Continuous intra-jugular venous blood-gas monitoring with the Paratrend 7 during hypothermic cardiopulmonary bypass

We measured the accuracy of the continuous intra-vascular blood-gasmonitoring system (Paratrend 7, PT7) placed in the jugular venousbulb in 18 adult patients having cardiac or aortic surgery withhypothermic cardiopulmonary bypass (CPB). After induction ofanaesthesia, a PT7 sensor was inserted through a 20-gauge venouscatheter into the right jugular venous bulb. Blood samples weredrawn from the venous catheter and measured with a blood gasanalyser (BGA). Five to eight paired measurements using thePT7 and blood samples were made per patient, and bias and precisionwere calculated for each patient using the Bland-Altman method.The ranges for the blood sample measurements were: pH 7.12 to7.59, PCO₂ 3.7 to 9.6 kPa, PO₂ 3.5 to 16.0 kPa, oxygen saturation40 to 99%, bicarbonate 18.6 to 34.4 mmol l^–1, and baseexcess –7.8 to 12.5 mmol l^–1. Bias and precisionvalues were 0.014/0.071 for pH, 0/0.90 kPa for PCO₂, and –0.16/1.18kPa for PO₂. These values were comparable with those previouslymade on arterial blood. However, precision for oxygen saturationin each patient varied 2.3 to 23.6% (95% CI: 6.3 to 12.9%),which was unsatisfactory for clinical measurements. Deep hypothermia(     

Continuous arterial blood gas monitoring during bilateral sequential lung transplantation.

OBJECTIVE: To determine the accuracy and clinical utility of a continuous arterial blood gas (ABG) monitor during lung transplantation. DESIGN: Prospective, observational cohort study. SETTING: University hospital. PARTICIPANTS: Eleven patients undergoing bilateral sequential lung transplantation (BSLTx). INTERVENTIONS: Repeated ABG sampling. MEASUREMENTS AND MAIN RESULTS: Agreement was measured by the bias (limits of agreement): pH, 0.006 (-0.10 to 0.10); PaO2, -22 mmHg (-130 to 86 mmHg); and PaCO2, -1.6 mmHg (-13.4 to 10.2 mmHg). Sensitivity and specificity of the Paratrend 7 (Biomedical Sensors, Ltd, Malvern, PA) PaO2 measurements (to detect PaO2 < 100 mmHg) were 84.6% and 97.6%, respectively. CONCLUSION: Continuous ABG monitoring with the Paratrend 7 shows sufficiently good agreement with laboratory blood gas analysis during BSLTx and thus is a convenient alternative to intermittent laboratory blood gas measurement. Because of the potential for significant (and sometimes rapid) acid-base disturbances, continuous ABG monitoring may have a role during most lung transplantation procedures.     

A comparison of anaesthetic tensions in arterial blood and oxygenator exhaust gas during cardiopulmonary bypass

This study evaluates the usefulness of the analysis of gas sampled from the exhaust port of a membrane oxygenator in the estimation of anaesthetic tension in arterial blood. Sixty-seven arterial blood samples were drawn from patients undergoing hypothermic cardiopulmonary bypass with anaesthesia maintained by either isoflurane or desflurane. Anaesthetic tensions in the oxygenator exhaust gas were measured using an infrared analyser and in arterial blood using a two-stage headspace technique with a gas chromatograph. Both measurement systems were calibrated with the same standard gas mixtures. There was no difference in anaesthetic tension measured in arterial blood and gas leaving the oxygenator exhaust (isoflurane: n = 29, range: 0.3-0.8%, 95% limits of agreement: -0.08% to 0.09%; desflurane: n = 38, range: 1.5-5.4%; 95% limits of agreement -0.65% to 0.58%). We conclude that anaesthetic tensions in arterial blood can be accurately monitored by analysis of the gas emerging from the exhaust port of a membrane oxygenator.     

Continuous intra-arterial blood gas monitoring during oesophagectomy

Purpose

To evaluate the clinical usefulness of the continuous intra-arterial blood gas (CIABG) monitoring system, Paratrend 7?, during differential lung ventilation (DLV) in 12 patients undergoing oesophagectomy.

Methods

Anaesthesia was induced with propofol and was maintained with isoflurane, oxygen and air, supplemented by an epidural infusion of mepivacaine. Arterial samples for estimation of blood gases (ABG) were taken just before and 5, 10, 20, 30, 60, and 90 min after the pleura was opened. The pH, PO₂, and PCO₂ values displayed by the CIABG monitor, which were recorded prior to the arterial blood sampling, were compared with the results of ABG analysis.

