Wann-Cherng Perng

Effects of Implementing Adaptive Support Ventilation in a Medical Intensive Care Unit

BACKGROUND: Adaptive support ventilation (ASV) facilitates ventilator liberation in postoperative patients in surgical intensive care units (ICU). Whether ASV has similar benefits in patients with acute respiratory failure is unclear. METHODS: We conducted a pilot study in a medical ICU that manages approximately 600 mechanically ventilated patients a year. The ICU has one respiratory therapist who manages ventilators twice during the day shift (8:00 am to 5:00 pm). No on-site respiratory therapist was present at night. We prospectively enrolled 79 patients mechanically ventilated for ≥ 24 hours on pressure support of ≥ 15 cm H2O, with or without synchronized intermittent mandatory ventilation, FIO2 ≤ 50%, and PEEP ≤ 8 cm H2O. We switched the ventilation mode to ASV starting at a “%MinVol” setting of 80–100%. We defined spontaneous breathing trial (SBT) readiness as a frequency/tidal-volume ratio of < 105 (breaths/min)/L on pressure support of ≤ 8 cm H2O and PEEP of ≤ 5 cm H2O for at least 2 h, and all spontaneous breaths. The T-piece SBT was considered successful if the frequency/tidal-volume ratio remained below 105 (breaths/min)/L for 30 min, and we extubated after successful SBT. The control group consisted of 70 patients managed with conventional ventilation modes and a ventilator protocol during a 6-month period immediately before the ASV study period. RESULTS: Extubation was attempted in 73% of the patients in the ASV group, and 80% of the patients in the non-ASV group. The re-intubation rates in the ASV and non-ASV groups were 5% and 7%, respectively. In the ASV group, 20% of the patients achieved extubation readiness within 1 day, compared to 4% in the non-ASV group (P = <.001). The median time from the enrollment to extubation readiness was 1 day for the ASV group and 3 days for the non-ASV group (P = .055). Patients switched to ASV were more likely to be liberated from mechanical ventilation at 3 weeks (P = .04). Multiple logistic regression analysis showed that, of the independent factors in the model, only ASV was associated with shorter time to extubation readiness (P = .048 via likelihood ratio test). CONCLUSIONS: Extubation readiness may not be recognized in a timely manner in at least 15% of patients recovering from respiratory failure. ASV helps to identify these patients and may improve their weaning outcomes.

Protective agents used as additives in University of Wisconsin solution to promote protection against ischaemia-reperfusion injury in rat lung

1. An intervention to reduce ischaemia-reperfusion lung injury will be an important advance in transplant medicine. Although the mechanisms associated with producing ischaemia-reperfusion endothelial injury have not been completely elucidated, many of the injury mediators have been studied in detail. While no single pharmacological therapy is likely to be totally effective in eliminating this complex injury, we have developed a mixture of agents that are known to block pathways involved in producing ischaemia-reperfusion-associated lung vascular injury.2. The present study modified University of Wisconsin solution (UW) by adding one of the protective agents prostaglandin E1 (PGE1), dexamethasone (Dex) or dibutyryl cAMP (Bt2-cAMP), or a combination of these, to the perfusate of rat lungs exposed to 4 h of cold ischaemia followed by 1 h of reperfusion. Nine modified UW solutions were studied: (1) UW+Dex, (2) UW+PGE1, (3) UW+Bt2-cAMP, (4) UW+Dexx3, (5) UW+PGE1x3, (6) UW+Bt2-cAMPx3, (7) UW+Dex+PGE1, (8) UW+Dex+Bt2-cAMP, (9) UW+PGE1+Bt2-cAMP. These solutions were utilized in individual experiments to assess haemodynamic changes, lung weight gain, the capillary filtration coefficient (Kfc) and pathology in all lungs.3. The results indicate that lung weight gain and Kfc values were significantly lower than with UW alone in groups 1, 2 and 3, which contained only one additional protective agent. In groups 4, 5 and 6, which contain three times the concentration of each protective agent, both Kfc and lung weight gain were similar to those measured in groups 1, 2 and 3, i.e. lungs were protected but the protection was not dose dependent. In groups 7, 8 and 9, which contained two protective agents, lung weight gain and Kfc were greatly reduced compared with UW alone. Histopathological studies showed similar decreases in the injury profiles of lungs.4. Although UW contains several antioxidant protective agents such as allopurinol and glutathione, it did not provide effective protection in our ischaemia-reperfusion lung injury model. UW modified with an additive of PGE1, Dex or Bt2-cAMP attenuated ischaemia-reperfusion injury. Furthermore, UW containing two of these protective agents augmented the protection. Among the modified solutions, it appears that UW+PGE1+Bt2-cAMP protects the lungs to a greater extent than all other solutions used in our study. We suggest that preservation solutions containing PGE1-Bt2-cAMP will provide additional protective effects to organs stored for transplantation.

