Usefulness of Simultaneous Measurement of Brain and Muscle rSO2 (Regional Oxygen Saturation) in Shock Patients: a Report of Three Cases

doi:10.21203/rs.3.rs-570750/v1

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Usefulness of Simultaneous Measurement of Brain and Muscle rSO₂ (Regional Oxygen Saturation) in Shock Patients: a Report of Three Cases

https://doi.org/10.21203/rs.3.rs-570750/v1

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Background

In the field of emergency medical care, we often experience a situation in which we cannot measure pulse oximetric saturation (SpO₂) or blood pressure due to circulatory failure associated with shock. However, as we can measure rSO₂ values of the brain even in patients with shock, we hypothesized that we could evaluate the oxygen supply-demand balance between brain and muscle tissue by simultaneously measuring regional oxygen saturation (rSO₂) values of the brain and muscle tissue of patients with shock.

Case presentation

We attached a TOS-OR rSO₂ monitor (TOSTEC CO., Tokyo, Japan) to 10 healthy volunteers and measured the rSO₂ values of their brain and muscle for 3 minutes. The rSO₂ values of their brain cerebral regional oxygen saturation (crSO₂) and muscle regional oxygen saturation (mrSO₂) were 77.6±1.6% and 76.2±1.3% (mean ± SD). There was little difference between crSO₂ and mrSO₂ (cerebro-musculoskeletal difference in regional saturation of oxygen; c-mDrSO₂). However, there were discernible amount of c-mDrSO₂ in three cases with shock, Case 1 showed a prolonged shock state due to septic shock caused by bacterial pneumonia. Her crSO₂ values was always higher than her mrSO₂ value, and there was a c-mDrSO₂. Case 2 showed a decrease in mean arterial pressure (MAP) with the development of septic shock caused by intestinal perforation. His crSO₂ value was higher than that of his mrSO₂, and c-mDrSO₂ increased with the decrease of his MAP. Case 3 had a low MAP due to hemorrhagic shock caused by postpartum hemorrhage. Her crSO₂ value was higher than that of her mrSO₂ and a c-mDrSO₂ was present. After resuscitation, the c-mDrSO₂ decreased with the increase in her blood pressure.

Conclusion

We evaluated the usefulness of simultaneous measurement of crSO₂ and mrSO₂ as an objective and non-invasive method in shock management. Even if SpO₂ or blood pressure could not be measured due to circulatory failure associated with shock, it was possible to measure the values of crSO₂ and mrSO₂, which changed in real time with fluctuation of the blood pressure. Unlike previous monitoring devices, the rSO₂ monitor may continuously and clearly reflect the changes in local oxygen supply-demand balance.

Critical Care & Emergency Medicine

Near-infrared spectroscopy

shock

rSO2 monitor

muscle rSO2

brain rSO2

In the field of emergency medical care, we often experience a situation in which we cannnot measure pulse oximetric saturation (SpO₂) or blood pressure due to circulatory failure associated with shock. Regional oxygen saturation (rSO₂) is known as an indicator of changes in the local oxygen supply-demand balance [1]. Particularly, near-infrared spectroscopy which measures rSO₂ in the brain can noninvasively measure the proportion of oxygenated hemoglobin at the site to be monitored in real-time using the difference in the absorption of near-infrared rays from oxygenated hemoglobin and reduced hemoglobin in the blood [2]. This method can measure oxygen saturation in a non-pulsatile flow environment and therefore can be used in patients with circulatory failure [3] or after cardiac arrest [4]. To our knowledge, however, no previous study has simultaneously evaluated the oxygen supply-demand balance between central such as the brain and peripheral such as the muscle tissue in a noninvasive and real-time manner in patients with shock.

We hypothesized that we could evaluate the oxygen supply-demand balance between brain and muscle tissue by simultaneously measuring rSO₂ values of the brain and muscle tissues of patients in shock using an rSO₂ monitor (TOS-OR; TOSTEC CO., Tokyo Japan) [5, 6]. The study protocol was approved by the Institutional Review Board of Osaka University (approval no. 19540), which waived the need to obtain patient written informed consent because this was a noninvasive observational study.

