Administration périopératoire de bêtabloquants : enquête de pratique

OBJECTIVES

To evaluate the anaesthesiologists' attitude concerning the perioperative administration of betablockers (BB), especially prophylactic BB, in order to prevent postoperative cardiac complications.

METHODS

A questionnaire including 20 items was sent to 700 anaesthesiologists of 4 French departments (Ain, Isere, Loire et Rhone).

RESULTS

The response rate was 30%. Eighty-eight percent of respondents prescribed the BB with the premedication, on the day of the surgery in patients who were on regular BB. Before major surgery, 37% percent of respondents always or usually introduced prophylactic BB in patients with high cardiac risk. Atenolol was the drug of choice for 68% of perioperative BB users. Seventy-one percent of anaesthesiologists using prophylactic BB asked for a cardiologic opinion before starting BB therapy.

CONCLUSION

In practice, anaesthesiologists continued BB during the perioperative period in patients who were on chronic treatment with BB. However, prophylactic perioperative administration of BB in patients with high cardiac risk is still inadequate and dependent on a cardiologic opinion.

[New aspects and perspectives on cardiac arrest]

OBJECTIVES

To analyse the current knowledge based on the experimental and the clinical research studies focused on the main fields of cardiopulmonary resuscitation.

DATA SOURCES

International guidelines and recent review articles. Data collected from the Medline database with the key word: cardiac arrest.

STUDY SELECTION

Research studies published during the last ten years were reviewed. Relevant clinical information was extracted and discussed when it induced changes in guidelines.

DATA SYNTHESIS

Promising improvements on basic and advanced life supports are proposed. Chest compressions prevail over ventilation. Alternatives to classical chest compressions are tested. Ventilatory volume must be reduced from 1000 to approximatively 500 mL for each breath with oxygen. Biphasic waveform defibrillators and automated external defibrillators will be considered as the best devices in the near future. Some non-catecholaminergic vasopressors could reduce the use of epinephrine for advanced cardiac life support. Lidocaine could be replaced by amiodarone as anti-arrhythmic drug of choice. New post-resuscitation therapeutic strategies are evaluated, especially coronary reperfusion when the cause of cardiac arrest is cardiac.

CONCLUSION

Many fields of cardiopulmonary resuscitation are investigated. Some relevant informations are included in the last international guidelines published in 2000, but most of them need complementary studies before other changes could be recommended for routine practice.

[Perioperative medical complications in orthognathic surgery]

PURPOSE

To describe per and postoperative medical complications.

STUDY DESIGN

Prospective, observational study.

PATIENTS

Between July and December 1999, 59 patients scheduled for programmed orthognathic surgery were included.

METHODS

Anaesthetic and surgical procedures were standardised including patient information and training of surgical ward' nurses. During perioperative periods (in operative and recovery theater and in surgical ward), all the events were qualified on an anaesthetic spreadsheet for a qualitative analysis (description of events and treatment procedures).

RESULTS

Two main complications were described 1) one atelectasia due to blood inhalation during the recovery period and 2) local sepsis in surgical ward. These two events were medically treated and recovered. No need of blood transfusion or stay in ICU were noted.

CONCLUSION

Anaesthetic and surgical cooperation is associated with poor morbidity of this functional surgery performed in young subjects.

Severe heart failure secondary to 5-fluorouracil and low-doses of folinic acid: usefulness of an intra-aortic balloon pump

OBJECTIVES

To report 5-fluorouracil in combination with folinic acid as a cause of severe nonischemic heart failure and to demonstrate the potential usefulness of an intra-aortic balloon pump.

DESIGN

Case report.

SETTING

An adult, 19-bed medical/surgical intensive care unit of a university hospital.

PATIENTS

A patient, who developed severe heart failure secondary to 5-fluorouracil infusion with low-dose folinic acid, which was introduced to treat a rectal cancer, was transferred from a cancer institute to our intensive care unit 4 days after the treatment was initiated.

INTERVENTIONS

Electrocardiography, determination of level of cardiac enzymes, echocardiography, radial arterial catheterization, mechanical ventilatory support, continuous venovenous hemodialysis, vasopressors, and secondary intra-aortic balloon pump.

MEASUREMENT AND MAIN RESULTS

During shock, the patient's systolic blood pressure progressively decreased to 70 mm Hg, despite inotropic agents and vasopressors. Transesophageal echocardiography showed a calculated left ventricular ejection fraction within 20% with global hypokinesia. Electrocardiography showed sinus tachycardia with only nonspecific ST-T changes. Results of serial determination of levels of cardiac enzymes were not significant for myocardial infarction. Treatment with an intraaortic balloon pump was initiated and resulted in a dramatical improvement within 48 hrs. The patient was gradually weaned from vasopressors and the intra-aortic balloon pump. By the tenth day, echocardiography showed a septoapical hypokinesia with a 50% left ventricular ejection fraction. On the 30th day, the echocardiography was considered normal.

CONCLUSION

Intravenous 5-fluorouracil in combination with low doses of folinic acid can induce severe nonischemic heart failure. In such a case, an intra-aortic balloon pump could be useful by providing left ventricular function support when inotropic agents and vasopressors fail to restore normal hemodynamics.

Non-invasive aortic blood flow measurement

Invasive monitoring is rarely used for children undergoing routine anaesthesia, whereas usual non-invasive haemodynamic measurements such as heart rate and blood pressure monitoring are unable to detect cardiovascular changes rapidly and precisely. In contrast, oesophageal aortic blood flow echo-Doppler is an easy, non-invasive and accurate method to monitor cardiac performance properly and continuously. Therefore, it could represent a useful addition to peri-anaesthetic monitoring techniques, particularly in infants and small children.

Time course of oxidative stress after major burns

OBJECTIVE

To evaluate oxidative stress resulting from major burns in humans.

DESIGN

Prospective clinical study with control group.

SETTING

Mechanically ventilated adult patients admitted with more than 30% total burn surface area.

PATIENTS AND PARTICIPANTS

20 patients with a mean body surface burned area of 54%.

MEASUREMENTS AND RESULTS

The oxidative stress evaluation was based on measurements of trace elements, vitamins, antioxidant enzymatic activity and end-products of lipid peroxidation. During the first 5 days after injury burn patients exhibit a decrease in selenium and antioxidant vitamins (C, beta-carotene, lycopene) and an increase in lipid peroxidation products (TBARS).

