Suzanne Murphy

Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions.

OBJECTIVE To compare intraosseous with central venous blood samples for biochemical analyses and hemoglobin levels during cardiopulmonary resuscitation (CPR) and during cardiopulmonary resuscitation with infusion of sodium bicarbonate, epinephrine, and saline boluses through the intraosseous site. DESIGN Prospective, complete repeated measures study. SETTING An animal laboratory at a university medical center. SUBJECTS Thirty-two piglets (mean weight, 30 [range, 24-35] kg). INTERVENTIONS Animals were anesthetized, instrumented, and subjected to hypoxic cardiac arrest. An intraosseous cannula was inserted into the tibia, and animals were randomly assigned to one of five groups: heparinized saline (n = 6), epinephrine infusions only (n = 6), saline infusions only (n = 6), sodium bicarbonate infusions only (n = 8), and epinephrine, saline, and sodium bicarbonate infusions through the same site (n = 6). CPR (chest compressions and mechanical ventilation) was performed in all groups. Simultaneous blood samples were taken from the central venous and intraosseous sites before arrest and after 5 and 30 mins of CPR. MEASUREMENTS AND MAIN RESULTS There were no differences (p < .05) in sodium, potassium, magnesium, lactate, and calcium values of intraosseous and central venous blood at the baseline and during 5 mins of CPR with infusions through the intraosseous cannula. At 30 mins, differences were apparent in magnesium, potassium, and sodium values between groups when the intraosseous cannula was used for infusions as well as sampling. Intraosseous potassium, glucose, and magnesium values were lower and sodium values were higher than central venous blood levels. No differences were seen at all sampling intervals if small-volume heparinized saline was given through the intraosseous site. Hemoglobin values were lower in the intraosseous group after 30 mins of CPR and infusions through the intraosseous site. After 30 mins of CPR, all hemoglobin values from the intraosseous site were <10 g/100 mL. CONCLUSION Intraosseous and central venous blood biochemical and hemoglobin values were similar during hemodynamic stability and throughout 30 mins of resuscitation if no drugs were given through the intraosseous site. However, differences existed after 30 mins of CPR and infusions through the intraosseous site. Laboratory values may be erroneous when intraosseous blood is used during periods of resuscitation of >5 mins if drugs and fluid boluses have also been infused through the site. For reliable values, an intraosseous site for sampling only may be reasonable.

Exhaled nitric oxide reflects asthma severity and asthma control.

Introduction This study was undertaken to a) evaluate whether exhaled nitric oxide (fraction of exhaled nitric oxide [Feno]) levels are reflective of asthma severity in concordance with the National Asthma Education and Prevention Program categorization and b) determine the usefulness of Feno using the single-breath exhalation technique for monitoring asthma control and compliance with steroid treatment. Methods Thirty patients with asthma (7–17 yrs old; 14 males and 16 females) that was mild (n = 8), moderate (n = 17), or severe (n = 5) were included in the study. Fifteen patients were seen on more than one occasion for a total of 53 visits. Information obtained at each visit included asthma symptoms, &bgr;-agonists and corticosteroids use, compliance to steroids, and forced expiratory volume in 1 sec (Fev1) and Feno measurements. Asthma control was judged by a pulmonologist based on overall evaluation of symptoms, Fev1 measurements, and the frequency of &bgr;-agonists use at each visit. Results The mean ± sd Feno was significantly different in the mild, moderate, and severe asthma categories (30 ± 12, 65 ± 48, 104 ± 68, respectively; F2,52 = 6.02 p = .005). Feno was significantly correlated with asthma severity (r = .44, p = .001), compliance (r = −.75, p = .001), and control (r = −.51, p = .001). There were no statistically significant differences between asthma severity and compliance or Fev1. Discussion Our data suggest that a) Feno may be a practical tool to evaluate asthma severity and asthma control over time and b) Feno may be used as a marker of compliance with steroids even when Fev1 has not decreased significantly.

