Patrick Ravussin

Complications of different ventilation strategies in endoscopic laryngeal surgery: a 10-year review.

Background:Spontaneous ventilation, mechanical controlled ventilation, apneic intermittent ventilation, and jet ventilation are commonly used during interventional suspension microlaryngoscopy. The aim of this study was to investigate specific complications of each technique, with special emphasis on transtracheal and transglottal jet ventilation. Methods:The authors performed a retrospective single-institution analysis of a case series of 1,093 microlaryngoscopies performed in 661 patients between January 1994 and January 2004. Data were collected from two separate prospective databases. Feasibility and complications encountered with each technique of ventilation were analyzed as main outcome measures. Results:During 1,093 suspension microlaryngoscopies, ventilation was supplied by mechanical controlled ventilation via small endotracheal tubes (n = 200), intermittent apneic ventilation (n = 159), transtracheal jet ventilation (n = 265), or transglottal jet ventilation (n = 469). Twenty-nine minor and 4 major complications occurred. Seventy-five percent of the patients with major events had an American Society of Anesthesiologists physical status classification of III. Five laryngospasms were observed with apneic intermittent ventilation. All other 24 complications (including 7 barotrauma) occurred during jet ventilation. Transtracheal jet ventilation was associated with a significantly higher complication rate than transglottal jet ventilation (P < 0.0001; odds ratio, 4.3 [95% confidence interval, 1.9–10.0]). All severe complications were related to barotraumas resulting from airway outflow obstruction during jet ventilation, most often laryngospasms. Conclusions:The use of a transtracheal cannula was the major independent risk factor for complications during jet ventilation for interventional microlaryngoscopy. The anesthetist’s vigilance in clinically detecting and preventing outflow airway obstruction remains the best prevention of barotrauma during subglottic jet ventilation.

A new transtracheal catheter for ventilation and resuscitation

We describe a new catheter for emergency ventilation of patients difficult to intubate. This catheter can be inserted through the crico-thyroid membrane or the first or second intertracheal ringspace with ease in an almost atraumatic fashion. The outside part of the device, with its dual attachment system, can be connected to conventional resuscitation equipment by its 15 mm male end or to a high-pressure oxygen source by its luer-lock fitting. A double angulation maintains the intratracheal portion of the catheter in the axis of the trachea and the external part in close contact with the larynx. A Velcro band attached to two lateral flanges keeps the catheter in place. The results of transtracheal catheterizalion of 48 patients by means of this new device are discussed.RésuméUn nouveau système de canulation transtrachéale ou transcrico-thyroidienne est présenté. Les multiples avantages qu’il procure sont a) sa mise en place rapide, b) sa connexion aisée, par son embout ISO 15 mm mâle etlou par son embout luer-lock femelle scellé en son milieu, à tout circuit d’anesthésie ou de réanimation, c) ses 2 ailettes, permettant une fixation solide autour du cou du patient et d) sa double angulation, assurant une position parallèle à la trachée et un positionnement adéquat contre le larynx du patient.Un total de 4S patients ayant été ventilés avec succès au moyen de ce cathéter est présenté. Les indications étaient les suivantes: a) patients difficiles à intuber: huit cas b) patients ayant déjà une fixation intermaxillaire associée à une fracture de la base etlou de la lame criblée; dix cas c) microlaryngoscopies en suspension avec laser: vingt cas d) endoscopies: dix cas.Vu les excellents résultats obtenus et la facilité d’administrer de l’oxygène par cette voie, on ne peut que souligner l’ importance d’avoir rapidement sous la main un cathéter transtrachéal et des connexions adéquates.

Conscious-sedation analgesia during craniotomy for intractable epilepsy: a review of 354 consecutive cases

