bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy-efficient routing protocol based on tree link topology in wireless sensor networks
Authors: Ang Li
Published: January 2019

Wireless sensor networks have been widely used in target monitoring application. It is often assumed in a typical target coverage algorithm that the environment is known, and each target is covered by only one node. However, these algorithms are not scalable. In fact, one target may need to be covered by more than one node, which is the K-coverage problem. Aiming at the application of target monitoring in wireless sensor network, a K-coverage model— kernal matrix based genetic algorithm (KMGA) based on the genetic algorithm—is proposed. The KMGA model ensures that each target is covered by multiple sensors simultaneously. First, multiple Covers are generated as much as possible through genetic algorithm, and then, while coverage requirements are ensured, coverage between Covers is switched based on remaining energies of nodes so as to extend the network life. Experimental data show that the proposed KMGA model can effectively extend the network lifetime and ensure coverage rate.
Neck and Shoulder Motor Function following Neck Dissection: A Comparison with Healthy Control Subjects
Authors: Gane Elise M. , McPhail Steven M. , Hatton Anna L. , Panizza Benedict J. , O'Leary Shaun P.
Published: January 2019

Objective

To compare the neck and shoulder motor function of patients following neck dissection, including comparison with a group of healthy volunteers.

Study Design

Cross‐sectional study.

Setting

Two tertiary hospitals in Brisbane, Australia.

Subjects and Methods

Participants included patients 0.5 to 5 years after unilateral nerve‐sparing neck dissection and healthy control subjects. Demographic and clinical information was collected with cervical and shoulder motor function measures (scapular resting position, active range of motion, and isometric muscle strength). Differences between groups were examined via regression analyses that included statistical adjustment for the potential effect of age, sex, body mass index, and other disease‐related variables.

Results

The 57 patients (68%, men; median age, 62 years) were typically older than the 34 healthy controls (47%, men; median age, 46 years). There were no differences between types of nerve‐preserving neck dissection for any of the motor function measures. When adjusted for age, sex, and body mass index, healthy volunteers (vs patients) had significantly greater cervical range (eg, extension coefficient [95% CI]: 11.04° [4.41°‐17.67°]), greater affected shoulder range (eg, abduction: 16.64° [1.19°‐31.36°]), and greater isometric strength of the cervical flexors (eg, men: 4.24 kgf [1.56‐6.93]) and shoulder flexors (eg, men: 8.00 kgf [1.62‐14.38]).

Conclusions

Strength and flexibility of the neck and shoulder are impaired following neck dissection in comparison with healthy controls. Clinicians and researchers are encouraged to consider the neck—and the neck dissection as a whole—as a source of motor impairment for these patients and not just the status of the accessory nerve.
Airway Closure Delay: The Predominant Pathophysiology in Reflux‐Associated Dysphagia
Authors: Kendall Katherine A.
Published: January 2019

Objective

Reflux disease is common in patients with oropharyngeal dysphagia, but the impact of reflux on oropharyngeal swallowing physiology is not known. This study uses objective measures of swallowing function from modified barium swallow studies to describe the pathophysiology of dysphagia in a group of patients whose only associated condition is reflux.

Study Design

Retrospective chart review.

Setting

Tertiary care voice and swallowing clinic.

Subjects and Methods

The Swallowing Database at the University of Utah was queried for patients with a diagnosis of reflux without additional conditions known to affect swallowing function. Pharyngeal transit time (TPT), distance of hyoid elevation (Hmax), maximum opening size of the upper esophageal sphincter (UESmax), area of pharynx at maximum constriction (PAmax), airway closure timing relative to the arrival of the bolus at the UES, and penetration/aspiration (Pen/Asp) score were assessed.

Results

Of the 122 patients who met inclusion criteria for the study, 42% had normal pharyngeal swallowing function, 57% had at least 1 abnormal swallowing measure, and 47.5% demonstrated a delay in airway closure relative to arrival of the bolus at the UES on at least 1 swallow. The incidence of prolonged TPT, diminished Hmax, poor UESmax, and enlarged PAmax were 2.5%, 8%, 4%, and 11.5%, respectively. Sixty percent with a delay in airway closure had a normal Pen/Asp score.

Conclusion

A delay in airway closure relative to the arrival of the bolus at the UES is the most common abnormality of swallowing function found in patients with reflux‐associated dysphagia but may not be identified using the Pen/Asp score.
Relative Preservation of Superior Semicircular Canal Architecture in CHARGE Syndrome
Authors: Tawfik Kareem O. , Leader Brittany A. , Walters Zoe A. , Choo Daniel I.
Published: January 2019

Objectives

(1) Describe common patterns of semicircular canal (SCC) anomalies in CHARGE syndrome (CS) and (2) recognize that in CS, the architecture of the superior SCC may be relatively preserved.

Study Design

This is a retrospective review of temporal bone imaging studies.

Setting

Quaternary care center.

Subjects and Methods

A sample of 37 patients with CS. All subjects met clinical diagnostic criteria for CS. The presence/absence of anomalies of the middle ear, mastoid, temporal bone venous anatomy, inner ear, and internal auditory canal was recorded. Anomalies of each SCC were considered separately and by severity (normal, dysplasia, aplasia).

