Combined OCT distance and FBG force sensing cannulation needle for retinal vein cannulation: in vivo animal validation.

PURPOSE: Retinal vein cannulation is an experimental procedure during which a clot-dissolving drug is injected into an obstructed retinal vein. However, due to the fragility and minute size of retinal veins, such procedure is considered too risky to perform manually. With the aid of surgical robots, key limiting factors such as: unwanted eye rotations, hand tremor and instrument immobilization can be tackled. However, local instrument anatomy distance and force estimation remain unresolved issues. A reliable, real-time local interaction estimation between instrument tip and the retina could be a solution. This paper reports on the development of a combined force and distance sensing cannulation needle, and its experimental validation during in vivo animal trials. METHODS: Two prototypes are reported, relying on force and distance measurements based on FBG and OCT A-scan fibres, respectively. Both instruments provide an 80 [Formula: see text] needle tip and have outer shaft diameters of 0.6 and 2.3 mm, respectively. RESULTS: Both prototypes were characterized and experimentally validated ex vivo. Then, paired with a previously developed surgical robot, in vivo experimental validation was performed. The first prototype successfully demonstrated the feasibility of using a combined force and distance sensing instrument in an in vivo setting. CONCLUSION: The results demonstrate the feasibility of deploying a combined sensing instrument in an in vivo setting. The performed study provides a foundation for further work on real-time local modelling of the surgical scene. This paper provides initial insights; however, additional processing remains necessary.

Intraoperatively diagnosed tracheal tear during a parathyroidec- tomy with previously undiagnosed tracheomalacia: a case report.

Tracheal rupture is a rare complication of endotracheal intubation and surgery of thyroid gland. We present a case of tracheal rupture diagnosed and repaired intraoperatively. A 76-year-old female patient with a recurrent parathyroid adenoma and cold thyroid nodule was scheduled for a bilateral exploration of the parathyroid glands associated to thyroid lobectomy. Induction of anesthesia was uncomplicated. Orotracheal intubation was easy and atraumatic using a 6.5mm EMG endotracheal tube (ETT) with low pressure cuff. Approximately 30 minutes after begining surgery, a tracheal tear was suspected by the anesthesiologist warned by his respiratory monitoring alarms (leakage in the ventilatory system). After confirming the diagnosis, a suture was performed and antibiotic coverage was administrated. The patient made a slight cervical subcutaneous emphysema and fully recovered after four weeks without any other complication. We review the litterature and discuss the risk factors of tracheal tear during thryroidectomy surgery and endotracheal intubation.

The changing face of malignant hyperthermia: less fulminant, more insidious..

Modern anaesthetic techniques have resulted in the clinical presentation of malignant hyperthermia to be more often indolent and/or insidious than truly fulminant, as previously known in the anaesthetic community. We present four recently referred cases to illustrate this point: one late-onset case, two patients with slowly progressive hypercapnia as the sole sign and a fourth patient with postoperative myalgias and elevated creatine kinase. We also discuss the reasons for the shift in typical clinical presentation. The more insidious character of malignant hyperthermia is most likely due to the lower triggering potency of modern volatile anaesthetics, the mitigating effects of several intravenous drugs (neuromuscular blocking agents, alpha 2 adrenergic receptor agonists, beta adrenergic blockade) or techniques (neuraxial anaesthesia) and the routine use of end-tidal CO2 monitoring leading to the early withdrawal of triggering drugs. Awareness among anaesthetists of this change in presentation is important since the clinical diagnosis is often more doubtful and, if corroborative evidence is not sought, the diagnosis may be delayed or missed altogether.

[The child with a known metabolic disease: anaesthetic management]. / L'enfant souffrant d'une maladie métabolique connue: stratégie anesthésique.

The anaesthetic management of a child with a known metabolic disease is always a challenge. It should be a multidisciplinary process based upon the experience of all medical specialists involved and on a thorough review of the information available in the literature and in specialized up to date websites. The authors propose a list of questions to be addressed when dealing with such a case and provide two clinical examples.

Paraplegia after combined general and epidural anesthesia: a case report.

