Comparative evaluation of central venous versus arterial blood sample for repetitive measurements in critically ill patients admitted in intensive care unit.
The analysis of arterial blood gases (ABG) plays a pivotal role in making correct diagnosis and deciding management strategies in critically ill patients.
The arterial blood gas analysis is one of the most important investigation for assessment of clinical oxygenation and acid-base status in critically ill patients. (3) It provides us with information about ventilation, oxygenation and acid-base status, the three closely interrelated physiological parameters, which maintain the pH homeostasis. The body is an active chemical reaction requiring a precise balance of acids and bases a measurement known as pH. (4)
The two main organs regulating the acid-base balance are lungs and kidneys. Looking at the gases that are measured it is easy to see how the lung is involved, bringing in oxygen and expelling carbon dioxide. This is known as respiratory metabolism. The kidney is important in metabolic control by actively regulating the dissolved C[O.sub.2] or bicarbonate which is in the plasma and is expelled through urine. The common parameters included in arterial blood gas analysis. (5,6) are: pH, PC[O.sub.2], P[O.sub.2], HC[O.sub.3], Hb. and Saturation.
Its correct interpretation and application necessitates the knowledge of basic applied physiology in relation to these parameters. This role can be well exemplified by considering the concept of respiratory failure. (7)
ABG is the only investigation, which can document, specify and quantitate the respiratory failure. High PaCO2, moderately low PaO2 and acidic pH indicate ventilatory failure and low PaCO2, low PaO2 and alkaline pH indicate primary oxygenation failure. The management plan will be ventilatory support in the former case and oxygen therapy in the latter case. Since ABG provides a rapid and accurate assessment of oxygenation, ventilation and acid-base status, the prerequisite for understanding and correctly interpreting ABG is knowledge of basic physiology in relation to ventilation, oxygenation and acid base status. (8)
Through this review an attempt has been made to formulate a comprehensive approach by first describing the basic physiology in relation to ABG, followed by stepwise approach to analyse ABG.
Overall, arterial line placement is considered a safe procedure with a rate of major complications less than 1%. (9) Arterial lines can be placed in multiple arteries, including the radial, ulnar, brachial, axillary, dorasalis pedis, posterior tibial and femoral. The most common site of cannulation is the radial artery, followed by the femoral artery. (10) the radial artery is the site of choice by many due to its ease of cannulation, consistent anatomy, and low rate of complications. (11) the femoral artery has the advantage of having a low risk of thrombosis, but overall a similar rate of complications.
Arterial blood gas (ABG) sampling is widely considered to be essential in the initial diagnostic evaluation of critically ill patients. ABG sampling is invasive, can be difficult but has an important role in the assessment of patients with severe respiratory and metabolic disease, in particular for accurate determination of pH.
Central Venous catheter has become an integral part in the management of critically ill patients being used for fluid administration, an important source of blood sample for chemical analysis and sampling, parenteral nutrition and central venous pressure determination and administration of drugs with high osmolality that cannot be given through peripheral veins and also provides a readily available and safe alternative to repetitive arterial blood gas analysis. (12) The traditional approach, which concentrates on arterial blood gas analysis only, may miss important aspects of oxygen delivery to tissues, especially in patients with poor perfusion. (13)
Assessing both the arterial blood and central venous samples should result in more efficient and higher quality care for critically ill patients. Although information about arterial blood gases is needed to assess pulmonary gas exchange, in presence of severe hypoperfusion, the hypercapnia and academia at the level of tissues are detected better in central venous blood. (14) Venous blood gas (VBG) analysis clearly does not replace ABG analysis in determining exact [Po.sub.2] status, and arterial puncture may still be required for invasive arterial BP monitoring, but given the well-accepted accuracy of pulse oximetry, VBG analysis may be a safer alternative to ABG analysis for determining acid-base status, reducing the need for frequent invasive arterial sampling. (15)
A few authors have expressed doubts the use of VBG values in lieu of arterial values. The aim of this study is to investigate the agreement between ABG and Central VBG samples for all commonly used parameters (pH, Pc[o.sub.2], Hb% saturation and bicarbonate) in a pathologically diverse ICU patient population.
AIMS AND OBJECTIVES: To evaluate the reliability of central venous blood gas monitoring as an alternative to arterial blood gas monitoring & to assess that the central venous catheter is convenient and reliable source of blood for repetitive measurement of pH, bicarbonate and PC[O.sub.2] in critically ill patients.
