Oxygenation In Patients Research Articles

Evaluation of diagnostic and treatment approaches towards acute dyspnea in a palliative care setting among medical students at the University of Vienna

Dyspnea is common in advanced cancer patients with opioids as first line treatment. To evaluate the level of knowledge about diagnosis and treatment of dyspnea in palliative care patients among 4th year students. A case report was distributed to the students describing acute dyspnea in a lung cancer patient. Students were asked to rank their diagnosis and treatment options by importance. 633 medical students in their 4th year attended a seminar about palliative care. Of these, 423 (77%) completed the case report. The most frequent diagnostic option was measuring patient's oxygen saturation (n = 388), followed by auscultation (n = 339). As treatment options, students chose the delivery of oxygen (n = 393) as most important. The application of opioids was suggested by a total of 138 students. Although students did not have practical skills in treating advanced cancer patients with acute dyspnea, 32.6% would suggest an opioid as treatment option.

Endotracheal tube fire during tracheostomy

Endotracheal tube fire during tracheostomy

Evolving role of video laryngoscopy for airway management in the emergency department

Evolving role of video laryngoscopy for airway management in the emergency department

Intraoperative Pneumothorax Identified with Transthoracic Ultrasound

Intraoperative Pneumothorax Identified with Transthoracic Ultrasound

Use of Central Venous Oxygen Saturation to Guide Therapy

The use of pulmonary artery catheters has diminished, so that other technologies are emerging. Central venous oxygen saturation measurement (ScvO₂) as a surrogate for mixed venous oxygen saturation measurement (SvO₂) is simple and clinically accessible. To maximize the clinical utility of ScvO₂ (or SvO₂) measurement, it is useful to review what the measurement means in a physiologic context,how the measurement is made, important limitations, and how this measurement may be helpful in common clinical scenarios. Compared with cardiac output measurement, SvO₂ is more directly related to tissue oxygenation. Furthermore,when tissue oxygenation is a clinical concern, SvO₂ is less prone to error compared with cardiac output, where small measurement errors may lead to larger errors in interpreting adequacy of oxygen delivery. ScvO₂ should be measured from the tip of a central venous catheter placed close to, or within, the right atrium to reduce measurement error. Correct clinical interpretation of SvO₂, or its properly measured ScvO₂ surrogate, can be used to (1) estimate cardiac output using the Fick equation, (2) better understand whether a patient's oxygen delivery is adequate to meet their oxygen demands, (3) help guide clinical practice, particularly when resuscitating patients using validated early goal directed therapy treatment protocols, (4) understand and treat arterial hypoxemia, and (5) rapidly estimate shunt fraction (venous admixture).

Patient with Posterior Mediastinal Mass Requiring Urgent Cardiopulmonary Bypass

T HE literature on anesthetic concerns and perioperative care of patients with mediastinal masses has focused almost exclusively on anterior mediastinal masses. Posterior mediastinal masses traditionally have been suggested to carry a low risk of anesthetic implications. We present the case of a patient with a posterior mediastinal mass who experienced hemodynamic and respiratory decompensation upon induction of general anesthesia and required urgent transition to cardiopulmonary bypass (CPB). Our case illustrates the importance of real-time imaging provided by transesophageal echocardiography (TEE) in explaining the etiology of intractable hemodynamic instability and a new finding of significant pericardial and left pleural effusion not seen on preoperative imaging. TEE made clear the urgent need to initiate CPB because it revealed a near total compression of the left atrium, which was obstructing delivery of volume to the left ventricle. In addition, this case demonstrates the inadequacy of “stand-by” CPB and the need for every institution to establish an interdisciplinary team to develop, before surgery, a formal plan for the perioperative care of patients with mediastinal masses.