CONCLUSION

Our results suggest that major burn is associated with oxidative stress during the 5 days after the initial injury, as demonstrated by a simultaneous decrease in antioxidant vitamins and a large increase in TBARS.

Widely meshed autograft associated with cultured autologous epithelium for the treatment of major burns in children: report of 12 cases

This is a retrospective study of the combination of widely meshed autograft and autologous cultured keratinocytes. We used this method faced with the lack of allogenic skin, as an alternate to the Cuono method. Twelve children suffering extensive burn injury (deep burns of 60%+/-16 of the total body surface) underwent this grafting procedure. The surgical treatment consisted of an early surgical excision, with an immediate coverage by autografts as much as possible. When cultured epithelium was available, a large mesh autograft was applied and covered with cultured epidermis sheets during the same operative procedure. The rate of take was of 84% (+/- 12). No secondary graft loss was observed. This means of coverage appeared reliable and resistant. On average, this method allowed the epidermization of 30% (+/-9) of the total body surface of the children. The average hospital stay of the children was 64+/-20 days. All the children recovered to lead a normal life. The school delay after rehabilitation is one year. This technique is an alternative to Cuono's method when allografts are missing. The combination of autograft and autologous cultured epidermis sheets appeared more effective than one of these techniques applied alone, as if the suggested coupling induced a synergy.

Interaction of halogenated anesthetics with dobutamine in rat myocardium

BACKGROUND

Halogenated anesthetics potentiate the positive inotropic effects of alpha- and beta-adrenoceptor stimulations, but their interactions with dobutamine remain unknown.

METHODS

The effects of halothane, isoflurane, sevoflurane, and desflurane (1 and 2 minimum alveolar concentration) on the inotropic responses induced by dobutamine (10(-8)-10(-4) M) were studied in rat left ventricular papillary muscles in vitro. Inotropic effects were studied under low (isotony) and high (isometry) loads. The authors also studied the lusitropic effects in isotonic (R1) and isometric (R2) conditions. Data are the mean percentage of baseline +/- SD.

RESULTS

Dobutamine induced a positive inotropic effect (active isometric force: 185+/-36%, P < 0.001) and a positive lusitropic effect under low load (R1: 78+/-9%, P < 0.001), but not under high load (R2: 95+/-21%, not significant). Halothane, isoflurane, and sevoflurane did not modify the positive inotropic effect of dobutamine. Even in the presence of alpha-adrenoceptor blockade, isoflurane did not potentiate the positive inotropic effect of dobutamine. Desflurane significantly enhanced the positive inotropic effect of dobutamine (active isometric force: 239+/-35%, P < 0.001), but this potentiation was abolished by pretreatment with reserpine. In contrast to halothane, isoflurane, sevoflurane, and desflurane did not significantly modify the lusitropic effects of dobutamine.

CONCLUSIONS

Halogenated anesthetics, except desflurane, did not modify the positive inotropic effects of dobutamine. Desflurane enhanced the positive inotropic effect of dobutamine, but this effect was related to the desflurane-induced release in intramyocardial catecholamine stores.

Peritonectomy combined with intraperitoneal chemohyperthermia in abdominal cancer with peritoneal carcinomatosis: phase I-II study

OBJECTIVE

To evaluate the feasibility and the tolerance of Peritonectomy Procedure (PP) combined with Intraperitoneal Chemohyperthermia (IPCH) in patients with peritoneal carcinomatosis, a phase I-II study has been realised from January 1997 to September 1998.

METHODS

Eighteen patients were included for peritoneal carcinomatosis from colorectal cancer (13), ovarian cancer (2), gallbladder cancer (1), gastric cancer (1) and peritoneal mesothelioma (1). Peritoneal carcinomatosis were mainly advanced disease (16 stage 3 and 4, 2 stage 2). All the patients underwent surgical resection of their primary tumor with PP as described by Sugarbaker and IPCH (with Mitomycin C, Cisplatinum or both). IPCH used in this study was a "closed sterile circuit" device with inflow temperatures ranging from 46 to 48 degrees C. IPCH was performed on the same day as PP (8118) or delayed (10/18).

RESULTS

Significant down-staging of peritoneal carcinomatosis was achieved for 16 patients. One patient died postoperatively, while the morbidity rate was 6/18 (long postoperative ileus, grade 3 leucopenia and anastomotic leakage).

CONCLUSIONS

Combination of PP and IPCH could achieve significant tumoral volume reduction in peritoneal carcinomatosis. This aggressive treatment must be employed selectively because of its morbidity. Larger phase III studies are now needed.

[Severe head injuries: effects of pre-hospital mechanical ventilation on capnia]

OBJECTIVE

To assess the effect on PaCO2 of mechanical ventilation during prehospital management of severely head-injured patients.

STUDY DESIGN

Retrospective observational study.

PATIENTS

Severely head-injured patients with Glasgow coma score < or = 8. All patients were sedated, with the trachea intubated and the lungs mechanically ventilated.

METHODS

According to the capnia measured at the admission in the neurosurgical intensive therapy unit they were allocated into one of the following three groups: hypocapnia group (PaCO2 < 30 mmHg), recommended capnia group (PaCO2 = 30-38 mmHg) and hypercapnia group (PaCO2 > 38 mmHg).

RESULTS

Out of the 42 patients with similarly severe head injuries, 19% were included in the recommended capnia group (PaCO2: 34 +/- 2 mmHg), 38% in the hypocapnia group (PaCO2: 23 +/- 3 mmHg) and 43% in the hypercapnia group (PaCO2: 47 +/- 7 mmHg). In all except three, PaO2 was above 95 mmHg. The settings of ventilatory parameters on the ventilators were similar.

CONCLUSION

In 81% of patients, mechanical ventilation was inadequate as far as PaCO2 levels are concerned. Major hypocapnia and hypercapnia carry a potential risk for cerebral ischaemic. Therefore it is recommended to monitor PETCO2 during prehospital transport in medical ambulances and to determine arterial blood gases at arrival of severely head-injured patients in the admission unit for emergencies.

