Effects of pressure- and volume-controlled ventilation on the work of breathing in cats using a cuffed endotracheal tube

Background and Aim: Mechanical ventilation is essential for supporting patients' respiratory function when they are under general anesthesia. For cats with limited lung capacity, the different effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on respiratory function remain elusive. The objective of the present study was to compare the efficacy of VCV and PCV in cats under general anesthesia using a cuffed endotracheal tube (ETT). Materials and Methods: Twelve healthy cats were randomly allocated to either a VCV or PCV group. Five tidal volumes (6, 8, 10, 12, and 14 mL/kg) were randomly applied to assess the efficacy of VCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Peak inspiratory pressures (4, 5, 6, 7, and 8 mmHg) were randomly applied to assess the efficacy of PCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Blood pressure, gas leakages, and end-tidal CO2 were recorded from 60 trials for airway control during the use of VCV or PCV. Data were compared using Fisher's exact test with a significance level of p<0.05. Results: Leakages did not differ between VCV (1/60 events) and PCV (0/60 events; p=0.500). Hypercapnia was identified when using VCV (6/60 events) less frequently than when using PCV (7/60 events; p=0.762), but did not reach statistical significance. Hypotension (mean arterial blood pressure <60 mmHg) occurred less frequently with VCV (0/60 events) than with PCV (9/60 events; p=0.003). Moreover, VCV provided a significantly lower work of breathing (151.10±65.40 cmH2O mL) compared with PCV (187.84±89.72 cmH2O mL; p<0.05). Conclusion: VCV in cats using a cuffed ETT causes less hypotension than PCV. It should be noted that VCV provides a more stable tidal volume compared with PCV, resulting in a more stable minute volume. Nonetheless, VCV should not be used in patients with an airway obstruction because higher peak airway pressure may occur and lead to lung injury.

A Case of Unanticipated difficult Intubation in a patient posted for C5-C6 Posterior Fixation

Management of a “difficult airway” poses one of the most relevant and challenging tasks for anesthesiologists. Unanticipation with difficult airway and endotracheal intubation during the conduction of general anesthesia may result in complications and fatality. We report the case of a 14 yr old boy for planned C5-C6 spine fixation under general anaesthesia. Unanticipated difficult oral intubation after three failed attempts, managed by a stylleted cuffed endotracheal tube, head up tilt of the operation table, shoulder support, cricoid pressure and rotation of the endotracheal tube anticlockwise at the glottic opening.

Cuffed endotracheal tubes in cats

A cuffed endotracheal tube may improve the airway seal in anaesthetised feline patients, compared to use of an uncuffed tube. This may improve capnography and decrease theatre pollution with volatile agents. However, two significant risks are associated with the technique. First, over-inflation of the cuff could occur, with associated iatrogenic tracheal damage; this may be prevented by use of a cuff manometer for inflation. Second, as a result of the improved seal, barotrauma may be more likely with high gas flow rates and assisted ventilation.

Treatment of Iatrogenic Subglottic Stenosis by Therapeutic Fibreoptic Bronchoscopy

Endotracheal intubation is a common procedure in intensive care unit. It still qualifies as an invasive procedure. Prolonged endotracheal intubation or intubation with cuffed endotracheal tube in a newborn or young infant is a risk factor for the development of subglottic stenosis. It usually presents with stridor in childhood. The most likely mechanism of subglottic stenosis is an injury of tracheal mucosa, with secondary scar healing that consequently leads to the development of some degree of subglottic stenosis. Depending on the degree of subglottic stenosis, patients may be asymptomatic for a long time or symptoms can occur within several weeks. The incidence of stenosis is very low if intubation lasts less than a week. Sometimes the patient may develop severe subglottic stenosis after short-term endotracheal intubation. Intubation with cuffed endotracheal tube in newborn results in pressure necrosis and sloughing followed by subglottic stenosis. This article presents a case of a patient (Baby A) who had intubation with cuffed tube which landed to airway problem and stenosis and was managed successfully by taking help from an expert pediatric pulmonologist of a neighbouring country. Journal of Armed Forces Medical College Bangladesh Vol.13(2) 2017: 64-68

Efficacy of intracuff dexamethasone in reducing the incidence of post-operative sore throat: an original article

Background: Postoperative sore throat is the most common and most distressing complaint of patients after general anaesthesia with cuffed endotracheal tube. By this study our aim was to assess the efficacy of intracuff dexamethasone in reducing the incidence of this distressing postoperative symptom.Methods: Patients were divided into two groups D and N depending on cuff filling with dexamethasone and normal saline respectively. The cuff was prefilled with dexamethasone or normal saline one hour prior to intubation to allow time for cuff to be saturated following which the cuff was deflated. General anaesthesia was administered and patients were intubated, and cuff inflated with drug according to group allocated. Patients were assessed and graded for sore throat using VAS scale both at rest and with swallowing. Assessment was done one hour, six, 12 and 24hours post operatively. Presence of hoarseness of voice and cough was assessed on a 2-point scale 0=absent and 1=present, 24hrs after surgery.Results: The incidence of sore throat at 24hours postoperative was reduced in group D than in group N. 4 patients (8%) in group D had sore throat while 27 patients (57%) in group N had sore throat at 24hours. This was statistically significant (p<0.05). The cough incidence was reduced in group D while there was no difference in incidence of hoarseness of voice between the two groups.Conclusions: Intracuff dexamethasone decreases the incidence of postoperative sore throat when compared to intracuff normal saline. Dexamethasone also reduces postoperative cough incidence but does not reduce the incidence of hoarseness of voice.