Ya-Yang Liu

Comparison of haemodynamic responses to orotracheal intubation with GlideScope ® videolaryngoscope and fibreoptic bronchoscope

Background and objective: The GlideScope® videolaryngoscope is a newly developed laryngoscope for tracheal intubation recently introduced into clinical anaesthesia. In this randomised clinical study, we compared the haemodynamic responses to orotracheal intubation using a GlideScope® videolaryngoscope and a fibreoptic bronchoscope. Methods: Fifty‐six adult patients, ASA I–II scheduled for elective plastic surgery under general anaesthesia requiring orotracheal intubation were randomly allocated to either the GlideScope® videolaryngoscope group or the fibreoptic bronchoscope group. After a standard intravenous anaesthetic induction, orotracheal intubation was performed. Noninvasive blood pressure and heart rate were recorded before and after induction, at intubation and for 5 min after intubation at 1 min intervals. Results: As compared with the post‐induction values the orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope resulted in the significant increases in blood pressures which did not exceed their baseline values. In the two groups, heart rates at intubation and within 2 min after intubation were significantly higher than their baseline values. However, there were no significant differences in blood pressures and heart rates at all time points, their maximal values and maximal percent changes during the observation and the times required to reach their maximal values between the two groups. Conclusions: The orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope produce similar haemodynamic responses.

Blood pressure and heart rate changes during intubation: a comparison of direct laryngoscopy and a fibreoptic method.

Blood pressure and heart rate changes during nasotracheal intubation under general anaesthesia were studied in 100 patients who were randomly allocated to fibreoptic bronchoscope or direct laryngoscopy intubation. Noninvasive blood pressure and heart rate were recorded before and immediately after anaesthesia induction, at anaesthesia intubation and every minute thereafter for 5 min. Nasotracheal intubation was accompanied by significant increases in blood pressure and heart rate compared to baseline values in both groups. Blood pressure and heart rate at intubation, and the maximum values of blood pressure during the observation were significantly higher in the fibreoptic bronchoscope group. However, the maximum values of heart rate were not significantly different between the two groups. Fibreoptic nasotracheal intubation may result in more severe pressor and tachycardiac responses than direct laryngoscopic nasotracheal intubation.

The circulatory responses to tracheal intubation in children: a comparison of the oral and nasal routes

The circulatory responses to laryngoscopic tracheal intubation in 62 healthy children undergoing surgery requiring tracheal intubation were studied. They were randomly assigned to receive either the oral or nasal route for intubation. Baseline non‐invasive blood pressure and heart rate were recorded following induction of anaesthesia, at intubation and then every minute for 5 min. The percentage changes of systolic blood pressure and heart rate during the measurement period were calculated. The results demonstrated that intubation time was significantly longer in the nasal group. Both oral and nasal intubation caused significant increases in blood pressure and heart rate compared to baseline and postinduction values. However, there were no significant differences found between the two groups in relation to blood pressure and heart rate. The two groups were similar with respect to the percentage changes of systolic blood pressure and heart rate during the observation period. It is concluded that oral and nasal intubation using a direct laryngoscopy can result in a similar circulatory response in anaesthetised children.

A comparative study of hemodynamic responses to orotracheal intubation with fiberoptic bronchoscope and laryngoscope in children

Background : The purposes of this study were to further identify the hemodynamic responses to orotracheal intubation in children, using a fiberoptic bronchoscope (FOB) and a direct laryngoscope (DLS), and to validate whether the FOB can attenuate the hemodynamic response to orotracheal intubation compared with the DLS.

