Quantitative assessment of atelectasis formation under high frequency jet ventilation during liver tumour ablation-A computer tomography study.

BACKGROUND: High frequency jet ventilation (HFJV) can be used to minimise sub-diaphragmal organ displacements. Treated patients are in a supine position, under general anaesthesia and fully muscle relaxed. These are factors that are known to contribute to the formation of atelectasis. The HFJV-catheter is inserted freely inside the endotracheal tube and the system is therefore open to atmospheric pressure. AIM: The aim of this study was to assess the formation of atelectasis over time during HFJV in patients undergoing liver tumour ablation under general anaesthesia. METHOD: In this observational study twenty-five patients were studied. Repeated computed tomography (CT) scans were taken at the start of HFJV and every 15 minutes thereafter up until 45 minutes. From the CT images, four lung compartments were defined: hyperinflated, normoinflated, poorly inflated and atelectatic areas. The extension of each lung compartment was expressed as a percentage of the total lung area. RESULT: Atelectasis at 30 minutes, 7.9% (SD 3.5, p = 0.002) and at 45 minutes 8,1% (SD 5.2, p = 0.024), was significantly higher compared to baseline 5.6% (SD 2.5). The amount of normoinflated lung volumes were unchanged over the period studied. Only a few minor perioperative respiratory adverse events were noted. CONCLUSION: Atelectasis during HFJV in stereotactic liver tumour ablation increased over the first 45 minutes but tended to stabilise with no impact on normoinflated lung volume. Using HFJV during stereotactic liver ablation is safe regarding formation of atelectasis.

Post-operative hypertension during early recovery following liver tumour ablation: A retrospective study.

BACKGROUND: High-frequency jet ventilation is necessary to reduce organ movements during stereotactic liver ablation. However, post-operative hypertensive episodes especially following irreversible electroporation ablation compared with microwave ablation initiated this study. The hypothesis was that hypertensive episodes could be related to ventilation or ablation method. METHODS: The aim of this retrospective study was to assess the proportion of patients with hypertensive events during recovery following liver ablation under general anaesthesia and to analyse the relation to ventilation and ablation technique. A medical chart review of 134 patients undergoing either high-frequency jet ventilation and microwave ablation (n = 45), high-frequency jet ventilation and irreversible electroporation (n = 44), or conventional ventilation and microwave ablation (n = 45) was performed. The proportion of patients with at least one episode of systolic arterial pressure 140-160, 160-180 or >180 mmHg during early recovery and the impact of ventilation method was studied. RESULTS: Out of 134 patients, 100, 75 and 34 patients had at least one episode of mild, moderate and severe hypertension. Microwave ablation, as well as high frequency jet ventilation, was associated with an increased odds ratio for post-operative hypertension. The proportion of patients with at least one severe hypertensive event was 18/45, 9/44 and 7/45, respectively. CONCLUSION: Both ventilation and ablation technique had an impact on post-operative hypertensive episodes. The microwave ablation/high-frequency jet ventilation combination increased the risk as compared with irreversible electroporation/high-frequency jet ventilation and microwave ablation/conventional ventilation.

High Frequency Jet Ventilation during stereotactic ablation of liver tumours: an observational study on blood gas analysis as a measure of lung function during general anaesthesia.

Background: Stereotactic ablation of tumours in solid organs is a promising curative procedure in clinical oncology. The technique demands minimal target organ movements to optimise tumour destruction and prevent injury to surrounding tissues. High frequency jet ventilation (HFJV) is a novel option during these procedures, reducing the respiratory-associated movements of the liver. The effects of HFJV via endotracheal catheter on gas exchange during liver tumour ablation is not well studied. Methods: The aim of this explorative study was to assess lung function and the effects on blood gas and lactate during HFJV in patients undergoing stereotactic liver ablation. Blood gases were analysed in 25 patients scheduled for stereotactic liver ablation under general anaesthesia pre-induction, every 15 minutes during HFJV and following extubation in the recovery room. The HFJV was set at fixed settings. Results: None of the patients developed hypoxia or signs of increased lactate production but a great variation in PaO 2/FiO 2 ratio was found; from 13.1 to 71.3. An increase in mean PaCO 2 was observed, from a baseline of 5.0 to a peak of 7.1 at 30 minutes (p <0.001) and a decrease was found in median pH, from a baseline of 7.44 to 7.31 at 15 minutes (p=0.03). We could not see any clear association between a decrease in PaO 2/FiO 2 ratio and PaCO 2 elevation. Conclusions: HFJV during general anaesthesia in patients undergoing stereotactic liver ablation is feasible and it did not cause hypoxemia or signs of increased lactate production. A reversible mild to moderate impairment of gas exchange was found during HFJV.

[Tracheal injury is a rare but potentially critical complication to intubation]. / Trakealskada vid intubationsanestesi ­ sällsynt komplikation - Kräver akut handläggning, kan vara livshotande.

