Subcutaneous Tissue Oxygen Research Articles

Assessment of Microcirculatory Dysfunction by Measuring Subcutaneous Tissue Oxygen Saturation Using Near-Infrared Spectroscopy in Patients with Circulatory Failure.

Patients with circulatory failure have high mortality rates and require prompt assessment of microcirculation. Despite the improvement in hemodynamic parameters, microcirculatory dysfunction persists. We measured subcutaneous regional tissue oxygen saturation (rSO2) with near-infrared spectroscopy (NIRS), which can assess microcirculation in patients with circulatory failure. A finger-worn oximeter with NIRS measured rSO2 in the forehead, thenar eminence, thumb, and knees. First, the rSO2 was measured in healthy adult volunteers (n = 10). Circulatory failure was defined as a systolic blood pressure ≤ 90 mmHg and lactate ≥ 2 mmol/L. The study included 35 patients without circulatory failure and SOFA score of 0 at ICU admission and 38 patients with circulatory failure at ICU admission. Both groups included a single-center prospective study of patients who were transported to the ICU of the Nihon University Hospital. The rSO2 was measured only on ICU admission in the non-circulatory failure group and later in the circulatory failure group. In the volunteer group, rSO2 at each site was approximately 58%. The rSO2 was significantly lower in the circulatory failure group than in the non-circulatory failure group (knee, p < 0.01). In the circulatory failure group, knee rSO2 showed a significant negative correlation with SOFA score (Day 0, ρ = -0.37, p = 0.02; Day 1, ρ = -0.53, p < 0.01; Day 2, ρ = -0.60, p < 0.01). Subcutaneous knee rSO2 was associated with SOFA score and was considered an indicator of microcirculatory dysfunction and organ damage.

Multimodal Photoacoustic/Elastography Imaging for the Detection of Acute Radiation Dermatitis in Breast Radiation Therapy

Purpose: This study evaluates whether photoacoustic (PA), sound touch elastography (STE), and viscoelasticity (VE) can distinguish between normal and abnormal post-radiotherapy breast skin and compare these methods with RTOG criteria at a 20 Gy threshold. Methods: Patients meeting inclusion and exclusion criteria underwent PA, STE, and VE on the same day. Collected data included radiation dose, molecular type, RTOG, Fitzpatrick skin type, pathology, neoadjuvant chemotherapy status, TNM classification, surgical procedures, primary breast cancer location, BMI, and age. A sample of 41 patients was determined using a two-sample t-test. Statistical tools like T-tests, variance analysis, rank sum tests, and chi-square tests, along with random forest analysis and ROC curves, were used to evaluate the radiation dose effects. Results: Data from 66 patients showed significant differences in parameters such as dermis and subcutaneous tissue oxygen saturation, dermal thickness, and skin elasticity (p-values < 0.05). However, minimum values of oxygen saturation and some photoacoustic measures were not significantly different. Notably, at a 20 Gy radiation threshold, significant variations in oxygen saturation, abnormal dermal thickness, and skin STE and VE were observed, proving more accurate than RTOG grading. Conclusion: The study confirms the effectiveness of PA and elastography imaging in differentiating normal from abnormal breast tissue and assessing radiation-induced changes, highlighting the potential of these imaging techniques.

