Jean Jacques Lehot

Usefulness of procalcitonin for diagnosis of infection in cardiac surgical patients.

ObjectiveTo determine the value of procalcitonin (PCT) as a marker of postoperative infection after cardiac surgery. DesignA prospective single institution three phase study. SettingUniversity cardiac surgical intensive care unit (31 beds). PatientsPhase 1: To determine the normal perioperative kinetics of PCT, 20 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass were included. Phase 2: To determine whether PCT may be useful for diagnosis of postoperative infection, 97 consecutive patients with suspected infection were included. Phase 3: To determine the ability of PCT to differentiate patients with septic shock from those with cardiogenic shock, 26 patients with postoperative circulatory failure were compared. Measurements and Main ResultsPhase 1: Serum samples were drawn for PCT determination after induction of anesthesia (baseline), at the end of surgery, and daily until postoperative day (POD) 8. Baseline serum PCT concentration was 0.17 ± 0.08 ng/mL (mean ± sd). Serum PCT increased after cardiac surgery with a peak on POD 1 (1.08 ± 1.36). Serum PCT returned to normal range on POD 3 and remained stable thereafter. Phase 2: In patients with suspected infection, serum PCT was measured at the same time of C-reactive protein (CRP) and bacteriologic samples. Among the 97 included patients, 54 were infected with pneumonia (n = 17), bacteremia (n = 16), mediastinitis (n = 9), or septic shock (n = 12). In the 43 remaining patients, infection was excluded by microbiological examinations. In noninfected patients, serum PCT concentration was 0.41 ± 0.36 ng/mL (range, 0.08–1.67 ng/mL). Serum PCT concentration was markedly higher in patients with septic shock (96.98 ± 119.61 ng/mL). Moderate increase in serum PCT concentration occurred during pneumonia (4.85 ± 3.31 ng/mL) and bacteremia (3.57 ± 2.98 ng/mL). Serum PCT concentration remained low during mediastinitis (0.80 ± 0.58 ng/mL). Five patients with mediastinitis, two patients with bacteremia, and one patient with pneumonia had serum PCT concentrations of <1 ng/mL. These eight patients were administered antibiotics previously and serum PCT was measured during a therapeutic antibiotic window. For prediction of infection by PCT, the best cutoff value was 1 ng/mL, with sensitivity 85%, specificity 95%, positive predictive value 96%, and negative predictive value 84%. Serum CRP was high in all patients without intergroup difference. For prediction of infection by CRP, a value of 50 mg/L was sensitive (84%) but poorly specific (40%). Comparing the area under the receiver operating characteristic curves, PCT was better than CRP for diagnosis of postoperative sepsis (0.82 for PCT vs. 0.68 for CRP). Phase 3: Serum PCT concentration was significantly higher in patients with septic shock than in those with cardiogenic shock (96.98 ± 119.61 ng/mL vs. 11.30 ± 12.3 ng/mL). For discrimination between septic and cardiogenic shock, the best cutoff value was 10 ng/mL, with sensitivity of 100% and specificity of 62%. ConclusionCardiac surgery with cardiopulmonary bypass influences serum PCT concentration with a peak on POD 1. In the presence of fever, PCT is a reliable marker for diagnosis of infection after cardiac surgery, except in patients who previously received antibiotics. PCT was more relevant than CRP for diagnosis of postoperative infection. During a postoperative circulatory failure, a serum PCT concentration >10 ng/mL is highly indicative of a septic shock.

Relative importance of flow versus pressure in splanchnic perfusion during cardiopulmonary bypass in rabbits.

