Effects of salbutamol delivery from a metered dose inhaler versus jet nebulizer on dynamic lung mechanics in very preterm infants with chronic lung disease

Treatment of chronic lung disease of prematurity requires effective aerosol delivery of different therapeutic agents. Aerosols can be generated by a metered dose inhaler (MDI) or a jet nebulizer. An MDI combined with a spacer device is easier to use and avoids undesirable effects noted in conjunction with jet nebulization. We compared the clinical effectiveness of 200 micrograms (2 puffs) salbutamol delivered from an MDI in conjunction with a valved spacer device (Aerochamber), and 600 micrograms given via jet nebulizer (PariBaby) on 2 consecutive days, the order being randomized. Thirteen spontaneously breathing very preterm infants [mean (SD) gestational age 27.2 (1.8) weeks; birth weight 0.90 (0.34) kg] were studied at a corrected age of 37 (2.3) weeks. Mean (SD) study weight was 1.83 (0.38) kg. Dynamic lung compliance and resistance were determined from measurements of flows, volumes, and transpulmonary pressures, using a pneumotachometer and a small esophageal microtransducer catheter before and 20 min after salbutamol application. Baseline values before salbutamol administration were similar on both occasions: the mean (SD) compliance was 7.7 (3.0) mL.kPa-1.kg-1 pre-MDI plus-spacer and 8.4 (3.1) pre-jet nebulizer; the resistance was 10.4 (4.0) kPa.L-1.s pre-MDI plus-spacer and 9.7 (3.4) pre-jet nebulizer. Following salbutamol, compliance did not change significantly with either MDI plus spacer or jet nebulizer. Resistance fall significantly with MDI plus spacer (mean -2.2; 99.9% CI -0.35, -4.35) and jet nebulizer (-2.4; 99% CI -0.39, -4.42). We conclude that even in small preterm infants 200 micrograms salbutamol via MDI plus spacer improves dynamic resistance as effectively as 600 micrograms via jet nebulizer and may therefore be a preferable mode of aarosol administration.     

Clinical and endoscopic predictors of histological oesophagitis in infants

Therapeutic aerosols pay an increasing role in the treatment of equine respiratory disorders. This route of delivery permits concentration of significant amounts of drugs at the site of action without unwanted high systemic concentration and resultant side effects. The efficiency of such a topical therapy depends on the quantity of inhaled drugs deposited in the lungs and, for some drugs, on the proportion retained in specific parts of the lungs. The objective of this study was to define and to compare quantitative (dose deposited) and qualitative (regional distribution) deposition of an aerosol in the equine lungs, using either a ultrasonic nebuliser (UN) currently used in human medicine or a high pressure jet nebuliser (JN) especially developed for the equine species. This comparison was possible owing to gamma-scintigraphy, a noninvasive technique ideally suited to give information about both total and regional deposition of inhaled drugs in the respiratory tract. The quantitative study did not point out any difference between the 2 systems concerning the activity released from the nebuliser proportionally to the initial loaded dose (mean +/- s.d. 45.95 +/- 4.93% for the UN vs. 46.47 +/- 8.49% for the JN). By contrast, the percentage of the dose released reaching the lungs was significantly lower with the UN compared to the JN (5.09 +/- 0.66% vs. 7.35 +/- 1.96%). The qualitative analysis did not show any significant difference in size of aerosol deposition image between the 2 nebulisers. However peripheral deposition was significantly higher with JN compared to UN. In conclusion, both nebulisers may be used for aerosol therapy in the equine species. The ultrasonic and pneumatic nebulisation achieved drug deposition in the peripheral part of the lungs (i.e. small airways and lung parenchyma).     

