[Anaesthesia for a non cardiac surgery in a patient with an Eisenmenger syndrome. Interest of a non invasive haemodynamic monitoring]. / Anesthésie pour une chirurgie non cardiaque chez une patiente avec un syndrome d'Eisenmenger. Intérêt de la surveillance hémodynamique non invasive.

Patients with an Eisenmenger syndrome have an instuble hemodynamic status. During a general anaesthesia, the intracardiac shunt has to maintain the correct orientation and volume, adapted to each patient, in such a condition, to avoid the risk of hypoxemia and cardiac failure. The haemodynamic monitoring with a Swan Ganz catheter could be useful. But it is necessary to evaluate the advantage and the risks when the technique is used in these pathological circumstances. Moreover, when the cardiac output is measured with the thermodilution technique, the right-left intra cardiac shunt volume, is not taking into account. The continuous haemodynamic monitoring, with a simplified transoesophageal echo-Doppler system, as it was done in this case, allows appreciate the real quantitative variations of the shunt. In this way the more adequate calculation of some others haemodynamic parameters, over all the total systemic vascular resistances, allows a more precise therapeutic approach.

Endarterectomía carotídea bajo remifentanilo / Carotid endarterectomy under remifentanil

OBJETIVO. La endarterectomía carotídea puede realizarse bajo anestesia general o locorregional. En este último caso, el estado de consciencia del paciente permite una vigilancia clínica directa de la repercusión del pinzamiento vascular sobre el territorio neurológico correspondiente. Presentamos los resultados de un procedimiento anestésico mediante una analgesia pura con los pacientes intubados y ventilados, pero con un grado de conciencia suficiente como para vigilar los efectos del pinzamiento carotídeo sobre las funciones motrices.PACIENTES Y MÉTODO. Un grupo de 48 pacientes, ASA II-III, fue sometido a endarterectomía carotídea quirúrgica. El protocolo anestésico utilizado fue: preoxigenación durante 2 min. Inducción: remifentanilo 0,75-1 µg - kg-1 en 2 min, seguido de una perfusión de remifentanilo de 1 µg - kg-1 - min-1. Propofol, 1 mg - kg-1. Intubación orotraqueal: anestesia local de la glotis con nebulizador de lidocaína al 5 por ciento. Ventilación mecánica: FiO2 100 por ciento; FR, 12 min; VT, 8 ml - kg-1. Mantenimiento: la dosis de remifentanilo fue regulada para obtener una respuesta motriz coordinada (máximo, 1,5 µg - kg-1 - min-1; mínimo, 0,35 µg - kg-1 - min-1). Todos los pacientes se beneficiaron de una monitorización hemodinámica no invasiva continua, que comprendía la vigilancia del gasto aórtico por método eco-Doppler transesofágico.RESULTADOS. El objetivo de la anestesia fue alcanzado en todos los pacientes. Las alteraciones hemodinámicas más frecuentes fueron: bradicardia (28), hipotensión arterial (25), hipertensión arterial (3) y modificaciones del gasto aórtico. Todas estas modificaciones fueron rápidamente corregidas con la terapéutica utilizada, guiada por la evolución de los parámetros hemodinámicos. La recuperación postanestésica se obtuvo en menos de 4 min. En el postoperatorio sólo se observaron algunos episodios de hipertensión (12) e hipotensión arterial (1) leves, corregidos rápidamente. No hubo ninguna alteración debida a la inestabilidad hemodinámica. Durante la cirugía fue necesario utilizar un shunt intracarotídeo en un solo paciente. Tres pacientes presentaron complicaciones neurológicas postoperatorias ligadas a la cirugía. No hubo complicaciones imputables a la anestesia.DISCUSIÓN. Esta técnica presenta la ventaja de asegurar una duración no limitada de la anestesia, con una ventilación adecuada y manteniendo un estado de consciencia suficiente para la evaluación clínica de las repercusiones del pinzamiento carotídeo. La monitorización hemodinámica puso de manifiesto la aparición de desequilibrios que necesitaron corrección terapéutica. Se trata de un procedimiento que parece interesante, siempre que sea realizado con un protocolo estricto y con un seguimiento continuo, clínico e instrumental, de la evolución de los pacientes (AU)

