Hemodynamic patterns preceding circulatory deterioration and death after trauma

Can central-venous oxygen saturation be estimated from tissue oxygen saturation during a venous occlusion test?

OBJECTIVE

To test whether tissue oxygen saturation (StO2) after a venous occlusion test estimates central venous oxygen saturation (ScvO2).

METHODS

Observational study in intensive care unit patients. Tissue oxygen saturation was monitored (InSpectra Tissue Spectrometer Model 650, Hutchinson Technology Inc., MN, USA) with a multiprobe (15/25mm) in the thenar position. A venous occlusion test in volunteers was applied in the upper arm to test the tolerability and pattern of StO2 changes during the venous occlusion test. A sphygmomanometer cuff was inflated to a pressure 30mmHg above diastolic pressure until StO2 reached a plateau and deflated to 0mmHg. Tissue oxygen saturation parameters were divided into resting StO2 (r-StO2) and minimal StO2 (m-StO2) at the end of the venous occlusion test. In patients, the cuff was inflated to a pressure 30mmHg above diastolic pressure for 5 min (volunteers' time derived) or until a StO2 plateau was reached. Tissue oxygen saturation parameters were divided into r-StO2, m-StO2, and the mean time that StO2 reached ScvO2. The StO2 value at the mean time was compared to ScvO2.

RESULTS

All 9 volunteers tolerated the venous occlusion test. The time for tolerability or the StO2 plateau was 7 ± 1 minutes. We studied 22 patients. The mean time for StO2 equalized ScvO2 was 100 sec and 95 sec (15/25mm probes). The StO2 value at 100 sec ([100-StO2] 15mm: 74 ± 7%; 25mm: 74 ± 6%) was then compared with ScvO2 (75 ± 6%). The StO2 value at 100 sec correlated with ScvO2 (15 mm: R2 = 0.63, 25mm: R2 = 0.67, p < 0.01) without discrepancy (Bland Altman).

CONCLUSION

Central venous oxygen saturation can be estimated from StO2 during a venous occlusion test.

Monitoring skin blood flow to rapidly identify alterations in tissue perfusion during fluid removal using continuous veno-venous hemofiltration in patients with circulatory shock

Background

Continuous veno-venous hemofiltration (CVVH) can be used to reduce fluid overload and tissue edema, but excessive fluid removal may impair tissue perfusion. Skin blood flow (SBF) alters rapidly in shock, so its measurement may be useful to help monitor tissue perfusion.

Methods

In a prospective, observational study in a 35-bed department of intensive care, all patients with shock who required fluid removal with CVVH were considered for inclusion. SBF was measured on the index finger using skin laser Doppler (Periflux 5000, Perimed, Järfälla, Sweden) for 3 min at baseline (before starting fluid removal, T0), and 1, 3 and 6 h after starting fluid removal. The same fluid removal rate was maintained throughout the study period. Patients were grouped according to absence (Group A) or presence (Group B) of altered tissue perfusion, defined as a 10% increase in blood lactate from T0 to T6 with the T6 lactate ≥ 1.5 mmol/l. Receiver operating characteristic curves were constructed and areas under the curve (AUROC) calculated to identify variables predictive of altered tissue perfusion. Data are reported as medians [25th–75th percentiles].

Results

We studied 42 patients (31 septic shock, 11 cardiogenic shock); median SOFA score at inclusion was 9 [8–12]. At T0, there were no significant differences in hemodynamic variables, norepinephrine dose, lactate concentration, ScvO₂ or ultrafiltration rate between groups A and B. Cardiac index and MAP did not change over time, but SBF decreased in both groups (p < 0.05) throughout the study period. The baseline SBF was lower (58[35–118] vs 119[57–178] perfusion units [PU], p = 0.03) and the decrease in SBF from T0 to T1 (ΔSBF%) higher (53[39–63] vs 21[12–24]%, p = 0.01) in group B than in group A. Baseline SBF and ΔSBF% predicted altered tissue perfusion with AUROCs of 0.83 and 0.96, respectively, with cut-offs for SBF of ≤ 57 PU (sensitivity 78%, specificity 87%) and ∆SBF% of ≥ 45% (sensitivity 92%, specificity 99%).