Here, we show the rSO₂ values of the brain and muscle tissues of healthy volunteers and of three patients in shock in whom we preliminarily evaluated the rSO₂ values of the brain and muscle tissues during their resuscitation. We discuss the potential effectiveness of simultaneously assessing brain and muscle rSO₂ in shock management.

Brain and muscle rSO₂ in healthy volunteers

We attached the sensors of the rSO₂ monitor to the forehead and the dorsal lower leg of 10 healthy volunteers lying in the supine position and measured rSO₂ values at these locations for 3 minutes (Fig. 1). The reason for choosing the dorsal lower leg as the measurement site was because it was easy to attach the sensor when clothes are worn and measurement was less affected by body hair or physical constitution. When the sensor of the rSO₂ monitor was placed on the dorsal side of the lower leg, we confirmed by ultrasound that the depth from the skin surface to the muscle being measured by the sensor was 20 to 25 mm. The rSO₂ values of the volunteers’ brain (cerebral regional oxygen saturation [crSO₂]) and muscle (muscle regional oxygen saturation [mrSO₂]) measurements were 77.6 ± 1.6% and 76.2 ± 1.3% (mean ± SD), respectively. There was little difference in cerebro-muscular regional saturation of oxygen (c-mDrSO₂) as indicated by the small difference between the crSO₂ and mrSO₂ values (Table 1).

Table 1

Values of cerebral regional oxygen saturation (crSO₂) and muscle regional oxygen saturation (mrSO₂) in healthy volunteers
Patient No.	Age (years)	Sex	sBP (mmHg)	dBP (mmHg)	MAP (mmHg)	crSO₂ (%)		mrSO₂ (%)
						mean	SD	mean	SD
1	29	M	121	84	96	78.6	0.3	74.5	0.3
2	28	M	150	100	117	81.3	0.5	76.2	0.5
3	43	M	156	115	129	79.2	0.4	76.9	0.4
4	29	M	109	63	78	76.3	1.2	76.3	1.3
5	39	M	124	80	95	77.7	0.8	76.9	0.7
6	33	F	109	75	86	77.9	0.7	77.0	0.7
7	32	F	107	71	83	75.1	0.4	77.1	0.4
8	29	M	102	70	81	77.2	0.8	78.1	1.1
9	34	M	153	82	106	77.0	0.9	73.4	1.0
10	32	M	117	74	88	77.0	0.3	75.3	0.2
No. number, M male, F female, sBP systolic blood pressure, dBP diastolic blood pressure, MAP mean arterial pressure, SD standard deviation

Shock case 1

A 56-year-old woman was admitted to our hospital with respiratory distress and malaise. On arrival, her heart rate was 145 beats per minute, and we then could not palpate her radial artery pulse or measure SpO₂ because of her low blood pressure. We attached the sensors of the rSO₂ monitor to her forehead and dorsal lower leg and measured the rSO₂ values of her brain and muscle. Both values could be measured, and the value of crSO₂ was higher than that of mrSO₂. We diagnosed her condition as septic shock caused by bacterial pneumonia and treated her with fluid resuscitation immediately. Her mean arterial pressure (MAP) continued to be low, but after 1 hour we could measure a blood pressure by a noninvasive method. Meanwhile, the value of her crSO₂ remained higher than that of her mrSO₂. Although this patient’s shock state was prolonged by septic shock caused by bacterial pneumonia, the value of her crSO₂ was always higher than that of mrSO₂, and the c-mDrSO₂ was large (Fig. 2a).