A novel strategy to improve systemic oxygenation in venovenous extracorporeal membrane oxygenation: The “χ-configuration”

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is used in refractory acute respiratory distress syndrome where lung recovery is the primary goal. For its achievement, adequate extracorporeal blood flow and a maximal separation between oxygenated (inflow) and deoxygenated (outflow) blood flow are essential for reducing the recirculation phenomenon. We introduce the χ-configuration, a new cannulation strategy for VV-ECMO. We report our experience with 30 VV-ECMO consecutive patients: in 16 patients (group NS) we applied the χ-configuration, which consists of a particular right atrial cannula arrangement and a self-made modified inflow cannula, consisting of an outflow multihole venous cannula that was inserted percutaneously through the right femoral vein, into the right atrium, just below on the superior vena cava, and a self-made modified curved inflow cannula (inserted percutaneously through the right internal jugular vein) that, in its terminal segment, permitted the tip to be positioned close to the tricuspid valve. In 14 patients (group C) we applied the standard femoro-jugular VV-ECMO 2-cannula setting. In both groups, efficacy of blood oxygenation was obtained by gas-blood analysis, by blood samples obtained at arterial, central venous, and pulmonary artery lines, and by ECMO inflow and outflow lines. The recirculation fraction was obtained by a specific bedside formula. No differences were noted between groups regarding the pre-ECMO patient characteristics. No complications during cannulation were recorded. In group NS, on-ECMO time, post-ECMO mechanical ventilation time, and ECMO overall results were significantly better than in group C. During high-flow VV-ECMO, pulmonary and systemic arterial oxygen saturation and arterial oxygen tension were significantly higher in group NS, and blood recirculation fraction was significantly lower. Our data indicate that χ-configuration can be safe, feasible, and more effective than conventional VV-ECMO. It permits near complete drainage of the desaturated blood and a preferential oxygenated blood inflow toward the tricuspid valve, resulting in a significant reduction of recirculation, thereby improving the patient's oxygenation. Our innovative strategy reduces on-ECMO and post-ECMO mechanical ventilation time, gives a faster and better pulmonary recovery, improves survival, and can reduce hospital costs.

Experience of Therapy for Pneumonia In Hematopoietic Stem Cell Transplant Recipients Infected by Influenza 2009 H1N1.

AbstractAbstract 4553In March 2009, a novel influenza H1N1 2009 virus was firstly detected in Mexico and then spread throughout the world rapidly. Till now, data about severe cases infected by 2009 H1N1 following allogeneic hematopoietic stem cell transplantation (allo-HSCT) are sparse, with only 11 anecdotal cases reported. We first describe three cases of influenza A/H1N1 2009 infection following allo-HSCT in China, including the first report in a haploidentical allo-HSCT recipient. The main clinical presentation in all cases are classic pneumonia-like symptoms and H1N1 virus was isolated from throat swabs in all patients. All patients received oral oseltamivir 75 mg twice a day, broad-spectrum antibiotic and anti-fungi drugs were given at the same time for co-infection. Two patients achieved complete resolution with this treatment regimen, the haploidentical HSCT recipient finally died of ARDS. Our cases suggest combination of oseltamivir, more effective of prophylaxis of co-infections and better supportive care is an effective treatment for influenza A/H1N1 2009 pneumonia in immunodeficient patients. The first case, a 16-year-old male, was diagnosed with acute lymphocytic leukemia (ALL-L2) in April 2008. He received HLA-identical sibling peripheral blood stem cells transplantation (allo-PBSCT) in October 23, 2008. Acute and chronic GVHD were not observed. He was admitted to our hospital for pharyngodynia, rhinobyon, exacerbated cough accompanied by pricked dyspnea on November 2009. Broad-spectrum antibiotic were administered for 3 days and no significant clinical improvement was observed. High-solution chest CT showed bilateral multiple flaky infiltrating. Influenza 2009 H1N1 virus was subtyped in his throat swab by real-time quantitative PCR (RT-PCR) analysis using validated CDC published primer/probe sets septic for variant 2009 H1N1 virus. The second case, a 25-year-old female, was diagnosed with acute lymphocytic leukemia (ALL-L2, B-cell, Ph-) in August 2008. She received HLA-identical unrelated donor (10/10 alleles matching) allo-PBSCT in April, 2009. She developed dermatosclerosis-like extensive cGVHD (skin) but the symptom was not improved after being treated with prednisone, thalidomide and tacrolimus. She was admitted to our hospital for palm infection in December, 2009. Chest CT showed lung infection and round lesion near the pleura. She was diagnosed with H1N1 influenza by RT-PCR analysis in throat swabs. The third case, a 42-year-old male, was diagnosed with acute lymphocytic leukemia (ALL-L2) with positive Bcr/Abl P190 fusion gene in October 2008. He received HLA-haploidentical sibling (his daughter) allo-PBSCT in April 2009. The patient developed grade II aGVHD (skin) on day 14 after transplantation, He achieved excellent response by being treated with prednisone and FK506. He was admitted to our hospital for skin rush and hyperglycemia in December, 2009. His oxygen saturation was 93.3% on room air. Chese CT showed interstitial ground glass-like changes in both lungs, and consolidation in both lobus inferior pulmonis. The patient developed progressive tachypnea after 4 days and was diagnosed with H1N1 influenza by RT-PCR analysis in throat swabs. All patients were nursed in H1N1-ICU ward for further treatment as soon as being diagnosed. Oseltamivir (75 mg twice a day) was given with broad-spectrum antibiotic and anti-fungi drugs. The first and second patients' symptoms were improved after 2 weeks, and recurrent throat swab examination was negative. The third patient was continued mechanical ventilation, Chest CT show infection was progressive and infiltrating in the whole lung. In January 7, 2010, the patient's oxygen saturation decreased to 50% and malignant ventricular arrhythmias were observed. Although with cardio pulmonary resuscitation for more than 1 hour, the patient died of ARDS. Our experience highlights on the severity of 2009 H1N1 infection in post-transplantation recipients. Haploidentical transplantation is an independent adverse prognostic factor. Oseltamivir is an effective therapy for pneumonia infected by 2009 H1N1, broad-spectrum antibiotic and anti-fungi drugs should be given at the same time. Disclosures:No relevant conflicts of interest to declare.

