Hypoxemia during one-lung ventilation: prediction, prevention,

When switching from two-lung to one-lung ventilation (OLV), shunt fraction increases, oxygenation is impaired, and hypoxemia may occur. Hypoxemia during OLV may be predicted from measurements of lung function, distribution of perfusion between the lungs, whether the right or the left lung is ventilated, and whether the operation will be performed in the supine or in the lateral decubitus position. Hypoxemia during OLV may be prevented by applying a ventilation strategy that avoids alveolar collapse while minimally impairing perfusion of the dependent lung. Choice of anesthesia does not influence oxygenation during clinical OLV. Hypoxemia during OLV may be treated symptomatically by increasing inspired fraction of oxygen, by ventilating, or by using continuous positive airway pressure in the nonventilated lung. Hypoxemia during OLV may be treated causally by correcting the position of the double-lumen tube, clearing the main bronchi of the ventilated lung from secretions, and improving the ventilation strategy. ONE-LUNG ventilation (OLV) is required for a number of thoracic procedures, such as lung, esophageal, aortic, or mediastinal surgery. Although OLV is not mandatory for all such procedures, it almost always improves access to the operation field and expedites the process of operation. For this reason and because anesthesiologists' expertise in placement and monitoring of double-lumen tubes (DLTs) has increased, OLV is now used for almost all thoracic operations in which the lung is operated on or in which the collapse of the lung improves access to the operation field. During OLV, although only one lung is ventilated, both lungs are perfused. Perfusion of the collapsed, nonventilated lung leads inevitably to transpulmonary shunting, to impairment of oxygenation, and, occasionally, to hypoxemia. In a recent study, 1 we found that hypoxemia during OLV, defined by a decrease in arterial hemoglobin oxygen saturation (SaO 2 ) to less than 90%, occurred in 4% of patients whose lungs were ventilated with a fraction of inspired oxygen (FIO 2 ) greater than 0.5. Other studies 2-5 using similar definitions of hypoxemia place the rate at 5-10%. Hypoxemia during OLV may affect the safety of the patient and is a challenge for the anesthesiologist and for the surgeon. It is therefore important to predict, to prevent if possible, and to promptly treat hypoxemia during OLV. Prediction of Hypoxemia during OLV A number of factors may be helpful in predicting oxygenation during OLV. However, it must be kept in mind that none of these factors alone can accurately predict whether an individual patient will become hypoxemic during OLV. Side of Operation Because the right lung is larger than the left lung, it is not surprising that oxygenation during OLV is better during left thoracotomy (i.e., when the larger right lung is the dependent, ventilated lung). Lung Function Abnormalities Although lung function abnormalities may predispose to hypoxemia during OLV, not all measures of lung function are reliable indicators. Indeed, some studies show a clearly paradoxical effect: Some indicators of airway obstruction in lung function tests show a negative correlation with oxygenation during OLV, meaning that the more severe the obstruction is, the less likely it is that the patient will experience hypoxemia during OLV. In retrospective and prospective studies, Slinger et al. 2 found that the less the forced expiratory volume was in 1 s, the better the oxygenation was during OLV. One explanation provided for this paradoxical relation may be that air trapping in the ventilated lung may generate auto-positive end-expiratory pressure (PEEP) during OLV, thus decreasing the likelihood of atelectasis in the ventilated lung and improving oxygenation. Also, air trapping in the nonventilated lung may delay the onset of desaturation. However, other studies have not found any relation between degree of auto-PEEP and oxygenation during OLV, 7 and another recent study did not find Received from Klinik für Anästhesie und Intensivmedizin, Zentralklinik Bad Berka GmbH, Bad Berka, Germany, and Klinik für Anästhesiologie, Klinikum Saarbrücken, Saarbrücken, Germany. Submitted for publication August 26, 2008. Accepted for publication January 2, 2009. Support was provided solely from institutional and/or departmental sources. Literature search: The terms one-lung ventilation, single-lung ventilation, anesthesia and thoracic surgery, hypoxemia and thoracic surgery were used in MEDLINE (PubMed) to obtain a primary list of references. Titles, abstracts, and reference list of the primary list were then screened to obtain studies relevant to the topics in this review

A Special, Modified, Double-Lumen Tube for One-Lung Ventilation in Pigs

Animal studies in pigs often depend in thoracic anaesthesia on effective lung separation. In this report we describe the use of a modified double-lumen endotracheal tube for one-lung or differential lung ventilation in pigs resulting in excellent lung separation and unimpaired hypoxic pulmonary vasoconstriction

Thoracic Anesthesia during the COVID-19 Pandemic: 2021 Updated Recommendations by the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) Thoracic Subspecialty Committee

The novel coronavirus pandemic has radically changed the landscape of normal surgical practice. Lifesaving cancer surgery, however, remains a clinical priority, and there is an increasing need to fully define the optimal oncologic management of patients with varying stages of lung cancer, allowing prioritization of which thoracic procedures should be performed in the current era. Healthcare providers and managers should not ignore the risk of a bimodal peak of mortality in patients with lung cancer; an imminent spike due to mortality from acute coronavirus disease 2019 (COVID-19) infection, and a secondary peak reflecting an excess of cancer-related mortality among patients whose treatments were deemed less urgent, delayed, or cancelled

Application of multivariate curve resolution alternating least squares (MCR-ALS) to the quantitative analysis of pharmaceutical and agricultural samples

10 pages, 6 figures, 3 tables.-- PMID: 18371770 [PubMed].-- Available online Aug 30, 2007.Application of multivariate curve resolution alternating least squares (MCR-ALS), for the resolution and quantification of different analytes in different type of pharmaceutical and agricultural samples is shown. In particular, MCR-ALS is applied first to the UV spectrophotometric quantitative analysis of mixtures of commercial steroid drugs, and second to the near-infrared (NIR) spectrophotometric quantitative analysis of humidity and protein contents in forage cereal samples. Quantitative results obtained by MCR-ALS are compared to those obtained using the well established partial least squares regression (PLSR) multivariate calibration method.Peer reviewe