SMOKING AND FLAP SURVIVAL: A COMPREHENSIVE SYSTEMATIC REVIEW

Background: Free flap reconstruction of complex and/or large wounds, whether traumatic, following cancer resection, or for other reconstructive needs has become a commonly accepted practice. Multiple different types of free flaps are utilized for varying needs based on the individual patient and the defect that requires coverage. active smokers who underwent a nonelective traumatic reconstruction with a perforator-based fasciocutaneous flap (anterolateral thigh [ALT] flap) will have a higher incidence of smoking-related complications compared to the use of a muscle-only flap. The aim: The aim of this study to show about smoking and flap survival. Methods: By the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020, this study was able to show that it met all of the requirements. This search approach, publications that came out between 2014 and 2024 were taken into account. Several different online reference sources, like Pubmed, SagePub, and Google Scholar were used to do this. It was decided not to take into account review pieces, works that had already been published, or works that were only half done. Result: In the PubMed database, the results of our search get 9 articles, whereas the results of our search on SagePub get 441 articles, on Google Scholar 4830 articles. Records remove before screening are 2771, so we get 2509 articles fos screening. After we screened based on record exclude, we compiled a total of 10 papers. We included five research that met the criteria. Conclusion: Smoking decreases the alveolar oxygen pressure and subcutaneous wound tissue oxygen, and nicotine causes vasoconstriction, smokers are more likely to experience flap loss, hematoma, or fat necrosis than non-smokers. Preoperative and post-operative abstinence period of at least 1 week is necessary for smokers who undergo flap operations.

Abstract 14998: Assessment of Microcirculatory Dysfunction by Measuring Subcutaneous Tissue Oxygen Saturation Using Near-Infrared Spectroscopy in Patients With Circulatory Failure

Background: Patients with circulatory failure have been treated with the goal of normalizing systemic hemodynamic parameters such as blood pressure, central venous pressure, urine output, and central venous oxygen saturation. However, microcirculatory dysfunction remains even after improvement of these indices, suggesting a loss of hemodynamic coherence between the macrocirculation and the microcirculation. Recently, the usefulness of near-infrared spectroscopy (NIRS) in assessing the microcirculation has been reported. Aim: We measure regional tissue oxygenation saturation (rSO 2 ) at 3 - 5 mm subcutaneously in patients with circulatory failure using a finger-mounted tissue oximeter with the NIRS technique (Toccare: Astem Co., Ltd., Kawasaki, Japan) to investigate its relationship with microcirculation. Methods: This is a single-center prospective observational cohort study of patients with circulatory failure (systolic blood pressure ≤ 90 mmHg or lactate ≥ 2 mmol/L at presentation) transported to the emergency department of Nihon University Hospital from 15 June 2020 to 31 March 2022. We measured rSO 2 in the forehead, thenar eminence, thumb and knee using Toccare and assessed the relationship between rSO 2 and blood pressure, acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score and mottling score. Result: In patients with circulatory failure (n = 38), rSO 2 at each site showed no correlation with blood pressure, a negative correlation with SOFA score and APACHE II score and a positive correlation with mottling score. These significant correlations were also best observed in the knee. Conclusion: In patients with circulatory failure, rSO 2 measured with Toccare showed no correlation with blood pressure but a significant negative correlation with the severity of organ damage. The knee is possibly the optimal measurement site for monitoring microcirculatory dysfunction and determining the effectiveness of treatment.

Regional tissue oxygen saturation as a predictor of post-spinal anesthesia hypotension for cesarean delivery.

Regional tissue oxygen saturation as a predictor of post-spinal anesthesia hypotension for cesarean delivery.

Effect of Intraoperative Goal-Directed Fluid Management on Tissue Oxygen Tension in Obese Patients: a Randomized Controlled Trial

