A comprehensive neuromonitoring approach in a large animal model of cardiac arrest.

BACKGROUND: Anoxic brain injuries represent the main determinant of poor outcome after cardiac arrest (CA). Large animal models have been described to investigate new treatments during CA and post-resuscitation phase, but a detailed model that includes extensive neuromonitoring is lacking. METHOD: Before an electrically-induced 10-minute CA and resuscitation, 46 adult pigs underwent neurosurgery for placement of a multifunctional probe (intracranial pressure or ICP, tissue oxygen tension or PbtO2 and cerebral temperature) and a bolt-based technique for the placement and securing of a regional blood flow probe and two sEEG electrodes; two modified cerebral microdialysis (CMD) probes were also inserted in the frontal lobes and accidental misplacement was prevented using a perforated head support. RESULT: 42 animals underwent the CA procedure and 41 achieved the return of spontaneous circulation (ROSC). In 4 cases (8.6%) an adverse event took place during preparation, but only in two cases (4.3%) this was related to the neurosurgery. In 6 animals (13.3%) the minor complications that occurred resolved after probe repositioning. CONCLUSION: Herein we provide a detailed comprehensive neuromonitoring approach in a large animal model of CA that might help future research.

PCO2 gap, its ratio to arteriovenous oxygen content, ScvO2 and lactate in high-risk abdominal surgery patients: An observational study.

BACKGROUND: The difference between arterial and central venous carbon dioxide partial pressure (PCO2 gap), a marker of oxygen delivery (DO2) and oxygen consumption (VO2) adequacy, has been evaluated as a promising prognostic tool in intensive care unit (ICU) patients. We therefore sought to study the association between intraoperative PCO2 gap and postoperative complications (POC) in the perioperative setting of elective major abdominal surgery. METHODS: We conducted a single-centre prospective observational study. All adult patients who underwent major planned abdominal surgery were eligible. PCO2 gap was measured every 2 h during surgery, at ICU admission and repeated 12 h and 24 h later. Severe POC within 28 days after surgery were defined as complications graded 3 or more according to Clavien-Dindo classification. Following a univariate analysis, a multivariable analysis using a logistic regression model was performed. RESULTS: Ninety patients were included and divided into two groups according to the occurrence of POC. No significant difference was found between groups regarding baseline characteristics at inclusion. Thirty-nine (43%) patients developed postoperative complications. The median [IQR] intraoperative PCO2 gap was significantly higher in patients who had complications (6.5 [5.5-7.3] mmHg) compared to those who did not (5.0 [3.9-5.8] mmHg; p < 0.001). The area under the receiver operating characteristic curve for occurrence of POC was 0.78 for the PCO2 gap. After multivariable analysis, PCO2 gap was found independently associated with POC (OR: 14.9, 95% CI [4.68-60.1], p < 0.001) with a threshold value of 6.2 mmHg. The duration of surgery (OR: 1.01, 95% CI [1.00; 1.01], p = 0.04) and the need for vasoactive support during surgery (OR: 5.76, 95% CI [1.72; 24.1], p = 0.006) were also independently associated with POC. CONCLUSION: Intraoperative PCO2 gap is a relevant predictive factor of severe postoperative complications in high-risk elective surgery patients. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03914976.

Racial discrepancy in pulse oximeter accuracy in preterm infants.

OBJECTIVE: Pulse oximetry is commonly used in Neonatology, however recent adult data suggest racial disparity in accuracy, with overestimation of oxygen saturation for Black patients. STUDY DESIGN: Black and White infants <32 weeks gestation underwent simultaneous arterial blood gas and pulse oximetry measurement. Error by race was examined using mean bias, Arms, Bland-Altman, and linear/non-linear analysis. RESULTS: A total of 294 infants (124 Black, 170 White) were identified with mean GA of 25.8 ± 2.1 weeks and mean BW of 845 ± 265 grams, yielding 4387 SaO2-SpO2 datapoints. SpO2 overestimation, measured by mean bias, was 2.4-fold greater for Black infants and resulted in greater occult hypoxemia (SpO2 > 90% when SaO2 < 85%; 9.2% vs. 7.7% of samples). Sensitivity and specificity for detection of true hypoxemia were similar between groups (39 vs. 38%; 81 vs. 78%). CONCLUSION: There is a modest but consistent difference in SpO2 error between Black and White infants, with increased incidence of occult hypoxemia in Black infants.