Results

Eighty-four blood samples were obtained and the ranges for the measured variables were PCO₂ 24.8–57.4 mmHg, PO₂ 47–449 mmHg, and pH 7.30–7.49. The correlation between CIABG and ABG measurements was strong and significant (r values: PCO₂ 0.80, PO₂ 0.93, pH 0.94). The overall bias ± precision between the two methods was PCO₂ 0.9 ± 3.1 mmHg, PO₂ ?1 ± 40 mmHg, %PO₂ 0.8 ± 21.6 %, pH 0.00 ± 0.02. For PO₂ values < 150 mmHg, the biases ± precision were PO₂ ?5 ± 17 mmHg, %PO₂ ?2.1 ± 20.7%.

Conclusion

The agreement between CIABG and ABG measurements was better for PCO₂ and pH than for PO₂. Although the CIABG system is clinically useful for monitoring trends in blood gas changes, the accuracy of the PO₂ value may be unacceptable during DLV because the error is theoretically < 34 mmHg with 95% reliability in the clinically important range of PO₂, < 150 mmHg.

Objectif

Évaluer l’utilité clinique du système de monitorage continu des gaz sanguins par voie intra-artérielle (CIABG), Paratrend 7®, durant la ventilation à un poumon chez 12 patients subissant une oesophagectomie.

Méthodes

Après induction au propofol, l’anesthésie a été maintenue à l’isoflurane avec air et oxygène, complétée d’une infusion péridurale de mépivacaïne. Des gaz artériels (ABG) ont été prélevés immédiatement avant l’ouverture de la plèvre de même qu’à 5, 10, 20, 30, 60 et 90 min après son ouverture. Les valeurs du pH, PO₂ et PCO₂ indiquées par le système de monitorage (CIABG), et enregistrées avant l’échantillonnage artériel, ont été comparées avec celles des gaz artériels.

Résultats

Quatre-vingt-quatre échantillons sanguins ont été prélevés et l’éventail des variables mesurées a été: PCO₂ 24,8-57,4 mmHg, PO₂ 47–449 mmHg et pH 7,30-7,49. La corrélation entre les mesures effectuées par CIABG et celles effectuées par ABG a été très bonne et significative (valeurs de r: PCO₂ 0,8, PO2 0,93, pH 0,94). La tendance globale ± la précision entre les deux méthodes a été: PCO₂ 0,9 ± 3,1 mmHg, PO₂ ?1 ± 40 mmHg, % PO₂ 0,8 ± 21,6%, pH 0,00 ± 0,02. Pour des valeurs de PO₂< 150 mmHg, la tendance ± la précision ont été pour la PO₂ de ?5 ± 17 mmHg et pour le % PO₂ de ?2,1 ± 20,7%.

Conclusion

La concordance entre les mesures par CIABG et celles par ABG était meilleure pour la PCO₂ et le pH que pour la PO₂. Même si le système CIABG est utile cliniquement pour la surveillance des tendances de variations des gaz sanguins, la précision des valeurs de PO₂ peut être inacceptable durant la ventilation à un poumon parce que l’erreur est théoriquement de < 34 mmHg avec 95% de fiabilité dans la gamme de PO₂ cliniquement importante soit < 150 mmHg.     

The influence of blood flow and arterial blood pressure during cardiopulmonary bypass on deltoid muscle gas tensions and body temperature after bypass.

The results of this study demonstrate that skeletal muscle perfusion during bypass requires high flows and mean arterial pressures and that use of vasopressors during bypass impairs skeletal muscle blood flow. Our findings also indicate that skeletal muscle perfusion during bypass decreases metabolic acidosis after operation and prevents decreases in body temperature and poor skeletal muscle blood flow in the post-bypass and early postoperative periods. Our results suggest that perfusing to maintain normal Pmo2 during extracorporeal circulation is superior to more conventional techniques of conducting bypass.     