MATERIALS AND METHODS: After approval by institutional ethical committee and written informed consent from the attendants of patient on mechanical ventilation, this prospective study was conducted in the department of Anesthesiology and Critical Care at Government. Medical College, Srinagar. The study included 100 patients of either gender admitted in surgical intensive care unit between year 2012-2013 needing close monitoring and care in an effort to correct metabolic and respiratory derangements.
A critical ill patient is one at imminent risk of death, the severity of illness must be recognized early and appropriate measures taken promptly to assess, diagnose and manage the illness. Exclusion included patients with cardiac arrest or heart failure.
The Cases were divided in Four Groups which Constituted Major Admission in SICU of Shri Maharaja Hari Singh Hospital Srinagar:
Group I: Poisoning patients.
Group II: Trauma patients.
Group III: Major abdominal surgery patients.
Group IV: Hypovolemic shock patients and others.
All of these patients on mechanical ventilator support with different modes of ventilation with different fractional percentage of oxygen were closely observed and monitored for respiratory, cardiovascular, central nervous system, acid base balance and a complete investigation profile. Under all aseptic precautions arterial line was secured in these patients with 20-22g cannula either in the dorsalis pedis or radial artery, after ruling out any contraindication like bleeding, diathesis. Central venous cannulation was done into either the internal jugular, subclavian, basilica or cephalic vein with either a 16cm long 7Fr double or triple lumen polyurethane catheter or cavafix respectively accordingly to the technique described by Seldinger.
Proper placement of the catheter was confirmed by determining the observed length of catheter, insertion free respiratory excursion of the column of saline used for measuring CVP aspiration of blood and plain chest radiograph. After the insertion of central venous catheter, a sample of 5ml of blood was obtained from the distal port of the catheter in a 2 or 5ml syringe containing 1-2ml of heparinised saline after securing other ports to avoid dilution of obtained blood sample with infusion fluid or intravenous drug infusion. Alteration in lab results with a heparinised syringe 1-2ml of blood was collected from central line after reattaching the syringe to the CVP catheter and lowering the syringe below the level of CVP line which allowed the blood from the central line to flow into the syringe by its own pressure and eliminated any possibility of trapping of air bubbles.
After collecting the blood sample, the line was flushed with same blood containing heparinised saline syringe to avoid clot formation and line blockade. At the same time 1-5ml of arterial blood was collected in heparinised syringe and repeating the same steps to avoid line blockade. The arterial and venous samples were sent for blood gas analysis. The sampling parameters included in the study were: Ph, PC[O.sub.2] P[O.sub.2] HC[O.sub.2] Hb saturation the collected sample was stored on ice and sent for analysis without any delay. The analysis was done with GEM Premier 3000 analyser within 5mins of collection of blood samples.
PRINCIPLE OF PROCEDURE: THE GEM Premier 3000 analyser is a portable critical care system for rapid analysis of whole blood samples at the point of care. The instrument provides quantitative measurements of pH, blood gases, sodium, potassium, ionized calcium and hematocrit. The analyser uses potentiometric sensors to measure pC[O.sub.2] pH, [NA.sup.+] [K.sup.+] [Ca.sup.++] and amperometric sensors to measure pO2 concentrations. Blood conductivity is used to measure hematocrit.
STATISTICAL ANALYSIS: The whole data was assimilated in the form of a master chart. The demographical data was analysed by using student 't' test and ANOVA whereas Pearson correlation and Bland Altman plots were used for analyzing the results obtained for comparison of central venous and arterial blood gases. The power of study was 90% with 95% confidence limit. The analysis of the data was performed by using SPSS computer program (Statistical Package for Social Sciences, SPSS Inc. Chicago, USA) version 20.0 and Medcalc.
OBSERVATIONS & RESULTS: Demographic features of overall cases were as follows: Maximum age of patients 60 years, Minimum age of patients 20 years, The mean age of patients 43.12 [+ or -] 13.37, The median age=45
There was insignificant difference in the distribution of age in years between the four groups.
There was a significant difference (p=0.015) in distribution of sex in four groups
There were overall 42 males and 58 females:
In group I: There were 7 males and 12 females
In group II: There were 12 males and 3 females
In group III: There were 12 males and 28 females
In group IV: There were 11 males and 15 females.
Statistically there was insignificant difference in FiO2 among all groups.
Statistically there was insignificant difference in VT among all groups (p-value = 0.747)
There was insignificant difference in respiratory rate among the four groups (p-value 0.852).
Mode 1--Volume control mode and Mode II--Pressure control mode.