Neurological complications after epidural anesthesia performed for abdominal surgery are uncommon, but of important consequence with significant morbidity. Paraplegia is very rare and may be a result of multiple factors. We report a case of elective colectomy under combined general and epidural anesthesia for a carcinoma. An epidural infusion was used for intra-operative and post-operative analgesia. During induction of anesthesia, the patient was asystolic for a few seconds and during the first postoperative day, a hypotensive episode was registered. He then developed a sensory-motor deficit in the legs. A spinal cord infarction at the level of T10 extending to T2 was diagnosed with magnetic resonance imaging. The association of hypotension as a cause of spinal cord infarction is discussed. The factors that may have contributed to paraplegia and preventive neuroprotective strategies are reviewed.

A comparison of intubation conditions and time-course of action with rocuronium and mivacurium for day case anaesthesia.

BACKGROUND AND OBJECTIVE: To compare intubation conditions and time-course of action of rocuronium and mivacurium for day case anaesthesia. METHODS: Fifty ASA I or II patients were enrolled. Anaesthesia was induced with propofol using a target controlled infusion system (target 6-8 microg mL(-1) ) and sufentanil (0.25 microg mL(-1). It was maintained with propofol (target 3.5-4.5 microg mL(-1) and 50% nitrous oxide in oxygen. Muscle relaxation was achieved with either mivacurium (0.15 mg kg(-1)) or rocuronium (0.3 mg kg(-1)). Neuromuscular transmission was monitored and recorded continuously by acceleromyography using a TOF-WATCH SX (Biometer; Denmark) with supramaximal train-of-four stimulation of the ulnar nerve. Tracheal intubation was carried out by an experienced anaesthetist blinded to the type of the muscle relaxant. Intubation conditions were evaluated according to a standard scheme (ease of laryngoscopy, position of vocal cords, airway reaction and limb movements). RESULTS: Intubation conditions were good or excellent for both mivacurium 0.15 mg kg(-1) (good = 8%; excellent = 92%) and rocuronium 0.3 mg kg(-1) (excellent = 100%). Times to maximum blockade and clinical duration were not different. CONCLUSIONS: There is no significant difference between mivacurium and rocuronium concerning the onset and the recovery of muscle relaxation. Rocuronium is an alternative to mivacurium for short procedures, without the risk of unexpected prolonged relaxation due to a possible defect in plasma cholinesterase.

Intravenous administration of tenoxicam 40 mg for post-operative analgesia: a double-blind, placebo-controlled multicentre study.

The analgesic efficacy of tenoxicam, a newer injectable non-steroidal anti-inflammatory drug, for post-operative analgesia after abdominal or orthopaedic surgery in ASA Grade I/II patients is reported. Two hundred and fifty-six patients received a single dose of tenoxicam 40 mg intravenous (i.v.) at the end of surgery and this was repeated 24 h later. These patients were compared, with respect to pain or adverse events, with 258 patients that received placebo. All patients were monitored for the next 72 h. Overall, tenoxicam provided reliable analgesia with comparable pain scores at rest, moving and coughing. The cumulative rescue PCA-morphine consumption was always lower in the tenoxicam treated patients and was most marked at 4 and 24 h after the second injection of tenoxicam. This effect was more pronounced after abdominal surgery. The intravenous administration of tenoxicam was associated with a low incidence of adverse events and a high tolerability.

Analgesic doses of intrathecal but not intravenous clonidine increase acetylcholine in cerebrospinal fluid in humans.

Epidural clonidine increases acetylcholine (ACh) concentrations in cerebrospinal fluid (CSF) in humans, and experiments in animals support a cholinergic link in spinal alpha2-adrenoceptor-mediated antinociception. The purpose of the present study was to evaluate whether intravenous (I.V.) clonidine is also able to increase CSF ACh in humans. Accordingly, we studied 20 patients scheduled for resection of an acoustic neuroma under general anesthesia. Anesthesia was induced with propofol and maintained with propofol and N2O. After induction, an intrathecal catheter was inserted at the L3-4 interspace. Patients were then assigned, in a random, blind manner to receive either a bolus of 1 microg/kg intrathecal (I.T.) clonidine and an I.V. infusion of saline (n = 10) or an I.V. infusion of 4 microg/kg clonidine given in 20 min and an I.T. injection of saline (n = 10). CSF samples for ACh and clonidine concentration determination were drawn immediately before I.T. injection (time -20), at the end of the I.V. injection (time 0), then every 10 min thereafter. CSF ACh concentrations were determined by high-pressure liquid chromatography and CSF clonidine by radioimmunoassay. There was no significant difference between the groups with respect to age, gender, weight, and ASA physical status. I.T. but not I.V. administration of clonidine increased the CSF ACh concentration. We conclude that I.V. administration of four times the dose of clonidine delivered spinally failed to induce a significant increase of ACh in the CSF. These observations indicate that the analgesic effects observed after I.V. clonidine administration are not mediated by a cholinergic mechanism at the spinal level.

