Marc Reynaert

Effect of Phosphate On Oxygen-hemoglobin Affinity, Diphosphoglycerate and Blood-gases During Recovery From Diabetic-ketoacidosis

The effects of intravenous phosphate administration on the hemoglobin-oxygen affinity, the 2,3 diphosphoglycerate level and blood gases were investigated in twenty severe diabetic patients with ketoacidosis in the intensive care unit. Ten received phosphate (mean total amount for each patient = 300 mEq) and the others did not. The only significant difference noted in all indices measured during the recovery period of eight days was seen to occur after 48 h; the P50 in vivo (Torr) was slightly higher in the group who received phosphate (22.5±1.6 vs 20.5±2.2) and for the Hill coefficient (2.4±0.2 vs 2.2±0.1). This drop in the oxygen affinity of hemoglobin may be useful in subjects at risk of hypoxia, for example those with cardiac or respiratory failure and justifies the use of phosphate in the first 48 h of treatment of patients with diabetic ketoacidosis.

PaCO2/ETCO2 gradient: early indicator of thrombolysis efficacy in a massive pulmonary embolism

End tidal CO2 measurement may be helpful in detecting the efficacy of thrombolysis after a massive pulmonary embolism. We report the case of a 76-year-old man with a massive pulmonary embolism, who required early intubation and mechanical ventilation. Thrombolysis with rtpA (total dosage: 60 mg) was initiated. During this procedure, clinical data, arterial blood gases and end-tidal CO, with a capnograph were recorded. Before thrombolysis the P(a-ET)CO2 gradient was raised to 25 mmHg. During thrombolysis, the clinical data improved and the P(a-ET) gradient fell to 14 mmHg. We postulate that the P(a-ET)CO2 gradient seems to be a reasonable indicator of efficacy of thrombolysis in this setting. However. the gradient did not return to normal values(45 mmHg). The possible reasons for this may be that during mechanical ventilation there was a large ventilation- perfusion ratio and the cardiac output may have still reduced. With these limitations, we conclude that the P(a-ET)CO2 gradient should be evaluated as an indicator of pulmonary reperfusion in massive pulmonary embolism

The Importance of the Balloon Reservoir Volume of a Cpap System in Reducing the Work of Breathing

We have previously reported, that the work of breathing in spontaneously breathing patients on CPAP could be significantly reduced by increasing the volume of the balloon reservoir in the circuit of a CPAP system from 3 to 23 l. We now report a study designed to determine the optimum balloon reservoir volume for the minimization of the work of breathing. Twenty intubated, spontaneously breathing patients were connected to a CPAP system with interchangeable balloon reservoirs. In each patient the work of breathing was measured for reservoir volumes of 3, 6, 12, 18, and 24 l attached in random order, while the positive airway pressure was held constant at 10 cm H2O. The balloons were constructed of the same material and had similar compliance. Rebreathing was prevented with use of one-way valves. Significant (p<0.001) decreases in the work of breathing were found on increasing reservoir volumes from 3 to 6, 6 to 12, and 12 to 18 l. A less significant (p<0.01) decrease in the work of breathing was found between reservoirs of 18 and 24 l. Rebreathing did not occur with significantly (p<0.001) lower flow rates when large reservoirs were used. We conclude that a balloon reservoir of 18 l represents the best compromise between reduction in the work of breathing, utilization of low source flow, and convenience of clinical use.

Volumetric capnography: reliability and reproducibility in spontaneously breathing patients

Volumetric capnography provides a breath‐by‐breath analysis of ventilation‐perfusion imbalances and deadspace volumes. The technique has been best described in intubated and ventilated patients, but promising clinical applications also concern spontaneously breathing patients. The objective of the study was to verify the reliability and reproducibility of a new capnographic program in various types of clinical conditions. In a first step, 56 patients, either healthy or with acute respiratory disorders, were connected to a sidestream gas sampler and flow sensor through a mouthpiece. An acquisition software synchronized expired CO2 and flow data to create volumetric capnographic curves. Mixed expired CO2 partial pressure, corresponding to the exhaled CO2 of the effective tidal volume, was simultaneously collected in a neoprene bag for comparison. In a second step, changes in airway deadspace before and after the adjunction of known spacer volumes were compared in six healthy volunteers. The mean difference between both methods in measuring mixed expired CO2 partial pressure was −0·9u2003mmHg (SE 0·2u2003mmHg, P<0·001). The limits of agreement extended from −4·4 to 2·5u2003mmHg. The interobserver correlation coefficient for reproducibility was 0·98. Airway deadspace volume, after correction for extra volumes, was not statistically different than the basic value (Pu2003= 0·89). In conclusion, volumetric capnography can be compared with references when used in spontaneously breathing patients. Future developments and clinical applications should clarify its role as a non‐invasive method for deadspace and ventilation‐perfusion imbalances analysis.