Nebulisation of surfactants in an animal model of neonatal respiratory distress

AIMS: To evaluate pulmonary deposition and gas exchange following nebulisation of two surfactants by either a jet or an ultrasonic nebuliser. METHOD: After bronchoalveolar lavage (BAL), 19 rabbits were ventilated in four groups. Group A1 (n = 5) and A2 (n = 6) received Technetium-99m labelled Exosurf, and groups B1 (n = 4) and B2 (n = 4) received radiolabelled Survanta. Groups A1 and B1 received jet nebuliser therapy, whereas groups A2 and B2 received ultrasonic nebuliser. Pulmonary deposition, distribution, and blood gases were determined. RESULTS: Pulmonary deposition as per cent of initial dose and mg lipid) was 0.28(0.10)% or 0.59(0.21) mg in group A1, 1.05(0.23)% or 2.21(0.48) mg in group A2, 0.08(0.02)% or 0.30(0.08) mg in group B1, and 0.09(0.02)% or 0.34(0.08) mg in group B2. Deposition in group A2 was greater than in other groups (p = 0.001). Group A2 showed a small improvement in blood gases. CONCLUSIONS: Even the highest deposition--ultrasonic nebuliser with Exosurf--achieved limited clinical effect. The aerosol route is currently not effective for surfactant treatment.     

Transcutaneous oxygen and carbon dioxide during treatment of critical limb ischemia with iloprost, a prostacyclin derivative

The effect of intravenous iloprost treatment (median rate: 1.6; range 1-2 ng/kg/min; 6 h daily over 4 weeks) on transcutaneous pO2 and pCO2 was studied in 8 patients with bilateral peripheral obstructive arterial disease and monolateral critical limb ischemia. Tensiometric determinations were obtained at both metatarsi in the supine and dependent position. In critically ischemic limbs, supine transcutaneous p)2 changed erratically during iloprost treatment, increasing in only three out of eight lower limbs. At variance with its inconsistent behavior in the supine position, dependent pO2 increased during drug administration (p<0.02). Transcutaneous pCO2 was unchanged by iloprost. In the contralateral, non-symptomatic limb, both supine and dependent pO2 values were increased by the drug, suggesting that systemic hemodynamic changes may participate in its effect on transcutaneous gas tension, even at infusion rates clinically titrated to avoid evident changes in blood pressure and heart rate.     

Serological cross-reactions between Coxiella burnetii and Legionella micdadei

PURPOSE: The bronchodilator effect of salbutamol formulated in hydrofluoroalkane-134a (HFA-134a), a chlorofluorocarbon (CFC)-free propellant for metered dose inhalation (MDI) devices, was compared with that of salbutamol formulated in CFC in anesthetized dogs. METHODS: Bronchospasms were induced by the intravenous injection of histamine, and bronchial resistance was measured by the method of Konzett and Rossler. RESULTS: While the placebo vehicles (HFA-134a and CFC propellants) had no significant effect on histamine-induced bronchospasms, the salbutamol/HFA-134a and salbutamol/CFC MDI formulations had equivalent dose-related inhibitory effects. CONCLUSIONS: These data indicated that salbutamol formulated in HFA-134a and that in CFC propellant are bioequivalent.     

A review and economic evaluation of bronchodilator delivery methods in hospitalized patients

BACKGROUND: Bronchodilator delivery by metered dose inhaler (MDI) to treat airflow obstruction is considered to be less expensive and as effective as nebulized therapy. OBJECTIVES: To document the utilization of bronchodilator delivery methods in a tertiary care Canadian university teaching hospital and to perform an economic evaluation. METHODS: A prospective 6-week audit of 4 preselected hospital wards (respiratory, thoracic surgery, general surgery, and a general internal medicine clinical teaching unit) and a cost-minimization economic evaluation were performed. Bronchodilator (salbutamol and ipratropium bromide) doses, frequency, and delivery methods, either MDI or wet nebulizer (WN), were recorded for 95 patients treated with aerosolized bronchodilators. Direct costs for medications and hourly wages including benefits and equipment were obtained. Time and motion studies identified time allocated to MDI and WN delivery. We used sensitivity analyses to test assumptions that could significantly affect treatment costs, especially assumptions about medications, labor, and spacer devices. Costs are expressed in Canadian dollars (Can$1 = US$0.75). RESULTS: Sixty-seven patients (70.5%) were treated with WN, 6 (6.3%) with MDI, and 22 (23.2%) with both WN and MDI. Self-administration of salbutamol by MDI was the least expensive: $1.27 for 200-microgram doses and $1.73 for 400-microgram doses compared with $2.62 for a 2.5-mg dose delivered by WN. The difference in cost between equivalent treatments (400-microgram MDI vs 2.5-mg WN) is only $0.89. Sensitivity analyses showed that MDI was the least expensive therapy when self-administration was possible and for all levels of supervision if more than 4 minutes was needed to administer a WN treatment. CONCLUSIONS: Bronchodilator delivery by WN is commonly prescribed for hospitalized patients despite evidence for equivalency of effect using MDI and in the absence of substitution protocols. Previous studies have estimated a far greater cost differential based on unrealistic labor estimates. We found that supervision of patients using MDIs minimized the differential cost between WN and MDI therapy and that cost savings are maximal in patients who can self-administer MDI therapy. Methodologically sound economic evaluations can better identify true cost savings and variables that need further study.     