Epidural clonidine used as the sole analgesic agent during and after abdominal surgery. A dose-response study.

BACKGROUND: Many studies have shown the beneficial effect of epidural clonidine in postoperative pain management. In these studies, the patients received local anesthetics, opioids, or both in combination with clonidine. Due to the interactive potentiation of those drugs, the importance of the intrinsic analgesic properties of the alpha 2-adrenoceptor agonist is difficult to establish. The authors investigated the analgesic potency of epidural clonidine when used as the sole analgesic agent during and after major abdominal surgery. METHODS: Fifty young adult patients undergoing intestinal surgery under general anesthesia with propofol were studied. At induction, the patients received epidurally either an initial dose of 2 micrograms/kg clonidine followed by an infusion of 0.5 microgram.kg-1.h-1 (group 1, n = 10) or 4 micrograms/kg followed by 1 microgram.kg-1.h-1 (group 2, n = 20) or 8 micrograms.kg-1.h-1 followed by an infusion of 2 micrograms.kg-1.h-1 (group 3, n = 20). During the operation, increases in arterial blood pressure or heart rate that did not respond to a propofol bolus (0.5 mg/kg) were treated with a bolus of intravenous lidocaine (1 mg/kg). Three successive injections were allowed. When baseline values were not restored, opioids were added and the patient was removed from the study. After operation, the clonidine infusions were maintained for 12 h. During this period and at every 30 min, sedation scores and visual analog scale values at rest and at cough were noted. In case of subjective scores up to 5 cm at rest or up to 8 cm at cough, the patients were given access to a patient-controlled analgesia device that delivered epidural bupivacaine. The end point of the study was reached once the patient activated the analgesic delivery button. RESULTS: During surgery, 60% of patients in group 1 compared with 33% of patients in group 2 and only 5% of patients in group 3 were removed from the study protocol because of inadequate anesthesia (P < 0.05). After operation, epidural clonidine provided complete analgesia lasting 30 +/- 21 min in group 1 compared with 251 +/- 237 min in group 2 or 369 +/- 256 min in group 3 (P < 0.05 for group 1 vs. groups 2 and 3 and group 2 vs. group 3). CONCLUSIONS: Epidural clonidine used as the sole analgesic agent provided dose-dependent control of the hemodynamic changes associated with surgical stimulation. It also produced dose-dependent postoperative analgesia without major side effects.

Epidural clonidine or sufentanil for intraoperative and postoperative analgesia.

This study contrasts the efficacy and side effects of epidural clonidine and sufentanil in the perioperative period. Using a randomized, prospective, double-blind study design, 40 patients undergoing abdominal surgery under propofol/nitrous oxide anesthesia were enrolled. Before anesthesia, an epidural catheter was inserted at the L1-L2 interspace. At induction of anesthesia, the patients received epidurally either clonidine (4 micrograms/kg in 10 mL) infused in 20 min followed by a 2-micrograms.kg-1.h-1 infusion (5 mL/h) during 12 h (Group 1) or sufentanil (0.5 microgram/kg in 10 mL) in 20 min followed by a 0.25-microgram.kg-1.h-1 infusion (5 mL/h) during 12 h (Group 2). Intraoperatively, increases in arterial blood pressure and heart rate not responding to propofol bolus (0.5 mg/kg) were treated with a bolus of intravenous (IV) sufentanil 0.035 microgram/kg. Postoperatively, IV sufentanil boluses (5 micrograms) were given through a patient-controlled analgesia (PCA) device. Postoperative analgesia was assessed by recording the IV PCA sufentanil requirements and the patients' visual analog scale (VAS) at 3, 6, 12, 18, 24, 36, and 48 h. Sedation analog scales and side effects were also recorded. Plasma clonidine and sufentanil concentrations were measured after 20 min and 6, 12, and 24 h. The number of reinjections of propofol (n = 1.6 +/- 1.6 in Group 1 vs 6.5 +/- 4.0 in Group 2) and of IV sufentanil (n = 0.6 +/- 0.8 in Group 1 vs 3.8 +/- 3.7 in Group 2) was significantly reduced (P < 0.001) in the epidural clonidine group. In the early postoperative period, pain scores and rescue analgesic requirements were very low in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of the adverse hemodynamic events occurring during "clonidine anesthesia": a prospective open trial of intraoperative intravenous clonidine.