Background Decreased gastrointestinal perfusion has been reported during cardiopulmonary bypass (CPB). Conflicting results have been published concerning thresholds of pressure and flow to avoid splanchnic ischemia during CPB. This study compared splanchnic perfusion during independent and randomized variations of CPB pump flow or arterial pressure. Methods Ten rabbits were studied during mild hypothermic (36°C) nonpulsatile CPB using neonatal oxygenators. Simultaneous measurements of tissue blood flow in four different splanchnic areas (gastric, jejunum, ileum, and liver) were performed by laser Doppler flowmetry (LDF) before CPB (T0) and during a 4-step factorial experimental block design. Pressure and flow were alternatively high or low in random order. Results Laser Doppler flowmetry was significantly lower than pre-CPB value but was better preserved (analysis of covariance) in all organs, except liver, when CPB flow was high, whatever the pressure. Splanchnic LDF values in the low-versus high-flow groups expressed as perfusion unit were (mean ± SD): stomach, 94 ± 66 versus 137 ± 75; jejunum, 118 ± 78 versus 172 ± 75; ileum, 95 ± 72 versus 146 ± 83; and liver, 79 ± 72 versus 108 ± 118. No significant difference of LDF was observed between the high- and low-pressure groups, whatever the flow, except for liver: stomach, 115 ± 64 versus 117 ± 83; jejunum, 141 ± 80 versus 148 ± 83; ileum, 127 ± 87 versus 114 ± 76; liver, 114 ± 88 versus 73 ± 70. Conclusion Prevention of splanchnic ischemia during CPB should focus on preservation of high CPB blood flow rather than on high pressure.

The Impact of Atrio-Biventricular Pacing on Hemodynamics and Left Ventricular Dyssynchrony Compared With Atrio–Right Ventricular Pacing Alone in the Postoperative Period After Cardiac Surgery

OBJECTIVESnThe aims of this study were to test the hypotheses that in the postoperative period after coronary artery bypass graft surgery (1) atrio-right ventricular (RA-RV) pacing induces a decrease in cardiac output compared with RA pacing alone and (2) atrio-biventricular (RA-BiV) pacing improves CO compared with RA-RV pacing.nnnDESIGNnA prospective observational study.nnnSETTINGnA single-center university hospital.nnnPARTICIPANTSnPatients referred for coronary artery bypass graft surgery.nnnINTERVENTIONSnPatients were studied during atrial, RA-RV, and RA-BiV pacing. Cardiac output (echocardiography) and left ventricular dyssynchrony were assessed at each step.nnnMEASUREMENTS AND MAIN RESULTSnRA-RV pacing induced a significant decrease in cardiac output (4.3 +/- 1.0 to 3.7 +/- 0.8 L/min, p < 0.01) and a significant increase in left ventricular dyssynchrony (13 +/- 12 to 80 +/- 25 milliseconds, p < 0.01). Biventricular pacing induced a significant increase in cardiac output (3.7 +/- 0.8 to 4.5 +/- 1.0 L/min, p < 0.01) and a significant decrease in left ventricular dyssynchrony compared with right ventricular pacing (80 +/- 25 to 21 +/- 16 milliseconds, p < 0.05).nnnCONCLUSIONSnRA-BiV pacing improves cardiac output compared with RA-RV pacing in the postoperative period after coronary artery bypass graft surgery. This improvement is related to an improvement in left ventricular synchronicity.

Glucose versus lactated ringer's solution during pediatric cardiac surgery

OBJECTIVEnWhether intraoperative fluid infusion should contain glucose during pediatric cardiac surgery remains controversial. This study was performed to compare the effects of glucose and glucose-free solutions on blood glucose and blood insulin levels during total repair of congenital heart diseases.nnnDESIGNnProspective randomized and blinded study.nnnSETTINGnCardiovascular university center.nnnPARTICIPANTSnForty nondiabetic children, weight ranging from 4 to 10 kg, scheduled for cardiac surgical procedures requiring cardiopulmonary bypass (CPB) without total circulatory arrest.nnnINTERVENTIONSnGroup R (n = 20) was administered lactated Ringers solution intraoperatively, and group G (n = 20) received 5% glucose. Fluids were infused at a rate of 3 mL/kg/h in the two groups from the induction of anesthesia to the end of the surgical procedure. Blood glucose and insulin were sampled before infusion (Tzero), before CPB (T1), 10 minutes after initiation of CPB (T2), 10 minutes after initiation of rewarming (T2), and at the end of the procedures (T4). Postoperatively, blood glucose was measured at the first, 12th, and 24th hours.nnnMEASUREMENTS AND RESULTSnDuring the prabypass period, three children in group R had severe hypoglycemia (blood glucose < 40 mg/dL). After initiation of CPB, blood glucose increased in both groups, with a small difference at the end of the procedure. No infants in the two groups had blood glucose higher than 239 mg/dL.nnnCONCLUSIONSnGlucose withdrawal during pediatric cardiac surgery induces threatening hypoglycemia during the prabypass period, and moderate intraoperative glucose administration (2.5 mg/kg/min) is not responsible for major hyperglycemia.

