The Numbers in the Syringe

The rhythm above continues, but it no longer governs everything. On the second floor of Blegdam Hospital, in a room converted from storage in late August, another rhythm has begun—quieter, more deliberate, and no less decisive.

Poul Astrup stands at a bench that runs the length of the narrow space. The window behind him faces north, away from the sun, which is how he wants it. Light changes temperature; temperature changes chemistry. He is thirty-seven, a specialist in clinical chemistry who has spent his career measuring what the body reveals when pressed precisely enough. Now he presses it in a way no one has tried before. On the bench before him sits a pH meter, its electrode glassware delicate as a wineglass, its calibration dependent on solutions he prepares each morning. Beside it, the Van Slyke apparatus occupies its own wooden stand: a glass chamber, mercury manometer, stopcocks, rubber tubing coiled like surgical intestine. The machine measures carbon dioxide by extracting it from blood under vacuum, quantifying the gas that Ibsen believes is killing the patients upstairs.

Astrup’s problem is time. Arterial blood, once drawn, begins to change immediately. The cells continue to metabolize, consuming oxygen, producing carbon dioxide, shifting the pH. A sample that sits for ten minutes is not the same blood that flowed from the patient’s artery. For his numbers to mean anything, he must complete the measurement before the chemistry drifts. This means drawing the sample, carrying it down the stairs, and beginning the analysis within a window that closes faster than the elevator travels.

He has developed a system. The medical students squeeze their bags in six-hour shifts; the laboratory technicians, borrowed from other departments, run samples in relays. Astrup himself works twelve, sometimes sixteen hours, sleeping on a cot in the adjacent room when the workload permits. He is not a clinician. He does not touch the patients except to draw blood. What he provides is translation: the conversion of physiological crisis into numerical fact.

The needle enters the radial artery at an angle of thirty degrees. Astrup can feel the pulse against his fingertip, the artery’s resistance, then the give as the bevel penetrates the wall. Blood fills the syringe under its own pressure, dark and oxygenated, carrying the evidence he needs. He withdraws, presses cotton to the puncture site, and is already moving toward the door. The sample warms in his hand. In the stairwell, he takes the steps two at a time, not running—running jostles the syringe, introduces bubbles, ruins the measurement—but walking with the urgency of a man carrying something perishable.

The pH meter requires three minutes to stabilize. The Van Slyke, for carbon dioxide content, takes eight. Oxygen saturation he estimates from these values using the dissociation curves he has memorized, refined, committed to graph paper that now covers one wall of the laboratory. The curves are his own contribution, worked out in the weeks since Ibsen’s first success with Vivi Ebert. They allow him to predict oxygen content from pH and CO2 without a separate measurement, saving precious minutes. When he presents his data to the clinicians, he does not mention the hours of calculation behind each number. The numbers must appear authoritative, inevitable, as if they had always existed and he merely discovered them.

The first results confirm what Ibsen suspected. The patients with bulbar polio, the ones whose respiratory muscles have failed, show carbon dioxide tensions far above normal: sixty, seventy, sometimes ninety millimeters of mercury where thirty-five to forty-five would be expected. Their blood is acidotic, pH dipping below 7.2, approaching the threshold where cellular enzymes cease to function. These are the patients who die in the iron lungs, who drown in their own saliva, whose organs shut down not from the virus itself but from the chemistry of asphyxiation. The numbers make the mechanism visible. Astrup writes them in a ledger with a steel-nibbed pen, each entry dated to the minute, each sample coded to the patient whose bed number he does not know.

But confirmation is not the purpose. Ibsen has already proved his hypothesis on Vivi Ebert, already demonstrated that manual ventilation can reverse the acidosis. What Astrup provides is calibration. The students squeeze their bags at rates they judge by instinct, by the visible rise and fall of the chest, by the fatigue in their own hands. Astrup’s measurements tell them whether their instinct is correct. A patient ventilated too slowly accumulates CO2; ventilated too rapidly, she loses too much, the blood becomes alkalotic, the hemoglobin binds oxygen too tightly to release it to the tissues. There is a narrow window, and Astrup’s numbers define its edges.

He begins to post results on a board outside the laboratory. Patient numbers, times, pH, CO2, recommended ventilation rate. The students read them during shift changes, adjust their technique, return for the next measurement to see if they have succeeded. The feedback loop is clumsy, slower than ideal, but it exists. For the first time in the history of respiratory care, treatment is guided by real-time biochemical monitoring. The hand that squeezes the bag and the mind that interprets the chemistry are separated by two floors and a stairwell, but they are connected by numbers that both can read.

