Measurements of Subcutaneous Tissue PO&lt;sub&gt;2&lt;/sub&gt; Reflect Oxygen Metabolism of the Small Intestinal Mucosa during Hemorrhage and Resuscitation

Mellström, Å.; Månsson, Peter; Jonsson, Kjell; Hartmann, Michael

doi:10.1159/000193295

Cited by 11 publications

(5 citation statements)

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“…Intestinal pO 2 measured using a polarographic oxygen electrode placed in direct contact with the serosa of the ileum yielded baseline results similar to ours, 52± 8 [17] versus 55.5 ± 11 mmHg. The pO 2 on day 1 increased for the majority of control and SMA-banded rats.…”

Section: Discussionsupporting

confidence: 82%

Noninvasive Monitoring of Small Intestinal Oxygen in a Rat Model of Chronic Mesenteric Ischemia

Khan

Salisbury

et al. 2013

Cell Biochem Biophys

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We noninvasively monitored the partial pressure of oxygen (pO2) in rat small intestine using a model of chronic mesenteric ischemia by electron paramagnetic resonance oximetry (EPR) over a 7-day period. The particulate probe lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) was embedded into the oxygen permeable material polydimethyl siloxane (PDMS) by cast-molding and polymerization (Oxy-Chip). A one-time surgical procedure was performed to place the Oxy-Chip on the outer wall of the small intestine (SI). The superior mesenteric artery (SMA) was banded to approximately 30% blood flow for experimental rats. Noninvasive measurement of pO2 was performed at baseline for control rats or immediate post-banding and on days 1, 3, and 7. The SI pO2 for control rats remained stable over the 7-day period. The pO2 on day 7 was 54.5 ± 0.9 mmHg (mean ± SE). SMA banded rats were significantly different from controls with a noted reduction in pO2 post banding with a progressive decline to a final pO2 of 20.9 ± 4.5 mmHg (mean ± SE; p = 0.02). All SMA-banded rats developed adhesions around the Oxy-Chip yet remained asymptomatic. The hypoxia marker Hypoxyprobe™ was used to validate low tissue pO2. Brown cytoplasmic staining was consistent with hypoxia. Mild brown staining was noted predominantly on the villus tips in control animals. SMA-banded rats had an extended region of hypoxic involvement in the villus with a higher intensity of cytoplasmic staining. Deep brown staining of the enteric nervous system neurons and connective tissue both within layers and in the mesentery were noted. SMA banded rats with lower pO2 values had a higher intensity of staining. Thus, monitoring SI pO2 using the probe Oxy-Chip provides a valid measure of tissue oxygenation. Tracking pO2 in conditions that produce chronic mesenteric ischemia will contribute to our understanding of intestinal tissue oxygenation and how changes impact symptom evolution and the trajectory of chronic disease.

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Section: Discussionsupporting

confidence: 82%

Noninvasive Monitoring of Small Intestinal Oxygen in a Rat Model of Chronic Mesenteric Ischemia

Khan

Salisbury

et al. 2013

Cell Biochem Biophys

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“…However, whereas resuscitation after induced abnormalities in gastric tonometry has shown promise in animal studies (15–17), prospective studies of protocols aimed at improving splanchnic circulation have not consistently shown patient outcome benefit (18–22). Use of gastric tonometry has been impeded partially by confounding factors such as the effects of temperature (23) and pH (24) on hemoglobin affinity for CO 2 , and due to the discontinuous measurement of the method, which can take more than 10 min to acquire.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Multiple Modes of Oximetry Monitoring as an Index of Splanchnic Blood Flow in a Newborn Lamb Model of Hypoxic, Ischemic, and Hemorrhagic Stress

Ramsingh¹,

Dorotta²,

Sanghvi³

et al. 2013

Shock

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Early and aggressive treatment of circulatory failure is associated with increased survival, highlighting the need for monitoring methods capable of early detection. Vasoconstriction and decreased oxygenation of the splanchnic circulation are a sentinel response of the cardiovasculature during circulatory distress. Thus, we measured esophageal oxygenation as an index of decreased tissue oxygen delivery caused by three types of ischemic insult, occlusive decreases in mesenteric blood flow, and hemodynamic adaptations to systemic hypoxia and simulated hemorrhagic stress. Five anesthetized lambs were instrumented for monitoring of mean arterial pressure, mesenteric artery blood flow, central venous hemoglobin oxygen saturation, and esophageal and buccal microvascular hemoglobin oxygen saturation (StO2). The sensitivities of oximetry monitoring to detect cardiovascular insult were assessed by observing responses to graded occlusion of the descending aorta, systemic hypoxia due to decreased FIO2, and acute hemorrhage. Decreases in mesenteric artery flow during aortic occlusions were correlated with decreased esophageal StO2 (R2 = 0.41). During hypoxia, esophageal StO2 decreased significantly within 1 min of initiation, whereas buccal StO2 decreased within 3 min, and central venous saturation did not change significantly. All modes of oximetry monitoring and arterial blood pressure were correlated with mesenteric artery flow during acute hemorrhage. Esophageal StO2 demonstrated a greater decrease from baseline levels as well as a more rapid return to baseline levels during reinfusion of the withdrawn blood. These experiments suggest that monitoring esophageal StO2 may be useful in the detection of decreased mesenteric oxygen delivery as may occur in conditions associated with hypoperfusion or hypoxia.