Unnecessary harm is avoided by reliable paediatric index of mortality2 scores without arterial gas sampling.

AIM: To investigate whether unnecessary harm could be avoided in children admitted to paediatric intensive care (PICU), we analysed the impact of arterial blood gas on the paediatric index of mortality score2 (PIM2) and the derived predicted death rate (PDR). METHODS: From January 1, 2008 to December 31, 2010, 1793 consecutive admissions, newborn infants to 16 years of age (median 0.71 years) from a single, tertiary PICU in Gothenburg Sweden, were collected. Admission information on arterial oxygen tension (PaO2 ) and fraction of inspired oxygen (FiO2 ) was extracted from 990 admissions. RESULTS: There was close agreement between PIM2 score and PDR regardless of whether the PaO2 /FiO2 ratio was omitted or not. In the subgroup of admissions with a respiratory admission diagnosis, the inclusion of the PaO2 /FiO2 ratio increased the accuracy of the PIM2 score as well as the PDR. The standard mortality ratio was slightly but not significantly overestimated by excluding the PaO2 /FiO2 ratio. CONCLUSION: To avoid unnecessary harm to children admitted to PICU, an arterial blood gas analysis should only be performed if clinically indicated or if the child has a respiratory admission diagnosis. Estimation of the PIM2 score and PDR will not be less accurate by this approach.

Vapocoolant Spray Effectiveness on Arterial Puncture Pain: A Randomized Controlled Clinical Trial.

Arterial blood gas (ABG) sampling is a painful procedure with no perfect technique for quelling the discomfort. An ideal local anesthesia should be rapid, easy to learn, inexpensive, and noninvasive. This study was aimed to compare pain levels from ABG sampling performed with vapocoolant spray in comparison to placebo. We hypothesized that pretreatment with the vapocoolant would reduce the pain of arterial puncture by at least 1 point on a 10 point verbal numeric scale. We have evaluated the effectiveness of a vapocoolant spray in achieving satisfactory pain control in patients undergoing ABG sampling in this randomized placebo controlled trial. Eighty patients were randomized to 2 groups: group A, who received vapocoolant spray, and group B, who received water spray as placebo (Control group). Puncture and spray application pain was assessed with numerical rating scale (0, the absence of pain; 10, greatest imaginable pain) and number of attempts was recorded. The pain score during ABG sampling was not lower in group A compared with group B significantly (4.78±1.761 vs. 4.90±1.837; P:0.945). This study showed that while the spray exerts more application pain, the number of attempts required for ABG sampling was not significantly lower in group A compared with group B (1.38±0.54 vs. 1.53±0.68; P=0.372). Vapocoolant spray was not effective in ABG pain reduction, had milder application pain compared to placebo (P<0.05), but did not reduce sampling attempts. At present, this spray cannot be recommended for arterial puncture anesthesia, and further study on different timing is necessary.

Safety of the CO-Rebreathing Method in Patients with Coronary Artery Disease.

PURPOSE: To address and study the safety concerns with the improved carbon monoxide (CO) rebreathing method for measuring total blood volume in patients with coronary artery disease to implement the use of the methodology in this patient group. METHODS: Eighteen patients with stable coronary artery disease (age 62 ± 7 yr, 24 ± 5 months since diagnosis) were investigated using the improved CO-rebreathing test. Before, during, and up to 2 h after the test, ECG, blood pressure, arterial oxygen saturation, carbon monoxide bound to hemoglobin (HbCO%), and cardiac function were measured. At 24 h, HbCO% and troponin-T were measured. DESIGN: Cross-over. RESULTS: Six minutes after the CO-rebreathing test, HbCO increased from 1.5% ± 0.4% to 6.0% ± 0.6%, with a subsequent decrease to 4.5% ± 0.4% and 1.4% ± 0.4% at 2 h and 24 h after the test, respectively. Resting heart rate, stroke volume, cardiac output, and ejection fraction were 64 ± 11 bpm, 93.9 ± 16.5 mL per beat, 5.84 ± 0.99 L, and 48.5% ± 5.7% and remained unchanged during and 10 min after the rebreathing. All patients were in sinus rhythm during the 2-h observation period, without ST- or T-wave changes, with low numbers of premature beats and normal rate variability. Systolic and diastolic blood pressure gradually decreased during the observation period. Troponin-T was below the 99th percentile for all the participants 24 h after the test. CONCLUSION: Cardiovascular function and safety indices remained unchanged after exposure to approximately 6% HbCO, indicating that the method is safe to perform in patients with stable coronary artery disease.

