Interpretation of blood pressure signal: physiological bases, clinical relevance, and objectives during shock states.

Achievement of a mean blood pressure (MBP) target is one of the hemodynamic goals to ensure an adequate blood perfusion pressure in critically ill patients. Arterial catheter allows for a continuous and precise monitoring of arterial pressure signal. In addition to giving a precise MBP monitoring, analysis of the blood pressure wave provides information that may help the clinician to interpret hemodynamic status. The interpretation of BP wave requires the understanding of simple principles. In this review, we first discuss the physiological mechanism responsible for arterial pressure generation. We then emphasize the interpretation of the static indexes and the dynamic indexes generated by heart-lung interactions derived from arterial pressure wave. Finally, we focus on MBP value as a therapeutic target in critically ill patients. We discuss the recommended target MBP value by reviewing available data from experimental and clinical studies.

Vascular hyporesponsiveness to vasopressors in septic shock: from bench to bedside.

PURPOSE: To delineate some of the characteristics of septic vascular hypotension, to assess the most commonly cited and reported underlying mechanisms of vascular hyporesponsiveness to vasoconstrictors in sepsis, and to briefly outline current therapeutic strategies and possible future approaches. METHODS: Source data were obtained from a PubMed search of the medical literature with the following MeSH terms: Muscle, smooth, vascular/physiopathology; hypotension/etiology; shock/physiopathology; vasodilation/physiology; shock/therapy; vasoconstrictor agents. RESULTS: Nitric oxide (NO) and peroxynitrite are crucial components implicated in vasoplegia and vascular hyporeactivity. Vascular ATP-sensitive and calcium-activated potassium channels are activated during shock and participate in hypotension. In addition, shock state is characterized by inappropriately low plasma glucocorticoid and vasopressin concentrations, a dysfunction and desensitization of alpha-receptors, and an inactivation of catecholamines by oxidation. Numerous other mechanisms have been individualized in animal models, the great majority of which involve NO: MEK1/2-ERK1/2 pathway, H(2)S, hyperglycemia, and cytoskeleton dysregulation associated with decreased actin expression. CONCLUSIONS: Many therapeutic approaches have proven their efficiency in animal models, especially therapies directed against one particular compound, but have otherwise failed when used in human shock. Nevertheless, high doses of catecholamines, vasopressin and terlipressin, hydrocortisone, activated protein C, and non-specific shock treatment have demonstrated a partial efficiency in reversing sepsis-induced hypotension.

[DIC and peripheral gangrene in a severe Plasmodium falciparum malaria: the coagulation-inflammation cycle with Plasmodium falciparum as a model]. / CIVD et gangrène périphérique dans un cas de paludisme sévère : le cycle coagulation-inflammation appliqué au Plasmodium falciparum.

Peripheral gangrene with disseminated intravascular coagulation (DIC) during severe Plasmodium falciparum malaria has already been described but is unfrequent. We report here the case of a 62-year-old man admitted in the intensive care unit of our hospital for severe Plasmodium falciparum malaria with disseminated intravascular coagulation (DIC) and peripheral gangrene of his toes that needed amputation. Pathophysiological mechanisms leading to DIC in malaria can be used as a model to explain the relation between coagulation and inflammation. Therapeutic targeting of coagulation, by acting on inflammation, could be useful to limit the coagulation-inflammation cycle.

Efficacy of an extracorporeal endotoxin adsorber system during hyperdynamic porcine endotoxemia.

BACKGROUND: Endotoxemia is a crucial factor in the pathogenesis of sepsis. Elimination of endotoxin is aimed at the reduction of sepsis-related morbidity and lethality. The objective of this study was to examine the impact of an endotoxin adsorber on hemodynamics, O(2) exchange and metabolism during resuscitated porcine endotoxemia. METHODS: Twenty pigs were randomized into 2 intervention groups (n = 7 each) and 1 control group (n = 6). Endotoxemia was induced by continuous intravenous application of lipopolysaccharide for 8 h. Adsorber therapy was started at the same time as the induction of endotoxemia or 2 h later. An extracorporeal hemoperfusion device using immobilized human serum albumin for endotoxin adsorption was used. RESULTS: Hemodynamic, metabolic and acid-base parameters, as well as the kinetics of interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor-alpha, were characteristic for endotoxic shock. Endotoxin plasma levels were low (arterial, hepatic and portal vein). None of the parameters were significantly influenced by the adsorber system. CONCLUSION: Despite typical clinical signs of endotoxemia, the adsorber system had no significant effect on hemodynamic, metabolic and acid-base parameters during endotoxic shock. The reasons for the absence of an effect are elusive; however, failure of the method per se or exceeded capacity of the adsorber cannot be excluded.

Gas embolism: an exceptional complication of radial arterial catheterization.