BackgroundPerioperative subcutaneous tissue oxygen tension (PsqO2) is substantially reduced in obese surgical patients. Goal-directed fluid therapy optimizes cardiac performance and thus tissue perfusion and oxygen delivery. We therefore tested the hypothesis that intra- and postoperative PsqO2 is significantly reduced in obese patients undergoing standard fluid management compared to goal-directed fluid administration.MethodsWe randomly assigned 60 obese patients (BMI ≥ 30 kg/m2) undergoing laparoscopic bariatric surgery to receive either esophageal Doppler-guided goal-directed fluid management or conventional fluid treatment. Our primary outcome parameter was intra- and postoperative PsqO2 measured with a polarographic electrode in the subcutaneous tissue of the upper arm. A random effects linear regression model was used to analyze the effect of intervention.ResultsOverall, mean (± SD) PsqO2 was significantly higher in obese patients receiving goal-directed therapy compared to conventional fluid therapy (65.8 ± 28.0 mmHg vs. 53.7 ± 21.7, respectively; repeated measures design adjusted difference: 13.0 mmHg [95% CI 2.3 to 23.7; p = 0.017]). No effect was seen intraoperatively (69.6 ± 27.9 mmHg vs. 61.4 ± 28.8, difference: 9.7 mmHg [95% CI -3.8 to 23.2; p = 0.160]); however, goal-directed fluid management improved PsqO2 in the early postoperative phase (63.1 ± 27.9 mmHg vs. 48.4 ± 12.5, difference: 14.5 mmHg [95% CI 4.1 to 24.9; p = 0.006]). Intraoperative fluid requirements did not differ between the two groups.ConclusionsGoal-directed fluid therapy improved subcutaneous tissue oxygenation in obese patients. This effect was more pronounced in the early postoperative period.Clinical Trial Number and RegistryThe study was registered at ClinicalTrials.gov (NCT 01052519).

Assessing changes in tissue oxygenation by near-infrared spectroscopy following brachial plexus block for arteriovenous fistula surgery: A prospective observational pilot study.

Near-infrared spectroscopy (NIRS) can be used to measure tissue oxygen saturation (StO2) in different sites and in a wide range of clinical scenarios. Peripheral regional anaesthesia induces vascular changes causing increased arterial blood flow and venodilatation, but its effect on StO2 is still under debate. This is especially so for patients undergoing arteriovenous fistula surgery, wherein latest data suggest an improved outcome under brachial plexus block (BPB) compared with local anaesthesia, but no data are available. The aim of this study was to investigate changes in StO2 following BPB prior to arteriovenous fistula surgery using NIRS. A prospective observational study. A secondary teaching hospital from August 2016 to March 2017. Fifteen patients undergoing arteriovenous fistula surgery. Ultrasound-guided BPB in 15 patients undergoing arteriovenous fistula surgery. StO2 at baseline and compared with baseline and the contralateral arm following BPB measured using NIRS of the thenar eminence (NIRSth). Baseline values of StO2 assessed by NIRSth were 42.6 ± 7.7% in the arteriovenous fistula arm and 42.7 ± 9.7% in the contralateral arm. There was no significant difference between the two. Five minutes after BPB, there was a significant increase in StO2 of the blocked arm, compared with the control arm expressed as difference of absolute values (7.1 ± 9.7%). At 60 min, an absolute difference of 21.0 ± 13.5% was reached. The absolute increase in StO2 of the blocked arm compared with baseline reached significance after 5 min (8.8 ± 4.6%) and increased up to 23.2 ± 8.2% after 60 min. NIRSth indicates that BPB significantly increases StO2 of the arteriovenous fistula arm in patients undergoing haemodialysis. Clinicaltrials.gov: NCT03044496.

Smoking and Flap Survival

The aim of this study was to compare the complications of flap surgery in non-smokers and smokers and to determine how the incidence of complications was affected by the abstinence period from smoking before and after flap surgery. In PubMed and Scopus, terms "smoking" and "flap survival" were used, which resulted in 113 papers and 65 papers, respectively. After excluding 6 duplicate titles, 172 titles were reviewed. Among them, 45 abstracts were excluded, 20 full papers were reviewed, and finally 15 papers were analyzed. Post-operative complications such as flap necrosis (P < .001), hematoma (P < .001), and fat necrosis (P = .003) occurred significantly more frequently in smokers than in non-smokers. The flap loss rate was significantly higher in smokers who were abstinent for 24 hours post-operatively than in non-smokers (n = 1464, odds ratio [OR] = 4.885, 95% confidence interval [CI] = 2.071-11.524, P < .001). The flap loss rate was significantly lower in smokers who were abstinent for 1 week post-operatively than in those who were abstinent for 24 hours post-operatively (n = 131, OR = 0.252, 95% CI = 0.074-0.851, P = .027). No significant difference in flap loss was found between non-smokers and smokers who were abstinent for 1 week preoperatively (n = 1519, OR = 1.229, 95% CI = 0.482-3.134, P = .666) or for 4 weeks preoperatively (n = 1576, OR = 1.902, 95% CI = 0.383-2.119, P = .812). Since smoking decreases the alveolar oxygen pressure and subcutaneous wound tissue oxygen, and nicotine causes vasoconstriction, smokers are more likely to experience flap loss, hematoma, or fat necrosis than non-smokers. Preoperative and post-operative abstinence period of at least 1 week is necessary for smokers who undergo flap operations.

