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The decision to intubate a patient with acute hypoxemic respiratory failure who is not in apparent respiratory distress is one of the most difficult clinical decisions faced by intensivists. A conservative approach exposes patients to the dangers of hypoxemia, while a liberal approach exposes them to the dangers of inserting an endotracheal tube and invasive mechanical ventilation. To assist intensivists in this decision, investigators have used various thresholds of peripheral or arterial oxygen saturation, partial pressure of oxygen, partial pressure of oxygen-to-fraction of inspired oxygen ratio, and arterial oxygen content. In this review we will discuss how each of these oxygenation indices provides inaccurate information about the volume of oxygen transported in the arterial blood (convective oxygen delivery) or the pressure gradient driving oxygen from the capillaries to the cells (diffusive oxygen delivery). The decision to intubate hypoxemic patients is further complicated by our nescience of the critical point below which global and cerebral oxygen supply become delivery-dependent in the individual patient. Accordingly, intubation requires a nuanced understanding of oxygenation indexes. In this review, we will also discuss our approach to intubation based on clinical observations and physiologic principles. Specifically, we consider intubation when hypoxemic patients, who are neither in apparent respiratory distress nor in shock, become cognitively impaired suggesting emergent cerebral hypoxia. When deciding to intubate, we also consider additional factors including estimates of cardiac function, peripheral perfusion, arterial oxygen content and its determinants. It is not possible, however, to pick an oxygenation breakpoint below which the benefits of mechanical ventilation decidedly outweigh its hazards. It is futile to imagine that decision making about instituting mechanical ventilation in an individual patient can be condensed into an algorithm with absolute numbers at each nodal point. In sum, an algorithm cannot replace the presence of a physician well skilled in the art of clinical evaluation who has a deep understanding of pathophysiologic principles. [ABSTRACT FROM AUTHOR]

Background: Pediatric one lung ventilation is challenging to achieve; smaller the child greater is the challenge. Challenge gets bigger due to unavailability of proper sized lung isolation devices. The aim of this case series was to assess the feasibility of using embolectomy catheter for lung isolation in 10 children who were planned to undergo lung decortication surgery. Results: Age wise predictions of airway diameters were used to select sizes of endotracheal tube and embolectomy catheter. We used a Fogarty catheter, with its tip bent to 30° and placed parallel to a cuffed endotracheal tube, under fiberoptic bronchoscope guidance to achieve lung isolation. Desired lung was deflated passively after achieving lung isolation. Embolectomy catheter cuff position was reconfirmed with bronchoscopy after patient positioning. Ages of children ranged from 2 to 6 years. Four patients required right lung isolation while six required left lung isolation. Dislodgement of embolectomy catheter while positioning or during surgery did not occur in any case. Surgeons reported good to excellent lung isolation in all the cases. All cases were successfully extubated at the end of surgery. Conclusions: Embolectomy catheter for one lung ventilation in pediatric cases maybe a useful alternative in absence of customized devices. [ABSTRACT FROM AUTHOR]

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Background: This unblinded randomised crossover study compares two endotracheal tube introducers (ETIs): the FROVA and the "Flexible Tip Bougie" (FTB), in an airway manikin mimicking difficult intubation with a percentage of glottic opening view of 30%. Participants were Emergency Medicine and Anaesthesia trainees with recent experience of less than twenty patient intubations. The primary outcome was time to intubation, further divided into time taken to pass the ETI and time to railroad the endotracheal tube (ETT) over the ETI. The secondary outcome was the difficulty of intubation. Results: The median total time to ETT placement was significantly shorter with the FTB (37.5 s) compared with the FROVA ETI (63.0 s), P = 0.0006. The median difficulty reported (scores 0–10 with 0 being no difficulty) with the FTB was 2 compared with 5 for the FROVA, P < 0.0001. Conclusions: The FTB enabled significantly faster and easier placement of the endotracheal tube compared with the FROVA in inexperienced hands intubating a difficult intubation manikin. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) microspheres were prepared using the solid-in-oil (S/O) spray-drying method to achieve the sustained release of a hydrophilic drug for the treatment of tuberculosis, via intratracheal instillation. Isoniazid (IN), a low-molecular-weight hydrophilic drug, was used as a model drug. The effects of various sizes of micronized IN powder, different drug/polymer ratios, spray-drying process parameters, and drug-release characteristics were studied to optimize the manufacturing parameters. A high entrapment efficiency (87.3%) was obtained using this method; furthermore, the microspheres were spherical and smooth. They were individually and homogenously distributed, with a mean diameter of 5.6 μm; furthermore, they showed a satisfactory extended sustained-release phase. After administration of the microspheres to rats, pulmonary drug concentrations were maintained at a relatively stable level for up to 4 weeks. [ABSTRACT FROM AUTHOR]

