Airway obstruction due to arytenoid prolapse in a child

Mechanisms underlying hypothermia-induced cardiac contractile dysfunction

Rewarming patients after profound hypothermia may result in acute heart failure and high mortality (50-80%). However, the underlying pathophysiological mechanisms are largely unknown. We characterized cardiac contractile function in the temperature range of 15-30 degrees C by measuring the intracellular Ca(2+) concentration ([Ca(2+)](i)) and twitch force in intact left ventricular rat papillary muscles. Muscle preparations were loaded with fura-2 AM and electrically stimulated during cooling at 15 degrees C for 1.5 h before being rewarmed to the baseline temperature of 30 degrees C. After hypothermia/rewarming, peak twitch force decreased by 30-40%, but [Ca(2+)](i) was not significantly altered. In addition, we assessed the maximal Ca(2+)-activated force (F(max)) and Ca(2+) sensitivity of force in skinned papillary muscle fibers. F(max) was decreased by approximately 30%, whereas the pCa required for 50% of F(max) was reduced by approximately 0.14. In rewarmed papillary muscle, both total cardiac troponin I (cTnI) phosphorylation and PKA-mediated cTnI phosphorylation at Ser23/24 were significantly increased compared with controls. We conclude that after hypothermia/rewarming, myocardial contractility is significantly reduced, as evidenced by reduced twitch force and F(max). The reduced myocardial contractility is attributed to decreased Ca(2+) sensitivity of force rather than [Ca(2+)](i) itself, resulting from increased cTnI phosphorylation.

Effects of sympathetic stimulation during cooling on hypothermic as well as posthypothermic hemodynamic function

This experimental study was performed to explore hemodynamic effects of a moderate dose epinephrine (Epi) during hypothermia and to test the hypothesis whether sympathetic stimulation during cooling affects myocardial function following rewarming. Two groups of male Wistar rats (each, n = 7) were cooled to 15 °C, maintained at this temperature for 1 h, and then rewarmed. Group 1 received 1 μg/min Epi, i.v., for 1 h during cooling to 28 °C, a dose known to elevate cardiac output (CO) by approximately 25% at 37 °C. Group 2 served a saline solution control. At 37 °C, Epi infusion elevated CO, left ventricular systolic pressure, maximum rate of left ventricle pressure rise, and mean arterial pressure. During cooling to 28 °C, these variables, with the exception of mean arterial pressure, decreased in parallel to those in the saline solution group. In contrast, in the Epi group, mean arterial pressure remained increased and total peripheral resistance was significantly elevated at 28 °C. Compared with corresponding prehypothermic values, most hemodynamic variables were lowered after 1 h at 15 °C in both groups (except for stroke volume). After rewarming, alterations in hemodynamic variables in the Epi-treated group were more prominent than in saline solution controls. Thus, before cooling, continuous Epi infusion predominantly stimulates myocardial mechanical function, materialized as elevation of CO, left ventricular systolic pressure, and maximum rate of left ventricle pressure rise. Cooling, on the other hand, apparently eradicates central hemodynamic effects of Epi and during stable hypothermia, elevation of peripheral vascular vasopressor effects seem to take over. In contrast to temperature-matched, non-Epi stimulated control rats, a significant depression of myocardial mechanical function occurs during rewarming following a moderate sympathetic stimulus during initial cooling.

Complete upper airway obstruction after induction of anesthesia in a child with undiagnosed lingual tonsil hypertrophy

We present a case of a 9-year-old patient with previously undiagnosed lingual tonsil hypertrophy (LTH) that caused sudden and complete airway obstruction and inability to ventilate on induction of anesthesia. More frequently described in adults than in children, LTH can complicate mask ventilation, intubation or both, with the potential for catastrophic consequences.

Management der oberen Atemwege beim spontan atmenden Kind

In unconscious, spontaneously breathing and anaesthetised children, a high incidence of partial or complete airway obstruction jeopardizes sufficient oxygenation. In this situation, the most important and efficient manoeuvre is to open up the upper airway. Chin lift, jaw thrust and continuous positive airway pressure (CPAP) are proven and effective methods for opening an obstructed upper airway. In addition to these simple airway manoeuvres, different techniques of body positioning (e.g., lateral positioning or supine position in combination with the "sniffing position") are effective to improve and maintain upper airway patency.

The paediatric upper airway: anaesthetic aspects and conclusions

PURPOSE OF REVIEW

Paediatric airway problems are among the most challenging clinicians will face throughout their career. Clinicians unaccustomed to dealing with children tend to approach paediatric airway problems with a disproportionate amount of fear that is often engendered by inexperience, and this fear can interfere with performance. Understanding the differences between the infant upper airway and the airway in older children is important to properly manage the airway.

RECENT FINDINGS

Airway manoeuvres and the important tools used for airway management, such as the laryngeal mask airway, the fibreoptic bronchoscope and the new intubating fibreoptic stylets for managing the difficult paediatric airway, have been elucidated in the literature.

