Samples For Blood Gas Analysis Research Articles

Cardiopulmonary effects of epidurally administered xylazine in the horse

This study was designed to determine whether the epidural administration of an alpha2 agonist, xylazine, would produce measurable changes in arterial blood pressure, electrocardiographic (ECG) activity and arterial blood gas values in horses. Six horses were given each of four treatments: epidural xylazine, intravenous xylazine, epidural lidocaine and epidural saline. A carotid artery catheter was used to measure arterial blood pressure and to collect samples for blood gas analysis before treatment and at intervals post treatment. Heart rate, arterial pressures, ECG activity and respiratory rate were recorded at the same intervals. No significant changes were recorded between time intervals or between individual treatments. It was concluded that this method of xylazine administration to horses produced potent caudal analgesia without measurable cardiopulmonary effects.

Effect of separate hemidiaphragm contraction on left phrenic artery flow and O2 consumption

Phrenic arterial blood flow has been shown to increase during bilateral phrenic nerve stimulation (BPNS). However, the role of unilateral phrenic nerve stimulation [left (LPNS) or right (RPNS)] on the blood flow and O2 consumption of the contralateral hemidiaphragm is not known and is explored here. In six anesthetized, mechanically hyperventilated dogs, left phrenic arterial blood flow (Qlpha) was measured (Doppler technique). Supramaximal (10 V, 30 Hz, 0.25-ms duration) LPNS, RPNS, and BPNS at a pacing frequency 15/min and duty cycle of 0.50 were delivered in separate runs. Left hemidiaphragmatic blood samples for gas analyses were obtained by left phrenic venous cannulation. During RPNS, Qlpha and left hemidiaphragmatic O2 consumption (VO2ldi) did not change significantly compared with control. During LPNS and BPNS, there was a significant increase in Qlpha and VO2ldi (P less than 0.01). There was no significant difference in Qlpha and VO2ldi between LPNS and BPNS (P greater than 0.05). We conclude 1) that there is a complete independence of left-right hemidiaphragmatic circulation both at rest and during diaphragm pacing and 2) that during unilateral stimulation transdiaphragmatic pressure is not related to diaphragmatic blood flow.

Importance of correct handling of samples for the results of blood gas analysis.

The importance of correct handling of samples for blood gas analysis was studied in 100 patients. Sixty minutes storage in iced water lowered pH by 0.02 pH-units. Storage at room temperature caused considerable changes in PCO2 and PO2 (+0.45 kPa and -1.05 kPa). Air bubbles in the syringes increased PO2 if not expelled within 30 s. Thirty minutes storage with air trapped inside the syringe caused an increase in PO2 of 1.8 kPa and a decrease in PCO2 of 0.16 kPa. The use of plastic syringes induced significant changes in PCO2 and PO2, of which the latter (+1.0 kPa) may be clinically significant. The findings indicate that sample collection and storage must be guarded by strict rules in order to avoid false results.

Intravascular pH-ISFET, a method of the future

Since blood pH reflects the metabolic state as well as the functioning of the respiratory and circulatory systems, it appears to be one of the vital parameters that should be continuously monitored. The point to point measurement of pH by sampling has limitations, since results are available after some time only. A continuous pH signal is necessary in rapidly changing situations such as often occur during intensive treatment. The application of ion-selective field-effect transistor (ISFET) technology to intravascular pH measurement seemed attractive since these devices offer a short response time, are suitable to miniaturization and fabrication in large quantities, and have a low output impedance. The system was tested in dog experiments. Two to four pH-ISFET catheters were tested simultaneously in each dog. Arterial samples for blood-gas analysis with a Radiometer ABL2 system were taken during periods in which plasma-pH was stable. Clinical trials were performed in patients who were admitted to the intensive care unit after coronary artery bypass grafting. Testing the pH-ISFET system in dogs (N = 12) and comparing it with ABL2 measured samples (n = 132 with a pH range of 6.72-7.86), resulted in a delta pH (ISFET-ABL2) of 0.016 +/- 0.024 pH with a maximum deviation of 0.06. The clinical trials proved that the system is well-suited for monitoring intravascular pH in critically ill patients.

Cannulation of the Dorsal Radial Artery

Percutaneous cannulation of the radial artery is commonly performed to monitor arterial blood pressure and obtain arterial blood samples for blood gas analysis. The radial artery is usually entered on the volar aspect of the wrist. It is also possible to cannulate the radial artery on the dorsum of the hand, where it emerges from the anatomic snuffbox. Here the radial artery assumes a superficial location, passing beneath the tendon of the extensor pollicis longus and between the bases of the first and second metacarpals. This report reviews our experience with dorsal radial arterial cannulation.

The role of halothane and fentanyl in the production of balanced anaesthesia.