The tongue plays important roles in mastication, swallowing, and speech, but its sensorimotor function might be affected by endotracheal intubation. The objective of this pilot study was to describe disturbances in the sensorimotor functions of the tongue over 14 days following oral endotracheal extubation. We examined 30 post-extubated patients who had prolonged (≥48 h) oral endotracheal intubation from six medical intensive care units. Another 36 patients were recruited and examined from dental and geriatric outpatient clinics served as a comparison group. Tongue strength was measured by the Iowa Oral Performance Instrument. Sensory disturbance of the tongue was measured by evaluating light touch sensation, oral stereognosis, and two-point discrimination with standardized protocols. Measurements were taken at three time points (within 48 h, and 7 and 14 days post-extubation) for patients with oral intubation but only once for the comparison group. The results show that independent of age, gender, tobacco used, and comorbidities, tongue strength was lower and its sensory functions were more impaired in patients who had oral intubation than in the comparison group. Sensory disturbances of the tongue gradually recovered, taking 14 days to be comparable with the comparison group, while weakness of the tongue persisted. In conclusion, patients with oral endotracheal intubation had weakness and somatosensory disturbances of the tongue lasting at least 14 days from extubation but whether is caused by intubation and whether is contributed to postextubation dysphagia should be further investigated. [ABSTRACT FROM AUTHOR]

Purpose: This prospective, observational study was performed to examine the hypothesis that if conventional 7-cm head elevation is applied, laryngoscopy is more difficult for patients with anteroposterior chest diameter (chest AP diameter) outside the average range (≥17.7 or ≤14.7 cm). Methods: Chest AP diameter at the sternal notch were measured preoperatively. All patients were placed on a surgical bed with an incompressible 7-cm pillow. During laryngoscopy, the laryngeal view was graded by use of the Cormack-Lehane classification. Difficult visualization of the larynx (DVL) was defined as a grade 3 or 4 view. Results: DVL was observed for 49 patients (18.2 %). Differences between measured chest AP diameter for each patient and the calculated median value were used for statistical analysis. In univariate analysis, the difference between chest AP diameter and the median value was significantly related to DVL. Logistic regression analysis confirmed that the difference between chest AP diameter and the median value was an independent predictor of DVL (odds ratio, 3.900; 95 % confidence interval, 2.371-6.415; p < 0.001). Receiver operating characteristic curve analysis showed that this test with a test threshold of 1.5 cm had reasonable diagnostic accuracy (area under the curve of 0.748). Conclusion: When using a standard pillow size of 7 cm, chest AP diameter above or below the average range (≥17.7 or ≤14.7 cm) was a strong predictor of DVL for apparently normal-sized patients. In such cases, modification of pillow height should be considered. [ABSTRACT FROM AUTHOR]

The Airway Scope (Pentax, Tokyo, Japan) is a new device used for tracheal intubation. It allows visualization of the glottis through a non-line-of sight view. The aim of the present study was to evaluate the suitability of this device for the tracheal intubation of surgical patients. In this prospective study, the Airway Scope was used for the endotracheal intubation of 405 patients by 74 airway operators. The Airway Scope allowed visualization of the glottis in all 405 patients, including those with a Cormack-Lehane view of grade III ( n = 15) or grade IV ( n = 1) on Macintosh laryngoscopy. All tracheal intubations using the Airway Scope were successful. The mean time to complete tracheal intubation was 42.4 ± 19.7 s (±SD; range, 13–192 s). No dental damage was encountered, though minor mucosal injury caused by the blade was experienced in 2 patients. The Airway Scope consistently permitted a better intubation environment. With its potential advantages, the Airway Scope could be an effective aid to airway management in surgical patients. [ABSTRACT FROM AUTHOR]

Objective: The buildup of mucus within the endotracheal tube (ETT) progressively reduces its internal volume. We devised the Mucus Slurper as an integral part of the tracheal tube to aspirate all mucus automatically at its distal tip.Design and Setting: In vitro, and in vivo studies in sheep at the National Institutes of Health, NHLBI, PCCMB.Subjects: Six sheep, sedated, paralyzed, and mechanically ventilatedInterventions: We evaluated the Mucus Slurper in vitro, and we evaluated its efficacy and safety in three healthy sheep during 24 h on volume-controlled mechanical ventilation in comparison to three sheep managed with open tracheal tube suctioning.Measurements and Results: In vitro: with the Mucus Slurper connected to a source of vacuum of 450-500 mmHg the total volume of a single suction lasting 0.1, 0.2, and 0.3 s was, respectively, 75.4 +/- 7.9, 114.5 +/- 4.6, and 143.4 +/- 8.7 ml; with the measured vacuum within the lumen of the Mucus Slurper ring of 37 cmH2O. In vivo: during mechanical ventilation we aspirated through the Mucus Slurper 13.4 +/- 3.3 cc mucus/24 h. During the course of single aspiration the Mucus Slurper never affected the level of applied PEEP. The tracheal tube was free of tracheal secretions in the Mucus Slurper group while thin secretions were found within the ETT in the control group.Conclusion: The Mucus Slurper is a novel device designed to keep the tracheal tube and proximal trachea free of mucus. In studies in sheep lasting 24 h the Mucus Slurper was safe and prevented all mucus accumulation within the ETT. [ABSTRACT FROM AUTHOR]