548 Real-time continuous monitoring of subcutaneous tissue oxygenation

548 Real-time continuous monitoring of subcutaneous tissue oxygenation

Erythrocyte Storage Duration Is Not Associated with Increased Mortality in Noncardiac Surgical Patients

More than 5 million patients receive erythrocyte transfusions in the United States every year. Previous studies linked the storage duration of allogeneic erythrocytes to the risk of severe postoperative complications, especially after cardiac or trauma surgery. Limited data are available for noncardiac surgical patients. We therefore evaluated the association between storage duration of transfused erythrocytes and postoperative all-cause mortality among general surgery patients. Perioperative data corresponding to 63,319 adult, general surgery patients were obtained from our registry and merged with blood product data. Patients receiving solely leukocyte-reduced, allogeneic erythrocyte transfusions were included. Multivariable Cox proportional hazards regression was used to characterize the relationship between median erythrocyte storage duration and postoperative mortality rate, adjusting for characteristics plausibly influencing the storage duration of erythrocytes. Of the 6,994 patients included in the final analysis, 23, 44, 11, 9, and 13% received 1, 2, 3, 4, and ≥5 erythrocyte units, respectively. The authors found no evidence that increasing median storage duration was associated with a difference in the risk of postoperative mortality (hazard ratio, 0.99 [0.94-1.04]; P = 0.64). Analyzing the mean storage duration of erythrocyte units as a function of year of transfusion, the authors demonstrate a relevant decrease in utilization of the oldest blood units, whereas young blood storage duration remains nearly unchanged. The authors' study supports the recent literature in surgical and medical patients and underlines the importance of sufficiently powered randomized trials to finally resolve the erythrocyte storage duration debate.

Early Postoperative Subcutaneous Tissue Oxygen Predicts Surgical Site Infection

To the EditorRegarding the recent study by Akca et al.,1 investigating whether early postoperative subcutaneous tissue oxygen predicts surgical site infection, the authors did not check baseline StO2 in study group patients before start of surgery to see whether there was a difference among surgical

Early Postoperative Subcutaneous Tissue Oxygen Predicts Surgical Site Infection

Early Postoperative Subcutaneous Tissue Oxygen Predicts Surgical Site Infection

Supplemental oxygen reduces serotonin levels in plasma and platelets during colorectal surgery and reduces postoperative nausea and vomiting