Shock case 2

An 82-year-old man was transferred to our hospital with a diagnosis of septic shock caused by intestinal perforation. On admission, his blood pressure was 136/52 mmHg (MAP 73 mmHg), and his heart rate was 136 beats per minute under administration of noradrenaline and lactated ringers solution We urgently performed partial resection of the intestine on the day of transfer. Just after the operation, his MAP was over 65 mmHg with the administration of noradrenaline, and his crSO₂ value was about the same as his mrSO₂ value. However, his MAP gradually decreased to below 60 mmHg at 1.6 hours after the operation. Meanwhile, his crSO₂ value remained higher than that of his mrSO₂ value, and c-mDrSO₂ increased with the decrease of the MAP. His MAP did not decrease any further by 1.8 hours after the operation, and the c-mDrSO₂ stabilized. This patient showed a decrease in his MAP with the development of septic shock caused by intestinal perforation. His crSO₂ value remained higher than that of his mrSO₂, and the c-mDrSO₂ increased in tandem with the decrease of his MAP (Fig. 2b).

Shock case 3

A 38-year-old woman was transferred to our hospital with a diagnosis of hemorrhagic shock following postpartum hemorrhage. On admission, her blood pressure was 74/40 mmHg (MAP 38 mmHg), and her heart rate was 86 beats per minute We attached the TOS-OR rSO₂ sensor to her forehead and dorsal upper arm on admission and measured the values of crSO₂ and mrSO₂. The crSO₂ value was higher than that of her mrSO₂ value, and there was a c-mDrSO₂. The bleeding from her uterus persisted, and her hemoglobin on admission was 6.5 g/dL. We began the administration of red blood cells at admission and her MAP gradually increased. When her MAP rose above 85 mmHg, her crSO₂ value became about the same as that of her mrSO₂. In this patient with a low MAP due to hemorrhagic shock following postpartum hemorrhage, the value of her crSO₂ was higher than that of her mrSO₂ and a c-mDrSO₂ was present. After her blood pressure began to increase, the c-mDrSO₂ became much smaller (Fig. 2c).

We revealed the following three points by simultaneously measuring the values of crSO₂ and mrSO₂. First, the value of crSO₂ is almost the same as that of mrSO₂ in healthy volunteers. Second, even if SpO₂ or blood pressure cannot be measured due to circulatory failure associated with shock, it is possible to measure crSO₂ and mrSO₂. Third, in the shock state, there is a difference in rSO₂ values between brain and muscle, and the value of crSO₂ is higher than that of mrSO₂. The present study is the first report, to our knowledge, to suggest that measurement of crSO₂ and mrSO₂ in shock patients may continuously and clearly reflect the oxygen supply-demand balance.

There are three stages of shock: stage I (compensatory shock), stage II (decompensatory shock), and stage III (irreversible shock). Particularly, in the early phase of stage I, blood flow to the organs decreases, but blood flow in the major organs manages to be maintained by the physiological response generated to recover blood circulation [7]. Previous studies assessed blood flow to the organs in shock patients by placement of an intravascular catheter [8] or by pulse-wave Doppler [9, 10]. In contrast, we used the rSO₂ monitor as the tool to measure organ blood flow continuously and noninvasively.

Among the studies of patients in shock, there are reports that the value of crSO₂ is low when the MAP is low but that it increases with the increase in MAP [3, 11–13]. Other reports on mrSO₂ showed a similar tendency to that of crSO₂ [14–16].

In this first report of the simultaneous measurement and assessment of the values of crSO₂ and mrSO₂ in shock patients, we illustrated Fig. 2d the expected change of crSO₂ and mrSO₂ as the MAP changes. In the case of a stable MAP, the values of crSO₂ and mrSO₂ are almost equal, and the c-mDrSO₂ is small (C). In the case of decreased MAP, tissue blood flow to the non-major organs decreases, and the value of mrSO₂ also decreases (B). For this reason, the value of crSO₂ is maintained at a higher value than that of rSO₂ (B), and c-mDrSO₂ increases with the decrease in MAP. In the case of remarkable hypovolemia, blood flow to the brain decreases, and the value of crSO₂ also decreases. Thus, the values of crSO₂ and mrSO₂ are almost equal, and thus, c-mDrSO₂ decreases (A)

