PubMed Health⌕ Search

Biomedical subjects

D A Story

Publications and source records attributed to D A Story.

At least 19 recordsLinked to original sources
PubMed2006

Effect of an anaesthesia department led critical care outreach and acute pain service on postoperative serious adverse events.

UNLABELLED: We examined whether a combined critical care outreach and acute pain service comprising both medical and nursing staff from the Department of Anaesthesia would decrease the incidence of postoperative serious adverse events in a hospital with an established Medical Emergency Team. We called this combined service IMPACT: Inpatient Management of acute Pain and Advice on Clinical Treatment. We conducted a prospective, before-and-after trial with a baseline phase (319 patients) of standard acute pain management followed by the IMPACT phase (271 patients), during which the IMPACT team systematically reviewed high-risk postoperative patients for the first three days after their return to the general wards. The incidence of serious adverse events decreased from 23 events per 100 patients to 16 events per 100 patients. The 30-day mortality decreased from 9% to 3%, p = 0.004. An acute pain service providing critical care outreach may improve postoperative outcome but the workload is considerable.

Aged↗
PubMed2006

Pulmonary arteriovenous malformation causing massive haemoptysis and complicated by coronary air embolism.

We report the case of a 20-year-old man with possible Osler-Rendu-Weber syndrome (hereditary haemorrhagic telangiectasia) who developed an episode of massive haemoptysis from a bleeding pulmonary arteriovenous malformation in the left lower lobe of his lung. During the acute haemorrhage, he also appeared to suffer a coronary air embolism, possibly due to introduction of air into the bleeding arteriovenous malformation during intermittent positive pressure ventilation through the endotracheal tube. His electrocardiogram showed extensive ST elevation (>2 mm) in the inferolateral leads associated with raised troponin I and creatine kinase levels. These changes resolved within thirty minutes. The pulmonary arteriovenous malformation was successfully treated with a combination of alcohol injection and coil embolization.

Abnormalities, Multiple↗
PubMed2006

Tracheal resection for critical tracheal occlusion due to intraluminal tumour.

Anaesthesia for tracheal resection requires careful planning by an experienced team. We report a case of urgent tracheal resection for a vascular tumor in a 41-year-old man who was a heavy smoker The tumour occupied most of his trachea. A CT reconstruction of the tumor assisted in planning. Perioperative tracheal laser therapy and cardiopulmonary bypass were not used due to concerns about excessive bleeding. Intraoperative airway management involved an upper endotracheal tube placed by the anaesthetist and a second, lower, endotracheal tube placed by the surgeon. The existing evidence for anaesthesia management of tracheal resection is currently limited to case reports. This case illustrates how preoperative imaging and careful planning can lead to a successful outcome, despite the potentially life-threatening nature of the pathology and the surgery.

Adult↗
PubMed2005

Biologically active contaminants of intravenous saline in PVC packaging: Australasian, European, and North American samples.

We have previously found evidence of contaminants in 0.9% saline packaged in polyvinyl chloride (PVC) for clinical use. For this current study we asked two questions: (1) what are the organic chemical contaminants in solutions packaged in PVC? and (2) do the contaminants vary in bags manufactured in different countries? We studied samples of 0.9% saline packaged in PVC from Australasia, Europe, and North America. We analysed the saline solutions with high-resolution capillary gas chromatography - mass spectrometry. Components of the Australasian and European bags were also analysed using thermodesorption followed by gas chromatography and mass spectrometry. In three pairs of samples we found twenty-four different organic contaminants of the saline solutions. Diethylhexyl phthalate (DEHP) was found in all solutions; the concentrations were greater than 10 microg/l in the Australasian and European samples. All samples contained 2-ethyl hexanol (>50 microg/l), a DEHP breakdown product. The Australasian and North American samples contained cyclohexanone at concentrations of about 1000 microg/l. The cyclohexanone probably originated in joints at the bases of the bags. Both the Australasian and European bags contained t-butyl cyclohexanol (>500 microg/l) and t-butyl cyclohexanone (>50 microg/l). Printing ink on the outside of the bags was the most likely source for both of these contaminants. Several of the contaminants are toxic to animals. Little is known about the toxicity of combinations of contaminants.

Australia↗
PubMed2005

Serotonin syndrome and the anaesthetist.

