Objective: We try to answer the question of '' how much will (co2) of blood change if we keep the amount of fresh gases constant" the subject of the present study on patients in Tajrish hospital in winter 1998.Methods: This research was done on 80 adults in the age group of 15-65. Who was under goung a surgical operation of lung. This was clinical trial using double blind sequential method subjects in control group were giner inspirations (12/min) and 12 times in the first 30 minutes for those in test group and in both groups the PACO2 of blood was measured by the AVL system during the first 30 and 60 minutes. The amount of drug used before anesthesia and also the amount of anesthetic gases has been equal in both groups.Findings: The research outcome has shown that the amount of PACO2 was not changed at all in control group where as it has increased among the experimental subjects from 28.74±3.38 in the first half hour to 34.32 ±3.65 in the first hour. While paired t test showed that this 20% increase can be noticeable, statistics (p<0.001) and the changes of PACO2 in both groups also revealed to be clear and meaningful (p<0.001).Conclusion: The results have shown that increased respiratory rate increases the level of PACO2, although such increments would be considered normal.  

Background: End-tidal CO2 has a linear correlation with arterial pressure of CO2 in adults. Such relationship in critically ill pediatric patients is conflicting. We have studied this correlation in intubated patients of Mofid Pediatric Hospital, Tehran, Iran.Materials and methods: From 38 mechanically ventilated critically ill, intubated patients 68 pair samples of PACO2- PETCP2 were gathered. We used side stream capnograph before arterial sampling. This study were conducted from March 2006 until October 2007 in pediatric intensive care unit of Mofid Hospital.Results: Patients were 2.2±3 year old and 56% of them were girls. They were admitted due to neurologic, respiratory, hematology, cardiology or other causes. PETCO2 showed a strong correlation with PACO2. Linear regression analysis depicted following outcome: PETCO2=0.7 PACO2 (95% confidence interval: 0.56-0.79) +3.7 (95% confidence interval: 0.5-7.9) Those patients with a better respiratory condition (SpO2>85%) had a PACO2 - PETCO2 difference of 4±2 while in poor circumstances (SpO2<85%) this figure was 11±7.Conclusion: We recommende using capnograph for monitoring ventilation of intubated pediatric patients in intensive care units. Estimation of arterial CO2 pressure according to end-tidal CO2 depends on the pulmonary function. As the respiratory condition deteriorates PACO2-PETCO2 difference enlarges but the linear correlation remains.

Background: It is necessary to determine the value of PaO2 and PACO2 in COPD patients for diagnosis the severity of chronic bronchitis diseases and their separation from other diseases.For the diagnosis of COPD diseases and their separation from other diseases and for having a criterion for treatment with oxygen, we need to know the amount of Pao2 and PACO2 in patients; ABG is an invasive and difficult procedure.Materials and Methods: This cross sectional study was carried out on 118 consecutive patients with chronic bronchitis referring to Afshar hospital in Yazd in order to determine the correlation between spirometry FEV1 and ABG parameters.Results: The study population included 82 (69.5%) males and 36(30.5%) females with the mean age of 71.6±9 years. The mean FEV1 (% pred.) was 42.88±15.12, mean PaO2 was 55.31±13.51 mmHg and mean PACO2 was 51.64±10.56 mmHg. FEV1 was positively correlated with PaO2 (r=0.418, p<0.0001) and inversely correlated with PACO2 (r= -0.533, p<0.0001).Conclusion: One could establish a reliable equation indicating the correlation between FEV1 and PaO2 as well as PACO2 in patient with chronic bronchitis.

Background: The diagnosis of pulmonary embolism (PE) because of nonspecific clinical presentation remains as a challenge for emergency physicians. Arterial to end‑, tidal partial pressure of carbon dioxide (P(a‑, Et)CO2 ) gradient may be useful in the evaluation of PE. This aimed to define the diagnostic role of P(a‑, Et)CO2 gradient by sidestream capnography, as a noninvasive method, and D‑, dimer in patients with PE. Materials and Methods: Two hundred and three patients with chest pain or dyspnea who attend the hospital emergency ward were enrolled over a study period at a single academic center. PE was confirmed by multidetector computed tomography (MDCT) scans. PACO2, EtCO2, and D‑, dimer were measured within 24 h of MDCT by capnograph. Results: The combination of P(a‑, Et)CO2 gradient (cutoff >9. 2 ng/ml) and D‑, dimer (cutoff >3011 ng/ml) with sensitivity and specificity of 30. 2% and 87. 2% showed a significant diagnostic value in detecting PE (area under the curve = 0. 577, P = 0. 045) but not alone (P > 0. 05). Conclusion: As the results show, the combination of P(a‑, Et)CO2 gradient and D‑, dimer can show an acceptable diagnostic value in detecting PE, although it suggests further research on evaluating the diagnostic value of P(a‑, Et)CO2 gradient and combining it with other diagnostic criteria to achieve a definite and generalizable result.