There are a large number of ventilation methods for endolaryngeal laser microsurgery but unfortunately all have their drawbacks. From December 1990 to August 1992 the authors performed 57 operations using intratracheal (infraglottic) jet ventilation with specially designed equipment. The patients' tracheae were translaryngeally intubated with small bore double-lumen copper pipes and ventilation of the lungs commonly performed either with manually controlled oxygen jets or our variant of high frequency jet ventilation (HFJV), the so-called double frequency jet ventilation (DFJV). In this ventilation mode we added the conventional inflation of the lungs to basic HFJV (most often 3 Hz). This was achieved by creating the auto-PEEP, with cyclic variation of I:E ratio from 1:9 to 9:1. Surgical conditions in all cases were rated good. There were no serious complications. Important points for the avoidance of barotrauma, the most dangerous complication in these ventilation methods, are discussed extensively below. [ABSTRACT FROM AUTHOR]

Purpose. To evaluate the intratracheal route of administration as an alternative to oral administration for 2′,3′-dideoxyinosine (ddI). Methods. A ddI dose (40 mg/kg/300 µl or 6.5 mg/kg/50 µl) was instilled into the trachea in female Fisher rats and an intravenous tracer dose (9 µg/kg) of H-ddI was administered concomitantly to determine the drug clearance. Plasma concentrations were analyzed for the rate and extent of absorption. Results. ddI was rapidly absorbed from the lungs, with a bioavailability of 63% at 40 mg/kg and 101% at 6.5 mg/kg. By comparison, our previous data showed an oral bioavailability of about 15% (Pharm Res., 9:822, 1992). The distribution of a dye solution instilled intratracheally showed that a fraction of the 300 µL dose spilled over to the gastrointestinal tract, where the entire 50 µL dose was retained in the lungs. The different distribution of the two doses/volumes likely contributed to the different bioavailability, with a fraction of the higher dose/volume degraded in the gastrointestinal tract after the spillover. Absorption of ddI from the airspace of the lung was biexponential, suggesting two absorption processes. Conclusions. These data indicate significantly higher and less variable bioavailability of ddI by the intratracheal route of delivery compared to the oral route. Furthermore, the complete bioavailability at the lower dose/volume indicates no significant pulmonary first pass elimination for ddI. [ABSTRACT FROM AUTHOR]

The effects of magnesium sulfate (MgSO) as a preanesthetic medication were studied with regard to whether it can sedate or relieve a patient who is scheduled to undergo surgery, and whether it can control the hemodynamic response to tracheal intubation. Twenty adult patients in ASA status 1-2 undergoing elective surgery were studied. Ten patients received 50 mg·g MgSO intravenously by drip infusion from 30 min before the induction of anesthesia, and another ten patients received saline as a control. The changes in mean arterial pressure (MAP) and rate pressure product (RPP) after the intubation were significantly suppressed in magnesium-treated patients, but a sedative effect was not observed. Therefore, MgSO was useful as a preanesthetic medication in suppressing the hemodynamic response associated with tracheal intubation. [ABSTRACT FROM AUTHOR]

Objective: Evaluate A-mode ultrasonographic examination of maxillary sinus disease in mechanically ventilated, critically ill patients using sinoscopy as criterion standard.Design: Prospective case series.Setting: The intensive care units of a tertiary care hospital.Patients: 25 mechanically ventilated, critically ill patients with nasotracheal intubation or a tracheotomy were followed up by ultrasonographic examination of the maxillary sinuses in supine and semirecumbent positions. Infectious sinusitis was suspected in 15 patients, who were bilaterally sinoscoped combined with sampling for bacterial culture.Results: The frequency of oedema and/or secretions was high: 29 antra of 30 examined. Only 2 of 30 antra showed bacterial infection. Ultrasonographic examinations were sensitive to general pathological changes but less accurate in specific diagnostics such as the presence of secretions (sensitivity for fluid 75%, oedema 81%). The sensitivity of ultrasonographic diagnosis improved when the examination was made in the semirecumbent position (sensitivity for fluid 91%, oedema 81%).Conclusions: A-mode ultrasonography is a useful method for daily use, being easy to perform and without discomfort to the patient. It is fast and gives an immediate diagnosis. In intensive care unit patients, it should be the method of choice for day-to-day studies of effects and changes in the upper airways. For the differential diagnosis of oedema and/or secretions, it is not reliable enough to be used as the sole diagnostic method. A complementary investigation, such as computed tomography or sinoscopy, which also provides the opportunity to take samples, is needed for diagnostic confidence. [ABSTRACT FROM AUTHOR]

Pulmonary edema is a well-described complication of upper airway obstruction, most commonly caused in adults by postanesthetic laryngospasm. The mechanism initiating the formation of postobstructive pulmonary edema is believed to be the markedly negative intrapleural pressure generated by a forceful inspiratory effort against an obstructed extrathoracic airway. We herein describe a young, male patient who developed pulmonary edema postoperatively, upon emergence from anesthesia, after performing repeated, forceful inspiratory maneuvers directed against an endotracheal tube on which he had bitten down, thereby occluding it. To our knowledge, such an etiology of postobstructive pulmonary edema has not previously been described. [ABSTRACT FROM AUTHOR]