(Technically) Difficult colonoscope insertion – Tips and tricks

Cecal intubation is a critical aspect of effective, complete colonoscopy. Difficult colonoscopy is most often considered as one in which it is challenging or impossible to reach the cecum. It may be a common occurrence due to patient and/or endoscopist factors. Incomplete colonoscopies should be avoided, since patients in this context present an important prevalence of lesions that escape examination. The approach to successful cecal intubation should depend on characterization of the problem as redundant colon or difficult sigmoid colon. Most patients with a prior incomplete colonoscopy can be colonoscoped successfully, if careful attention is paid to technique, using a variety of scopes, colonoscopy methods and additional equipment. Sufficient time should be allotted to make the attempt.     

Tracheal intubation

Tracheal intubation is the act of placing a tube into the trachea. The tube enables oxygen delivery and removal of carbon dioxide, while also allowing for the administration of pharmacological agents. Intubation is the most reliable method of maintaining an airway under anaesthesia, and for protection against aspiration of stomach contents. Traditionally, intubation is achieved by direct visualization of the glottis, but now indirect laryngoscopy (via a videolaryngoscope) is a common alternative. Prior to embarking upon intubation, a thorough patient history and examination must be undertaken by the laryngoscopist; equipment must be prepared and checked; a trained assistant present; and an experienced anaesthetist available in case assistance is required. Once the endotracheal tube has been placed, correct positioning must be confirmed via both clinical examination and monitoring, including capnography. Tracheal intubation is a procedure that should only be undertaken by trained operators and is not without risk. It is important to note that it is failure to oxygenate patients rather than failure to intubate that ultimately leads to serious morbidity and mortality. The Difficult Airway Society has produced guidelines on how to manage unanticipated difficulty in tracheal intubation; it is essential that every practitioner trained to intubate patients is familiar with these algorithms and the key principles of safe airway management.     

气管插管型喉罩通气道与直接喉镜经口气管插管对血流动力学影响的比较

目的 气管插管型喉罩通气道（ILMA）为气管插管提供了一种新型途径，而且有望减轻气管插管时的心血管应激反应。但是，现有的研究结果并不一致。本研究目的在于：（1）进一步观察气管插管型喉罩通气道（ILMA）经口气管插管对血流动力学的影响；（2）证实经口气管插管时，气管插管型喉罩通气道（ILMA）是否能够比直接喉镜（DLS）产生较轻微的血流动力学反应。方法 择期整形外科手术患者53例，随机分为ILMA组和DLS组，经常规静脉诱导后气管插管。监测麻醉诱导前（基础值）、后，气管插管时和气管插管后5min内的血压（BP、收缩压SBP、舒张压DBP）和心率（HR）的变化。结果 ILMA组的平均气管插管操作时间较DLS组明显延长。气管插管后两组患者血压和心率均比麻醉诱导后明显升高，但血压的最大值未超过麻醉诱导前水平，而心率的最大值较麻醉诱导前明显升高。两组在各对应时问点的血压和心率无明显差异，血压和心率的最大值亦无明显差异。结论 在临床常用的全身麻醉深度下，ILMA和DLS经口气管插管操作引起的血流动力学反应相似。与DES相比较，ILMA引导经口气管插管并不具有减轻心血管反应的优点。     

Etomidate for Rapid-sequence Intubation in Young Children: Hemodynamic Effects and Adverse Events

OBJECTIVES: Physicians commonly use etomidate for adult rapid-sequence intubation (RSI), but the manufacturer does not recommend its use for children under 10 years of age due to a lack of data. The authors present their experience with etomidate for pediatric RSI in order to further develop its risk-benefit profile in this age group. METHODS: Trained abstractors reviewed the medical records for all children under 10 years old who received etomidate for RSI between July 1996 and April 2001. RESULTS: 105 children, with an average age of 3 (+/-2.9) years, received a median dose of 0.32 (+/-0.12) mg/kg of etomidate. The systolic blood pressure increased an average of 4 mm Hg (95% CI = -3.3 to 9.2); the diastolic blood pressure increased 7 mm Hg (95% CI = -3.1 to 11) within 10 minutes of receiving etomidate. The heart rate increased an average of 10 beats/min (95% CI = 4.0 to 17.4). Complications included three patients who vomited within 10 minutes of etomidate administration. There were no cases of documented myoclonus, status epilepticus, or new-onset seizures. Thirty-eight patients received corticosteroids during the hospital course, none for suspected adrenal insufficiency. Three patients died, all from severe brain injury. CONCLUSIONS: In children less than 10 years old, etomidate seems to produce minimal hemodynamic changes, and appears to have a low risk of clinically important adrenal insufficiency, myoclonus, and status epilepticus. The association between etomidate and emesis (observed in less than 3% of enrolled patients) remains unclear. For clinical situations in which minimal blood pressure changes during RSI are critical, etomidate appears to have a favorable risk-benefit profile for children under 10 years old.     

