Burning intensity and low light availability reduce resprouting ability and vigor of Buxus sempervirens L. after clearing.

Thinning and prescribed burning are two common operations for reducing fuel accumulation and decreasing the intensity and severity of wildfires. However, the resprouting response of understory species may reduce the effectiveness of fuel load treatments and thus negatively affect the cost-benefit ratio of these treatments. This study focuses on Buxus sempervirens, a slow-growing, multi-stemmed tree species, frequently dominant in the understory of temperate European forests, which resprouts strongly after clearing or burning. The aim was to assess how light availability and burning influence resprouting ability (resprouting or not) and vigor (i.e. the growth of resprouts) after clearing B. sempervirens in thinned stands without slash removal (unburned) or with burning of slash residues (burned), two years after the treatments. All individuals studied resprouted shortly after clearing in unburned stands, whereas almost ca. 40% never resprouted in the burned stands. Fire intensity, measured at the base of 49 individuals, contributed to explaining the likelihood of mortality. The number of resprouts was directly influenced by the pre-treatment size of individuals, but this relationship was lower in burned stands. Fire intensity, recorded in 29 resprouted individuals, also influenced the number of resprouts. Post-treatment light availability, in addition to pre-treatment size, contributed to explaining the volume of the ten largest resprouts and the length of the largest resprout. No tradeoffs between the resprout number and the volume of the ten largest resprouts or the maximum resprout length were found. Our study suggests that burning after clearing reduces the resprouting ability of B. sempervirens. Moreover, avoiding affecting the canopy cover reduces its resprouting vigor and, consequently, increases the effectiveness of understory fuel load treatments.

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[The incidence of intraoperative conciousness in emergency surgery and its possible relation to the post-traumatic stress syndrome. Presentation of three cases]. / Incidencia de conciencia intraoperatoria en cirugía urgente y su posible relación con el síndrome de estrés postraumático. A propósito de tres casos.

Intraoperative awakening and recall of specific events is a rare complication (0.2 to 1.3%) of surgery. The possibility of developing serious psychiatric complications, such as posttraumatic stress disorder (PTSD) makes the prevention and detection of intraoperative awareness a subject of special interest. We describe our experience with three patients in whom awareness was detected during emergency surgery under general anesthesia. We conducted two structured interviews with the patients three months after surgery in order to detect the possible development of psychiatric complications. One patient suffered insomnia and reexperience of the event during the first two weeks after surgery. Improvement was spontaneous. None of the patients suffered PTSD. Efforts to decrease the incidence of episodes of intraoperative awakening with specific recall must be based on clinical observation and exhaustive monitoring of the patient, including anesthetic gases, given that no ideal method of monitoring depth of anesthesia exists. Cases should be detected in the first few days after surgery by means of a specific test. Likewise, possible causes for the episode should be explained to the patient, who should be followed for six months so that early diagnosis of PTSD or other psychiatric complications can be made.

[Prevention of cross contamination, patient to anesthesia apparatus to patient, using filters]. / Profilaxis de la contaminación cruzada, enfermo-aparato de anestesia-enfermo, mediante filtros.

Concern for cross infections from patient to patient via apparatus is particularly relevant today. There are several ways to prevent patient contamination through anesthetic devices. Although there is no clinical evidence for using one alternative over another and each hospital establishes its own hygienic protocols, we have introduced the systematic use of filters with patients undergoing general anesthesia. We describe the features of filters available on the market and our protocol for their use. The efficacy of a filter depends on whether bacteria or viruses are to be controlled. Filters can be classified into three groups or generations based on mesh quality: 1) heat and humidity exchangers (HHE), with large mesh screens that allow water to pass through; 2) bacterial filters (FHHE), with finer mesh that is permeable to droplets of water and 3) folded membrane filters (FHHE) that are hydrophobic, with very fine mesh that stops water. We describe three basic physical tests (passage of water, passage of smoke and increase of resistance when applied to the patient) for filters to be classified. The ideal filter is hydrophobic and does not increase circuit resistance over the amount specified. Four principles are emphasized in the protocol: 1) the filter forms a part of the patient, not the apparatus; 2) proper placement of the filter is between the patient and the circuit's "Y" piece; 3) the main purpose of the filter is to prevent contamination of the apparatus, and 4) if a hydrophobic filter is used with each patient, the use of a disposable respiratory circuit is not called for.

[Efficacy of topical administration of lidocaine through a Malinckrodt Hi-Lo Jet tube in lessening cough during recovery from general anesthesia]. / La eficacia de la administración tópica de lidocaína a través del tubo Malinckrodt Hi-Lo Jet para atenuar la tos en el despertar de la anestesia general.

To achieve tracheal anesthesia during intubation, an endotracheal tube was purposely designed. The tube had multiple laser-induced perforations in its lower portion produced that allowed administration of the local anesthetic in a pulverized form. We evaluated the efficacy of lidocaine 2% in preventing cough during recovery from general anesthesia. The goal of this study was to perform a topical anesthesia of the hypopharynx, larynx, and trachea. This attenuates the laryngeal reflex occurring during anesthesia recovery and therefore, prevents from potential complications. Sixteen patients ASA I-II underwent surgery with general anesthesia. They were prospectively studied following a randomized double blind protocol. The control group received saline infusion (n = 6) whereas the experimental group (n = 10) was treated with lidocaine. At the end of the anesthesia period, the presence of cough was treated with the test solution. In 90% of cases treated with lidocaine, cough disappeared in about 30 seconds and patients tolerated the endotracheal tube until extubation was performed. All patients who received saline solution presented cough until extubation.

[Usefulness of pulse oximetry in thoracic surgery]. / Utilidad de la pulsioximetría en cirugía torácica.

Saturation of hemoglobin in arterial blood was simultaneously measured by co-oximetry (SaO2) and by pulse oximetry (SpO2) in 228 samples from 42 patients undergoing general anesthesia for thoracic surgery. Data was referred to SaO2 obtained with arterial catheterization. We found a significant correlation (r: 0.949 and p less than 0.001) and the mean differences were 0.77 +/- 1.84. The correlation between PaO2 and the difference among both methods was significantly negative (r: -0.20; p less than 0.001). Although there was a significant correlation, the method loses reliability and accuracy in patients with hypoxemia. In these patients oximetric values are slightly lower than those obtained with arterial cannulation. We emphasize the clinical usefulness of this technique since it is instantaneous and allowed immediate therapeutic actions.