Results

Thirty‐seven subjects (74 temporal bones) were reviewed. Thirty‐four (92.0%) patients demonstrated bilateral SCC anomalies. Three (8.0%) had normal SCCs. In patients with SCC anomalies, all canals demonstrated bilateral abnormalities. Thirty‐two (86.5%) patients had bilateral horizontal SCC aplasia. These 32 patients also demonstrated posterior SCC aplasia in at least 1 ear. Of 74 temporal bones, 37 (50.0%) had superior SCC dysplasia. All dysplastic superior SCCs showed preservation of the anterior limb. Complete superior SCC aplasia was found in 28 (37.8%) temporal bones.

Conclusion

SCC anomalies occur with high frequency in CS. Complete absence of the horizontal and posterior canals is typical and usually bilateral. By contrast, the superior SCC often demonstrates relative preservation of the anterior limb.
Association of Respiratory Mechanic Instability and Respiratory Parameters among Adults with Obstructive Sleep Apnea
Authors: Choi Ji Ho , Lee Bora , Hwang Se‐Hwan
Published: January 2019

Objectives

Respiratory mechanic instability (RMI) is derived from analysis of paradoxical thoracoabdominal movements during airway obstruction. This study aimed to evaluate RMI parameters in obstructive sleep apnea (OSA) and the correlation between RMI parameters and other parameters in polysomnography.

Study Design

Retrospective review.

Setting

A university hospital.

Methods

A retrospective chart review was performed, and data from 189 adult patients who underwent an in‐laboratory sleep study and were seen in our clinic during the past 8 months. The RMI parameters were measured from thoracoabdominal bands during polysomnography.

Results

Subjects were divided into 2 groups: control (n = 67, apnea‐hypopnea index [AHI] <5) and OSA (n = 122, AHI ≥5). The OSA group was divided into 3 subgroups according to AHI: mild, 5 ≤ AHI < 15; moderate, 15 ≤ AHI < 30; severe, AHI ≥30. As AHI increased, all RMI parameters showed a significant rising pattern and difference between control and subgroups. Arousal index, lowest oxygen saturation, and oxygen desaturation index ≥3% were significantly correlated with all RMI parameters. Based on cutoff values, areas under the curves of the RMI index for predicting mild, moderate, and severe OSA were >0.85.

Conclusion

All RMI parameters were well related to respiratory parameters of polysomnography, such as arousal index, lowest oxygen saturation, and oxygen desaturation index ≥3%. The areas under the curves of all RMI parameters for predicting OSA and subgroups showed significant diagnostic performance. These parameters may be useful to identify OSA cases from control.
Adverse Reactions due to Leucocyte and Platelet Antibodies
Authors: Bashir Helen
Published: January 2019

Each blood transfusion exposes the recipient to the hazards of immunisation to histocompatibility antigens as well as white cell and platelet antigens. As the number of transfusions received by a patient increases so too does the likelihood of the development of antibodies which may by their multispecific character effectively prevent lifesaving therapy in the future. Special steps can and should be taken to minimise the risks of immunisation in the group of patients who will be dependent on long term transfusion therapy. An extension of knowledge about the antigenic systems of leucocytes and platelets, including HLA, and the introduction of more specific tests for the detection of antibodies directed against them should assist in the provision of more appropriately matched blood components.
Massive Blood Transfusion
Authors: Benson Ronald E. , Isbister James P.
Published: January 2019

Massive blood transfusion is associated with a wide range of adverse effects, some of which are understood, but controversy surrounds the effects of massive blood loss and transfusion on haemostasis and oxygen transport. Until we have a better understanding of the underlying pathophysiology and while storage of blood remains imperfect, there is a good case for the empirical use of super-fresh blood in this clinical setting. A practical approach to the exsanguinated patient is presented.
Quality Control and Transfusion Reactions
Authors: Beal R. W.
Published: January 2019

The relative safety of homologous blood transfusion is in large part due to constant surveillance by blood bankers and clinicians. Quality control of blood supply and transfusion includes collection, documentation, storage, serological testing, administration and follow-up. The provision of serologically compatible blood requires meticulous monitoring of grouping, screening and crossmatching techniques. A hospital transfusion committee should be an integral part of any quality control programme to ensure effective communication between clinical, laboratory and administrative staff
Thrombus Formation on Cannulae
Authors: Hecker J. F.
Published: January 2019

Seven types of cannulae were inserted into the cephalic vein of sheep which were killed after 1, 3 or 9 days so that the mass of thrombus associated with each cannula could be measured. Statistical analysis indicated that there was a statistically significant difference of greater than 2-fold between types of cannulae in the amount of thrombus. Differences between the 3 periods were not significant.
Sympathomimetic Amines
Authors: Runciman W. B.
Published: January 2019

The autonomic nervous system may play an important role in tissue autoregulation as the neurohumoral transmission process has been shown to constitute the final common pathway by which the effects of many physiological and pharmacological substances are mediated. The effects of the administration of a sympathomimetic amine cannot be accurately predicted in a subject. Choice of which sympathomimetic amine to use should be determined on the basis of data obtained in relevant clinical circumstances, but the dose should always be titrated against the effect in each individual.

