Catastrophic complication of an interscalene catheter for continuous peripheral nerve block analgesia.

We report a catastrophic postoperative complication of a prolonged interscalene block performed under general anaesthesia. The course of the anaesthetic was uneventful and the patient remained stable during his stay in the recovery area with the operative extremity paralysed and insensate. No further local anaesthetic was administered until later that day when the patient received 10 ml bupivacaine 0.25% through the catheter. Upon completion of the top-up dose, no change in the patient's status was noticed. The patient was next assessed 6.5 h later when he was found dead in his bed. A postmortem CT scan revealed the catheter to be sited intrathecally, presumably the result of dural sleeve penetration.

Parameters affecting pharyngeal response to genioglossus stimulation in sleep apnoea.

Chronic stimulation of the hypoglossus nerve may provide a new treatment modality for obstructive sleep apnoea (OSA). In previous studies we observed large differences in response to stimulation of the genioglossus (GG). We hypothesised that both individual patient characteristics and the area of the GG stimulated are responsible for these differences. In the present study, we compared the response to GG electrical stimulation at the anterior area (GGa-ES), which activates the whole GG and the posterior area (GGp-ES), which activates preferentially the longitudinal fibres. Studies were performed in 14 propofol-sedated OSA patients. The parameters evaluated included cephalometry, pressure-flow relationship and pharyngeal shape and compliance assessed by pharyngoscopy. Compared with GGa-ES, GGp-ES resulted in significantly larger decreases in the critical value of end-expiratory pressure (P(crit)) (from 3.8 ± 2.2 to 2.9 ± 3.3 and -2.0 ± 3.9 cmH(2)O, respectively (p<0.001)). Both tongue size and velopharyngeal shape (anteroposterior to lateral ratio) correlated significantly with the decrease in P(crit) during GGp-ES (R = 0.53 and -0.66, respectively; p<0.05). In the patients with the larger tongue size (n = 7), the decrease in P(crit) reached 8.0 ± 2.2 cmH(2)O during GGp-ES. We conclude that directing stimulation to longitudinal fibres of the GG improves the flow-mechanical effect. In addition, patients with large tongues and narrow pharynx tend to respond better to GGp-ES.

Gastro-Laryngeal Tube for endoscopic retrograde cholangiopancreatography: a preliminary report.

The Gastro-Laryngeal Tube is a modification of the Laryngeal Tube that provides a dedicated channel for the insertion of a gastroscope. In this study of 30 patients undergoing general anaesthesia for endoscopic retrograde cholangiopancreatography, we evaluated both the effectiveness of airway management with a Gastro Laryngeal Tube and the feasibility of performing it using the endoscopic channel. The Gastro Laryngeal Tube was inserted successfully in all patients, in 27 patients at the first attempt. The mean (SD) time to achieve an effective airway was 26 (6) s. Mean (SD) inspiratory and expiratory tidal volumes were 336 (57) ml and 312 (72) ml, respectively, and oropharyngeal leak pressure was 33.7 (2) cmH(2)O. These data suggest that the Gastro Laryngeal Tube is an effective and secure device for airway management and for use during performance of endoscopic retrograde cholangiopancreatography.

Collapsibility of the relaxed pharynx and risk of sleep apnoea.

The present study measured hypotonic pharyngeal collapsibility in subjects not known to have obstructive sleep apnoea (OSA), and assessed the variables that affect collapsibility and the relationship with OSA. The critical value of positive end-expiratory pressure (P(crit)) was measured under the hypotonic condition of anaesthesia in 227 subjects who underwent elective surgery. The risk of OSA in this population was estimated using the Berlin questionnaire. The mean P(crit) for all subjects was positive (above atmospheric), ranging from 0.69 (95% confidence interval (CI) -7.39-8.77) to 4.0 (CI -4.82-12.82) cmH(2)O for subjects with low and high prevalence of OSA, respectively. P(crit) < or = -5 cmH(2)O was only found in 3.1% of the study subjects. In the general population, P(crit) was similar in males and females and correlated positively with increasing age, while a correlation with neck circumference was found only in males. P(crit )accounted for only 12.25% of the variability in OSA risk score. In conclusion, subjects with high critical value of positive end-expiratory pressure are at an increased risk for developing obstructive sleep apnoea. However, the human pharynx is prone to collapse and occludes in most people in the absence of neuromuscular support. Therefore, in most subjects, the level of neuromuscular activity may ultimately determine the occurrence of sleep apnoea.

