Endoscopic examinations (Proceedings)
Endoscopic use is increasingly utilized in small animal hospitals because endoscopic tools have great utility in the evaluation of patients with respiratory, gastrointestinal and genitourinary tract disease. Many practitioners are becoming comfortable with endoscopic examinations and are acquiring the equipment necessary for such examinations. These notes will present an overview of the nursing support services often needed to accomplish flexible endoscopic examinations in small animal patients with the focus on rhinoscopy/bronchoscopy, gastrointestinal endoscopy, and cystoscopy. Emphasis will be placed on assembling the materials that facilitate examination and sample collection, patient anesthesia and patient positioning. While not an element of this presentation, those nurses using endoscopes should be familiar with their handling and cleaning to limit endoscope damage and promote patient safety. Rigid endoscopic examinations (laparoscopy, thoracoscopy) will not be discussed.
Prior to patient anesthesia, the examination area is prepared by assembling the endoscopic equipment. Other items that are often needed and should be handy include syringes, red-rubber catheters that can be placed in the nasal cavity for nasal flushes and that can be used to lavage and suction the nasal cavity, microscope slides for cytology preparations, biopsy instruments, formalin, and needles that can be used to aspirate solutions or tease small tissue pieces from biopsy forceps. Pre-warmed bottles or vials of 0.9% saline that do not contain bacteriostatic agents should be readily available as well for flushes or lavages if submission of samples for microbiologic cultures is anticipated (most commonly as an adjunct to bronchoscopic examinations). A vacuum/suction system with variable levels of suction is useful for aspiration of blood and mucus can aid rhinoscopic examination in patients with spontaneous or iatrogenic (which commonly occurs during nasal examination) epistaxis or large volumes of mucus in the airways. Gauze sponges (non-sterile is fine) are also helpful for removing nasal exudates, and can help control bleeding when applied to the nostril. Cytology brushes can be useful for sampling lesions. Having on hand an assortment of catheters (polypropylene, Foley) suitable for placing in the nasal cavity of dogs suspected of having nasal aspergillosis allows the rhinoscopic examination to proceed to a treatment session if owners are inclined to pursue topical therapy with an anti-fungal solution. While not necessarily needed for the endoscopic examination of the nasopharynx, a spay hook can be useful to retract the soft palate rostrally if lesions dorsal to the soft palate are observed; soft palate retraction may allow acquisition of a better biopsy that can be obtained through the retroflexed endoscope. Pulse oximeters are very helpful patient monitoring tools.Patients that are candidates for rhinoscopy/bronchoscopy are routinely anesthetized; administration of narcotics as pre-medications can help reduce sneezing and coughing associated with introduction of the endoscope into the nasal passages and trachea. Some clinicians prefer neuromuscular blocking agents to limit the gag reflex that can be seen in some patients at otherwise appropriate levels of anesthesia, but their use will mandate short-term ventilatory support. Animals undergoing rhinoscopy may also sneeze at otherwise adequate surgical planes of anesthesia, and it is thus not unusual in the author's practice to see these patients administered additional boluses of short-acting narcotics (often fentanyl) as needed until rhinoscopy is completed.
Depending on the size of the bronchoscope and the patient, the endoscope may be advanced into the trachea through an endotracheal tube; oxygen may be insufflated through a biopsy channel if present in the endoscope. Adapters that allow passage of the bronchoscope through one opening while maintaining a connection to the anesthetic tubing can be used in some animals. Recall that with an endoscope in the lumen of the endotracheal tube and trachea that the work of breathing for the patient increases, so monitoring should not become lax when using this type of set-up. The bronchoscopic examination is often conducted in segments dictated by the anesthetic depth and oxygen needs of the patient (as determined by SpO2 values on the pulse oximeter). If the bronchoscope cannot be passed through an endotracheal tube, the patient will need to be extubated and intubated repeatedly until the examination and sample acquisition have been completed. Intravenous anesthesia (e.g. propofol infusions) can help with anesthetic depth in patients undergoing bronchoscopic examination.
For rhinoscopy, the patient is usually positioned with the head supported on a roll of towels, or other soft support. An oral speculum is placed before retroflex views of the nasopharynx are obtained so that the endoscope is not inadvertently bitten when the patient is stimulated. Patients undergoing bronchoscopy are typically placed in sternal recumbency for initial examination and then positioned in an appropriate lateral recumbency (diseased side down) for alveolar lavage. Aliquots (up to 5 ml/kg) of warm saline can be passed to the endoscopist for alveolar lavage. Lavage fluid can then be placed in tubes to submit for cytologic examination, culture, etc.