Case Scenario: Acute Postoperative Negative Pressure Pulmonary Edema

A 25-yr-old man (weight, 68 kg; height, 183 cm) presentedto the surgery center for excision of back and thigh schwan-nomas on the same day. The patient’s medical history wassignificant only for his history of multiple schwannoma re-sections and a history of smoking one pack of cigarettes perweek for the past 5 yr. He denied previous problems withgeneral anesthesia, and his baseline peripheral oxygen satu-ration was 99% on ambient air.Thepatientwaspremedicatedwith2mgmidazolam,andanesthesia was induced with 250 mg fentanyl, 500 mg thio-pental, and 8 mg vecuronium given for facilitation of tra-cheal intubation. He was atraumatically intubated with a7-mm ID endotracheal tube using a no. 3 Macintosh laryn-goscope (Teleflex Medical, Research Triangle Park, NC) onthe first attempt with direct visualization of the vocal cords.The patient was turned prone, bilateral breath sounds werereconfirmed, and schwannoma excisions were performed ontheleftthighandtheleftflank.Atotalof0.5mghydromor-phone was administered for analgesia. The intraoperativecoursewasunremarkable.Thepatientwashemodynamicallystable with minimal blood loss and was easily ventilated andoxygenated. A total of 500 ml lactated Ringer’s solution wasadministeredduringthe65-minsurgicalprocedure.Thepa-

Factors leading to self‐extubation of endotracheal tubes in the intensive care unit

To discuss the factors leading to self-extubation of endotracheal tubes (ETTs) and explore the differences between the groups of patients who did and did not self-remove their ETTs. Self-extubation of ETTs has been reported to occur in 4.2% of severely ill patients and is associated with adverse medical effects. A case-control study. One hundred and thirty-nine subjects were recruited from a teaching hospital in southern Taiwan based on purposive sampling. The rate of self-extubation of ETTs was 6.4%. Analysis of the two groups demonstrated that significant variables were identified and fell into three categories: (1) the department to which the patient was admitted (p < 0.001), (2) whether the patient met the criteria for extubation (p < 0.001) and (3) the patient age (p < 0.05). Based on multiple logistic regression analysis, whether the patient met the criteria for extubation was a main variable that was associated with self-extubation of the ETT. Among the 44 patients who had self-extubation of their ETT, 28 met the criteria to be extubated, 70% and 81.8% of whom were not sedated, and self-extubation of their ETT was conscious of the act. Of the patients who attempted to self-remove their ETT, 80% were successful and 93.2% did not incur any adverse medical effects. The medical doctor and nurse should fully evaluate a patient's oxygenation status, decrease the length of the extubation training session for patients and extubate patients promptly when extubation criteria are met. Adopting a proactive approach to patient extubation will improve the overall quality of care.

Clinical and statistical evaluation of 1st Automatic: a pilot study.