The laboratory fills with equipment borrowed from other departments, purchased on emergency requisition, improvised from available materials. Astrup adapts a Warburg apparatus, designed for tissue metabolism studies, to measure oxygen consumption in blood samples. He rigs a thermostat from a poultry incubator to maintain constant temperature during analysis. The pH meter, temperamental in the best conditions, requires daily calibration against buffer solutions he prepares in batches, testing each against the previous day’s standard to detect drift. He keeps a log of every calibration, every failure, every adjustment. The discipline is tedious and essential. If his numbers are wrong, the patients die. If his numbers are doubted, the entire enterprise collapses.

Skepticism persists in the senior staff. The head of the medical department, trained in an era when laboratory medicine was ancillary to clinical judgment, views Astrup’s board with visible reservation. The numbers contradict what the iron lung manufacturers claim, what the textbooks describe, what experience in previous epidemics suggested. A physician who has watched patients die in negative-pressure machines for twenty years does not easily accept that the problem was mechanical inadequacy rather than viral virulence. Astrup does not argue. He continues to draw blood, to run samples, to post results. The numbers accumulate. The patients who receive ventilation rates adjusted to his specifications show improved pH, reduced CO2, prolonged survival. The correlation is not perfect—other factors intervene, the disease has its own course—but it is consistent enough to compel attention.

By mid-September, the laboratory is processing fifty samples daily. Astrup has trained two technicians to assist with the routine measurements, reserving the complex analyzes for himself. The technicians work in twelve-hour shifts, matching the students’ schedule, so that a sample drawn at any hour can be processed without delay. The system is fragile, dependent on individuals who cannot be replaced, but it functions. Each day, the ledger grows thicker. Each day, the numbers define more precisely the relationship between manual effort and physiological outcome.

The measurement of oxygen presents special difficulties. The Van Slyke apparatus quantifies carbon dioxide with reasonable accuracy, but oxygen requires additional steps, additional time. Astrup works out an indirect method, using the dissociation curve of hemoglobin, the known relationship between pH and oxygen binding, to calculate saturation from the values he can obtain quickly. The calculation is approximate, vulnerable to individual variation in hemoglobin concentration, but it is better than guessing. He validates it against direct measurements on selected samples, refines the constants, improves the fit. The curve on his wall grows more complex, more accurate, more specific to the population he is studying.

He begins to notice patterns. Patients with similar CO2 levels respond differently to the same ventilation rate, suggesting variation in metabolic rate, in airway resistance, in the distribution of air within the lungs. He adds a column to his ledger: clinical course. Recovery, death, transition to spontaneous breathing. The correlation between early blood gas values and eventual outcome is strong enough to be useful, weak enough to remind him that numbers describe only part of the story. A patient with moderately elevated CO2 might die; another with worse values might survive. The virus, the immune response, the complications of immobility and infection—all operate independently of the respiratory parameter he can measure.

But the parameter he can measure is the one the students can control. This is the practical significance of Astrup’s work, the transformation it effects in the ward above. Where the early days of manual ventilation were governed by trial and error, by the visible signs of cyanosis or consciousness, the September regimen is increasingly numerical. A student receives a patient with a posted pH of 7.18, CO2 of 78, recommended rate of 24 breaths per minute. She squeezes, counts, adjusts her rhythm to the specified tempo. Four hours later, a new sample, new numbers, new instructions. The process is mechanical, repetitive, apparently inhuman. It is also, by the available evidence, more effective than the intuitive approach it replaces.

The laboratory itself becomes a site of pilgrimage. Physicians from other hospitals, other cities, other countries write to request information, visit to observe the methods, return to attempt replication in their own institutions. Astrup receives them between measurements, explains his equipment, lends copies of his curves, warns about the sources of error he has identified. Some visitors are convinced; others depart skeptical, committed to the technologies and theories they already possess. The epidemic in Copenhagen is exceptional in its scale, its resources, its desperation. What works here may not transfer. Astrup acknowledges the limitation without accepting it as decisive. The numbers are what they are. The interpretation is open.

Within Blegdam, his authority grows in proportion to the data he produces. When a patient’s condition deteriorates without obvious cause, the attending physician requests blood gases. When a weaning attempt fails, Astrup’s pre- and post-measurements define the physiological basis. When disputes arise about the adequacy of ventilation, the numbers settle the argument. This is not how hospital hierarchies are supposed to function. The laboratory service is traditionally subordinate to the clinical departments, providing information on request, not directing therapy. Astrup has inverted the relationship, or perhaps the emergency has inverted it for him. The patients need something only his measurements can provide. The physicians need the patients to survive. The institutional resistance dissolves in the face of demonstrated utility.

