Contamination of the central medical air supply with water leading to mass ventilator failure.

Here, we present a case of mass ventilator failure due to contaminated medical air. Multiple ventilators failed routine tests, including almost all of the ventilators in our intensive care unit. A faulty air compressor had led to water contamination of our centre's supply of medical air. Water entered the pipeline supply of air and, hence the ventilators and anaesthetic machines. The disruption of the machines' proportional mixer valve resulted in unreliable delivery of fresh gas flow. This malfunction was discovered during routine pre-use checks, and backup ventilators were available to replace the faulty ventilators. A shortage of equipment was averted due to a serendipitous availability of ventilator stockpiles prepared for the COVID-19 pandemic. Ventilator shortages are commonly described in mass casualty and pandemic scenarios. While there are multiple strategies described in literature to augment and maximise equipment available for mechanical ventilation, stockpiling equipment remains an expensive but necessary component of disaster contingency planning.

Occult pneumothorax in blunt trauma: is there a need for tube thoracostomy?

INTRODUCTION/BACKGROUND: Occult pneumothorax (OPTX) is defined as air within the pleural cavity that is undetectable on normal chest X-rays, but identifiable on computed tomography. Currently, consensus is divided between tube thoracostomy and conservative management for OPTX. METHODS: The aim of this retrospective study is to determine whether OPTX can be managed conservatively and whether any adverse events occur under conservative management. Data on all trauma patients from 1 Jan 2010 to 31 December 2012 were obtained from our hospital's trauma registry. All patients with occult pneumothorax who had chest X-ray (CXR) and any CT scan visualizing the thorax were included. The exclusion criteria included those with penetrating wounds; CXR showing pneumothorax, hemothorax, or hemopneumothorax; those with prophylactic chest tube insertion before CT; and those with no CT diagnosis of OPTX. The complications of these patients were analyzed to determine if tube thoracostomy is necessary for OPTX and whether not inserting it would alter the outcome significantly. RESULTS: A total of 1564 cases were reviewed and 83 patients were included. Of these 83 patients, 35 (42.2 %) had tube thoracostomy after OPTX detection and 48 (57.8 %) were observed initially. Patients who had tube thoracostomy had similar ISS compared to those without (median ISS 17 vs. 18.5, p = 0.436). Out of the 48 patients who did not have tube thoracostomy on detection of an OPTX, 4 (8.3 %) had complications. In the group of 35 patients who had tube thoracostomy on detection of an OPTX, 7 (20 %) had complications. Of the 83 patients, a total of 12 patients had IPPV, of which 7 (58.3 %) had tube thoracostomy and 5 (41.7 %) did not. Patients who had tube thoracostomy under our care have a statistically significant likelihood of experiencing any complication compared to those without tube thoracostomy (odds ratio 9.92. The median length of stay was also longer (13 days) in those who had tube thoracostomy compared to those without (5 days) (p value = 0.008). CONCLUSIONS: Our study suggests that patients with OPTX can be managed conservatively with close monitoring, but only in areas with ready access to emergency facilities should any adverse events occur.

Non-operative management of obturator hernia in an elderly female.

Obturator hernia is a rare surgical condition, with about 800 cases being reported in the literature. It can cause significant morbidity and mortality, especially in the elderly age group. Delayed treatment is associated with high rates of strangulation (25-100 %). The mainstay of management for obturator hernia has been surgical. Non-operative management can lead to significant morbidity and mortality, but may be an option in patients who decline surgery, as described in our case.

Problems related to epidural analgesia for postoperative pain control.