Conclusion

Baseline SBF and its early reduction after initiation of fluid removal using CVVH can predict worsened tissue perfusion, reflected by an increase in blood lactate levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00847-z.

Decreased peripheral perfusion measured by perfusion index is a novel indicator for cardiovascular death in patients with type 2 diabetes and established cardiovascular disease

Cardiovascular disease (CVD) is still the major cause of mortality in patients with type 2 diabetes. Despite of recent therapies, mortality and resources spent on healthcare due to CVD is still important problem. Thus, appropriate markers are needed to predict poor outcomes. Therefore, we investigated the role of peripheral perfusion as an indicator for cardiovascular death in patients with type 2 diabetes and established CVD. This retrospective cohort study included 1080 patients with type 2 diabetes and history of CVD recruited from the outpatient clinic at Matsushita Memorial Hospital in Osaka, Japan. Peripheral perfusion is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. The median age and PI values were 74 years (range: 67-79 years) and 2.6% (range: 1.1-4.3%), respectively. During follow-up duration, 60 patients died due to CVD. The adjusted Cox regression analysis demonstrated that the risk of developing cardiovascular death was higher in the first quartile (Hazard ratio, 6.23; 95% CI, 2.28 to 22.12) or second quartile (Hazard ratio, 3.04; 95% CI, 1.46 to 6.85) of PI than that in the highest quartile (fourth quartile) of PI. PI (per 1% decrease) was associated with the development of cardiovascular death (Hazard ratio, 1.39; 95% CI, 1.16 to 1.68). PI could be a novel indicator of cardiovascular death in patients with type 2 diabetes and established CVD.

Alterations in Skin Blood Flow at the Fingertip Are Related to Mortality in Patients With Circulatory Shock

OBJECTIVES

Skin blood flow is rapidly altered during circulatory shock and may remain altered despite apparent systemic hemodynamic stabilization. We evaluated whether changes in skin blood flow during circulatory shock were related to survival.

DESIGN

Prospective study.

SETTING

Thirty-five-bed medical-surgical university hospital department of intensive care.

SUBJECTS

Twenty healthy volunteers and 70 patients with circulatory shock (< 12 hr duration), defined as the need for vasopressors to maintain mean arterial pressure greater than or equal to 65 mm Hg and signs of altered tissue perfusion.

INTERVENTIONS

We assessed skin blood flow using skin laser Doppler on the fingertip for 3 minutes at basal temperature (SBFBT) and at 37°C (SBF37) (thermal challenge test) once in volunteers and at the time of inclusion and after 6, 24, 48, 72, and 96 hours in patients with shock. Capillary refill time and peripheral perfusion index were measured at the same time points on the contralateral hand.

MEASUREMENTS AND MAIN RESULTS

The thermal challenge response (ΔSBF/ΔT) was calculated using the following formula: (SBF37-SBFBT)/(37-basal temperature). Area under the receiver operating characteristic curves were calculated to evaluate variables predictive of ICU mortality. At inclusion, skin blood flow and ΔSBF/ΔT were lower in patients than in volunteers. Baseline skin blood flow (31 [17-113] vs 16 [9-32] arbitrary perfusion units; p = 0.01) and ΔSBF/ΔT (4.3 [1.7-10.9] vs 0.9 [0.4-2.9] arbitrary perfusion unit/s) were greater in survivors than in nonsurvivors. Capillary refill time was shorter in survivors than in nonsurvivors; peripheral perfusion index was similar in the two groups. ΔSBF/ΔT (area under the receiver operating characteristic curve 0.94 [0.88-0.99]) and SBFBT (area under the receiver operating characteristic curve 0.83 [0.73-0.93]) had the best predictive value for ICU mortality with cutoff values less than or equal to 1.25 arbitrary perfusion unit/°C (sensitivity 88%, specificity 89%) and less than or equal to 21 arbitrary perfusion unit (sensitivity 84%, specificity 81%), respectively.