Background: In patients under mechanical ventilation, the patient's position is one of the factors affecting the efficiency of respiratory gas exchange. The aim of this study was to compare the level of arterial blood gas pressure and the percentage of arterial oxygen saturation in the supine position with the lateral position in patients with ventilator-associated pneumonia. Methods: In a clinical trial study with a sample size of 50 patients with ischemic stroke under mechanical ventilation admitted to the intensive care unit of Kashani hospital affiliated to Shahrekord University of Medical Sciences, Shahrekord, Iran, in 2019 were selected using convenience sampling method. Oxygen saturation percentage was measured by a pulse oximeter in patients lying on their backs and then, on their sides for two hours,arterial blood pressure and carbon dioxide levels were measured with arterial blood sample by laboratory device, and recorded in the relevant checklist as well. Findings: In both supine and lateral positions, the mean arterial oxygen pressure and the percentage of hemoglobin oxygen saturation were not significantly different (P > 0. 050),while the arterial carbon dioxide pressure in the lateral position was significantly lower than the supine position (P = 0. 008). Conclusion: The lateral position has no significant effect on the improvement of arterial blood gases and oxygen saturation in patients with pneumonia due to mechanical ventilation,but has significantly reduce the pressure of carbon dioxide.

It is very important to know about ABG in order to evaluate the oxygenation potency of lungs especially in critically ill patients. Many factors such as geographical position do affect ABG. This cross-sectional study was done on 83 healthy young persons having no systemic or other kinds of diseases affecting arterial blood gases. Information on PH, Pao2, ao2, Spo2 and Spo2 were gathered from each person. The obtained results were statistically analyzed using t-test. The mean Pao2 and PACO2 were 111.77 and 41.49 mmHg respectively (see also tables). In the present study, special geographical position of Sari in the vicinity of the Caspian Sea has affected the abovementioned parameters, so that pao2 is much higher. Therefore a higher level of arterial oxygen is to be considered hypoxia in order to prevent the hypoxia risk.

Capnography is one of the most important monitoring that is recommended by American Society for Testing and Material in 1998 (ASTM98) for every patient under anesthesia.Usually sampling of expired gas in capnography commonly obtained from side or mid stream. Badgwell and et al recommended that sampling of expired gas for Capnography for patient under one year should be taken from distal end of endotracheal tube.In this study to determine accuracy of ventilation with modified Jackson Rees system, we studied 622 infants and children who were ventilated with this system. Expired gas for CO2 monitoring sampled at distal and proximal end of endotracheal tube and the arterial Pco2 (PACO2) simultaneously measured.In this paper we studied the accuracy of ventilation with modified Jackson Rees system in 62 infants and children. We sampled the expired gas for CO2 analysis from both proximal and distal of the endotracheal tube and measured PACO2 simultaneously.In our experience we found that PETCO2-d (distal end - tidal PCO2) was close to PACO2, but PETCO2-p(proximal end - tidal PCO2) was insignificantly greater than PACO2 especialy in infant who were less than 10kg. As we did not find any significant difference between measurement of PETCO2-d (distal end tidal PCO2) and PETCO2-p (proximal end tidal PC02), we suggest to measure PETC02-p instead of PETC02-d, in any infant less than 10kg and children weighting more than 10kg who Ventilated by modified Jackson Rees system.

Background: Carbon dioxide (CO2) is a by-product of cellular metabolism, which could be considered as a reflection of metabolism, circulation, and ventilation. Arterial blood gas analysis (ABG) is the gold standard of monitoring for CO2. However, is an expensive method leading to blood loss and iatrogenic anemia. In addition, each sample is only a snapshot view of the sampling moment. End-tidal CO2 (ETCO2) measurement gives a non-invasive and continuous monitoring of exhaled CO2. Therefore, this study aimed to validate the non-invasive CO2 measurement performed by nasal cannula and evaluate the correlation with partial pressure of arterial CO2 (PACO2 ) in neonates. Methods: This single-center observational study was conducted in the Neonatal Intensive Care Unit (NICU), Kasturba Hospital, Manipal, India. PACO2 was reported on routine ABG within a 15-minute interval of ABG sampling. Moreover, partial pressure of end-tidal carbon dioxide (PetCO2) was noted at continuous 30-sec intervals (i. e., 30, 60, 90, . . ., 180) up to 3 minutes. The values of PACO2 and PetCO2 were found to be correlated with Pearson correlation and were shown by scattered plot. Regression analysis was used to get the prediction equation and the variance. Results: A total of 70 samples were taken in the initial phase to study the correlation between PACO2 and measured PetCO2. Pearson correlation showed a moderate positive correlation (r= 0. 589) between PetCO2 and measured PACO2. Regression analysis demonstrated a variance of 33. 8% between the measured PetCO2 and PACO2, which was statistically significant (P<0. 001). A prediction equation was obtained for PACO2. In the final phase, 20 samples were recruited to standardize and validate the prediction equation. The PACO2 was calculated using the predicted equation and a new prediction equation was obtained. Conclusion: According to the findings of this study, there is a good correlation (r=0. 681) between the non-invasively measured PetCO2 and PACO2.