Determining predictive value of preoperative tests for difficult intubation

In the recent article by Mahmoodpoor et al. [1] evaluating the predictive value of several preoperative tests for difficult intubation in a prospective descriptive study, they conclude that facial angle has a high sensitivity, positive and negative predictive value, and Youden index for prediction of difficult intubation, but the best result is achieved when facial angle is used in combination with either the modified Mallampati score or upper lip bit test. As difficult intubation prediction by preoperative tests is a crucial component of safe airway management algorithm [2], their findings have potential implications. However, several aspects of this study would have made interpretation of their findings questionable. First, the main aim of this study was to evaluate the predictive value of preoperative tests for difficult intubation, which was defined as the Cormack and Lehane grades 3 and 4 laryngoscopic views. According to the latest standards of difficult airways by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway [2], however, the Cormack and Lehane grades 3 and 4 laryngoscopic views should actually be defined as difficult laryngoscopy, rather than difficult intubation. It must be emphasized that the laryngeal view obtained by direct laryngoscopy is often used as a primary variable for difficult or failed intubation, but they are not synonymous in the majority of patients [3]. Tracheal intubation depends more on the skill of the intubator than does laryngoscopy, and therefore the degrees of difficulty with direct laryngoscopy and tracheal intubation may be inconsistent. For example, some patients with a Cormack and Lehane grade 3 or 4 laryngoscopic view may be intubated by an experienced anesthesiologist at the first or second attempt if the distal end of the tracheal tube is appropriately curved by a malleable stylet or a introducer (e.g., a gum elastic bougie) is used [4]. As this study did not evaluate and report the occurrence of difficult intubation, we argue that their conclusions should be modified. Second, the laryngoscopic views using the Cormack-Lehane classification was stated as the primary endpoint. Besides the patients head was placed in the “sniffing” position, the readers were not provided with the experience of intubator and the use of external laryngeal manipulation during laryngoscopy. Thus, it was unclear whether an optimal laryngoscopy attempt was carried out in each patient. To obtain the optimal laryngoscopy attempt, a reasonably experienced intubator who has had at least 3

Current evidence for the use of C-MAC videolaryngoscope in adult airway management: a review of the literature

The C-MAC videolaryngoscope is the first Macintosh-typed videolaryngoscope. Since the advent of its original version video Macintosh system in 1999, this device has been modified several times. A unique feature of C-MAC device is its ability to provide the 2 options of direct and video laryngoscopy with the same device. The available evidence shows that in patients with normal airways, C-MAC videolaryngoscope compared with direct laryngoscopy can provide comparable or better laryngeal views and exerts less force on maxillary incisors, but does not offer conclusive benefits with regard to intubation time, intubation success, number of intubation attempts, the use of adjuncts, and hemodynamic responses to intubation. In patients with predicted or known difficult airways, C-MAC videolaryngoscope can achieve a better laryngeal view, a higher intubation success rate and a shorter intubation time than direct laryngoscopy. Furthermore, the option to perform direct and video laryngoscopy with the same device makes C-MAC videolaryngoscope exceptionally useful for emergency intubation. In addition, the C-MAC videolaryngoscope is a very good tool for tracheal intubation teaching. However, tracheal intubation with C-MAC videolaryngoscope may occasionally fail and introduction of C-MAC videolaryngoscope in clinical practice must be accompanied by formal training programs in normal and difficult airway managements.

Current Evidences for the Use of UEscope in Airway Management

Objective: UEscope is a new angulated videolaryngoscope (VL). This review aimed to describe the features of UEscope and provide clinical evidences regarding the efficacy and safety of this video device in adult tracheal intubation and its roles in airway management teaching. Data Sources: The Wan Fang Data, CNKI, PubMed, Embase, Cochrane Library, and Google Scholar were searched for relevant English and Chinese articles published up to January 15, 2017, using the following keywords: “HC video laryngoscope”, “UE videolaryngoscope”, “video laryngoscope”, and “videolaryngoscopy”. Study Selection: Human case reports, case series, observable studies, and randomized controlled clinical trials were included in our search. The results of these studies and their reference lists were cross-referenced to identify a common theme. Results: UEscope features the low-profile portable design, intermediate blade curvatures, all-angle adjustable monitor, effective anti-fog mechanisms, and built-in video recording function. During the past 5 years, there have been a number of clinical studies assessing the application and roles of UEscope in airway management and education. As compared with direct laryngoscope, UEscope improves laryngeal visualization, decreases intubation time (IT), and increases intubation success rate in adult patients with normal and difficult airways. These findings are somewhat different from the previous results regarding the other angulated VLs; they can provide an improved laryngeal view, but no conclusive benefits with regard to IT and intubation success rate. Furthermore, UEscope has extensively been used for intubation teaching and shown a number of advantages. Conclusions: UEscope can be used as a primary intubation tool and may provide more benefits than other VLs in patients with normal and difficult airways. However, more studies with large sample are still needed to address some open questions about clinical performance of this new VL.