Statistically there was highly significant difference in the distribution of ventillatory mode in each group.
There is high degree of positive correlation 0.979 between pH of arterial and pH of venous and is statistically significant.
There is high degree of positive correlation of 0.926 in PC[O.sub.2] between arterial and venous samples and is statistically significant.
There is positive correlation of 0.259 in P[O.sub.2] between arterial and venous samples and is statistically significant.
There is high degree of positive correlation of 0.955 in HC[O.sub.3] for arterial and venous samples and is statistically significant.
DISCUSSION: This study was carried out in the Postgraduate Department of Anesthesiology and Critical Care Medicine, Government Medical College and associated hospitals Srinagar over a period of one year (2012-2013).
One hundred patients were selected for the study including:
Group 1: Poisoning patients-19.
Group II: Trauma patients-15.
Group III: Major abdominal surgery patients-40.
Group IV: Hypovolemic shock patients and others-26.
Aim of the study was to evaluate the comparison of venous and arterial blood gas values and to evaluate the role of central venous blood gas analysis as an alternative to arterial blood gas analysis. Central venous catheter has an important role in the management of critically ill patients being used in measurement of Central venous pressure, administration of drugs and IV fluids and forms a part of usual protocol in the management of critically ill patients. Role of central venous blood gas analysis began to be identified in early 60's when many workers expressed their experience with the assessment of central venous blood gas values in different sets of patients but only a few had compared it with arterial blood gas values and attempted to draw an agreement between the two methods.
The possibility of using central venous blood rather than arterial blood for acid base analysis has been investigated by many researchers and has been a matter of considerable discussion with difference in opinion for various parameters obtained.
The studies of Weil. (16) and Zahn. (6) concluded that central venous blood mirrors the arterial blood pH and PCO2 values but did not agree upon the reliability with which the central venous blood may be used for analysis whereas the study of Sutton. (17) and co-workers suggested that the central venous blood gas analysis is reliable as a screening procedure only.
The study of Barrie Phillips. (18) concluded that central venous blood is a reliable and practical substitute to arterial blood gas analysis. Even our study observed highly significant correlation between arterial and central venous pH with a correlation coefficient of 0.979. Similarly there was a highly significant correlation between arterial and venous PC[O.sub.2] with a correlation coefficient of 0.926.
Some workers have observed that pH values of the two samples correlate better is noncardiac arrest than in patients with cardiorespiratory arrest. A possible explanation for this can be that in arrested patients there is a complete loss of cardiac and respiratory function thus the pH of blood signifies the difference between severe metabolic acidosis produced by the tissues and the buffering action of blood. The buffering action of lungs and kidneys does not play a role since its acid excreting rate is very slow and this may also be lost because of hypoperfusion.
The varying degree of loss of lung function and of alkali reserve in arrested patient's results in arterial to central venous correlation unlike in non-arrested patients.
The findings of our study are similar to observations made by other workers as well the results of which has been highlighted and compared with present study. Brasheer (19) conducted a study to devise a relationship between arterial and venous HC[O.sub.3]--values. The correlation between arterial and venous HC[O.sub.3]--was significant. They presented various equations for predicting arterial HC[O.sub.3]-. The study concluded that venous C[O.sub.2] has little direct use but when venous C[O.sub.2] is abnormal arterial ABG should be obtained.
Steinberg JJ. (20) et al also conducted a study to determine the reliability of central venous blood pH and PC[O.sub.2] utilizing regression equation and correlation coefficient methods. Thus study concluded that central venous blood gas analysis would be safe and suitable alternative and more than adequately described the acid base status of the patients. This study included only forty five patients with cardiothoracic procedures.
Parameters Present study J. J. Steinberg pH a-pH cv 0.979 0.882 PCO2A-PCO2V 0.926 0.798 Parameters J. J. Steinberg Present Study pHa range 7.29-7.59 6.794-7.562 pHv range 7.24-7.48 6.787-7.511 (r) 0.6443 0.979 PaC[O.sub.2] range 20.7-46.1 19.8-66.0 pvC[O.sub.2] range 30.0-46.1 25.1-69.8 (r) 0.539 0.926 (r) = correlation coefficient
The observations of Adrogue. (14) quite closely match our observations. He concluded that both arterial and central venous blood samples are needed to assess acid base status in patients with hemodynamic compromise, the hypercapnia and academia at the tissue level are detected better in central venous blood.
The prospective study carried out by Batra Y.K. (21) on patients with various abdominal surgical conditions closely match our observations in evaluating the role of central venous blood gas sampling as an alternative to arterial blood gas sampling.
