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S Dalmas

Publications and source records attributed to S Dalmas.

15 recordsLinked to original sources
PubMed1997

Effects and interactions of nitrous oxide, myocardial ischemia, and reperfusion on left ventricular diastolic function.

The effects of nitrous oxide on left ventricular diastolic function and its potential interactions with ischemia-induced diastolic dysfunction have not been described. Accordingly, we investigated the effects of nitrous oxide in ischemic and remote nonischemic myocardium during baseline, 90 min severe low-flow myocardial ischemia (systolic bulge), and reperfusion in 11 open-chest dogs. Anesthesia was maintained with fentanyl infusion (2 micrograms.kg-1.min-1), animals were ventilated with 60% nitrogen in oxygen, and hemodynamic variables were recorded prior to and after the replacement of nitrogen by 60% nitrous oxide. During baseline, nitrous oxide moderately increased chamber stiffness (+ 10%), myocardial stiffness (+33%), and unstressed length (+4%) and decreased the peak lengthening rate (-10%). Moreover, nitrous oxide decreased regional contractility during baseline (-12% at apex, -8% at base) as well as in nonischemic myocardium during myocardial ischemia (-9%) and reperfusion (-8%). However, nitrous oxide did not modify ischemia-induced systolic or diastolic dysfunction in ischemic myocardium during ischemia and reperfusion. Myocardial ischemia (+45%) and reperfusion (+57%) were associated with an increase in myocardial stiffness of nonischemic myocardium regardless of the anesthetic technique used. This study is the first to demonstrate that in addition to its well established negative inotropic effect, nitrous oxide affects regional diastolic function.

Anesthetics, Inhalation↗
PubMed1996

Effects and interactions of myocardial ischaemia and alterations in circulating blood volume on canine left ventricular diastolic function.

We have determined the effects of alterations in preload on ischaemia-induced diastolic dysfunction in anaesthetized beagles instrumented to measure left ventricular pressure and regional dimensions. Low-flow regional ischaemia decreased peak lengthening rates in ischaemic (mean -26 (SEM 6) mm s-1, P < 0.01) and non-ischaemic (-8.6 (3.4) mm s-1, P < 0.05) myocardium. Peak lengthening rates and the time constant of iso-volumic relaxation (tau) were not affected by alterations in preload. Absolute values of tau failed to distinguish between ischaemia and control. The ischaemia-induced decrease in peak negative dP/dt was preload dependent and caused mainly by a concomitant decrease in peak left ventricular pressure. We conclude that indices derived from segmental lengthening are sensitive to ischaemia and insensitive to preload, in contrast with indices derived from left ventricular pressure. It remains to be determined if monitoring of early segmental lengthening will improve detection and assessment of perioperative myocardial ischaemia.

Animals↗
PubMed1996

Myocardial ischemia and reperfusion are associated with an increased stiffness of remote nonischemic myocardium.

During and after an ischemic injury, maintenance and recovery of cardiac function may critically depend on remote nonischemic myocardium. Graded myocardial ischemia is associated with an approximately 50% increase in stiffness of nonischemic myocardium. We determined whether this increase in stiffness is unique to the ischemic period or persists during reperfusion. Ten anesthetized (isoflurane 1.0% vol/vol) open-chest dogs were instrumented to measure left ventricular pressure and dimensions (sonomicrometry) in ischemic and nonischemic myocardium. Regional chamber stiffness and myocardial stiffness were assessed using the end-diastolic pressure-length relationship which was modified by stepwise infusion and withdrawal of 200 mL of the animals' own blood during baseline, 45 min low flow ischemia (systolic bulge), and 60 min after the onset of reperfusion. In remote nonischemic myocardium, regional myocardial ischemia was associated with a significant (P < 0.05) increase in chamber stiffness (+44%) and myocardial stiffness (+48%). Sixty minutes after the onset of reperfusion, chamber stiffness (+54%, P < 0.05 versus baseline) and myocardial stiffness (+55%, P < 0.05 versus baseline) remained increased. Thus, the ischemia-induced increase in stiffness of remote nonischemic myocardium persists for at least 60 min after reperfusion.

Animals↗
PubMed1995

The influence of preload on post-systolic shortening in ischaemic myocardium.