A rate-based transcutaneous CO2 sensor for noninvasive respiration monitoring.

The pain and risk of infection associated with invasive blood sampling for blood gas measurements necessitate the search for reliable noninvasive techniques. In this work we developed a novel rate-based noninvasive method for a safe and fast assessment of respiratory status. A small sampler was built to collect the gases diffusing out of the skin. It was connected to a CO2 sensor through gas-impermeable tubing. During a measurement, the CO2 initially present in the sampler was first removed by purging it with nitrogen. The gases in the system were then recirculated between the sampler and the CO2 sensor, and the CO2 diffusion rate into the sampler was measured. Because the measurement is based on the initial transcutaneous diffusion rate, reaching mass transfer equilibrium and heating the skin is no longer required, thus, making it much faster and safer than traditional method. A series of designed experiments were performed to analyze the effect of the measurement parameters such as sampler size, measurement location, subject positions, and movement. After the factor analysis tests, the prototype was sent to a level IV NICU for clinical trial. The results show that the measured initial rate of increase in CO2 partial pressure is linearly correlated with the corresponding arterial blood gas measurements. The new approach can be used as a trending tool, making frequent blood sampling unnecessary for respiratory status monitoring.

Reevaluation of the utilization of arterial blood gas analysis in the Intensive Care Unit: effects on patient safety and patient outcome.

PURPOSE: Arterial blood gas (ABG) analysis is a useful tool to evaluate hypercapnia in the context of conditions and diseases affecting the lungs. Oftentimes, indications for ABG analysis are broad and nonspecific and lead to frequent testing without test results influencing patient management. MATERIALS AND METHODS: Electronic charts of 300 intensive care unit (ICU) patients at a single institution were reviewed retrospectively. Reassessment of indications for ABGs led to a decrease of the number of ABGs in the ICU between March and November 2012. Data relating to ventilator days, length of stay, number of reintubations, mortality, complications after arterial puncture, demographics, and medications in 159 ICU patients between December 2011 and February 2012 (group 1) were compared with 141 ICU patients between December 2012 and February 2013 (group 2). Subgroup analysis in ventilated patients was performed. RESULTS: A decrease of number of ABGs per patient (6.12 ± 5.9, group 1 vs 2.03 ± 1.66, group 2 in ventilated patients; P = .007) was found along with a decrease in the number of ventilator days per patient (P = .004) and a shorter length of stay for ventilated patients in group 2 compared with group 1 (P = .04). CONCLUSION: A significant decrease of ABGs obtained in the ICU does not negatively impact patient outcome and safety. A decrease in the number of ABGs per patient allows cost-efficient patient care with a lower risk for complications.

Less painful arterial blood gas sampling using jet injection of 2% lidocaine: a randomized controlled clinical trial.

OBJECTIVE: The aim of this study was to compare pain levels from arterial blood gas (ABG) sampling performed with or without application of lidocaine via jet injector. BACKGROUND: Pain is still a primary concern in the emergency department. Arterial blood gas sampling is a very painful procedure. No better technique for decreasing the pain of the ABG procedure has been presented. An ideal local anesthesia procedure for ABG sampling should be rapid, easily learned, inexpensive, and free of needlestick risk. MATERIALS AND METHODS: We evaluated the effectiveness of a lidocaine jet injection technique in achieving satisfactory pain control in patients undergoing ABG sampling. Forty-two patients were randomized to 2 groups: group A, which received lidocaine by jet injection (0.2 mL of lidocaine 2%), and group B, a control group that received a topical application of 1 mL of lidocaine gel 2% 2 minutes before the ABG sampling. Pain was assessed on a 10-cm visual analog scale (0, absence of pain; 10, greatest imaginable pain). RESULTS: The pain visual analog scale score during ABG sampling was considerably lower in group A compared with group B (1.29 ± 0.90 vs 4.19 ± 1.43; P < .001). The number of attempts required for ABG sampling was significantly lower in group A compared with group B (1.29 ± 0.46 vs 2.1 ± 0.12; P = .009). All residents reported ease of use with the lidocaine jet injection procedure (P < .05). CONCLUSION: Lidocaine jet injection provides beneficial and rapid anesthesia, resulting in less pain and a greater rate of successful ABG sampling. Therefore, it is recommended for use before ABG sampling to decrease the patient's pain and the number of unsuccessful attempts and to enhance the patient's satisfaction.