[The laryngeal tube]. / El tubo laríngeo.

The laryngeal tube (VBM Medizintechnic GmbH, Sulz, Germany) is a supraglottic device designed for airway management in spontaneous or positive-pressure ventilation during anesthesia or in cardiopulmonary resuscitation. Currently, the tube is available in 4 versions: the standard laryngeal tube, the disposable tube (LT-D), the dual-lumen tube (with a tube for suction) (LTS II), and the disposable LTS (LTS-D). The design of the tube has been modified several times. It is easy to insert and the airway seal is more effective than that of the laryngeal mask. The incidence of complications is similar for both devices, though use of the laryngeal tube requires more adjustments. The standard tube is somewhat less effective than the ProSeal laryngeal mask, though the new LTS II has been improved considerably. The laryngeal tube is effective as an aid to management of the difficult airway. We reviewed the literature indexed on MEDLINE through December 2006 using the search terms laryngeal tube, anesthesia, equipment, and airway.

Guidelines and algorithms for managing the difficult airway. / Guías y algoritmos para el manejo de la vía aérea difícil.

The difficult airway constitutes a continuous challenge for anesthesiologists. Guidelines and algorithms are key to preserving patient safety, by recommending specific plans and strategies that address predicted or unexpected difficult airway. However, there are currently no "gold standard" algorithms or universally accepted standards. The aim of this article is to present a synthesis of the recommendations of the main guidelines and difficult airway algorithms.

The capnography head-up tilt test for evaluation of chronic fatigue syndrome.

OBJECTIVES: To compare the hemodynamic and ventilatory responses to autonomic challenge evoked by upright tilt table testing in patients with chronic fatigue syndrome (CFS) to healthy individuals. METHODS: Thirty-two consecutive patients with CFS and 32 healthy volunteers were evaluated with the aid of the recently introduced capnography head-up tilt test (CHUTT). The main outcome measures were values of blood pressure (BP), heart rate (HR), respiratory rate (RR), and end-tidal pressure of co2 (ETPco2) recorded during recumbence and tilt. In addition, the end points of vasodepressor and cardioinhibitory reactions, hyperventilation (defined by ETPco2 <25 mm Hg) and the postural tachycardia syndrome, were recorded. RESULTS: The BP, HR, RR, and ETPco2 recorded during recumbence were similar in both groups. During tilt, patients with CFS developed significantly lower systolic BP, diastolic BP, and ETPco2, and a significant rise in HR and RR (P<.01). In CFS patients, the postural tachycardia syndrome occurred in 44%, vasodepressor reaction in 41%, cardioinhibitory reaction in 13%, and hyperventilation in 31% of cases. One or more end points of the CHUTT were reached in 78% of patients with CFS but in none of the controls (P<.0001). CONCLUSIONS: In most patients with CFS, a spectrum of abnormal homeostatic reactions is diagnosed with the aid of the CHUTT. Data provided by the CHUTT may reinforce the clinical diagnosis by adding objective and unbiased criteria to the subjective assessment of CFS.

Hemodynamic instability in chronic fatigue syndrome: indices and diagnostic significance.