The aim of the study was to quantitate the degree of respiratory depression when tolerance of superficial nociception and of an endotracheal tube was achieved by supplementing N2O + O2 anaesthesia either with halothane alone or with halothane in combination with fentanyl. Eighty-four patients, matched into seven groups, were studied after induction of anaesthesia with thiopental (4 mg/kg) and suxamethonium (3 mg/kg) using the following supplementation: 0.8, 0.6, 0.4% halothane alone or 0.4, 0.2, 0% halothane with 0.5-2 micrograms/kg fentanyl. After 10 min administration of the anaesthetic mixture using manual intermittent positive pressure ventilation (IPPV) (end-tidal CO2 c. 5.5%), IPPV was discontinued and spontaneous respiration allowed to return. When the end-tidal CO2 had stabilized, samples for blood gas analysis were taken and superficial antinociception was tested by pinching an inguinal skin fold. Supplementation of an N2O + O2 mixture with 0.8% halothane without fentanyl or with 0.4% halothane with 0.5 microgram/kg fentanyl seemed to come closest to the optimum in producing tolerance of an endotracheal tube and of superficial nociception (in about 85% of cases with an increase in PCO2 to only 7 kPa.

Mixed venous and arterial pH: A comparison during hemorrhagic shock and hypothermia

Under normal conditions a linear relationship exists between venous and arterial pH values. However, with severe metabolic and hemodynamic stress this correlation has not been established. To evaluate this relationship, nine dogs were subjected to 60 minutes of hemorrhagic shock at a mean arterial pressure of 30 mm Hg and were then resuscitated. Seven dogs were rendered hypothermic by surface cooling. Serial arterial and mixed venous samples for blood gas analysis were obtained from the femoral artery, superior vena cava (SVC), right atrium (RA), and pulmonary artery (PA). There were no statistical differences between mixed venous pH values obtained from SVC, RA, and PA during any study time. The differences between arterial and mixed venous pH (AVpH) had a significant linear relationship (r greater than 0.90, P less than 0.01). The AVpH during hypothermia was +.03 to +.04 pH units. The greatest AVpH occurred during shock, and ranged from +.08 to +.20 pH units. During recovery AVpH was intermediate at +.04 to +.13. It appears that during hemorrhagic shock and moderate hypothermia, a significant relationship persists between mixed venous and arterial pH. The mixed venous sample can be obtained from the superior vena cava, right atrium, or pulmonary artery.

1347 STATISTICAL DOCUMENTATION THAT CONTINUOUS OXYGEN MONITORING IMPROVES PATIENT CARE

In a prospective controlled study, we used the Oximetrix(R) catheter oximeter in preterm infants with cardiopulmonary disease to determine if continuous measurement of arterial oxygenation offers any significant clinical advantages over conventional intermittent monitoring. Eleven study and 11 control infants were matched for gestational age, weight, hematocrit and similarity of disease. The mortality rate, need for a ventilator and the time in an FiO2 >.40 or >.70 were similar in both groups. The simultaneous measurement of saturation by the catheter oximeter and the Radiometer OSM2 bench device was compared. The correlation coefficent of 1039 data pairs was .97. In-vivo calibration was required in 60% of catheters in use 40 hours. The time before the first calibration was 18.3 ± 10.6 hours (mean ± S.D.). During the first 72 hours, 51% more blood samples for gas analysis were withdrawn from the control group (p=.012) and the number of blood samples obtained per hour during the catheter's lifetime was greater (p=.026). More blood transfusions were needed in the control group (p=.019). The PaO2 was greater than 100 mmHg 18.6% (control) and 8.4% (study) of the total hours the catheters were used for monitoring (p=.026). This study shows statistically significant evidence that the continuous measurement of arterial oxygenation using the Oximetrix(R) oximeter improves the management of infants with cardiopulmonary disease.

Superior Thyroid Artery Cannulation for Monitoring Carotid Artery Operation

Superior thyroid artery cannulation during carotid endarterectomy and coupling the cannula to a three-way stopcock with an anaeroid manometer allows the surgical team in the operating field to monitor mean pressures and to draw blood samples for gas analysis from the common, the internal, or the external carotid artery. The technique has been applied in 118 patients without related complications.

Ventricular Fibrillation Without Left Ventricular Venting: Observations in Humans

Pressures were measured in the heart and great vessels of 52 patients who underwent coronary revascularization. In 25 patients the left ventricle was vented during fibrillation; in the others a vent was not used. Samples for blood gas analysis were obtained twice during fibrillation from the aorta, left atrium, pulmonary artery, and right atrium. Left ventricular venting was found to be effective in keeping mean left heart pressures below 10 mm Hg, although temporary incompetence of the aortic valve or malfunction of the vent occasionally caused higher pressures. Vent use led to air embolism in the aorta in 16% of the patients. In the nonvented patients mean left heart pressures remained between 10 and 20 mm Hg. However, higher values were frequently observed. Blood gas analysis demonstrated that without venting, retrograde pulmonary flow occurred during fibrillation. No abnormality was encountered that could be related to nonventing.

Ear lobe blood samples for blood gas analysis at rest and during exercise

A technique is described for obtaining good samples of arterialized ear lobe blood both at rest and during exercise on a cycle ergometer. The method has been validated against simultaneously obtained arterial samples, and the accuracy for Pco 2 , Po 2 and pH has been found adequate for clinical and physiological investigations.

Ear lobe blood samples for blood gas analysis at rest and during exercise

A technique is described for obtaining good samples of arterialized ear lobe blood both at rest and during exercise on a cycle ergometer. The method has been validated against simultaneously obtained arterial samples, and the accuracy for Pco 2, Po 2 and pH has been found adequate for clinical and physiological investigations.