CONCLUSIONS

Alterations in fingertip skin blood flow can be evaluated using a laser Doppler thermal challenge technique in patients with circulatory shock and are directly related to outcome. These novel monitoring techniques could potentially be used to guide resuscitation.

Decreased microcirculatory function measured by perfusion index is predictive of cardiovascular death

BACKGROUND

The importance of microcirculation for adverse outcomes in the early phase of critical illnesses has been reported. Microcirculatory function is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. We investigated the correlation between PI and cardiovascular death to explore whether it can serve as a predictor of cardiovascular death.

METHODS AND RESULTS

This retrospective study included 2171 patients admitted to Matsushita Memorial Hospital in Osaka, Japan, for medical treatment. We measured PI for all patients. To examine the effects of PI on cardiovascular death, a Cox proportional hazard model was used. The median age and PI values were 72 years (range 63-79 years) and 2.7% (range 1.4-4.6%), respectively. During the 3927.7 person-years follow-up period, a total of 54 patients died due to cardiovascular disease. PI was positively correlated with BMI (P < 0.0001) and total cholesterol levels (P = 0.004). PI was negatively correlated with age (P < 0.0001), heart rate (P < 0.0001), and creatinine levels (P < 0.0001). Adjusted Cox regression analyses demonstrated that PI was associated with an increased hazard of cardiovascular death (hazard ratio 0.84; 95% CI; range 0.72-0.99). In addition, compared with patients with a high PI (> 3.7%), those with a low PI (≤ 2.0%) had a significantly increased risk of cardiovascular death. This low PI group had a hazard ratio of 3.49 (95% CI 1.73-7.82).

CONCLUSIONS

The PI is a valuable predictor for cardiovascular death in a clinical setting.

Microvascular reactivity and clinical outcomes in cardiac surgery

Introduction

Microvascular reactivity is decreased in patients with septic shock; this is associated with worse clinical outcomes. The objectives of the present study were to investigate microvascular reactivity in cardiac surgery patients and to assess any association with clinical outcomes.

Methods

We retrospectively analyzed a prospectively collected registry. In total, 254 consecutive adult patients undergoing cardiac and thoracic aortic surgeries from January 2013 through May 2014 were analyzed. We performed a vascular occlusion test (VOT) by using near-infrared spectroscopy to measure microvascular reactivity. VOT was performed three times per patient: prior to the induction of anesthesia, at the end of surgery, and on postoperative day 1. The primary endpoint was a composite of major adverse complications, including death, myocardial infarction, acute kidney injury, acute respiratory distress syndrome, and persistent cardiogenic shock.

Results

VOT recovery slope decreased during the surgery. VOT recovery slope on postoperative day 1 was significantly lower in patients with composite complications than those without (3.1 ± 1.6 versus 4.0 ± 1.5 %/s, P = 0.001), although conventional hemodynamic values, such as cardiac output and blood pressure, did not differ between the groups. On multivariable regression and linear analyses, low VOT recovery slope on postoperative day 1 was associated with increases of composite complications (odds ratio 0.742; 95 % confidence interval (CI) 0.584 to 0.943; P = 0.015) and hospital length of stay (regression coefficient (B) −1.276; 95 % CI −2.440 to −0.112; P = 0.032).

Conclusion

Microvascular reactivity largely recovered on postoperative day 1 in the patients without composite complications, but this restoration was attenuated in patients with composite complications.

Trial registration

ClinicalTrials.gov NCT01713192. Registered 22 October 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1025-3) contains supplementary material, which is available to authorized users.

