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Mar del Plata, Argentina

Tusman G.,Hospital Privado de Comunidad | Belda J.F.,Hospital Universitario La Paz
Current Anaesthesia and Critical Care

General anesthesia causes atelectasis and airway closure in dependent areas of the lung. Both kinds of collapse induce a deterioration of gas exchange characterized by a decrease in arterial oxygenation and an increase in dead space. The severity of this lung dysfunction is proportional to the amount of collapsed tissue that depends on anesthesia, surgical and patient's factors.Lung collapse can be partially prevented by decreasing FiO2 and/or by applying CPAP during the induction of anesthesia. However, only lung recruitment maneuvers can resolve atelectasis completely. These recruitment maneuvers are ventilatory strategies aimed to restore the normal aeration of the lungs. The maneuvers consist in a brief and controlled increase in airway pressure to open up those pulmonary areas with collapse. Afterward, the lungs are ventilated with a protective strategy setting keeping the lungs open in time with enough positive-end expiratory pressure and low driving pressure. This article describes the physiological and clinical background of lung recruitment maneuvers applied during the intra-operative period. © 2010 Elsevier Ltd. Source

Tusman G.,Hospital Privado de Comunidad | Bohm S.H.,Swisstom AG | Warner D.O.,Rochester College | Sprung J.,Rochester College
Current Opinion in Anaesthesiology

PURPOSE OF REVIEW: This review evaluates the link between perioperative lung atelectasis and postoperative pulmonary complications (PPCs) and how appropriate ventilatory strategies could mitigate this problem. RECENT FINDINGS: Atelectasis may contribute to serious PPCs including respiratory failure and pneumonia. Ventilator settings during anesthesia, especially with higher tidal volumes (V T) (>10 ml/kg), high plateau pressures (>30 cmH 2O) and without positive end expiratory pressure (PEEP), are associated with lung injury even in healthy, but partially collapsed, lungs. These injurious settings may cause inflammation which is related to repetitive tidal recruitment and alveolar overdistension. Such ventilator-induced lung injury can be attenuated by using low V T and plateau pressures at sufficient PEEP, ideally after actively recruiting the lungs. The use of continuous positive airway pressure and 'lower' FiO 2 during anesthetic induction, intraoperative use of lower FiO 2, low V T, lung recruitment and PEEP ('protective ventilatory strategy') in conjunction with postoperative early mobilization, breathing exercises and continuous positive airway pressure may help in maintaining lung aeration, thereby decreasing hypoxemia and risk of postoperative pneumonia. Evidence is accumulating suggesting that the incidence of postoperative pulmonary complication could be markedly reduced if an 'open lung' philosophy was adopted for the perioperative care. SUMMARY: A goal-directed ventilatory approach keeping an 'open lung' condition during the perioperative period may reduce the incidence of PPCs. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source

Tusman G.,Hospital Privado de Comunidad
Anesthesia and Analgesia

Pulse oximetry is an undisputable standard of care in clinical monitoring. It combines a spectrometer to detect hypoxemia with a plethysmograph for the diagnosis, monitoring, and follow-up of cardiovascular diseases. These pulse oximetry capabilities are extremely useful for assessing the respiratory and circulatory status and for monitoring of mechanically ventilated patients. On the one hand, the key spectrography-derived function of pulse oximetry is to evaluate a patient’s gas exchange that results from a particular ventilatory treatment by continuously and noninvasively measuring arterial hemoglobin saturation (SpO2). This information helps to maintain patients above the hypoxemic levels, leading to appropriate ventilator settings and inspired oxygen fractions. However, whenever higher than normal oxygen fractions are used, SpO2 can mask existing oxygenation defects in ventilated patients. This limitation, resulting from the S shape of the oxyhemoglobin saturation curve, can be overcome by reducing the oxygen fraction delivered to the patient in a controlled and stepwise manner. This results in a SpO2/FIO2 diagram, which allows a rough characterization of a patient’s gas exchange, shunt, and the amount of lung area with a low ventilation/perfusion ratio without the need of blood sampling. On the other hand, the photoplethysmography-derived oximeter function has barely been exploited for the purpose of monitoring hemodynamics in mechanically ventilated patients. The analysis of the photoplethysmography contour provides useful real-time and noninvasive information about the interaction of heart and lungs during positive pressure ventilation. These hemodynamic monitoring capabilities are related to both the assessment of preload dependency—mainly by analyzing the breath-by-breath variation of the photoplethysmographic signals—and the analysis of arterial impedance, which examines the changes in the plethysmographic amplitude, contour, and derived indexes. In this article, we present and describe these extended monitoring capabilities and propose a more holistic monitoring concept that takes advantage of these advanced uses of pulse oximetry in the monitoring of ventilated patients. Today’s monitors need to be improved if such novel functionalities were to be offered for clinical use. Future developments and clinical evaluations are needed to establish the true potential of these advanced monitoring uses of pulse oximetry. © 2016 International Anesthesia Research Society Source

Tusman G.,Hospital Privado de Comunidad | Bohm S.H.,Swiss Center for Electronics and Microtechnology
Best Practice and Research: Clinical Anaesthesiology

General anaesthesia induces ventilation/perfusion mismatch by lung collapse. Such lung collapse predisposes patients to preoperative complications since it can persist for several hours or days after surgery. Atelectasis can be partially prevented by using continuous positive airway pressure (CPAP) and/or by lowering FiO2 during anaesthesia induction. However, these manoeuvres are dangerous for patients presenting with challenging airway or ventilator conditions. Lung recruitment manoeuvres (RMs) are ventilatory strategies that aim to restore the aeration of normal lungs. They consist of a brief and controlled increment in airway pressure to open up collapsed areas of the lungs and sufficient positive end-expiratory pressure (PEEP) to keep them open afterward. The application of RMs during anaesthesia normalises lung function along the intra-operative period. There is physiological evidence that patients of all ages and any kind of surgery benefit from such an active intervention. The effect of RMs on patient outcome in the postoperative period is, however, not yet known. © 2010 Elsevier Ltd. All rights reserved. Source

Since 1931, and especially since the Nuremberg Code of 1947, an increasing number of declarations, regulations, norms, guidelines, laws, resolutions, and rules intended to create conditions for better protection of subjects participating in research studies have been published, although some have meant setbacks in the human rights of vulnerable populations. As such, violations of the dignity of experimental subjects in clinical trials continue. What researchers investigate and how the research is done, the quality and transparency of the data, and the analysis and the publication of results (of both raw and processed data) respond to the financial interests of the pharmaceutical companies, coming into permanent tension with bioethical principles and the needs of society. The active participation of civil society is necessary to make it so that pharmaceutical research, results and applications subordinate economic benefits to the protection of human rights. Source

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