Arterial blood gas analyses provide information about the patient's oxygenation, ventilation, and perfusion. Studies have shown that most errors occur during the pre-analytical phase (the processes prior to the actual analysis of the sample). 1st Automatic is an extra module to the existing blood gas analyzer and a partial automation of the pre-analytical phase which is designed to reduce these errors. The objective was to investigate whether 1st Automatic is compatible to the conventional method. Quantitative measurements of pH, pCO2, pO2, Na+, K+, Ca2+, cGlu, cLac and tHb were performed on 21 paired whole blood specimens collected into the standard blood gas syringes and safePICO syringes, both designed for the ABL800 FLEX. During the collection the pre-analytical errors were minimised. No clinically significant differences were observed in the nine blood gas parameters. The differences were statistically insignificant, with the exception of cNa+, cCa2+ and tHb. There was a good consistency between the results using the new automated procedure and the conventional method. It was not possible to show any clinically significant difference between the two procedures.

Flex: A New Computerized System for Mechanical Ventilation

To describe and evaluate a new weaning and decision support system for mechanical ventilation. FLEX is a computerized weaning and decision support system for mechanical ventilation that unlike previous rule-based systems derives many of its rules on the basis of the conditions of individual patients. This system can be used in a wide range of ventilatory modes as well as automatic control of weaning. It incorporates the features of the patented ventilatory mode known as Adaptive Support Ventilation (ASV) along with other new features for control of weaning, and control of patient's oxygenation by adjustment of PEEP and the fraction of inspired oxygen. Ventilator data was collected for 10 patients in medical/surgical ICU at baseline and about 24 hours later. Required data fields for each patient for these two time points were also entered into the FLEX program. Comparison of clinical data and FLEX recommendations were made with regard to minute ventilation, alarms, weaning institution and other variables. At baseline, 7 patients were being treated with AC, the remainder with IMV/PS. There was good agreement between the measured and recommended minute ventilations; variances were seen in some patients being treated with permissive hypercapnea and those with evidence of high oxygen needs or other metabolic derangements. At 24 hours, there was improved correlation between measured minute ventilation and that recommended by FLEX, suggesting that clinical adjustments were in-line with Flex recommendations over time. Furthermore, FLEX made recommendations with regard to FIO(2) and PEEP that would potentially diminish the risk of oxygen toxicity, hypoxemia, and barotrauma in selected patients. FLEX has also been implemented as a closed loop system in an initial set up. A new weaning and decision support system for mechanical ventilation is presented. The recommendations made by the system were found to be in line with clinical determinations. Further refinements in the FLEX predictions can be easily made by including inputs which represent permissive hypercapnea or increased metabolic demand for selected patients.

Pressure-support Ventilation in the Operating Room

We appreciate Dr. Feldman's comments on our editorial.1Before extubating patients in the operating room, the anesthesiologist typically evaluates the patient's respiratory effort, tidal volume, and respiratory rate, as well as the patient's oxygen saturation and carbon dioxide elimination. To compensate for the difficulties of breathing through an endotracheal tube and the breathing circuit, we frequently apply continuous positive airway pressure using the adjustable pressure-limiting valve on the anesthesia machine. Knowing that continuous positive airway pressure is functionally a combination of pressure-support ventilation and positive end-expiratory pressure, the level of support is typically minimal. If the level of support were significant, the patient could be falsely judged as ready for extubation. At the conclusion of the procedure, the adjustable pressure-limiting valve is usually fully opened so that the patient's respiratory performance can be evaluated with zero support. If the pressure-support ventilation mode is used until the patient is extubated, we think that the anesthesiologist may get a false sense of security regarding the patient's readiness for extubation. Although this is a common practice in the intensive care unit, we are not sure whether the same practice applies to the operating room. Patients in the operating room temporarily have an acute change in their respiratory status, whereas intensive care unit patients have a more prolonged weaning period before extubation.Although using the pressure-support ventilation mode with the ventilator in the operating room may be new for some anesthesiologists, anesthesiology residents are familiar with it from their training in the intensive care unit. We think that it is important to emphasize to our residents the need to first look at the patient and do a clinical assessment before relying on mechanical devices. Therefore, the question is still whether there is enough benefit to the patient to justify the increase in cost to add the pressure-support ventilation mode.*Yale University, School of Medicine, New Haven, Connecticut. jan.ehrenwerth@yale.edu