Indications for blood transfusion following trauma - a pilot study

Background: Indications for blood transfusion during trauma resuscitation remain poorly understood. This study aimed to objectively determine the range of factors that lead to initiation of blood transfusion during trauma resuscitation. Design and method: This was a prospective, observational pilot study. A questionnaire was distributed to all clinicians following any transfusion of packed red blood cells during trauma resuscitation. The questionnaire focused on the clinicians’ opinion regarding the indication for red cell transfusion. Results: Complete data on 37 individual episodes of transfusion initiation in the Emergency Department were collected. The most commonly used pre-hospital factors that influenced initiation of transfusion was a pre-hospital systolic blood pressure (SBP) of < 100 mm Hg (65%), pre-hospital tachycardia (38%) or estimated blood loss of >1 L (30%) by paramedics. On arrival to hospital, the activation of a massive transfusion protocol was the commonest indication for transfusion, followed by a positive FAST examination (43%), low systolic blood pressure (35%), tachycardia (32%) or pallor (35%). Blood tests to guide initiation of transfusion were less commonly used with 9 (24%) patients transfused for a low haemoglobin level and 6 (16%) patients transfused for coagulopathy. Conclusions: A combination of objective pre- and in-hospital vital signs, together with subjective indicators such as pallor and estimation of blood loss guided initiation of transfusion following injury.

Low StO2 measurements in surgical intensive care unit patients is associated with poor outcomes

BACKGROUND

Near-infrared spectroscopy-derived tissue hemoglobin saturation (StO2) is a noninvasive measurement that reflects changes in microcirculatory tissue perfusion. Previous studies in trauma patients have shown a correlation between low StO2 levels and mortality, organ failure, and severity of injury. The goals of this study were to identify the incidence of low StO2 in the critically ill patient population of a surgical intensive care unit (SICU) and evaluate the relationship of low StO2 and clinical outcomes.

METHODS

We conducted a prospective cohort study at the University of Minnesota Medical Center. After institutional review board approval, 620 patients admitted to the SICU between July 2010 and July 2011 were screened for enrollment. Patients with an expected ICU length of stay of less than 24 hours were excluded. In the 490 patients who met inclusion criteria, StO2 measurements were obtained from the thenar eminence one to three times daily for the length of the ICU stay, up to 14 days. Outcome data included 28-day hospital mortality; ICU readmission; ventilator-free, ICU-free, and hospital-free days; and the need for lifesaving interventions.

RESULTS

The overall incidence of low StO2 (<70%) was 11% of the patients per day. Patients with at least 1 day in the SICU with an StO2 measurement of less than 70% had higher rates of ICU readmission and fewer ventilator-free, ICU-free, and hospital-free days compared with those who did not. Mortality (28-day in-hospital) trended higher for these patients but was not statistically significant. An increase in the number of days with StO2 less than 70% was also associated with fewer ventilator-free, ICU-free, and hospital-free days.

CONCLUSION

Low StO2 (<70%) is common and associated with poor outcomes in SICU patients. Near-infrared spectroscopy represents a potentially useful, noninvasive adjunct to monitoring of critically ill patients.

LEVEL OF EVIDENCE

Prognostic study, level II.

The peripheral perfusion index and transcutaneous oxygen challenge test are predictive of mortality in septic patients after resuscitation

Introduction

The peripheral perfusion index (PI) is a noninvasive numerical value of peripheral perfusion, and the transcutaneous oxygen challenge test (OCT) is defined as the degree of transcutaneous partial pressure of oxygen (PtcO₂) response to 1.0 FiO_2. The value of noninvasive monitoring peripheral perfusion to predict outcome remains to be established in septic patients after resuscitation. Moreover, the prognostic value of PI has not been investigated in septic patients.