The importance of the circuit capacity in the administration of CPAP.

The effectiveness of Continuous positive airway pressure (CPAP) administration in improving blood oxygenation and the importance of the circuit capacity, by checking two different volumes of balloon reservoirs (a 3 1 versus 23 1 balloon), in reducing the work of breathing is presented. Twenty-five postoperative patients, after major gastrointestinal interventions were included in this study. Each patient being studied under three different conditions: Phase I: spontaneous breathing, Phase II: CPAP — 11 cmH2O, 3 1 balloon reservoir; Phase III: CPAP — 11 cmH2O, 23 1 balloon reservoir. All patients were intubated and were breathing room air. The results obtained clearly show a significant improvement in blood oxygenation due to CPAP, pM0.001. In addition, the work of breathing was considerably reduced utilizing a large capacity system with significant lower flow rates, pM0.001 and p(0.0001 respectively. Furthermore, rebreathing was prevented by maintaining continuous bubbling in the exit chamber and proved by having no change in PaCO2.

Défaillance multiviscérale précoce associée à la pancréatite aiguë : stratégie thérapeutique chirurgicale ou conservatrice ?

Resume La pancreatite aigue severe est grevee d’une mortalite avoisinant 10xa0a 20xa0%. La cause principale de mortalite est de nos jours l’infection des tissus (peri) pancreatiques necroses. Neanmoins, la defaillance multiviscerale precoce, apparaissant durant la premiere semaine d’evolution, reste une source considerable de morbidite et est encore a l’origine de 20xa0a 50xa0% des deces malgre les progres de la reanimation. Actualites et points forts. – L’activation prematuree des pro-enzymes digestives, une atteinte precoce de la microcirculation pancreatique, et la stimulation excessive des cellules immunitaires effectrices sont les trois mecanismes physiopathologiques interactifs de la necrose glandulaire. Ces dernieres annees, le syndrome de reponse inflammatoire systemique et le cortege de mediateurs actives en cascade sont apparus comme l’element cle determinant les lesions tissulaires a distance de la glande. Dans 80xa0% des cas la defaillance multiviscerale precoce est associee a une necrose sterile mais le parallelisme anatomoclinique et physiopathologique n’est pas absolu. En l’absence d’etude controlee, il n’existe aucun argument physiopathologique, clinique ou economique pouvant justifier la resection des tissus necroses steriles dans le but de prevenir ou de controler les defaillances viscerales. Ainsi, des modalites therapeutiques non chirurgicales et non specifiques a la pancreatite aigue ont ete etudiees pour limiter la defaillance multiviscerale, prevenir l’infection pancreatique, diminuer le recours a la chirurgie et ameliorer la survie de ces patients. Les moyens therapeutiques incluent la sphincterotomie endoscopique en urgence dans la pancreatite biliaire, l’antibioprophylaxie de l’infection de la necrose, et la nutrition intrajejunale precoce. La ponction iterative de la necrose doit etre integree dans toute strategie therapeutique conservatrice afin de depister precocement l’infection pancreatique qui reste une indication absolue de drainage qu’il soit chirurgical ou autre. Perspectives. – De nombreux arguments experimentaux et physiopathologiques plaident en faveur du developpement d’un traitement immunomodulateur dans la pancreatite aigue severe. L’administration precoce d’une ou de plusieurs molecules antagonistes des mediateurs inflammatoires associees eventuellement a un inhibiteur des proteases pourrait influencer favorablement les deuxxa0determinants pronostiques majeurs. Les deuxxa0elements sont l’intensite de la defaillance multiviscerale et le volume de la necrose (peri) glandulaire qui conditionne la survenue de l’infection pancreatique. Les benefices d’un traitement immunomodulateur restent cependant a demontrer sur le plan clinique.

Comment on the paper “The importance of the circuit capacity in the administration of CPAP”

The difference between the slope in the straight portion of the V/P curve and the TSLC was lower in group A 14.0 + 9.7 (data from the 7 pts presenting an inflection point) and in group B 15.0_+ 7 than in group C 21.96 _+ 8.4. Noting that 4 patients in group A did not present any inflection point and that the remaining 7 presented a lower slope TSLC it seems possible to suggest that patients in group A (undergoing LFPPV-ECCO2R ) presented not only a lower TSLC but also a straighter curve. Further studies are required in a larger number of patients to clarify this point. The number of patients appears too low to draw any conclusion about differences in terms of V/P curves, among survivors and non-survivors, in patients treated with LFPPV-ECCO2R. However, of 4 patients who did not present an inflection point in group A, 2 survived and 2 did not survive. The slope in the straight part of the V/P curve was slightly higher in survivors (38 _+ 13 ml cm H20-I) than in non-survivors (31 _+12 ml cm H2 Oi ) as was TSLC (28_+4; 25_+9), but in both cases the difference was not statistically significant.