| 1. |
- Frykholm, Peter, 1961-
(författare)
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Cerebral ischemia studied with positron emission tomography and microdialysis
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stroke is the third leading cause of morbidity and mortality in the industrialized world. Subarachnoid hemorrhage (SAH), the least common form of stroke, is one of the most demanding diseases treated in neurointensive care units. Cerebral ischemia may develop rapidly, and has a major influence on outcome.To be able to save parts of the brain that are at risk for ischemic brain damage, there is a need for reliable monitoring techniques. Understanding the pathophysiology of cerebral ischemia is a prerequisite both for the correct treatment of these diseases and for the development of new monitoring techniques and treatment modalities. The main aim of this thesis was to gain insight into the mechanisms of cerebral ischemia by studying early hemodynamic and metabolic changes with positron emission tomography and neurochemical changes with microdialysis. A secondary aim was to evaluate the potential of these techniques for detecting ischemia and predicting the degree of reversibility of ischemic changes.Early changes in cerebral blood flow (CBF) and metabolism (CMRO2) were studied with repeated positron emission tomography in an experimental model (MCAO) of transient focal ischemia, and in SAH patients. CMRO2 was superior to CBF in discriminating between tissue with irreversible damage and tissue with the potential for survival in the experimental model. A metabolic threshold of ischemia was found. Neurochemical changes in the ischemic regions were studied simultaneously with microdialysis. Extracellular concentrations of glucose, lactate, hypoxanthine, glutamate and glycerol were measured, and the lactate/pyruvate (LP) and lactate/glucose ratios were calculated. Changes in all the microdialysis parameters were related to the degree of ischemia (severe ischemia or penumbra). Especially the LP ratio and glycerol were found to be robust and specific markers of ischemia. In the patients, hemodynamic and metabolic changes were common, but diverse in the acute phase of SAH, and it was suggested that these changes may contribute to an increased vulnerability for secondary events and the development of secondary ischemic brain damage.
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| 3. |
- Kostic, Peter, 1970-, et al.
(författare)
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Specific anesthesia-induced lung volume changes from induction to emergence : a pilot study.
- 2018
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 62:3, s. 282-292
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Studies aimed at maintaining intraoperative lung volume to reduce post-operative pulmonary complications have been inconclusive because they mixed up the effect of general anesthesia and the surgical procedure. Our aims were to study: (1) lung volume during the entire course of anesthesia without the confounding effects of surgical procedures; (2) the combination of three interventions to maintain lung volume; and (3) the emergence phase with focus on the restored activation of the respiratory muscles.METHODS: Eighteen ASA I-II patients undergoing ENT surgery under general anesthesia without muscle relaxants were randomized to an intervention group, receiving lung recruitment maneuver (LRM) after induction, 7 cmH2 O positive end-expiratory pressure (PEEP) during anesthesia and continuous positive airway pressure (CPAP) during emergence with 0.4 inspired oxygen fraction (FiO2 ) or a control group, ventilated without LRM, with 0 cmH2 O PEEP, and 1.0 FiO2 during emergence without CPAP application. End-expiratory lung volume (EELV) was continuously estimated by opto-electronic plethysmography. Inspiratory and expiratory ribcage muscles electromyography was measured in a subset of seven patients.RESULTS: End-expiratory lung volume decreased after induction in both groups. It remained low in the control group and further decreased at emergence, because of active expiratory muscle contraction. In the intervention group, EELV increased after LRM and remained high after extubation.CONCLUSION: A combined intervention consisting of LRM, PEEP and CPAP during emergence may effectively maintain EELV during anesthesia and even after extubation. An unexpected finding was that the activation of the expiratory muscles may contribute to EELV reduction during the emergence phase.
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| 4. |
- Ali, Mustafa, et al.
(författare)
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Effects of caloric and nutrient content of oral fluids on gastric emptying in volunteers : a randomised crossover study
- 2024
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Ingår i: British Journal of Anaesthesia. - : Elsevier. - 0007-0912 .- 1471-6771. ; 132:2, s. 260-266
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous studies demonstrated conflicting results regarding the determinants of gastric emptying for fluids. Our aim was to compare gastric emptying times of fluids with different caloric and nutrient content.Methods: Healthy adult volunteers underwent gastric ultrasound assessment for 4 h after consuming beverages with different caloric and nutrient content using a crossover design (oat drink with 3% fat [310 kcal], mango juice [310 kcal], oat drink with 0.5% fat [185 kcal], and blackcurrant juice [175 kcal]). Gastric emptying time, gastric content volume, and the area under the curve (AUC) of gastric content volume -time profiles were calculated.Results: Eight females and eight males completed the study protocol. The mean (SD) gastric emptying times were 89 (32) min for blackcurrant juice, 127 (54) min for oat drink with 0.5% fat, 135 (36) min for mango juice, and 152 (40) min for oat drink with 3% fat. Gastric emptying times were slower for oat drink with 3% fat (P=0.007) and mango juice (P=0.025) than for blackcurrant juice. At 1 h after ingestion, gastric content volume was greater for mango juice (P=0.021) and oat drink with 3% fat (P=0.003) than for blackcurrant juice. The AUC was greater for oat drink with 3% fat than mango juice (P=0.029), oat drink with 0.5% fat (P=0.004), and blackcurrant juice (P=0.002), and for mango juice than blackcurrant juice (P=0.019).Conclusions: Caloric and nutrient content significantly affected gastric emptying times. A high-calorie fruit juice (mango) exhibited delayed emptying times compared with a low-calorie fruit juice (blackcurrant).