Methods

Forty-six septic patients, who were receiving PiCCO-Plus cardiac output monitoring, were included in the study group. Twenty stable postoperative patients were studied as a control group. All the patients inspired 1.0 of FiO₂ for 10 minutes during the OCT. Global hemodynamic variables, traditional metabolic variables, PI and OCT related-variables were measured simultaneously at 24 hours after PiCCO catheter insertion. We obtained the 10min-OCT ((PtcO₂ after 10 minutes on inspired 1.0 oxygen) - (baseline PtcO₂)), and the oxygen challenge index ((10min-OCT)/(PaO₂ on inspired 1.0 oxygen - baseline PaO₂)) during the OCT.

Results

The PI was significantly correlated with baseline PtcO₂, 10min-OCT and oxygen challenge index (OCI) in all the patients. The control group had a higher baseline PtcO₂, 10min-OCT and PI than the septic shock group. In the sepsis group, the macro hemodynamic parameters and ScvO₂ showed no differences between survivors and nonsurvivors. The nonsurvivors had a significantly lower PI, 10min-OCT and OCI, and higher arterial lactate level. The PI, 10min-OCT and OCI predicted the ICU mortality with an accuracy that was similar to arterial lactate level. A PI <0.2 and a 10min-OCT <66mmHg were related to poor outcome after resuscitation.

Conclusions

The PI and OCT are predictive of mortality for septic patients after resuscitation. Further investigations are required to determine whether the correction of an impaired level of peripheral perfusion may improve the outcome of septic shock patients.

Risk factors for vascular occlusive events and death due to bleeding in trauma patients; an analysis of the CRASH-2 cohort

BACKGROUND

Vascular occlusive events can complicate recovery following trauma. We examined risk factors for venous and arterial vascular occlusive events in trauma patients and the extent to which the risk of vascular occlusive events varies with the severity of bleeding.

METHODS AND FINDINGS

We conducted a cohort analysis using data from a large international, double-blind, randomised, placebo-controlled trial (The CRASH-2 trial) [1]. We studied the association between patient demographic and physiological parameters at hospital admission and the risk of vascular occlusive events. To assess the extent to which risk of vascular occlusive events varies with severity of bleeding, we constructed a prognostic model for the risk of death due to bleeding and assessed the relationship between risk of death due to bleeding and risk of vascular occlusive events. There were 20,127 trauma patients with outcome data including 204 (1.01%) patients with a venous event (pulmonary embolism or deep vein thrombosis) and 200 (0.99%) with an arterial event (myocardial infarction or stroke). There were 81 deaths due to vascular occlusive events. Increasing age, decreasing systolic blood pressure, increased respiratory rates, longer central capillary refill times, higher heart rates and lower Glasgow Coma Scores (all p<0.02) were strong risk factors for venous and arterial vascular occlusive events. Patients with more severe bleeding as assessed by predicted risk of haemorrhage death had a greatly increased risk for all types of vascular occlusive event (all p<0.001).

CONCLUSIONS

Patients with severe traumatic bleeding are at greatly increased risk of venous and arterial vascular occlusive events. Older age and blunt trauma are also risk factors for vascular occlusive events. Effective treatment of bleeding may reduce venous and arterial vascular occlusive complications in trauma patients.

Intrahospital Transport to the Radiology Department: Risk for Adverse Events, Nursing Surveillance, Utilization of a MET and Practice Implications

Nurses providing care in the Radiology Department (RD) are challenged by the broad scope of conditions and varied acuity of patients served by this unit. Nurses must facilitate the required diagnostic testing and simultaneously provide the surveillance necessary to detect physiologic changes signaling the need for rescue interventions. When instability occurs, one method of rescue involves activation of a Medical Emergency Team (MET) to bring an experienced cadre of critical care providers to the unstable patient. Despite recognition that the RD can be a high risk area, there is little in the literature specific to the surveillance of RD patients, risk for and prevention of adverse events, MET activation or the management of patient instability specific to the RD. The purpose of this paper is to examine what is known regarding risk for adverse events during intrahospital transport, utilization of a MET as a rescue intervention, and practice implications.

