Dobutamine improves gastrointestinal mucosal blood flow in a porcine model of endotoxic shock.

OBJECTIVE: To test the hypothesis that saline solution plus dobutamine increases gastrointestinal mucosal perfusion better than saline solution alone in a model of endotoxic shock. DESIGN: Prospective, randomized, unblinded study. SETTING: Animal research laboratory affiliated with a university teaching hospital. SUBJECTS: Twelve female pigs, weighing 30 to 32 kg. INTERVENTIONS: Animals were anesthetized, and their lungs were mechanically ventilated. Catheters were inserted into the right atrium, pulmonary artery, and carotid artery for blood sampling and blood pressure and cardiac output measurements. A tonometer and a laser Doppler probe were placed in the lumen of the stomach and the ileum for determination of mucosal acid-base status and measurement of mucosal blood flow. Group 1 animals (n = 6) received an infusion (T = 0 min) of 150 mcirog/kg Escherichia coli endotoxin and normal saline solution (0.3 mL/kg/min). Group 2 animals (n = 6) received an infusion of endotoxin and were resuscitated with the same method as used in group 1, but an infusion of dobutamine (5 microg/kg/min) was begun at T = 60 mins, and continued for the duration of the experiment. MEASUREMENTS AND MAIN RESULTS: Both experimental regimens produced shock, with decreased mean arterial pressure and systemic vascular resistance, without change in cardiac output and oxygen delivery. Endotoxin plus saline infusion decreased gastrointestinal mucosal blood flow to <60% of baseline and decreased gastrointestinal pH. In contrast, gastrointestinal mucosal blood flow returned to baseline values, and intramucosal pH tended to normalize by the end of the saline solution plus dobutamine resuscitative protocol. CONCLUSION: Compared with saline solution alone, saline solution plus dobutamine increased blood flow to the gastrointestinal mucosa, and may have partially improved oxygenation.

[Anaerobic infections of the soft tissues]. / Les infections anaérobies des tissus mous.

Anaerobic soft tissue infections are still life threatening infections. Although their frequency is actually moderate; they remain severe because physicians are often insufficiently aware of them. Although the classification between myonecrosis and necrotizing fasciitis is still valid, these infections share so many points in common that they can be considered together. Their origin is often traumatic or surgical but may also be secondary to an ulcer or a small wound in a high-risk patient: arteriosclerotic, diabetic. Hypoxia, traumatic muscle crush, heavy bacterial contamination as well as incorrect antibiotic prophylaxis are the major reasons for their occurrence. Management consists of antibiotics adapted to both anaerobic and associated aerobic bacteria, large and early surgical debridement, but with conservative excision, and intensive hyperbaric oxygen therapy. Strict prevention measures must be applied to avoid their occurrence.

The contrasting effects of dobutamine and dopamine on gastric mucosal perfusion in septic patients.

To test the hypothesis whether or not dobutamine or dopamine infusion increases gastric mucosal perfusion, a prospective randomized crossover trial was conducted on 10 septic patients in the intensive care unit of a university hospital. Systemic hemodynamic, oxygen transport, and gastric perfusion assessed by gastric intramucosal pH and laser Doppler flowmetry were measured at baseline and after administration of dobutamine or dopamine (5 micrograms/kg/min). Both increased oxygen transport. In response to dobutamine, gastric mucosal blood flow increased (+32 +/- 14% from baseline; p < 0.05), gastric tonometered PCO2 and gastric arterial PCO2 difference decreased (58 +/- 7 versus 52 +/- 7 mm Hg; p < 0.05; 16.8 +/- 7.0 versus 10.5 +/- 7.2 mm Hg; p < 0.05), and intramucosal pH increased (7.23 +/- 0.05 versus 7.29 +/- 0.06; p < 0.05). In response to dopamine, gastric mucosal blood flow decreased (-28 +/- 8% from baseline; p < 0.05), gastric tonometered PCO2, gastric-arterial PCO2 difference, and calculated intramucosal pH were unchanged (58 +/- 7 versus 61 +/- 9 mm Hg, ns; 16.8 +/- 7.0 versus 18.9 +/- 8.4 mm Hg, ns; 7.24 +/- 0.05 versus 7.21 +/- 0.06, ns). We speculated that despite an oxygen transport increase, dobutamine and dopamine have affected differently gastric mucosal perfusion in septic patients.