Beta bloqueantes durante la anestesia general: esmolol para prevención de la isquemia miocárdica / Beta blockers during anesthesia: esmolol for prevention of myocardial ischemia

La prevención de la isquemia del miocardio es esencial durante la anestesia. Si definimos la isquemia miocárdica como la falla en el equilibrio entre el aporte y la demanda metabólica del O2 en los tejidos, pueden identificarse dos clases de isquemia: La isquemia absoluta, sin perfusión (hipotensión severa, con presión de perfusión cercana a cero y espasmo coronario prolongado) puede llevar a un daño celular irreversible, una vez establecido, no habrá lugar para la reversión. La isquemia relativa por inadecuado aporte de O2, pero suficiente para mantener temporalmente la viabilidad celular. Esta critica situación debe ser detectada y tratada con prontitud. El evento más frecuente es la taquicardia con un fuerte efecto ß1 positivo. Podemos bloquear este efecto con un beta bloqueador. En esta presentación se hace referencia a los ß bloqueadores, tipo Esmolol

[Carotid endarterectomy under remifentanil]. / Endarterectomía carotídea bajo remifentanilo.

OBJECTIVE: Carotid endarterectomy can be performed under general or locoregional anesthesia. If locoregional anesthesia is chosen, the state of awareness of the patient allows for direct viewing of the effect of vascular clamping of the corresponding neurological territory. We present the results of an anesthetic procedure using only an analgesic in patients who were intubated and ventilated but with a level of consciousness that allowed us to view the effect of carotid clamping on motor functions. METHOD: Forty-eight patients, ASA II-III, underwent surgical carotid endarterectomy. The anesthetic protocol began with preoxygenation for 2 min; induction with remifentanil 0.75-1 microgram kg-1 for 2 min., followed by perfusion of 1 microgram/kg-1.min-1 of remifentanil and propofol 1 microgram/kg-1; and orotracheal intubation by local anesthesia of the glottis with 5% lidocaine spray. Ventilation was with FiO2 100%, FR 12 min. and VT 8 ml. kg-1. For maintenance the dose of remifentanil was regulated to obtain a coordinated motor response (maximum 1.5 microgram/kg-1.min-1, minimum 0.35 microgram/kg-1. min-1). For all patients we monitored hemodynamics continuously and non-invasively, including aortic output by the transesophageal Doppler echocardiography. RESULTS: The objective of anesthesia was reached in all the patients. The most common hemodynamic alterations were bradycardia (28), arterial hypotension (25), elevated blood pressure (3) and altered aortic output. All changes were corrected quickly with the treatment used, guided by the evolution of hemodynamic parameters. Postanesthetic recovery came in less than 4 min. The only episodes of hyper -and hypotension consisted of a few episodes of mild hyper- (12) and hypotension (1), which were soon corrected. No alterations attributable to hemodynamic instability occurred. During surgery, an intracarotid shunt was necessary in only one patient. Three suffered surgically-related neurological complications after the operations. No complications could be attributed to anesthesia. DISCUSSION: An advantage of this technique is that the duration of anesthesia is not limited, with adequate ventilation and maintenance of an adequate state of consciousness for clinical evaluation of the repercussions of carotid clamping. Hemodynamic monitoring detected the appearance of imbalances requiring therapeutic intervention. The procedure is interesting provided it is performed according to a strict protocol, with continuous clinical and instrumental monitoring of the patient's status.

Haemodynamic changes during anaesthesia in knee-elbow position.