INTRODUCTION: Epidural analgesia provides excellent analgesia after major surgery but it is not without adverse effects. This retrospective study aims to evaluate the efficacy of analgesia and the problems commonly encountered postoperatively. MATERIALS AND METHODS: Elective surgical patients who had epidural catheters inserted perioperatively intended for postoperative analgesia over a 1-year period were studied. Anaesthetic charts and daily records of patient evaluation by the Acute Pain Service (APS) for pain relief, side effects and their subsequent management were analysed. RESULTS: A total of 471 patients had epidural catheters inserted for postoperative analgesia. Ninety per cent of patients received continuous local anaesthetic infusion (75% ropivacaine and 15% bupivacaine) and 10% received intermittent morphine boluses. There were few serious complications but 60% of patients required one or more interventions by the APS, mainly for inadequate analgesia. One-third of patients had their epidural analgesia terminated prematurely due to inadequate analgesia (14.2%), shortage of beds in the high-dependency unit (14%) and other complications. Only 19% of patients had no reported adverse effects. CONCLUSION: Although the incidence of serious complications was low, there was a high incidence of minor adverse effects especially during the first 48 hours. This emphasises the importance of close monitoring during the early postoperative period and the APS in the management of side effects, especially inadequate analgesia.

Tracheal intubation by novice staff: the direct vision laryngoscope or the lighted stylet (Trachlight)?

OBJECTIVE: To compare the ease of use of the direct vision laryngoscope and the lighted stylet (Trachlight) by novice staff. METHODS: Ten novice medical officers (MOs) performed orotracheal intubations using either the conventional direct vision laryngoscope (DL) or a lighted stylet device (Trachlight). They performed their DL intubations during the first phase of the study, followed by the Trachlight intubations in the subsequent phase. RESULTS: 51 of 54 (94%) of the DL intubation attempts were successful compared with 36 of 54 (67%) of the Trachlight intubations (p<0.001). The mean (SEM) time for intubation was 44 (7) seconds in the DL group and 66 (13) seconds in the Trachlight group (p=0.004). In addition 45 of 54 (83%) of the DL intubations were successful at the first attempt versus 15 of 54 (28%) in the Trachlight group (p<0.001). CONCLUSION: The results show that the use of the conventional direct vision laryngoscope in novices is associated with significantly shorter mean intubation times and higher success rates on the first attempt compared with the Trachlight.

The effect of heat and moisture exchanger and gas flow on humidity and temperature in a circle anaesthetic system.

OBJECTIVE: The aim of the study was to measure the humidity and temperature of the inspired gas in a circle absorber system at fresh gas flows of 11/min and 31/min and assess the need of a heat and moisture exchanger (HME). METHODS: This prospective randomised controlled study received the Hospital Ethics Committee approval and informed consent. Forty adult ASA 1 and 11 patients were randomised into four groups to receive with or without HME fresh gas flow of 1L/min or 3L/min. Temperature and the relative humidity readings were taken at the start and every 10 minutes for the first hour of anaesthesia. RESULTS: There was a significantly higher relative humidity, absolute humidity and temperatures of the inspired gases at fresh gas flow of 1L/min and 3L/min with a HME compared to 3L/min without HME. Patients receiving fresh gas flows of lL/min had higher relative and absolute humidity than patients with fresh gas flows of 3L/min. However, the addition of the HME improved the absolute and relative humidity of the inspired gas in patients receiving fresh gas flow of 3l/min to a comparable level. However, the addition of a HME to a fresh gas flow of 1L/min did not significantly improve the humidity of the inspired gas. CONCLUSION: This suggests that the inherent humidifying property of the circle system at low fresh gas flow of 1L/min was sufficient in short surgeries lasting less than one hour and that the addition of a HME may not be necessary.

Clinical evaluation of the Mapleson theoretical ideal fresh gas flow sequence at the start of low-flow anaesthesia with isoflurane, sevoflurane and desflurane.