Comparison of the myocardial effects of desflurane and isoflurane in healthy patients: assessment by continuous oesophageal aortic blood flow echo-Doppler

Experimentally, desflurane causes a moderate positive inotropic effect and a transient increase in arterial pressure with rapid increases in concentration compared with isoflurane. We used a continuous oesophageal aortic blood flow echo Doppler device to study the myocardial effects of equi-anaesthetic concentrations of isoflurane and desflurane in 32 healthy patients undergoing superficial surgery. After induction of anaesthesia with midazolam, etomidate and fentanyl general anaesthesia was maintained in 16 patients with 0.6% end-expired concentration of isoflurane and in 16 patients with 3% end expired concentration of desflurane. Isoflurane induced a rapid decrease in aortic blood flow (ABF) which remained almost stable whereas desflurane induced an early, moderate and transient increase in ABF (1 min after introduction of the halogenated agent, mean ABF was 107 (SD 3)% in the desflurane group vs 95 (9)% in isoflurane group compared with control values before introduction of the inhalation agent; P = 0.005), followed by a marked secondary decrease in ABF. The maximal decrease in ABF reached 71 (15)% of its initial value in the desflurane group compared with 80 (14)% in the isoflurane group (ns). Neither agent caused significant changes in other variables except for PE'CO2 which decreased in both groups. Continuous ABF echo-Doppler monitoring demonstrated an early transient positive inotropic effect of desflurane.

A comparison of repeated high doses and repeated standard doses of epinephrine for cardiac arrest outside the hospital. European Epinephrine Study Group

BACKGROUND

Clinical trials have not shown a benefit of high doses of epinephrine in the management of cardiac arrest. We conducted a prospective, multicenter, randomized study comparing repeated high doses of epinephrine with repeated standard doses in cases of out-of-hospital cardiac arrest.

METHODS

Adult patients who had cardiac arrest outside the hospital were enrolled if the cardiac rhythm continued to be ventricular fibrillation despite the administration of external electrical shocks, or if they had asystole or pulseless electrical activity at the time epinephrine was administered. We randomly assigned 3327 patients to receive up to 15 high doses (5 mg each) or standard doses (1 mg each) of epinephrine according to the current protocol for advanced cardiac life support.

RESULTS

In the high-dose group, 40.4 percent of 1677 patients had a return of spontaneous circulation, as compared with 36.4 percent of 1650 patients in the standard-dose group (P=0.02); 26.5 percent of the patients in the high-dose group and 23.6 percent of those in the standard-dose group survived to be admitted to the hospital (P=0.05); 2.3 percent of the patients in the high-dose group and 2.8 percent in the standard-dose group survived to be discharged from the hospital (P=0.34). There was no significant difference in neurologic status according to treatment among those discharged. High-dose epinephrine improved the rate of successful resuscitation in patients with asystole, but not in those with ventricular fibrillation.

CONCLUSIONS

In our study, long-term survival after cardiac arrest outside the hospital was no better with repeated high doses of epinephrine than with repeated standard doses.

Myocardial effects of desflurane in hamsters with hypertrophic cardiomyopathy

BACKGROUND

The effects of desflurane on myocardial contraction and relaxation in diseased myocardium have not been completely understood.

METHODS

The effects of desflurane (1.8 to 9.4 vol%) in left ventricular papillary muscles of healthy hamsters and those with genetically induced cardiomyopathy (strain BIO 14.6) were investigated in vitro (29 degrees C, pH 7.40, Ca2+ 2.5 mM; stimulation frequency, 3/min) under low (isotony) and high (isometry) load. Data are mean percentages of baseline +/- SD.

RESULTS

Desflurane induced no significant inotropic effect in healthy muscles (maximum unloaded shortening velocity and isometric active force at 9.4 vol%: 97 +/- 9% and 92 +/- 20%, respectively). In contrast, in cardiomyopathic muscles, desflurane induced a moderate negative inotropic effect (maximum unloaded shortening velocity and active force at 9.4 vol%: 84 +/- 19% and 75 +/- 25%, respectively). The negative inotropic effect was more pronounced than that in healthy muscles under low (P < 0.05) but not high load, and even when concentrations were corrected for minimum alveolar concentrations in each strain. Adrenoceptor blockade or pretreatment with reserpine did not modify the inotropic effect of desflurane, suggesting the absence of intramyocardial catecholamine release. However, tyramine also did not induce any significant catecholamine release in hamster myocardium. In both strains, desflurane induced no significant lusitropic effect under low or high load.

CONCLUSIONS

Desflurane had no inotropic effect in healthy muscles and a moderate negative inotropic effect in cardiomyopathic muscles. The absence of desflurane-induced intramyocardial catecholamine release was related to hamster myocardium characteristics.

[Management of severe burns during the 1st 72 hours]

Early and efficient management of severely burned patients facilitates outcome improvement. Pre-hospital care includes fluid loading with 2 mL.kg-1/% burn over the first six hours, sedation and analgesia, prevention of hypothermia and ventilatory support for either critically burned patients or facial, cervical or pulmonary burn injury. The transient stay in a general hospital before transfer to a burn centre allows extension of initial care, the critical investigation for associated injuries (intoxication, multiple trauma) and to perform initial local treatment with sterile coverage or vaseline gauze after a revised assessment of the burned skin area, and possibly escharotomies. The main aim of care in the burn centre is to control hypovolaemia and to obtain maximal tissue perfusion and oxygen delivery to burned tissues, as well as to healthy organs. To manage the burn shock (initially hypovolemic and later on hyperdynamic) catecholamines are often indicated when appropriate fluid loading remains insufficient. Mechanical ventilation is indicated in case of either a deep extensive burn over 60% of total body surface area, or facial and cervical burns or severe pulmonary burn injury from smoke inhalation, carbon monoxide intoxication, tracheobronchial thermal injury and blast injury. Because of the severity of burn-related pain, and the stimulus linked to intensive care, continuous sedation is usually required. Early surgical treatment such as escharotomies, excision and grafting, which cause significant pain as well as blood loss, and hydrotherapy, often require general anaesthesia. Burn injury can modify the volume of distribution and the pharmacokinetics of anaesthetic agents. Finally, chemical or electrical burn, radiation, associated CO intoxication or multiple trauma, as well as burn injury in infants, raise specific problems. With improvement in early intensive care, the survival rate of the most severely burned patients is obviously improving. New techniques in skin substitution will probably further improve the final outcome.

