The effects on arterial haemoglobin oxygen saturation and on shunt of increasing cardiac output with dopamine or dobutamine during one-lung ventilation

Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsTheoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial saturation should improve as the venous oxygen extraction per ml of blood decreases if the total oxygen consumption remains constant. Previous work demonstrated that this was not achieved with adrenaline or isoprenaline as increased shunting negated any benefit from improved cardiac output and mixed venous oxygen content. However, pharmacological stimulation of cardiac output and venous oxygen without any increase in shunt should achieve the goal of improved arterial oxygenation. To test this hypothesis, seven pigs were subjected to one-lung ventilation and infused on separate occasions, with dopamine and with dobutamine in random order to increase the cardiac output. The mixed venous oxygen content, shunt fraction, oxygen consumption and arterial oxygen saturation were measured. With both dopamine and dobutamine there was a consistent rise in venous oxygen content. However, with dopamine, the mean shunt rose from 28% to 42% and with dobutamine, the mean shunt rose from 45% to 59% (both changes P<0.01). With dopamine, the mean arterial oxygen saturation fell by 4.7%, and with dobutamine by 2.9%, but neither fall was statistically significant. It is concluded that any benefit to arterial saturation which might occur from a dopamine- or dobutamine-induced increase in mixed venous oxygen content during one-lung ventilation is offset by increased shunting. During one-lung anaesthesia, there would appear to be no benefit to arterial saturation in increasing cardiac output with an infusion of either dopamine or dobutamine.W. J. Russell, M. F. Jameshttp://www.aaic.net.au/Article.asp?D=200331

Effect of intraoperative constant rate infusion of lidocaine on short-term survival of dogs with septic peritonitis: 75 cases (2007-2011)

OBJECTIVE To investigate whether intraoperative administration of a lidocaine infusion to dogs with septic peritonitis was associated with short-term (48 hours) survival after surgery. DESIGN Retrospective case series. ANIMALS 75 dogs with septic peritonitis. PROCEDURES Medical records of dogs with septic peritonitis that underwent laparotomy between January 2007 and December 2011 at the Royal Veterinary College were reviewed. Select variables during the preoperative, intraoperative, and postoperative periods and short-term survival after surgery were compared between dogs that received an opioid only (group O; n = 33) and dogs that received lidocaine (50 \u3bcg/kg/min [22.7 \u3bcg/kg/min], IV; group L; 42) in addition to an opioid during surgery. RESULTS The proportion of dogs that survived for 48 hours after surgery was significantly greater for group L (35/42) than for group O (20/33). Intraoperative infusion of lidocaine increased the odds of short-term survival (OR, 8.77; 95% CI, 1.94 to 39.57). No significant differences were observed between the 2 treatment groups for variables assessed during the preoperative and postoperative periods. During the intraoperative period, more dogs in group L received an IV bolus of a synthetic colloid than did dogs in group O, but the number of IV boluses administered was not associated with short-term survival. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that IV infusion of lidocaine might improve the short-term survival of dogs with septic peritonitis. Prospective clinical trials are necessary to determine the efficacy of lidocaine as a supportive treatment for dogs with septic peritonitis

A Role for the SmpB-SsrA System in Yersinia pseudotuberculosis Pathogenesis

Yersinia utilizes a sophisticated type III secretion system to enhance its chances of survival and to overcome the host immune system. SmpB (small protein B) and SsrA (small stable RNA A) are components of a unique bacterial translational control system that help maintain the bacterial translational machinery in a fully operational state. We have found that loss of the SmpB-SsrA function causes acute defects in the ability of Yersinia pseudotuberculosis to survive in hostile environments. Most significantly, we show that mutations in smpB-ssrA genes render the bacterium avirulent and unable to cause mortality in mice. Consistent with these observations, we show that the mutant strain is unable to proliferate in macrophages and exhibits delayed Yop-mediated host cell cytotoxicity. Correspondingly, we demonstrate that the smpB-ssrA mutant suffers severe deficiencies in expression and secretion of Yersinia virulence effector proteins, and that this defect is at the level of transcription. Of further interest is the finding that the SmpB-SsrA system might play a similar role in the related type III secretion system that governs flagella assembly and bacterial motility. These findings highlight the significance of the SmpB-SsrA system in bacterial pathogenesis, survival under adverse environmental conditions, and motility

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

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&apos; 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

Ribosomal protein S1 influences trans-translation in vitro and in vivo

When the bacterial ribosome stalls on a truncated mRNA, transfer–messenger RNA (tmRNA) acts initially as a transfer RNA (tRNA) and then as a messenger RNA (mRNA) to rescue the ribosome and add a peptide tag to the nascent polypeptide that targets it for degradation. Ribosomal protein S1 binds tmRNA but its functional role in this process has remained elusive. In this report, we demonstrate that, in vitro, S1 is dispensable for the tRNA-like role of tmRNA but is essential for its mRNA function. Increasing or decreasing the amount of protein S1 in vivo reduces the overall amount of trans-translated proteins. Also, a truncated S1 protein impaired for ribosome binding can still trigger protein tagging, suggesting that S1 interacts with tmRNA outside the ribosome to keep it in an active state. Overall, these results demonstrate that S1 has a role in tmRNA-mediated tagging that is distinct from its role during canonical translation

Tumor cell heterogeneity and resistance; report from the 2018 Coffey‐Holden Prostate Cancer Academy Meeting

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147081/1/pros23729.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147081/2/pros23729_am.pd