Portable Blood Gas Research Articles

23 NEONATAL SUPPORT THERAPY AND BLOOD GAS EVALUATION IN CLONED AND ARTIFICIAL INSEMINATION-DERIVED NEWBORN CALVES

Offspring derived from artificial reproductive techniques are already known to present several postnatal undesirable phenotypes and clinical disorders. Despite its benefits, cloning by somatic cell nuclear transfer (SCNT) is extremely inefficient. The birth rate in cattle is around 5% of the transferred blastocysts, and ~50% of delivered calves die in the first 48 h. Neonatal respiratory distress is reported to be one of the main causes of such deaths. Veterinary intervention is often needed to promote or improve blood oxygenation, avoiding respiratory acidosis and improving carbon dioxide delivery from blood/lungs to the environment. This study aimed to evaluate a neonatal support therapy over the blood gas and acid-base balance on newborn calves derived from SCNT or AI. Four cloned and 3 AI-derived calves delivered by Caesarean section were used for the experiment. Postnatal therapeutic procedures were comprised 4 doses of 400 mg of intratracheal surfactant every 15 min, 25 mg of oral sildenafil every 8 h for 3 days, and 5 L min–1 intranasal oxygen. Blood collections were performed within 30 min (T0), at 12 (T12), 24 (T24) and 48 (T48) hours after delivery. Blood samples were collected from the caudal auricular artery with a butterfly and a blood gas syringe. Oxygen saturation (sO2), arterial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), pH, and bicarbonate (HCO3–) were evaluated with a portable blood gas analyzer (i-STAT, Abbott Point of Care Inc., Princeton, NJ, USA). Data obtained were submitted to ANOVA (Proc MIXED; SAS/STAT, version 9; SAS Institute Inc., Cary, NC, USA). There were significant differences between groups in blood pH (P = 0.0182) and between groups (P = 0.0281) and time of collection (P = 0.0303) in blood bicarbonate (HCO3–). The AI calves were born with normal pH (7.468 ± 0.033) and the cloned calves were born in acidosis (7.216 ± 0.166). These calves were stabilised in T48 (7.427 ± 0.017) using their own HCO3– that increased over time. Although there were no differences in sO2 (P = 0.4525), PaO2 (P = 0.3086), or PaCO2 (P = 0.2514), sO2 and PaO2 were numerically increased at the same time that PaCO2 decreased in both groups. In the cloned calves, the sO2, PaO2, and PaCO2 at T0 were 61.3 ± 28.6%, 39.8 ± 18.5 mmHg, and 65.8 ± 29.3 mmHg, respectively and reached 90.0 ± 3.4%, 57.7 ± 15.8 mmHg, and 42.0 ± 3.7 mmHg. In the AI calves, T0 blood gas analysis were 79.8 ± 19.4%, 56.1 ± 42.1 mmHg, and 39.1 ± 4.8 mmHg, and at T48 were 89.0 ± 2.6%, 82.3 ± 43.5 mmHg, and 43.0 ± 4.9 mmHg for sO2, PaO2, and PaCO2 respectively. The neonate support therapy improved calves' oxygenation and helped to eliminate the carbon dioxide from the blood. In our experience, the neonatal treatment was essential in supporting the lives of the cloned calves.Funding support was received from FAPESP 2011/19543–9.

Parâmetros hemogasométricos e equilíbrio ácido-básico de cabritos nascidos de partos normais