Early hemodynamic variations assessed by an echo-Doppler aortic blood flow device in a severely burned infant: correlation with the circulating cytokines

We describe the case of a seriously burned infant who suffered from a deep burn covering approximately 30% of his total body surface area. Because invasive hemodynamic monitoring is usually not suggested in infants, hemodynamic profile can be misunderstood. We tested a new echo-Doppler device to determine hemodynamic variation using a small esophageal probe specifically designed for newborns and infants. The aortic flowmeter was connected with satellite devices to obtain the hemodynamic profile, including aortic blood flow (ABF), preejection period, left ventricular ejection time, mean arterial pressure, heart rate, calculated stroke volume, calculated total systemic vascular resistance (TSVR), and end-tidal CO2 pressure. The positioning of the probe was easily obtained at each time. The hemodynamic management initially exhibited a hypovolemic status followed by a hyperdynamic profile, as suggested by a gradually increased ABF, which seemed similar to the variations currently reported in adult burn patients. Concurrent with hemodynamic determinations, plasma samples were drawn to measure interleukin-6 (IL-6), interleukin-1beta(IL-1beta), and tumor necrosis factor-alpha(TNF-alpha)levels. A consistent peak of IL-6 occurred simultaneously with the drop in TSVR. In contrast, no marked modifications were observed with IL-1beta and TNF-alpha. The same circulating cytokines moved alike in burned adults; IL-6 could partly explain the mechanisms of hemodynamic variation through the systemic inflammatory response syndrome. On the other hand, the echo-Doppler device could provide valuable noninvasive findings, allowing early improvement in resuscitation during the acute phase of critically burned infants and children.

Comparison of the effects of sevoflurane, isoflurane and halothane on rat myocardium

The effects of sevoflurane on myocardial contraction and relaxation are poorly understood. Therefore, we studied the effects of equianaesthetic concentrations (0.5, 1, 1.5, 2 and 2.5 MAC) of sevoflurane, isoflurane and halothane on inotropic and lusitropic (myocardial relaxation) variables, and post-rest potentiation in rat left ventricular papillary muscles in vitro. Sevoflurane and isoflurane caused comparable concentration-dependent negative inotropic effects which were significantly lower than those induced by halothane (P < 0.05). Sevoflurane and isoflurane did not modify lusitropic variables under low or high load, whereas halothane showed a negative lusitropic effect at high concentrations. Halothane suppressed post-rest potentiation, whereas isoflurane and sevoflurane did not. Post-rest recovery was unaffected by halothane, isoflurane or sevoflurane at any concentration. Thus in rat myocardium, sevoflurane and isoflurane caused comparable negative inotropic effects, had no significant lusitropic effects and did not alter post-rest potentiation, suggesting that they did not significantly modify the functions of the sarcoplasmic reticulum.

Interaction of isoflurane and sevoflurane with alpha- and beta-adrenoceptor stimulations in rat myocardium

BACKGROUND

Halothane potentiates the positive inotropic effects of alpha- and beta-adrenoceptor stimulations but impairs the positive lusitropic effect of beta-adrenoceptor stimulations. However, the interactions of isoflurane and sevoflurane with alpha- and beta-adrenoceptor stimulation have not been entirely defined.

METHODS

The effects of 1 minimum alveolar concentration isoflurane and sevoflurane on the inotropic responses induced by phenylephrine (10(-8) to 10(-4) M) or isoproterenol (10(-8 to 10(-4) M) were studied in rat left ventricular papillary muscles in vitro (Krebs-Henseleit solution, 29 degrees C; pH, 7.4; 0.5 mM calcium; stimulation frequency, 12 pulses/min). The positive lusitropic effects of alpha- and beta-adrenoceptor stimulations were studied under isotonic and isometric conditions. Data are mean percentages of baseline +/- SEM.

RESULTS

In control groups, phenylephrine (134 +/- 8%; P < 0.05) and isoproterenol (171 +/- 7%; P < 0.05) induced a positive inotropic effect. Isoflurane enhanced the positive inotropic effects of phenylephrine (185 +/- 10%; P < 0.05) and of isoproterenol (203 +/- 11%; P < 0.05). Sevoflurane enhanced the positive inotropic effects of phenylephrine (187 +/- 10%; P < 0.05) and of isoproterenol (228 +/- 11%; P < 0.05). These potentiations were similar to those previously reported with halothane. Isoflurane and sevoflurane did not modify the positive lusitropic effects under low and high loads of isoproterenol.

CONCLUSION

Although isoflurane and sevoflurane have moderate negative inotropic effects, they potentiated the positive inotropic effects of alpha- and beta-adrenoceptor stimulations but did not modify the positive lusitropic effects of beta-adrenoceptor stimulation.

Myocardial effects of isoflurane in healthy infants and small children. Assessment by continuous oesophageal aortic blood flow echo-Doppler

BACKGROUND

In paediatric healthy patients and in real peroperative conditions, the cardiovascular effects of isoflurane have been poorly described.

METHODS

We have evaluated the myocardial effects of 1% end-expired concentration (EEC) of isoflurane in 25 healthy infants or small children undergoing superficial surgical therapy for small burns with a continuous aortic blood flow echo-Doppler device. Aortic blood flow (ABF) was measured with a small oesophageal probe specially designed for infants. The aortic flowmeter was connected with satellite devices to visualize the haemodynamic profile variations during the isoflurane inhalation period.

RESULTS

Isoflurane significantly decreased ABF and increased pre-ejection period/left ventricular ejection time (PEP/LVET), when compared with control values previously recorded 5 min after induction with halothane-fentanyl and atracurium (respectively, 80 +/- 7%, mean +/- SD; P < 0.001 and 111 +/- 11%; P = 0.017, 5 min after EEC of isoflurane reached 1%, then respectively, 75 +/- 12%; P < 0.001 and 119 +/- 16%; P < 0.001, at the end of the isoflurane inhalation period). These variations reversed to a great extent when isoflurane was switched off (97 +/- 17% for ABF; P = 0.08 and 105 +/- 12% for PEP/LVET; P = 0.75). Among the usual parameters, 1% EEC of isoflurane caused no significant changes in heart rate, moderately decreased mean arterial pressure (successively, 88 +/- 12%; P = 0.045 and 87 +/- 19%; P = 0.049), but belatedly decreased end-tidal CO2 pressure (87 +/- 11% at the end of the inhalation period (P < 0.001) which persisted 5 min after isoflurane was turned off (90 +/- 11%; P < 0.001)).