Serotonin syndrome results from excessive activation of serotonin (5-hydroxytryptamine; 5-HT) receptors in the nervous system, on the surface of platelets, and on the vascular endothelium. The clinical manifestations are a triad of altered conscious state, autonomic dysfunction, and neuromuscular excitability. Clinical diagnostic criteria remain poorly defined and unvalidated, and there are no available investigations to confirm the diagnosis. The syndrome is caused by the administration of one or more drugs possessing serotonergic activity. Severe forms of the syndrome usually result from overdose, but can be induced by monotherapy. The exact incidence of serotonin syndrome remains unknown, but is likely to be increasing due to increased prescription of selective serotonin reuptake inhibitor antidepressants and tramadol, as well as recreational use of amphetamine-like substances. Serotonin syndrome may complicate the administration of drugs frequently used in anaesthetic practice, including pethidine and tramadol. Although the majority of cases improve with symptomatic and supportive care, severe cases need intensive care and frequently require mechanical ventilation. Neuromuscular excitability is likely to be the cause of rhabdomyolysis seen in severe cases and should be treated with benzodiazepines and muscle relaxants. Supportive therapies are required to treat hyperthermia and autonomic dysfunction. Cyproheptadine is the most commonly administered serotonergic antagonist, but is unavailable in parenteral form.

Analgesics, Opioid↗
PubMed2005

Plasma acid-base changes in chronic renal failure: a Stewart analysis.

The bicarbonate centered approach to acid-base physiology involves complex explanations for the metabolic acidosis associated with chronic renal failure. We used the alternate Stewart approach to acid-base physiology to quantify the acid-base chemistry of patients with chronic renal failure. We examined the plasma and urine chemistry of 19 patients with chronic renal failure who were predialysis and 20 healthy volunteers. We compared the plasma strong-ion-difference due to sodium,potassium,and chloride ions as well as the weak acids albumin and phosphate. We used a simplified Fencl-Stewart approach to quantify the effects of sodium-chloride, albumin, and unmeasured ions on base-excess. The chronic renal failure group had a greater metabolic acidosis, with a base-excess that differed from the healthy group by a mean of -2.7 mmol/L, p = 0.04. This was associated with a strong ion acidosis due to both increased chloride and decreased sodium. The anion gap, strong-ion-gap, and base-excess effect of unmeasured ions were similar in both groups suggesting that unmeasured ions had only a minor role in the acid-base status in this group of patients.

Acid-Base Equilibrium↗
PubMed2004

Strong ions, weak acids and base excess: a simplified Fencl-Stewart approach to clinical acid-base disorders.

BACKGROUND: The Fencl-Stewart approach to acid-base disorders uses five equations of varying complexity to estimate the base excess effects of the important components: the strong ion difference (sodium and chloride), the total weak acid concentration (albumin) and unmeasured ions. Although this approach is straightforward, most people would need a calculator to use the equations. We proposed four simpler equations that require only mental arithmetic and tested the hypothesis that these simpler equations would have good agreement with more complex Fencl-Stewart equations. METHODS: We reduced two complex equations for the sodium-chloride effect on base excess to one simple equation: sodium-chloride effect (meq litre(-1))=[Na(+)]-[Cl(-)]-38. We simplified the equation of the albumin effect on base excess to an equation with two constants: albumin effect (meq litre(-1))=0.25x(42-[albumin]g litre(-1)). Using 300 blood samples from critically ill patients, we examined the agreement between the more complex Fencl-Stewart equations and our simplified versions with Bland-Altman analyses. RESULTS: The estimates of the sodium-chloride effect on base excess agreed well, with no bias and limits of agreement of -0.5 to 0.5 meq litre(-1). The albumin effect estimates required log transformation. The simplified estimate was, on average, 90% of the Fencl-Stewart estimate. The limits of agreement for this percentage were 82-98%. CONCLUSIONS: The simplified equations agree well with the previous, more complex equations. Our findings suggest a useful, simple way to use the Fencl-Stewart approach to analyse acid-base disorders in clinical practice.

Acid-Base Imbalance↗
PubMed2004

The effect of critical care outreach on postoperative serious adverse events.

We proposed that critical care outreach would decrease the incidence of postoperative serious adverse events and so conducted a sequential cohort study with a surveillance-only phase (baseline) followed by an intervention phase. We studied high-risk patients in a large Australian hospital. A critical care qualified nurse reviewed patients for the first three days after return to the general wards. During the intervention phase the nurse intervened in patient care where appropriate. We examined the incidence of 11 categories of serious adverse events per 100 patients during the first three days on the general wards during the surveillance and intervention phases. The surveillance phase had 319 patients and the intervention phase 345 patients. In a subgroup analysis, there were four myocardial infarctions per 100 patients in the surveillance phase and seven per 100 patients during the intervention phase (95% confidence interval: 1-7 infarctions per 100 patients increase). For the other 10 serious adverse events there were 19 per 100 patients in the surveillance phase and 11 per 100 patients in the intervention phase (95% confidence interval: 4-11 serious adverse events per 100 patients decrease). Outreach may have led to greater detection of myocardial infarctions while reducing the incidence of other serious adverse events.

Aged↗
PubMed2004

Hyperchloraemic acidosis: another misnomer?