Mapleson used a computer spreadsheet model to predict the theoretical ideal fresh gas flow sequence at the start of low-flow anaesthesia. The aim was to increase the end-expired partial pressure of inhalational agent (PE'an) to one minimum alveolar concentration (MAC) as quickly as practicable and then to keep it constant. Ninety adult patients undergoing elective tonsillectomy under general anaesthesia were randomly allocated to one of three groups (n = 30) to receive isoflurane, sevoflurane or desflurane in oxygen. Fresh gas flow and vaporiser settings as specified by Mapleson were followed in all cases except that the maximum setting for desflurane was 18% (2.7 MAC instead of 3 MAC). Recordings of PE'an were made at 1, 2, 3, 4, 5, 7, 10, 15 and 20 min. Mean values of PE'an exceeded 1 MAC by 2 min in all three groups and remained above this value throughout. Each group's PE'an measurements were divided by their respective 1-MAC value. A simple two-level model (with patients at level 2 and time at level 1), with measurements at 1 min excluded, showed that the fitted value at 2 min and the time-weighted mean for 2-20 min for PE'iso (1.042 [95% CI 0.980-1.104] and 1.044 [0.984-1.104], respectively) were not significantly different from its 1-MAC value, whereas those of the PE'sevo (1.169 [1.119-1.219] and 1.143 [1.119-1.219]) and PE'des (1.305 [1.261-1.349] and 1.140 [1.098-1.182]) were significantly higher than their respective 1-MAC values. The Mapleson concept of an initial high fresh gas flow and high vaporiser settings, followed first by reduced high fresh gas flow, as followed in this clinical study, results in PE'an values close to or slightly higher than predicted in the spreadsheet model.

The predictive value of intraoperative ST-segment monitoring as a marker of myocardial injury.

AIM: To evaluate the usefulness of dynamic intraoperative ST-monitoring in high-risk patients comparing it to preoperative clinical assessment and concurrent biochemical markers of cardiac injury. MATERIALS AND METHODS: Twenty-three patients clinically assessed as being at high risk for perioperative cardiac complications were recruited into this prospective, observational study in a public hospital. All had serial ECGs, cardiac enzymes and troponin-T measurements. The sensitivity, specificity, positive and negative predictive value of ST-segment changes in terms of predicting cardiac complications were calculated. We investigated the relationship between ST changes and biochemical markers of ischaemia and the predictive value of nonspecific (ASA) and specific (Goldman) clinical scores for cardiac complications. RESULTS: When correlated with cardiac complications, ST-segment monitoring had sensitivity 45.4%, specificity 100%, positive predictive value 100% and negative predictive value 66.7%. The correlation with CK-MB and troponin T was sensitivity 16.7% and 25%, specificity 73.3% and 75%, positive predictive value 20% and 20%, and negative predictive value 68.8% and 80%, respectively. The percentage of patients with cardiac complications increased with poor Goldman and ASA clinical scores; 25%, 40%, 62.5% and 100% in Goldman risk index groups of 0-5, 6-12, 13-25 and > 25, respectively; and 33.3% and 52.6% in ASA II and ASA III, respectively. CONCLUSIONS: This study demonstrates the importance of the anaesthesiologist preoperative assessment of cardiac risk. The probability that a patient with significant ST-depression will develop subsequent cardiac complications is 100%, which reflects its usefulness in this high-risk pre-selected sample. However, the test has a low sensitivity (45.4%).

Fibre-optic aided bougie (FAB) for simulated difficult tracheal intubation.

INTRODUCTION: Difficult intubation remains a key problem and the value of the gum elastic bougie as a first approach is well recognised. MATERIALS AND METHODS: A fine fibre-optic endoscope (Rapiscope, Cook Critical Care) was used in 50 patients to verify placement of a custom-designed hollow plastic bougie prior to "rail-roading" a tracheal tube. Following induction and muscle relaxation, direct laryngoscopy was performed after two-minutes of assisted ventilation. The laryngoscope blade was lowered to simulate difficult intubation and the bougie passed behind the epiglottis. The position of the introducer bougie was then checked using the Rapiscope. Following correct bronchoscopic identification of the tracheobronchial anatomy, a tracheal tube was then "rail-roaded" following withdrawal of the scope. RESULTS: All patients were successfully intubated following identification of the bronchial tree by the Rapiscope: three on the second attempt and the rest on the first. Mean (SD, range) time to successful bronchoscopic confirmation of correct placement of the bougie was 38 s (9.1 s, 19 to 60 s). All bronchoscopic assisted intubation were subsequently confirmed by capnography after tracheal tube insertion. Mean (SD, range) time to successful intubation was 106 s (14 s, 52 to 132 s). CONCLUSION: The fibre-optic assisted bougie (FAB) offers a promising technique in patients who may be difficult to intubate but who can be ventilated. Further developments are required to achieve a faster intubation time but oxygenation may be achieved by jetting down the hollow bougie.

