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.

Rhinoscopy/bronchoscopy

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.

Gastrointestinal endoscopic examination

Prior to gastrointestinal (GI) examination, the endoscope and biopsy forceps, and possibly a cytology brush should be collected and the endoscope set up. Other materials commonly needed during the course of GI endoscopic examinations include an oral speculum, formalin jars, needles to tease biopsies from biopsy forceps, and microscope slides (for squash preparations of biopsies if desired). Some clinicians prefer to mount their biopsy samples on sponges that can be placed in tissue cassettes designed for such purposes, or placed on pieces of wood tongue depressors. Some laboratories prefer to simply have tissue pieces loose in the formalin jar with the histology technician orienting the biopsy sample for sectioning. It is advisable to check with the pathology laboratory that will be processing the samples (make sure to point out that these are endoscopic biopsies) beforehand to make sure that the samples are handled according to their preferences. If placement of feeding tubes (esophagostomy or percutaneous endoscopic gastrostomy- PEG- tubes) is anticipated, the necessary supplies should be readily available for tube placement.

Patients undergoing GI examinations (gastroduodenscopy, colonoscopy) need appropriate periods of fasting before anesthesia and examination. For patients undergoing upper GI examinations, an overnight (12 hour) fast is usually sufficient; some clinicians advocate fasting for at least 48 hours to as much as 72 hours for patients undergoing colonoscopy. A number of lavage solutions exist for cleansing the intestinal tract, in particular the colon prior to colonscopy, and most clinicians that use them tend to have their favorites; some clinicians will prefer administration of multiple enemas to prepare the colon for examination. The properly prepared patient is anesthetized with standard agents except that patients that will have upper GI examinations are not pre-medicated with opioids as these drugs tend to increase the tone of the pyloric sphincter and can make duodenal intubation more challenging. At WSU, we withhold opioids until after the duodenum has been intubated (and we try to intubate the duodenum early in the course of the endoscopic examination) if there are other reasons for the patient to receive opioids.

Patients undergoing either gastroduodenoscopy or colonoscopy are positioned in left lateral recumbency to move fluid out of the antrum and pylorus, or out of the ileocecal colic area, to facilitate examination of these segments of the GI tract. When the clinician is ready to place the endoscope into the oral cavity, an oral speculum should be placed to prevent accidental damage to the endoscope should stimulation provoke a bite or jaw movement. Depending on the skill of the endoscopist, nursing staff may be asked to help advance and retract the endoscope through the GI tract as needed, or to assist in acquisition of biopsies, so familiarity with how the biopsy forceps operate can be useful. The nurse may also be asked to pinch the anal opening closed around the endoscope during the first part of colonoscopic examinations to facilitate air insufflation into the colon, needed to visualize the lumen before the endoscope is advanced.

Cystoscopy

Prior to patient examination, endoscopic equipment is gathered. For cystoscopy, sterile gloves are worn by the endoscopist, and a fenestrated drape, or drape that can be fenestrated, will also be needed. As with other endoscopic procedures, formalin jars, needles to tease biopsies from forceps and glass slides should be available. In addition, a bag (or more) of sterile isotonic solution such as lactated Ringer's or normal saline that has been warmed to body temperature and a fluid administration set will be needed for irrigation during the examination.

For cystoscopic examinations, the patient is routinely anesthetized- there are usually no special anesthetic considerations for patients undergoing typical lower urinary tract examinations. The female patient can be positioned in dorsal, ventral, or lateral recumbency according to clinician preference; male patients are often positioned in lateral or dorsal recumbency. The patient's pelvis (females) is usually positioned toward the edge of the examination table and the rear legs relaxed in a frog-leg configuration (dorsal or ventral recumbency). A movable stool for the endoscopist is often appreciated for examination of patients in these positions. The perivulvar area is clipped and a light Betadine or nolvasan solution lavage of the vestibule may be done to remove debris. The fenestrated drape is placed over the field and clipped in place if needed. Irrigation fluid is hanged above the level of the urinary bladder and available to the cystoscopist. An extension set can be attached to the outflow port of the cystoscope to direct irrigation solution into a bucket or large bowel. Towels placed on the floor help with the inadvertent spray or splash of irrigation solution.

Summary of the general needs of the nursing staff during endoscopic examinations

The nursing staff can play key roles in the preparation of equipment, and patient preparation. A critical job that is likely to be asked of the nursing staff is anesthetic monitoring during the endoscopic examination. Attention to pulse oximetry values -a drop in the SpO2 to below 80% during bronchoscopic examination mandates withdrawal of the endoscope and oxygen supplementation until values have returned to baseline- and attention to anesthetic depth are critical to successful endoscopic examinations. Some manipulations of the endoscope and acquisition of biopsy samples may also be helpful to the clinicians performing endoscopic examinations. Lastly, cleaning and care of the endoscopic equipment as outlined by the manufacturers instructions is also likely to fall into the hands of the hospital's nursing staff. A list of supplies commonly needed for all endoscopic procedures is provided below, and the collection can be modified to best suit individual clinician preferences. Keeping an "endoscopic" kit (e.g. tackle box or storage system) can help keep things organized and ensure consistent availability of commonly needed supplies.

Common items needed for small animal endoscopic procedures

• Oral speculum

• Needles

• Syringes (6, 12, 20, 35 and 60 ml syringe tip recommended)

• Saline solution

• Gauze sponges

• Microscope slides

• Formalin jars

• Labels

• Red-top tubes (for submission of samples for cytology)

• Assortment of catheters

o Red-rubber

o Feeding tube catheters

o Foley catheters (for nasal aspergillosis topical therapy)

• Bottles or bags of physiologic solutions (LRS. 0.9% saline) and administration sets for lavage

• Towels

• Pads for positioning (rhinoscopy); rolled towels can also serve this purpose

• Endoscopic equipment

o Endoscopes

o Viewing monitors and processors

o Suction tubing

o Cytology brush

o Biopsy forceps

o Cleaning brush and cleaning solutions