Gastroparesis

An empty-stomach history proves nothing here - gastric emptying is unpredictable and may not improve with more waiting time, so the history alone will not tell you what is in the stomach. Look instead of assuming.

Gastric ultrasound answers the question - scan the antrum in the parasagittal plane, supine and then in right lateral decubitus, measuring cross-sectional area at the level of the aorta rather than the IVC (measuring at the IVC underestimates volume and gives false negatives). Estimated clear-fluid volume in mL = 27 + (14.6 x CSA) - (1.28 x age). Under 1.5 mL/kg is baseline secretions and low risk; above that is a full stomach, and any solid or thick liquid is a positive scan regardless of volume.

Positive scan, elective case - cancel or postpone for solids, thick liquids, or clear fluid over 1.5 mL/kg.

If the case has to proceed - full aspiration precautions. Either give no sedation at all so airway reflexes stay intact, or protect the airway with RSI and an endotracheal tube. Decompress the stomach with a nasogastric or orogastric tube before induction or right after intubation.

Glucose control is motility control - acute hyperglycemia itself slows gastric emptying and is reversible with better control, while the damage from chronic hyperglycemia is not. Tight glycemic control is part of preop optimization, and expect erratic glucose because carbohydrate absorption tracks with emptying speed.

Read the medication list - opioids and anticholinergics slow the stomach further, and cannabinoids delay emptying. Metoclopramide is the FDA-approved prokinetic for acute and recurrent diabetic gastroparesis: 10 mg orally four times daily, 30 minutes before each meal and at bedtime, maximum 40 mg per day, with a reduced 5 mg dose in the elderly and in hepatic or renal impairment. Erythromycin is used off-label through motilin receptors, but tachyphylaxis limits it to about four weeks at a stretch.

GLP-1 agonists compound the problem - the 2024 multisociety guidance (ASA with the gastroenterology and bariatric societies) has most patients continue their GLP-1 before elective surgery, with a risk-based, shared decision among the patient, prescriber, proceduralist, and anesthesia team. Highest-risk patients take a liquid diet for 24 hours beforehand. If the patient has GI symptoms, or the drug was not held as advised, proceed with full-stomach precautions or scan the stomach.

Metoclopramide has teeth - the boxed warning is tardive dyskinesia, a potentially irreversible movement disorder whose risk climbs with treatment duration and total cumulative dose. It is contraindicated in anyone with a history of TD, treatment should stay under 12 weeks, and other extrapyramidal symptoms (acute dystonia, akathisia, parkinsonism) and neuroleptic malignant syndrome are on the label too. Avoid it in Parkinson disease and think twice before stacking it with droperidol or another dopamine antagonist.

Volume and electrolytes first - repeated vomiting and poor intake leave these patients dry with electrolyte and nutritional deficits. Correct fluid and electrolyte deficiencies before induction; some are malnourished enough to be on jejunostomy feeds or parenteral nutrition.

Diabetic gastroparesis rarely travels alone - it clusters with long-duration type 1 diabetes and reflects autonomic neuropathy, so expect the rest of the autonomic picture and plan for a labile blood pressure response to induction.

Gastroparesis is delayed gastric emptying in the absence of mechanical obstruction. Normal emptying needs coordinated sympathetic and parasympathetic input, intrinsic enteric neurons, the interstitial cells of Cajal that act as gastric pacemakers, and gut smooth muscle; gastroparesis follows damage at any of those levels, with loss of interstitial cells of Cajal a recurring finding. In one tertiary series the causes broke down as 36% idiopathic, 29% diabetic, 13% postsurgical, 7.5% Parkinson disease, and 4.8% collagen vascular disease, with a female-to-male ratio near 4:1. Patients report nausea, vomiting, early satiety, postprandial fullness, bloating, and upper abdominal pain, and the vomitus characteristically contains food eaten hours earlier.

That last detail is the perioperative point: a stomach that empties unpredictably means a fasted patient can still be a full stomach.