It is interesting that adrenaline, “the original autonomic drug” with its “venerable history”,56 is still a first line drug in many of the situations for which it was being prescribed in 1907. It is the drug of first choice in anaphylactic reactions and for severe allergic bronchospasm, and is widely used as a vasoconstrictor in surgery and with local anaesthetic agents. Adrenaline in “physiological” doses is a satisfactory and cheap alternative to other available drugs for use in septic shock and in emergence from cardiopulmonary bypass.
Repeated Doses of Suxamethonium
Authors: Cass N. M. , Brace G. R.
Published: January 2019

Repeated sub-apnoeic doses of suxamethonium produce increased neuromuscular block in a hand muscle, measured by integrated electromyogram. The response to the initial dose varies widely between patients. More than 50% of patients showed evidence of non-depolarising block after one dose of suxamethonium. There was a variation between the response of the hand muscle and respiratory muscles.
Anaesthetic Complications Requiring Intensive Care: A five year review
Authors: Barnes P. J. , Havill J. H.
Published: January 2019

In a five-year period 110 patients were admitted to the intensive therapy unit (ITU) as a result of ‘a complication related to anaesthesia’. The nature of the complication and its outcome are analysed. The most common reasons for admission were cardiopulmonary arrest (32), failure to reverse after muscle relaxants (25), airway problems, and various drug reactions. Twelve deaths occurred in the 110 cases studied.
A Comparison of the Robertshaw and Carlens-Type Double-Lumen Tubes for Thoracic Anaesthesia
Authors: Rigg Douglas
Published: January 2019

A comparison was made between the Robertshaw and the Carlens or White tubes for ease of insertion and success of positioning in patients about to undergo thoracotomy. The Carlens and the left Robertshaw tubes performed equally but the 35 Carlens was successfully used in three patients in whom the small Robertshaw had proven to be unsuitable. The White tube, however, was inferior to the right Robertshaw because it was found impossible to seal the bronchial cuff satisfactorily in many of the cases in which it was used.
Preoperative Cimetidine — Effects on Gastric Fluid
Authors: Barnes P. J. , Havill J. H.
Published: January 2019

A double blind study of 44 patients (24 placebo, 20 cimetidine) was undertaken to determine the effect of cimetidine on the pH and volume of gastric fluid during anaesthesia. The pH was significantly higher on cimetidine-treated patients than placebo-treated patients at 0, 15, 30 and 45 minutes following intubation. At induction of anaesthesia, mean pH on cimetidine was 4.5 and on placebo mean pH was 2.0. Approximately 70% of patients on cimetidine and 20% on placebo recorded a pH above 2.5 during anaesthesia. The reason for a pH recording of less than 2.5 in seven patients on cimetidine could not be ascertained.

Mean volume of gastric aspirate was slightly lower in the cimetidine group at 0, 15, 30 and 45 minutes, but the differences were not significant.
A Comparison of Hyper- and Isobaric Solutions of Bupivacaine for Subarachnoid Block
Authors: Phelan Dermot M. , MacEvilly Myles
Published: January 2019

The comparative efficacy of two solutions of bupivacaine, 0.5% plain (isobaric — specific gravity 1.010), and 0.4% bupivacaine (hyperbaric — specific gravity 1.027) in 4% dextrose, for spinal anaesthesia was studied in 67 patients. Both solutions were clinically satisfactory (94% completely successful neural blockade). Hyperbaric bupivacaine blocks a greater number of spinal segments (p < 0.01), causes a more rapid fall in blood pressure (p < 0.05), and is more predictable in effect with regard to the number of segments blocked and to the lateralisation of the block. The duration of perioperative analgesia with the hyperbaric preparation is, however, shorter — 3.8 hours as opposed to 5.8 hours (p < 0.01) — but this was likely to be due to the smaller total dosage of bupivacaine used in the hyperbaric group. It is concluded that either solution may be used satisfactorily in clinical practice. The isobaric solution, however, despite its ready availability, is less satisfactory than the hyperbaric because its effect with regard to the extent of blockade is less predictable.
Procainamide Infusion and Acute Atrial Fibrillation
Authors: Fulham M. J. , Cookson W. O. C. , Sher M.
Published: January 2019

We report the use of intravenous procainamide infusion in the treatment of fifteen patients with acute atrial fibrillation. Procainamide was infused at 50 mg/min to a maximum of 20 mg/kg, with blood pressure and electrocardiographic monitoring. Ten patients responded, with a mean dose of 8.7 (standard deviation 4.3) mg/kg, four of these reverting to sinus rhythm after a low dose of less than 5.0 mg/kg. Hypotension was a common concomitant and was seen in four cases, but required termination of the infusion only in a patient with cardiomyopathy. An increase in ventricular rate or conversion to atrial flutter was not seen. Intravenous infusion of procainamide is a safe and moderately effective method of cardioversion in acute atrial fibrillation.
Failure of IV Atropine to Abolish Nasal Irritation Caused by Chlormethiazole Infusion in Elderly Patients Undergoing Spinal Anaesthesia
Authors: Seow L. T. , Mather L. E. , Cousins M. J.
Published: January 2019