Gas tensions in cardiac lymph as a reflection of the interstitial space of the heart

The purpose of this study was to determine the feasibility of measuring partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and pH in cardiac lymph and to evaluate the relationship of these parameters to comparable measurements in arterial and coronary sinus blood in the normal heart under various respiratory conditions. In four anesthetized open-chest dogs, the principal cardiac lymphatic as well as the femoral artery and coronary sinus were cannulated. Ventilation was varied by changing oxygen concentration, tidal volume, and respiratory rate. PO2, pCO2, and pH were measured in the cardiac lymph, arterial blood, and coronary sinus blood after each change in ventilation. For pH and pCO2, good correlations were observed between the arterial blood and cardiac lymph, arterial blood and coronary sinus blood, and coronary sinus blood and cardiac lymph. The correlation between the pO2 measured in the arterial blood and the pO2 measured in the cardiac lymph was not as strong, and this may have been related to difficulty achieving a steady state. Gas tensions (pO2, pCO2, and pH) can be measured in cardiac lymph and may provide a window to the interstitial compartment of the heart. This is an additional tool for the laboratory study of ischemia and other forms of heart disease.     

Home nebuliser use in children with asthma in two Scottish Health Board Areas

OBJECTIVE: To audit the use of home nebulisers in children with asthma. DESIGN: Postal questionnaire. SETTING: Two Health Board Areas in Central Scotland--one large industrialised city, one mixed urban and rural. SUBJECTS: 297 children with asthma. MEASURES EVALUATED: Initial supply and technical support for the compressor. EDUCATION: Pattern of drug usage. SYMPTOM CONTROL: Monitoring and treatment of acute attacks. RESULTS: The full burden of the home nebulised therapy is not being met by the NHS. Supply and servicing arrangements for home nebuliser therapy were poorly organised. Chronic asthma symptoms did not appear to be optimally controlled on present medication, with 61% reporting sleep disturbance in the previous three months. About 20% of parents admitted that they would give nebulised bronchodilator therapy more frequently than the recommended 3 to 4 hourly. CONCLUSION: Re-organisation of resources and arrangements could improve the service and bring it in line with recognised standards of care.     

Respiratory response to salbutamol (albuterol) in ventilator-dependent infants with chronic lung disease: pressurized aerosol delivery versus intravenous injection