A adaptação à vida extra-uterina é período crítico para o recém-nascido. Inúmeras alterações ocorrem em diferentes sistemas e órgãos, incluindo a função respiratória e o equilíbrio ácido-básico. O presente trabalho objetivou constatar a ocorrência de acidose em cabritos recém-nascidos e obter parâmetros gasométricos e ácido-básicos dos mesmos, até as 24 horas de vida. Para tanto, foram utilizados 33 cabritos, sem distinção de sexo. Amostras sanguíneas foram colhidas por venopunção jugular, imediatamente após o nascimento, aos cinco, dez e 15 minutos, e às 24 horas de vida, para determinação do pH, pressão parcial de oxigênio (pO2), pressão parcial de dióxido de carbono (pCO2), dióxido de carbono total (TCO2), concentração de bicarbonato (HCO3), excesso de bases (BE) e a saturação de oxigênio (sO2) utilizando-se analisador portátil de gases sanguíneos. Observaram-se diferenças significativas entre os momentos nos valores gasométricos dos cabritos em todas as variáveis estudadas. Os cabritos recém-nascidos apresentaram acidose respiratória no período pós-parto imediato, normalizando-se às 24 horas de vida.

Capture, Anesthesia, and Disturbance of Free-Ranging Brown Bears (Ursus arctos) during Hibernation

We conducted thirteen immobilizations of previously collared hibernating two- to four-year-old brown bears (Ursus arctos) weighing 21–66 kg in central Sweden in winter 2010 and 2011 for comparative physiology research. Here we report, for the first time, an effective protocol for the capture and anesthesia of free-ranging brown bears during hibernation and an assessment of the disturbance the captures caused. Bears were darted in anthill, soil, or uprooted tree dens on eleven occasions, but two bears in rock dens fled and were darted outside the den. We used medetomidine at 0.02–0.06 mg/kg and zolazepam-tiletamine at 0.9–2.8 mg/kg for anesthesia. In addition, ketamine at 1.5 mg/kg was hand-injected intramuscularly in four bears and in six it was included in the dart at 1.1–3.0 mg/kg. Once anesthetized, bears were removed from the dens. In nine bears, arterial blood samples were analyzed immediately with a portable blood gas analyzer. We corrected hypoxemia in seven bears (PaO2 57–74 mmHg) with supplemental oxygen. We placed the bears back into the dens and antagonized the effect of medetomidine with atipamezole. Capturing bears in the den significantly increased the risk of den abandonment. One of twelve collared bears that were captured remained at the original den until spring, and eleven, left their dens (mean ± standard deviation) 3.2±3.6 (range 0.5–10.5) days after capture. They used 1.9±0.9 intermediate resting sites, during 6.2±7.8 days before entering a new permanent den. The eleven new permanent dens were located 730±589 m from the original dens. We documented that it was feasible and safe to capture hibernating brown bears, although they behaved differently than black bears. When doing so, researchers should use 25% of the doses used for helicopter darting during the active period and should consider increased energetic costs associated with den abandonment.

The Measure of Treatment Agreement Between Portable and Laboratory Blood Gas Measurements in Guiding Protocol-Driven Ventilator Management

The Measure of Treatment Agreement Between Portable and Laboratory Blood Gas Measurements in Guiding Protocol-Driven Ventilator Management

The role of pre-hospital blood gas analysis in trauma resuscitation

BackgroundTo assess, whether arterial blood gas measurements during trauma patient's pre-hospital shock resuscitation yield useful information on haemodynamic response to fluid resuscitation by comparing haemodynamic and blood gas variables in patients undergoing two different fluid resuscitation regimens.MethodsIn a prospective randomised study of 37 trauma patients at risk for severe hypovolaemia, arterial blood gas values were analyzed at the accident site and on admission to hospital. Patients were randomised to receive either conventional fluid therapy or 300 ml of hypertonic saline. The groups were compared for demographic, injury severity, physiological and outcome variables.Results37 patients were included. Mean (SD) Revised Trauma Score (RTS) was 7.3427 (0.98) and Injury Severity Score (ISS) 15.1 (11.7). Seventeen (46%) patients received hypertonic fluid resuscitation and 20 (54%) received conventional fluid therapy, with no significant differences between the groups concerning demographic data or outcome. Base excess (BE) values decreased significantly more within the hypertonic saline (HS) group compared to the conventional fluid therapy group (mean BE difference -2.1 mmol/l vs. -0.5 mmol/l, p = 0.003). The pH values on admission were significantly lower within the HS group (mean 7.31 vs. 7.40, p = 0.000). Haemoglobin levels were in both groups lower on admission compared with accident site. Lactate levels on admission did not differ significantly between the groups.ConclusionPre-hospital use of small-volume resuscitation led to significantly greater decrease of BE and pH values. A portable blood gas analyzer was found to be a useful tool in pre-hospital monitoring for trauma resuscitation.