OBJECTIVES: To evaluate the cardiovascular response to postural challenge in patients with chronic fatigue syndrome (CFS) and to determine whether the degree of instability of the cardiovascular response may aid in diagnosing CFS. METHODS: Patients with CFS (n = 25) and their age- and gender-matched healthy controls (n = 37), patients with fibromyalgia (n = 30), generalized anxiety disorder (n = 15), and essential hypertension (n = 20) were evaluated with the aid of a standardized tilt test. The blood pressure (BP) and heart rate (HR) were recorded during 10 minutes of recumbence and 30 minutes of head-up tilt. We designated BP changes as the differences between successive BP values and the last recumbent BP. The average and standard deviation (SD) were calculated. Time curves of BP differences were loaded into a computerized image analyzer, and their outline ratios and fractal dimensions were measured. HR changes were determined similarly. The average and SD of the parameters were calculated, and intergroup comparisons were performed. RESULTS: On multivariate analysis, the independent predictors of CFS patients versus healthy controls were the fractal dimension of absolute values of the systolic BP changes (SYST-FD.abs), the standard deviation of the current values of the systolic BP changes (SYST-SD.cur), and the standard deviation of the current values of the heart rate changes (HR-SD.cur). The following equation was deduced to calculate the hemodynamic instability score (HIS) in the individual patient: HIS = 64.3303 + (SYST-FD.abs x -68.0135) + (SYST-SD.cur x 111.3726) + (HR-SD.cur x 60.4164). The best cutoff differentiating CFS from the healthy controls was -0.98. HIS values >-0.98 were associated with CFS (sensitivity 97%, specificity 97%). The HIS differed significantly between CFS and other groups (P <.0001) except for generalized anxiety disorder. Group averages (SD) of HIS were CFS = +3.72 (5.02), healthy = -4.62 (2.26), fibromyalgia = -3.27 (2.63), hypertension = -5.53 (2.24), and generalized anxiety disorder = +1.08 (5.2). CONCLUSION: The HIS adds objective criteria confirming the diagnosis of CFS.

The capnography-tilt test for the diagnosis of hyperventilation syncope.

We describe the capnography tilt test (CTT) for the diagnosis of hyperventilation syncope. The CTT is a 10-min supine, 30-min head-up tilt test with simultaneous monitoring of end-tidal PCO2 (ETPCO2). Hyperventilation (HV) was defined as ETPCO2 < or = 25 mmHg. Hyperventilation syncope (HV syncope) was defined as loss of consciousness with ETPCO2 < or = 25 mmHg and no significant drop in blood pressure. Four groups of patients had the CTT: group I (n = 14), patients presenting with syncope who during a prior tilt test had lost consciousness without concomitant fall in blood pressure; group II (n = 50), syncope, primary evaluation, no prior tilt test done; group III (n = 20), generalized anxiety disorder, no syncope; group IV (n = 80), arterial hypertension, no syncope. Hyperventilation was found in 11/14 patients in group I, 5/50 in group II, 7/20 in group III, and none in group IV; HV syncope was diagnosed in seven patients, all in group I. None of the parameters measured in the evaluation, including ETPCO2, predicted HV syncope on tilting. The mechanisms of resting HV and HV during tilt are not well understood. We confirm the existence of HV syncope. The tilt test should probably be used to screen patients presenting with syncope, with the CTT reserved for patients who lose consciousness during the tilt test without an associated fall in blood pressure, as HV is not always clinically obvious.

In-field validation of automatic blood pressure measuring devices.

The method for rapid evaluation of automatic blood pressure (BP) measurement devices (READ) is based on numerous BP measurements at rest and during a standardised postural challenge in a small number of subjects with a wide range of BPs. The present study proposes additional parameters of the READ for in-field validation of automatic BP measurement devices. BP measurements were done in supine position for 10 min followed by head-up tilt for 30 min and again supine for 10 min. BPs were determined simultaneously by automatic (AU) and mercury sphygmomanometric (MS) measurements on the same arm. The BP differences DeltaBP:AU-MS were calculated. Three units of the Colin BP-8800 and the Datex-Engstrom Cardiocaptrade mark II were evaluated. Based on DeltaBP(AU-MS), the grade of accuracy, aberration patterns and correlates of accuracy were assessed for each unit. Per unit, an average of 121 measurements were done, every BP category being met in >/=20 MS measurements. In general, the AU systolic BP values were higher than MS systolic BP values (mean systolic DeltaBP = 1.26 +/- 17.1 mm Hg) and AU diastolic BP values were lower than MS diastolic BP values (mean diastolic DeltaBP = -12.31 +/- 7.8 mm Hg). All units classified into category D of the British Hypertension Society grading system and exhibited inconsistent aberration patterns, making design of correction formulas impractical. Inaccuracy of the instruments was independent on mode of measurement, posture, magnitude of the BP and heart rate, early or late measurements from beginning of the head-up tilt test, and prolonged use of the unit. The READ permitted to identify rapidly the degree of accuracy of automatic BP measuring devices. Identification of the aberration pattern of an instrument could be the basis for calculating equations for correction of the measured BP. Further studies will show which parameters of the READ may expose specific defects of the instruments. Journal of Human Hypertension (2000) 14, 37-42.