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| 5. |
- Andersson, Hanna, et al.
(författare)
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Gastric content assessed with gastric ultrasound in paediatric patients prescribed a light breakfast prior to general anaesthesia : A prospective observational study
- 2019
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Ingår i: Pediatric Anaesthesia. - : Wiley. - 1155-5645 .- 1460-9592. ; 29:12, s. 1173-1178
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundA light breakfast has been found to empty from the stomach within 4 hours in healthy volunteers.AimThe aim of this study was to investigate whether a light breakfast of yoghurt or gruel empties from the stomach within 4 hours, in children scheduled for general anaesthesia.MethodIn this observational cohort study, children aged 1‐6 years scheduled for elective general anaesthesia were prescribed free intake of yoghurt or gruel 4 hours prior to induction. They were subsequently examined with gastric ultrasound within 4 hours of ingestion. In case of gastric contents, the gastric antral area was measured, and gastric content volume (GCV) was calculated.ResultsTwenty children were included in the study and the ingested amount of gruel or yoghurt ranged 2.5‐25 mL kg−1. In 15 cases, the stomach was empty with juxtaposed walls and no further measurements were made. In four cases, there was fluid present in the stomach, but the calculated gastric contents were <0.5 mL kg−1. One patient had solids in the stomach, and GCV in this patient was calculated to 2.1 mL kg−1. The patient with solids present had ingested 25 mL kg−1 of gruel 4 hours prior to assessment. The planned procedure was therefore delayed 1 hour. There were no cases of pulmonary aspiration or vomiting.ConclusionA light breakfast 4 hours prior to induction may be considered, but there is need for further studies on safe limits for the volume ingested.
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| 6. |
- Andersson, Hanna, et al.
(författare)
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Introducing the 6-4-0 fasting regimen and the incidence of prolonged preoperative fasting in children
- 2018
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Ingår i: Pediatric Anaesthesia. - : Wiley. - 1155-5645 .- 1460-9592. ; 28:1, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundChildren often starve for longer than recommended by current preoperative fasting guidelines.AimsWe studied the effects of implementing a more lenient fasting regimen on the duration of clear fluid fasting, as well as the incidence of extended fasting in children.MethodsPreoperative duration of clear fluid fasting was recorded for patients scheduled for procedures in a unit applying the standard 6-4-2 fasting regimen. This group was compared with a cohort in the same unit 1year after transitioning to a 6-4-0 fasting regimen. The latter includes no limitations on clear fluid intake until the child is called to theater. A third cohort from a unit in which the 6-4-0 fasting regimen has been implemented for over a decade was also studied for comparison.ResultsPatients fasting according to the 6-4-2 fasting regimen (n=66) had a median fasting time for clear fluids of 4.0h and a 33.3% incidence of fasting more than 6h. After transitioning to the 6-4-0 fasting regimen (n=64), median duration of fasting for clear fluids decreased to 1.0h, and the incidence of fasting more than 6h decreased to 6.3%. In the second unit (n=73), median fasting time was 2.2h and the proportion of patients fasting more than 6h was 21.9%.ConclusionThe introduction and implementation of the 6-4-0 fasting regimen reduces median fluid fasting duration and the number of children subjected to extended fasting.
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| 7. |
- Andersson, Hanna, et al.
(författare)
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Preoperative fasting guidelines in pediatric anesthesia : are we ready for a change?
- 2018
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Ingår i: Current Opinion in Anaesthesiology. - 0952-7907 .- 1473-6500. ; 31:3, s. 342-348
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Forskningsöversikt (refereegranskat)abstract
- Purpose of review: Study after study shows that prolonged fasting before anesthesia is common in children. Pediatric anesthesiologists around the world are concerned that the current guidelines may be part of the problem. This review focuses on what can be done about it.Recent findings: We discuss new insights into the physiology of gastric emptying of different categories of food and drink. The evidence for negative effects of prolonged fasting occurring in spite of implementation of the current guidelines is examined. We also critically appraise the concept of a strict association between fasting time and the risk of aspiration and discuss recent studies in which children have been allowed clear fluids less than 2 h before anesthesia induction.Summary: Accumulating evidence indicates that changes of the current guidelines for preoperative fasting should be considered for children undergoing elective procedures.Video abstract: http://links.lww.com/COAN/A50
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| 8. |
- Andersson, Hanna, et al.