Hyperbaric oxygen attenuates cell growth in skin fibroblasts cultured in a high-glucose medium

Hyperglycemia and hypoxia synergistically retard diabetic wound healing. We investigated the direct effect of hyperbaric and normobaric hyperoxia on skin fibroblasts cultured in a high‐glucose medium. Detroit 551 human dermal fibroblasts cultured in Dulbeccos modified Eagles medium containing d‐glucose had reduced cell survival compared with cells grown in normal glucose medium; survival was 27.5±3.8% lower in 25u2003mM glucose and 30.6±3.7% lower in 50u2003mM glucose. Cell survival decreased because of inhibition of cell proliferation and enhanced cell death. Daily hyperbaric oxygen therapy at 2.5 atmosphere absolute for 90 minutes on 3 consecutive days reduced cell proliferation and increased cell death in normal cultured fibroblasts. Hyperbaric oxygen therapy and high‐glucose medium had a synergistic effect and reduced survival by 37.6±4.4% (25u2003mM glucose) and 39.6±5.1% (50u2003mM glucose). The effects of hyperbaric oxygen and high‐glucose medium were associated with overproduction of reactive oxygen species. Our results suggest that direct exposure of skin fibroblasts to hyperbaric oxygen affects cell growth and superimposes the toxic effect of high glucose. This cytotoxicity may be related to the production of reactive oxygen species in the fibroblasts.

Ethnicity relation to anomalous systemic arterial supply to normal basal segments of the left lower lobe

A 24-year-old female with an anomalous systemic arterial (ASA) supply to normal basal segments of the left lower lobe (LLL) has been suffering from occasional hemoptysis for the last 4.5 years. Our hospital has been following her up for the last 2.5 years. In the first chest radiograph, an unobvious retrocardiac hazy nodule was shown. The following chest computed tomography scan performed indicated clearly this anomaly. According to our analysis of similar reported cases in the English medical literature, the statistics suggest a close relation between Asian population and this anomaly. Therefore, ASA supply to normal basal segments of the LLL should be put into consideration when examining an Asian patient with symptoms of hemoptysis or exertional dyspnea but showing no obvious image findings in chest radiographs.

Thalidomide reduces lipopolysaccharide/zymosan-induced acute lung injury in rats

Pharmacological therapies targeting fulminant lung inflammation in acute lung injury (ALI) need to be improved. We evaluated the effect of thalidomide, a chemical modulating both acute and chronic inflammation, on ALI induced by intravenous administration of lipopolysaccharide (LPS) and zymosan in male Sprague-Dawley rats. Injection of LPS and zymosan induced significant lung inflammation, as evidenced by increased neutrophil sequestration in lung tissue as well as enhanced nitric oxide metabolite (NOx–) production in the serum and bronchoalveolar lavage (BAL) fluid. Lactate dehydrogenase (LDH) activity and protein concentration in BAL fluid were significantly increased after administration of LPS and zymosan. Pulmonary microvascular permeability was determined using the Evans blue retention method, which showed a significant increase in microvascular permeability after LPS and zymosan administration, indicating the development of ALI. Animals that received thalidomide (100 mg/kg) 2 h prior to LPS injection had significantly reduced pulmonary NOx– production, pulmonary microvascular permeability, and LDH activity and protein concentration in BAL fluid. We therefore conclude that thalidomide ameliorates lung inflammation and reduces ALI induced by combined LPS and zymosan administration in rats.

The Protective Effect of Adenosine Triphosphate-MgCl2 on Ischemia-Reperfusion Lung Injury Is Leukocyte Dependent

Adenosine triphosphate (ATP)-MgCl(2) attenuates ischemia-reperfusion (I-R)-induced lung injury in rats. A previous study indirectly suggests that Mg(2+)-dependent ecto-ATPases on the surface of leukocytes are responsible for the hydrolysis of ATP-MgCl(2) to adenosine, which then contributes to the protective effect of ATP-MgCl(2). This study investigated the role of leukocytes in I-R injury and the protective effect of ATP-MgCl(2) in our buffer-perfused isolated rat lung model. After isolating the lung blood flow of adult male Sprague-Dawley rats, the lungs were perfused through the pulmonary artery cannula with a physiologic salt solution containing human serum albumin. The protective effect of ATP-MgCl(2) pretreatment with or without leukocytes was investigated. Capillary permeability (K(fc)), lung weight gain (LWG), lung wet weight/body weight ratio (LW/BW), lung lavage protein concentration (LPC) and pulmonary artery pressure (PAP) were measured. I-R produced a significant increase in K(fc), LWG, LW/BW, LPC, and PAP. The increases in these indices were significantly attenuated by pretreatment with ATP-MgCl(2) (1 x 10(-6)M) together with leukocytes (2.9 x 10(6)/ml in the perfusate) but not with ATP-MgCl(2) alone. Our data suggest that I-R-induced acute lung injury is not dependent on circulating leukocytes. Pretreatment with ATP-MgCl(2) plus leukocytes but not ATP-MgCl(2) alone had protective effects against I-R lung injury. Whether these findings occur in vivo could not be determined in this study. In our isolated lung red blood cell-free perfusate system, the protective effect of ATP-MgCl(2) requires the presence of leukocytes.