Accuracy of the OMRON M4 automatic blood pressure measuring device.

Despite widespread use of the automatic blood pressure (BP) measuring device OMRON M4, there is little formal validation on its accuracy. A study was conducted to assess the accuracy of the OMRON M4 compared with the true indirect BP measured by mercury sphygmomanometer (MS). A rapid method for the evaluation of automatic blood pressure measurement devices (READ) was applied for this study. The READ is based on numerous BP measurements at rest and during a standardised postural challenge in a small number of subjects who exhibit a wide range of BPs. Blood pressure measurements were done in supine position for 10 min followed by head-up tilt for 30 min and again supine for 10 min. The automatic device (AU) and the MS were connected to one arm-cuff by means of a T connector. A stethoscope with dual sets of ear-pieces was used for duplicate MS measurements (MS1 and MS2). The MS1, MS2 and AU measurements were taken simultaneously in a blinded manner. Three units of the automatic instrument were evaluated. An average of 111 measurements per unit were performed, every BP category being present in >/=15 MS measurements. The differences between MS1 and MS2 measurements (DeltaBP: MS1-MS2) were utilized to assess the consistency of true indirect BP and the differences between AU and MS measurements (DeltaBP:AU-MS2) were utilized to assess the accuracy of the AU. The following characteristics of the OMRON M4 were assessed: (1) grade of accuracy, (2) aberration pattern, (3) consistency of the aberration-pattern, and (4) correlation between levels of BP and DeltaBP: AU-MS. For MS paired readings, 92-100% of systolic and 99-100% of diastolic readings fell within 5 mm Hg difference range, that is consistent with a British Hypertension Society grade A of both. For AU compared to MS2, 29-64% of systolic and 73-94% of diastolic readings fell within 5 mm Hg and 49-86% of systolic and 86-99% of diastolic readings fell within 10 mm Hg and the devices qualified C, D and C, respectively. All devices exhibited irregular and inconsistent aberration patterns, making the design of correction formulas impractical. In conclusion, the OMRON M4 device did not meet the requirements of the British Hypertension Society and, therefore, cannot be recommended for clinical use.

Rapid estimation of the accuracy of automatic blood pressure measuring devices (READ).

We propose a rapid method for the evaluation of automatic blood pressure measurement devices (READ) in response to the claim to simplify the validation of those devices. The READ is based on numerous blood pressure (BP) measurements at rest and during a standardised postural challenge in a small number of subjects who exhibit a wide range of BPs. Automatic (AU) and mercury sphygmomanometric (MS) brachial BP were measured simultaneously in a blinded manner. An average of 30 measurements per patient were done in 10-min while in a supine position, followed by 30 min in head-up tilt and again supine for 10 min. Two Collin-8800 automated oscillometric devices were tested with the aid of the READ in 15 adults. The consistency of the MS standard was demonstrated by duplicate MS measurements showing minimal inter-observer differences consistent with class A of the British Hypertension Society (BHS) grading system. AU-to-MS differences of 447 measurements were mean systolic deltaBP = 1.1 +/- 11.4 mm Hg and mean diastolic deltaBP = -13.36 +/- 8.9 mm Hg, classifying into category D of the BHS. Both tested instruments, each subject, each phase of the tilt test (supine I, tilt, supine II) and each mode of measurement (at 5-min intervals or continuously) equally qualified as 'D'. We conclude that the READ permitted us to identify quickly and at low expense a grossly inaccurate automatic BP measuring device. Further studies will show whether the READ can be efficient as a pre-validation test, post-validation test, and for assessment of ambulatory BP measuring devices.

The Haemodynamic Instability Score (HIS) for assessment of cardiovascular reactivity in hypertensive and normotensive patients.

