Ketamine respiratory depression is considered to be the ideal anesthetic for asthmatic patients because it decreases the risk of bronchospasm during induction of anesthesia and preserves the pulmonary vasoconstriction reflex to hypoxia.
It does not produce significant depression of ventilation. The ventilatory response to carbon dioxide is maintained during ketamine respiratory depression anesthesia.
The respiratory depression with Ketamine in minimal and hence it is a good drug for sedation.
Breathing frequency typically decreases for initial few minutes after administration of ketamine. Apnoea, however, can occur if the drug is administered rapidly IV or in excess dose or an opioid is included in the preoperative medication.
There is high incidence of arterial desaturation observed immediately after induction of anesthesia with intravenous ketamine however relieved with oxygen supplementation for initial 10-15 minutes in contrast to volatile anesthetic agents, ketamine anesthesia has a sparing effect on intercostal muscle activity, which may explain the maintenance of functional residual capacity.
Upper airway skeletal muscle tone is well maintained, and upper airway reflexes remain relatively intact after administration of Ketamine respiratory depression .
Increased secretions from salivary and tracheobronchial mucous glands occur after IM or IV administration of ketamine, necessitating the use of an antisialagogue, preferably glycopyrrolate, to be included in the preoperative medication.