In Vivo Validation of the M-COVX® Metabolic Monitor in Patients under Anaesthesia

A practical method of breath-by-breath monitoring of metabolic gas exchange has been developed by GE Healthcare/Datex Ohmeda and incorporated into existing anaesthetic and critical care monitoring systems (M-COVXO). This device relates flow measurements made at the mouth by pneumotachograph to measurements of inspired and expired gas composition by matching the two waveforms thereby allowing continuous, breath-by-breath monitoring of an intubated patient's oxygen uptake and carbon dioxide production. Given that there is a paucity of data comparing this new device against methods more widely used clinically, we tested the device on 11 patients undergoing cardiopulmonary bypass surgery. Using a standard anaesthetic machine (Datex Ohmeda Excel 210 SE) with a semi-closed circle absorber system, oxygen uptake was measured at the mouth continuously throughout the operation at approximately six-second intervals. The data were compared against the reverse Fick method and against standard indirect calorimetry using the Haldane transformation. When compared to the calculated reverse Fick oxygen uptake, a mean difference of +16.5% was found pre-bypass and +9.9% post-bypass, consistent with uptake of oxygen by lung tissue, which is not taken into account by the reverse Fick method. Measurements made comparing the M-COVX metabolic monitor against standard Haldane showed a mean difference of +5.1% pre-bypass and -2.1% post-bypass. Given the ease with which this device can be incorporated into existing anaesthetic monitoring systems and its accuracy in measuring oxygen uptake, the M-COTVX module is an attractive addition to existing perioperative monitoring.

Acute Respiratory Distress following Liposuction

An active duty male presented to the emergency room with dyspnea for 2 days after undergoing liposuction surgery. Upon presentation, the patient was afebrile, tachycardic, tachypneic, and hypoxemic. The initial chest radiograph demonstrated bilateral patchy opacities and the PaO2/FiO2 ratio was <200. The patient was admitted to the medical intensive care unit for supportive care. He was treated empirically for pneumonia. Blood and sputum cultures were negative. A computed tomography angiogram of the chest was negative for pulmonary embolism but did reveal a bilateral, perihilar air space process. The patient's oxygen requirement improved and the abnormal chest radiographic findings resolved over the next 48 hours. Given his clinical presentation, negative workup, and rapid recovery, the patient was given a presumptive diagnosis of pulmonary fat embolism. Fat embolism occurs when adipocytes and small blood vessels are damaged during the liposuction procedure. Patients may present with low-grade fever, tachycardia, tachypnea, hypoxemia, and hypocapnia. The differential diagnosis includes venous thromboembolism, aspiration pneumonitis, and pneumonia. The mainstay of treatment for pulmonary fat embolism is supportive care. The risk of mortality is 5 to 15%.

Successful treatment with one-way endobronchial valve of large air-leakage complicating narrow-bore enteral feeding tube malposition

Tracheopulmonary intubation is the most common misplacement site for narrow-bore feeding tube and it might be associated with severe pleuro-pulmonary complications. A 38-year-old female with a severe bilateral pneumonia and acute respiratory insufficiency was admitted in the ICU, intubated, and mechanically ventilated. Few hours after the insertion of a narrow-bore feeding tube the patient's oxygen saturation dropped with hypotension and tachycardia. A large left-side hydropneumothorax developed requiring a chest tube. Air-leakage was important and bronchoscopic implant of one-way endobronchial valve was accomplished. Immediate and substantial decrease of air-leakage was observed, and it completely stopped after 5 days; as soon as the patient was extubated. Endobrochial one-way valve, specifically designed for bronchoscopic lung volume reduction, resulted in being safe and effective to control a significant and prolonged air-leakage due to a malposition of a narrow-bore feeding tube.

Independent Lung Ventilation in the Management of Traumatic Bronchopleural Fistula

Independent lung ventilation (ILV) is a technique for managing patients with unilateral lung disease or injury who have failed conventional mechanical ventilation. A 20-year-old man sustained severe ballistic injuries to the chest and abdomen. Damage control laparotomy controlled the patient's initial hemorrhage, however, an evolving cavitary pulmonary lesion subsequently developed into a high-volume bronchopleural fistula. Progressive atelectasis of the damaged lung resulted in profound hypoxemia and hypercarbia refractory to conventional mechanical ventilation. Synchronous ILV was initiated using a double-lumen endotracheal tube and two ventilators titrated to optimize the patient's oxygenation and ventilation and minimize ventilator-induced lung injury. Intensive ILV over the next 17 days resulted in recruitment of the atelectatic right lung, resolution of the bronchopleural fistula, and significant improvement in oxygenation and pulmonary compliance. This appears to be the longest reported use of ILV for traumatic lung injury.