STUDY OBJECTIVE: Determine the hemodynamic consequences of intraoperative clonidine during major abdominal surgery. DESIGN: Prospective open trial. SETTING: Teaching hospital. PATIENTS: 402 consecutive patients scheduled for major abdominal surgery. INTERVENTIONS: 350 consecutive patients received intravenous (IV) clonidine (loading dose of 4 micrograms/kg in 20 minutes at anesthesia induction, followed by a continuous infusion of 2 micrograms/kg/h until the end of surgery). Fifty-two additional patients served as controls. Anesthetic technique consisted of balanced anesthesia (isoflurane, fentanyl, atracurium). ECG, invasive arterial blood pressure (BP), expiratory PCO2 and pulse oximetry were continuously recorded. Hemodynamic events (HEs) were defined as moderate for a 20% reduction of the baseline systolic blood pressure (SBP) or a heart rate (HR) decreasing between 50 beats per minute (bpm) and 40 bpm. A 30% reduction of the baseline SBP or a HR below 40 bpm was considered an important HE. The rate and duration of these events were recorded from induction to recovery. HEs requiring a specific treatment were noted. Central venous pressure, volume of fluid infused, and urinary output were also recorded. MEASUREMENTS AND MAIN RESULTS: 21% of control patients and 31% of clonidine patients had no adverse HEs. A moderate reduction of the baseline BP was the most common episode in both groups. The incidence of the HEs (moderate and important) was similar in both groups but the duration HEs was significantly longer in the clonidine patients (p < 0.05). 40% of the control patients and 13% of the clonidine patients required specific management for their HEs (p < 0.05), the most common of which was hypotension without bradycardia. Neither coexisting pathology nor preoperative medications influenced the incidence of HEs. CONCLUSION: IV clonidine can be used routinely during anesthesia for major abdominal surgery.

[Craniostenosis and craniofacial dysmorphia]. / Craniosténoses et dysmorphies cranio-faciales.

The paper gives a brief historical survey of craniostenosis and the first operative approaches. The authors describe a classification of various types of cranio-facio-stenosis and facio-cranio-stenosis and present a detailed study of their experience in this area. Operative results are discussed in function of the selected surgical procedure, the immediate per- and post-operative complications and the short and long term morbidity. The authors present their current attitude for each dysmorphic type. They underline the heavy nature of this long-lasting and bleeding surgical procedure that concerns small children. They have recorded 31 incidents in relation with surgical procedure, 10 complications at short and long term, and 1 death. Such surgery requires an experienced and vigilant team, associating surgeons, anesthetists and intensive-care physicians.

Ketorolac tromethamine for postoperative analgesia in oral surgery.

Sixty patients were randomly allocated to receive placebo or i.v. ketorolac tromethamine 30 mg during the induction of anaesthesia for dental removal. Pain score (VAS), mouth opening and oedema were evaluated. Pain intensity was assessed by the patient using a visual analog scale 1, 2, 6 and 24 hrs after surgery. Mouth opening and oedema were evaluated at the same times by an observer not implicated in the study. In ketorolac group, pain relief was better at each considered time (VAS: p < 0.001). Oedema was also significantly lesser. There was no difference in mouth opening. No side effect was observed. These data suggest that ketorolac reduces post-oral surgery pain and oedema.