[Carbon monoxide poisoning]. / L'intoxication au monoxyde de carbone.

Carbon monoxide (CO) poisoning still represents a frequent and severe casualty in France. Aside from the well-known effect of CO on hemoglobin, the role of CO binding to other hemoproteins like myoglobin and cytochrome a3 has been more recently recognized. Moreover, in addition to these hypoxic injuries, the reoxygenation phase may itself induce toxic effects by a mechanism close to the ischemia-reperfusion phenomenon. Clinical manifestations include neurologic disturbances, cardiac arrhythmia, respiratory and circulatory failures which usually disappear with removal from toxic atmosphere and administration of oxygen. However, long term neurologic manifestations may occur and lead to important functional impairment and disability. Hyperbaric oxygen is actually the treatment of choice to avoid the occurrence of delayed sequelae. HBO is advocated in every patient who remains comatose on hospital admission, who has lost consciousness during toxic exposure or with persisting neurologic abnormalities. CO poisoned pregnant women should also undergo HBO.

Skeletal muscle microvascular blood flow and oxygen transport in patients with severe sepsis.

To compare skeletal muscle microvascular blood flow at rest and during reactive hyperemia in septic patients, a prospective, controlled trial was conducted on 16 patients with severe sepsis and a control group of 10 patients free of infection in the intensive care unit of a university hospital. Systemic hemodynamics, whole-body oxygen transport, and skeletal muscle microvascular blood flow at rest and during reactive hyperemia were measured. Reactive hyperemia was produced by arrest of leg blood flow with a pneumatic cuff; on completion of the 3 min ischemic phase the occluding cuff was rapidly deflated to 0. Hemodynamic and oxygen-derived variables were determined invasively. Skeletal muscle microvascular blood flow data were obtained using a laser Doppler flowmetry technique and values expressed in millivolts. Whole-body oxygen delivery in septic patients was increased compared with control subjects. Resting skeletal muscle blood flow was decreased in septic patients compared with control subjects (233 +/- 52 versus 394 +/- 93 mV; p < 0.05). Peak flow during reactive hyperemia was also decreased in septic patients compared with control subjects (380 +/- 13 versus 2,033 +/- 853 mV; p < 0.05). Cyclic variation in blood flow (vasomotion) was observed in control subjects but not in septic patients. Skeletal muscle microvascular perfusion is altered in patients with severe sepsis despite normal or elevated whole-body oxygen delivery. These microvascular abnormalities may further compromise tissue nutrient flow and may contribute to the development of organ failure in septic patients.

Cervical necrotizing fasciitis: clinical manifestations and management.

Forty-five cases of cervical necrotizing fasciitis are reported, and their clinical, bacteriologic, and therapeutic implications are considered. Fasciitis was of dental origin in 78% of cases, pharyngeal in 16%, and surgical or posttraumatic in 6%. The condition extended to the face in 22% of cases, to the lower part of the neck in 56%, and to the mediastinum in 40%. Soft-tissue cultures were positive in 78% of cases. Anaerobes were isolated along with aerobes in 49% of cases (mean, 2.2 isolates per patient) and in pure culture in 22%. Treatment included surgical debridement and drainage and the administration of antibiotics active against both anaerobic and gram-negative aerobic bacteria. Hyperbaric oxygen was used for adjunctive treatment. The bacteria involved did not affect clinical manifestations, extension, or mortality. The survival rate among our patients was 78%. Mortality was significantly higher among cases with mediastinal extension (44% vs. 7%; P < .01); thus the prompt recognition and drainage of sites of mediastinal extension are of critical importance. Other risk factors for death were an age of > 70 years, underlying diabetes, the development of septic shock within 24 hours after admission, and prolonged prothrombin time.