OBJECTIVE: To review the term hyperchloraemic acidosis. DATA SOURCES: Articles and reviews from peer reviewed journals on acid-base physiology. SUMMARY OF REVIEW: The concept of hyperchloraemic acidosis is well established in medicine and regularly taught to medical students. Unfortunately, it is yet another medical misnomer. Hyperchloraemic acidosis is only likely to exist with normal plasma sodium concentrations. This is because the acidosis is due to a decreased strong-ion-difference rather than the hyperchloraemia alone. If hyponatraemia is present, an identical acidosis can exist without hyperchloraemia; or if hypernatraemia is present there may be hyperchloraemia without acidosis. Even those who cling to the bicarbonate centred approach to acid-base physiology should recognise that describing acid-base changes in terms of chloride alone is less meaningful than considering both the strong cations and the strong anions. For those clinicians, using the Stewart approach the value of the terms "strong ion acidosis" and "strong ion alkalosis" should be readily apparent. CONCLUSIONS: The use of the term hyperchloraemic acidosis is a misnomer as the chloride ion may be elevated or depressed in the absence of an acid bade abnormality.

Journal Article↗
PubMed2002

Estimating unmeasured anions in critically ill patients: anion-gap, base-deficit, and strong-ion-gap.

We used 100 routine blood samples from critically ill patients to establish whether correcting the anion-gap and base-deficit for decreased plasma albumin improves agreement with the strong-ion-gap for estimating unmeasured anions and whether the modifications increase the proportion of samples with levels of anion-gap or base-deficit above the reference ranges. We used Bland-Altman analyses to compare the methods of estimating unmeasured ions. Compared with the strong-ion-gap, modification reduced the limits of agreement for both the anion-gap and the base-deficit. The bias for the base-deficit was also reduced but the bias for the anion-gap was increased. The proportion of samples with an anion-gap > 22 meq.l(-1) increased from 4 to 29% (p < 0.001), and the proportion with a base-deficit > 5 meq.l(-1) increased from 8 to 42% (p < 0.001). Consequently, metabolic acidosis from unmeasured ions in critically ill patients maybe more frequent than often recognised.

Acid-Base Equilibrium↗
PubMed2001

Quantitative physical chemistry analysis of acid-base disorders in critically ill patients.

Compared with the Henderson-Hasselbalch approach, the Stewart approach may better describe the mechanisms of acid-base physiology and disorders. We prospectively examined the acid-base disorders of 100 routine blood samples from critically ill patients using Stewart's physical chemistry analysis. The median results were pH 7.45, PaCO2 5.5 kPa, bicarbonate 27.2 mmol.l-1 and base excess 3 mmol.l-1. The median reference strong ion difference was 46.0 meq.l-1 and the measured median was 45.5 meq.l-1. The median reference total weak-acid concentration was 11.1 mmol.l-1. The measured median total weak-acid concentration was 6.8 mmol.l-1. From Stewart's approach, the most likely explanation for the overall alkalosis was decreased total weak-acid concentration resulting from decreased plasma albumin concentration.

Acid-Base Imbalance↗
PubMed2001

Changes in plasma creatinine concentration after cardiac anesthesia with isoflurane, propofol, or sevoflurane: a randomized clinical trial.

BACKGROUND: Renal impairment often follows cardiac surgery. The authors investigated whether sevoflurane produces greater increases in plasma creatinine concentration than isoflurane or propofol after elective coronary artery surgery. METHODS: As part of maintenance anesthesia, including during cardiopulmonary bypass, patients were randomly allocated to receive one of three agents: isoflurane (n = 118), sevoflurane (n = 118), or propofol (n = 118). Fresh gas flows were 3 l/min. The preoperative plasma creatinine concentration was subtracted from the highest creatinine concentration in the first 3 postoperative days. A median maximum increase greater than 44 microM (0.5 mg/dl) was regarded as clinically important. Data were analyzed on an intention-to-treat basis. Subgroup analyses were performed on per-protocol patients and those with preoperative renal impairment (creatinine concentration > 130 microM [1.47 mg/dl] or urea > 7.7 mM [blood urea nitrogen, 21.6 mg/dl]). RESULTS: The differences between the groups were small, clinically unimportant, and not statistically significant for the primary analysis and subgroups. The proportions of patients with creatinine increases greater than 44 microM were 15% in the isoflurane group, 17% in the sevoflurane group, and 11% in the propofol group (P = 0.45). The median increases were 8 microM in the isoflurane group, 4 microM in the sevoflurane group, and 6 microM in the propofol group. The differences between the three median maximum increases were 1-4 microM (P > 0.45). In the subgroup with preoperative renal impairment, the median increases were 10 microM in the isoflurane group, 15 microM in the sevoflurane group, and 5 microM in the propofol group (P = 0.72). CONCLUSIONS: Sevoflurane did not produce greater increases in creatinine than isoflurane or propofol after elective coronary artery surgery.