The efficacy of intravenous atropine in abolishing the nasal irritation of chlormethiazole was assessed. Forty elderly patients undergoing transurethral resection of prostate under spinal anaesthesia were studied. One ml of either atropine sulphate (0.6 mg) or normal saline was administered intravenously in a double-blind fashion 10 minutes prior to infusion of 0.8% chlormethiazole edisylate. A loading infusion of 5 ml.min–1 of the chlormethiazole solution was followed by a variable rate of infusion in order to maintain a predetermined state of sedation — i.e. where the patient lapsed into sleep but was easily awakened to obey commands. Sneezing was the commonest side-effect occurring in 45% and 70% of patients in atropine and saline groups respectively. This was not effectively abolished by IV atropine in incremental doses of 0.6 mg up to 1.8 mg. Because of the sneezing and restlessness, four patients in the atropine group required general anaesthesia to improve operating conditions. These side-effects of chlormethiazole may limit its use as a sedative for surgery in this elderly age group.
One Year's Experience in a New Dental Day-Stay Unit
Authors: Yee K. F. , Davis A. C.
Published: January 2019

The records of six hundred and fifty-five patients treated in the Dental Day-Stay Unit over a twelve-month period were reviewed. 2.1% of 95 patients assessed as suitable for day-stay surgery, and 2.2% of 542 patients not assessed prior to anaesthesia were admitted postoperatively. As an index of outcome, 2.56% of 547 day cases were admitted postoperatively, 0.73% being attributable to anaesthesia.

Forty-seven day patients were treated in the dental chair, and 108 were treated as inpatients. Over 37% had at least one concurrent medical problem, while 10.4% were mentally handicapped. Guidelines for day-care selection require that the procedure be straightforward, the patient medically fit, be discharged escorted, and live within a reasonable distance of the hospital. From our study, four specific patient groups are identified. These are: the young and healthy, the mentally handicapped, the medically compromised, and those with airway problems.
Effects of Anaesthesia on some Aspects of Mental Functioning of Surgical Patients
Authors: Flatt Jennifer R. , Birrell Peter C. , Hobbes Alick
Published: January 2019

Plastic surgery patients undergoing either local (LA) or general (GA) anaesthesia of at least forty-five minutes' duration and a non-patient control group were used to examine the extent and duration of deterioration in mental functioning following GA and the factors influencing such deterioration. Mental functioning was assessed by a battery of six tests administered one week before anaesthesia, four days after anaesthesia and six weeks after anaesthesia. Mental performance of GA patients but not of LA patients was significantly impaired on the fourth postoperative day. Six weeks after anaesthesia GA patients were still performing significantly below controls. There was marked variation in the pattern of recovery, some GA patients failing to regain their pre-operative level of performance after six weeks. Severity of deterioration following general anaesthesia was significantly correlated with habitual caffeine consumption.
A Comparative Study of Cardiac Output Measurement by Dye Dilution and Pulsed Doppler Ultrasound
Authors: Tibballs J. , Osborne A. , Hockmann M.
Published: January 2019

Dye dilution was compared with pulsed doppler for the measurement of cardiac output in eighteen children being ventilated after cardiac surgery. The mean difference between the two techniques was -0.04 l/min (dye minus doppler) with 95% confidence limits of 0.25 l/min and -0.33 l/min over a cardiac output range 0.27–6.12 l/min; this difference is not significant. Calculation of the product-moment correlation coefficient showed a close relationship between the dye dilution and doppler methods with r = 0.97. Pulsed doppler is a new noninvasive technique that can be used instead of dye dilution for the measurement of cardiac output in co-operative or anaesthetised children.
Cardiovascular Responses to Induction of Anaesthesia with Thiopentone and Suxamethonium in Infants and Children
Authors: Tibballs J. , Malbezin S.
Published: January 2019

Cardiac output, systolic blood pressure and heart rate were measured with non-invasive techniques before, during and after induction of anaesthesia with thiopentone (7.5–8.5 mg/kg) and suxamethonium (1.4–1.7 mg/kg), and after intubation in unpremedicated infants and diazepam-atropine premedicated children. Cardiac output was measured with a combination of M-mode and pulsed doppler echocardiography. Significant decreases in systolic blood pressure, cardiac index and stroke volume index were observed during induction in both infants and children. Intubation caused increases above pre-induction levels of heart rate, blood pressure and cardiac index in both infants and children. Stroke volume index increased marginally in infants but remained depressed in children after intubation. Left ventricular shortening fraction decreased significantly in five other children during induction. It is concluded that thiopentone causes significant reduction in cardiac output by depression of myocardial contractility manifested by depression of blood pressure and stroke volume. Premedication with atropine may ameliorate reduction in cardiac output by permitting an increase in heart rate during induction. Induction of anaesthesia with thiopentone and premedication with diazepam does not prevent hypertension and tachycardia occurring with intubation.
A Method of Detecting Oesophageal Intubation or Confirming Tracheal Intubation
Authors: O'Leary J. J. , Pollard B. J. , Ryan M. J.
Published: January 2019

A method of testing the location of an endotracheal tube, in the trachea or oesophagus, was subjected to trial. The test involves drawing back on the plunger of a 50 ml syringe connected with airtight fittings to the endotracheal tube connector, with the endotracheal tube cuff deflated. The ability to withdraw 30 ml of air confirms tracheal intubation. When marked resistance to withdrawal of the plunger occurs and on release the plunger rebounds to its original position the oesophagus has been intubated.