Comparison of the HOTV and Lea Symbols Charts for Preschool Vision Screening

PURPOSE Two preliterate acuity charts, the Lea Symbol chart and the HOTV chart, were compared prospectively in an established preschool vision screening program. The charts were compared by measuring time required to test, reliability coefficients, and the percentage of children testable with each chart. METHODS AND MATERIALS Seven hundred and seventy-seven 3- to 5-year-old children were randomized to four screening sequences that determined the order of chart use. Each child was screened on two occasions within 6 weeks. Testing was performed at 10 feet, and optotypes were not isolated for testing. RESULTS Mean test time was significantly less for older children, but was not related to the chart used. Reliability coefficients were similar for the Lea Symbols and the HOTV charts. The percentage of children testable by each chart improved with increased age of the child. More 3 year olds were testable with the Lea Symbols chart compared to the HOTV chart (92% versus 85%, P = .05). CONCLUSIONS Vision screening with either chart was more rapid and more frequently achieved with 4- and 5-year-old children compared with the 3 year olds. For the population as a whole, each chart gave similar results. Among the 3 year olds, however, testability rates were better for the Lea Symbols chart. The Lea Symbols chart is an acceptable option for preschool vision screening, and may be more efficacious than the HOTV chart for screening 3-year-old children.

Acid-base status of blood from intraosseous and mixed venous sites during prolonged cardiopulmonary resuscitation and drug infusions.

OBJECTIVES a) To determine the relationship of acid-base balance (pH, PCO2) of blood samples from the intraosseous and the mixed venous route during prolonged cardiopulmonary resuscitation; b) to compare the effect of separate infusions of epinephrine, fluid boluses, or sodium bicarbonate through the intraosseous sites on the acid-base status of intraosseous and mixed venous blood during cardiopulmonary resuscitation; and c) to compare pH and Pco2 of intraosseous and mixed venous blood samples after sequential infusions of fluid, epinephrine, and sodium bicarbonate through a single intraosseous site. DESIGN Prospective, randomized study. SETTING Animal laboratory at a university center. SUBJECTS Thirty-two mixed-breed piglets (mean weight, 30 kg). INTERVENTIONS Piglets were anesthetized and prepared for blood sampling and cardiopulmonary resuscitation. After anoxic cardiac arrest, ventilation was resumed and chest compression was resumed. Blood gas samples from the pulmonary artery and both intraosseous sites were obtained simultaneously at baseline, at cardiac arrest, and at 5, 10, 15, 20, and 30 mins of cardiopulmonary resuscitation for group 1 (control group) and after drug (epinephrine and sodium bicarbonate) and saline infusions via one of the intraosseous cannulas in groups 2 through 5. MEASUREMENTS AND MAIN RESULTS We found no differences between intraosseous and mixed venous pH and Pco2 during periods of <15 mins of cardiopulmonary resuscitation. However, this relationship was not maintained during prolonged cardiopulmonary resuscitation and after bicarbonate infusion. After large volume saline infusion, the pH and Pco2 of mixed venous and intraosseous blood were similar. During epinephrine infusion, the relationship between intraosseous and mixed venous pH and Pco2 was similar to that found in the control group. CONCLUSIONS The intraosseous blood sample could be used to assess central acid-base balance in the early stage of arrest and cardiopulmonary resuscitation of <15 mins. However, during cardiopulmonary resuscitation of longer duration, drug infusions may render the intraosseous site inappropriate for judging central acidosis.

Exhaled nitric oxide measurements in childhood asthma : Techniques and interpretation

In this review, we outline the role of nitric oxide in airway inflammation in children with asthma. We also discuss the various methods reported for measuring exhaled nitric oxide and provide some insight as to the pros and cons and pitfalls of these techniques. Guidelines for measurements of exhaled nitric oxide based on our experience are provided, as well as suggestions for the use of this technique as a new “airway inflammation test.” Pediatr Pulmonol. 1999; 28:282–296.

Extravasation rates and complications of intraosseous needles during gravity and pressure infusion