OBJECTIVE: To compare the effects of intravenously injected with inhaled salbutamol in ventilator dependent infants with chronic lung disease (CLD). DESIGN: Prospective randomized study which each patient served as his/her own control. SETTING: Multidisciplinary neonatal and pediatric ICU. PATIENTS: 8 ventilator dependent premature infants with CLD. INTERVENTIONS: Salbutamol, 10 micrograms/kg was given intravenously, and 10-19 h later, twice 100 micrograms as pressurized aerosol, or vice versa, sequence randomized. The pressurized aerosol was delivered by a metered dose inhaler into a newly developed aerosol holding chamber, integrated into the inspiratory limb of the patient circuit. Respiratory system mechanics were assessed by the single breath occlusion method before and 10 and 60 min after drug administration. MEASUREMENTS AND RESULTS: Compliance improved significantly after intravenous injection (0.48 +/- 0.18 to 0.67 +/- 0.16, p < 0.01 and 0.59 +/- 0.23 ml/cmH2O/kg, NS, (mean +/- 1 SD) and after inhalation (0.46 +/- 0.19 to 0.64 +/- 0.32, p < 0.01 and 0.56 +/- 0.31 ml/cmH2O/kg, NS). Resistance decreased after iv. use (0.38 +/- 0.17 to 0.25 +/- 0.11, p < 0.001 and 0.25 +/- 0.10 cmH2O/ml/s, NS) and after inhalation (0.35 +/- 0.12 to 0.27 +/- 0.09, p < 0.01 and 0.28 +/- 0.12 cmH2O/ml/s, NS). Heart rate increased significantly after both routes of application, whereas mean arterial pressure, respirator settings, FIO2, transcutaneous SO2 and capillary PCO2 did not change. CONCLUSIONS: Inhaled and intravenous salbutamol improves pulmonary mechanics to the same extent with comparable side effects, and may therefore be used to facilitate weaning from respirators.     

Postmarketing surveillance study of a non-chlorofluorocarbon inhaler according to the safety assessment of marketed medicines guidelines

OBJECTIVE: To evaluate the safety of a non-chlorofluorocarbon metered dose salbutamol inhaler. DESIGN: This was a postmarketing surveillance study, conducted under formal guidelines for company sponsored safety assessment of marketed medicines (SAMM). A non-randomised, non-interventional, observational design compared patients prescribed metered doses of salbutamol delivered by inhalers using either hydrofluoroalkane or chlorofluorocarbon as the propellant. Follow up was three months. SETTING: 646 general practices throughout the United Kingdom. SUBJECTS: 6614 patients with obstructive airways disease (1667 patient years of exposure). MAIN OUTCOME MEASURES: Proportions of patients who were: admitted to hospital for respiratory diseases, reported adverse side effects, or withdrew because of adverse affects. RESULTS: There were no significant differences between the hydrofluoroalkane (HFA 134a) and chlorofluorocarbon inhaler groups in relation to the proportions of patients admitted to hospital for respiratory diseases (odds ratio 0.75; 95% confidence interval 0.51 to 1.08) or the proportions who reported adverse events (1.01; 0.88 to 1.17). However, more patients using the hydrofluoroalkane inhaler than the chlorofluorocarbon inhaler withdrew because of adverse events (3.8% and 0.9% respectively). CONCLUSION: The hydrofluoroalkane inhaler was as safe as the chlorofluorocarbon inhaler when judged by hospital admissions and adverse affects. The study design successfully fulfilled the recommendations of the guidelines. Differences between postmarketing surveillance studies and randomised clinical trials in assessing safety were identified. These may lead to difficulties in the design of postmarketing surveillance studies.     

Sources of error in the pre-analytical phase of blood gas analysis

Analysis of blood gases and blood pH yield important information in many situations of clinical emergencies. We report on a patient in whom pre-analytic errors in blood gas and blood pH measurements resulted in unnecessary further investigations. We therefore studied various pre-analytic sources of error in blood pH and blood gas analysis. Delay in sample processing for more than one hour resulted in an increase of pO2 and pCO2 and a decrease of pH. Excess sodium heparin solution as an anticoagulant (> or = 10% of total volume) led to a significant decrease of pH and pCO2 and to an increase of pO2. Air bubbles (10% of total volume) left in the syringe for 10 min significantly increased pO2. For accurate estimations of pO2, pCO2 and pH, it is necessary to keep the heparin solution below 10% of total volume, to expel all air bubbles from the syringe and to process the blood sample within one hour. Instructions to medical staff on handling blood samples for blood gas analysis should include these possible sources of errors.     