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“…The perfusion of the intestinal organs remained unchanged until a total blood loss of 37% of the calculated total blood volume resulted in cardiac index and blood pressure values of less than 40 ± 3 ml/kg/min and 51 ± 5 mmHg, respectively. In dogs, pigs and rats it has been shown that in a hypovolemic situation the perfusion of the skin, the skeletal muscles and the gastrointestinal tract is not a priority and is disproportionally reduced compared to the muscle tissue [ 34 – 36 ]. In contrast a study with nine healthy horses under isoflurane anesthesia showed that gastrointestinal perfusion was preserved until a threshold blood pressure of about 60 mmHg or cardiac output lower 50 mL/kg /min were reached [ 6 ].…”

Section: Discussionmentioning

confidence: 99%

Effects of controlled hypoxemia or hypovolemia on global and intestinal oxygenation and perfusion in isoflurane anesthetized horses receiving an alpha-2-agonist infusion

et al. 2017

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BackgroundAim of this prospective experimental study was to assess effects of systemic hypoxemia and hypovolemia on global and gastrointestinal oxygenation and perfusion in anesthetized horses. Therefore, we anesthetized twelve systemically healthy warmblood horses using either xylazine or dexmedetomidine for premedication and midazolam and ketamine for induction. Anesthesia was maintained using isoflurane in oxygen with either xylazine or dexmedetomidine and horses were ventilated to normocapnia. During part A arterial oxygen saturation (SaO2) was reduced by reducing inspiratory oxygen fraction in steps of 5%. In part B hypovolemia was induced by controlled arterial exsanguination via roller pump (rate: 38 ml/kg/h). Mean arterial blood pressure (MAP), heart rate, pulmonary artery pressure, arterial and central venous blood gases and cardiac output were measured, cardiac index (CI) was calculated. Intestinal microperfusion and oxygenation were measured using laser Doppler flowmetry and white-light spectrophotometry. Surface probes were placed via median laparotomy on the stomach, jejunum and colon.ResultsPart A: Reduction in arterial oxygenation resulted in a sigmoid decrease in central venous oxygen partial pressure. At SaO2 < 80% no further decrease in central venous oxygen partial pressure occurred. Intestinal oxygenation remained unchanged until SaO2 of 80% and then decreased. Heart rate and pulmonary artery pressure increased significantly during hypoxemia. Part B: Progressive reduction in circulating blood volume resulted in a linear decrease in MAP and CI. Intestinal perfusion was preserved until blood loss resulted in MAP and CI lower 51 ± 5 mmHg and 40 ± 3 mL/kg/min, respectively, and then decreased rapidly.ConclusionsUnder isoflurane, intestinal tissue oxygenation remained at baseline when arterial oxygenation exceeded 80% and intestinal perfusion remained at baseline when MAP exceeded 51 mmHg and CI exceeded 40 mL/kg/min in this group of horses.Trial registry number33.14-42,502-04-14/1547.

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Measurements of Subcutaneous Tissue PO<sub>2</sub> Reflect Oxygen Metabolism of the Small Intestinal Mucosa during Hemorrhage and Resuscitation

Cited by 11 publications

References 58 publications

Noninvasive Monitoring of Small Intestinal Oxygen in a Rat Model of Chronic Mesenteric Ischemia

Noninvasive Monitoring of Small Intestinal Oxygen in a Rat Model of Chronic Mesenteric Ischemia

Evaluation of Multiple Modes of Oximetry Monitoring as an Index of Splanchnic Blood Flow in a Newborn Lamb Model of Hypoxic, Ischemic, and Hemorrhagic Stress

Effects of controlled hypoxemia or hypovolemia on global and intestinal oxygenation and perfusion in isoflurane anesthetized horses receiving an alpha-2-agonist infusion

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