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Pharmacology—with its great number and variety of drugs and their potential for interaction—poses one of the biggest challenges for most surgical technology students.
What’s the best way to learn and remember pharmacology? The best method we have found is simple repetition paired with putting yourself in the patient’s shoes. If you’ve had surgery, recall your experiences, and if you haven’t, just imagine the experience.
As you know, there are three phases in surgical case management:
• Preoperative
• Intraoperative
• Postoperative
There are also four phases of general anesthesia, during which specific tasks are performed and certain medications are administered (Table 5.1).
Let’s track a patient through a surgery, examining the medications that may be administered, depending on the purpose of the surgery.
Preoperative Drugs
These drugs are administered in the holding area to prepare the patient physically and psychologically for surgery.
Hydration
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A patient may be given any of several intravenous (IV) solutions to help ensure homeostasis and safe anesthesia, depending on the patient and the surgery.
0.9% Sodium Chloride (NaCl) (Isotonic)
This is a salt solution.
• Agent of choice for fluid replacement or simple hydration
• Used for the transfusion of blood products because it does not induce hemolysis (destruction) of blood cells
Dextrose (D)
Dextrose is a sugar solution.
• Used to hydrate the surgical patient, spare body protein (by providing a source of energy), and enhance liver function.
• Used for the temporary treatment of circulatory insufficiency and shock due to hypovolemia in the absence of plasma extender
• Also used for early treatment, with plasma, of fluid loss due to burns
• Not used in the transfusion of blood products; causes hemolysis of blood cells
Lactated Ringer’s Solution (LR)
This salt solution is also referred to as Ringer lactate (RL).
• Replenishes the patient’s electrolytes
• Used for rehydration to stimulate renal activity
• Also used to replace fluid lost from burns or severe diarrhea
• Not advised for patients with liver disease, Addison disease, severe pH imbalance, shock or cardiac failure
Ionosol B
This solution is also known as MB&T.
• Used for maintenance and replacement of electrolytes
• Provides water, electrolytes, and carbohydrates to cover hydration, insensible water loss, and urine production
PlasmaLyte or Isolyte E
These solutions are used to treat massive loss of water and electrolytes.
• Often used in the setting of uncontrolled vomiting or diarrhea, shock, burns, or multiple blood transfusions
Physical and Psychological Preparation for Surgery
Sedatives
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These medications relieve anxiety; some produce mild drowsiness and may have amnestic and antiemetic effects. The main adverse effect is respiratory depression.
Benzodiazepines
At low dosages, these drugs exert an anxiolytic effect (relief of anxiety); at higher doses they induce sedation and anterograde amnesia.
• Diazepam (Valium)
• Lorazepam (Midazolam)
• Midazolam (Versed) (most commonly used)
Gastric Agents
Nil per os (nothing by mouth; NPO) status is instituted for a patient undergoing elective surgery, but there will still be acidic gastric secretions in the stomach that may be aspirated if the patient vomits during the induction of anesthesia. This could in turn result in the development of a condition known as aspiration pneumonitis.
A patient who must undergo emergency surgery is at even greater risk because there has been no fasting to empty the stomach, increasing the likelihood of vomiting of food or secretions and therefore increasing the risk of aspiration.
Certain conditions put patients at even higher risk for aspiration, even when NPO status is instituted:
• Gastrointestinal obstruction
• History of gastrointestinal reflux disease
• Diabetes
• Obesity
• Labor
• Scheduled cesarean section
Gastric agents commonly used in surgery
These medications are generally used to control stomach acid.
• Antacids
• Sodium citrate with citric acid (Bicitra): This drug given before surgery to neutralize the acidity of stomach contents by causing them to be metabolized to sodium bicarbonate.
• H2-receptor antagonists
• Cimetidine (Tagamet)
• Famotidine (Pepcid)
• Ranitidine (Zantac)
• Proton pump inhibitors
• Protonix IV (reduces gastric acid in 20 minutes)
• Antiemetic and gastrointestinal prokinetics.
• These agents are administered before surgery to reduce nausea and minimize the possibility of postoperative nausea and vomiting (PONV) in at-risk patients:
• Preadolescents
• Obese people
• People with diabetes
• People with a history of gastroesophageal reflux disease
• Women in labor or undergoing scheduled cesarean section
• Patients receiving opioids, barbiturates, or etomidate
• Patients with gastrointestinal obstruction
• Antiemetic drugs include:
• Metoclopramide (Reglan)
• Droperidol (Inapsine)
• Ondansetron (Zofran)
Analgesics
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Pain relievers are often given before surgery to trauma patients and to patients who will require the insertion of invasive monitors before surgery. The most commonly administered analgesic agents are opioids (narcotics)—morphine, heroin, and other drugs derived from the opium poppy (shown here), as well as synthetic versions of these drugs.
Commonly administered analgesics
• Morphine (natural opioid)
• Meperidine (Demerol; synthetic opioid)
• Fentanyl (Sublimaze; synthetic opioid)
Facts to remember
• These agents induce analgesia and mild sedation; this helps the anesthesiologist reduce the amount of anesthesia needed for the surgical procedure.
• Nausea and vomiting is sometimes seen with these agents.
• Slowed respiration and intestinal motility is expected with these drugs. (When there is slowed respiration, it is monitored with a pulse oximeter).
• Opioids are contraindicated in patients undergoing ambulatory surgery because of the prohibitively intensive monitoring they require.
Anticholinergics
These agents block the action of neurotransmitter acetylcholine, inhibiting the transmission of parasympathetic nerve impulses.
• Not routinely used but are indicated in specific instances to inhibit mucous secretions in the respiratory and digestive tract (antisialagogue effect)
• Commonly used anticholinergics:
• Atropine
• Glycopyrrolate (potent antisialagogue effect)
• Scopolamine (three times as potent as antisialagogue effect)
Antibiotics
These drugs, also known as antimicrobial agents, are used to prevent and to treat infections caused by pathogenic (disease-causing) microorganisms. There are six major groups of antibiotics that every student should remember, each with a different means of combating microorganisms (Fig. 5.1):
Aminoglycosides
This class of antibiotics is derived from various strains of the Actinomyces bacteria genus.
• Interfere with protein synthesis by binding to bacterial ribosomes, meaning that there are bactericidal and narrow spectra of action
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