Supplemental Perioperative Oxygen and the Risk of Surgical Wound Infection: A Randomized Controlled Trial

ABSTRACT Three hundred patients were enrolled in a double-blind, randomized, controlled study designed to investigate the ability of supplemental perioperative oxygen to reduce wound infection. Participants were age 18 to 80 years, had no coexisting serious medical conditions, and were scheduled to undergo elective colorectal surgery at one of 14 participating hospitals in Spain. No patients undergoing minor or laparoscopic surgery were included. Anesthesia and antibiotic prophylaxis were standardized for the study. Patients were randomized by computer-generated codes to receive an oxygen/air mixture of 30% or 80% fraction of inspired oxygen (F102) intraoperatively and postoperatively for 6 hours. After 6 hours, oxygen was given only in amounts needed to maintain 92% saturation. Postoperative care was determined by the attending surgeon who was unaware of the patient's oxygen group. Wounds were inspected daily and surgical site infections (SSI) were diagnosed according to the definitions of the Centers for Disease Control and Prevention. Infections occurring during the first 14 days were considered for analysis. Nine patients did not meet inclusion criteria. Of the remaining 291 patients, 143 received 30% and 148 received 80% oxygen. The 2 groups were similar in clinical characteristics, including preoperative laboratory studies and risk of infection score. Surgical characteristics, including length of operative procedure, blood loss, and transfusion rate, were also similar between the 2 groups. Fifty-seven patients (19.3%) developed a wound infection. The incidence of wound infection was 35 of 143 (24%) in the 30% F102 group and 22 of 148 (14.9%) in the 80% F102 patients (P = 0.04). The risk of SSI was 39% lower in the high oxygen group compared with those who received less oxygen (relative risk, 0.61; 95% confidence interval [CI], 0.38–0.98). Other measures of surgical outcome, including return of bowel function, ability to tolerate solid food, ambulation, suture removal, and duration of hospitalization, were not significantly different for the 2 treatment groups. When patients who developed wound infections were compared with those without infection, the group with SSI had a longer time to ambulation (mean, 4.9 vs 3.9 days; P = 0.008), a longer time to staple removal (11.6 vs 10.1 days; P = 0.007), and were in the hospital longer (15.1 vs 10.7 days; P = 0.001). Two patients, both in the 30% oxygen group, died of sepsis during the study period. After multivariate analysis of possible confounding variables, the relative risk of wound infection in patients who received 80% oxygen was 0.46 (95% CI, 0.22–0.95; P = 0.04) compared with those who received 30% oxygen.

Silicone Pneumonitis after a Cosmetic Augmentation Procedure

To the Editor: The injection of silicone for cosmetic procedures is common practice in the United States. We describe a case of severe silicone-induced pneumonitis leading to respiratory failure. A previously healthy 30-year-old woman presented with progressive cough and shortness of breath of 10 days' duration. For cosmetic augmentation, an unlicensed nurse had given the patient two silicone injections into her buttocks 12 days and 2 days before admission. At the initial evaluation, the patient's oxygen saturation was 63 percent while she was breathing ambient air; her pulse was 119 beats per minute, blood pressure 98/66 mm Hg, respiratory rate . . .

Efficacy of Measuring Oxygen Extraction Ratio for Determination of Intraoperative Red Blood Cell Transfusion in a Case with Chronic Normovolemic Anemia

Allogeneic red blood cell transfusion should not be dictated, unless the patient's oxygen-carrying capacity is decompensated, and the signs and symptoms requiring blood transfusion have been observed. In cases with chronic normovolemic anemia, an increase of 2, 3-DPG compensates the patient's oxygen delivery capacity by leading the hemoglobin-oxygen dissociation curve shift to right, thereby allowing the unloading of a normal oxygen amount with a lower concentration of hemoglobin, which makes it difficult to assess the appropriate timing for red blood cell transfusion. Here, we describe the efficacy of measuring the oxygen extraction ratio in such a case.