OBJECTIVE To compare the extravasation rates and insertion complications under gravity and 300 mm Hg (40 kPa) pressure infusion of threaded (SurFast and Sussmane-Raszynski intraosseous needles, Cook Critical Care, Bloomington, IN); and nonthreaded needles (16-gauge disposable intraosseous needle with 45 degrees trocar Cook Critical Care, Bloomington, IN; Jamshidi bone marrow needle; Baxter Health Care Corp, Valencia, CA). DESIGN A prospective, randomized study. SETTING An animal laboratory at a university center. SUBJECTS Five healthy mix breed piglets, weighing 15 to 15.5 kg. INTERVENTIONS Piglets were anesthetized and ventilated. Tibial, femoral, and humeral osseous sites were exposed by dissection of overlying tissue. All bleeding points were cauterized and oozing was prevented by sealing with cyanoacrylate. Intraosseous access devices then were inserted one at a time in random order and rated for difficulty of insertion. Normal saline solution was infused under gravity or 300 mm Hg (40 kPa) pressure. Extravasation rates then were calculated from the increase in weight of a gauze sponge wrapped tightly at the base of the needle during infusion. MEASUREMENTS AND MAIN RESULTS No significant (p > .05) differences in extravasation rates were noted among the different types of needles, either under gravity or pressure infusions. The Sussmane-Raszynski needle was significantly more difficult to insert than the others (rated difficult to insert and control in 16 of 34 attempts). Inadvertent penetration of both cortices occurred with nonthreaded needles only (three of 66 attempts). The SurFast needle provided greatest penetration control and was most resistant to accidental dislodgement. CONCLUSIONS Under ideal conditions, needle type does not influence extravasation rates. However, difficulty with insertion and penetration of both cortices occur commonly and may lead to extravasation during stressful emergency situations or when performed by unskilled personnel.

Comparison of pH and carbon dioxide tension values of central venous and intraosseous blood during changes in cardiac output

ObjectiveTo compare the pH and Pco2 values determined from of simultaneously corrected samples of central venous and intraosseous blood during sequential changes in cardiac output. DesignProspective, descriptive study. SettingAn animal laboratory in a university medical center. SubjectsFourteen mixed breed 4-wk-old piglets. InterventionsAnimals were anesthetized with ketamine hydrochloride and neuromuscular blockade was induced by the administration of pancuronium bromide. After endotracheal intubation and the institution of mechanical ventilation, a 4-Fr pulmonary artery catheter and a carotid artery cannula were inserted via a cutdown into the right neck of each piglet. A 16-gauge intraosseous needle was inserted into the anteromedial surface of the right tibia. Measurements and Main ResultsCentral venous and intraosseous blood gas samples were obtained simultaneously with thermodilution cardiac output measurements. Cardiac output measurements were as follows: during steady state (0.80 ± 0.14 L/min), after volume loading of 15 mL/kg (1.00 ± 0.25 L/min), after three successive bleeds of 15 mL/kg each at 30-min intervals (0.70 ± 0.28, 0.54 ± 0.22, and 0.43 ± 0.16 L/min, respectively) and at exsanguination (unrecordable). Paired t-tests demonstrated no significant differences in pH and Pco2 values between intraosseous and central venous samples under all study conditions. Limits of agreement for difference in Pco2 between sites, within the range of cardiac outputs studied, were −12.86 to 11.38 torr (-1.71 to 1.46 kPa) and for pH were −0.09 to 0.15. ConclusionsIntraosseous blood samples can be obtained without difficulty even during extreme hypovolemia. The pH and Pco2 values of intraosseous and central venous blood samples were similar under all study conditions. Intraosseous blood may be a useful alternative to central venous blood to assess tissue acid-base status during hemorrhagic shock and other low-flow states. (Crit Care Med 1994; 22:1010–1015)

Intraosseous and central venous blood acid-base relationship during cardiopulmonary resuscitation

Objective The objectives of this study were: 1) to determine whether obtaining intraosseous (IO) blood samples was practical during cardiopulmonary resuscitation (CPR), and 2) to compare the acid-base status (pH and partial pressure of CO2 (Pco2) of venous and IO blood during CPR. Design A prospective repeated measure study. Setting An animal laboratory at a university medical center. Interventions Nine mixed breed piglets (mean weight 43 kg) were anesthetized, tracheotomized, and placed on a ventilator (Siemens 900C Elema, Sweden). Placement of a pulmonary artery catheter was done via a surgical incision in the neck. An IO cannula was then placed in the tibial marrow cavity. The animals were positioned under a mechanical thumper (Thumper,™ Michigan Instruments, Grand Rapids, MI) for chest compressions. Blood gases were analyzed during steady state (baseline) after five minutes of ventricular fibrillation and during CPR at seven, nine, 11, 13, 15, and 18 minutes. Main results Blood samples for acid-base analysis were easily obtained from the IO sites during all sampling times. Mixed venous blood was slightly more acidic than IO blood, especially at 13, 15, and 18 minutes. However, there were no significant differences in pH and Pco2 values between IO and central venous (CV) gases at all time intervals except the Pco2. At nine minutes, a significant difference (P < 0.006) was found in Pco2 (59 ± 4 vs 47 ± 5 torr) for the CV versus IO sample, respectively. As the duration of CPR progressed, the differences in PCO2 between IO and CV sites were clinically relevant (though not statistically significant). Conclusion Obtaining blood from the IO site is practical during CPR. The divergence in values as CPR progresses suggests that, during longer periods of CPR, IO blood may reflect local acidosis and yield lower Pco2 and higher pH values that CV blood. This finding may limit the usefulness of IO blood to judge acid base status as CPR progresses.