Anterior mediastinal masses: an anaesthetic challenge.

A patient with a large anterior mediastinal mass with minimal respiratory symptoms presented for a diagnostic biopsy of the mass. A pre-operative thoracic computed tomographic scan demonstrated narrowing of the distal trachea, and right and left main stem bronchi. An awake intubation was done. Thiopentone and muscle relaxant were given and surgery commenced. High airway pressure developed and ventilation became difficult, although oxygenation remained satisfactory throughout. Anaesthetic implications are discussed. We recommend that patients with more than 50% obstruction of the airway at the level of the lower trachea and main bronchi have their femoral vessels cannulated in readiness for cardiopulmonary bypass.

An in vitro evaluation of epidural catheters: tensile strength and resistance to kinking.

The tensile strengths of 12 commercially available brands of epidural catheters were assessed using an Instron material testing device. The mean values of the tensile strengths ranged from 1.89 to 3.74 kilogram force. The extent of catheter occlusion due to kinking was also studied using an in vitro apparatus designed to simulate drug delivery at various degrees of flow restriction. It was determined that reinforced catheters were less likely to be occluded secondary to kinking.

Predictors of long-term outcome in severe head injury.

Severe head injury is associated with significant morbidity and mortality. We conducted a retrospective study to assess the long-term outcome of these patients using the Glasgow Outcome Score (GOS) and evaluate the variables that might predict outcome. Data were collected from all post-traumatic neurosurgical patients with severe head injury (Glasgow Coma Scale 8 or less) admitted to the Surgical Intensive Care Unit over a 29-month period. The long-term outcome was assessed one year after the injury by a telephone interview or a review of the hospital records. Seventy patients satisfied the criteria for the study. The male to female ratio was 9:1. The mean age of the patients was 37 (range 17 to 84) years. The overall mortality was 50%. Patients with a poor outcome (defined as GOS scores of 1 to 3) had a significantly higher mean age, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and a lower Glasgow Coma Scale than those with a good outcome (GOS 4 to 5). The APACHE II score correlated better with outcome than the Glasgow Coma Scale or age. The APACHE II score may be used to prognosticate the long-term outcome in severe head injury.

The effectiveness of systematic stroke care.

A coordinated, multidisciplinary approach had been applied to enhance the effectiveness of stroke care with varying enthusiasm; however, the effectiveness of this kind of stroke treatment model was noted in many studies. This study was designed to measure the effectiveness of systematic stroke management on the physical-functional outcome in terms of Activities of Daily Living (ADLs) scores. The higher the ADLs score, the higher the degree of physical disability, i.e., the higher the degree of dependence. Eighty-six stroke patients from the Department of Neurology in a medical center, and 88 stroke patients from the Department of Medicine in a local hospital were followed from the admission day to the discharged date. The effectiveness of stroke care in each hospital was measured by the comparisons between ADLs scores at discharge and ADLs scores at admission. Two-sample tests show that demographic characteristics, length of stay, average time elapsed since the occurrent stroke, number of families in caregiving, and ADLs scores at admission and at discharge did not differ much between these two groups. The improved ADLs scores for stroke patients treated in the Department of Neurology of the medical center were changed from the 14.1 +/- 4.9 at admission to 12.1 +/- 5.2 at discharge, and the changes of ADLs scores for patients treated in the Department of Medicine of the regional hospital was from 12.8 +/- 5.1 to 12.3 +/- 5.5 according to the degree of improvement. The significant finding was that the degree of improvement of ADLs scores for CVA patients from the medical center was significant (Wilcoxon Matched-Pairs Signed-Ranks Test, Z = -2.8, p < 0.01). Moreover, the degree of improvement of ADLs scores strongly differed between these two groups (Repeated measures of two-way ANOVA, F = 6.0, p < 0.05). The information presented here informs us that degree of physical-functional status of stroke patients should be improved because of the systematic stroke management.