Aged↗
PubMed2001

Comparison of three methods to estimate plasma bicarbonate in critically ill patients: Henderson-Hasselbalch, enzymatic, and strong-ion-gap.

We have previously found poor agreement between Henderson-Hasselbalch and enzymatic methods for estimating plasma bicarbonate concentration in critically ill patients. In this study we compared these two established methods with a new method for estimating bicarbonate using the strong-ion-gap equation. The strong-ion-gap is derived from the Stewart approach to acid-base physiology. One hundred data sets were collected from records of routine daily blood samples in critically ill patients. Bland-Altman analyses were used to compare the three methods. We proposed that bias greater than +/- 1 mmol/l and limits of agreement wider than bias +/- 2 mmol/l were clinically important, Comparing the Henderson-Hasselbalch method to the enzymatic method, the bias was 2.1 mmol/l and the limits of agreement were -1.8 mmol/l to 5.9 mmol/l. Comparing the Henderson-Hasselbalch method to the strong-ion-gap method, the bias was -9.1 mmol/l and the limits of agreement were -17.1 mmol/l to -1.1 mmol/l. Comparing the enzymatic to the strong-ion-gap method, the bias was -11.2 mmol/l and the limits of agreement were -18.2 mmol/l to -4.2 mmol/l. This study found poor agreement between the two established bicarbonate assays and worse agreement between the established assays and the strong-ion-gap method. The strong-ion-gap method is currently too inaccurate for clinical application, but may have future use.

Acid-Base Imbalance↗
PubMed2000

The effect of PVC packaging on the acidity of 0.9% saline.

Intravenous fluids in polyvinyl chloride (PVC) packaging are known to be acidic. We proposed to determine the effect of PVC packaging on the pH of 0.9% saline solutions by comparing the predicted and measured pH of 0.9% saline equilibrated with atmospheric carbon dioxide and the measured pH of commercial solutions of 0.9% saline in PVC and polypropylene packaging. Calculation of pH was made from available physical chemistry constants and data. Measurement was made of the pH of 12 samples of prepared 0.9% saline equilibrated with atmospheric carbon dioxide. Comparison with the pH of seven commercial samples of saline in PVC packaging for intravenous use was undertaken. Further comparison was made between commercial samples of 0.9% saline in PVC or polypropylene packaging. The calculated pH of 0.9% saline was 5.61 at 20 degrees C. The median pH of the prepared samples was statistically significantly less acidic than the median pH of the PVC packaged samples for intravenous use: 5.47 vs 4.60, P < 0.05. The median pH of the PVC packaged saline was also statistically significantly more acidic than the pH of the polypropylene packaged saline: 4.62 vs 5.71, P < 0.05. The acidity of the intravenous solutions of 0.9% saline packaged in PVC was much greater than expected and is only partially explained by dissolved carbon dioxide. This acidity could be a result of packaging in PVC.

Acids↗
PubMed2000

Agreement between two plasma bicarbonate assays in critically ill patients.

Previous studies have suggested that measurement of plasma bicarbonate concentration using the Henderson-Hasselbalch equation may be unreliable, particularly in critically ill patients. We examined the agreement between two plasma bicarbonate concentration assays in critically ill patients. Data were collected from records of routine daily blood samples. Paired samples were taken at the same time from arterial lines. A Bland-Altman analysis was used to compare two bicarbonate assays in clinical use. The first used the Henderson-Hasselbalch equation for blood-gas machine calculations. The second used a spectrophotometric enzymatic technique. Comparing the enzymatic method to the calculated method (enzymatic minus calculated) the bias was -1.6 mmol/l (95% CI: -1.2 to -2.0 mmol/l). The limits of agreement were -5.85 mmol/l to 2.65 mmol/l. This study found poor agreement between the two bicarbonate assays. This poor agreement is clinically important but the causes are unclear. We suggest further investigation of the reliability of bicarbonate assays.

Bicarbonates↗
PubMed2000

Knowledge of cardiopulmonary resuscitation protocols and level of anaesthetic training.

Inadequate recall of resuscitation protocols has contributed to poor performance of resuscitation in simulation studies. We asked, does the level of anaesthesia training affect knowledge of cardiopulmonary resuscitation protocols? We used a questionnaire that covered the areas of basic life support, advanced adult life support and paediatric life support. The proportions of correct answers were hospital medical officers 50%, junior registrars 62%, senior registrars 84% and consultants 42%. The consultant group performed worse than all other groups for the basic life support and advanced life support questions. We suggest yearly resuscitation training for all anaesthetists and anaesthesia trainees.

Anesthesiology↗