CONCLUSIONS

These findings suggest that isoflurane can transiently depress cardiac function in healthy infants.

The hemodynamic effects of pneumoperitoneum during laparoscopic surgery in healthy infants: assessment by continuous esophageal aortic blood flow echo-Doppler

Cardiovascular changes due to pneumoperitoneum during laparoscopic surgery are established in adult patients, but not known in infants. We investigated the hemodynamic effects of laparoscopy during general anesthesia in 12 ASA physical status I infants by using noninvasive continuous esophageal aortic blood flow (ABF) echo-Doppler monitoring. During the laparoscopic procedure, intraabdominal pressure was maintained automatically at 10 mm Hg by a CO2 insufflator, and minute ventilation was adjusted to avoid hypercapnia. Hemodynamic changes were continuously recorded on soft magnetic support and assessed at three time intervals: t0 (after the initiation of anesthesia), t1 (5 min after peritoneal insufflation), and t2 (5 min after exsufflation). The induction of pneumoperitoneum resulted in a significant decrease in ABF and stroke volume, and in a significant increase in systemic vascular resistance, compared with control values: 67% +/- 9% (P < 0.001), 68% +/- 10% (P < 0.001), and 162% +/- 34% (P < 0.001), respectively. These changes were completely reversed after peritoneal exsufflation. Pneumoperitoneum caused no significant changes in mean arterial pressure or in end-tidal CO2 pressure. These findings demonstrate that laparoscopy is associated with hemodynamic changes without clinically deleterious consequences in healthy infants during a short duration of pneumoperitoneum.

IMPLICATIONS

The peritoneal insufflation achieved during laparoscopic surgery is associated with cardiovascular impairments (decrease in cardiac performance and increase in vascular resistance). We found that these changes had no clinically deleterious effects in healthy infants.

Myocardial effects of halothane and isoflurane in hamsters with hypertrophic cardiomyopathy

BACKGROUND

The effects of halothane and isoflurane on myocardial contraction and relaxation in diseased myocardium are not completely understood.

METHODS

The effects of equianesthetic concentrations of halothane and isoflurane on inotropy and lusitropy in left ventricular papillary muscles of healthy hamsters and those with genetically induced cardiomyopathy (strain BIO 14.6) were investigated in vitro (29 degrees C; pH 7.40; Ca2+ 2.5 mM; stimulation frequency, 3/min) in isotonic and isometric conditions.

RESULTS

Halothane induced a negative inotropic effect that was greater in cardiomyopathic than in healthy hamsters (1.5 vol%, active isometric force (AF): 19 +/- 8% vs. 28 +/- 11% of control values; P < 0.05). Isoflurane induced a negative inotropic effect that was greater in cardiomyopathic than in healthy hamsters (2.0 vol%, AF: 64 +/- 13% vs. 75 +/- 11% of control values; P < 0.01). However, the negative inotropic effects of halothane and isoflurane were not different for cardiomyopathic or healthy hamsters when their concentrations were corrected for minimum alveolar concentration (MAC) values in each strain. Halothane induced a negative lusitropic effect under low load, which was more important in cardiomyopathic hamsters, suggesting a greater impairment in calcium uptake by the sarcoplasmic reticulum. In contrast, isoflurane induced a moderate positive lusitropic effect under low load in healthy but not in cardiomyopathic hamsters. Halothane and isoflurane induced no significant lusitropic effect under high load.

CONCLUSIONS

Halothane and isoflurane had greater negative inotropic effects in cardiomyopathic than in healthy hamsters. Nevertheless, no significant differences in their inotropic effects were noted when concentrations were correlated as a multiple of MAC in each strain.

Effects of desflurane in rat myocardium: comparison with isoflurane and halothane

BACKGROUND

The cardiovascular effects of desflurane have been investigated in several in vivo animal and human studies. To determine the possible contributions of myocardial depression, the effects of desflurane on various contractile parameters in isolated cardiac papillary muscles were compared with those of isoflurane and halothane.

METHODS

The effects of desflurane, isoflurane, and halothane (0.5-2.5 minimum alveolar concentration [MAC]) were studied in rat left ventricular papillary muscles (29 degrees C; pH 7.40; stimulation frequency, 12 pulses/min). The inotropic effects were compared under low (isotony) and high (isometry) loads, using the maximum unloaded shortening velocity (Vmax) and maximum isometric active force (AF). The lusitropic effects were compared in isotonic and isometric conditions.

RESULTS

Desflurane has no significant inotropic effect (AF at 2.5 MAC: 95 +/- 11% of control values; NS) in contrast with halothane and isoflurane (AF at 2.5 MAC: 37 +/- 14 vs. 65 +/- 10%, respectively; P < 0.05). After alpha- and beta-adrenoceptor blockade or pretreatment with reserpine, desflurane induced a negative inotropic effect (AF at 2.5 MAC: 83 +/- 11 vs. 89 +/- 8%, respectively) that was not significantly different from that of isoflurane (AF at 2.5 MAC: 80 +/- 12%). Halothane induced a negative lusitropic effect under low load, which was significantly greater than those of isoflurane and desflurane. In contrast to halothane, isoflurane and desflurane induced no significant lusitropic effect under high load and did not modify postrest potentiation. These results suggest that desflurane did not impair sarcoplasmic reticulum function.

CONCLUSIONS

When compared with isoflurane, desflurane induced a moderate positive inotropic effect related to intramyocardial catecholamine release. After adrenoceptor blockade, desflurane induced a negative inotropic effect comparable with that induced by isoflurane.

In the early stage of major burns, is there a correlation between survival, interleukin-6 levels and oxygen delivery and consumption?