BACKGROUND: To evaluate hemodynamic alterations during surgical procedures performed in the knee-elbow position. DESIGN OF THE STUDY: prospective evaluation of the aortic blood flow (ABF) and other cardiovascular variables measured with a transesophageal Doppler (TED) in 2 groups of patients free of previous cardiovascular diseases undergoing lumbar discectomy. ENVIRONMENT: Operating theatre of a neurosurgical department. Beside TED, the standard monitoring included continuous ECG surveillance, capnometry, noninvasive measurement of blood pressure and pulsoxymetry. PATIENTS: Overall, 24 ASA 1 patients have been enrolled. In 12 patients (Group A) the intervention was performed without dobutamine. In the other 12 patients (Group B) dobutamine (2.5-3 micrograms/kg/min) was started from the beginning of the intervention; the two groups did not differ in terms of age, body size, duration of surgery or anesthetic technique used; hemodynamic measurements were obtained at the beginning of the intervention (T1), with the patients still supine, during the intervention in the knee-elbow position (T2) and finally at the end of the procedure (T3) being the patients still anesthetized but lying supine again. RESULTS: In both groups the ABF; the systolic volume and the ETCO2 significantly decreased in the knee-elbow position; concomitantly, peripheral vascular resistances increased. In Group B, the hemodynamic variables were significantly better than in the other group. CONCLUSIONS: In the patients enrolled, the perioperative administration of low-dose dobutamine was associated with better cardiovascular performance.

Detection of vascular haemodynamics through a high-speed velocity profiler.

OBJECTIVE: This paper aims at demonstrating that ultrasound Doppler multigate spectral analysis performed with advanced equipment may provide detailed and significant haemodynamic information. METHODS: A novel multigate system was recently introduced and shown capable of performing real-time spectral analysis of Doppler data from 64 resolution cells located at different depths from the transducer. The system extends the typical capabilities of conventional Pulsed Wave (PW) equipment by displaying the full spectral content of Doppler signals over an ultrasound scan line rather than in a single resolution cell. In cases where it is appropriate to display the available information in a simpler form, parameters such as the maximum frequency can be extracted from each spectrum, by using conventional or advanced image processing methods. RESULTS: In-vitro experiments show that the multigate system can perform velocity measurements with good accuracy and precision. Examples of in vivo profiles detected from carotid, femoral and radial arteries are presented. In particular, the first results obtained from the aorta are shown. CONCLUSIONS: Blood flow behavior can be accurately investigated using a real-time multigate system which extends Doppler spectral analysis to a whole scan line.

Measurements of systolic time intervals using a transoesophageal pulsed echo-Doppler.

Measurement of systolic time intervals (STI), an index of left ventricular (LV) systolic function, is usually labour intensive and requires considerable expertise to perform accurately. We have evaluated the accuracy of an automated, continuous and non-invasive STI measurement technique using a descending aortic blood velocity Doppler signal obtained using a transoesophageal echo-Doppler system (TEDS) and an ECG signal. STI were measured in adult pigs using a transoesophageal probe (4 x 4 mm pulsed wave Doppler transducer, 5-MHz frequency and a 3 x 3 mm echo transducer, 10-MHz frequency) associated with an ECG recorder. Measurements were performed at baseline and after injection of esmolol and dobutamine. TEDS data were compared with those obtained by one-line recordings of the electrocardiogram and the central aortic arterial pressure wave. Similar mean values were observed for pre-ejection period (PEPI), LV ejection time (LVET) and PEP/LVET with the two methods. Agreement between the methods (Bland and Altman's test) was excellent with 95% confidence intervals for PEP, LVET and PEP/LVET of -7.17 to +1.37 ms, -12.64 to +0.24 ms and -0.033 to +0.028, respectively. We conclude that the combination of descending aorta blood velocity Doppler and ECG signal is an alternative technique for non-invasive and objective measurement of STI, allowing continuous monitoring of LV systolic function.

Overestimation of low cardiac output measured by thermodilution.