When we apply the diagram to our study, the case of healthy volunteers applies to (C). Case 1 shows that in patients with septic shock, MAP, crSO₂, and mrSO₂ change from (A) to (B) with the administration of fluid resuscitation and vasopressors. Case 2 shows that MAP, crSO₂, and mrSO₂ of the patients with septic shock change from (C) to (B). Case 3 shows that in patients with hypovolemic shock, MAP, crSO₂, and mrSO₂ change from (B) to (C) with the administration of red blood cells. The candidates for appropriately targeting MAP are those showing a change from (C) to (B) or from (A) to (B) to preserve major organ blood flow. We consider that stage I of the three stages of shock matches with (C), stage II matches with (B), and stage III matches with (A).

Our study showed that even if SpO₂ or blood pressure cannot be measured due to circulatory failure associated with shock, it is still possible to measure the values of crSO₂ and mrSO₂. Besides, because the values change in real time with fluctuation of the blood pressure, unlike with previous monitoring devices, the rSO₂ monitor may continuously and clearly reflect the changes in the local oxygen supply-demand balance. Further, simultaneous measurement of crSO₂ and mrSO₂ rather than either crSO₂ or mrSO₂ alone may be helpful as a real-time method for evaluating therapeutic effect.

A limitation of this study is the presence of selection bias associated with the choice of case reports used. We are continuing to accumulate additional cases and examining whether the simultaneous measurement of crSO₂ and mrSO₂ might be a useful method to evaluate adequate blood pressure in shock management.

In conclusion, we evaluated the usefulness of the simultaneous measurement of crSO₂ and mrSO₂ and found that it might be an objective and noninvasive method of evaluating blood pressure management in shock patients.

c-mDrSO₂: difference in cerebro-musculoskeletal regional saturation of oxygen; crSO₂: cerebral regional oxygen saturation; MAP: mean arterial pressure; mrSO₂: muscle regional oxygen saturation; rSO₂: regional oxygen saturation; SpO₂: pulse oximetric saturation.

Ethics approvals and consent to participate

The study protocol was approved by the Institutional Review Board of Osaka University (Approval Number: 19540), which waived the need to obtain patient written informed consent because of the observational nature of the study.

Consent for publication

The need to obtain patient written informed consent was waived because of the observational nature of the study.

Availability of data and materials

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Funding

This work received research funding from ZENKYOREN (National Mutual Insurance Federation of Agricultural Cooperatives).

Authors’ contributions

A.M., R.T., and M.O. conceived the study, and participated in its design. A.M., S.N., and J.T. collected and generated the data. A.M. wrote the first draft. T.H helped to draft the manuscript. All of the authors read and approved the final manuscript.

Acknowledgments

We gratefully acknowledge the devoted cooperation of the Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine.

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You are reading this latest preprint version

Usefulness of Simultaneous Measurement of Brain and Muscle rSO₂ (Regional Oxygen Saturation) in Shock Patients: a Report of Three Cases

Status:

Version 1

Abstract

Figures

Background

Case Presentations

Brain and muscle rSO₂ in healthy volunteers

Shock case 1

Shock case 2

Shock case 3

Discussion And Conclusion

Abbreviations

Declarations

References

Status:

Version 1

Usefulness of Simultaneous Measurement of Brain and Muscle rSO2 (Regional Oxygen Saturation) in Shock Patients: a Report of Three Cases

Status:

Version 1

Abstract

Figures

Background

Case Presentations

Brain and muscle rSO2 in healthy volunteers

Shock case 1

Shock case 2

Shock case 3

Discussion And Conclusion

Abbreviations

Declarations

References

Status:

Version 1

Usefulness of Simultaneous Measurement of Brain and Muscle rSO₂ (Regional Oxygen Saturation) in Shock Patients: a Report of Three Cases

Brain and muscle rSO₂ in healthy volunteers