The perioperative records of 354 consecutive patients undergoing craniotomy for surgical treatment of intractable epilepsy performed with conscious-sedation analgesia were reviewed retrospectively. There was no perioperative morbidity or mortality identified which could be attributed to the anaesthetic technique. The technique was not suitable for seven patients, in whom general anaesthesia was induced. The most frequent intraoperative problems were convulsions (16 per cent) and nausea and vomiting (eight per cent). Less frequent problems included excessive sedation (three per cent), “tight brain” (1.4 per cent) and local anaesthetic toxicity (two per cent). This study confirms that conscious-sedation analgesia provides suitable conditions for craniotomies when brain mapping is required.RésuméNous avons revisé les dossiers de 354 patients ayant subi une craniotomie pour exérese de tissue épileptogenique. Ľanesthésie employée est une technique de sedation et ďanalgésie. Une étudie rétrospective a été entreprise pour identifier les complications anesthésiques. Il n’y a pas eu de mortalité ou de morbidité secondaire à la technique ďanesthêsie. Sept patients n’ont pas toléré ľintervention et ľinduction ďanesthêsie genérale à été nécessaire chez ces patients. Les problèmes per-opératoires les plus fréquents ont été les convulsions (16 pour cent), les nausées et les vomissements (huit pour cent). Moins fréquemment, sont survenus de la s’dation excessive (trois pour cent), de ľengorgement du cerveau (un pour cent), et des réactions toxiques à ľanesthésique local (un pour cent). Le monitorage de la pression ďoxygène transcutanée chez 11 patients sans complications per-opératoires n’ à révélé aucun hypoxie durant les interventions.

Total intravenous anesthesia with propofol for burst suppression in cerebral aneurysm surgery: preliminary report of 42 patients.

Forty-two patients underwent cerebral aneurysm clipping at our institution in 1991, 35 with a ruptured aneurysm and 7 with an unruptured aneurysm. Preoperatively, 22 patients with a ruptured aneurysm were graded I or II according to the World Federation of Neurosurgical Societies and 21 underwent an operation on the first day. All underwent a standard cerebral protective general anesthesia, combining propofol with fentanyl, arterial normotension (mild hypertension with volume loading and/or dopamine during temporary clipping and once the aneurysm was secured), normocarbia or slight hypocarbia, brain relaxation with lumbar drainage, mannitol and propofol, and electroencephalogram burst suppression when temporary clipping (> or = 2 min) was required. Propofol doses for induction were 1.8 +/- 0.1 mg/kg (mean +/- standard error); for maintenance, doses were 86 +/- 3.5 micrograms/kg per min; and for burst suppression doses were 500 micrograms/kg per min. After clipping, the propofol dose rate was reduced to allow early recovery and neurological examination in the operating room. In 21 patients, temporary clipping was required for a mean duration of 8.8 +/- 1.3 minutes (range, 2-29); none of these patients deteriorated as compared with their preoperative neurological state. Twenty-four of the 42 patients (57%) had a Glasgow Coma Outcome Scale (GOS) score of 1, 7 patients had a GOS score of 2, 8 had a score of 3, and 3 had a score of 5. Thirty-two patients were extubated in the operating room with a mean GOS Score of 13.2 +/- 0.5, and 10 were extubated later in the intensive care unit.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transtracheal jet ventilation for paediatric endoscopic laser treatment of laryngeal and subglottic lesions

