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Biomedical subjects

P Ravussin

Publications and source records attributed to P Ravussin.

At least 19 recordsLinked to original sources
PubMed1998

[Minimally invasive surgery for coronary disease: a new alternative].

To avoid the inflammatory syndrome generated by cardiopulmonary bypass, a new surgical technique, minimal invasive direct coronary artery bypass (MIDCAB), has been developed. An anastomosis is performed between the left internal mammary artery (LIMA) and the left anterior descending artery (LAD) on a beating heart, through a limited anterior thoracotomy. We describe our experience with this technique. Ten consecutive patients underwent a MIDCAB procedure. (9 males, age 65.9 +/- 9 years). There were 8 bypasses of the LIMA on the LAD, one bilateral mammary bypass on the LAD and the right coronary artery, and one conversion to a standard sternotomy with CPB for a saphenous vein bypass on the LAD because of injury to the LIMA (2nd case). There was one redo for haemostasis of the mammary artery bed (3rd case). The first 3 patients required postoperative blood transfusion. From the 4th operation onwards, with the introduction of new instrumentation which was better adapted to the narrowness of the surgical field, there were no further surgical complications. During the follow-up (mean 5 months; range 2-9), no patient suffered anginal recurrence. With the improvement of instrumentation, the MIDCAB technique offers satisfactory short- and mid-term results, while avoiding CPB with its adverse effects. Lastly, the cosmetic result is far better than with the conventional procedure.

Aged↗
PubMed1998

-The effect of ondansetron on intracranial pressure and cerebral perfusion pressure in neurosurgical patients-.

OBJECTIVE: To determine the effect of ondansetron on intracranial pressure (ICP), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP). STUDY DESIGN: Prospective, comparative, randomized double-blind study. PATIENTS: Twenty-six patients undergoing intracranial surgery. METHOD: Induction was obtained with propofol (1-2.5 mg.kg-1), fentanyl (1.5 micrograms.kg-1) and pancuronium (0.1 mg.kg-1), and maintenance was achieved with propofol and fentanyl. Intermittent positive pressure ventilation was used to ensure mild hypocapnia at 35 +/- 2 mmHg. Positioning of the patient was followed by 15 minutes steady-state. Patient received thereafter either 8 mg ondansetron or a placebo intravenously. The ICP was measured using a lumbar malleable spinal needle. CPP was calculated using the formula CCP = MAP-ICP. All variables were measured every minute for 15 minutes. RESULTS: The ICP, MAP and CPP did not differ between the two groups. There were no differences in the highest ICP values in patients receiving either ondansetron or placebo (11 +/- 5 versus 9 +/- 5, mean +/- SD), respectively. CONCLUSION: Intravenous administration of 8 mg ondansetron affects neither cerebral hemodynamics nor ICP.

Adolescent↗
PubMed1998

[The effect of position on intracranial pressure].

The question as to whether the head and trunk of neurosurgery patients should be elevated remains controversial. This question is particularly important when intracranial hypertension is present. Head up position may have beneficial effects on intracranial pressure (ICP) via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and cerebro spinal fluid displacement. However, in some circumstances, head up position may decrease MAP which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30 degrees should be avoided in all cases. In most patients with intracranial hypertension, head and trunk elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of at least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus the most important factor in assessment and monitoring when considering head elevation in patients with increased ICP.

Humans↗
PubMed1998

[Perioperative effects of the prone position: anesthesiologic aspects].

The prone position is commonly used for surgery of the spine and the posterior fossa, and is well tolerated by the majority of patients. As long as the abdomen is not compressed, the physiologic impact of this position on cardiorespiratory function is minor, in some cases even less than with the supine position. However extremes of position, particularly of the head and neck, are poorly tolerated and may lead to a variety of severe neurological complications. In addition, several specific forms of pre-existing pathology may predispose the prone patient to major cardiorespiratory complications. In this paper we have systematically reviewed the English and French literature from 1991 to 1997 using Medline Search of peer reviewed journals for the search terms "prone position" and "prone position and venous air embolism". The 330 collected references were reviewed for quality. In combination with review of current standard textbooks these references form the basis for the current report.

Anesthesia↗
PubMed1997

Anaesthesia for tracheal resection: report of 17 cases.

PURPOSE: Laryngo-tracheal stenosis remains a major complication after prolonged intubation or tracheostomy. Surgical resection with end-to-end anastomosis carries the best long term prognosis. For the anaesthetist, however, this procedure represents a most challenging situation. METHODS: Since 1993, we have used high frequency jet ventilation (HFJV) for tracheal resection. This paper describes the technique and the results of our series including 7 adults and 10 children. RESULTS: There were no adverse haemodynamic or ventilatory consequences due to HFJV. Oxygenation was well maintained during the HFJV period. Sixteen of the 17 patients had a good outcome. Despite the good result of the resection-anastomosis, one child still suffers from an associated posterior glottic stenosis. CONCLUSION: Since the introduction of HFJV for surgery of tracheal stenosis in our institution no complication of this ventilatory technique has occurred. It reduces the manipulation of the ventilation system and the period of apnea, thus decreasing the risk of hypoxaemia. The good access to the surgical field contributes to the success of resection-anastomoses in laryngo-tracheal stenosis.

Adult↗
PubMed1997

[Biomechanics and intracranial hypertension].

Biomechanics can be defined as the physical concepts exploring the effects of mechanical forces in biology. Biomechanics explores the consequences of an alteration in the steady-state normally existing between living tissues and their immediate environment. The application of this science in the field of brain physiopathology and intracranial hypertension is essential to understanding the sequence of events triggered during an alteration of the intracranial volume such as observed with intracranial pathologies. Furthermore, biomechanics allows the development of a logical and rational therapeutic approach, better adapted to the various intracerebral problems anaesthesiologists might be confronted with.

