Asphyxiation by an inhaled foreign body is a leading cause of accidental death among children younger than 4 years. A review article examining 12,979 paediatric bronchoscopies made the following observations: Epidemiology
Most aspirated foreign bodies are organic materials (81%, confidence interval [CI] = 77%-86%), nuts and seeds being the most common.
The majority of foreign bodies (88%, CI = 85%-91%) lodge in the bronchial tree, with the remainder catching in the larynx or trachea.
The incidence of right-sided foreign bodies (52%, CI = 48%-55%) is higher than that of left-sided foreign bodies (33%, CI = 30%-37%). A small number of objects fragment and lodge in different parts of the airways.
A history of a witnessed choking event is highly suggestive of an acute aspiration.
A history of cough is highly sensitive for foreign body aspiration but is not very specific. On the other hand, a history of cyanosis or stridor is very specific for foreign body aspiration but is not very sensitive.
Signs and symptoms typical in delayed presentations include unilateral decreased breath sounds and rhonchi, persistent cough or wheezing, recurrent or nonresolving pneumonia, or rarely, pneumothorax.
Only 11% (CI = 8%-16%) of the foreign bodies were radio-opaque on radiograph, with chest radiographs being normal in 17% of children (CI = 13%-22%).
The common radiographic abnormalities included localized emphysema and air trapping, atelectasis, infiltrate, and mediastinal shift.
Although rigid bronchoscopy is the traditional diagnostic “gold standard,” the use of computerized tomography, virtual bronchoscopy, and flexible bronchoscopy is increasing.
Reported mortality during bronchoscopy is 0.42%.
Although asphyxia at presentation or initial emergency bronchoscopy causes some deaths, hypoxic cardiac arrest during retrieval of the object, bronchial rupture, and unspecified intraoperative complications in previously stable patients constitute the majority of in-hospital fatalities.
Major complications include severe laryngeal edema or bronchospasm requiring tracheotomy or reintubation, pneumothorax, pneumomediastinum, cardiac arrest, tracheal or bronchial laceration, and hypoxic brain damage (0.96%).
Aspiration of gastric contents is not reported.
End expiratory film: delayed emptying of the left lung suggests local air trapping Anaesthetic considerations
Preoperative assessment should determine where the aspirated foreign body has lodged, what was aspirated, and when the aspiration occurred (“what, where, when”).
The choices of inhaled or IV induction, spontaneous or controlled ventilation, and inhaled or IV maintenance may be individualized to the circumstances. Although several anesthetic techniques are effective for managing children with foreign body aspiration, there is no consensus from the literature as to which technique is optimal.
An induction that maintains spontaneous ventilation is commonly practiced to minimize the risk of converting a partial proximal obstruction to a complete obstruction.
Controlled ventilation combined with IV drugs and paralysis allows for suitable rigid bronchoscopy conditions and a consistent level of anesthesia.
Close communication between the anesthesiologist, bronchoscopist, and assistants is essential.
Chest x-rays often miss pneumothoraces in the trauma room. These are occult pneumothoraces. A study using agreement by two fellowship trained radiologists as the gold standard for CXR interpretation showed that 80% of these were truly occult, ie. not detectable by the radiologists from CXR and only demonstrable on CT. Of those seven cases that could or should have been identified by emergency physicians (ie. ‘missed’ pneumothoraces) subcutaneous emphysema (5), pleural line (3), and deep sulcus sign (2) were detected by the radiologist reviewers.
This serves both as a reminder of the signs to look for on CXR for pneumothorax, and of the inadequacy of plain radiography in trauma patients. The authors advise in their discussion that ‘Thoracic ultrasonography may be the ideal diagnostic modality as it has a high sensitivity for the detection of PTX and it may be performed quickly at the bedside while maintaining spinal precautions’.
If you don’t know how to detect a pneumothorax with ultrasound yet, have a look here. Occult Pneumothoraces Truly Occult or Simply Missed: Redux J Trauma. 2010 Dec;69(6):1335-7
Evidence-based medicine reminds us to beware ‘experts’. However, here’s one self-described expert who talks some sense. Doctor (Doktor?) HJ Priebe from the University Hospital Freiburg in Germany suggests the risk of harm outweighs the risk of benefit from this procedure:
‘Despite the lack of evidence for its effectiveness and evidence for numerous deleterious effects, cricoid pressure is still considered a standard of care during rapid sequence induction, and its application is considered mandatory in patients at high risk for gastric regurgitation. However, by using cricoid pressure, we may well be endangering more lives by causing airway problems than we are saving in the hope of preventing pulmonary aspiration. It is dangerous to consider cricoid pressure to be an effective and reliable measure in reducing the risk of pulmonary aspiration and to become complacent about the many factors that contribute to regurgitation and aspiration. Cricoid pressure is not a substitute for optimal patient preparation. Ensuring optimal positioning and a rapid onset of anesthesia and muscle relaxation to decrease the risk of coughing, straining or retching during the induction of anesthesia are likely more important in the prevention of pulmonary aspiration than cricoid pressure.