Complications digestives sévères après chirurgie cardiaque sous circulation extracorporelle

ObjectifÉvaluer l’incidence, les modalités de survenue et l’évolution des complications digestives après chirurgie cardiaque sous circulation extracorporelle (CEC).MéthodeÉtude rétrospective sur 6281 adultes opérés sous CEC entre le 1er janvier 1994 et le 31 décembre 1997.RésultatsSoixante patients ont présenté 68 complications digestives (1 %): hémorragie digestive haute (n = 23), ischémie intestinale (n = 19), cholécystite aiguë (n = 7), pancréatite aiguë (n = 6), dilatation colique (n = 13). L’incidence de ces complications, faible après chirurgie coronaire (0,4 %) ou valvulaire (0,8 %), était élevée après transplantation cardiaque (6 %) ou chirurgie d’une dissection aortique (9 %). Comparés à une population témoins, les patients ayant présenté une complication digestive avaient un score de Parsonnet plus élevé (29 ± 15 contre 13 ± 12 points, P = 0,002), étaient plus souvent opérés en urgence (40/60, 66 % contre 1120/6221, 18 %; P = 0,01), avaient subi une CEC plus longue (114 ± 66 contre 74 ± 42 min, P = 0,01), et avaient présenté plus fréquement un bas débit cardiaque postopératoire (45/60, 75 % contre 435/6221, 7 %; P = 0,001). La mortalité globale en présence d’une complication digestive a été de 52 %. Les facteurs associés à la mortalité étaient: survenue d’un sepsis (OR=38,7), survenue d’une insuffisance rénale (OR=7,9), âge > 75 ans (OR= 3,5), ventilation mécanique > 7 jours (OR=2,7), association d’une complication neurologique (OR=3,9).ConclusionLes complications digestives après CEC surviennent chez une population à risque. Ces complications s’intègrent dans un contexte de défaillance multiviscérale à l’origine d’une mortalité élevée.AbstractPurposeTo determine the incidence, circumstances of occurrence and evolution of gastrointestinal complications after cardiac surgery with extracorporeal circulation (ECC).MethodsRetrospective chart study of gastrointestinal complications in 6,281 patients undergoing ECC between January 1994 and December 1997.ResultsSixty patients developed 68 gastrointestinal complications (1%). Complications included: upper gastrointestinal bleeding (n = 23), intestinal ischemia (n = 19), cholecystitis (n = 7), pancreatitis (n = 6), and paralytic ileus (n = 16). The incidence of these complications was low after coronary artery (0.4%) or valvular surgery (0.8%) and high after cardiac transplantation (6%) and after surgery for acute aortic dissection (9%). Compared with a control population, patients with gastrointestinal complication had a higher Parsonnet score (29 ± 15 vs 13 ± 12 points; P = 0.002), were more frequently operated upon as an emergency (40/60, 66% vs 1120/6221, 18%; P = 0.01), underwent ECC of longer duration (114 ± 66 vs 74 ± 42 min; P = 0.01), and presented more frequently with low cardiac output after surgery (45/60, 75% vs 435/6221, 7%; P = 0.001). The mortality rate after gastrointestinal complications was 52%. The major factor associated with mortality was the occurence of sepsis (OR=38.7). Other factors were: renal failure (OR=7.9), age > 75 yr (OR=3.5), mechanical ventilation for more than seven days (OR=2.7), associated cerebral damage (OR=3.9).ConclusionGastrointestinal complications after ECC occur in high risk surgical patients. These complications are frequently associated with other complications leading to a high mortality rate.