Cardiorespiratory instability before and after implementing an integrated monitoring system

OBJECTIVES

Cardiorespiratory instability may be undetected in monitored step-down unit patients. We explored whether using an integrated monitoring system that continuously amalgamates single noninvasive monitoring parameters (heart rate, respiratory rate, blood pressure, and peripheral oxygen saturation) into AN instability index value (INDEX) correlated with our single-parameter cardiorespiratory instability concern criteria, and whether nurse response to INDEX alert for patient attention was associated with instability reduction.

DESIGN

Prospective, longitudinal evaluation in sequential 8-, 16-, and 8-wk phases (phase I, phase II, and phase III, respectively).

SETTING

A 24-bed trauma step-down unit in single urban tertiary care center.

PATIENTS

All monitored patients.

INTERVENTIONS

Phase I: Patients received continuous single-channel monitoring (heart rate, respiratory rate, blood pressure, and peripheral oxygen saturation) and standard care; INDEX background was recorded but not displayed. Phase II: INDEX was background-recorded; staff was educated on use. Phase III: Staff used a clinical response algorithm for INDEX alerts.

MEASUREMENT AND MAIN RESULTS

Any monitored parameters even transiently beyond local cardiorespiratory instability concern triggers (heart rate of <40 or >140 beats/min, respiratory rate of <8 or >36 breaths/min, systolic blood pressure of <80 or >200 mm Hg, diastolic blood pressure of >110 mm Hg, and peripheral oxygen saturation of <85%) defined INSTABILITYmin. INSTABILITYmin further judged as both persistent and serious defined INSTABILITYfull. The INDEX alert states were defined as INDEXmin and INDEXfull by using same classification. Phase I and phase III admissions (323 vs. 308) and monitoring (18,258 vs. 18,314 hrs) were similar. INDEXmin and INDEXfull correlated significantly with INSTABILITYmin and INSTABILITYfull (r = .713 and r = .815, respectively, p < .0001). INDEXmin occurred before INSTABILITYmin in 80% of cases (mean advance time 9.4 ± 9.2 mins). Phase I and phase III admissions were similarly likely to develop INSTABILITYmin (35% vs. 33%), but INSTABILITYmin duration/admission decreased from phase I to phase III (p = .018). Both INSTABILITYfull episodes/admission (p = .03) and INSTABILITYfull duration/admission (p = .05) decreased in phase III.

CONCLUSION

The integrated monitoring system INDEX correlated significantly with cardiorespiratory instability concern criteria, usually occurred before overt instability, and when coupled with a nursing alert was associated with decreased cardiorespiratory instability concern criteria in step-down unit patients.

Factors associated with reduced longer-term capacity to work in patients after polytrauma: a Swiss trauma center experience

BACKGROUND

Knowledge of the factors associated with longer-term reduced capacity to work (RCW) is lacking in patients after polytrauma.

STUDY DESIGN

We studied a prospectively collected cohort of polytrauma survivors (n = 115; age 39.5 +/- 20.6 years [mean +/- SD]; 98% blunt trauma; Injury Severity Score [ISS] 27.5 +/- 8.2) at a university trauma center. Uni- and multivariable analyses of patient, trauma, and treatment characteristics as well as parameters of self-reported functional outcomes were studied to determine their association with a reduced capacity to work (RCW) at least 2 years after injury.

RESULTS

Postinjury quality of life was worse compared with preinjury status in univariate analysis (eg, Euro Quality of Life Group Visual Analogue Scale [EQ VAS] 66.2 +/- 24.4 vs 89.7 +/- 14.7; p = <0.001). In 53% of patients (n = 61), an RCW was found and functional outcomes were significantly lower than those in non-RCW patients (p < 0.001). Lower educational status (odds ratio [OR] 0.25; 95% CI 0.07 to 0.92; p = 0.036), higher ISS (OR 1.12; 95% CI 1.02 to 1.22; p = 0.017), less time in the emergency room (OR 0.92; 95% CI 0.86 to 0.97; p = 0.005), higher mean nurse labor per day and patient (OR 1.01; 95% CI 1.000 to 1.004; p = 0.033), and a reduced Nottingham Health Profile value (OR 1.10; 95% CI 1.06 to 1.15; p < 0.001) were associated with an RCW in the multiple logistic regression model (proportion of variance explained: 0.74).