‘At the time of Sellick’s description of the technique of cricoid pressure, morbidity and mortality from pulmonary aspiration during the induction of anesthesia in the surgical population in general, and the obstetric population in particular, were of great concern. At that time, the concept of cricoid pressure was highly attractive. However, during the past 48 years, many aspects of anesthetic management have considerably changed, and knowledge has advanced. By today’s standards, cricoid pressure can no longer be considered an evidence-based practice. This is why more and more anesthetists (including myself) no longer apply cricoid pressure.‘
Vielen Dank, Herr Doktor! Cricoid pressure: an expert’s opinion Minerva Anestesiol 2009;75:710-4 – Full text
Just as well really, because these guys show many people don’t know how to do it anyway! Cases were identified in which pressure was mistakenly applied to the thyroid cartilage and even the sternocleidomastoid muscles! Variable application and misapplication of cricoid pressure J Trauma. 2010 Nov;69(5):1182-4
The complication rate after a negative or nontherapeutic laparotomy is reported to be substantial but most of this reported morbidity is because of associated injuries and is not related to the abdominal exploration. On the other hand, the morbidity and mortality associated with a delay in taking the injured patient to the operating room is well recognised. A retrospective study attempts to show that when injury severity (using TRISS) is controlled for, negative laparotomy did not significantly increase the complication burden compared with no laparotomy in blunt abdominal trauma patients. “Never Be Wrong”: The Morbidity of Negative and Delayed Laparotomies After Blunt Trauma J Trauma. 2010 Dec;69(6):1386-92
BACKGROUND: : We aimed to investigate the value of the diameter of the inferior vena cava (IVC) on initial computed tomography (CT) to predict hemodynamic deterioration in patients with blunt torso trauma.
METHODS: : We reviewed the initial CT scans, taken after admission to emergency room (ER), of 114 patients with blunt torso trauma who were consecutively admitted during a 24-month period. We measured the maximal anteroposterior and transverse diameters of the IVC at the level of the renal vein. Flat vena cava (FVC) was defined as a maximal transverse to anteroposterior ratio of less than 4:1. According to the hemodynamic status, the patients were categorized into three groups. Patients with hemodynamic deterioration after the CT scans were defined as group D (n = 37). The other patients who remained hemodynamically stable after the CT scans were divided into two groups: patients who were hemodynamically stable on ER arrival were defined as group S (n = 60) and those who were in shock on ER arrival and responded to the fluid resuscitation were defined as group R (n = 17).
RESULTS: : The anteroposterior diameter of the IVC in group D was significantly smaller than those in groups R and S (7.6 mm ± 4.4 mm, 15.8 mm ± 5.5 mm, and 15.3 mm ± 4.2 mm, respectively; p < 0.05). Of the 93 patients without FVC, 16 (17%) were in group D, 14 (15%) required blood transfusion, and 8 (9%) required intervention. However, of the 21 patients with FVC, all patients were in group D, 20 (95%) required blood transfusion, and 17 (80%) required intervention. The patients with FVC had higher mortality (52%) than the other patients (2%).
CONCLUSION: : In cases of blunt torso trauma, patients with FVC on initial CT may exhibit hemodynamic deterioration, necessitating early blood transfusion and therapeutic intervention.
Predictive Value of a Flat Inferior Vena Cava on Initial Computed Tomography for Hemodynamic Deterioration in Patients With Blunt Torso Trauma J Trauma. 2010 Dec;69(6):1398-402
Measuring end-tidal carbon dioxide (ET CO2 ) is a practical non-invasive method for detecting pulmonary blood flow, reflecting cardiac output and thereby the quality of CPR. It has also been shown to rise before clinically detectable return of spontaneous circulation (ROSC).
Passive leg raising (PLR) increases venous return and may therefore augment cardiac output and in a cardiac arrest this may be reflected by an elevation in ETCO2.