Effects of various flow types on maternal hemodynamics during fetal bypass: Is there nitric oxide release during pulsatile perfusion?

OBJECTIVEnThis study investigates the role of various flow conditions on maternal hemodynamics during fetal cardiopulmonary bypass.nnnMETHODSnNormothermic fetal bypass was conducted under pulsatile, or steady flow, for a 60-minute period. Fetal lamb preparations were randomly assigned to 1 of the 3 groups: steady flow (n=7), pulsatile flow (n=7), or pulsatile blocked flow bypass (n=7), where fetuses were perfused with Nomega-nitro-L-arginine after the first 30 minutes of pulsatile flow to assess the potential role of endothelial autacoids.nnnRESULTSnMaternal oximetry and pressures remained unchanged throughout the procedure. Under fetal pulsatile flow, maternal cardiac output increased after 20 minutes of bypass and remained significantly higher than under steady flow at minute 30 (8.8+/-0.7 L x min(-1) vs 5.9+/-0.5 L x min(-1), P=.02). Maternal cardiac output in the pulsatile group also remained higher than in both steady and pulsatile blocked flow groups, reaching respectively 8.7+/-0.9 L x min(-1) vs 5.8+/-0.4 L x min(-1) (P=.02) and 5.9+/-0.3 L min(-1) (P=.01) at minute 60. Maternal systemic vascular resistances were significantly lower under pulsatile than under steady flow after 30 minutes and until the end of bypass (respectively, 9.1+/-0.6 IU vs 12.7+/-1.1 IU, P=.02 and 8.9+/-0.5 IU vs 12.9+/-1.2 IU, P=.01). Infusion of Nomega-nitro-L-arginine was followed by an increase in systemic vascular resistances from 9.3+/-0.7 IU, similar to that of the pulsatile group, to 13.5+/-1 IU at 60 minutes, similar to that of the steady flow group.nnnCONCLUSIONSnMaternal hemodynamic changes observed under fetal pulsatile flow are counteracted after infusion of Nomega-nitro-L-arginine, suggesting nitric oxide release from the fetoplacental unit under pulsatile fetal flow conditions.

Should We Inhibit Gastric Acid Secretion Before Cardiac Surgery

Stress can decrease intragastric pH and cause erosion of gastric mucosa. Because cardiac surgery and cardiopulmonary bypass represent a major stress, the effects on intragastric pH of an H2-receptor antagonist, ranitidine, and an M1-muscarinic antagonist, pirenzepine, were evaluated. Intragastric pH was measured throughout elective cardiac surgery in 60 patients by a digital pH-meter during fentanyl-diazepam-nitrous oxide (50%) anesthesia. The gastric content was sampled at closure of the chest for bacterial count. Oral preoperative medication given randomly included (n = 20 in each group) 0.3 mg/kg diazepam 1 h before induction (group 1); diazepam plus ranitidine (150 mg) 1 h before induction (group 2); and diazepam plus pirenzepine (50 mg) on the evening before surgery and 1 h before induction of anesthesia (group 3).At induction intragastric pH was higher in group 2 (mean ± SD = 7.42 ± 1.07) than in group 1 (5.28 ± 2.14) (P < 0.01) but was not significantly different in group 3 (5.78 ± 1.89) than in group 1. In no group did intragastric pH change significantly during surgery. Gastric juice was sterile in 92% of group 1, in 25% of group 2, and in 71% of group 3 patients (P < 0.01). Postoperatively no gastrointestinal complications occurred, but there was a trend toward more patients developing nosocomial pneumonias in groups 2 and 3 (15%) than in group 1 (0%) (P = 0.06). Intraoperative intragastric pH is relatively high after diazepam premedication, thus the preoperative addition of ranitidine or pirenzepine would not be necessary and may possibly be hazardous.