The Measure of Treatment Agreement Between Portable and Laboratory Blood Gas Measurements in Guiding Protocol-Driven Ventilator Management

Portable blood gas analyzer and monitor devices are increasingly being used to direct ventilator therapy. The purpose of this study was to evaluate the "measure of treatment agreement" between portable and laboratory blood gas measurements used in guiding protocol-driven ventilator management. Using National Institutes of Health Acute Respiratory Distress Syndrome network ventilator management guidelines to manage patient care, measurements taken from the Nonin 8500 M pulse oximeter (SpO2), the Novametrix-610 end-tidal CO2 (ETCO2) detector, and the i-STAT 1 (SaO2, PO2, pH, PCO2) were compared with the recommended treatment from paired laboratory ABL-725 (SaCO2, PO2, pH, PCO2) measurements. Four hundred forty-six intubated adult intensive care unit patients were studied prospectively. Except for the ETCO2 (R2 = 0.460), correlation coefficients between portable and laboratory measurements were high (R2 > or = 0.755). Testing for equivalence, the Nonin-SpO2, iSTAT-PO2, iSTAT-pH, and iSTAT-PCO2 were deemed "equivalent" surrogates to paired ABL measurements. Testing for the limits of agreement found only the iSTAT-PCO2 to be an acceptable surrogate measurement. The measure of treatment agreement between the portable and paired laboratory blood gas measurements were Nonin-SpO2 (68%), iSTAT-SaO2 (73%), iSTAT-PO2 (97%), iSTAT-pH (88%), iSTAT-PCO2 (95%), and Novametrix-ETCO2 (60%). Only the iSTAT-PO2 and the iSTAT-PCO2 achieved the > or =95% treatment agreement threshold to be considered as acceptable surrogates to laboratory measurements. : The iSTAT-PO2 and -PCO2 were portable device measurements acceptable as surrogates to standard clinical laboratory blood gas measurements in guiding protocol-directed ventilator management. The "measure of treatment agreement," based on standardized decisions and measurement thresholds of a protocol, provides a simple method for assessing clinical validity of surrogate measurements.

Evaluation of QC3

Objective: The ABL80 FLEX (Radiometer-Copenhagen, Denmark) is a portable blood gas analyzer for blood gas (pH, PCO2 ,P O 2), electrolyte (Na, K, Cl), ionized calcium, and hematocrit testing. The analyzer has an onboard quality control system, QC 3 ,t hat automatically calibrates, performs 3 levels of aqueous quality control, and conducts system checks to establish and verify analyzer performance. This study evaluated the ability of the QC 3 system to detect potential sources of error that may affect patient results. Methodology: External, surrogate quality control samples were analyzed 3 times a day for 30 days to determine the equivalence of external and onboard quality control. In addition, the analyzer was challenged with air bubbles during control and specimen analysis and

Research at the Extremes: Lessons from the 1981 American Medical Research Expedition to Mt Everest