The correlation between haemodynamic and oxymetric parameters, and circulating cytokines has been little studied for the early phase of extensive burns. The aim of this prospective study was to evaluate survival, looking at variations in cardiac index (CI), oxygen delivery (DO2I) and consumption (VO2I) indexed to the body surface area (BSA), and circulating interleukin-6 (IL6) levels in the acute stage of major burns. Over a 12-month period, all patients admitted within 6 h of extensive thermal injury with total burn surface area (TBSA) of over 60 per cent, necessitating standardized resuscitation and mechanical ventilation, were included. Routine intensive care monitoring, including pulmonary and femoral artery catheters, was set up. During the first 3 days post-injury haemodynamic and oxymetric profiles were recorded every 6 h. Circulating IL6 samples were taken within 6 h of admission, then daily (at 24, 48 and 72 h). A comparison of the results in survivors (S) and non-survivors (NS) at those previously determined times was made. Ten consecutive patients were studied. Six patients survived (Age = 33 +/- 10 years; TBSA = 76 +/- 11 per cent) and four died (Age = 40 +/- 14 years; TBSA = 77 +/- 13 per cent). Similar initial hypovolemic profiles were found in both groups. From 24 h, a hyperdynamic status was observed which increased until 72 h. This hyperkinetic evolution was more marked in the survivors (CI: 4.6 +/- 2.0 for NS and 6.9 +/- 1.51 min-1 m-2 for S; SVRI: 2125 +/- 1288 for NS and 918 +/- 232 dyne s cm-5 m2 for S at 72 h). DO2I and VO2I were always higher in the survivors. DO2I and VO2I increased from admission to 72 h in the survivors whereas a significant drop in DO2I and VO2I occurred in the non-survivors at 48 h (DO2I:536 +/- 222 for NS and 1228 +/- 268 ml min-1 m-2 for S; VO2I:120 +/- 50 for NS and 251 +/- 56 ml min-1 m-2 for S (P < 0.01)). Plasma IL6 revealed abnormal values with consistent peaks at 24-48 h in the survivors (respectively 17,411 +/- 24,542 and 10,746 +/- 11,802 pg ml-1) and only moderate peaks in the non-survivors (865 +/- 652 and 912 +/- 485 pg ml-1). Finally, CI, DO2I, VO2I and circulating IL6 were always higher, and SVRI lower, in the survivors than in the non-survivors. The ability to increase DO2 and to optimize VO2 during the 'turning point' of 48 h seems to improve the prognosis of critically burned patients: the role of IL6 in this systemic inflammatory response is discussed.

Continuous oesophageal aortic blood flow echo-Doppler measurement during general anaesthesia in infants

PURPOSE

Invasive haemodynamic monitoring during general anaesthesia in infants is usually limited to very high risk operations, such as cardiac surgery. Nevertheless, different surgical procedures and/or anaesthetic techniques justify additional monitoring for children, as for adults. The aim of this preliminary study was to evaluate the feasibility of using a new echo-Doppler device (Dynemo 3000) capable of measuring continuous aortic blood flow during general anaesthesia in infants.

METHODS

Aortic blood flow (ABF) was measured with a small oesophageal probe designed for newborns and infants. The aortic flowmeter was connected with satellite devices to visualise the haemodynamic profile which included ABF, pre-ejection period (PEPi), left ventricular ejection time (LVETi), mean arterial pressure, heart rate, stroke volume and systemic vascular resistance. Twelve infants, aged 8-26 mo, undergoing surgery under general anaesthesia were successively included in the evaluation of this device. Isoflurane (1% end-expired concentration) was introduced to maintain anaesthesia after induction with halothane, midazolam, fentanyl and atracurium.

RESULTS

Correct positioning of the probe was easily obtained in all cases and the recording quality was excellent, whatever the operative position. Recordings of haemodynamic data showed some myocardial depression from isoflurane: decreased ABF (indexed to body surface area) and lengthened PEP/LVET (2.24 +/- 0.53 L.min-1.m-2 and 0.32 +/- 0.05 respectively, before introduction of isoflurane and 1.71 +/ 0.53 L.min-1.m-2 (P = 0.027) and 0.39 +/- 0.06 (P = 0.007) with isoflurane).

CONCLUSION

These preliminary results suggest that this continuous ABF echo-Doppler device may be valuable for peri anaesthetic monitoring in infants.

[Electric burns: epidemiological and therapeutic aspects]

OBJECTIVES

A retrospective study of patients with electrical burns was conducted to choose criteria for initial dispatching and establish a treatment protocol for out patient management.

METHODS

The study included 67 patients injured by electrical current and admitted at Edouard Herriot Hospital Burns Unit between January 1st 1990 and January 1st 1993.

RESULTS

Low-voltage currents (< 1000 Volts) responsible for serious and immediate cardio-vascular diseases occurred in domestic accidents, mostly with children. High-voltage current (> 1000 Volts) responsible for deep burn injuries occurred in accidents at work and mostly with adults. Twenty-two were outpatients and 45 were admitted at once. Two died on admission, 24 were hospitalized less than five days, 11 required repeated surgical treatments and a long stay at hospital, and 8 were severely burned and were admitted to the intensive-care unit. Two required continuous venovenous hemodialysis for three weeks. Morbidity of the last three groups was nil, morbidity remained high in term of functional and aesthetic after-effects.

CONCLUSION

Information on prevention of electrical burns should be intensified.

[Hemodynamic profile and serum cytokines in crush syndrome. Analogy with severe burns]

A 71-year-old woman remained under the rubble of her house for 4 hours after an accidental gas explosion. She suffered from a crush syndrome associating fractures, minor skin burns (< 10% body surface area), inhalation lung injury and moderate hypothermia (34 degrees C). In addition to local signs of compression of the lower limbs, the patient presented with hypovolemic shock and developed acute renal failure on day 3. We describe here the variations in hemodynamic and oxymetric parameters and cytokine response during the first post-injury week. A vasoplegic state resulting from low systemic vascular resistances with progressively increasing cardiac index, oxygen delivery and oxygen consumption closely followed the brief hypovolemic shock. Tumor necrosis factor-alpha remained below normal levels while interleukin-6 increased markedly with a major peak on day 2, in parallel with the drop in systemic vascular resistances. Interleukin-6 is a mediator of impairment in cell membrane function and a vasoconstriction inhibitor. Isolated increased interleukin-6 has been previously reported in severely burned patients suggesting a pathophysiological and hemodynamic similarity between crush syndrome and burn injury.