The method was 100% accurate in fifty intubations, 25 tracheal and 25 oesophageal. The technique has been in routine use by one author for several years without giving an incorrect answer and enthusiastic use by other authors is producing the same result.
Criteria for Estimating Likelihood of Difficulty of Endotracheal Intubation with the Macintosh Laryngoscope
Authors: Bellhouse C. P. , Doré C.
Published: January 2019

Many anatomical factors in difficult intubation at direct laryngoscopy have been evaluated. Lateral radiographs were taken of nineteen patients in whom tracheal intubation proved particularly difficult, and fourteen patients whose intubation was reasonably straightforward. Stepwise discriminant analysis was used to select the best measurements for distinguishing between the difficult and straightforward groups. The variables which together are most reliable in predicting likely difficulty in intubation are reduced atlanto-occipital extension, reduced mandibular space, and lastly, increased antero-posterior thickness of the tongue. A formula and graph have been derived to relate these variables with likelihood of difficulty, and a method has been described of applying this information at the bedside, without using X-ray examination, to estimate the likelihood of difficulty in intubating a new patient. Eighteen months’ experience of the application of this clinical evaluation have so far found it reliable.
Effect of Altered Environmental Temperature on Established Infection
Authors: Lewis G. B. H.
Published: January 2019

An alteration of ten degrees Celsius in environmental temperature significantly alters the mortality from severe established Escherichia coli and Staphylococcus aureus infection in mice. Many patients with severe infection are nursed in wards without air conditioning. It is suggested that even modest levels of environmental stress may influence their recovery.
Induction Using Fentanyl to Suppress the Intubation Response in the Cardiac Patient: What is the Optimal Dose?
Authors: Iyer V. , Russell W. J.
Published: January 2019

Eighty patients undergoing coronary artery surgery were randomly allocated to receive either 0, 2, 5, 10 or 15 jig/kg of fentanyl with induction of anaesthesia. Heart rate and blood pressure were measured before induction, after induction, and after intubation.

The effects of fentanyl dose on both heart rate and mean arterial pressure (MAP) were evaluated in terms of both the mean and group responses.

At all doses of fentanyl, mean heart rate increased after induction and rose further on intubation. The mean increase after induction was minimal at doses of 5 μg/kg and greater. The increase in heart rate after intubation was more difficult to block but with a fentanyl dose of 15 μg/kg, 87% of patients had heart rates below 100 bpm. As a group, the percentage of patients in whom the postintubation heart rate remained below 100 bpm increased progressively with the fentanyl dose.

In contrast, mean MAP fell at all dose levels after induction, the mean fall being about 30 mmHg at 5 μg/kg and greater. Mean MAP exceeded pre-induction values after intubation with 0 and 2 μg/kg, and progressive attenuation of the MAP rise was found as the dose of fentanyl increased.

The percentage of patients who did not exceed their preinduction MAP rose progressively with increasing dose of fentanyl with an ED50 of 3.7 μg/kg.

If a minimal fall in mean MAP after induction with no rise above preinduction MAP is the sole criterion, a fentanyl dose of about 3 μg/kg is recommended. If heart rate is to be kept below 100 bpm, a dose of at least 10 μg/kg should be used. However, this dose or greater will cause the MAP to fall in some patients to less than 70 mmHg. The choice of the most appropriate dose depends on the anaesthetist's view of the relative importance of avoiding tachycardia or hypotension in the patient with coronary artery disease.
Experience with Extracorporeal Membrane Oxygenation in Children More than One Month Old
Authors: Butt W. , Karl T. , Horton A. , Shann F. , Mullaly R.
Published: January 2019

Extracorporeal membrane oxygenation (ECMO) has been used at the Royal Children's Hospital, Melbourne, in the treatment of children with life-threatening respiratory or cardiac failure since May 1988. The main indications for its use are, first, the disease is thought to be reversible, second, the child will survive with an acceptable quality of life and, third, the child has an 80% chance of dying without ECMO. Seven of eighteen children receiving ECMO have survived to leave hospital, and all are functionally normal: these results are similar to international results. It would appear that ECMO is a useful therapy for some children with otherwise fatal cardiorespiratory failure.
One Hundred Sciatic Nerve Blocks: A Comparison of Localisation Techniques
Authors: Davies M. J. , McGlade D. P.
Published: January 2019

One hundred sciatic nerve blocks performed for surgery related to lower limb vascular disease were prospectively audited with respect to the techniques used for sciatic nerve localisation and the success rates achieved. Utilising a 22 gauge Quincke point needle, sciatic nerve localisation was performed by initially searching for paraesthesia, followed by the use of a low powered peripheral nerve stimulator. Overall there were 89 successful blocks. Paraesthesia was found in only 44 cases of which 41 were subsequently judged to be successful blocks. A positive response to the nerve stimulator was achieved in 95 cases of which 87 went on to have successful blocks. Our findings suggest that either eliciting paraesthesia or a positive response to the peripheral nerve stimulator carries a high correlation with subsequent successful block, but that the use of the nerve stimulator provides a more consistent and reliable technique for nerve localisation.
The Capnograph: Applications and Limitations —An Analysis of 2000 Incident Reports
Authors: Williamson J. A. , Webb R. K. , Cookings J. , Morgan C.
Published: January 2019

The first 2000 incidents reported to the Australian Incident Monitoring Study were analysed with respect to the role of the capnograph. One hundred and fifty-seven (8%) were first detected by a capnograph and there were a further 18 (1%) in which capnography was contributory.