Post-systolic shortening is a wall motion abnormality defined as shortening of cardiac muscle after the end of ejection and usually regarded as a manifestation of ischaemia. This study was designed to determine whether changes in preload may alter the magnitude of ischaemia-induced post-systolic shortening. Eleven beagles were anaesthetized (halothane 0.8%) and instrumented for measurement of pressures, flows and dimensions in the apical subendocardium supplied by the left anterior descending coronary artery. Myocardial ischaemia was obtained by tightening a micrometer-controlled snare around the left anterior descending coronary artery. Post-systolic shortening, calculated as end-systolic length minus minimum length divided by end-systolic length, was measured at different levels of preload. Increasing the preload from 4 to 17 mmHg caused a significant reduction in post-systolic shortening (8.9% vs. 12.9%, P < 0.05, Student's paired t-test); post-systolic shortening was negatively correlated with coronary perfusion pressure (r = 0.35, P < 0.01) and positively correlated with systolic bulging. This study demonstrates that the amount of post-systolic shortening depends on the volume status, which therefore has to be taken into account in interpreting regional wall motion abnormalities, such as those detected by echocardiography.

Animals↗
PubMed1995

[A study of blood loss during surgery for scoliosis. Posterior approach in 319 adolescents].

A retrospective study including 319 patients was realized from 1984 to 1993 in order to evaluate during scoliosis surgery the incidence on bleeding of the type of scoliosis and the anesthetic procedure. Blood losses were below one litre thus reducing the homologous blood transfusions. The patient was in prone position on a modified Wilson frame which facilitates venous return from the dorsal region. A moderate controlled hypotension was realized by combination of halothane, intravenous nitroglycerin (NG) and beta-blocking drugs (when required). Somatosensory evoked potentials were continuously monitored during surgery. A compression of the dorsal region was realized postoperatively in order to reduce blood loss. The blood losses were compared using Student's t-test. The mean perioperative bleeding was 9.8 ml.kg-1 for idiopathic scoliosis (no transfusion required), 14.1 ml.kg-1 for secondary scoliosis (p < 0.05 vs idiopathic) and 29.3 ml.kg-1 for neuromyopathic scoliosis (p < 0.05 vs idiopathic), indicating a major influence of muscle atonia on bleeding. The moderate controlled hypotension by iterative injection of NG and beta-adrenergic blocking drugs provided a safe and reversible hypotension.

Adolescent↗
PubMed1994

Response of atrial natriuretic factor to surgical pericardial drainage in patients with chronic pericardial effusion.

Previous studies have demonstrated the importance of atrial transmural pressure in the secretion of atrial natriuretic peptide. These studies have been performed in patients with pericardial effusion and hemodynamic compromise. The response of atrial natriuretic peptide to the drainage of chronic pericardial effusion without clinical evidence of tamponade is unknown. We studied 13 patients with chronic abundant pericardial effusion but without hemodynamic compromise. Blood samples for hormonal determinations were drawn before and after surgical pericardiocentesis. Right atrial pressure was measured during the procedure. Drainage induced a significant increase of atrial natriuretic peptide (from 12 +/- 3.9 to 105 +/- 22.8 pmol/l, P < 0.001, mean +/- S.E.M.), correlated with the fall in right atrial pressure (from 7.65 +/- 1.18 to 4.31 +/- 1.46 mmHg, P < 0.05, r = 0.68, P = 0.01). This increase was inversely correlated with the rise of mean blood pressure after surgery (from 84 +/- 2.37 to 100 +/- 5.3 mmHg, P < 0.05, r = 0.65, P < 0.02). Plasma renin activity decreased after drainage (from 8.12 +/- 2.57 to 3.27 +/- 0.65 ng/ml/h, P < 0.05). Surgery induced an increase of plasma levels of aldosterone (from 811 +/- 241 to 1199 +/- 249 pmol/l, P < 0.05), which were reduced after pericardiocentesis (371 +/- 102 pmol/l, P < 0.02). In patients with chronic abundant pericardial effusion, surgical pericardiocentesis induced a significant increase of atrial natriuretic peptide, correlated with a fall in right atrial pressure. The increase of atrial natriuretic peptide was similar than in patients with tamponade, despite a moderate fall in right atrial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Post-ischemic diastolic dysfunction.