it has been shown that supplemental oxygen reduces the incidence of postoperative nausea and vomiting (PONV) in patients undergoing colon surgery. Serotonin is a potent trigger of PONV. Theoretically, supplemental oxygen decreases gut ischaemia during surgery and in this way minimizes the release of serotonin. We investigated the release of serotonin during and after colorectal surgery with normal and supplemental oxygen administration. patients (n = 53) undergoing colon surgery were randomly assigned to one of two intraoperative ventilation regimens: group A (n = 30) received 80% oxygen and 20% nitrogen mixed with desflurane and group B (n = 23) received 30% oxygen and 70% nitrogen mixed with desflurane. To verify oxygenation status, we measured the arterial oxygen partial pressure (pO2) by blood gas analysis and the intramuscular tissue oxygenation using a polarographic microoxygen sensor (Licox, GMS, Mielkendorf, Germany). Serotonin levels in plasma and in platelets were measured using high-performance liquid chromatography (HPLC) before the beginning of surgery (T0), at the end of surgery (T1), and 2 h (T2), 8 h (T3) and 24 h (T4) postoperatively. PONV was assessed in the early (0-4 h) and overall (0-24 h) postoperative period by an anaesthesiologist unaware of patients' treatment regime. at T1, T2 and T3, serotonin levels were significantly (T1 '80% group' 80 ± 68.2 vs. '30% group' 147 ± 130.5; T2 '80% group' 78.4 ± 61 vs. '30% group' 139 ± 103; T3 '80% group' 76.2 ± 49.5 vs. '30% group' 124 ± 73.7; P < 0.05) reduced in the '80% oxygen group'. Patients in the '80% group' showed a significantly higher pO2 and subcutaneous tissue oxygenation (ptO2). The overall incidence of PONV was significantly reduced in the '80% oxygen group' ('80% group' 7% vs. '30% group' 35%). an inspired oxygen fraction of 0.8 reduces serotonin levels significantly and decreases PONV significantly in patients undergoing colon surgery.

Early Postoperative Subcutaneous Tissue Oxygen Predicts Surgical Site Infection

Subcutaneous oxygen partial pressure is one of several determinants of surgical site infections (SSIs). However, tissue partial pressure is difficult to measure and requires invasive techniques. We tested the hypothesis that early postoperative tissue oxygen saturation (Sto(2)) measured with near-infrared spectroscopy predicts SSI. We evaluated Sto(2) in 116 patients undergoing elective colon resection. Saturation was measured near the surgical incision, at the upper arm, and at the thenar muscle with an InSpectra™ tissue spectrometer model 650 (Hutchinson Technology Inc., Hutchinson, MN) 75 minutes after the end of surgery and on the first postoperative day. An investigator blinded to Sto(2) assessed patients daily for wound infection. Receiver operating characteristic curves were used to analyze the performance of Sto(2) measurements as a predictor of SSI. In 23 patients (≈ 20%), SSI was diagnosed 9 ± 5 days (mean ± SD) after surgery. Patients who did and did not develop an SSI had similar age (48 ± 14 vs 48 ± 15 years, respectively; P = 0.97) and gender (female:male, 15:8 vs 46:47, respectively), but patients who developed SSI weighed more (body mass index 32 ± 7 vs 27 ± 6 kg/m(2); P < 0.01). Sto(2) at the upper arm was lower in patients who developed SSI than in those who did not develop SSI (52 ± 22 vs 66 ± 21; P = 0.033), and these measurements had a sensitivity of 71% and specificity of 60% for predicting SSI, using Sto(2) of 66% as the cutoff point. Sto(2) measured at the upper arm only 75 minutes after colorectal surgery predicted development of postoperative SSI, although the infections were typically diagnosed more than a week later. Although further testing is required, Sto(2) measurements may be able to predict SSI and thus allow earlier preventive measures to be implemented.

Supplemental Postoperative Oxygen and Tissue Oxygen Tension in Morbidly Obese Patients