The normal response to postural challenge is characterised by maintenance of relatively stable blood pressure (BP) and heart rate (HR) after 30 sec to 30 min of head-up tilt. The objective of the present study was to determine the degree of instability of cardiovascular responses to postural challenge in normotensive and hypertensive subjects. In the initial phase of the study, two groups of age and sex-matched subjects were assessed: essential hypertension (n = 20) and healthy (n = 37). The BP and HR were recorded at 5-min intervals during the course of the 10-min supine-30-min head-up tilt test (HUTT). We categorised 'BP-change' as the difference between individual BP measurements during HUTT and the last recumbent BP value, divided by latter value. The average and standard deviation (SD) of the recorded BP changes were calculated, and BP changes were plotted along a time curve. A computerised image analyser then calculated the outline ratio (OR) and fractal dimension (FD) values for each of the curves. An identical process evaluated measurements for HR-changes. BP- and HR-changes were then converted into absolute numbers, and the average, SD, OR, and FD were calculated. A multivariate analysis was conducted, evaluating independent predictors of hypertension. Finally, an equation for the calculation of 'haemodynamic instability score' (HIS) was deduced and a cut-off between HIS of hypertensive and normotensive subjects was established. Independent predictors of the cardiovascular response to postural challenge of hypertensives (Group I) vs healthy (Group II) were: a.DIAST-FD, a.HR-AVG, a.HR-SD, a.HR-FD, DIAS-SD and HR-SD and HR-SD. Based on these five predictors, a linear discriminant score was computed and called the Haemodynamic Instability Score (HIS): HIS = 59.4 + (-16.6*a.DIAST-FD) + (-29.0*a.HR-AVG) + (-82.4*a.HR-SD) + (-30.1*a.HR-FD) + (-57.9*DIAS-SD) + (73.4*HR-SD) The HIS values in Group I (hypertensives) were: avg = 3.348, SD = 2.863, and 95% CI for mean = 2.008, 4.688. The HIS values in Group II (healthy) were: avg = -3.394, SD = 2.435, 95% CI for mean = -4.206, -2.582. Values of the HIS > -2.09 were generally observed in hypertensives (sensitivity 95%) and values < or = -2.09 were usually seen in the healthy (specificity 81.1%). The HIS was cross-validated in an additional group of hypertensive patients (n = 73). In the latter group, the HIS values were: avg = -0.456, SD = 4.403, 95% CI for mean = -1.506, 0.593 and 71.4% sensitivity at the proposed cut-off point. In conclusion, the HIS confers numerical expression to the degree of lability of BP and HR during postural challenge. Based on this score, a distinction between the cardiovascular reactivity of hypertensives vs normotensives is drawn. Possible applications of HIS are discussed.

Vancomycin sequestration during cardiopulmonary bypass surgery.

OBJECTIVE: The present study was designed to analyze vancomycin disposition in adult patients undergoing coronary bypass grafting during and following cardiopulmonary bypass (CPB). METHODS: Coronary bypass surgery was performed on 11 adults with a mean age (SD) of 62.9 (9.0) years old, who received a mean (SD) vancomycin prophylactic dose of 12.7 (1.0) mg/kg in a mean period of 41 (0.7) min. Using a two-compartment open model for pharmacokinetic analysis, the following parameters were obtained: alpha half-life, minutes (t(1/2alpha)); beta half-life, hours (t(1/2beta)); apparent volume of distribution, (V(d) l/kg); volume of the central compartment, (V(c) l/kg), constant between the "central to the peripheral" compartment, (k(12)); constant between the "peripheral to the central" compartment, (k(21)); total area under the concentration-time curve, (AUC mg/lxh) and a vancomycin clearance, (Cl(van) ml/min), respectively. RESULTS: The mean (SD) calculated pharmacokinetic parameters were: t(1/2alpha)17.6 (6) min, t(1/2beta) 8.4 (3.8) h, V(d) 0.803 (0.259) l/kg, V(c) 0.270 (0.162) l/kg, k(12) 0.03 (0.015), k(21) 0.012 (0.012), total AUC 10377.2 (3687.6) mg/lxh. The mean (SD) vancomycin clearance by the CPB machine was 9.51 (2.66) l/h, and the mean (SD) total vancomycin sequestrated by CPB was 331.7 (84) mg. A significant difference (6.3%; p = 0.001) was measured between the mean measured AUC during CPB (1088.1 +/- 253.9) and the same calculated parameter (1160.2 +/- 282). Five minutes after starting CPB, a decrease in vancomycin level was detected; this difference was found to be nearly 11% in absolute values. CONCLUSIONS: This confirmatory study demonstrated that the vancomycin blood concentrations obtained during the study allow recommending a safety prophylactic dose of 12mg/kg in adults who undergo open-heart surgery under CPB conditions. Sequestration of vancomycin by the oxygenator or/and tubing system of the CPB machine had occurred and had been measured in this study.