(författare)
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Preoperative weight loss, hypoglycaemia and ketosis in elective paediatric patients, preliminary results from a prospective observational study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundNew paediatric fasting guidelines allow free clear fluids up until one hour prior to surgery. At the paediatric anaesthesia department of Uppsala University Hospital, children are fasted six hours for solids, four hours for breast milk and are allowed free clear fluids up until called to theatre. Preoperative fasting is necessary to avoid perioperative pulmonary aspiration. However, extended fasting times have detrimental effects for fluid homeostasis and may cause hypoglycaemia and ketone bodies.AimThe aim of the current study was to investigate if preoperative weight loss, glucose level and ketone bodies were related to preoperative fasting times.MethodsPaediatric patients aged 0-72 months were included in this prospective, observational study. All children included were instructed to fast from midnight for solids, four hours for breast milk or semi-solids and from when they are called to theatre for clear fluids. Fasting times were registered, and patient weight was measured in the evening prior to surgery, and before induction. Blood glucose and ketone body levels were measured before induction. Multiple regression was used to determine how fasting time affected the outcomes weight change, blood glucose level and ketone bodies, respectively.Results43 patients were enrolled. Three children had a weight loss of more than 5 %, five children presented with blood glucose level < 3.3 mmol l-1, and 11 children presented with ketone bodies > 0.6 mmol l-1. There was no correlation between fasting time and the respective outcomes.ConclusionEven with a lenient preoperative fasting regimen, mild dehydration or hypoglycaemia may occur. This methodology may be used in further studies of the effects of preoperative fasting in settings where dehydration may be more significant.
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| 9. |
- Andersson, Hanna
(författare)
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Reduced Preoperative Fasting in Children
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Preoperative fasting is recommended in order to reduce the risk of perioperative pulmonary aspiration. However, preoperative fasting may have negative effects on patient wellbeing and homeostasis. In this thesis, more lenient regimens for preoperative fasting in elective paediatric patients were assessed, with the aim to further improve preoperative fasting regimens.Paper I investigated if paediatric patients allowed to drink clear fluids until called to surgery, had an increased risk of pulmonary aspiration. The incidence of perioperative pulmonary aspiration in children allowed free clear fluids until called to surgery was 3 in 10 000, as compared to 1-10 in 10 000 in previous studies where longer fasting intervals were studied. Hence, no increase of incidence for pulmonary aspiration was found.Paper II investigated actual fasting times for clear fluids when applying two-hour fasting for clear fluids, and zero-hour fasting for clear fluids. When applying two-hour fasting, children were fasted median four hours for clear fluids. After transitioning to zero-hour fasting, median fasting time decreased to one hour, and the incidence of children fasting for more than six hours decreased from 35 % to 6 %. Abandoning the time limit for clear fluids significantly reduced the proportion of patients fasting for extended periods.Paper III assessed gastric content volume after a light breakfast in children scheduled for elective general anaesthesia. Patients were examined with gastric ultrasound four hours after a light breakfast. Of the 20 patients included in the study, 15 had an empty stomach, 4 had clear fluids < 0.5 ml kg-1 and one had solid content in the stomach. A light breakfast preoperatively might be safe, but amount and caloric restriction is needed to avoid the risk of perioperative pulmonary aspiration.Paper IV investigated preoperative weight loss, glucose level and ketone bodies in paediatric patients presenting for elective surgery. The outcomes were tested for correlation to preoperative fasting times. Of the 43 children enrolled in the study, three had weight loss of more than 5 %, five children presented with blood glucose level < 3.3 mmol l-1, and 11 children presented with ketone bodies > 0.6 mmol l-1. There was no correlation between fasting time, and the respective outcomes. Even with a lenient fasting regimen, there is risk of mild preoperative dehydration, hypoglycaemia and ketogenesis.In conclusion, the results obtained in the present thesis supports the shift to more lenient preoperative fasting regimens for clear fluids in elective paediatric patients.
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| 10. |
- Blacker, C, et al.
(författare)
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Randomized cross-over study investigating the tolerability and side effects of an intra-oral air-cooling device compared to ice in healthy volunteers
- 2023
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Ingår i: Medical Oncology. - : Springer. - 1357-0560 .- 1559-131X. ; 40
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Tidskriftsartikel (refereegranskat)abstract
- Oral cryotherapy (OC) is a common preventive treatment of oral mucositis (OM) and is recommended in international guidelines. Ice and air OC have previously been shown to result in temperature reductions of 8.1-12.9 degrees C, and 14.5 degrees C, respectively, in healthy volunteers. However, no direct comparison between these two modalities has been performed. The primary aim was to investigate the tolerability and side effects of air OC using an intra-oral air-cooling (IOAC) device compared with ice OC. The secondary aim was to evaluate the temperature reduction in the mouth for the two respective methods. Cross-over study with randomization to order of treatment, in 15 healthy volunteers. We evaluated the self-reported intensity, frequency, and discomfort for 13 pre-defined side effects used in previous studies. All participants were able to complete both OC sessions, although one participant required reduced airflow in the air OC arm. The subjects reported more discomfort from being cold, having sensitive teeth, and numbness in the ice OC group, while they reported more discomfort from swallowing when subjected to air OC. No significant difference in the median temperature reduction was detected in the two modalities, except for the dorsal posterior part of the tongue where temperature reduction was larger in the ice OC group. We found that oral cooling using a new IOAC device was tolerated and seems to be safe in healthy volunteers.
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