Of the 1256 incidents which occurred in association with general anaesthesia 48% were “human detected” and 52% “monitor detected”. The capnograph was ranked second and detected 24% of these monitor detected incidents; this figure would have been nearly 30% if a correctly checked, calibrated capnograph had always been used. The capnograph is a “front-line” monitor for oesophageal intubation, failure of ventilation, anaesthetic circuit faults, gas embolism, sudden circulatory collapse and malignant hyperthermia. It is a valuable “back-up” monitor when other monitors (e.g. low pressure alarm, pulse oximeter) are not in use, are being used incorrectly or fail. Such situations, in order of frequency of detection were: circuit-leak, overpressure of the breathing circuit, bronchospasm, leak of ventilator-driving-gas into the patient circuit, aspiration and/or regurgitation and hypoventilation.

There were 20 reports of “failure”, over two-thirds of which would not have occurred with appropriate checking and calibration. Seven were due to gas sampling problems and 6 to apnoea alarm failure. Two circuit leaks and 2 faulty unidirectional valves were not detected; on 3 occasions problems occurred due to power failure, calibration problems, or misinterpretation of an alarm.

In a theoretical analysis of the 1256 general anaesthesia incidents it was considered that the capnograph, used on its own, would have detected 55% of these incidents, had they been allowed to evolve (43% before any potential for organ damage).

It is highly recommended that a suitable, correctly checked, calibrated capnograph be used on all intubated and/or ventilated patients from the moment of intubation until extubation; capnography is also useful in the “apnoea” detection mode for patients breathing spontaneously on a mask.
The Electrocardiograph: Applications and Limitations—An Analysis of 2000 Incident Reports
Authors: Ludbrook G. L. , Russell W. J. , Webb R. K. , Klepper I. D. , Currie M.
Published: January 2019

The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed with respect to the role of the electrocardiograph (ECG). Of these, 138 (7%) were first detected by the ECG. Of the 1256 incidents which occurred in association with general anaesthesia (GA incidents) 48% were “human detected” and 52% “monitor detected”, the ECG was ranked third and detected 121 (19%) of these monitor detected GA incidents. However over 98% of incidents first detected by the ECG were heart rate changes; they would also have been detected by a pulse meter or pulse oximeter which would have supplied additional information about the adequacy of peripheral perfusion.

The ECG is a “first-line” monitor in situations with the potential for myocardial ischaemia, complex dysrhythmias or altered myocardial conduction and should be used in all critically ill patients as well as those at significant risk of these problems. The ECG frequently detects incidents involving minor physiological trespass, such as simple heart rate and rhythm changes associated with anaesthetic agents. These incidents are generally detected relatively early in their evolution. AIMS data has confirmed, however, that the ECG has such poor sensitivity for serious physiological changes such as hypoxia, hypercarbia and hypotension that it cannot even be regarded as a useful “back-up” monitor for these problems. Indeed a “normal” ECG in a dangerous situation may lead to a degree of complacency.

Because the anaesthetist cannot differentiate between these minor and serious causes of ECG changes, it was decided, for a theoretical analysis, that although the ECG used on its own would have detected 55% of the 1256 GA incidents, had they been allowed to evolve, it could not be assumed that it would do so without potential for organ damage. The ECG may be regarded as an adjunct to, but does not replace, an oxygen analyser, pulse oximeter, capnograph, or high pressure alarm. An ECG should always be available but need not be used for young fit patients unless specifically indicated.
Human Failure: An Analysis of 2000 Incident Reports
Authors: Williamson J. A. , Webb R. K. , Sellen A. , Runciman W. B. , Van Der Walt J. H.
Published: January 2019

Information of relevance to human failure was extracted from the first 2,000 incidents reported to the Australian Incident Monitoring Study (AIMS). All reports were searched for human factors amongst the “factors contributing”, “factors minimising”, and “suggested corrective strategies” categories, and these were classified according to the type of human error with which they were associated. In 83% of the reports elements of human error were scored by reporters. “Knowledge-based errors” contributed directly to about one-quarter of incidents; the outcome of one third of incidents was thought to have been minimised by prior experience or awareness of the potential problems, and in one fifth some strategy to improve knowledge was suggested. Correction of “rule-based errors” or provision of protocols or algorithms were thought, together, to have a potential impact on nearly half of all incidents. Failure to check equipment or the patient contributed to nearly one-quarter of all incidents, and inadequate crisis management contributed to a further I in 8. “Skill-based errors” (slips and lapses) were directly responsible for I in 10 of all incidents, and were thought to make an indirect contribution in up to one quarter. “Technical errors” were responsible for about 1 in 8 incidents. Analysing the relative contribution of each type of error for each type of problem allows the development of rational preventative strategies. Continued efforts must be made to improve the knowledge-base of anaesthetists, but AIMS has shown that there may also be much to gain from directing attention towards eliminating rule-based errors, for promoting the use of protocols, check-lists and crisis management algorithms, and improving anaesthetists’ insight into the factors contributing and circumstances in which slips and lapses may occur. Traditional patterns of behaviour in doctors may also make them more liable to certain types of human error; removing the onus for adhering to standards and approved work practices from the individual to the “system” may lead to more consistent application of the “best practice”.
Awareness under Anaesthesia: The Patients’ Point of View
Authors: Cobcroft M. D. , Forsdick C.
Published: January 2019