Our observation as well as our scatter diagram shows a low correlation for P[O.sub.2] but a high correlation for pH, PC[O.sub.2] and HC[O.sub.3]--as shown by study of Batra Y.K.
Richard Treger. (15) et al. also did a prospective study to assess the agreement between arterial and central VBG measurements in medical ICU.
Parameters Present Study Richard Treger's pHa-pHcv 0.979 0.945 PCO2A-pco2v 0.926 0.883 Hco3A-HCO3 cv 0.955 0.950
There was great similarity in correlation coefficients for pH,PC[O.sub.2] HC[O.sub.3] in our study and study done by Richard Treger. (15) Thus a number of studies have suggested agreement between AVG and VBG values, although most of the previous studies were limited by specific patient group samples (e.g. patients with diabetic ketoacidosis) or analysis of only one or some parameters rather than all commonly used parameters (e.g. pH,PCo2 and bicarbonate) A few authors even expressed doubts about the use of VBG values in lieu of arterial values. The aim of this study was to investigate the agreement between ABG and central VBG samples for all commonly used parameters (pH, Pco2 PO2 Hb, saturation and bicarbonate) in a pathologically diverse ICU patient population.
SUMMARY AND CONCLUSION: The purpose of present study was to evaluate the reliability of central venous blood gas monitoring as an alternative to arterial blood gas monitoring and the assess that the central venous catheter is convenient and reliable source of blood for repetitive measurement of pH bicarbonate and PCO2 in critically ill patients admitted in surgical intensive care unit (SICU).
We took one hundred patients who required ABG analysis between 20-60 years of age. The cases were divided in four groups which constituted major admissions in SICU in one year.
Out of one hundred patients for the study there were 19 Poisoning patients, 15 Trauma patients, 40 Major abdominal surgery patients, 26 Hypovolemic shock patients and others. The mean age of patients was 43.12 [+ or -] 13.37 yrs. The median age of patients was 45. There was over all 42 males and 58 females
There was statistically insignificant difference in age, respiratory rate, tidal volume among all groups, though there was significant difference in distribution of age and various modes of ventilation.
Central Venous Blood Drawn within 5 min of an ABG Measurement and the Samples Analyzed Immediately on Automated ABG Analyzer were Compared:
1. Bland Altman plots demonstrated a high degree of agreement between the two corresponding sets of measurements of arterial and venous blood with coefficient of correlation 0.979 for pH.
2. The coefficient of correlation was highly positive i.e.; 0.926 for PC[O.sub.2] which is statistically significant.
3. The coefficient of correlation was highly positive i.e.; 0.955 for HC[O.sub.3]--which is statistically significant.
4. There was also positive correlation for saturation between arterial and venous blood i.e. 0.57 with clinically acceptable difference and is statistically significant.
5. The difference in pO2 measurements was however higher with correlation coefficient of 0.259 although the arterial saturation and finger oximetry reveals a good degree of agreement with clinically acceptable bias.
1. Venous blood gas (VBG) analysis clearly does not replace ABG analysis in determining exact pO2 status and arterial puncture may still be required for invasive arterial BP monitoring.
2. Although the difference in the blood gas parameters obtained from arterial and venous samples was statistically significant but with positive correlation and regression plots obtained, venous samples can be used as an alternative to arterial samples depending on the significant positive correlation values obtained for each parameter separately.
3. Given the well accepted accuracy of pulse oximetry, VBG analysis may be a safer alternative to ABG analysis for determining acid-base status, reducing the need for frequent invasive arterial sampling thus avoiding time consuming and complicated procedure of arterial cannulation in patients requiring prolonged mechanical ventilation in surgical Intensive Care Unit.
(1.) Definition of critically ill patients. American Association of Critical Care Nurses. www.aacn.org/wd/publishing/content/ pressroom/about critical approachg. pcm.
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(3.) Barthwal MS. Analysis of arterial blood gases-A comprehensive approach. JAPI 2004; VOL. 52: 573.
(4.) Siggaard-Andersen O, Fogh-Andersen N. Base excess or buffer base (Strong ion difference) as measure of a non-respiratory acid-base disturbance. Acta Anaesthesiol Scand Suppl 1995; 107:123-8.
(5.) Richard A theye M.D., Gerald F Touhy M.D. The value of venous oxygen levels during general anaesthesia. Anaesthesiology 1965; Vol.26.