Effects of peritonsillar infiltration on post-tonsillectomy pain. A double-blind study.

The concept that local infiltration of the operative area with a local anesthetic when using general anesthesia could alleviate postoperative pain is well known. We tested this concept on 129 patients scheduled for elective tonsillectomy. The patients were investigated in a double-blind, randomized study, and the operation was carried out via the standard technique of infiltrating the peritonsillar area preoperatively. The results indicated that preincisional infiltration of the tonsils with bupivacaine hydrochloride markedly decreased the intensity of pain following tonsillectomy, well beyond the immediate postoperative period.

Pneumomediastinum due to Venturi jet ventilation used during microlaryngeal surgery in a previously neck-irradiated patient.

Serious complications secondary to Venturi jet ventilation used during microlaryngoscopy are rare, but when they occur, they may pose a life-threatening emergency. We report the case of a 45-year-old woman, previously treated with 70 Gy of irradiation for a T1 laryngeal carcinoma, who developed pneumomediastinum and subcutaneous emphysema after the use of Venturi jet ventilation. Keeping in mind the histologic changes to the irradiated structures, we suggest more caution when using Venturi jet ventilation in patients who have recently undergone neck irradiation therapy.

Inferior turbinectomy versus submucosal diathermy for inferior turbinate hypertrophy.

In order to compare and evaluate bilateral inferior turbinectomy (BIT) and submucosal diathermy (SMD), we retrospectively examined these two well-known techniques for treatment of nasal obstruction due to bilateral congestion of the inferior turbinates. One hundred patients with bilateral nasal obstruction were divided into 4 groups according to their nasal airflow patency. Forty-nine patients underwent BIT, and 51 patients underwent SMD. All 100 patients were followed for 2 months after surgery. Patients with difficult postoperative courses were followed up to 1 year after surgery, in order to decide on the necessity of operative revision. Postoperative improvement in nasal breathing after BIT was reported for 96% of patients 2 weeks after surgery, and for 88% 2 months after surgery. Only 1 BIT patient had to undergo revision operation. Diathermy showed good results in 78% of cases 2 weeks after surgery. The efficacy of the procedure was reduced to 76% 2 months after surgery. Twenty percent of SMD patients were advised to undergo operative revision. Postoperative bleeding occurred in 20% of BIT patients and in only 4% of SMD patients. We found that the extent of postoperative improvement does not depend on preoperative conditions; therefore, it is impossible to predict the extent of postoperative improvement on the basis of the results of preoperative assessment. Both procedures can be performed under local anesthesia, are relatively safe and effective, and do not need expensive instrumentation that may not be available in many medical centers.

Replacing the combitube by an endotracheal tube using a fibre-optic bronchoscope during spontaneous ventilation.

We present a case of microlaryngoscopy in a patient with an unexpectedly difficult airway. The airway was managed by using an oesophageal-tracheal Combitube (Kendall-Sheridan, Argyle, NY) (ETC) and a fibre-optic bronchoscope (Pentax-Japan-5 mm).

Failure to control the airway in a patient with Hunter's syndrome.

Hunter's syndrome is due to recessively inherited mucopolysaccharide storage diseases. The anaesthetic complications in this syndrome are related to the organs involved in the disease, but pertain especially to upper airway obstruction problems. We report a patient with Hunter's syndrome who, while under general anaesthesia for a simple procedure (the introduction of bilateral grommets), suffered a fatal outcome.