Predictors of mortality and the provision of dialysis in patients with acute tubular necrosis. The Auriculin Anaritide Acute Renal Failure Study Group

BACKGROUND: Improvement of angina pectoris symptoms after cholesterol lowering has raised questions as to the underlying mechanisms. METHODS: Rabbit experiment: We compared arterial blood samples from New Zealand White cholesterol-supplemented rabbits (n = 6) with nonsupplemented rabbit samples (n = 4) in a closed-loop circulation diffusion system. The pH and partial pressures of oxygen (pO2) and carbon dioxide (pCO2) were measured continuously. The samples were first oxygen (O2) saturated (pO2, 160 mm Hg; pCO2, 4 mm Hg) and then desaturated in 100% nitrogen. Cholesterol levels were determined in whole blood, plasma (P Chol), red blood cells (RBCs), and RBC membranes. Human experiment: We exposed quadruple desaturated venous blood samples (n = 4) with P Chol levels of 87 to 400 mg/dL in a gas exchanger to capillary gas conditions (pO2, 23 mm Hg; pCO2, 46 mm Hg). After 15 minutes we performed blood gas analyses and compared our results to baseline values. RESULTS: In the rabbit experiment the cholesterol-supplemented group as compared to the control group showed higher plasma pO2 levels during the saturation phase and lower plasma pO2 levels during the desaturation phase. It also had a markedly increased RBC membrane cholesterol content: 121 +/- 3 (standard error of the mean [SEM]) mg/dL versus 22 +/- 1.7 mg/dL in the control group (P < .05). This barrier to RBC membrane O2 diffusion caused delayed O2 entry into the RBCs during saturation, with a higher plasma pO2, and delayed O2 release from the RBCs during desaturation, with a lower plasma pO2. In the human experiment the P Chol level was inversely correlated with the percentage change of O2 content in milliliters of O2 per deciliter of blood (P < .05). CONCLUSIONS: Increased RBC membrane cholesterol in hypercholesterolemia appears to decrease the transmembrane O2 diffusion rate.     

Valproate reduces intake of alcoholic beverage among rats

SETTING: University of Malaya Medical Centre, Kuala Lumpur, Malaysia. OBJECTIVE: To assess the awareness of the ozone layer and the acceptance of the new non-chlorofluorocarbon (CFC) propellant hydrofluoroalkane 134a salbutamol pressurised metered dose inhaler (MDI) Airomir among asthmatic patients. DESIGN: A total of 113 consecutive asthmatic patients aged 12 years and above from the out- and in-patient services of the hospital were interviewed using a questionnaire. RESULTS: Sixty-five per cent of the patients were aware of the existence of the ozone layer, 23% that CFCs play a role in ozone depletion, and only 10% that current MDIs contained CFCs. All the patients felt that pressurised MDIs should be made CFC-free after they had considered the role of CFCs in the destruction of the ozone layer. Eighty-one per cent of 94 patients who preferred the Airomir inhaler over a multi-dose dry powder inhaler for administering bronchodilator medications were willing to switch to the new inhaler once it became available on the market. CONCLUSION: Awareness of the damaging effect of CFCs on the ozone layer among asthmatic patients would encourage them to change to an ozone-friendly, CFC-free pressurised MDI.     

Comparison of jet and ultrasonic nebulizer pulmonary aerosol deposition during mechanical ventilation

Increased delivery of aerosol to a model lung (attached to a mechanical ventilator) has been demonstrated with an ultrasonic nebulizer as compared to a jet nebulizer. This study examined whether the increased aerosol deposition with an ultrasonic nebulizer could also be demonstrated in vivo. Seven patients (6 male and 1 female) were studied during mechanical ventilalion (Siemens Servo 900C, Middlesex, UK) after open heart surgery. Two studies were performed in each patient. In the first study, aerosol was delivered via a Siemens Servo 945 nebulizer system (high setting) driving a System 22 Acorn jet nebulizer (Medic-Aid, Sussex, UK) containing 3 mL (99m)technetium-labelled human serum albumin (99mTc-HSA) (50 microg; activity 74 MBq). In the second study, a DP100 ultrasonic nebulizer (DP Medical, Meylan, France) containing 12 mL 99mTc-HSA (50 microg; activity 185 MBq) was used. Pulmonary deposition was quantified using a gamma camera. The humidification of the circuit and the ventilator settings were kept constant according to the patient's clinical requirements. The total lung aerosol deposition (mean+/-SD), as a percentage of initial nebulizer activity, was greater using the ultrasonic nebulizer than using the jet nebulizer (53+/-1.4 vs 2.3+/-0.9%; p<0.002). The ultrasonic nebulizer was also associated with a reduction in the time required to complete nebulization (9 vs 21 min, respectively) (p<0.0001). Use of the DP100 ultrasonic nebulizer more than doubled lung deposition compared with the System 22 jet nebulizers in mechanically-ventilated patients. Their efficiency, speed of drug delivery, and compatibility with mechanical ventilator circuits make ultrasonic nebulizers potentially attractive for use during mechanical ventilation.     