Effect of oral arginine supplementation on exhaled nitric oxide concentration in sickle cell anemia and acute chest syndrome.

Introduction Decreased exhaled nitric oxide levels (FENO) have been described in patients with sickle cell disease (SCD) and a history of acute chest syndrome (ACS) when compared with non-ACS controls. Oral arginine supplementation has been shown to increase FENO in healthy participants, but its effect in SCD patients is not known. Objective To determine the effect of oral arginine intake on FENO in sickle cell patients with and without history of ACS, and in healthy controls. Hypothesis No differences in the FENO increase were seen in SCD patients with a history of ACS (ACS+) compared with healthy controls (HC) and SCD patients without history of ACS (ACS−). Materials and Methods ACS+ (n=6), ACS− (n=9), and HC (n=7) patients were studied. At baseline, and after the administration of escalating doses of oral L-arginine (0.1, 0.2, and 0.4 g/kg), serial measurements were made of the following: FENO, plasma concentrations of arginine, ornithine, citrulline, aspartate, glutamate, arginine/ornithine ratio, nitrite, nitrate, heart rate (HR), respiratory rate (RR), blood pressure (BP), oxygen saturation (SpO2), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC). Main Results At baseline, FENO did not differ among the groups. ACS− and ACS+ groups were deficient in arginine, and had decreased FEV1, FVC, and SaO2 when compared with HC patients. After arginine supplementation, FENO, arginine, ornithine, citrulline, nitrite, and the arginine/ornithine ratio increased similarly in all groups. Changes from baseline for HR, BP, SpO2, RR, FEV1, and FVC were minimal and similar in all groups. Conclusions In contrast to our earlier study, ACS+ patients had similar FENO values when compared with ACS− and HC patients. All SCD patients were arginine deficient at baseline and showed impairment in respiratory physiology when compared with HC patients. After arginine supplementation, FENO concentration increased in all groups to a similar degree, and lung function and physiologic parameters were minimally affected. The physiologic significance of alterations in FENO in SCD patients and its relationship to ACS predilection requires further delineation.

Growth hormone-binding protein levels: studies of children with short stature.

A high-affinity growth hormone-binding protein (GHBP) in serum is derived from the extracellular domain of the GH receptor. In an attempt to investigate the differences in GHBP levels in various conditions of poor growth, we measured GHBP levels by two methods--an Ultrogel chromatographic technique and a ligand-mediated immunofunctional assay (LIFA). The following three groups of children were studied: Turners syndrome (n = 7), idiopathic and/or familial short stature ([ISS] n = 15), and organic or idiopathic hypopituitarism (n = 19). All groups were similar in age (Turners syndrome, 10.1 +/- 0.9 years; ISS, 10.0 +/- 0.7; hypopituitarism, 11.5 +/- 1.0) and height SEM score (Turners syndrome, -2.9 +/- 0.3; ISS, -3.0 +/- 0.4; hypopituitarism, -2.3 +/- 0.4). Their values were compared with those values of GHBP in healthy controls of similar age. Immunofunctional assay values for GHBP were as follows: Turners syndrome, 235.4 +/- 26.0 pmol/L; ISS, 122.4 +/- 11.0; and hypopituitarism, 157.1 +/- 23.0. These results were significantly different in subjects with ISS and hypopituitarism as compared with a group of healthy controls between the ages of 9 and 12 years (N = 255; GHBP = 287.9 +/- 10.9 pMol/L; P < .001 compared with both ISS and hypopituitarism). Similar changes were found using Ultrogel chromatography. This difference in GHBP levels is still significant even when more stringent criteria are applied to define hypopituitarism (ie, peak GH responses to stimuli < 6.0 ng/mL, instead of < or = 10 ng/mL originally).(ABSTRACT TRUNCATED AT 250 WORDS)