Percutaneous transtracheal high frequency jet ventilation (TTJV) in adults is frequently used during anaesthesia for laryngeal microsurgery. It provides excellent surgical operating conditions and safety for the patient. The technique has not been evaluated in infants and children. Accordingly, we studied 16 infants and children (mean age 5.5 ± 3.8 yr, range 6 wk–12 yr) who underwent 28 consecutive endoscopic procedures with laser microsurgery of the glottic or subglottic space under general anaesthesia using a TTJV technique. All patients had a severe obstructive lesion of the larynx and/or upper trachea. The mean duration of the procedure was 70 ± 27 min (range 30–140 min). Indications for TTJV were: subglottic stenosis: 5, haemangioma: 4, laryngeal papillomatosis: 5, pharyngeal cyst: 1, laryngomalacia: 1. Adequate control of the airway and satisfactory gas exchange were obtained in all cases. Surgery was performed without being impeded by anaesthetic equipment. Three complications occurred: one extensive surgical emphysema; one bilateral pneumothorax; one severe vagus-induced cardiovascular depression. Prompt and complete recovery without sequelae followed appropriate treatment. In 32% of the cases, the children were outpatients and in about half of the procedures (13/28) they left the hospital between the first and the third day. We conclude that percutaneous transtracheal jet ventilation is effective in paediatric endoscopic surgery. Procedures that might otherwise require a tracheostomy can be performed safely with this minimally invasive technique. Adequate indications and appropriate understanding of the technique and its potential problems are required for its correct application and successful use.RésuméLes avantages et inconvénients de la ventilation transtrachéale pour la chirurgie endoscopique au laser des voies aériennes supérieures sont bien connus chez l’adulte. Par contre l’intérêt de cette technique dans le traitement chirurgical au laser des pathologies glottiques ou sous-glottiques de l’enfant n’a pas encore été évalué. Dans ce but, nous avons étudié 16 patients âgés de 6 semaines à 12 ans (5,5 ± 3,8 ans), ayant nécessité 28 interventions endoscopiques pour le traitement d’une lésion obstructive sévère du larynx et/ou de la trachée supérieure, et chez qui une ventilation transtrachéale a été utilisée. La durée moyenne de l’intervention a été de 70 ± 27 min (30–140 min). Les indications de cette technique ont été: sténose sousglottique: 5, hémangiome sous-glottique: 4, papillomatose laryngée: 5, kyste pharyngé: 1, laryngomalacie: 1. Les principaux avantages de cette technique sont: un accès chirurgical libre de tout tube ou sonde endotrachéale, une visibilité optimalisée de l’endolarynx, un bon contrôle des voies aériennes, le maintien d’échanges gazeux satisfaisants, ainsi que l’élimination des dangers d’ignition du tube endotrachéal. Nous avons rencontré trois complications majeures: un emphysème sous-cutané important consécutif à la perforation accidentelle d’un cathéter par une aiguille chirurgicale; un barotraumatisme avec pneumothorax bilatéral lié à l’obstruction complète de la voie aérienne par une manipulation instrumentale; enfin, une bradycardie extrême avec arrêt circulatoire d’origine vagale au cours du positionnement d’une spatule de micro-laryngoscopie. Dans chacun de ces cas, l’instauration immédiate d’un traitement adéquat a permis une récupération rapide, complète et sans séquelles. Dans 32% des cas, les patients étaient ambulatoires, et dans presque la moitié des cas (13/28), ils ont quitté l’hôpital entre le 1er et le 3ème jour. A notre sens, la ventilation transtrachéale est une alternative valable et utile en chirurgie endoscopique pédiatrique; elle assure des conditions opératoires optimales et, dans certaines situations, permet d’éviter une trachéostomie avec ses risques de morbidité et de mortalité chez le nourrisson et le petit enfant. Néanmoins cette technique est plus invasive que l’intubation trachéale et ne doit pas être utilisée de routine. Le respect des indications et la connaissance appropriée de cette technique et de ses complications potentielles sont indispensables pour une utilisation efficace et sûre.

Propofol vs. thiopental-isoflurane for neurosurgical anesthesia: comparison of hemodynamics, CSF pressure, and recovery.

Sixty otherwise healthy patients with no clinical signs of intracranial hypertension who were undergoing elective intracranial surgery were randomly assigned to receive anesthesia with either thiopental, 3-6 mg/kg i.v., and isoflurane, 0.5-1.5% (group 1, N = 30) or propofol, 1-2.5 mg/kg i.v., and propofol infusion, 40-200 microg/kg/h (group 2, N = 30). Both groups received 50% nitrous oxide in O2 subsequent to dural opening. During induction, the changes in heart rate (HR), mean arterial pressure (MAP), cerebrospinal fluid pressure (CSFP), and cerebral perfusion pressure (CPP) were similar between the groups, except at 3 min when the findings (mean +/- SEM) for CPP (81 +/- 3.3 vs. 70.3 +/- 2.8 mm Hg, p <0.05) were significantly lower in group 2. At intubation, the highest level of MAP (103.1 +/- 3.3 vs. 88.9 +/- 2.7 mm Hg, p <0.05) was significantly greater in group 1. At pinhead-holder application, the highest values of HR (81.8 +/- 3 vs. 73.9 +/- 2.1 beats/min, p <0.05), MAP (112.2 +/- 3.6 vs. 98.3 +/- 3 mm Hg, p <0.05), CSFP (15.2 +/- 1.3 vs. 11.6 +/- 1.1 mm Hg, p <0.05), and CPP (97.0 +/- 3.9 vs. 86.7 +/- 3.3 mm Hg, p <0.05) were significantly greater in group 1. During early (20-30 min) recovery, group 2 had higher Glasgow Coma Scale scores and a greater percentage of patients in whom eye opening, response to commands, extubation, speech, and time/space orientation were present. In conclusion, when compared to thiopentalisoflurane for intracranial surgery, propofol produces similar HR, MAP, CSFP, and CPP responses during induction, adequate control of these responses during nociceptive stimulation, and faster recovery for cerebral function postoperatively.

Metabolic and hemodynamic changes during recovery and tracheal extubation in neurosurgical patients: immediate versus delayed recovery.