On October 24, 1981, Chris Pizzo and Yong Tenzing, members of the American Medical Research Expedition to Mt Everest (AMREE), stood on the highest point on earth and collected 6 alveolar gas samples. These, together with further data collected from the South Col (8050 m), provided the foundations for what is surely one of the most unique field experiments ever undertaken—the calculation of arterial blood gases from a mountaineer on the summit of Mt Everest (8848 m; Table). Without the accurate portable blood gas analyzers that many of us now take for granted, the AMREE team used the ‘‘Bohr Integration,’’ a complex computational method used primarily to calculate the diffusion capacity of oxygen inside the human lungs. By assuming this value, the AMREE team was able to calculate the mean alveolar-capillary PO2 difference and therefore deduce the PO2 of arterial blood. However, to complete this, a long list of measurements and assumptions would need to be made first, and it is this attention to detail that makes ‘‘Pulmonary Gas Exchange on the Summit of Mt Everest’’ such an exceptional piece of work.1 In what Edouard Wyss Dunant, the leader of the unsuccessful 1952 Swiss Expedition to Mt Everest, once described as the ‘‘todeszone’’ or ‘‘death zone,’’ the AMREE team conducted an unparalleled set of tests. Not only did they record the first accurate barometric pressure reading on the summit of Mt Everest, but they were also able to obtain 42 resting alveolar gas samples from various sites above 8000 m (Figure 1). These results showed, for the first time, the dramatic fall in alveolar

Transit care of the ventilated critically ill in commercial airliners

Air ambulances and customized military aircraft are established modes of transporting critically ill patients. Defence services and aid agencies even have flying hospitals, replete with operating theatres and ICUs. With burgeoning travel by an increasingly elderly population, a growing number of travelling Australians suffer critical illnesses overseas. Transcontinental air ambulances are prohibitively expensive and many American and European commercial airlines ban travel by seriously ill patients. Transit intensive care on board commercial airline flights poses complex physiological and logistic challenges. We have transported hundreds of critically ill patients and report on 10 episodes of aero-intensive care with IPPV on board scheduled passenger services. These were from the Philippines, the USA, the United Kingdom, Thailand, France, Norway and Austria on Qantas, Singapore Airlines, Thai Airways and Malaysia Airlines. The aviation environment imposes a bewildering array of electronic, safety and security related issues to be overcome. The entire mobile ICU weighs 100 kg. A vacuum-mattress on a stretcher fitted to the cabin floor at the rear of the economy-class cabin and screened off from the other passengers ensures patient privacy (Fig. ​(Fig.1).1). Oxygen is scarce and extremely expensive during flight. We employed the 'circle system' with a CO2 absorber and in-line oxygen analyser. Mobile suction, infusion pumps, transit-care monitors and portable blood gas analysers were all adapted for use in commercial aircraft. Figure 1 Australia and New Zealand lead the world in transit care of the critically ill in commercial airliners.

휴대형 혈액가스분석 시스템의 구현 및 성능평가

본 연구에서는 동맥혈액 내의 혈액가스(pH, <TEX>$pCO_2$</TEX>, <TEX>$pO_2$</TEX>)를 측정할 수 있는 휴대용 혈액가스 분석 시스템을 구현하였다. 구현된 시스템은 크게 하드웨어부와 소프트웨어부로 구분하였으며, 하드웨어부는 메커니즘과 전자회로부로 구분하여 설계하였다. 소프트웨어부는 각 모듈별로 작성하였으며, 운용프로그램, 세척프로그램, 교정프로그램, 측정프로그램 등으로 구성하였다. 그리고 시스템의 정확한 교정을 위하여 2점 교정방식을 사용하였고, 1점 보정방식을 추가 적용하여 측정의 정확성을 높이고자 하였다. 시스템의 평가를 위하여 각 전극의 감응특성을 조사하였다. 그리고 정확도 평가를 위하여 표준용액을 이용하여 측정실험을 하고 통계적인 분석을 하였다. 그 결과 계수변화율이 1.12이내이었고, 최대오차가 1.298%이내인 정확도를 나타내었으며, 휴대형 ABGA의 개발 가능성을 확인하였다. In this study, we implemented the measurement of pH, <TEX>$pO_2$</TEX>, <TEX>$pCO_2$</TEX> of the arterial blood on a portable blood gas analysis system. This system is consist of two parts of hardware and software. The hardware part is divided into a fluidic mechanism and an electronic circuit unit. The system program is composed of operating, washing, correcting, and measuring routines. Both of 1-point and 2-point calibration schemes were used to enhance the accuracy of the measurement. In order to evaluate the performance of the developed system, we measured and performed statistical analysis on the characteristics of the sensing electrode response. As a result, coefficient variation was within 1.12, and maximum error was within 1.298%. We confirmed development possibility of portable blood gas analyzer.