Validation of APACHE II score in a surgical intensive care unit.

The APACHE II scoring system was applied to 301 surgical intensive care admissions over a 9-month period. The mean age of patients admitted was 52.39 years (SD 19.3) and the mean duration of stay was 5.37 days (SD 8.93). The overall mortality was 17.27%. The mean APACHE II scores for survivors was 12.94 (SD 7.43) and non-survivors 28.19 (SD 10.43). There was good correlation between expected mortality predicted by the APACHE II system and observed mortality (r = 0.9732). Using a predicted risk criterion of 0.5 to distinguish between those predicted to survive and die, of the 45 patients predicted to die, only 30 actually did so. No patient survived with an APACHE II score of more than 40 and with a predicted risk of death greater than 0.87. We found the APACHE II system useful for evaluating ICU performance and risk stratification for the purpose of therapeutic trials but not as a triage tool.

The effect and mechanism of the prokinetic action of cisapride on gastrointestinal smooth muscle.

Cisapride is a new prokinetic agent which can facilitate or restore motility throughout the entire gastrointestinal tract. Although facilitation of acetylcholine release has been suggested, the mechanism of action of cisapride is not clear. To investigate the effect and mechanism of action of cisapride, we used isolated muscle strips (with mucosa and submucosa removed) of guinea pig antrum, ileum and colon to study: (1) the dose response to cisapride, (2) the effect of antagonists (atropine and tetrodotoxin) on the stimulatory effect of cisapride. Besides these studies, we also used 3H-acetylcholine release method to investigate the acetylcholine release effect of cisapride. Cisapride elicited a dose-related enhancement of baseline activity (motility index) on the antrum and contraction on the ileum and colon at the dose of 4, 40 and 400 nM. At higher doses (4 microM) cisapride caused inhibition. This bell-shaped dose response curve suggested that cisapride might be autoinhibitory or that the receptors of cisapride might consist of high affinity stimulatory and low affinity inhibitory sites. The stimulatory responses elicited by cisapride (400 nM) were not significantly inhibited by atropine and tetrodotoxin in the antrum, ileum and colon. This suggested that cisapride might act directly on the smooth muscle. Cisapride (400 nM) evoked a rather small increase of 3H-acetylcholine release on the antrum, ileum and colon. Because the percentage of increase was small and we had demonstrated that the stimulatory effects of cisapride were not blocked by atropine and tetrodotoxin, the acetylcholine release effect of cisapride was considered unimportant.

[Macro electromyography in motor neuron disease].

Macroelectromyography (macroEMG) is a technique that provides information about the size of a motor unit which the conventional EMG is not able to. We used macroEMG to study 11 cases of motor neuron disease (MND), presenting with upper extremities symptoms (no lower extremities symptoms). Muscles we selected to study were the biceps brachii and the tibialis anterior. Amplitude, area and fiber density (FD) were analysed. The controlled groups consisted of 11 cases of myasthenia gravis (MG) and 11 normal subjects. Our study demonstrated that in the MND group, amplitude, area and FD of both muscles were significantly increased over those of the normal subjects. We also found that the amplitude and area of biceps brachii in patients who had clinical symptoms less than 2 years, were significantly higher than those over 2 years. However, there were no significant differences between the two groups of the tibialis anterior. This was probably due to the fact that the disease process was not severe enough to cause significant differences. Further follow up studies are necessary to clarify this question. In MG, amplitude, area and FD were not significantly different than those of the normal subjects. Increased amplitude, area and FD in MND provides information regarding the reinnervation process of the disease. As the disease progresses, the above findings may decrease because the motor neurons can no longer support the enlarged motor unit. All of the MND patients in our study, had no symptoms in the lower extremities; however, we found there were significant changes in the macro-EMG findings of the tibialis anterior. This indicates that macro-EMG can detect early electrophysiological changes in the motor unit before clinical symptoms develop.