[Severe burnt patients: hemodynamic state, oxygen transport and consumption, plasma cytokines]

OBJECTIVE

To assess the haemodynamic and oxymetric variations measured by a pulmonary artery catheter and to correlate them with the variations of the circulating cytokines during the initial intensive care phase of severely burned patients.

STUDY DESIGN

Prospective study covering an 18-month period.

PATIENTS

Thirteen successive patients, aged over 12 years, without significant medical history, with a thermal burn affecting more than 50 percent of their total body surface area and admitted to our centre during the first six postburn hours.

METHODS

The haemodynamic and oxymetric profile was investigated by inserting a blood flow-directed balloon-tipped pulmonary artery fiberoptical catheter. All patients were treated according to the protocol previously used in our centre. Blood samples were drawn on admission, every 12 hours post-injury until the 2nd day, then on the 3rd and 5th days. Cytokines were analyzed by Elisa method. Haemodynamic and oxymetric measurements were achieved simultaneously with the biological samples during the first 5 postburn days. The analysis of variance (ANOVA) with the Duncan test was utilized for multiple comparisons between continuous variables.

RESULTS

(mean +/- SEM): The patients were 32 +/- 3 years-old and had a burn surface of 72 +/- 4%. After a short hypovolemic shock period lasting a 12 hours, a hyperdynamic shock occured which increased until the 5th day, with an increased cardiac index (6.9 +/- 0.4 at h120 vs 2.9 +/- 0.3 L.min-1.m-2 at h6, P < 0.05), increased oxygen transport and consumption (respectively 880 +/- 77 at h72 vs 543 +/- 58 mL.min-1 at h12, P < 0.05 and, 203 +/- 15 at h72 vs 129 +/- 25 mL.min-1 at h6, P < 0.05) and markedly decreased systemic vascular resistances (1,002 +/- 118 at h36 vs 2,330 +/- 328 dyn.s.cm-5.m2 at h6, P < 0.05). Circulating cytokines were not clearly modified except for interleukine-6 which reached early striking peaks (16,858 +/- 10,330 at h24 and 15,406 +/- 6,509 pg.mL-1 at h36) simultaneously with the decrease in systemic vascular resistances.

CONCLUSIONS

During the first post-injury week, critically burned patients develop a specific hyperdynamic circulatory status during which interleukine-6 could be a mainfactor decreasing systemic arterial resistances.

Non-invasive continuous haemodynamic and PETCO2 monitoring during peroperative cardiac arrest

We describe a cardiac arrest which occurred during general anaesthesia in the prone position for surgical correction of lumbar kyphosis in a patient with Marfan's syndrome. Peroperative monitoring was routine with ECG, non-invasive arterial pressure, oximetry, PETCO2 and central venous pressure, plus aortic blood flow and and systolic time intervals via an oesophageal echo-Doppler device. Forty-five minutes after the start of surgery, a sudden decrease in aortic blood flow followed by a decrease in PETCO2 suggested acute cardiac failure despite continuation of the ECG signal. Initial CPR in the prone position produced a slight increase in PETCO2. When the patient was turned to the supine position and the legs elevated, chest compression was more efficient and spontaneous circulation was rapidly restored. Circulatory arrest could be explained by incompletely treated hypovolaemia, or by myocardial depression (decrease in aortic blood flow and lengthened pre-ejection period) combined with excessive hypotension in a patient with Marfan's syndrome, thus compromising coronary blood flow producing ST segment depression. Continuous non-invasive aortic blood flow and PETCO2 monitoring proved valuable in the early detection and treatment of circulatory arrest and in the evaluation of the efficiency of peroperative CPR.

Standard doses versus repeated high doses of epinephrine in cardiac arrest outside the hospital

Among all of the cathecolamines used for cardiac arrest treatment, epinephrine injection during cardio-pulmonary resuscitation is currently the most powerful means of enhancing effectiveness; however, deliberations about the optimal dosage have recently become intense. In the SAMU of Lyon (F), we conducted a double blind prospective randomized study over an 18-month period, comparing repeated standard-dose epinephrine (1 mg) and repeated high-dose epinephrine (5 mg) in the management of cardiac arrest outside the hospital. Five-hundred thirty-six patients were enrolled with 265 in the standard-dose group and 271 in the high-dose group; both groups are globally similar. One-hundred eighty-one (33.8%) patients returned to spontaneous circulation (R.O.S.C.); 85 in the standard-dose group (32%) and 96 in the high-dose group (35.5%). One-hundred nineteen patients (22.2%) were admitted; 54 in the standard-dose group (20.4%) and 65 in the high-dose group (24%). At 6 months nine patients (7.6%) were alive; three patients from the standard-dose group (5.5%) and six from the high-dose group (9.2%). We never noticed cardiac or neurologic adverse effects with the high doses. The results of this study are not statistically significant, but we observed a marginal trend towards repeated 5 mg epinephrine doses. A large French multicentre study is now necessary.

[Diagnosis of heart arrest caused by CO2 embolism during laparoscopic surgery by monitoring of aortic blood flow and capnography]

We report the case of a 25-year-old woman undergoing a laparoscopic cholecystectomy, who suffered, one min after the beginning of intraperitoneal insufflation of CO2 (2.5 L at a pressure of 10 mmHg), a sudden decrease to 0.8 L.min-1 of the aortic blood flow (ABF), monitored in the descending aorta by an oesophageal echo-Doppler probe, associated with a decrease of PetCO2 to 15 mmHg and of SpO2 readings to 88%. Despite the lack of simultaneous changes in heart rate and arterial pressure, pulmonary gas embolism (GE) was suspected. The pneumoperitoneum was exsufflated and CPR was started because of circulatory inefficiency. Ten min later, efficient spontaneous cardiac activity restarted, whereas PetCO2 and ABF returned rapidly to normal values. At this time, a typical gas noise was clearly obtained through the oesophageal Doppler transducer. The patient remained in deep coma (GCS:6) with a left sided hemiplegia. However, she fully recovered after four sessions of hyperbaric oxygenation. Simultaneous continuous monitoring of ABF and PetCO2 allows an undelayed recognition of major circulatory disturbances, before significant changes in heart rate and arterial pressure occur.