Analytical performance of a portable critical care blood gas analyzer

The portable blood gas analyzer OPTI Critical Care Analyzer was evaluated in comparison to routine laboratory assays using heparinized blood samples of adults and newborns. Within-run imprecision studies were performed with native blood using tonometry to adjust blood gas concentrations. The results obtained show a very close agreement between the OPTI system and the comparison methods for all parameters tested: hemoglobin (y=1.00x−0.2 g/l, r=0.997, n=81), sodium (y=1.13x−18.7 mmol/l, r=0.951, n=79), potassium (y=1.03x−0.04 mmol/l, r=0.972, n=79), pH (y=1.03x−0.29, r=0.958, n=57), pCO2 (y=1.03x−1.14 mm Hg, r=0.988, n=57) and pO2 (y=1.07x−0.85 mm Hg, r=0.995, n=57). The coefficients of variation for the within-run imprecision were below 1.1% for sodium and hemoglobin, and below 2.6% for all other parameters, except for pCO2 with coefficients of variation up to 3.6% at low calibration gas concentrations. Due to this analytical performance and its portability, the OPTI system is well suited for low to medium test frequencies and immediate use in emergency rooms, intensive care or surgery units.

Systematic instrumental errors between oxygen saturation analysers in fetal blood during deep hypoxemia

Background: During a study of artificially produced deep hypoxemia in fetal cord blood, systematic errors of three different oxygen saturation analysers were evaluated against a reference CO oximeter. Methods: The oxygen tensions (PO2) of 83 pre-heparinized fetal blood samples from umbilical veins were reduced by tonometry to 1.3 kPa (10 mm Hg) and 2.7 kPa (20 mm Hg). The oxygen saturation (SO2) was determined (n=1328) on a reference CO oximeter (ABL625, Radiometer Copenhagen) and on three tested instruments (two CO oximeters: Chiron865, Bayer Diagnostics; ABL700, Radiometer Copenhagen, and a portable blood gas analyser, i-STAT, Abbott). The CO oximeters measure the oxyhemoglobin and the reduced hemoglobin fractions by absorption spectrophotometry. The i-STAT system calculates the oxygen saturation from the measured pH, PO2, and PCO2. The measurements were performed in duplicate. Statistical evaluation focused on the differences between duplicate measurements and on systematic instrumental errors in oxygen saturation analysis compared to the reference CO oximeter. Results: After tonometry, the median saturation dropped to 32.9% at a PO2=2.7 kPa (20 mm Hg), defined as saturation range 1, and to 10% SO2 at a PO2=1.3 kPa (10 mm Hg), defined as range 2. With decreasing SO2, all devices showed an increased difference between duplicate measurements. ABL625 and ABL700 showed the closest agreement between instruments (0.25% SO2 bias at saturation range 1 and −0.33% SO2 bias at saturation range 2). Chiron865 indicated higher saturation values than ABL 625 (3.07% SO2 bias at saturation range 1 and 2.28% SO2 bias at saturation range 2). Calculated saturation values (i-STAT) were more than 30% lower than the measured values of ABL625. Conclusions: The disagreement among CO oximeters was small but increasing under deep hypoxemia. Calculation found unacceptably low saturation.

Multiple site analytical evaluation of a portable blood gas/electrolyte analyzer for point of care testing.