Adult↗
PubMed1997

[Cerebral hemodynamics and intracranial hypertension].

Various cerebral aggressions, either primary or secondary, can lead to the development of raised intracranial pressure. The presence of an elevated intracranial pressure often results in cerebral ischaemia/hypoxia and, eventually, neuronal death. In face of this cascade of events, several therapeutic approaches have been suggested. Two management concepts for patients with raised intracranial pressure have retained the most attention in recent years: the first suggests a therapeutic increase in cerebral perfusion pressure with the objectives to improve perilesional collateral perfusion and decreased cerebral blood volume, and consequently intracranial pressure in areas where autoregulation is preserved. The second concept supports the diminution in perilesional capillary pressure with the aim of decreasing vasogenic oedema. Although these two concepts are antagonistic and cannot be used simultaneously, they are probably complementary in the sequence of therapeutic events of patients experiencing severe head injury. This article reviews these therapeutic concepts and their clinical applications.

Anesthetics, Intravenous↗
PubMed1997

[Treatment of intracranial hypertension in the case of severe craniocerebral injuries].

More than 50% of severely head-injured patients develop increased intracranial pressure, risking exacerbating ischaemic insults to the already injured brain. In approximately 10% of these cases, intracranial pressure may become unresponsive to medical or surgical treatment, with a resulting mortality of over 90%. The main emphasis should be on full intensive care, based on the prophylaxis of the devastating effects of secondary insults to the injured brain. Specific treatment should be directed towards controlling intracranial pressure and maintaining a cerebral perfusion pressure over 70 mmHg, while avoiding, where feasible, treatment modalities at risk of exacerbating cerebral ischaemia. Recently, an algorithm for treating intracranial hypertension under three different therapeutic situations has been suggested, based on the successive application of effective agents with increasing associated risks. Therapeutic modalities of this protocol are discussed.

Algorithms↗
PubMed1997

Etomidate and thiopental-based anesthetic induction: comparisons between different titrated levels of electrophysiologic cortical depression and response to laryngoscopy.

STUDY OBJECTIVE: To determine whether etomidate-based induction can provide better hemodynamics than a standard thiopental sodium-based anesthetic induction. DESIGN: Prospective, single-blind clinical trial. SETTING: Multicenter university neurosurgical operating room. PATIENTS: 66 ASA physical status II and III inpatients undergoing neurosurgical procedures for intracranial tumor or other pathology. INTERVENTIONS: Patients were divided into two groups for anesthetic induction. The first group (control) was divided into two subgroups, with the first subgroup receiving "low-dose" etomidate (LET) 0.4 to 0.6 mg/kg titrated to an electroencephalographic (EEG) spectral edge frequency (SEF) of 10 to 12 Hz. The second subgroup received thiopental sodium (THIO) 3 to 6 mg/kg titrated to the same EEG endpoint. The study group was given high-dose etomidate (HET) 0.5 to 1.7 mg/kg titrated to an early burst suppression pattern. MEASUREMENTS AND MAIN RESULTS: Baseline (awake) measurements of mean arterial pressure (MAP) heart rate (HR), and SEF were obtained prior to anesthetic induction that was accomplished using a small bolus plus an infusion of the induction drug titrated to the EEG target. MAP, HR, and SEF were recorded just prior to laryngoscopy and intubation (T1), 30 seconds after laryngoscopy and intubation (T2), and 90 seconds after (T3) laryngoscopy and intubation. Times to reach EEG endpoint, along with total dose of anesthetic given, were also recorded. Compared with baseline values, the THIO group had the highest increase in both HR (22.9 +/- 4.4 bpm.) and MAP (16.8 +/- 4.2 mmHg) (P < 0.05) after laryngoscopy and intubation. The LET group also had significant increases compared with the HET group that demonstrated the least hemodynamic variability. No correlations could be made between age and dose of induction drug. CONCLUSIONS: Etomidate-based anesthetic induction, titrated to EEG burst suppression, produced stable hemodynamics during laryngoscopy and intubation as compared with lower dose, more "classic" inductions with etomidate or thiopental.

Adult↗
PubMed1997

The effect of skull-pin insertion on cerebrospinal fluid pressure and cerebral perfusion pressure: influence of sufentanil and fentanyl.

This randomized prospective study measured the effects of an intravenous opioid bolus on cerebrospinal fluid pressure (CSFP), mean arterial pressure (MAP), and cerebral perfusion pressure (CPP) during skull-pin insertion. Twenty-two adult patients scheduled for elective craniotomy for supratentorial lesions were studied. Outcome variables were MAP, heart rate (HR), and lumbar CSFP. The standardized anesthetic regimen included fentanyl (2 microg/kg), thiopental (5-7 mg/kg), lidocaine (1.5 mg/kg), isoflurane (0.3-0.7 minimum alveolar anesthetic concentration), and vecuronium (0.1 mg/kg). During stable anesthesia, sufentanil (0.8 microg/kg) or fentanyl (4.5 microg/kg) was given as a bolus before skull-pin insertion. The hemodynamic effects of the opioid injection were modified with phenylephrine and/or atropine when indicated. CSFP remained unchanged in both treatment groups. MAP and CPP increased approximately 10 mm Hg after skull-pin insertion (P<0.001). In the sufentanil group, HR decreased approximately 10 bpm after opioid injection and remained decreased throughout the study. In fentanyl-treated patients, HR decreased 8 bpm after opioid injection but returned to preopioid rates after skull-pin insertion. In conclusion, in anesthetized patients, an intravenous bolus of fentanyl or sufentanil prior to skull-pin insertion results in stable values of CSFP, CPP, BP, and HR when the hemodynamic effects of the opioid are modified with phenylephrine and atropine.

Adjuvants, Anesthesia↗