Assessing Effects of Preoperative Anemia on Adverse Outcomes After Coronary Surgery

To the Editor, The recent article by Tauriainen et al [1] showed that after adjusting important baseline characteristics, operative factors, severity of perioperative bleeding and amount of transfused blood products by propensity score matching, regression and Cox proportional hazards analyses, preoperative anemia was not associated with an increased risk of short and late mortality. Other than the limitations described in discussion, we would like to make some comments on this study. First, in a retrospective study, the propensity score matching is indeed useful for adjusting the patients’ baseline characteristic and controlling selection biases. Nevertheless, an important limitation of propensity score matching is that the analysis is necessarily restricted to the matched sets [2]. In this study, to generate two propensityscore-matched groups, more than 70% of patients without preoperative anemia were excluded, while only about 14% of patient with preoperative anemia were excluded. We are concerned that loss of most non-anemic patients may shift the estimation target as the effect of non-anemia on the postoperative outcomes may no longer represent the effect for all non-anemic patients. Thus, findings of this study may only show the relation between preoperative anemia and postoperative short and late mortality in matched patients, but may not be representative of the full sample. Second, no matter what propensity score matching or regression analysis is used for risk adjustment, the statistical models carry the significant assumption of no unmeasured confounders; namely, all important known risk factors affecting the measured outcomes must be measured and taken into account within the model [2]. Apparently, this is an unrealistic assumption for study of Tauriainen et al, as many known perioperative risk factors affecting postoperative mortality of patients undergoing cardiac surgery were not considered into the models when propensity score matching and regression analysis were used for risk adjustments, for instance, preoperative hypoproteinemia, perioperative cardiac medications, intraoperative hemodynamic instability, postoperative anemia, delirium, respiratory failure, dialysis, sepsis, gastrointestinal complications [3, 4]. That is, even if after risk adjustments, many unmeasured confounders still exist and there may remain imbalance in unmeasured confounders between groups in this study. Thus, we argue that imbalance in unmeasured confounders would have biased the true effect of preoperative anemia on the adverse outcomes after CABG surgery or even resulted in a spurious association between preoperative anemia and postoperative mortality. Third, this study assessed the effects of preoperative anemia on short and late mortality. In fact, there are important differences in mortality risk factors between the early and late periods after CABG surgery, i.e., the majority of predictors of early mortality are cardiac-related variables, whereas the majority of predictors of late mortality are noncardiac-related variables and late mortality is mainly attributable to many causes, not necessarily related to patients’ cardiovascular and general health before surgery [5]. Thus, adjusting same preoperative and intraoperative confounders for short and late mortality in this study may be arbitrary and can confuse the interpretation of results. & Fu-Shan Xue xuefushan@aliyun.com

Association between intraoperative blood product transfusions and acute kidney injury following cardiac surgery