To evaluate the analytical performance of the SenDx 100 portable blood gas and electrolyte analyzer (SenDx Medical, Carlsbad, CA). Accuracy was evaluated by correlation of whole blood patient samples with the Nova Stat Profile 5 (Nova Biomedical, Waltham, MA) and the Ciba Corning 865 (Chiron Diagnostics, Medford, MA). Precision was evaluated using quality control materials (RNA Medical, Acton, MA). Critical care laboratories and operating rooms in two institutions. Precision studies performed at three different concentration levels for each analyte demonstrated intra-assay precision of < or =2.5% coefficient of variation and interassay precision of < or =4.0% coefficient of variation in all cases. Analysis of patient specimens in general showed good to excellent correlation to reference analyzers. Regression variables are tabulated. The SenDx 100 portable blood gas and electrolyte analyzer is a simple and easy to use analyzer demonstrating acceptable performance compared with reference methods.

Accuracy of a Portable Blood Gas Analyzer Incorporating Optodes for Canine Blood

The accuracy of a portable blood gas analyzer (OPTI 1) was evaluated using canine blood and aqueous control solutions. Sixty‐four arterial blood samples were collected from 11 anesthetized dogs and were analyzed for pH, partial pressure of carbon dioxide (Pco2), partial pressure of oxygen (Po2), and bicarbonate concentration ([HCO3‐]) values by the OPTI 1 and a conventional blood gas analyzer (GASTAT 3). The conventional analyzer was considered as a standard against which the OPTI 1 was evaluated. Comparison of OPTI 1 results with those of GASTAT 3 by linear regression analysis revealed a high degree of correlation with the GASTAT 3 (r= .90‐.91). The mean ± SD of the differences between OPTI 1 and GASTAT 3 values was ‐0.008 ± 0.017 for pH, ‐0.88 ± 3.33 mm Hg for Pco2, 3.71 ± 6.98 mm Hg for Po2, and ‐0.34 ± 1.45 mEq/L for [HCO3‐]. No statistically significant difference was found between the OPTI 1 and the GASTAT 3. Agreement between these 2 methods is within clinically acceptable ranges for pH, Pco2, Po2, and [HCO3‐]. The coefficients of variation for measured pH, Pco2, and Po2 values of 3 aqueous control solutions (acidic, normal, and alkalotic) analyzed by the OPTI 1 ranged from 0.047 to 0.072% for pH, 0.78 to 1.81% for Pco2, and 0.73 to 2.77% for Po2. The OPTI 1 is concluded to provide canine blood gas analysis with an accuracy that is comparable with that of conventional benchtop blood gas analyzers.

In-vivo measurement of intrauterine gases and acid-base values early in human pregnancy.

A new multiparameter sensor that combines electrochemical and fibre-optic technology was used for continuous in-vivo investigation of pH, carbon dioxide partial pressure (PCO(2)), oxygen partial pressure (PO(2)), bicarbonate concentration (HCO(3)(-)), base excess, and oxygen saturation (O(2)Sat) early in human pregnancy. The sensor was inserted into the amniotic cavity and the placental bed of 16 pregnancies at 10-15 weeks gestation, before termination under general anaesthesia. Amniotic fluid and retroplacental blood from the same site were also aspirated and analysed by means of cartridges and a portable blood gas analyser. Eleven series of measurements were obtained. The variation in measurements over the 5 min of monitoring was </=10% for all parameters. The sensor was damaged during insertion into the amniotic cavity in one case and in the placental bed in four cases. Measurements of PO(2) in both the amniotic cavity and the placental bed and of pH in the placental bed were higher using the cartridges than in vivo. The results indicated that in-vivo monitoring of fetoplacental gas and acid-base with a sensor is stable and accurate. Such technology will be helpful in improving our understanding of the fetoplacental metabolism in normal and complicated pregnancies.

Clinical Evaluation of the Portable Blood Gas Analyzer in the Developing Country

Clinical Evaluation of the Portable Blood Gas Analyzer in the Developing Country

Portable blood gas and electrolyte analyzer evaluated in a multiinstitutional study.