UNLABELLED Delayed recovery has been advocated to limit the postoperative stress linked to awakening from anesthesia, but data on this subject are lacking. In this study, we measured oxygen consumption (V(O2)) and plasma catecholamine concentrations as markers of postoperative stress. We tested the hypothesis that delayed recovery and extubation would attenuate metabolic changes after intracranial surgery. Thirty patients were included in a prospective, open study and were randomized into two groups. In Group I, the patients were tracheally extubated as soon as possible after surgery. In Group II, the patients were sedated with propofol for 2 h after surgery. V(O2), catecholamine concentration, mean arterial pressure (MAP), and heart rate (HR) were measured during anesthesia, at extubation, and 30 min after extubation. V(O2) and noradrenaline on extubation and mean V(O2) during recovery were significantly higher in Group II than in Group I (V(O2) for Group I: preextubation 215 +/- 46 mL/min, recovery 198 +/- 38 mL/min; for Group II: preextubation 320 +/- 75 mL/min, recovery 268 +/- 49 mL/min; noradrenaline on extubation for Group I: 207 +/- 76 pg/mL, for Group II: 374 +/- 236 pg/ mL). Extubation induced a significant increase in MAP. MAP, HR, and adrenaline values were not statistically different between groups. In conclusion, delayed recovery after neurosurgery cannot be recommended as a mechanism of limiting the metabolic and hemodynamic consequences from emergence from general anesthesia. IMPLICATIONS In this study, we tested the hypothesis that delayed recovery after neurosurgery would attenuate the consequences of recovery from general anesthesia. As markers of stress, oxygen consumption and noradrenaline blood levels were higher after delayed versus early recovery. Thus, delayed recovery cannot be recommended as a mechanism of limiting the metabolic and hemodynamic consequences from emergence after neurosurgery.

The effects of midazolam reversal by RO 15-1788 on cerebral perfusion pressure in patients with severe head injury

In patients with severe head injury, midazolam is a convenient agent for sedation during mechanical ventilation, although its sedative effect can be prolonged. We investigated the effects of acute midazolam reversal by RO 15-1788 (RO), a benzodiazepine antagonist, on intracranial pressure (ICP), cerebral perfusion pressure (CPP) and on recovery in 18 studies performed on 15 patients with severe head injury (Glasgow coma score<8). ICP increased significantly from 16.3 mmHg±2 (mean ±SEM) to 24.1 mmHg±4.2 (p<0.02) and to 25.2 mmHg±4 (p<0.01), 5 and 10 min respectively after RO administration. Analysis of the results showed 2 patterns of response in ICP. In patients with good control of ICP before RO administration, there was no change in ICP and CPP, whereas in patients with abnormal ICP, RO injection induced severe increase in ICP and concomitant decrease in CPP. Arousal after midazolam reversal was obvious in 5 patients who were quickly extubated. Midazolam reversal by RO should not be attempted in patients with severe head injury and unstable ICP.

The effects of bolus administration of opioids on cerebrospinal fluid pressure in patients with supratentorial lesions

In many studies reporting an increase in cerebrospinal fluid pressure (CSFP) after opioid administration, concomitant decreases in mean arterial pressure (MAP) have been observed.Autoregulatory cerebral vasodilation may therefore have been a factor in the CSFP increases. We tested the hypothesis that increases in CSFP after bolus injection of opioids could be minimized by modifying concomitant decreases in MAP with phenylephrine. Thirty-three patients with supratentorial mass lesions were studied in a randomized, prospective, double-blind, saline-controlled comparative trial. The principal outcome measures were lumbar CSFP, MAP, and heart rate (HR). Study drugs, sufentanil 0.8 micro gram/kg (n = 12), fentanyl 4.5 micro gram/kg (n = 11), or normal saline (n = 10), were injected intravenously (IV) during stable general anesthesia with 0.3-0.7 minimum alveolar anesthetic concentration (MAC) of isoflurane in oxygen and controlled ventilation (end-tidal carbon dioxide 32-35 mm Hg). Phenylephrine 50-100 micro gram was injected IV when MAP decreased by more than 15% of initial values, and atropine 0.5 mg IV when HR decreased to less than 45 bpm. Opioid administration was associated with significant decreases in MAP, 21 +/- 9 mm Hg (mean +/- SD) in the sufentanil group and 16 +/- 7 mm Hg in the fentanyl group; P < 0.001. These decreases in MAP were of short duration (i.e., corrected with 1-2 min). Patients in the sufentanil group needed more phenylephrine than patients in the fentanyl group (170 +/- 89 micro gram vs 100 +/- 47 micro gram; P < 0.05). No significant change in the CSFP was seen in either the sufentanil-(1 +/- 6 mm Hg) or fentanyl-treated patients (0 +/- 2 mm Hg). No significant changes in MAP or CSFP were observed in the saline-treated patients. HR decreased after injection of either study drug (P < 0.01) but remained unchanged in the saline group. In summary, during stable anesthesia with isoflurane in oxygen, bolus injections of fentanyl or sufentanil, despite producing rapidly corrected mean decreases in MAP of 18% and 25%, respectively, were not associated with any change in CSFP. (Anesth Analg 1996;82:600-6)