SUMMARY

Planning, preparation, and teamwork are essential, and must include an awareness of problems that might occur in the recovery period. Special clinical situations such as management of the child with impending airway obstruction are discussed.

The effects of common airway maneuvers on airway pressure and flow in children undergoing adenoidectomies

Obstruction of the upper airway occurs frequently in anesthetized, spontaneously breathing children, especially in those with adenoidal hyperplasia. To improve airway patency, maneuvers such as chin lift (CL), jaw thrust (JT), and continuous positive airway pressure (CPAP) are often used. In this study, we examined the comparative efficacy of these maneuvers in children scheduled to undergo adenoidectomy. Sixteen children aged 2-9 yr were anesthetized with sevoflurane. During spontaneous breathing, the flows and pressures in the mask (ma), oropharynx (op), and esophagus (es) were measured simultaneously, and maximal pressure differences during inspiration (DeltaP) were calculated. After baseline recording, CL and JT maneuvers were performed in random order without and with CPAP (5 cm H(2)O). The observed DeltaP(ma) - P(es) of 12.3 +/- 3.4 cm H(2)O at baseline decreased with all airway maneuvers (P < 0.05). This resulted from decreases of DeltaP(ma) - P(op) (P < 0.05) and DeltaP(op) - P(es) (P < 0.05) in all interventions except CL, in which DeltaP(ma) - P(op) remained similar. In contrast, significant improvements of minute ventilation and maximal inspiratory peak flow (P > 0.05) were observed only with JT (with and without CPAP). We conclude that CL may improve airway patency and ventilation, whereas JT with or without CPAP was the most effective maneuver to overcome airway obstruction in children with adenoidal hyperplasia.

IMPLICATIONS

Airway maneuvers are often used in anesthetized children to relieve airway obstruction during spontaneous ventilation. Compared with chin lift and continuous positive airway pressure, the jaw thrust maneuver was the most effective to improve airway patency and ventilation in children undergoing adenoidectomy.

Effect of airway opening manoeuvres on thoraco-abdominal asynchrony in anaesthetized children

Thoraco-abdominal asynchrony is frequently encountered during inhalation anaesthesia in children with adenotonsillar hypertrophy causing an upper airway obstruction. The study goal was to evaluate the impact of different airway opening manoeuvres on thoraco-abdominal asynchrony as a measure of airway obstruction. Thirty anaesthetized children (aged 2-8 yrs; sevoflurane 3% in 50% oxygen/nitrous oxide) were studied prior to elective adenotonsillectomy using respiratory inductance plethysmography to record ribeage and abdominal wave forms as a basis for calculation of the phase angle. Five airway situations were compared: 1) baseline (unsupported mandible); 2) chin lift; 3) chin lift combined with continuous positive airway pressure of 10 cmH2O; 4) jaw thrust; and 5) jaw thrust combined with continuous positive airway pressure of 10 cmH2O. Three children had complete upper airway obstruction at baseline and were excluded from the study. With chin lift, thoraco-abdominal asynchrony improved in three patients, worsened in three patients and was unchanged in 21 patients. Additional continuous positive airway pressure during chin lift did not markedly reduce thoraco-abdominal asynchrony (phase angle 89 +/- 43 , p = 0.33). Jaw thrust resulted in a significant decrease of the phase angle (from 106 +/- 53 at baseline to 65 +/- 49 , p < 0.01); when combined with continuous positive airway pressure, no further effect on thoraco-abdominal asynchrony was found (72 +/- 44). In anaesthetized children with adenotonsillar hypertrophy, airway opening manoeuvres have distinct effects on thoraco-abdominal asynchrony. Delivery of continuous positive airway pressure and jaw thrust can be the first airway opening manoeuvres to improve breathing patterns. Chin lift without additional continuous positive airway pressure should be used with caution in these patients because it may convert partial into almost complete airway obstruction.

Arytenoid prolapse as a consequence of cricotracheal resection in children

Cricotracheal resection (CTR) is a technique introduced comparatively recently for treating severe laryngotracheal stenosis in children. The recognized complications of CTR include recurrent laryngeal nerve damage, anastomotic dehiscence, and restenosis. We describe a further complication of CTR, namely, prolapse of the arytenoid cartilage. The presentation may be late, with symptoms of shortness of breath on exertion and nocturnal stertor with a poor sleep pattern, or the prolapse may be an asymptomatic incidental finding. The diagnosis is performed with flexible nasopharyngoscopy with the patient unanesthetized, or with rigid endoscopy with the patient lightly anesthetized and spontaneously ventilating. The affected arytenoid cartilage is noted to prolapse anteriorly and medially with inspiration, partly obstructing the airway. If treatment is required, endoscopic laser partial arytenoidectomy is effective. In a series of 44 children who underwent CTR, 20 were noted to develop arytenoid prolapse after operation. Twelve were asymptomatic, and 8 required laser arytenoidectomy, 2 of whom now require continuous positive airway pressure for moderate supraglottic collapse.