District nebuliser compressor service: reliability and costs

BACKGROUND: There is little information on the costs of maintaining a district nebuliser compressor service. This retrospective study examines the issue, reliability, and maintenance costs of electrical compressors to assist the prediction of future costs, taking into account recent safety legislation. METHODS: Records of issue, repair, and replacement for the period 1982-91 were reviewed. The current policy of repairing and replacing as necessary, and three other theoretical costings, were considered. RESULTS: The number of compressors being issued is increasing. Repaired compressors are less reliable and frequency of repair is a function of compressor age. The current policy is the most cost effective. CONCLUSIONS: To repair and replace nebuliser compressors as necessary is the most economical policy under the present terms offered by the manufacturers, but changes in safety legislation will affect the provision of such services.     

Changes of some physicochemical parameters of gas exchange in aqueous humor of rabbits during treatment of experimental uveitis

PURPOSE: To evaluate the usefulness of some parameters of the aqueous humor: pH, pO2 (oxygen pressure), pCO2 (carbon dioxide pressure) and HCO3- concentration in the diagnosis of uveitis. Changes of these parameters following conventional treatment and cryotherapy have also been investigated. MATERIAL AND METHOD: We used 40 grey rabbits (weighing 2.5-3.0 kg). Uveitis was evoked by intravitreal injection of 5 mg of animal albumin. Cryotherapy was performed by transconjunctival, quintuple cryoapplication (30 s) over ciliary body. Samples of aqueous humor were collected 6, 12, 24 and 48 hours after albumin injection. pH, pO2, pCO2 values and HCO3- concentration were determined using Astrup microanalyser. RESULTS: Parameters of aqueous humor, especially pH, pCO2 and HCO3- turned out to be fairly sensitive indicators reflecting the natural history of experimental uveitis. Cryotherapy characteristically modulates the pH, pCO2 and HCO3- values in the anterior chamber. CONCLUSIONS: We came to the conclusion that monitoring of these parameters may give some important information about the intensity of the course of uveitis and the influence of the treatment. Normalisation of the values usually parallels clinical improvement.     

Aerosol therapy

Aerosol therapy plays a major role in the diagnosis and treatment of various lung diseases. The aim of inhalation therapy is to deposit a reproducible and adequate dose of a specific drug to the airways, in order to achieve a high, local, clinical effect while avoiding serious systemic side effects. To achieve this goal, it is therefore important to have an efficient inhalation device to deliver different medications. However, the currently available therapeutic inhalation devices (nebuliser, pressurised metered-dose inhaler and dry powder inhaler) are not very efficient in aerosol delivery and have several disadvantages. Inhalation devices can be assessed by in vitro studies, filter studies and radiolabelled deposition studies. Several radiolabelled deposition studies have shown that nebulisers and pressurised metered-dose inhalers are not very efficient in aerosol delivery. In children, before 1997, only 0.5% to 15% of the total nebulised or actuated dose from a nebuliser or pressurised metered-dose inhaler actually reached the lungs. These numbers were somewhat improved in adults, 30% of the total nebulised or actuated dose reaching the airways. Aerosol therapy with dry powder inhalers was the most efficient before 1997, 30% of the total dose being deposited in the lungs of adults and children. In 1997, new developments in pressurised metered-dose inhalers much improved their efficiency in aerosol delivery. Lung deposition can be increased by up to 60% with use of a non-electrostatic holding chamber and/or a pressurised metered-dose inhaler with a hydrofluoroalkane propellant possessing superior aerosol characteristics. Several studies comparing the clinical efficiency of different inhalation devices have shown that the choice of an optimal inhalation device is crucial. In addition to the aerosol characteristics, ventilation parameters and airway morphology have an important bearing on deposition patterns. These parameters may be greatly influenced by the patient's acceptance of a specific inhalation device and therefore determine the choice of the device used. It is important for the clinical impact to develop more efficient inhalation devices, which need to be assessed for use in different age groups. These devices should be cheap, easy to use, portable, usable with all medications and environmentally safe.     