The technical challenges do not diminish. Arterial puncture in children requires skill that takes weeks to acquire; in adults with peripheral shutdown, the pulse may be impalpable, the artery inaccessible. Astrup develops alternative sites, the femoral artery, the dorsalis pedis, each with its own risks and limitations. Contamination of samples with venous blood, with air bubbles, with tissue fluid from traumatic puncture produces spurious results that must be recognized and discarded. He trains himself to detect the visual signs: color, viscosity, the pattern of filling in the syringe. Experience becomes its own form of measurement.

The equipment fails. The pH meter develops a mysterious drift that resists recalibration; Astrup traces it to a cracked reference electrode, replaces it with a spare that had been intended for another purpose. The Van Slyke mercury seal leaks; he repairs it with dental cement borrowed from the oral surgery department. Each failure is a crisis, each repair a reprieve. There is no redundancy, no backup system, no possibility of sending samples to an outside laboratory. The measurement must happen here, now, with what is at hand.

By the end of September, the mortality figures have begun to shift. The patients with bulbar polio, who had faced death rates exceeding 90 percent in the negative-pressure machines, are now surviving at rates that approach 80 percent. Positive pressure ventilators reduced mortality in bulbar patients from 90% to 20%. The improvement cannot be attributed solely to Astrup’s measurements; other factors operate, including the selection of patients who reach the ward, the prevention of secondary infection, the sheer accumulated experience of the students and physicians. But the blood gas monitoring is integral to the system that produces these outcomes. Without it, the manual ventilation would remain artisanal, uncalibrated, dependent on individual judgment at each bedside. With it, the response becomes reproducible, teachable, improvable.

Astrup does not celebrate. The ledger shows deaths as well as survivals, patients whose numbers never corrected despite optimal ventilation, whose acidosis progressed to cardiac arrest, whose CO2 fell but whose oxygen remained inadequate, indicating pulmonary complications beyond respiratory muscle failure. The virus is not defeated. The measurement only defines the battlefield more precisely. He continues to work his sixteen-hour days, to sleep on the cot, to wake for samples drawn in the night. The rhythm of the laboratory is different from the rhythm of the ward—deliberate where that is urgent, analytical where that is physical—but it is equally relentless.

The students begin to request specific measurements. A patient whose chest compliance seems to change, whose resistance to ventilation increases, wants to know whether the blood gases confirm his impression. A student who has found a rhythm that feels effective seeks numerical validation. The interaction becomes collaborative, the laboratory and the ward exchanging information in both directions. Astrup accommodates what he can, prioritizing by clinical urgency, maintaining the systematic collection that underlies his curves and correlations. The individual request and the population study pull in different directions; he manages the tension by working longer hours.

October approaches. The epidemic continues, though at reduced intensity. The first students begin to return to their interrupted studies, replaced by new volunteers who require training in techniques the veterans have refined. The laboratory processes its thousandth sample. Astrup begins to draft a report, describing the methods, presenting the data, arguing for the significance of what has been demonstrated. The writing proceeds slowly, interrupted by ongoing measurements, by consultations, by the administrative demands of a department that has grown from one man to a team of five. He writes in Danish, planning a subsequent English version for international circulation. The story must be told precisely, without exaggeration, with full acknowledgment of limitations and uncertainties. Credibility depends on restraint.

The numbers in the syringe have become something more than numbers. They are the interface between the manual labor of ventilation and the physiological reality it addresses. They transform the students’ effort from isolated acts of compassion into components of a system that can be evaluated, adjusted, improved. They provide the objective validation that Ibsen’s hypothesis required, extending the proof from a single patient to a population. They create a new form of medical authority, based not on seniority or specialty but on access to decisive information.

This authority does not go uncontested. The senior physicians who accepted Astrup’s guidance during the emergency begin to assert their prerogatives as the immediate crisis recedes. The laboratory service, expanded by emergency measures, faces pressure to contract, to return to its pre-epidemic scope, to yield space and resources to departments with longer histories and stronger institutional positions. On the last day of September, Astrup receives a formal memorandum from the hospital administration requesting a schedule for “normalization” of laboratory operations. He reads it standing at his bench, the pH meter humming its stabilization tone behind him, a syringe of fresh arterial blood cooling on the rack. He does not reply immediately. He draws the next sample, runs the next measurement, posts the next set of numbers. The data provides objective validation, but it also creates a new source of authority that challenges traditional hospital hierarchies.