With great interest, we read the recent article by Kindzelski et al.1 assessing the association between intraoperative blood product transfusions and acute kidney injury (AKI) following cardiac surgery. By binary logistic regression analysis, they show that intraoperative blood product transfusions are independently associated with an increased risk of postoperative AKI. Furthermore, there is a stepwise increase in the probability of postoperative 30-day mortality with escalating AKI severity. In this study, the authors had used appropriate statistical methods to evaluate the influence of intraoperative blood transfusion on the occurrence of AKI and determine the association between postoperative AKI stages and mortality. However, this study is a retrospective analysis, which potentially introduces a number of confounders. Other than the limitations described in the discussion, we note that several issues of this study were not well addressed. First, when determining the association of intraoperative blood transfusion with postoperative AKI stages by logistic regression analysis, intraoperative variables used for risk adjustments only included type of surgery (CABG, valvular, both) and cross-clamp time, but not other important intraoperative variables associated with AKI, especially for hemoglobin levels during cardiopulmonary bypass. It has been shown that hemodilution anemia during cardiopulmonary bypass is independently associated with AKI after cardiac surgery, especially when prolonged cardiopulmonary bypass time and intraoperative transfusion are needed.2 Furthermore, the simultaneous occurrence of both hemodilution anemia and hypotension during cardiopulmonary bypass can synergistically act to increase the risk of AKI after cardiac surgery.3 We are concerned that the neglect of important intraoperative factors for risk adjustments would have biased the true contribution of intraoperative blood transfusion to the occurrence of postoperative AKI. Second, this study only focused on the influence of intraoperative blood transfusion on the development of postoperative AKI. The available evidence shows that blood transfusion after cardiac surgery is also an independent risk factor of postoperative AKI.4,5 Finally, when evaluating the association of escalating AKI severity with postoperative 30-day mortality by logistic regression analysis, postoperative anemia and blood transfusion were not included in the model for risk adjustment. Similarly, postoperative blood transfusion has also been associated independently with the increased risk of adverse events and mortality after cardiac surgery.6 Furthermore, postoperative anemia is common and frequently persists for months after cardiac surgery. When the postoperative hemoglobin level is considered as a continuous variable, every 1 mg/dl decrease in hemoglobin level is associated with a 13% increase in adverse cardiovascular events and a 22% increase in all-cause mortality.7 Thus, not taking postoperative anemia and blood transfusion into account would have tampered with the inference of the logistic regression model for adjusted impacts of AKI stages on postoperative 30-day mortality.

Effects of enteral different-dose levothyroxinesodium pretreatment on serum thyroid hormone levels and myocardial ischemia-reperfusion injury

Introduction: The available evidence shows that perioperative oral thyroid hormone can significantly attenuate the postoperative decline in the serum hormone level and improve postoperative hemodynamic and prognostic parameters. However, there has been no study assessing the effects of preoperative oral different-dose thyroid hormone on serum hormone levels and myocardial ischemia-reperfusion injury (IRI) after cardiac surgery. Methods: Forty-eight healthy Wistar rats, aged 35 days, were randomly allocated into six groups: Group BC, Group C and four pretreatment groups in which the rats were given levothyroxine-sodium of 10 μg, 20 μg, 40 μg and 80 μg/100 g. On the eighth day, the serum thyroid hormone levels were determined and then an isolated heart ischemia-reperfusion model was established with a Langendorff apparatus. Results: Compared with Groups BC and C, serum thyroid hormone levels on the eighth day did not significantly change in Group 10 μg, but were significantly increased in Groups 20 μg, 40 μg and 80 μg. The cardiac enzyme myocardial-bound creatine kinase levels in the coronary effluent during reperfusion were significantly lower in Groups 10 μg and 20 μg and 40 μg than in Group C. The recovery rates of +dp/dtmax and -dp/dtmax at 30 min during reperfusion were significantly lower in Groups 40 μg and 80 μg than in Groups 10 μg and 20 μg. Compared with Group C, myocardial expressions of heat shock protein 70 and myosin heavy chain α were increased in the four experiment groups and myocardial expression of thyroid hormone receptor α1 was significantly increased in Groups 20 μg, 40 μg and 80 μg. Conclusions: The pretreatment with enterally smaller doses levothyroxine-sodium does not significantly affect serum thyroid hormone levels and produces protection against myocardial IRI, whereas pretreatment with enterally larger doses of levothyroxine-sodium can only provide an attenuated or insignificant cardioprotection because of hyperthyroxinemia. Cardioprotection by levothyroxine-sodium pretreatment is probably attributable to increased myocardial expression of heat shock protein 70 and myosin heavy chain α.