A case of Adenocarcinoma of the Lung Associated with Sarcoidosis

Sarcoidosis, a systemic granulomatous disease of undetermined etiology, is characterized by variable clinical presentation and course. Although sarcoidosis and lung cancer are both frequently encountered pulmonary diseases, their simultaneous occurrence in the same patient is unusual. The causal relationship between the two diseases remains unclear, and the concurrence can cause a diagnostic dilemma and make preoperative staging diffi cult. We report a case of concurrent sarcoidosis with lung cancer who was initially diagnosed with pulmonary sarcoidosis.

Sonographic Septation as One Predictor for Pleural Drainage in Patients with Non-purulent Parapneumonic Effusions

Background: The American College of Chest Physician (ACCP) has identified 4 categories of parapneumonic effusion (PPE) to guide treatment. The modality in assessing anatomy of pleural fluid is not well-defined, making differentiation of category 2 from category 3 PPE difficult. We investigated whether sonographic septation predicts category 3 PPE in guiding early pleural drainage. Methods: Medical records of patients with lung abscess or pneumonia at admission were reviewed retrospectively. All patients had a plain chest radiograph upon admission. Patients classified as AACP category 2 or 3 who underwent chest sonography with thoracentesis revealing non-purulent parapneumonic effusions with neutrophils predominance were included. Inter-observer variations in determining PPE category were analyzed. Further, positive predictive value (PPV), relative risk (RR) and reading agreement of positive sonographic septation in predicting category 3 PPE were determined. Results: 51 patients of the total 97 recruited had sonographic septation. The reading agreement between thoracic radiologists in determining the category of pleural fluid by plain chest radiograph was low with a kappa coefficient (κ) of 0.29. In contrast, reading agreement of positive sonographic septation was substantial (κ = 0.73). A signifi cantly higher PPV for category 3 effusion was observed in patients with sonographic septation (86.3%) compared to those with no septation (43.5%) (p ＜ 0.001). The RR of category 3 PPE with sonographic septation was 1.98 (95% CI: 1.40-2.81; p＜0.001). Conclusions: Sonographic septation is a useful sign in predicting category 3 PPE, and may in conjunction with plain chest radiograph, enable a more accurate diagnosis or screening way of patients with lung abscess and pneumonia.

Extracorporeal Membrane Oxygenation for Management of Carbon Monoxide Intoxication

Emergency use of extracorporeal membrane oxygenation (ECMO) for cardiopulmonary failure is well documented. However, the use of ECMO for carbon monoxide (CO) poisoning is rare. We report a case of a patient with severe CO poisoning that initially manifested as stunned myocardium-induced acute pulmonary edema. The patient was severely hypoxemic and refractory to mechanical ventilation at 7 hours after hospitalization. We applied veno-arterial ECMO for rescue life support for 3 days. The patient had a dramatic full recovery without immediate neurologic sequelae for the 3-day period. Under ECMO support, PaO2 increased from 34.8 to 299.9 mmHg, and ventilator FiO2 decreased to 0.4 within 3 days. The patients consciousness also improved, with the Glasgow Coma Scale (GCS) score increasing from 8 to 15. Although the standard treatment for CO poisoning remains controversial, an aggressive rescue strategy is warranted for concurrent cardiovascular collapse and acute respiratory failure after severe CO poisoning in order to reduce the mortality of a reversible etiology.

Breast Metastasis from Lung Adenocarcinoma in a 26-year-old Woman: A Case Report

Metastatic breast adenocarcinoma of pulmonary origin is extremely rare. Herein, we present an incidental finding of mammary nodules in a 26-year-old female during the work-up for metastatic brain tumors. Sono-guided fine-needle aspiration cytology of the breast nodules and CT-guided needle biopsy of the pulmonary mass were performed. The morphologic features and immunoreactivity to thyroid transcription factor-1 (TTF-1) confirmed this diagnosis. The patient received treatment and the clinical condition improved gradually. It is crucial to accurately distinguish primary breast cancer from a metastasized cancer because both the treatment and the outcome will differ.