BACKGROUND: We report a rare complication of radial arterial catheterization in a 74-year-old man who had undergone retroperitoneal surgery for an infra-renal aortic aneurysm. A right subclavian venous catheter and a right radial artery catheter were inserted for hemodynamic monitoring. RESULTS: The patient suddenly went into a coma, with dyspnea and bradycardia, 1 day postsurgery, as a result of a cerebral gas embolism produced by the accidental entry of pressurized air into the artery via the arterial catheter. Cerebral Magnetic Resonance Imaging revealed multiple, diffuse brain lesions. Six months later the patient still had a left hemiparesis and a cognitive deficit. He walks with assistance. CONCLUSION: Misuse of an arterial catheter can lead to a severe gas embolism. The infusion system used to flush arterial catheters should be checked regularly to ensure it contains no gas.

Transient ST segment elevation in right precordial leads induced by psychotropic drugs: relationship to the Brugada syndrome.

Psychotropic Drugs and ST Segment Elevation. Transient ST segment elevation in right precordial leads with use of psychotropic drugs is reported in two cases of overdose and one case of therapeutic administration. Flecainide did not reproduce ST segment elevation. The relationship of these abnormalities to the Brugada syndrome and the electrophysiologic hypothesis are discussed.

Assessment of hemodynamic and gastric mucosal acidosis with modified fluid versus 6% hydroxyethyl starch: a prospective, randomized study.

OBJECTIVE: To investigate the effect of 4 % succinylated modified fluid gelatin (MFG) versus mean weight, highly substituted 6% hydroxyethyl starch (HES) on hemodynamic and gastric mucosal acidosis variables, in septic hypovolemic patients. DESIGN: Prospective, randomized, clinical investigation. SETTING: University hospital intensive care unit. PATIENTS: Thirty-four septic hypovolemic ventilated and hemodynamically controlled patients. INTERVENTIONS: Invasive hemodynamic and gastric tonometric measurements. MEASUREMENTS AND RESULTS: Hemodynamic and tonometric parameters were recorded at baseline and 60 min after infusion of 500 ml of each colloid. In all patients central venous pressure, pulmonary artery occlusion pressure, cardiac index and mean arterial pressure increased significantly with both colloids, and hemoglobin concentration decreased by the same amount while oxygen delivery remained stable. Gastric intramucosal pH increased from 7.27 +/- 0.08 to 7.31 +/- 0.07 (p < 0.001) with MFG and decreased non-significantly from 7.26 +/- 0.11 to 7.22 +/- 0.08 (ns) with HES. Carbon dioxide gastric mucosal arterial gradient decreased from 18 +/- 9 to 13 +/- 9 mmHg (p < 0.0005) in the MFG group and rose non-significantly from 18 +/- 11 to 21 +/- 11 mmHg with HES. CONCLUSIONS: Although MFG and 6% HES have the same hemodynamic effects, their physicochemical properties induce different responses on gastric mucosal acidosis in septic, hypovolemic and ventilated patients. These effects of MFG and HES on gastric mucosa need to be considered in patient management.

Nosocomial endocarditis in the intensive care unit: an analysis of 22 cases.

OBJECTIVES: To review the intensive care unit experience of patients with admitted or acquired nosocomial endocarditis (NE) defined according to the Duke criteria. DESIGN: Prospective, cohort study. SETTING: University teaching hospital. PATIENTS: We reviewed the records of 22 patients documented with NE during a 6-yr period from 1992 to 1997. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-two patients (9 women/13 men) aged 38-83 yrs (mean 65+/-9 yrs) had a NE (prevalence of 5 per 1,000 admissions). For six patients, NE was the reason for the admission to the intensive care unit. For 17 patients, the time elapsed between admission and diagnosis of NE was 39+/-25 days. Sixteen patients were predisposed to infection and seven had underlying heart conditions that put them at risk for acute endocarditis: three prosthetic valves, two valvular diseases, and two cardiac pacemakers. In 21 cases (one unknown portal of entry), NE was the consequence of bacteremia related to a medical or surgical procedure: 11 intravascular devices, eight surgical wounds, one tracheal procedure, and one leg ulceration. The bacteriologic agents detected in blood cultures were: staphylococci (n = 17), Streptococcus (n = 2), Pseudomonas aeruginosa (n = 2), and Candida (n = 2). Fourteen patients underwent echocardiography according to cardiac signs (cardiac failure, new cardiac murmur, or embolic event). For the eight remainders, echocardiography was performed systematically because of fever and positive blood cultures. The lesions detected by 21 transthoracic and 17 transesophageal echocardiographs were the following: vegetations (n = 19), myocardial abscesses (n = 5), and valvular perforation (n = 1). On 16 surgical indications, only five patients underwent surgery because the others were in too poor of a condition. The overall mortality was 68% (n = 15) and was directly associated with NE in 36% of cases (n = 8). Seven patients (28%) were discharged 34 days after the diagnosis of endocarditis. CONCLUSIONS: NE is a frequent nosocomial infection that occurs late during hospitalization. Persistent fever with positive blood cultures is sufficient symptomology to promptly perform an echocardiogram. The poor prognosis is related to the poor condition of those patients who cannot be referred for surgical treatment.

[Evaluation of intravenous immunotherapy with purified F(ab')2 fragments (Viperfav)]. / Evaluation de l'immunothérapie antivipérine par fragments F(ab')2 purifiés (Viperfav) par voie veineuse.