Prognostic significance of early cardiac index measurements in severely burned patients

Invasive monitoring during early resuscitation was performed. To compare the heamodynamic results of severely burned patients, the results of 38 patients hospitalized between 1988 and 1991 in the burn centre of Lyon were retrospectively reviewed. Survivors and non-Survivors' data were compared. No difference existed between the two groups in age, unit burn score, fluid requirement and dose of dobutamine. Survivors had a significantly higher cardiac index, O2 delivery and systolic blood pressure index than non-survivors. It is suggested that the ability to sustain a high cardiac index in response to the burn injury plays a role in the outcome of the patients. There is an indication that dobutamine could have a beneficial effect in this way. Further studies are needed to confirm the benefit of the maintenance of high cardiac index levels by the pressors.

A dermal substrate made of collagen--GAG--chitosan for deep burn coverage: first clinical uses

In cases of severe burns, it seems necessary to excise burnt tissues as soon as possible and to cover the excised area immediately with a skin substitute, when few autografts are available. We report here the first clinical uses of a dermal substrate made of collagen--GAG--chitosan grafted immediately after early excision, then epidermalized either with autologous meshed autograft or with autologous cultured epidermis. The dermal substrate replaces the excised dermis by adhering to the underlying tissue, promoting fibrovascular ingrowth. Then after 15 days it can be epidermalized. The quality of the underlying dermis obtained permitted 100% take after epidermalization with large-meshed autograft, and tended to avoid the usual typical diamond aspect of the meshed skin. After epidermalization with autologous cultured autograft, the quality of the underlying dermis permits a good take. The best aspect is obtained by combining dermal substrate and autologous cultured epidermis. Even if it still does not replace the high quality of a homograft, this dermal substrate is a promising solution for replacement of dermis. It is always available, can be stored and is exempt from micro-organism transmission.

[Hemodynamic parameters in the severely burnt patient during the 1st 72 hours]

The haemodynamic time course of 16 patients with severe burn injury was investigated using a flow-directed balloon-tipped pulmonary artery catheter. The patients, aged 33.8 +/- 5.5 years, were burnt over 60 +/- 10% of body surface area, with a UBS score of 228 +/- 43. The measurements were obtained every six hours after insertion of the catheter. Fluid load was determined with Evans' formula, and modified according to the haemodynamic data. Catecholamines were introduced when this and a trial of fluid loading with 5 ml.kg-1 of macromolecules during a 20 min period had failed, starting with dobutamine or dopamine, followed by adrenaline as required. During the first hours after the injury, circulatory shock was partly linked to hypovolaemia: mean arterial pressure was 60.1 +/- 7.8 mmHg, right auricular pressure 4.5 +/- 2 mmHg, pulmonary wedge pressure 4.7 +/- 2 mmHg, cardiac index 3.5 +/- 0.8 l.min-1 x m-2. However, during the second and third days, cardiac output increased, with a cardiac index at 4.7 +/- 0.6 l.min-1 x m-2 and 5.2 +/- 0.2 l.min-1 x m-2 respectively, and arterial vascular resistances were decreased (536 +/- 125 dyn.s.cm-5). These data suggest a specific haemodynamic profile in severe burn patients which justifies invasive monitoring, and the use of catecholamines, in those patients that do not respond to fluid loading. The link between these data and the concomitant metabolic disturbances due to the burn injury has not yet been established. The increase in cardiac index could be related to the inflammatory response.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of early intracranial and cerebral perfusion pressures in post-cardiac arrest anoxic coma

The prognosis of prolonged cardiac arrests is generally related to brain damage due to the cerebral anoxia. A neurological worsening leading to irreversibility is sometimes associated with an increase in intracranial pressure. We studied for 5 years the early intracranial and cerebral perfusion pressures in 84 patients with deep anoxic coma after cardiac arrest. Intracranial pressure monitoring was set up as soon as possible with an extradural screw over a period of 6 days. No complications occurred using this technique. We recorded the percentage of patients suffering from intracranial pressure peaks over 15 mmHg (a), over 25 mmHg (b) or cerebral perfusion pressures drops under 50 mmHg (c). We obtained during the 1st day of monitoring: (a) 46.4%, (b) 21.4%, (c) 39%; during the 2nd day: (a) 73.6%, (b) 26.3%, (c) 55.9%. Eight patients (9.5%) were still alive after a couple of months, 4 of whom had no neurological sequelae; among the 76 non-survivors 63 (82.9%) had died because of cerebral anoxic damage. A daily comparison between survivors and non-survivors points out that the survivors' intracranial pressures were always lower than in the non-survivors and the survivors' cerebral perfusion pressures higher than in the non-survivors. Moreover, none of the patients showing intracranial peak pressures over 25 mmHg survived without after-effects. It is clear that many patients suffer early periods of high intracranial pressures and low cerebral perfusion pressures leading to a bad neurological prognosis. Intracranial pressure monitoring may allow assessment of patients' neurological status and prognosis after cardiac resuscitation.

Early effects of nimodipine on intracranial and cerebral perfusion pressures in cerebral anoxia after out-of-hospital cardiac arrest

Some calcium entry blockers seem to improve the neurological survival of anoxic comas. The early monitoring of intracranial pressure shows the frequency of intracranial hypertension. A calcium channel blocker has been shown to increase the cerebral blood flow which can potentially lead to deleterious increases of the intracranial pressure. This study presents 39 out-of-hospital cardiac arrests resuscitated with success. The intracranial pressures were registered by means of an extra dural screw set up as soon as possible. Nineteen patients received an early continuous 5 days nimodipine treatment (0.58 gamma/kg weight/min. after a 12.3 gamma/kg weight bolus). The other 20 patients did not receive any calcium entry blocker. The two groups were similar in terms of age, origin and electrical type of cardiac arrest, duration of cardiac arrest before BLS and before ACLS, principles of the treatment, initial neurological status and biological values. The maximum and mean intracranial pressures of the nimodipine group were always lower than the intracranial pressure of the control group. The cerebral perfusion pressure was never significantly different in both groups. If the nimodipine treatment proves to be efficient on neurological survival, it would be all the more interesting because it seems to limit the intracranial hypertension phenomenon which aggravates the neurological prognosis.