The collective experience of 187 patients who suffered awareness during general anaesthesia is presented. This has been collated from letters solicited in September 1992 by a women's magazine widely distributed throughout Australia and New Zealand. The responses cover anaesthetics given during a period from the 1950s to the present. The findings show a disturbing symptomatology ranging over almost all modalities of sensation and of postoperative psychological and psychiatric disturbances. The letters also reveal that in most cases understanding of awareness and its proper management by medical personnel was poor or totally lacking.
Incidence of Ventricular Fibrillation after Aortic Cross-Clamp Release using Lignocaine Cardioplegia
Authors: Wallace S. R. , Baker A. B.
Published: January 2019

The occurrence of ventricular fibrillation after aortic de-clamping during cardiac surgery is common, and if prolonged may contribute to myocardial ischaemia. The use of lignocaine cardioplegia to minimize reperfusion ventricular fibrillation was studied in 141 patients undergoing first time coronary artery surgery in a double blind prospective randomized trial: 71 patients received lignocaine 100 mg/l in their cardioplegia, whereas a control group of 70 patients received cardioplegia without lignocaine.

Lignocaine cardioplegia reduced significantly the incidence of reperfusion ventricular fibrillation from 63% to 42%. Of those patients developing reperfusion ventricular fibrillation, a higher proportion receiving lignocaine cardioplegia underwent spontaneous defibrillation (30% vs 11%) though this was not statistically significant.

The incidence of atrio-ventricular (A-V) block necessitating ventricular pacing to separate from cardiopulmonary bypass was significantly higher in the lignocaine treated group (44%) than in the control group (20%): this may have been due to the additive effect of procaine in the cardioplegia solution. In the majority of cases this A-V block was transient and had resolved prior to the completion of surgery.
Tunnelled Epidural Catheters for Routine Use: Description of a Technique
Authors: Pavy T. J. G.
Published: January 2019

A simple technique for routine tunnelling of epidural catheters is described. It represents a simplified version of subcutaneous tunnelling as commonly performed in chronic pain patients. In 200 obstetric and gynaecological patients to date, only two catheters have become dislodged prematurely.
Inguinal Field Block for Adult Inguinal Hernia Repair Using a Short-Bevel Needle. Description and Clinical Experience in Solomon Islands and an Australian Teaching Hospital
Authors: Sparks C. J. , Rudkin G. E. , Agiomea K. , Faarondo J. R.
Published: January 2019

One of the limitations of an inguinal field block is that it does not reliably produce complete anaesthesia. The purpose of this study was to describe a modified short-bevel needle technique, facilitating correct needle placement, for inguinal hernia repair. Anaesthetists from two different institutions performed the described infiltration blocks. Prospective data were collected from these groups, each having 30 patients. We evaluated the safety and reliability of the described block. Of the 60 patients, two were “failed” blocks, requiring conversion to general anaesthesia. There were no other major intraoperative or recovery room complications. Results of the modified inguinal field block showed a 97% ability to achieve a “fair” block or better. Intraoperative and postoperative data showed high surgeon and patient satisfaction for the block. The described block using a short-bevel needle is recommended as a suitable method for adult patients undergoing inguinal hernia repair.
Problems in the Modelling of Inert Gas Kinetics
Authors: Gorman D.
Published: January 2019

The models used to describe the kinetics of inert gases during underwater diving are inadequate. Medical practitioners and scientists interested in such diving have attempted to quantitatively describe the behaviour of nitrogen in compressed air diving since 1908, with little success. The problems encountered during this diving research are relevant to anaesthesia theory and practice.
Comparison in Spontaneous Ventilation of the Maxima with the Humphrey ADE Breathing System and between Four Methods for Detecting Rebreathing
Authors: Miller D. M. , Palm A.
Published: January 2019

An enclosed efferent, afferent reservoir breathing system (Maxima, Life Air Pty Ltd), being valveless, was compared to a simple afferent reservoir system (Humphrey ADE, A mode), having a valve, by assessing fresh gas flow (V̇F) requirements, with respect to ventilation (V̇E), that prevents rebreathing in volunteers, awake and breathing spontaneously. The results are recorded in terms of the quotient V̇F/V̇E associated with the onset of rebreathing. At the same time four clinical methods for assessing rebreathing were evaluated from the perspective of suitability for practical application during anaesthesia.

No significant difference was found in the VF requirements between the ADE and Maxima breathing systems with respective values obtained for the quotient VF/VE of 0.80 and 0.77.