The effects of rapid infusions of saline and mannitol on cerebral blood volume and intracranial pressure in dogs.

The role of osmotic brain dehydration in the early reduction of intracranial pressure (1CP) following mannitol administration has recently been questioned and a decrease in cerebral blood volume (CBV) proposed as the mechanism of action. To evaluate this hypothesis, relative CBV changes before and after mannitol infusion were determined by collimated gamma counting across the biparietal diameter of the exposed skull in six dogs. Red blood cells were labelled with chromium-51. Cerebral blood volume (CBV), total blood volume (TBV), ICP, mean arterial pressure (MAP), central venous pressure (CVP), haematocrit and osmolality were serially measured after infusions of 10 μg.ml-1 of normal saline (control study) and of 20 per cent mannitol (mannitol study). The solutions were administered over a two-minute period; a 30-minute equilibration period intervened between the saline and mannitol infusions.We demonstrated that the mannitol infusion was associated with significant increases in relative CBV (25 per cent), ICP (7 mmHg), CVP (11 cm H2O). and TBV (50 per cent). MAP declined significantly (14 per cent) after mannitol infusion. The administration of saline, although associated with an increase in TBV (18 per cent), was not associated with any significant change in CBV, ICP, MAP or CVP.The increase in relative CBV persisted for 15 minutes after mannitol infusion, while the ICP returned to control within five minutes and continued to decrease. This study supports the fact that after rapid mannitol infusion, ICP begins to decrease only once the dehydrating effect has counteracted the increase in brain bulk caused by the increase in cerebral blood volume.RésuméLa baisse de la pression intracrânienne après une infusion de mannitol est généralement attribuée à un effet osmotique de deshydratation cérébrale. Récemment, une diminution du volume sanguin cérébral a été suggérée comme méchanisme d’action. Afin d’évaluer cette proposition, le volume sanguin cérébral relatif a été mesuré chez six chiens avant et aprés une infusion de mannitol, au moyen d’un récepteur de rayons gamma très précisement centré sur le diamètre bipariétal. Les globules rouges ont été marqués préalablement, au moyen de chrome-51. Le volume sanguin cérebral, le volume sanguin total, la pression intracréânienne, la pression artérielle moyenne, la pression veineuse centrale, l’ hématocrite et l’osmolalité ont été mesurés en série après des infusions de 10 ml.kg-1 de solution physiologique (contrôle) et de 10 ml-kg-1 de mannitol à 20pour cent. La durie d’infusion a été de deux minutes. Une période de 30 minutes d’équilibration a eu lieu entre les deux infusions. Léinfusion de mannitol a été immédiatement suivie d’une augmentation de 25 pour cent du volume sanguin cérébral, de 7 mmHg de la pression intracrânienne, de 11 cm H2O de la pression veineuse centrale et de 50 pour cent du volume sanguin total. La pression artérielle moyenne a baissé de manière significative (14 pour cent). Tous ces changements ont atteint leur maximum à la deuxième minute, et se sont graduellement corrigés dans I’heure après I’infusion de mannitol. L’infusion de solution physiologique, bien qu’associée à une augmentation du volume sanguin total de 18 pour cent, n’a entraîné aucun changement dans le volume sanguin cérébral, la pression intracrânienne, la pression artérielle moyenne ou la pression veineuse centrale. Après l’infusion de mannitol, l’augmentation du volume sanguin cérébral relatif a persisté de maniére significative pendant 15 minutes, alors que la pression intracrânienne retrouvait le niveau de contrôle en cinq minutes et continuait à baisser rapidement. Cette étude soutient le fait que, après une infusion rapide de mannitol, la pression intracrânienne ne commence à baisser que lorsque l’effet de deshydratation cérébrale a pu s’exercer et contrecarrer l’augmentation du volume cérébral total causée par I’augmentation transitoire du volume sanguin cérébral.