Subcutaneous tissue oxygen tension (PsqO(2)) is a major predictor for wound healing and the occurrence of wound infections. Perioperative subcutaneous wound and tissue oxygen tension is significantly reduced in morbidly obese patients. Even during intraoperative supplemental oxygen administration, PsqO(2) remains low. Tissue hypoxia is pronounced during surgery and might explain the substantial increase in infection risk in obese patients. It remains unknown whether long-term supplemental postoperative oxygen augments tissue oxygen tension. Consequently, we tested the hypothesis that 80% inspired oxygen administration during 12-18 postoperative hours significantly increases PsqO(2) compared to 30% inspired oxygen fraction. After IRB approval and informed consent, 42 patients undergoing laparoscopic bariatric surgery were randomly assigned to receive either 80% inspired oxygen via a PULMANEX Hi-Ox Mask (Viasys MedSystems, Wheeling, IL) (10 L/min) or 30% oxygen via nasal cannula (2 L/min) after surgery until the next morning. PsqO(2) was measured with a temperature-corrected Clark-type electrode in the subcutaneous tissue of the upper arm and adjacent to the wound. Postoperative subcutaneous tissue oxygen tension was significantly increased in the Hi-Ox group: 58 (47.7, 74.1) mmHg vs. 43 (38.7, 55.2) mmHg, P = 0.002. Also, wound tissue oxygen tension was improved during supplemental oxygen administration: 75.2 (69.8, 95.5) mmHg vs. 52.4 (46.3, 66.1) mmHg, P < 0.001. Subcutaneous tissue oxygen tension was significantly increased by supplemental postoperative oxygen administration. Whether there is an effect on the incidence of wound infection in morbidly obese patients is matter of further research.

Increased fluid intake does not augment capacity to lay down new collagen in nursing home residents at risk for pressure ulcers: A randomized, controlled clinical trial

Prevention of pressure ulcers is fundamental to safe care of nursing home residents yet the role of hydration in pressure ulcer prevention has not been systematically examined. This randomized clinical trial was undertaken to determine whether administration of supplemental fluid to nursing home residents at risk for pressure ulcers would enhance collagen deposition, increase estimated total body water, augment subcutaneous tissue oxygenation, and was safe. After a baseline period, 64 subjects were randomized to receive the fluid volume prescribed or additional fluid (prescribed plus 10 mL/kg) for 5 days. Participants' potential to heal as measured with hydroxyproline was low at baseline and did not increase significantly during treatment when additional fluid was systematically provided. Fluid intake increased significantly during treatment. Estimates of total body water and subcutaneous oxygen did not increase, indicating hydration was not improved. Supplemental fluid did not result in overhydration as measured by clinical parameters. Further work is needed to examine the relationship between fluid intake and hydration in nursing home residents as well as the role of hydration in pressure ulcer prevention.

Analysis of healthy sitting behavior: Interface pressure distribution and subcutaneous tissue oxygenation

Pressure ulcers are a large problem in individuals who use a wheelchair for their mobility and have limited trunk stability and motor function. Because no relation between interface pressure and pressure ulcer development has been established and no clinical threshold for pressure ulcer development can be given, looking at the sitting behavior of nondisabled individuals is important. Nondisabled individuals do not develop pressure ulcers because they continuously shift posture. We analyzed the sitting behavior of 25 nondisabled male subjects by using a combination of interface pressure measurement and subcutaneous tissue oxygenation measurement by means of the Oxygen to See. These subjects shifted posture on average 7.8 +/- 5.2 times an hour. These posture shifts were merely a combination of posture shifts in the frontal and sagittal plane. Subcutaneous oxygen saturation increased on average 2.2% with each posture adjustment, indicating a positive effect of posture shifts on tissue viability. The results of this study can be used as a reference for seating interventions aimed at preventing pressure ulcers. Changing the sitting load at least every 8 minutes is recommended for wheelchair users.

Subcutaneous Oxygen Pressure in Spontaneously Breathing Lean and Obese Volunteers: a Pilot Study