Our findings showed that the method of sampling carbon dioxide (CO2) at the outflow of the efferent limb of the patient connector (eliminated CO2 method) in both afferent reservoir systems provided the highest flow rate and most reliable indication for detecting potential or actual rebreathing, when attempting to minimize VF. It provides no additional deadspace or resistance to gas flow, and has the advantage of being the only qualitative method that is reliable for the purpose of detecting the onset of rebreathing.
Effects of Midazolam on Heart Rate Variability during Surgery under Spinal Anaesthesia
Authors: Kawamoto M. , Shimokawa A. , Takasaki M.
Published: January 2019

Effects of midazolam on the cardiac autonomic nervous system were studied by power spectral analysis of electrocardiographic R-R intervals in patients undergoing elective lower abdominal surgery under spinal anaesthesia. Patients were randomly assigned into two groups: 10 patients in group A received spinal anaesthesia only and 10 in group S received spinal anaesthesia and midazolam of 0.05 mg/kg when surgery started. In the frequency domain power spectra, low (Lo; 0.04–0.15 Hz) and high (Hi; 0.15–0.40 Hz) frequency components were integrated to ascertain sympathetic and parasympathetic activity, respectively. There was no intergroup difference in starting time of surgery, ventilatory frequency, arterial pressure, heart rate, mean and variance of R-R interval, and cephalad level of analgesia. In spectral component, Lo decreased (P<0.05) and Hi/Lo ratio increased (P<0.05) relative to their baselines in group S. These were also different from group A (P<0.05). We concluded that intravenous midazolam depressed sympathetic activity to produce a vagotonic cardiac autonomic nervous system under spinal anaesthesia.
Decision-Making in Anaesthesia
Authors: Rudge B. A.
Published: January 2019

Anaesthetists work as part of a process and deal with complex situations in their daily work. Considerable effort is put into training anaesthetists, but little has been done either in research or improving awareness of the intangible components of the anaesthesia system that affect safety, such as decision-making. The purpose of this article is to apply the principles of decision-making to anaesthesia practice.
The Australian Incident Monitoring Study in Intensive Care: AIMS-ICU. An Analysis of the First Year of Reporting
Authors: Beckmann U. , Baldwin I. , Hart G. K. , Runciman W. B. ,   Intensive Care Units participating in the AIMS-ICU project
Published: January 2019

The AIMS-ICU project is a national study set up to develop, introduce and evaluate an anonymous voluntary incident reporting system for intensive care. ICU staff members reported events which could have reduced, or did reduce, the safety margin for the patient. Seven ICUs contributed 536 reports, which identified 610 incidents involving the airway (20%), procedures (23%), drugs (28%), patient environment (21%), and ICU management (9%). Incidents were detected most frequently by rechecking the patient or the equipment, or by prior experience. No ill effects or only minor ones were experienced by most patients (short-term 76%, long-term 92%) as a result of the incident. Multiple contributing factors were identified, 33% system-based and 66% human factor-based. Incident monitoring promises to be a useful technique for improving patient safety in the ICU, when sufficient data have been collected to allow analysis of sets of incidents in defined “clinical situations”.
Central Venous Catheters Revisited— Infection Rates and an Assessment of the New Fibrin Analysing System Brush
Authors: van Heerden P. V. , Webb S. A. R. , Fong S. , Golledge C. L. , Roberts B. L. , Thompson W. R.
Published: January 2019

Sixty-one consecutive patients in the Intensive Care Unit requiring central venous lines (CVC) for five or more days were randomized to receive either a standard triple lumen CVC (STD/CVC) or a silver sulphadiazine and chlorhexidine impregnated CVC (SSD/CVC). Data from the 54 patients who completed the trial show a reduced infection rate (positive tip culture) in the SSD/CVC group (4 out of 28) compared to the STD/CVC group (10 out of 26) (P<0.05).

In addition, the new Fibrin Analysing System (FAS) brush was evaluated and used to determine the presence of infection in all the CVCs (STD/CVC and SSD/CVC combined, n=54) at day 3 (i.e. early warning of CVC colonization/infection) and at the time of removal of the CVC. The FAS brush was able to detect an infected CVC on only one occasion on day 3 out of the 14 CVC tips which were later found to be colonized/infected at the time of removal. The sensitivity of the FAS brush in detecting colonized/infected CVCs at the time of CVC removal compared with CVC tip culture was 21% with a specificity of 100%. These findings would currently not support the routine use of the FAS brush in determining CVC infection/colonization.
Overheating Alone Can Trigger Malignant Hyperthermia in Piglets
Authors: Denborough M. , Hopkinson K. C. , O'Brien R. O. , Foster P. S.
Published: January 2019

Seven out of eight piglets which were susceptible to malignant hyperthermia (MHS) died when subjected to a heat challenge which was well tolerated by controls. The piglets which succumbed developed the classical clinical and biochemical changes of malignant hyperthermia before they died. These results show that overheating alone can trigger malignant hyperthermia in susceptible animals. Because the biochemical basis of malignant hyperthermia is similar in both humans and pigs, these observations suggest that overheating can also trigger malignant hyperthermia in humans. The susceptibility to overheating in malignant hyperthermia susceptible humans and animals probably explains why the myopathy which predisposes to this condition has also been reported to predispose to heat-stroke and the sudden infant death syndrome. In view of this, particular care to prevent overheating should be taken in infants of parents who are susceptible to malignant hyperthermia.