(6.) Richard L Zahn, M.D. and Max H Weil. M.D., Ph.D. Los angeles. Central venous blood for monitoring ph, PCO2 in critically ill patients. Journal of Cardiovascular Surgery Vol. 52, No.1 July 1966.
(7.) Brooks D, Wynn V. Use of venous blood for pH and Carbon--dioxide studies especially in respiratory failure and during anaesthesia. Lancet. 1959 Jan 31; 1(7066):227-230. [pubmed].
(8.) Lev. II Curriculum Rev. 6/09 1 30 an article from the American Thoracic Society, "Guidelines for the Evaluation of Impairment/ Disability in Patients with Asthma.
(9.) Scheer B, Perel A, Pfeiffer UJ. Clinical review: complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine. Crit Care. Jun 2002; 6(3): 199-204. [Medline].
(10.) Milzma D, Janchar T. Arterial puncture and cannulation. In: Roberts JR, Hedges JR. Clinical Procedures in Emergency Medicine, 4th. Philidelphia: W.B. Saunders; 2004:384-400.
(11.) Brzezinski M, Luisetti T, London MJ. Radial artery cannulation: a comprehensive review of recent anatomic and physiologic investigations. Anesth Analg. Dec 2009; 109(6):1763-81. [Medline].
(12.) Blood gas analysis--definition of blood gas analysis in the Medical dictionary-by the Free Online Medical Dictionary, Thesaurus and Encyclopedia.htm.
(13.) Vet Clin North Am Small Anim Pract. 2002 Sep; 32(5):1031-48. Louisville Veterinary Specialty and Emergency Services, 12905 Shelbyville Road, Suite 3, Louisville, KY 40243, USA.
(14.) Adrogue Horacio J. M.D., Rashad M. Nabil M.D., Gorin Arnold B. M.D., joseph Yacoub, M.D., and Madias Nicolaos E., M.D.N. Engl J Med 1989; 320:1312-1316 May 18, 1989 Assessing Acid--Base Status in Circulatory Failure.
(15.) Richard Treger, Agreement between central Venous and Arterial Blood Gas Measurements in the Intensive Care Unit. CJASN March 2010 vol. 5 no. 3 390-394.
(16.) Weil MH, Rackow EC, Trevino R, Grundler W, Falk JL, Griffel MI. Difference in acid-base state between venous and arterial blood during cardiopulmonary resuscitation. N Engl J Med. 1986 Jul 17; 315(3):153-6.
(17.) Sutton R.N. M.D. Pennsylvania, R.F. Wilson M. D. Temple, F.A.C.S., A.J. Walt M.B. Cape Town, M.S. Minn., F.R.C.S., F.R.C.S.C., F.A.C.S. differences in acid-base levels and oxygen--saturation between central venous and arterial blood. The Lancet, Volume 290, Issue 7519, Pages 748-751, 7 October 1967.
(18.) Barrie Phillips, M.D. A Comparison of Central Venous and Arterial Blood Gas Values in the critically III. Annals of internal medicine 1969 April vol 70 No.4.
(19.) Brashear RE, Oei TO, Rhodes ML, Futty DE, Hostetler ML Relationship between arterial and venous bicarbonate values. [Journal Article] Arch Intern Med 1979 Apr; 139(4):440-2.
(20.) Steinberg JJ, Harken AH. The central venous catheter in the assay of acid base status. Surg Gynecol Obstet. 1981 Feb; 152(2):221-2
(21.) Batra, YK and Banerjee, D and Khanna SL., (1995) Role of central venous blood gas in monitoring of critically ill surgical patients. Journal of Anaesthesiology: Clinical Pharmacology, 11 (1). Pp.37-42. ISSN 0970-9185.
Rukhsana Najeeb , Nisha Yadav , Abraq Asma , Mohamad Ommid , Farhana Bashir , Aamil Hameem , Nusrat Jehan , Mubasher Ahmad 
[1.] Rukhsana Najeeb
[2.] Nisha Yadav
[3.] Abraq Asma
[4.] Mohamad Ommid
[5.] Farhana Bashir
[6.] Aamil Hameem
[7.] Nusrat Jehan
[8.] Mubasher Ahmad
PARTICULARS OF CONTRIBUTORS:
[1.] Professor, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[2.] Resident, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[3.] Lecturer, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[4.] Assistant Professor, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[5.] Senior Resident, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[6.] Senior Resident, Department of Anaesthesiology and Critical Care, Lady Hardinge Medical College, Delhi.