Oxidative killing is the primary defense against surgical pathogens; risk of infection is inversely related to tissue oxygenation. Subcutaneous tissue oxygenation in obese patients is significantly less than in lean patients during general anesthesia. However, it remains unknown whether reduced intraoperative tissue oxygenation in obese patients results from obesity per se or from a combination of anesthesia and surgery. In a pilot study, we tested the hypothesis that tissue oxygenation is reduced in spontaneously breathing, unanesthetized obese volunteers. Seven lean volunteers with a body mass index (BMI) of 22 +/- 2 kg/m(2) were compared to seven volunteers with a BMI of 46 +/- 4 kg/m(2). Volunteers were subjected to the following oxygen challenges: (1) room air; (2) 2 l/min oxygen via nasal prongs, (3) 6 l/min oxygen through a rebreathing face mask; (4) oxygen as needed to achieve an arterial oxygen pressure (arterial pO(2)) of 200 mmHg; and (5) oxygen as needed to achieve an arterial pO(2) of 300 mmHg. The oxygen challenges were randomized. Arterial pO(2) was measured with a continuous intraarterial blood gas analyzer (Paratrend 7); deltoid subcutaneous tissue oxygenation was measured with a polarographic microoxygen sensor (Licox). Subcutaneous tissue oxygenation was similar in lean and obese volunteers: (1) room air, 52 +/- 10 vs 58 +/- 8 mmHg; (2) 2 l/min, 77 +/- 25 vs 79 +/- 24 mmHg; (3) 6 l/min, 125 +/- 43 vs 121 +/- 25 mmHg; (4) arterial pO(2) = 200 mmHg, 115 +/- 42 vs 144 +/- 23 mmHg; (5) arterial pO(2) = 300 mmHg, 145 +/- 41 vs 154 +/- 32 mmHg. In this pilot study, we could not identify significant differences in deltoid subcutaneous tissue oxygen pressure between lean and morbidly obese volunteers.

Effects of continuous remifentanil administration on intra‐operative subcutaneous tissue oxygen tension

Surgical stress response markedly increases sympathetic nerve activity and catecholamine concentrations. This may contribute to peripheral vasoconstriction, reduced wound perfusion and subsequent tissue hypoxia. Opioids are known to depress the hypothalamic-adrenal response to surgery in a dose-dependent manner. We tested the hypothesis that continuous remifentanil administration produces improved subcutaneous tissue oxygen tension compared to fentanyl bolus administration. Forty-six patients undergoing major abdominal surgery were randomly assigned to receive either fentanyl bolus administration or continuous remifentanil infusion. Mean subcutaneous tissue oxygen values over the entire intra-operative period were significantly higher in the remifentanil group, when compared to the fentanyl group: 8 (2) kPa vs 6.7 (1.5) kPa, % CI difference: - 2.3 kPa to - 0.3 kPa, p = 0.013. Continuous intra-operative opioid administration may blunt vasoconstriction caused by surgical stress and adrenergic responses more than an equi-effective anaesthetic regimen based on smaller-dose bolus opioid administration.

Perioperative fluid management: comparison of high, medium and low fluid volume on tissue oxygen pressure in the small bowel and colon

Insufficient blood flow and oxygenation in the intestinal tract is associated with increased incidence of postoperative complications after bowel surgery. High fluid volume administration may prevent occult regional hypoperfusion and intestinal tissue hypoxia. We tested the hypothesis that high intraoperative fluid volume administration increases intestinal wall tissue oxygen pressure during laparotomy. In all, 27 pigs were anaesthetized, ventilated and randomly assigned to one of the three treatment groups (n = 9 in each) receiving low (3 mL kg-1 h-1), medium (7 mL kg-1 h-1) or high (20 mL kg-1 h-1) fluid volume treatment with lactated Ringer's solution. All animals received 30% and 100% inspired oxygen in random order. Cardiac index was measured with thermodilution and tissue oxygen pressure with a micro-oximetry system in the jejunum and colon wall and subcutaneous tissue. Groups receiving low and medium fluid volume treatment had similar systemic haemodynamics. The high fluid volume group had significantly higher mean arterial pressure, cardiac index and subcutaneous tissue oxygenation. Tissue oxygen pressures in the jejunum and colon were comparable in all three groups. The three different fluid volume regimens tested did not affect tissue oxygen pressure in the jejunum and colon, suggesting efficient autoregulation of intestinal blood flow in healthy subjects undergoing uncomplicated abdominal surgery.