A recently introduced blood gas/electrolyte analyzer (SenDx 100((R)), renamed ABL70) intended for point-of-care, near-patient, or stat laboratory use was evaluated simultaneously in four different institutions and compared with three different laboratory bench analyzers with respect to imprecision, inaccuracy (assessed by tonometry), and patient-sample analyses. The analyzer is equipped with a sensor cassette and a reagent cartridge for 50, 100, or 200 analyses and 100 or more traditional quality-control measurements. One analysis requires 170 microL of whole blood and takes <90 s. Statistically, the instrument performed somewhat better (lower CVs) for PO2 and potassium and somewhat worse for pH, PCO2, and ionized calcium than the respective comparison analyzers. However, the overall performance (in terms of CV and accuracy) was satisfactory in terms of clinical (e.g., CLIA '88) goals in all institutions. The mean difference and the CV of that difference in some 400 patient-sample comparisons were as follows: 0.010 (+/- 0.002%) for pH, -0.65 mmHg (+/- 4%) for PCO2, -0.49 mmHg (+/- 6%) for Po2, 0.44 mmol/L (+/- 1.2%) for sodium, -0.013 mmol/L (+/- 2.9%) for potassium, -0.016 mmol/L (+/- 2.6%) for ionized calcium, and -0.016 L/L (+/- 7. 1%) for the hematocrit. Its acceptable analytical performance and ease of operation make the SenDx 100 suitable for the analysis of blood gases and electrolytes.

Accuracy and precision of the portable StatPal II and the laboratory-based NOVA stat profile 1 for measurement of pH, P(CO2), and P(O2) in equine blood.

To investigate the accuracy and precision of the portable, battery-powered StatPal II and the laboratory-based NOVA StatProfile 1 blood gas and pH analyzers for use in analysis of equine blood. Patient sample comparison and whole blood tonometry. Patient sample comparison: 125 arterial or venous blood samples from 49 healthy, awake, or anesthetized horses or ponies. Tonometry: venous blood samples from 11 healthy Thoroughbred horses. Arterial and venous blood taken from awake and anesthetized equine patients was placed in an ice-water bath, then analyzed within 30 minutes of collection. Bias and limits of agreement between analyzers in measurement of pH, P(CO2), and P(O2) were calculated according to the method of Bland and Altman. Tonometry, using analyzed gases with a range of P(O2) of 28 to 286 mm Hg and P(CO2) of 21 to 85 mm Hg, was performed on equine whole blood or blood with abnormally high (55%) or low (20%) hematocrit. Samples were introduced directly from the tonometer into the analyzers. Inaccuracy (% of target value) and imprecision (coefficient of variation) were determined for each instrument. In addition, results of analysis of blood samples introduced into the analyzers at 36 degrees C, 0 to 3 degrees C, and 22 degrees C were compared. In the patient sample comparisons, bias between analyzers (StatPal-NOVA) for measurement of P(O2) less than 60 mm Hg was -0.33+/-6.2 mm Hg (x +/-2 SD) and for P(O2) between 60 and 110 mm Hg bias was -1.48+/-9.2 mm Hg. Bias was 46.5+/-67 mm Hg (significantly different from bias at the lower P(O2) levels) for measurement of P(O2) values of 111 to 505 mm Hg, and at P(O2) values greater than 110 mm Hg, bias increased with increasing P(O2). During the course of the study, a significant shift in bias between instruments occurred for P(CO2) and pH measurement, coincident with a change of P(CO2) and pH electrodes in the NOVA and use of a new lot of StatPal sensors. Bias (StatPal-NOVA) for P(CO2) before and after the electrode change was -3.74+/-4.2 and -0.88+/-6.8 mm Hg, and bias for pH before and after the electrode change was 0.026+/-0.034 and -0.024+/-0.038. The change in bias was significant (P<.05). In the whole blood tonometry trials, mean recovered values of P(CO2) and P(O2) from blood with a normal hematocrit ranged from 94% to 109% of target values for StatPal and from 98% to 107% for NOVA. Imprecision ranged from 3.3% to 5.3% for StatPal and from 2.2% to 4.3% for NOVA. With extremes of hematocrit (55% and 20%), StatPal's mean recovered P(CO2) values were 115% and 112% of the target value of 21 mm Hg, whereas NOVA's recovered P(CO2) values were similar to those recovered from samples with normal hematocrit. Introduction of cold blood samples (0 to 3 degrees C) into StatPal resulted in P(CO2) readings that were approximately 2 mm Hg lower than those of 22 degrees C and 36 degrees C samples (P<.05). No other effects of sample temperature were found for either instrument. StatPal and NOVA are of similar accuracy and demonstrate acceptable precision for measurement of P(CO2) and P(O2) in equine blood with values in the normal arterial and venous range. Mean recovered values during tonometry differed by as much as 10% between instruments, indicating that they should not be used interchangeably for a single patient or for a group of subjects in a research setting. The StatPal is a portable blood gas analyzer of acceptable accuracy and precision, for clinical or investigational work in horses.