CONCLUSIONS

In this cohort of patients surviving polytrauma, approximately 50% of patients sustained longer-term RCW. Several characteristics, such as level of education or trauma severity, showed an independent association with patients' capacity to work, which was significantly associated with patients' self-rated scorings of well-being.

Early identification of shock in critically ill patients

Emergency providers must be experts in the resuscitation and stabilization of critically ill patients, and the rapid recognition of shock is crucial to allow aggressive targeted intervention and reduce morbidity and mortality. This article reviews the physiologic definition of shock, the importance of early intervention, and the clinical and diagnostic signs that emergency department providers can use to identify patients in shock.

Low tissue oxygen saturation at the end of early goal-directed therapy is associated with worse outcome in critically ill patients

Introduction

The prognostic value of continuous monitoring of tissue oxygen saturation (StO₂) during early goal-directed therapy of critically ill patients has not been investigated. We conducted this prospective study to test the hypothesis that the persistence of low StO₂ levels following intensive care admission is related to adverse outcome.

Methods

We followed 22 critically ill patients admitted with increased lactate levels (>3 mmol/l). Near-infrared spectroscopy (NIRS) was used to measure the thenar eminence StO₂ and the rate of StO₂ increase (R_incStO₂) after a vascular occlusion test. NIRS dynamic measurements were recorded at intensive care admission and each 2-hour interval during 8 hours of resuscitation. All repeated StO₂ measurements were further compared with Sequential Organ Failure Assessment (SOFA), Acute Physiology and Chronic Health Evaluation (APACHE) II and hemodynamic physiological variables: heart rate (HR), mean arterial pressure (MAP), central venous oxygen saturation (ScvO₂) and parameters of peripheral circulation (physical examination and peripheral flow index (PFI)).

Results

Twelve patients were admitted with low StO₂ levels (StO₂ <70%). The mean scores for SOFA and APACHE II scores were significantly higher in patients who persisted with low StO₂ levels (n = 10) than in those who exhibited normal StO₂ levels (n = 12) at 8 hours after the resuscitation period (P < 0.05; median (interquartile range): SOFA, 8 (7 to 11) vs. 5 (3 to 8); APACHE II, 32(24 to 33) vs. 19 (15 to 25)). There was no significant relationship between StO₂ and mean global hemodynamic variables (HR, P = 0.26; MAP, P = 0.51; ScvO₂, P = 0.11). However, there was a strong association between StO₂ with clinical abnormalities of peripheral perfusion (P = 0.004), PFI (P = 0.005) and R_incStO₂ (P = 0.002). The persistence of low StO₂ values was associated with a low percentage of lactate decrease (P < 0.05; median (interquartile range): 33% (12 to 43%) vs. 43% (30 to 54%)).

Conclusions

We found that patients who consistently exhibited low StO₂ levels following an initial resuscitation had significantly worse organ failure than did patients with normal StO₂ values, and found that StO₂ changes had no relationship with global hemodynamic variables.

Surgical inflammation: a pathophysiological rainbow

Tetrapyrrole molecules are distributed in virtually all living organisms on Earth. In mammals, tetrapyrrole end products are closely linked to oxygen metabolism. Since increasingly complex trophic functional systems for using oxygen are considered in the post-traumatic inflammatory response, it can be suggested that tetrapyrrole molecules and, particularly their derived pigments, play a key role in modulating inflammation.

In this way, the diverse colorfulness that the inflammatory response triggers during its evolution would reflect the major pathophysiological importance of these pigments in each one of its phases. Therefore, the need of exploiting this color resource could be considered for both the diagnosis and treatment of the inflammation.