Diabetic ketoacidosis: difference between potassium determined by blood gas analysis versus plasma measurement.

OBJECTIVE: To evaluate the accuracy of potassium concentrations measured by blood gas analysis (PBG) compared with laboratory serum potassium (LSP), in the initial care of patients with diabetic ketoacidosis (DKA). SUBJECTS AND METHODS: Fifty three patients with diabetes mellitus were evaluated in a retrospective analysis. PBG was carried out using the Radiometer ABL 700 (Radiometer Copenhagen(®)), and results were compared with LSP ADVIA 1650 Chemistry system (Siemens(®)), the gold standard method. Both methods are based on potentiometry. RESULTS: Mean PBG was 3.66 mmol/L and mean LSP was 4.79 mmol/L. Mean difference between PBG and LSP was -1.13 mmol/L (p < 0.0005, 95% CI, -1.39 to -0,86). Lin concordance correlation coefficient was rc = 0.28 (95% CIb, 0.10 to 0.45), demonstrating low concordance between the methods. CONCLUSION: Although PBG measurement is faster and easier, it should not be used as a surrogate for LSP in the clinical treatment of DKA.

Diabetic ketoacidosis: difference between potassium determined by blood gas analysis versus plasma measurement / Cetoacidose diabética: diferença entre as concentrações do potássio na gasometria sanguínea versus potássio plasmático

OBJECTIVE: To evaluate the accuracy of potassium concentrations measured by blood gas analysis (PBG) compared with laboratory serum potassium (LSP), in the initial care of patients with diabetic ketoacidosis (DKA). SUBJECTS AND METHODS: Fifty three patients with diabetes mellitus were evaluated in a retrospective analysis. PBG was carried out using the Radiometer ABL 700 (Radiometer Copenhagen®), and results were compared with LSP ADVIA 1650 Chemistry system (Siemens®), the gold standard method. Both methods are based on potentiometry. RESULTS: Mean PBG was 3.66 mmol/L and mean LSP was 4.79 mmol/L. Mean difference between PBG and LSP was -1.13 mmol/L (p < 0.0005, 95 percent CI, -1.39 to -0,86). Lin concordance correlation coefficient was rc = 0.28 (95 percent CIb, 0.10 to 0.45), demonstrating low concordance between the methods. CONCLUSION: Although PBG measurement is faster and easier, it should not be used as a surrogate for LSP in the clinical treatment of DKA.

OBJETIVO: Avaliar a acurácia da mensuração da concentração de potássio realizado nos analisa-dores de gasometria sanguínea (PGS) em relação ao potássio plasmático laboratorial (PPL) no atendimento inicial dos pacientes com cetoacidose diabética (CAD). SUJEITOS E MÉTODOS: Foram avaliados, retrospectivamente, 53 pacientes com diabetes melito e CAD. A análise do PGS foi realizada pelo equipamento ABL 700 (Radiometer Copenhagen®), sendo este comparado ao método padrão-ouro de PPL ADVIA 1650 (Siemens®), ambos por potenciometria. RESULTADOS: A média do PGS foi de 3,66 mmol/L e do PPL, de 4,79 mmol/L. A diferença das médias do PGS em relação ao PPL foi de -1,13 mmol/L (p < 0,0005, IC = 95 por cento; -1,39 a -0,86). O coeficiente de concordância de Lin foi de rc = 0,28 (ICb = 95 por cento; 0,10 a 0,45), demonstrando, assim, uma baixa concordância entre os métodos. CONCLUSÃO: Apesar de a realização do PGS ser tecnicamente mais rápida e fácil, não deve ser usada como parâmetro substituto ao PPL para o tratamento clínico da CAD.