Tracheal rupture is a rare but potentially lethal injury. There are several causes; traumatic, neck surgery, tracheal dilatation and association to intubation. We describe a case of tracheal injury where the patient developed subcutaneous emphysema while coughing in the recovery room. Our patient did initially not complain of any breathing difficulties but after further coughing the emphysema increased and the patient became dyspnoeic. Emergent CT-imaging showed a tracheal injury and our patient was transport to ENT for stent therapy. It is important to recall the risk for tracheal injury. Subcutaneous emphysema and breathing difficulties with debut following extubation should raise the suspicion.

1000 consecutive ablation sessions in the era of computer assisted image guidance - Lessons learned.

BACKGROUND: Ablation therapies for tumours are becoming more used as ablation modalities evolve and targeting solutions are getting better. There is an increasing body of long-term results challenging resection and proving lower morbidities and costs. The aim of this paper is to share the experiences from a high-volume centre in introducing computer assisted targeting solutions and efficient ablation modalities like microwave generators and irreversible electroporation. MATERIAL AND METHODS: One thousand consecutive treatments in one high-volume centre were evaluated retrospectively from prospectively collected data. RESULTS: The purpose of this paper is to present the benefits of going into computer assisted targeting techniques and microwave technology; pitfalls and overview of outcomes. The main target organ was the liver and the main indications were ablation of hepatocellular carcinomas and colorectal liver metastases. With the assistance of computer assisted targeting the local recurrence rate within 6 months has dropped from 30 to near 10%. The survival of patients with hepatocellular carcinoma and colorectal liver metastases is not worse if the tumour can be retreated after a local recurrence. Multiple colorectal liver metastases can be treated successfully. DISCUSSION: The incorporation of computer assisted targeting technologies for ultrasound-, ct guided- and laparoscopic tumour ablation has been very successful and without a noticeable learning curve. The same is true for switching from radiofrequency energies to microwave generators and irreversible electroporation. CONCLUSION: It is well worthwhile upgrading ablation and targeting technologies to achieve excellent and reproducible results and minimizing operator dependency.

Clinical application of high frequency jet ventilation in stereotactic liver ablations - a methodological study.

Background: Computer-assisted navigation during thermal ablation of liver tumours, may help to correct needle placement and improve ablation efficacy in percutaneous, laparoscopic and open interventions. The potential advantage of using high frequency jet-ventilation technique (HFJV) during the procedure is by minimising the amplitude of respiration-related upper-abdominal organs movements. The aim of this clinical methodological trial was to establish whether HFJV would give less ventilatory induced liver movements than conventional ventilation, during stereotactic navigated ablation of liver metastases under open surgery. Methods: Five consecutive patients scheduled for elective, open liver ablation under general propofol and remifentanil anaesthesia were included in the study protocol. During the stereotactic targeting of the tumours, HFJV was chosen for intraoperative lung ventilation. For tracking of liver movement, a rigid marker shield was placed on the liver surface and tracked with an optical position measurement system. A 4D position of the marker shield was measured for HFJV and conventional tidal volume lung ventilation (TV). At each time point the magnitude of liver displacement was calculated as an Euclidean distance between translational component of the marker shield's 3D position and previously estimated centroid of the translational motion. Results: The mean Euclidean liver displacement was 0.80 (0.10) mm for HFJV and 2,90 (1.03) mm for TV with maximum displacement going as far as 12 mm on standard ventilation (p=0.0001). Conclusion: HFJV is a valuable lung ventilation method for patients undergoing stereotactic surgical procedures in general anaesthesia when reduction of organ displacement is crucial.

The use of high-frequency ventilation during general anaesthesia: an update.

Various forms of high-frequency ventilation (HFV) have been described. HFV is broadly defined as artificial ventilation of the lungs with sub-deadspace tidal volumes delivered using supra-physiological frequencies. HFV has been used in anaesthesia and intensive care for special procedures and conditions since the 1960s. Clinical interest in the use and the technical evolution of HFV has developed over time. There is a renewed interest in HFV for avoiding parenchymal movement during stereotactic tumour ablation. The present paper aims to give an overview of the fundamental physiology, technical aspects, and clinical challenges of HFV in ablation procedures during general anaesthesia, where HFV is used to minimise the movements of the ablation target.

[Iron intoxication--poisoning with easily accessible medicines]. / Järnintoxikation - förgiftning med läittillgängligt läkemedel.

A 20-year-old woman was found semiconscious on the floor in a pool of black diarrhea with an empty 100 jar of ferrous sulphate beside her (100 mg Fe2+/tablet), 160 mg/kg. She was brought to the hospital an estimated 4 hours after ingestion and presented with irritability and a fluctuating CNS depression. Her blood pressure was 190/85 mmHg and pulse 130 bpm. An arterial blood gas analysis showed pH 7.17, pCO2 5.4 kPa, pO2 16.7 kPa and BE ­14 mmol/l. Deferoxamine was started immediately with a dose of 15 mg/kg/h intravenously. The patient was intubated in the ICU and whole bowel irrigation was performed. Due to technical problems with the venous blood sampling, a correct measurement of the serum iron concentration (s-Fe2) was not at hand until 15 hours post ingestion and showed 131 µmol/l. At that point her condition deteriorated with circulatory instability, hepatic failure, coagulopathy and renal insufficiency. Despite full treatment including continuous renal replacement therapy she died after 4 Days.