Continuous monitoring of mixed venous oxygen saturation during aortofemoral bypass grafting

Measurement of mixed venous oxygen saturation (SvO2) may be helpful in the care of critically ill patients. Serial determinations of SvO2 give an index of the relationship between oxygen delivery and tissue oxygen consumption. Continuous monitoring of SvO2 is now readily available with the Shaw Oximetrix pulmonary artery catheter (Oximetrix Inc., Mountain View, CA). This system has provided useful information in the high risk cardiac surgery patient. Continuous monitoring of mixed venous saturation may be helpful in high risk or critically ill general and peripheral vascular surgery patients both in the intensive care unit and in the operating room. The following clinical report is presented to illustrate the usefulness of continuous SvO2 monitoring in a high risk vascular surgery patient.     

Continuous intra-arterial blood gas monitoring during thoracic surgery

Purpose. This study was undertaken to assess the clinical usefulness of a continuous intra-arterial blood gas (CIABG) monitoring system, Paratrend 7, during thoracic surgery. Methods. A sensor of the CIABG monitoring system was inserted into the radial artery in 50 patients. During one-lung/differential lung ventilation, arterial blood samples for estimation of blood gases (ABG) were taken every 45–90 min or when clinically needed. The Pco₂, Po₂, and pH values displayed by the CIABG monitor were recorded prior to arterial blood sampling and were compared with the results of ABG analysis. The mean (bias) and the standard deviation (precision) of the differences were calculated from the data for each parameter. Results. Ninety-four blood samples were obtained. The correlation between CIABG and ABG measurements was strong for each parameter: r = 0.83 (Pco₂), 0.89 (Po₂), 0.74 (pH). The bias ± precision between the two methods was 0.4 ± 3.0 mmHg for Pco₂, −6 ± 47 mmHg for Po₂, −1.2 ± 27.4% for Po₂ and −0.01 ± 0.04 for pH. For Po₂ values <150 mmHg, the bias ± precision was 1 ± 28 mmHg. Conclusion. The agreement between CIABG and ABG measurements was better for Pco₂ and pH than for Po₂. The Po₂ value displayed on the CIABG monitor may not always be reliable during thoracic surgical procedures. Received: July 26, 1999 / Accepted: January 13, 2000     

Massive arterial air embolism during cardiopulmonary bypass

Massive arterial air embolism occurred in two patients during 1250 open heart operations. Emergency measures led to complete recovery in both cases. Flow reversal, hypothermia and anti-oedema measures may be adequate in some clinical situations for total recovery after this catastrophic accident.     

The effects of continuous blood gas monitoring during cardiopulmonary bypass: a prospective, randomized study--Part II

The impact of blood gas management during cardiopulmonary bypass (CPB) on patient care has not been examined and remains controversial. The purpose of this study was to determine whether precise blood gas management during CPB influences patient outcome. Fifty-nine patients were enrolled in an Institutional Review Board-approved, prospective, randomized study. An in-line blood gas monitor (CDI 500) was placed into the arterial and venous lines for all patients. Blood gas monitoring in the control group was managed by intermittent sampling (every 20-30 min), while the treatment group was managed with continuous monitoring. Blood gas control and measured parameters were as follows: pH 7.40 +/- 0.05, PaCO2 40 +/- 5 mmHg, PaO2 200 +/- 50 mmHg. The treatment group had the CDI 500 guide clinical decisions. Compared to the control group, the treatment group consisted of significantly more diabetic (7% vs. 47%, p < or = 0.001), renal failure (3% vs. 13%, p < or = 0.01), and chronic obstructive pulmonary disease patients (7% vs. 20%, p < or = 0.01). Internal thoracic artery utilization was higher in treatment patients than control patients (67% vs. 95%, p < or = 0.02). No other differences existed in demographic, pharmacological, surgical, or anesthetic parameters. In the perioperative period, the control group required antiarrythmic support more frequently than the treatment group (10% vs. 0%, p < or = 0.05). Compared to the control group, the treatment group required antiarrythmic (18% vs. 10%, p < or = 0.05) and cardiac glycoside therapy (11% vs. 0%, p < or = 0.05) less frequently in the postoperative period. Although treatment patients required less intraoperative pacing and cardioversion and spent less time on mechanical ventilation, in the intensive care unit (ICU), and in the hospital than control patients, statistical significance was not achieved. In conclusion, the use of continuous, in-line blood gas monitoring resulted in improvement in a number of postoperative outcome variables, although ICU and hospital stay was not effected.     