Though a sustained post-ischemic decrease in contractile function has been clearly established, post-ischemic diastolic function has not been thoroughly investigated. Accordingly, 11 anesthetized (isoflurane 1%) open-chest beagles were instrumented to measure left ventricular pressure and dimensions (circumferential length and wall thickness) in an apicoanterior area supplied by the left anterior descending coronary artery (LAD). Pressure-dimension relations were modified by stepwise infusion and withdrawal of 200 mL of the animals' own blood during baseline, 45 minutes partial occlusion of the LAD (systolic bulging), and 60 minutes after the onset of reperfusion. Stiffness constants were derived from the end-diastolic pressure-length and stress-strain relations, respectively. Myocardial ischemia was associated with significant (P < 0.05) alterations of the following parameters of diastolic function: (1) 47% increase in end-diastolic pressure; (2) 22% decrease in peak negative dP/dt; (3) 9% increase in the time constant of isovolumic relaxation (tau); (4) postcystolic contraction; (5) 6% increase in end-diastolic length and 10% decrease in end-diastolic thickness; (6) 12% increase in unstressed length (creep) and 13% decrease in unstressed thickness; (7) 51% increase in chamber stiffness and a 63% increase in myocardial stiffness; and (8) 40% decrease in the peak lengthening rate. After 60 minutes of reperfusion, only end-diastolic pressure and tau had returned to baseline values whereas systolic shortening fraction, postsystolic contraction, and end-diastolic and unstressed dimensions had only partially recovered. No recovery occurred in peak negative dP/dt, chamber stiffness, myocardial stiffness, and peak lengthening rate. Thus, both myocardial ischemia and reperfusion are associated with complex changes in global and regional left ventricular diastolic function.

Anesthesia, Inhalation↗
PubMed1994

[Cryoanesthesia by freon spray for venepuncture in children].

This prospective study was designed to assess the quality of skin analgesia provided by cryoanesthesia induced by a spray of freon (dichloro-tetrafluoro-ethane) for venous cannulation (22 or 24 Gauge cannulas). Eighty children between the ages of 5 and 15 years were allocated to two groups: 40 children had a conventional venepuncture, 40 others had a venepuncture under cryoanesthesia. The spray of freon was applied for ten seconds on the area of skin to be anaesthetised. The venous cannulation was carried out by an anaesthetist of the paediatric surgical unit. The intensity of pain at venepuncture was quantified with a visual analogic scale (range 0 to 100). The median values of the pain scores were 11.5 (0 to 50) in the cryoanesthesia group and 48 (11 to 75) in the control group respectively. It is concluded that freon spray provides a convenient analgesia for venepuncture in children aged 5-15 years.

Adolescent↗
PubMed1989

[Nociceptive flexion reflex. Principles and applications of the threshold determination].

The threshold for the pain flexion reflex in the lower limb can be used to determine the potency in man of analgesic drugs acting centrally. A new apparatus is, the "algometre", described. Bipolar electrical stimulation (5 stimuli of 1 ms over a period of 10 ms) is applied to the saphenous nerve just behind the external malleolus. An amplifier detects the muscle response (electromyogramme; EMG) at the muscle-tendon junction in the popliteal space; this occurs about 70-130 ms after the painful stimulus. The whole system is linked to a microcomputer. The EMG and EMG/intensity curves are displayed on a colour screen, and can be copied by a colour tracing table. The whole machine is mobile and can be moved from bed to bed. An increase in the threshold during inhalation of 50% nitrous oxide in oxygen was shown. However, the usefulness of the "algometre" in clinical practice remains to be assessed by further studies.

Electric Stimulation↗
PubMed1989

[Resection and reconstruction of the carina with separate two-lung high-frequency jet ventilation].

Carinal resection and reconstruction via a right transpleural approach in an hypoxemic patient provides difficult maintenance of satisfactory gas exchange when one lung ventilation is inadequate. The present case report concerns a 62-year-old patient with chronic obstructive airways disease and a carinal squamous cell carcinoma. He underwent tracheobronchial reconstruction surgery by Barclay's procedure through a right postero-lateral thoracotomy. During resection and reconstruction phases, the gas exchange was maintained by a new technic: high-frequency-jet-ventilation (HFJV) with two small-bore catheters through the endotracheal tube and JVHF ventilators adjusted to the compliance of each lung (high for the right lung, low for the left one). No circulatory changes were observed during the sutures lines phase (90'). The oximeter and the arterial blood gas values show an adequate procedure. The immediate post operative period was unremarkable and uncomplicated. The histological diagnosis was squamous cell carcinoma involving the carina with one metastatic pretracheal lymph node and microscopic infiltration of the left main bronchus resection margin. Sixteen grays postoperative radiotherapy was required. Ten months after the patient is alive, without tumor recurrence. HFJV greatly facilitates surgery by avoiding endobronchial intubation with large cuffed tubes into the surgical field. In patients with low pulmonary reserve, bilateral lung HFJV is required: two JVHF ventilators with different ranges delivering separate ventilation to the right and left lungs avoid left hypoventilation and right surgical emphysema and insure good surgical conditions.

Anastomosis, Surgical↗