Hemorragia grave de la arteria radial secundaria a punción para gasometría en un insuficiente renal en tratamiento con antiagregantes / No disponible

No disponible

Efeito da refrigeração sobre o exame hemogasométrico em sangue venoso de ovinos / Effect of refrigeration on the hemogasometric examination of venous blood in sheep

Com o propósito de avaliar o efeito da refrigeração sobre o exame hemogasométrico, foram utilizados 12 ovinos machos, hígidos, da raça Santa Inês, com cerca de quatro meses de idade e peso variando entre 30 e 45 kg. As amostras de sangue destinadas ao exame hemogasométrico foram coletadas em duplicata utilizando-se agulhas descartáveis acopladas à seringas plásticas contendo cerca de 1000UI de heparina sódica. Durante e após a coleta tomou-se o cuidado de evitar a entrada de bolhas de ar no interior da seringa. As amostras não conservadas foram mantidas a temperatura ambiente, entre 23 e 25°C, e aquelas destinadas à refrigeração foram acondicionadas em isopor contendo 3kg de água gelada e 3kg de gelo, mantendo-se assim uma temperatura entre 0 e 4° C. As análises hemogasométricas foram determinadas imediatamente após coleta e com 1, 2, 3, 4, 5, 6, 8, 10, 12 e 24 horas. As análises dos resultados indicaram alterações significativas nas amostras mantidas a temperatura ambiente, caracterizado-se por diminuições, a partir da 4, 8 e 10 horas após coleta, para os valores do pH, BE e StB, respectivamente, e por aumento, a partir da 6 hora, para os valores da PCO(2 subscrito).Com relação as amostras conservadas, não foram evidenciadas variações significativas dos parâmetros ao longo dos tempos de análise. Conclui-se, portanto, que amostras de sangue venoso de ovinos são viáveis, para a realização do exame hemogasométrico, até 24 horas após coleta, desde que mantidas sob adequada refrigeração.

With the objective of evaluating the effect of refrigeration on the hemogasometric exam, venous blood samples were collected from 12 healthy male sheep, Santa Ines breed, with a mean age of 4 months old, and body weight raging from 30 to 45 kg. The blood samples for the hemogasometric examination were collected in two aliquots from each animal, using dispensable needles connected to plastic syringes containing about 1000 IU sodium heparin. During and after the sampling, the care of avoiding the presence of air bubbles in the syringe was attempted. The samples without conservation were kept at room temperature, between 23 an 25°C, and the samples under refrigeration were kept in an box containing 3 L of cold water and 3Kg of ice, to maintain a temperature between 0 and 4°C. The hemogasometric analyses were made immediate1y after collection an after 1, 2, 3, 4, 5, 6, 8, 10, 12 and 24 hours. The results indicated significant alteration in samples kept at room temperature, characterized by decline, starting at 4, 8 and 10 hour post-collection, of the values f pH, BE and StB, respectivelly, and by a raise, since the 6th hour, of the values of PCO(2subscript). No significant variations of the parameters were seen in the refrigerated samples during the study. So, the conclusion is that ovine venous blood samples are viable, for the determination of the hemogasometric evaluation, until 24 hours after the collection, when kept (maintained) under adequate refrigeration.

[Full version of the 2005 Standards, Options and Recommendations for the management of procedure-related pain (lumbar puncture, bone marrow aspiration or biopsy, blood sampling) in adult patients with cancer]. / Recommandations pour la pratique clinique 2005 : Standards, Options et Recommandations pour la prise en charge des douleurs provoquées lors des ponctions lombaires, osseuses et sanguines chez l'adulte atteint de cancer (rapport intégral) ,Validation du rapport original : janvier 2005.

The << Standards, Options and Recommendations >> (SOR) project, started in 1993, is a collaboration between the Federation of French Cancer Centres (FNCLCC), the 20 French cancer centres, and specialists from French public universities, general hospitals and private clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and the outcome of cancer patients. The methodology is based on a literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. Objectives : To establish the Standards, Options and Recommendations clinical practice guidelines for the management of procedure related pain (lumbar puncture, bone marrow aspiration or biopsy, blood sampling) in adult oncology patients. To define, on the basis of the critical appraisal of the best available evidence and expert agreement, the clinical situations in which a pain preventive strategy should be implemented. Methods. Medline(R) was searched using specific search strategies from January 1966 to August 2003. Literature monitoring was performed to identify controlled clinical trials published between August 2003 to September 2004. In addition several Internet sites were searched in July 2003. Results. A total of 12 references, corresponding to 10 randomised clinical trials, were identified. Clinical guidelines have been defined for each invasive procedure.