The effects of continuous blood gas monitoring during cardiopulmonary bypass: a prospective, randomized study--Part I

The use of continuous in-line blood gas management (CILBGM) is steeped in controversy concerning its potential utility and impact on patient outcomes. The purpose of this study was to determine whether the use of CILBGM results in improved quality of patient care. Fifty-nine patients were enrolled in a Institutional Review Board-approved, prospective, randomized study. An in-line blood gas monitor (CDI 500) was placed into the arterial and venous lines for all patients. Blood gas monitoring in the control group was managed by intermittent sampling (every 20-30 min), while the treatment group was managed with continuous monitoring. There were no differences between groups in preoperative, surgical, anesthetic, or perfusion variables. The accuracy of the in-line monitor was comparable to laboratory analysis for arterial blood gas parameters (N = 160; pH bias = 0.00; PaCO2 bias = -1.1 mmHg; and PaO2 bias = 0.7 mmHg). There was less deviation from target values (pH = 7.40, PaCO2 = 40 mmHg, PaO2 = 150-200 mmHg) when in-line monitoring was used versus intermittent sampling (N = 784; pH deviation = 0.05 +/- 0.03 vs. 0.03 +/- 0.01, p < 0.0001; PaCO2 deviation = 4.0 +/- 2.9 mmHg vs. 2.0 +/- 0.9 mmHg, p < 0.0001; and PaO2 deviation = 22.7 +/- 16.9 mmHg vs. 11.7 +/- 8.3 mmHg, p < 0.0001). In conclusion, the results of part I of this study demonstrate that the use of CILBGM results in more accurate blood gas management during CPB.     

Urethral blood circulation during cardiopulmonary bypass

The haemodynamic changes induced by extracorporeal circulation (ECC) are thought to be important in the induction of urethral strictures in open heart surgery when indwelling latex catheters are used. In the present study, 6 piglets were cannulated and connected to extracorporeal perfusion apparatus. Pump flows correlated with human ECC values with non-haemic prime were used. The mucosal and submucosal blood circulation in the urethra reduced by 66% during ECC (P less than 0.05). The brain and hepatic arterial flows increased. A significant reduction was seen in renal blood circulation. The changes in the urethral blood circulation during ECC correlated with previous findings. The reduced wash out levels of chemicals leaching from the indwelling latex catheters as a result of reduced local blood circulation are the main trigger for the induction of urethral strictures during ECC and in other shock-like circulatory disturbances in the human body.     

The effects of venous cannulation technique and cardioplegia type on plasma potassium concentration and arterial blood pressure during cardiopulmonary bypass.

The cannulation method and cardioplegia solution used during cardiopulmonary bypass (CPB) may both influence plasma potassium concentrations ([K+]) and mean arterial blood pressure (MAP). Bi-caval or right atrial cannulation methods are routinely used in conjunction with crystalloid or blood cardioplegia. We investigated the influence of cannulation method and cardioplegia solutions on plasma [K+] and MAP during cardiopulmonary bypass. Sixty consecutive patients undergoing elective coronary artery bypass grafting (CABG) using CPB were studied. They were randomly divided into three groups of 20 patients. Patients in Group A underwent bi-caval venous cannulation and received crystalloid cardioplegia. Group B patients underwent right atrial cannulation and received crystalloid cardioplegia. Group C patients underwent right atrial cannulation and received blood cardioplegia. In each case. cardioplegia was administered antegrade via the aortic root. Plasma [K+], MAP. and hemoglobin concentration (Hb) were measured over an 8-min period following cardioplegia administration (pilot studies indicated pressure changes occuring post cardioplegia administration up to this time). The combination of bi-caval cannulation and crystalloid cardioplegia (Group A) was associated with the least increase in plasma [K+] and no decrease in MAP. The maximum [K+] for this Group was 4.2 mmol/L (4.6% increase). The minimum mean pressure was 57 mmHg (13.6% increase). Both right atrial cannulation groups (B and C) showed a large rise in plasma [K+] and a decrease in MAP. Group B maximum [K+] was 5.2 mmol/L (27.5% increase). Group C was also 5.2 mmol/L (26.0% increase). Group C showed the largest pressure decrease, the minimum mean pressure was 45 mmHg (21.3% decrease). The Group B minimum mean pressure was 45 mmHg (8.7% decrease). Our results show that patients undergoing CPB operations who are deemed to be at increased risk of suffering adverse effects from hypotensive episodes may benefit from bicaval cannulation and caval snaring, in preference to right atrial cannulation. Crystalloid cardioplegia may be preferable to blood cardioplegia in these cases to maintain the MAP.