The i-STAT analyzer. A new, hand-held device for the bedside determination of hematocrit, blood gases, and electrolytes

Exact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. Depending on the capabilities of a hospital's central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. METHODS: Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. Accuracy was judged according to the national quality standard, which requires test results to lie within the 95% confidence interval of conventional tests. RESULTS: Each blood specimen was analysed: erroneous results or technical failures did not occur. Measurement of one set of i-STAT values required 2.5 min. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K; 0.86 for Na; 0.99 for pH; 0.98 for pCO2; 0.99 for pO2; 0.93 for HCO3; 0.93 for BE; 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb; and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l); pH (by 0.01); pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values < 200 mmHg); Hb (by 1.6 g/dl); Hb/CPB (by 0.8 g/dl); and Hct (by 6.5%, but were met for Hct/CPB values). All other tests fulfilled the required standards. CONCLUSION: This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. That the nationally required quality standards for Ca, pH, and Hb were not met is not of importance because the measured deviation was too small to have clinical relevance. When analysing diluted blood with a low Hct and low oncotic pressure, it is important to activate the analyser's correction algorithm "CPB", because the obtained results will then comply with the required accuracy.     

Immunohistochemical demonstration of androgen receptors in human salivary glands

One hundred and eighty-one children with asthma were entered into a randomized, controlled, crossover study comparing sodium cromoglycate via a metered dose inhaler (MDI) and a breath-actuated inhaler (Autohaler). There were no significant differences in pulmonary function tests (FEV1, FVC, PFER), symptom scores and bronchodilator use between the two devices. However both patients' and clinicians' opinions of sodium cromoglycate effectiveness were significantly better (P < 0.01) for the Autohaler. Autohaler was also thought to be easier to use (P < 0.001) and better for co-ordination of actuation with inhalation (P < 0.001). The Autohaler is as efficacious as the metered dose inhaler used by good co-ordinators. It seems to be the significantly better device with respect to ease of use, actuation and co-ordination which may aid compliance.     

Use of serotonin for treatment of patients with diabetic angiopathies

In 26 patients (female 11, males--15) with diabetic angiopathy (necrosis of the foot or toes) local measurement of pO2 by transcutaneous mode was carried out before and during introduction of serotonine adipinate. Simultaneously with evaluation of pO2 in 14 patients electromyography (EMG) was made. Serotonine adipinate was introduced intravenously with a speed of 5.0-10.0 mg per hour. In this group mean age of the patients made up 57.4 years, mean values of initial pO2 25.6 mm Hg, and mean indices of pO2 at the moment of serotonine treatment 38.5 mm Hg. Average increase of pO2 during serotonine infusion was registered as 50.4% in comparison with mean initial data. In all 14 patients, who underwent simultaneous measurement of pO2 and registration of EMG, reinforcement of electrical activity of smooth muscles (SM) of various intensity and increase in tissue pO2 were detected. Improvement of microcirculation (increase of transcutaneous pO2, reinforcement of electrical activity of SM as a result of serotonine introduction) evidences that functional and morphological changes of serotonine receptors of SM are involead in genesis of diabetic angiopathy. The data obtained showed that in diabetes mellitus, besides insulin deficiency, insufficiency of such an endogenous factor as serotonine duclops. Thus, serotonin should be used for prophylaxis and treatment of diabetic angiopathies.