Inhalotherapy currently represents the main method for treating respiratory disorders, because it has the benefit of allowing drugs to be delivered directly to the large surfaces of the tracheo-bronchial tree and alveoli.
A 76 year old female patient presented for vitreo retinal surgery (vitrectomy, ILM peeling, endolaser). She was known for hypertension, ischemic heart disease, underwent CABG 8 years ago and suffered from interstitial lung disease for past 5 years. She had undergone bilateral cataract extraction under topical anaesthesia else where 10 years ago. Her main drug prescription included a calcium channel blocker, anti platelets, broncho dilator inhaler and multivitamins.
Her laboratory investigations were unremarkable. ECG showed old inferior wall ischemic changes. ECHO read as good LV function with EF of 60%.
Vital parameters were normal. Other systemic examination was also normal.
Respiratory system on auscultation showed bilateral rhonchi and crepitations. The room air oxygen saturation was 93-94%. Hence a broad spectrum antibiotic (Amoxicillin and potassium clavilunate) was started and continued for 5 days.
But the lung signs persisted after the course of antibiotic. As this was the only seeing eye, she was insisting on surgery. She was scheduled for surgery under local anaesthesia.
On the morning of surgery patient was requested to take all her regular medications including broncho dilator inhaler. In the preoperative receiving area patient was reassured and nebulized with 50 mgs of ketamine mixed with 4ml of distilled water. At the end of nebulisation, patient confirmed that she was feeling much better and her oxygen saturation also improved to 97-98% in room air. Auscultation of respiratory system showed absence of rhonchi though a few basal crepitations persisted.
Patient was wheeled into OR and after connecting ECG, NIBP, Spo2, a sub-tenon block was given using 5 ml of 0.5% Bupivacine. The duration of the surgery was around two hours. The patient was comfortable for the entire duration. Sedation was avoided considering her lung condition. The oxygen saturation maintained between 97-98% throughout the procedure. Postoperatively patient was asked to continue her regular medications.
Intravenous administration of ketamine is known to cause bronchial smooth muscle relaxation. Furthermore, increasing evidence suggests that the anti inflammatory properties of ketamine may protect against lung injury. However, ketamine inhalation might yield same or better results at higher airway and lower plasma concentrations of ketamine for the treatment of broncho constriction.
Ketamine acts as a broncho dilator probably by two different mechanisms. Firstly via a central effect inducing catecholamine release thereby stimulating beta 2 adrenergic receptors, resulting in broncho dilatation. Secondly, via inhibition of vagal pathways to an anticholenergic effect directly on bronchial smooth muscle (11560199).
Inhaled drugs play an important role in asthma management, as many of the beta adrenergic and anticholenergic broncho dilators, corticosteroids and non steroidal anti inflammatory agents currently used in the treatment of acute asthma are administered as inhaled gases or aerosols (10608428). Although steroids and beta agonists form the mainstay of asthma therapy,the symptoms in some asthmatics are poorly controlled with these drugs and their therapeutic benefits may be outweighed to some degree by their undesirable side effects (http://journals.lww.com/clinpulm/Abstract/2002/05000/Recent_Concepts_in_the_Pathogenesis_and_Treatment.1.aspx).
Thus ketamine apart from its anaesthetic properties is also proving beneficial in some refractory COPD cases in controlling the symptoms.(12840699)