Accuracy of a portable blood gas analyzer incorporating optodes for canine blood.

The accuracy of a portable blood gas analyzer (OPTI 1) was evaluated using canine blood and aqueous control solutions. Sixty-four arterial blood samples were collected from 11 anesthetized dogs and were analyzed for pH, partial pressure of carbon dioxide (PCO2) partial pressure of oxygen (PO2), and bicarbonate concentration ([HCO3-]) values by the OPTI 1 and a conventional blood gas analyzer (GASTAT 3). The conventional analyzer was considered as a standard against which the OPTI 1 was evaluated. Comparison of OPTI 1 results with those of GASTAT 3 by linear regression analysis revealed a high degree of correlation with the GASTAT 3 (r = .90-.91). The mean +/- SD of the differences between OPTI 1 and GASTAT 3 values was -0.008 +/- 0.017 for pH, -0.88 +/- 3.33 mm Hg for PCO2, 3.71 +/- 6.98 mm Hg for PO2, and -0.34 +/- 1.45 mEq/L for [HCO3-]. No statistically significant difference was found between the OPTI 1 and the GASTAT 3. Agreement between these 2 methods is within clinically acceptable ranges for pH, PCO2, PO2, and [HCO3-]. The coefficients of variation for measured pH, PCO2, and PO2 values of 3 aqueous control solutions (acidic, normal, and alkalotic) analyzed by the OPTI 1 ranged from 0.047 to 0.072% for pH, 0.78 to 1.81% for PCO2, and 0.73 to 2.77% for PO2. The OPTI 1 is concluded to provide canine blood gas analysis with an accuracy that is comparable with that of conventional benchtop blood gas analyzers.

Evaluation of a portable blood gas analyzer for pediatric interhospital transport

We evaluated a portable blood gas analyzer for its speed, reliability, and usefulness during interhospital transportation of critically ill children in a prospective study. The accuracy of a portable blood gas analyzer (PBGA) was first established by comparing its results with values obtained from a standard blood gas analyzer. The speed, accuracy, and usefulness of the PBGA were then compared with those of standard analyzers at 10 referring hospitals during interhospital transportation of critically ill children. A highly significant linear correlation was demonstrated between values obtained using the PBGA and those derived from standard analyzers. The time required to obtain blood gas results was 2 min with the portable device, significantly less than the mean of 8.4 min ± 6.4 min (range 1–24 min) required to get results from the laboratory facilities of the referring hospitals. Modification of treatment or adjustment to mechanical ventilation was required in 30% of transported patients based on blood gas results obtained immediately before departure from the referring hospital. We conclude that a portable blood gas analyzer provides rapid, reliable, and useful data that help to determine therapy for critically ill children awaiting interhospital transport.