[7.] Assistant Professor, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
[8.] Lecturer, Department of Anaesthesiology and Critical Care, Government Medical College, Srinagar.
FINANCIAL OR OTHER COMPETING INTERESTS: None
NAME ADDRESS EMAIL ID OF THE CORRESPONDING AUTHOR:
Rukhsana Najeeb, Professor, Department of Anaesthesiology and Critical Care, Post Box: 659, GPO, Srinagar-190001, Jammu and Kashmir.
Date of Submission: 23/07/2015. Date of Peer Review: 24/07/2015. Date of Acceptance: 05/08/2015. Date of Publishing: 12/08/2015.
Table 1: Distribution of age (years) in different diagnosis Diagnosis No. of Cases Mean SD P-value Remarks I 19 38.47 12.213 II 15 39.2 15.086 III 40 45.77 12.694 0.138 Not sig. IV 26 44.77 13.498 Total 100 43.12 13.368 Table 2: Distribution of sex in different diagnosis Diagnosis Male Female Total No. of cases Count % age Count % age I 7 36.80% 12 63.20% 19 II 12 80.00% 3 20.00% 15 III 12 30.00% 28 70.00% 40 IV 11 42.30% 15 57.70% 26 Total 42 42.00% 58 58.00% 100 [chi square] = 11.465 D.F. = 3 P-value = 0.009 Table 3: Comparison of FiO2 in different diagnosis Diagnosis No. of Cases Mean SD P-value Remarks I 19 51.05 11.616 II 15 56.00 14.041 0.252 Not sig. III 40 50.75 9.971 IV 26 56.54 11.763 Table 4: Comparison of tidal volume in different diagnosis Diagnosis No. of Cases Mean SD P-value Remarks I 19 565.79 47.295 II 15 576.67 59.362 0.747 Not sig. III 40 572.5 45.22 IV 26 561.54 51.59 Table 5: Comparison of respiratory rate in different diagnosis Diagnosis No. of Cases Mean SD P-value Remarks I 19 11.63 1.739 II 15 12.73 3.515 0.852 Not Sig. III 40 12.38 3.801 IV 26 12.58 5.777 Table 6: Comparison of mode in over all cases Group Mode 1 % age Mode II % age Total I 13 68.40% 6 31.60% 19 II 5 33.30% 10 66.70% 15 III 33 82.50% 7 17.50% 40 IV 20 76.90% 6 23.10% 26 Total 71 71.00% 29 29.00% 1000 Chi-square = 13.410 d.f. = 3 p.value = = 0.004 Table 7: Comparison of pH in method 1 (Arterial) and method II (Venous) Study N Mean SD Range Method I 100 7.39 0.11 6.794-7.562 Method II 100 7.35 0.11 6.787-7.511 Co-efficient of Study Correlation P-value Remark Method I 0.979 <0.001 HS Method II Table 8: Comparison of PaCO2 in method 1 (Arterial) and method II (Venous) Study N Mean SD Range Method I 100 35.53 9.08 19.8-66.0 Method II 100 41.12 9.67 25.1-69.8 Co-efficient of Study Correlation P-value Remarks Method I 0.926 <0.001 HS Method II Table 9: Comparison of pO2 in method 1 (Arterial) and method II (Venous) Study N Mean SD Range Method I 100 117 49.6 46.9-370.2 Method II 100 45.4 10.4 19.4-91.7 Co-efficient of Study Correlation P-value Remarks Method I 0.259 <0.001 HS Method II Table 10: Comparison of HCO3 in method 1 (Arterial) and method II (Venous) Study N Mean SD Range Method I 100 21.11 4.97 6.2-33.8 Method II 100 22.71 5.12 6.8-34.4 Co-efficient of Study Correlation P-value Remarks Method I 0.955 <0.001 HS Method II Table 11: Comparison of Sp[O.sub.2] in method 1 (Arterial) and method II (Venous) Study N Mean SD Range Method I 100 96.77 3.85 74.0-99.8 Method II 100 76.9 10.3 46.0-96.8 Co-efficient of Study Correlation P-value Remarks Method I <0.001 HS Method II 9.57
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|Title Annotation:||ORIGINAL ARTICLE|
|Author:||Najeeb, Rukhsana; Yadav, Nisha; Asma, Abraq; Ommid, Mohamad; Bashir, Farhana; Hameem, Aamil; Jehan,|
|Publication:||Journal of Evolution of Medical and Dental Sciences|
|Article Type:||Medical condition overview|
|Date:||Aug 13, 2015|
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