OBJECTIVES: To assess early clinical and biological prognosis factors in viper envenomings, and assess efficacy of Viperfav immunotherapy. Viperfav contains purified F(ab')2 fragments of equine antibodies. PATIENTS AND METHODS: A retrospective case review study of viper envenomings collected by two poison centers in France, treated or not treated by Viperfav, was conducted. Two hundred seven cases of viper bites including 119 moderate or severe envenomings (Grade II and III, recorded in adults and children and collected from 1992 to 1997 were included. Before treatment, clinical gradation and early biological severity criteria were collected. After treatment, or grade II and III envenomings, the two treatment groups were compared concerning severity and frequency of complications and sequelae, duration of hospitalization in intensive care unit (ICU) and duration of total hospital stay. RESULTS: Before treatment, both groups were not significantly different. In the Viperfav treatment group, there was a significantly lower incidence of complications (4% vs. 21%, p = 0.02) and sequelae (0% vs 14%, p = 0.006). ICU stay greater than 3 days occurred in 28% of patients in the symptomatic treatment group and no case was recorded in the Viperfav group (p = 0.0002). Total hospital stay was reduced significantly in the Viperfav group versus symptomatic treatment group (3.3 vs. 8.7 days, p = 0.000002). CONCLUSIONS: Viperfav immunotherapy was safe and effective for rapidly counteracting venom toxicity and improved markedly the prognosis of viper envenomations. The studied clinical and biological prognosis factors are valuable tools for predicting moderate or severe envenomings and are helpful for early prescription of Viperfav antivenom.

[Results of radiofrequency ablation of the atrioventricular junction in patients with refractory atrial arrhythmia and severe impairment of the left ventricular systolic function]. / Résultats de l'ablation de la jonction auriculoventriculaire par radiofréquence chez des patients en arythmie auriculaire réfractaire présentant une altération sévère de la fonction systolique ventriculaire gauche.

Results of radiofrequency ablation of the atrioventricular junction on functional capacity and left ventricular systolic function were assessed in 8 patients (aged 68 +/- 12 years) with refractory atrial fibrillation and severe left ventricular dysfunction, the mean ejection fraction being 31 +/- 11% (range: 20-48%). A clinical, echocardiographic and angioscintigraphic follow-up was performed 24 hours (basal), 3 and 6 months after the procedure. During follow-up, all patients reported the disappearance of palpitations and tiredness, a significant and early regression of effort dyspnoea from average NYHA Class 3.4 +/- 0.7 to 2.2 +/- 0.4 (M3), (p < 0.01), a decrease in end diastolic echocardiographic dimensions (from 57 +/- 10 to 52 +/- 9 mm (M3); p < 0.05) resulting in an increase in fractional shortening from 26 +/- 7% to 34 +/- 6%; p < 0.05. The isotopic EF increased from 31 +/- 11% to 42 +/- 12% (M3) (p < 0.01), and attained 48 +/- 12% (M6). This study shows that controlling the frequency and regularity of cardiac rhythm by ablation of the atrioventricular junction in patients with refractory AF and left ventricular dysfunction results in functional and haemodynamic improvement, especially when there is no apparent underlying cardiac disease. This suggests that this method should be proposed in all patients with refractory atrial fibrillation and left ventricular dysfunction.

[Detection of left cardiopathy using echocardiography during acute respiratory failure in chronic respiratory insufficiency]. / Dépistage des cardiopathies gauches par échocardiographie au cours de l'insuffisance respiratoire aiguë des insuffisances respiratoires chroniques.

Echocardiography was performed in a systematic fashion in 58 patients suffering from on-chronic respiratory failure (IRC) who were admitted to the intensive care unit. The prevalence of left ventricular disease in patients with IRC who were admitted to the intensive care unit was 31%, there were 18 cases of cardiac disease: nine had hypertrophic cardiac disease (two with intraventricular gradients), three had dilated cardiomyopathies, and there were six cases of ischaemic cardiac disease. Among these cases, six had not previously been diagnosed as having cardiac disease (10%). In cases with poor echogenicity by the transthoracic root, oesophageal echocardiography was performed and this improved the feasibility of a good examination with only a five per cent failure rate. Left ventricular disease was implicated in the clinical assessment eleven times (19%), either on admission (nine times) or during the course of the in-patient treatment (twice). In directing the initial assessment and the aetiological treatment, echocardiography directly contributed to better management in six cases (10%). As regards the number of cases of cardiac disease which were detected, the study confirms the value of this technique at the bedside of the patient. The use of the transoesophageal route improves the diagnostic value including those patients who were intubated and ventilated.

[Recanalization of chronic occlusions and myocardial infarction occurring during reocclusion. Apropos of 2 cases]. / Désobstruction des occlusions chroniques et survenue d'un infarctus lors de la réocclusion. A propos de deux observations.

Although recent techniques have significantly improved the frequency of disobliteration of chronic occlusions, the potential complications in terms of mortality, emergency bypass surgery and myocardial infarction seem as common as in angioplasty of stenosis. Of these complications, the occurrence of infarction during reocclusion at the site of angioplasty has not been described and even been refuted by some authors. We report two cases of acute infarction, one of which was transmural, occurring during late reocclusion after disobliteration of a chronically occluded artery.