Noninvasive Intracranial Cerebral Flow Velocity Evaluation in the Emergency Department by Emergency Physicians

Transcranial Doppler (TCD) is an accepted modality for the evaluation of cerebral blood flow velocities. OBJECTIVES: The purpose of this study was to test the feasibility of bedside TCD measurement in the emergency department (ED) with critically ill, intubated patients. METHODS: A prospective convenience sample of patients presenting to a university hospital over a two-month period underwent TCD evaluation of the middle cerebral artery. Intubated patients with head trauma and any patient requiring tracheal intubation were eligible. A 2-MHz Doppler probe was positioned over the temporal bone to acquire blood flow velocities. An emergency medicine resident and research assistant obtained measurements. Continuous TCD tracings were recorded on a video cassette recorder tape for quality assurance review and data collection. Vital signs and therapeutic interventions were also recorded. Flow velocities were measured in cm/s; the peak Resistance Index (RI) was calculated for each patient. RESULTS: A total of 30 patients were enrolled in the study. Adequate tracings were obtained in 25 patients (83%) without a disruption of resuscitation. Tracings could not be obtained in five patients; they were listed as TCD failures. However, in two of these patients, adequate flow velocity tracings were obtained after resuscitation. Four patients were evaluated during tracheal intubation. One patient was monitored successfully during cardiopulmonary resuscitation. The median time required for data acquisition was 1.9 minutes. The mean highest RI for those who expired was 0.84. For those who survived, the mean highest RI was 0.52. The difference of 0.32 was statistically significant (p = 0.04). CONCLUSIONS: Noninvasive blood flow velocity monitoring of the middle cerebral artery using TCD is feasible in the ED when performed at the bedside on intubated patients with traumatic brain injury and others during tracheal intubation and resuscitation.     

Effects of tracheal extubation on coronary blood flow,myocardial metabolism and systemic haemodynamic responses

Global coronary blood flow and metabolism were measured in seven patients on the first postoperative day following coronary revascularization to test the hypothesis that tracheal extubation produces adverse haemodynamic responses akin to those observed during tracheal intubation. Regional coronary flow and metabolic measurements were made in five of the seven patients. Extubation from a continuous positive airway pressure (CPAP) of 5 cm H₂O was associated with a statistically significant rise in cardiac index from 3.44 ± 0.23 L · min^-1 · m^-2 to 3.73 ± 0.15L·min^-1 ·m^-2 related to an increase in stroke index, without significant changes in heart rate, mean arterial and pulmonary capillary wedge pressure. Consequently the changes in myocardial oxygen consumption (8.52 ± 0.55 to 8.85 ± 0.93 ml · min^-1) and coronary blood flow (172 ± 18 to 179 ± 17 ml·min^-1) were less prominent than those reported during intubation, where substantial rises in myocardial oxygen consumption and coronary flow occurred. Two patients experienced cardiac lactate production but there were no changes in systemic or coronary haemodynamics, nor were there clinical or electrocardiographic signs of ischaemia. We conclude that extubation does not appear to be associated with adverse systemic or coronary haemodynamic responses in patients following coronary bypass grafting. However, the revascularized myocardium may remain vulnerable to anaerobic metabolism in the immediate postoperative period. Pour savoir si comme ľintubation, ľextubation de la trachée provoque des perturbations hémodynamiques, on a mesuré le métabolisme et la circulation coronarienne globale chez sept patients, au lendemain ďun pontage aorto-coronarien. On a aussi calculé les valeurs régionales de ces mêmes variables pour cinq ďentre eux. Ľindex cardiaque de 3.44 ± 0.23 L · min^-1 · m^-2 sous pression positive en respiration spontanée (CPAP) de 5 cm. H₂O s’est élevé à 3.73 ± 0.15 L · min^-1 · m^-2 post-extubation avec une augmentation significative du volume ďéjection. La fréquence cardiaque et les pressions artérielles moyennes et capillaires pulmonaires n’ont pas changé. Ainsi ľaugmentation de la consommation ďoxygène du myocarde de 8.52 ± 0.55 à 8.85 ± 0.93 ml · min^-1 et celle du flot coronarien de 172 ± 18 à 179 ± 17 ml · min^-1 ont été moindres que celles, importantes, déjà observées lors de ľintubation. On a noté chez deux patients une production de lactate par le myocarde, sans changement de ľhémodynamic systémique et coronarienne non plus que de signe clinique ou électrocardiographique ďischémie. Donc, après un pontage coronarien, ľextubation ne semble pas causer ďeffet néfaste sur les circulations systémique et coronarienne, toutefois, le myocarde revascularisé peut demeurer sensible au métabolisme anaérobique.     

Absorption of Propranolol in Humans Following Oral,Jejunal, and Heal Administration

Pharmaceutical Research -     

Use of a double balloon enteroscope facilitates caecal intubation after incomplete colonoscopy with a standard colonoscope

BACKGROUND: Caecal intubation is a necessary step in the complete endoscopic evaluation of the colon. Studies have estimated that experienced colonoscopists may fail to reach the caecum in up to 10% of cases. AIMS: To evaluate the utility of the double balloon enteroscope used for complete examination of the colon in patients with incomplete standard colonoscopy. PATIENTS: Twenty consecutive patients with incomplete colonoscopies within the Veterans Affairs Palo Alto Health Care System. Mean age of 66 years (S.D.+/-12 years, range 46-84), 16 men. METHODS: Prospective single-centre case series on the caecal intubation rate using standard double balloon enteroscope technique in patients with previous incomplete conventional colonoscopy. RESULTS: Use of the standard double balloon enteroscope technique permitted complete colonoscopy to be achieved in 95% of the patients (19/20). Seven patients (35%) had significant pathology beyond the extent of the prior incomplete colonoscopy. We performed endoscopic mucosal resection, polypectomy or biopsy. The mean time to reach the caecum was 28 min (S.D.+/-20 min, range 6-90 min). The sedation was similar to conventional colonoscopy. No complications occurred. CONCLUSIONS: The double balloon enteroscope technology and technique can be used to complete examination of the colon in patients who were referred because of incomplete standard colonoscopy.