Continuous monitoring of jugular venous oxygen saturation in head-injured patients

Abstract

✓ The continuous measurement of jugular venous oxygen saturation (SjvO2) with a fiberoptic catheter is evaluated as a method of detecting cerebral ischemia after head injury. Forty-five patients admitted to the hospital in coma after severe head injury had continuous and simultaneous monitoring of SjvO2, intracranial pressure, arterial oxygen saturation, and end-tidal CO2. Cerebral blood flow, cerebral metabolic rates of oxygen and lactate, arterial and jugular venous blood gas levels, and hemoglobin concentration were measured every 8 hours for 1 to 11 days. Whenever SjvO2 dropped to less than 50%, a standardized protocol was followed to confirm the validity of the desaturation and to establish its cause. Correlation of SjvO2 values obtained by catheter and with direct measurement of O2 saturation by a co-oximeter on venous blood withdrawn through the catheter was excellent after in vivo calibration when there was adequate light intensity at the catheter tip (176 measurements: r = 0.87, p < 0.01). A total of 60 episodes of jugular venous oxygen desaturation occurred in 45 patients. In 20 patients the desaturation value was confirmed by the co-oximeter. There were 33 episodes of desaturation in these 20 patients, due to the following causes: intracranial hypertension in 12 episodes, hypocarbia in 10, arterial hypoxia in six, combinations of the above in three, systemic hypotension in one, and cerebral vasospasm in one. The incidence of jugular venous oxygen desaturations found in this study suggests that continuous monitoring of SjvO2 may be of clinical value in patients with head injury.

The influence of arterial oxygenation on cerebral venous oxygen saturation during hyperventilation

“…The observation that bead-injured patients with cerebral venous desaturation had a higher mortality than those without such episodes highlights the potential benefit of detecting and treating such desaturation. 16 It would appear that the most important factor controlling cerebral blood flow (CBF) is PaCO2, as shown by the higher SjvO2, PjvO2 and CjvO2 at the higher PaCO2 of 30 mmHg (P < 0.01). Nonetheless, in the 12 patients studied, hyperoxygenation was beneficial in reducing the incidence of cerebral venous oxygen desaturation during hyperventilation.…”

“…However, others have shown reductions in CBF with hyperoxia in normocapnic piglets, 13 ponies, 14 infants Is and adults. 16 This cerebral vasoconstriction may negate any potential beneficial effects of hyperoxia during hyperventilation. The effect of arterial hyperoxygenation on cerebral venous 0 2 content in anaesthetized patients during acute hyperventilation has not been fully investigated and is the purpose of this study.…”

Untitled

“…Several investigators using continuous jugular oxygen monitors have observed a significant association between episodes of jugular oxygen desaturation and poor outcome following head injury. [10,11,40,41,46] For example, Robertson, et al, [41] observed a 21% mortality rate in patients with no desaturation, 37% after a single episode, and 69% after multiple episodes. Poor outcome may also be associated with a reduced AVDO 2 , [21,40] because cerebral metabolism is significantly depressed once cerebral infarction has occurred.…”

“…Although interpretation of SjVO 2 is based on several assumptions, a good correlation between SjVO 2 measured fiberoptically and via catheter has been observed. [46] Unfortunately, jugular saturation monitors require frequent recalibration and a high percentage of readings are erroneous because of catheter movement, displacement, intimal impaction, or clot formation. [14,46] Despite these limitations, jugular saturation monitoring can help guide therapy, optimize CPP, and measure the effects of therapeutic interventions, such as ventilation or mannitol administration, to ensure adequate CBF to meet metabolic demands.…”

The effects of hypoxaemia and recommendations for postoperative oxygen therapy

“…Traditionally, electrophysiological monitoring [36] and measurement of oxygen saturation and lactate levels in jugular venous blood [37,38] have been used to monitor the adequacy of cerebral oxygen delivery; more recent studies have used the noninvasive technique of near-infrared spectroscopy of the brain [39].…”