Local anaesthesia for venous cannulation and arterial blood gas sampling: are doctors using it?

The pain of venous cannulation and arterial puncture can be greatly lessened by local anaesthesia. We sought information about the use of local anaesthesia for these procedures by doctors working in medicine, surgery and anaesthetics. A questionnaire was hand-delivered to 178 doctors in eight hospitals, all of whom responded. For insertion of large-bore cannulae, local anaesthesia was used by all the anaesthetists but less than half the medical and surgical doctors. For arterial blood sampling it was used by 60% of anaesthetists and 2% of ward doctors. Previous recommendations to use local anaesthesia seem to have been ignored, and in many instances these procedures are more painful than necessary.

An audit of the patient's experience of arterial blood gas testing.

Arterial puncture is the most common method used to obtain a sample for the measurement of arterial blood gases (ABGs) and is essential to guide the prescription of long-term oxygen therapy (LTOT) in patients with chronic hypoxic lung disease. However, this procedure is often reported by patients as a painful and unpleasant experience, which to date has not been explored. This audit specifically examines the subjective views of a small group of patients (n = 41) who are receiving LTOT who have experienced repeated ABGs. Results demonstrated that 49% (n = 20) were poorly informed regarding what the procedure involved, almost half the patients 49% (n = 20) recalled pain levels of 5 and above on a visual analogue scale and 66% (n = 27) were totally unaware that the test could make a considerable difference to their treatment. While highlighting the deficits in current practice locally, this audit concludes that the respiratory nurse specialist is in an ideal position to implement changes to improve the patient's experience of chronic disease management.

Arterial blood gas and pulse oximetry in initial management of patients with community-acquired pneumonia.

OBJECTIVE: To identify the factors associated with the use of arterial blood gas (ABG) and pulse oximetry (PO) in the initial management of patients with community-acquired pneumonia (CAP) and arterial hypoxemia at presentation. PARTICIPANTS: A total of 944 outpatients and 1,332 inpatients with clinical and radiographic evidence of CAP prospectively enrolled from 5 study sites in the United States and Canada. ANALYSES: Separate multivariate logistic regression analyses were used to 1) compare measurement of ABG and PO within 48 hours of presentation across sites while controlling for patient differences, and 2) identify factors associated with arterial hypoxemia (PaO2 <60 mm Hg or SaO2 <90% for non-African Americans and <92% for African Americans) while breathing room air. RESULTS: Range of ABG use by site was from 0% to 6.4% (P =.06) for outpatients and from 49.2% to 77.3% for inpatients (P <.001), while PO use ranged from 9.4% to 57.8% for outpatients (P <.001) and from 47.9% to 85.1% for inpatients (P <.001). Differences among sites remained after controlling for patient demographic characteristics, comorbidity, and illness severity. In patients with 1 or more measurements of oxygenation at presentation, hypoxemia was independently associated with 6 risk factors: age >30 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.7 to 5.9), chronic obstructive pulmonary disease (OR, 1.9; 95% CI, 1.4 to 2.6), congestive heart failure (OR, 1.5; 95% CI, 1.0 to 2.1), respiratory rate >24 per minute (OR, 2.3; 95% CI, 1.8 to 3.0), altered mental status (OR, 1.6; 95% CI, 1.1 to 2.3), and chest radiographic infiltrate involving >1 lobe (OR, 2.2; 95% CI, 1.7 to 2.9). The prevalence of hypoxemia among those tested ranged from 13% for inpatients with no risk factors to 54.6% for inpatients with > or =3 risk factors. Of the 210 outpatients who had > or =2 of these risk factors, only 64 (30.5%) had either an ABG or PO performed. In the 48 outpatients tested without supplemental O2 with > or =2 risk factors 8.3% were hypoxemic. CONCLUSIONS: In the initial management of CAP, use of ABG and PO varied widely across sites. Increasing the assessment of arterial oxygenation among patients with CAP is likely to increase the detection of arterial hypoxemia, particularly among outpatients.