A Swedish observational study of 126 patients with out of hospital cardiac arrest due to a likely cardiac aetiology underwent tracheal intubation with standardised ventilation and chest compressions (either manually or using the LUCAS device, as part of larger study of mechanical chest compressions according to a cluster design). Patients were stratified to receive either PLR to 20 degrees or no PLR. ETCO2 was measured during CPR, either for 15min, or until the detection of ROSC. Hang on I think that's overdoing it a bit
During PLR, an increase in ETCO2 was found in all 44 patients who received PLR within 15s (p=0.003), 45s (p = 0.002) and 75 s (p = 0.0001). Survival to hospital discharge was 7% among patients with PLR and 1% among those without PLR (p = 0.12). Among patients experiencing ROSC (60 of 126), there was a marked increase in ETCO2 1 min before the detection of a palpable pulse. Passive leg raising during cardiopulmonary resuscitation in out-of-hospital cardiac arrest—Does it improve circulation and outcome? Resuscitation. 2010 Dec;81(12):1615-20
Therapeutic hypothermia (TH) has been associated with improved outcomes in term infants who present with moderate hypoxic-ischaemic encephalopathy (HIE). However, in the three major studies the time to initiate cooling was at approximately 4.5 postnatal hours. Many newborns are referred to specialist centres where cooling takes place from outlying hospitals (‘outborn’). It may be the case that earlier initiation of TH could improve outcomes, leading Takenouchi and colleagues to propose a ‘Chain of Brain Preservation’.
‘Given that most infants are outborn, a time sensitive education metaphor termed Chain of Brain Preservation may facilitate early recognition of high risk infants and thus earlier treatment.‘ Chain of Brain Preservation—A concept to facilitate early identification and initiation of hypothermia to infants at high risk for brain injury Resuscitation. 2010 Dec;81(12):1637-41
Two dedicated devices for transtracheal oxygen delivery through a cricothyroidotomy needle are available, the ENK Oxygen Flow Modulator (ENK) and the Manujet. Both maintain oxygenation, but the ENK is thought to achieve better ventilation (as previously shown in a pig model) because of a continuous flow that provides CO2 washout between insufflations. Very little is known concerning the lung pressures generated with these 2 devices, so a study using a simulated trachea and artificial lung model sought to determine oxygen flow, tidal volumes, and airway pressures at different occlusion rates and during both simulated partial and complete upper airway obstruction. Manujet
Gas flow and tidal volume were 3 times greater with the Manujet than the ENK (approximately 37 vs 14 L/min and 700 vs 250 mL, respectively) and were not dependent on the respiratory rate. In the absence of ventilation, the ENK delivered a 0.6+/-0.1 L/min constant gas flow. In the totally occluded airway, lung pressures increased to 136 cm H2O after 3 insufflations with the Manujet, whereas the ENK, which has a pressure release vent, generated acceptable pressures at a low respiratory rate (4 breaths/min) (peak pressure at 27.7 +/-0.7 and end-expiratory pressure at 18.8+/- 3.8 cm H2O). When used at a respiratory rate of 12 breaths/min, the ENK generated higher pressures (peak pressure at 95.9 +/- 21.2 and end-expiratory pressure at 51.4+/- 21.4 cm H2O). In the partially occluded airway, lung pressures were significantly greater with the Manujet compared with the ENK, and pressures increased with the respiratory rate with both devices. Finally, the gas flow and tidal volume generated by the Manujet varied proportionally with the driving pressure.
The authors asset that this study confirms:
the absolute necessity of allowing gas exhalation between 2 insufflations and
maintaining low respiratory rates during transtracheal oxygenation.
In the case of total airway obstruction, the ENK may be less deleterious because it has a pressure release vent. Using a Manujet at lower driving pressures may decrease the risk of barotrauma and allow the safe use of higher respiratory rates ENK Oxygen delivery during transtracheal oxygenation: a comparison of two manual devices Anesth Analg. 2010 Oct;111(4):922-4
One infrequently used option for refractory status epilepticus is isoflurane anaesthesia. A report of two cases demonstrates progressive MRI changes suggestive of neurotoxicity, that improved after discontinuation of isoflurane. Impossible to prove cause and effect here, since the both patients had status for weeks and were on multiple anticonvulsant medications, for example lorazepam, fosphenytoin, levetiracetam, valproate, and subsequent infusions of midazolam, pentobarbital, and ketamine. Neither patient recovered beyond a minimally conscious state. This article serves as a reminder that:
Persistent status epilepticus may be associated with a poor neurologic outcome
Some cases are extremely refractory to treatment
Isoflurane is one of many options to try when standard anticonvulsant regimens are failing
Dr WFS Sellers and colleagues describe several cases that demonstrate convincingly a protective effect of intravenous magnesium sulphate against the tachycardia produced by intravenous salbutamol in patients with asthma. This effect was observed both when magnesium was given before and when given after the salbutamol. It was seen in critically ill asthmatic patients and in a volunteer with well-controlled asthma.
Intravenous magnesium sulphate increases atrial contraction time and refractory times. It is used to treat atrial tachyarrhythmias and has a negative chronotropic and dromotropic effect. Intravenous magnesium sulphate prevents intravenous salbutamol tachycardia in asthma Br J Anaesth. 2010 Dec;105(6):869-70