We have investigated the influence of a cold water bolus (CWB) injection on overestimation of cardiac output (CO) in low CO states in anaesthetized dogs. CO was measured using three methods: (1) thermodilution (TD), (2) electromagnetic (EM) flow meter placed on the pulmonary artery and (3) transoesophageal echo-Doppler (OD) placed on the descending aorta. Measurements of CO were obtained before (steady state) and after induction of a low CO state with thiopentone 5 mg kg-1 i.v. After CWB injection, mean CO measured by EM and OD increased by 26% and 27%, respectively (P < 0.05) during steady state, and by 85% and 75% (P < 0.05) during the low CO state. This transient increase was produced by an increase in stroke volume, while heart rate did not change. Frank Starling's law may explain this variation by a sudden increase in preload produced by CWB injection. These results indicate that thermodilution overestimated CO during low CO states when CWB injection was used.

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.

[Detection of microbubbles formed in the blood/CO2 interphase during decompression in barometric conditions similar to laparoscopy]. / Detección de microburbujas formadas en la interfase sangre/CO2 durante la descompresión en condiciones barométricas similares a las de la laparoscopia.

HYPOTHESIS AND OBJECTIVES: Intraperitoneal insufflation (IPI) with CO2 during laparoscopic surgery establishes a pressure gradient that determines the passage of gas from the peritoneal cavity to the blood and surrounding tissues. The transport and clearance of CO2 are assured by proper sweeping when regional blood flow is adequate in volume and distribution. But if IPI hyperpressure surpasses regional venous capillary pressure (10 to 15 mmHg) and there is no cardio-circulatory adaptation to the phenomenon, CO2 clearance may be compromised. Under these conditions, the expected post-insufflation increase in PetCO2 will not take place. Bearing in mind the physical characteristics of CO2, retention of this gas in the intraperitoneal cavity produces blood and tissue saturation under a higher-than-atmospheric pressure, after a certain period of time in contact. Rapid intraperitoneal decompression after laparoscopic surgery carries with it the risk of microbubble formation due to release of CO2 that had been dissolved under hyperbaric conditions. MATERIAL AND METHODS: To test this hypothesis, the barometric conditions of laparoscopy were reproduced inside an observation capsule containing blood and CO2. RESULTS: Magnification revealed that after decompression bubbles formed in the blood/CO2 interphase. The images were recorded on magnetic videotape. Thirty minutes after decompression, the bubbles could still be seen, even after the interphase was swept with a current of air. DISCUSSION: Rapid intraperitoneal decompression after laparoscopy can generate the formation of microbubbles which, if not eliminated, will give rise to local ischemic manifestations. This same decompression, correcting the local circulatory alterations and activating the CO2 transport that had been compromised, could introduce gas bubbles into the blood stream such as are responsible for delayed gaseous microembolism. The simultaneous observation of changes in PetCO2 (stability or post-insufflation decreases) and hemodynamic parameters during laparoscopy, would allow evolving anomalies to be detected early and therapeutic action to be taken to prevent the formation of microbubbles.

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.

[Diagnosis of heart arrest caused by CO2 embolism during laparoscopic surgery by monitoring of aortic blood flow and capnography]. / Diagnostic par surveillance du débit aortique et du capnogramme d'un arrêt circulatoire par embolie de CO2 au cours de la chirurgie laparoscopique.

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.

[Improving tissue perfusion without invasive monitoring. Apropos of a case]. / Optimisation de la perfusion tissulaire obtenue sans monitorage invasif. A propos d'un cas.

A case is reported of a 64 year old patient who suffered a septic shock after surgical treatment of a biliary peritonitis. Increasing myocardial contractility and aortic blood flow by dobutamine appeared ineffective; added norepinephrine infusion improved the peripheral perfusion. This clinical improvement in tissue perfusion was evaluated by non-invasive continuous monitoring of the haemodynamic profile, combining aortic blood flow measurement by a transoesophageal echo-Doppler and continuous measurement of end-tidal carbon dioxide.