types of anaesthetic agents used: cyclopropane, nitrous oxide and halothane, and halothane and oxygen. This indicated that any of these three agents provided adequate cbf under the clinical circumstances described in this study. There were no differences in samples obtained during the use of a temporary internal carotid artery shunt. This indicated that the shunt provided blood flow sufficient to maintain cerebral circulation. 2. Although the anaesthetic agent per se did not appear important, it appeared essential that the conduct of anaesthesia with the agent provide stability. Monitoring of the electrocardiogram, central venous pressure, and arterial blood pressure provided a ready assessment of cardiovascular stability. Ophthalmodynamometry provided a useful means of accurately assessing the patency of the carotid circulation in the early postoperative period following thromboendarterectomy by comparison with the preoperative retinal artery diastolic pressure. It proved too cumbersome a technique to be of value during the surgical procedure. CNS stability was maintained by attention to “light” adequate general anaesthesia, near-normal body temperature, and adequate systemic arterial blood gas Po2, Pco2, pH, and acid-base balance (with emphasis on the prevention of hypocarbia and tendency towards hypercarbia). Continuous eeg monitoring had limited usefulness as an index of this stability and in assessing adequacy of cbf. Because our surgical shunting procedure was effective in all patients studied, as indicated by the stability of our Pvo2 values during the shunt period, the eeg was also of limited value as a diagnostic index of cerebral ischaemia or a prognostic influence on the ultimate course of the patient postoperatively.

Internal jugular venous oxygen tension as an index of cerebral blood flow during carotid endarterectomy.

From published data which related cerebral blood flow (CBF) to arterial carbon dioxide tension (Pa co co2 ) and related CBF to internal jugular venous oxygen tension (Pv o o2 ), the relationship Pv o o2 =1.20 Pa co co2 -4.9 was derived. This relationship was based on the documented changes in CBF induced by alterations in Pa co co2 in normal man anesthetized with halothane. The validity of using Pv o o2 as a measure of CBF in clinical situations was tested in 29 anesthetized patients from whom 90 paired values of Pa co co2 and Pv o o2 were obtained during reconstructive carotid artery surgery. A significant relationship, Pv o o2 =1.08 Pa co co2 +3.6 was obtained over a wide range of Pa co co2 values, indicating that Pv o o2 was a reliable measure of CBF under these circumstances. No significant differences were found to result from the various anesthetic agents used, the age of patients, and the period of sampling. Samples obtained during the use of a temporary internal carotid artery shunt indicate that the shunt provides blood flow sufficient to maintain cerebral circulation normally responsive to hypercarbia.